merge: T102 phase 4 documentation update

Wires T93's `search_all_memories` service into a small read-only HTML
surface so users can find a memory across every chat in the database.

* `chat/web/search.py` (new): GET `/search?q=...` runs the FTS service
  with k=50, hydrates each row with bot name + scene timestamp, and
  renders `search.html`. Empty `q` short-circuits to no results so the
  top-bar form can submit even with an empty input.
* `chat/templates/search.html` (new): empty-state placeholder, results
  list with chat-level "Open chat" links (`/chats/{chat_id}` — memories
  don't carry an event_id today, so no per-turn anchor).
* `chat/templates/layout.html`: append a small `<form>` to the rail
  nav, additive only.
* `chat/app.py`: register `search_router` (additive import + include).
* `tests/test_search_ux.py`: 3 tests — multi-chat results, empty-query
  placeholder, chat link.

CLAUDE.md

@@ -287,3 +287,88 @@ New follow-ups discovered during Phase 3.5 reviews and execution. None are block
 - **Scene-close-on-cancel UX revisit** (Phase 2.5 carry-over): T74.3 pinned the existing behavior; revisit if real play-testing surfaces a regression.
 - **Cross-feature canned-queue brittleness**: meanwhile-scene close test required a canned response for T65's digest call after T64+T65 merge. Future close-path additions will keep extending the queue. Consider a structured fixture builder rather than positional canned arrays. NOT addressed in Phase 3.5.
 - **Lifecycle-transition rollback in regenerate**: T83.4 added a warning log; actual rollback (with proper schema linkage from lifecycle event back to producing turn) is Phase 4 work.
+
+## Phase 4 status
+
+Phase 4 polish shipped end-to-end across 15 tasks (T88–T102). Vector retrieval is functional via pure-Python cosine over a JSON-blob embeddings table (sqlite-vec deferred — host Python lacks loadable extensions). Branching is data-model + drawer UI. Surgical delete with cascade preview, hide-from-view soft delete, significance review panel, snapshot UX, and cross-chat search all surface from the drawer or top-bar. Test count grew from 343 (Phase 3.5) to ~413 (+70 new tests).
+
+- **Wave 1 — schema + Phase 3.6 carry-overs (parallel)**:
+  - **T88** `embeddings` table + projector handlers (pure-Python cosine, JSON-blob storage; sqlite-vec deferred).
+  - **T89** `branches` table + handlers (main bootstrapped; `is_active` flag; partial unique index).
+  - **T90** Phase 3.6 carry-overs trio — `read_recent_dialogue` chat-id SQL pushdown, lifecycle warning wording tightening, legacy `record_turn_memory` removed.
+- **Wave 2 — services (parallel)**:
+  - **T91** embedding generation service (Phase 4 ships a deterministic SHA-256-derived pseudo-embedding; real model swap is Phase 4.5+).
+  - **T92** vector search service via pure-Python cosine.
+  - **T93** cross-chat search service (FTS5 across all owners, no witness filter — admin-style).
+- **Wave 3 — services (parallel)**:
+  - **T94** branching service (`branch_from_event`, `switch_active_branch`, `list_branches_with_metadata`).
+  - **T95** delete-impact computation service (cascade preview, no DB mutation).
+- **Wave 4 — combined retrieval (single)**:
+  - **T96** combined FTS + vector retrieval ranking via reciprocal-rank fusion (RRF, `RRF_CONST=60`); existing significance/recency boost applied as final pass.
+- **Wave 5 — memory write hook + backfill (single)**:
+  - **T97** `EmbeddingWorker` drains queue and emits `embedding_indexed` events; `memory_write` enqueues per `memory_written`; `backfill_embeddings` script for existing memories; ALL 4 production call sites wired (turns, regenerate, meanwhile, drawer).
+- **Wave 6 — drawer Phase 4 bundle (single, 5 sub-features)**:
+  - **T98.1** branching UI (Branches panel + 3 routes).
+  - **T98.2** significance review panel (distribution bar chart + per-memory edit).
+  - **T98.3** hide-from-view toggle + `turn_hidden` `manual_edit` branch.
+  - **T98.4** surgical delete with cascade preview (reuses existing rewind path; pre-rewind snapshot preserved).
+  - **T98.5** remaining v1 edits — `narrative_anchor` + weather drawer affordances + 2 new `manual_edit` branches.
+- **Wave 7 — UX surfaces (parallel)**:
+  - **T99** snapshot UX (manual trigger, list, restore with hard-confirm, preview).
+  - **T100** cross-chat search UX (top-bar form + results page).
+- **Wave 8 — polish (parallel)**:
+  - **T101** cross-feature integration tests (5 multi-feature scenarios).
+  - **T102** documentation (this section).
+
+### Phase 4.5 / 5 backlog
+
+New follow-ups discovered during Phase 4 reviews and execution. None are blocking; pick up at any time.
+
+#### From T88 review
+
+- **`embeddings` FK lacks `ON DELETE CASCADE`**: deindex events are the only deletion path; if memories ever get deleted directly (raw SQL), embedding rows orphan. Defensible since projector model uses explicit deindex events, but worth a comment or `ON DELETE CASCADE` addition.
+
+#### From T89 review
+
+- **`list_branches(chat_id=...)` filter leaks global branches** (`chat_id IS NULL`) into every chat scope. Intentional? Document.
+- **Branch-switch to nonexistent silently leaves zero active branches** — log a warning when this would happen.
+
+#### From T91 review
+
+- **Real embedding model swap**: Phase 4 ships pseudo-embedding (deterministic SHA-256 hash). Phase 4.5+ should swap to a real model (Featherless `bge-small-en-v1.5` if available; or local `sentence-transformers/all-MiniLM-L6-v2`). The 384-dim is hardcoded in `0012_embeddings.sql`; if dim changes, migrate first.
+- **`timeout_s` unused on pseudo path** — fine, but log when non-default model falls through to fallback so misconfigured callers don't silently degrade.
+
+#### From T96 review
+
+- **Duplicate `MAX(id)` lookup** between `_composite_rerank` and the fused-path tail — DRY follow-up.
+- **`fts_rank=None` for vector-only rows** — document downstream contract.
+
+#### From T98 review
+
+- **`event_id <= 0` guard in `delete_turn`** — currently silently rewinds everything if `event_id` is 0. Add `if event_id <= 0: 400`.
+- **`html.escape()` on `compute_delete_impact` output rendered into the modal** — defense in depth (currently model-controlled strings, but if event payload fields ever appear in descriptions, autoescape needed).
+- **Extract delete-impact modal HTML to a Jinja partial** — testability + autoescape inheritance.
+
+#### From T99 review
+
+- **Hoist `datetime`/`timezone` imports to module level** in `chat/web/snapshots.py`.
+- **`kind` defaulting in restore/preview** — reject missing `kind` rather than silent 404.
+- **`created_at` from file mtime** vs filename-encoded timestamp — small drift if files copied; document.
+
+#### From T100 review
+
+- **Hardcoded `k=50`** — extract to module constant.
+- **N+1 lookups (`get_bot`/`get_chat`/`get_scene` per row)** — fine at `k=50`, revisit if `k` grows.
+- **FTS highlighting via `snippet()`** — Phase 4 skipped this; UX nice-to-have.
+- **Result links chat-level only** — `memories` table has no `event_id` column; deep-linking to specific turn requires schema addition.
+
+#### Deferred items
+
+- **sqlite-vec swap** when host Python supports `enable_load_extension`.
+- **Real embedding model** with proper semantic similarity.
+- **Branching read-side filter**: T89 ships data-model + UI but event readers don't yet consult `is_active`. Each branch is metadata-only labeled ranges. Consult-on-read is Phase 4.5+ work.
+- **Bulk significance re-rate** in drawer (T98.2 deferred — only per-memory edit shipped).
+- **Vector index optimization** (HNSW) — only relevant if memory counts grow past pure-Python feasibility.
+- **`scene-close-on-cancel` UX revisit** (Phase 2.5 carry-over).
+- **Cross-feature canned-queue brittleness fixture builder** (Phase 3 carry-over).
+- **Full lifecycle-rollback in regenerate** — Phase 3.5 T83.4 shipped a warning log; proper rollback needs schema-level back-references (`triggered_by_assistant_turn_id` payload field).

chat/app.py

@@ -16,6 +16,7 @@ from chat.db.migrate import apply_migrations
 from chat.eventlog.log import read_events
 from chat.eventlog.projector import apply_event
 from chat.services.background import BackgroundWorker
+from chat.services.embedding_worker import EmbeddingWorker
 from chat.services.snapshot import latest_snapshot_path, restore_from_snapshot
 
 # Trigger handler registration:
@@ -31,7 +32,9 @@ from chat.web.drawer import router as drawer_router
 from chat.web.kickoff import router as kickoff_router
 from chat.web.middleware import FirstRunRedirectMiddleware
 from chat.web.nav import router as nav_router
+from chat.web.search import router as search_router
 from chat.web.settings import router as settings_router
+from chat.web.snapshots import router as snapshots_router
 from chat.web.sse import router as sse_router
 from chat.web.turns import router as turns_router
 
@@ -85,9 +88,23 @@ async def lifespan(app: FastAPI):
     await worker.start()
     app.state.background_worker = worker
 
+    # T97: separate worker for the async embedding pass. Each
+    # ``memory_written`` enqueues an EmbeddingJob; the worker drains the
+    # queue, calls ``generate_embedding``, and emits ``embedding_indexed``.
+    # Phase 4's pseudo-embedding path is local so the worker doesn't need
+    # an LLM client; we still pass one so the Phase 4.5 swap to a real
+    # model is a one-line change.
+    embedding_worker = EmbeddingWorker(
+        conn_factory=lambda: open_db(settings.db_path),
+        client=_factory(),
+    )
+    await embedding_worker.start()
+    app.state.embedding_worker = embedding_worker
+
     try:
         yield
     finally:
+        await embedding_worker.stop()
         await worker.stop()
 
 
@@ -122,9 +139,11 @@ async def http_exception_handler(request: Request, exc: StarletteHTTPException):
 app.include_router(bots_router)
 app.include_router(kickoff_router)
 app.include_router(settings_router)
+app.include_router(snapshots_router)
 app.include_router(nav_router)
 app.include_router(chat_router)
 app.include_router(drawer_router)
+app.include_router(search_router)
 app.include_router(sse_router)
 app.include_router(turns_router)
 

chat/db/migrations/0012_embeddings.sql

@@ -0,0 +1,14 @@
+-- Embeddings stored as JSON arrays (pure-Python cosine at query time).
+-- Phase 4.5+ may swap to sqlite-vec when the host Python supports
+-- loadable extensions; the schema is intentionally simple to make that
+-- migration straightforward.
+CREATE TABLE embeddings (
+    memory_id INTEGER PRIMARY KEY,
+    vector_json TEXT NOT NULL,   -- JSON array of floats, length = dim
+    model TEXT NOT NULL,
+    dim INTEGER NOT NULL,
+    indexed_at TEXT NOT NULL DEFAULT (datetime('now')),
+    FOREIGN KEY (memory_id) REFERENCES memories(id)
+);
+
+CREATE INDEX embeddings_model_idx ON embeddings(model);

chat/db/migrations/0013_branches.sql

@@ -0,0 +1,17 @@
+CREATE TABLE branches (
+    id INTEGER PRIMARY KEY,
+    name TEXT NOT NULL UNIQUE,
+    origin_event_id INTEGER NOT NULL,
+    head_event_id INTEGER NOT NULL,
+    chat_id TEXT,
+    created_at TEXT NOT NULL DEFAULT (datetime('now')),
+    is_active INTEGER NOT NULL DEFAULT 0
+);
+
+-- Exactly one row may have is_active = 1 at any time.
+CREATE UNIQUE INDEX branches_active_idx ON branches(is_active) WHERE is_active = 1;
+
+-- Bootstrap the main branch. origin_event_id=0 + head_event_id=0 are
+-- placeholder seeds; the orchestrator updates head as new events land.
+INSERT INTO branches (name, origin_event_id, head_event_id, is_active)
+VALUES ('main', 0, 0, 1);

chat/services/branching.py

@@ -0,0 +1,107 @@
+"""Branching service (T94, Phase 4).
+
+Wraps branches state with validation + event emission. Phase 4 ships
+the data model and creation/switching APIs; the read-side filter
+(event readers consulting is_active) is a Phase 4.5+ follow-up — for
+now branches are metadata-only and the existing event readers remain
+branch-agnostic. The drawer UI (T98) drives create/switch via these
+helpers.
+"""
+
+from __future__ import annotations
+from sqlite3 import Connection
+
+from chat.eventlog.log import append_and_apply
+from chat.state.branches import get_branch, list_branches, active_branch  # noqa: F401
+
+
+def branch_from_event(
+    conn: Connection,
+    *,
+    name: str,
+    origin_event_id: int,
+    chat_id: str | None = None,
+) -> int:
+    """Create a new named branch forking from origin_event_id.
+
+    Emits a branch_created event. Returns the new branch's row id.
+    Raises ValueError if name already exists or origin_event_id doesn't
+    correspond to a real event."""
+    if not name or not name.strip():
+        raise ValueError("branch name must be non-empty")
+
+    if get_branch(conn, name) is not None:
+        raise ValueError(f"branch {name!r} already exists")
+
+    # Validate origin_event_id is a real event id (or 0 for the bootstrap case
+    # which only main uses).
+    if origin_event_id < 0:
+        raise ValueError(f"origin_event_id must be >= 0, got {origin_event_id}")
+    if origin_event_id > 0:
+        row = conn.execute(
+            "SELECT 1 FROM event_log WHERE id = ?", (origin_event_id,)
+        ).fetchone()
+        if row is None:
+            raise ValueError(
+                f"origin_event_id {origin_event_id} does not exist in event_log"
+            )
+
+    append_and_apply(
+        conn,
+        kind="branch_created",
+        payload={
+            "name": name,
+            "origin_event_id": origin_event_id,
+            "head_event_id": origin_event_id,  # head starts at origin
+            "chat_id": chat_id,
+        },
+    )
+
+    branch = get_branch(conn, name)
+    if branch is None:
+        # Should be unreachable if append_and_apply worked.
+        raise RuntimeError(f"branch {name!r} not found after creation")
+    return branch["id"]
+
+
+def switch_active_branch(conn: Connection, *, name: str) -> None:
+    """Make the named branch active. Emits branch_switched."""
+    if get_branch(conn, name) is None:
+        raise ValueError(f"branch {name!r} does not exist")
+
+    append_and_apply(
+        conn,
+        kind="branch_switched",
+        payload={"name": name},
+    )
+
+
+def list_branches_with_metadata(
+    conn: Connection, chat_id: str | None = None
+) -> list[dict]:
+    """List branches with computed event_count metadata.
+
+    event_count = head_event_id - origin_event_id + 1 (when both are set)
+                  OR head_event_id (when origin is 0, e.g., main branch)
+                  OR 0 (when head <= origin, which is the bootstrap state)
+    """
+    branches = list_branches(conn, chat_id)
+    enriched = []
+    for b in branches:
+        origin = b["origin_event_id"]
+        head = b["head_event_id"]
+        if head < origin:
+            event_count = 0
+        elif origin == 0:
+            event_count = head
+        else:
+            event_count = head - origin + 1
+        enriched.append({**b, "event_count": event_count})
+    return enriched
+
+
+__all__ = [
+    "branch_from_event",
+    "switch_active_branch",
+    "list_branches_with_metadata",
+]

chat/services/cross_chat_search.py

@@ -0,0 +1,75 @@
+"""Cross-chat search service (T93, Phase 4).
+
+FTS5-based search across ALL owners and ALL chats. Used by the
+top-bar search UX (T100) for "where did I last see this character
+mention X?" queries. NO witness filter -- this is intentionally a
+power-user surface that surfaces memories across POVs.
+
+Mirrors the FTS5 access pattern of ``chat.state.memory.search_memories``
+but drops both the ``owner_id = ?`` and the per-witness predicates so a
+single query can sweep every chat in the database. The composite
+re-rank is also dropped: callers want raw BM25 ordering for the
+"highest match strength wins" semantics expected of a global search box.
+"""
+
+from __future__ import annotations
+
+from sqlite3 import Connection
+
+
+def search_all_memories(
+    conn: Connection,
+    *,
+    query: str,
+    k: int = 20,
+) -> list[dict]:
+    """Search FTS5 across all owners and chats.
+
+    Returns rows with ``{memory_id, owner_id, chat_id, scene_id,
+    pov_summary, significance, ts, fts_rank}``, sorted by FTS5 BM25
+    rank ascending (lower rank = stronger match, surfaced first).
+
+    The ``memories`` table has no ``ts`` column; we expose ``created_at``
+    (the projector-side row insertion timestamp) under that key so the
+    UI does not have to know the storage name.
+
+    An empty / whitespace-only ``query`` short-circuits to ``[]`` to
+    avoid an FTS5 ``MATCH ''`` syntax error and to keep the top-bar
+    "no input yet" state from triggering a full-table scan.
+    """
+    if not query or not query.strip():
+        return []
+
+    # FTS5 MATCH against the same ``memories_fts`` virtual table that
+    # backs ``state.memory.search_memories``; the JOIN pulls metadata
+    # from the content table because the FTS index only stores
+    # ``pov_summary``. ORDER BY rank ASC because BM25 in FTS5 returns
+    # negative scores where lower is better.
+    rows = conn.execute(
+        "SELECT m.id, m.owner_id, m.chat_id, m.scene_id, "
+        "       m.pov_summary, m.significance, m.created_at, "
+        "       memories_fts.rank "
+        "FROM memories_fts "
+        "JOIN memories m ON m.id = memories_fts.rowid "
+        "WHERE memories_fts MATCH ? "
+        "ORDER BY memories_fts.rank ASC "
+        "LIMIT ?",
+        (query.strip(), k),
+    ).fetchall()
+
+    return [
+        {
+            "memory_id": r[0],
+            "owner_id": r[1],
+            "chat_id": r[2],
+            "scene_id": r[3],
+            "pov_summary": r[4],
+            "significance": r[5],
+            "ts": r[6],
+            "fts_rank": r[7],
+        }
+        for r in rows
+    ]
+
+
+__all__ = ["search_all_memories"]

chat/services/delete_impact.py

@@ -0,0 +1,147 @@
+"""Delete-impact computation service (T95, Phase 4).
+
+Walks event_log forward from a target event_id and produces an ImpactReport
+describing what would be removed if rewind-to-target were invoked. Pure
+computation — does NOT mutate the database. Used by T98's drawer surgical-
+delete UI to render an 'are you sure?' modal before invoking the actual
+rewind path (chat/services/rewind.py).
+"""
+
+from __future__ import annotations
+import json
+from sqlite3 import Connection
+
+from pydantic import BaseModel, Field
+
+
+class DeletedItem(BaseModel):
+    kind: str
+    description: str
+    target_id: int | str | None = None
+
+
+class ImpactReport(BaseModel):
+    target_event_id: int
+    cascading: list[DeletedItem] = Field(default_factory=list)
+    notes: list[str] = Field(default_factory=list)
+
+
+def _excerpt(text: str, n: int = 60) -> str:
+    text = (text or "").strip().replace("\n", " ")
+    return text if len(text) <= n else text[: n - 1] + "…"
+
+
+def compute_delete_impact(
+    conn: Connection,
+    *,
+    target_event_id: int,
+) -> ImpactReport:
+    """Compute the cascading impact of rewinding to target_event_id."""
+    # Verify target exists.
+    target_row = conn.execute(
+        "SELECT id, kind, payload_json FROM event_log WHERE id = ?",
+        (target_event_id,),
+    ).fetchone()
+    if target_row is None:
+        return ImpactReport(
+            target_event_id=target_event_id,
+            cascading=[],
+            notes=[f"target event_id {target_event_id} not found"],
+        )
+
+    # Walk forward: every event with id >= target_event_id is in scope.
+    rows = conn.execute(
+        "SELECT id, kind, payload_json FROM event_log "
+        "WHERE id >= ? ORDER BY id ASC",
+        (target_event_id,),
+    ).fetchall()
+
+    cascading: list[DeletedItem] = []
+    notes: list[str] = []
+    scene_close_present = False
+    regenerated_from = None
+
+    for row_id, kind, payload_json in rows:
+        try:
+            payload = json.loads(payload_json) if payload_json else {}
+        except (json.JSONDecodeError, TypeError):
+            payload = {}
+
+        if kind == "memory_written":
+            cascading.append(
+                DeletedItem(
+                    kind=kind,
+                    description=f"memory: {_excerpt(payload.get('pov_summary', ''))}",
+                    target_id=payload.get("memory_id"),
+                )
+            )
+        elif kind == "edge_update":
+            src = payload.get("source_id", "?")
+            tgt = payload.get("target_id", "?")
+            cascading.append(
+                DeletedItem(
+                    kind=kind,
+                    description=f"edge update: {src} -> {tgt}",
+                    target_id=f"{src}->{tgt}",
+                )
+            )
+        elif kind == "scene_closed":
+            scene_close_present = True
+            cascading.append(
+                DeletedItem(
+                    kind=kind,
+                    description=f"scene close at {payload.get('closed_at', '?')}",
+                    target_id=payload.get("scene_id"),
+                )
+            )
+        elif kind in ("user_turn", "user_turn_edit", "assistant_turn"):
+            speaker = payload.get("speaker_id") or ("you" if kind.startswith("user") else "?")
+            prose = payload.get("prose") or payload.get("text") or ""
+            cascading.append(
+                DeletedItem(
+                    kind=kind,
+                    description=f"turn {row_id} ({speaker}: {_excerpt(prose, 50)})",
+                    target_id=row_id,
+                )
+            )
+            if regenerated_from is None and payload.get("regenerated_from"):
+                regenerated_from = payload["regenerated_from"]
+        elif kind == "manual_edit":
+            target_kind = payload.get("target_kind", "?")
+            cascading.append(
+                DeletedItem(
+                    kind=kind,
+                    description=f"manual edit: {target_kind}",
+                    target_id=payload.get("target_id"),
+                )
+            )
+        else:
+            cascading.append(
+                DeletedItem(
+                    kind=kind,
+                    description=f"{kind} event",
+                    target_id=row_id,
+                )
+            )
+
+    # Notes / warnings.
+    notes.append(f"{len(rows)} events would be discarded total")
+    if scene_close_present:
+        notes.append(
+            "scene close events are in scope — closing-scene per-POV summaries "
+            "and group_node updates will be reverted"
+        )
+    if regenerated_from is not None:
+        notes.append(
+            f"target turn was regenerated from event_id {regenerated_from}; "
+            f"the original turn remains intact"
+        )
+
+    return ImpactReport(
+        target_event_id=target_event_id,
+        cascading=cascading,
+        notes=notes,
+    )
+
+
+__all__ = ["DeletedItem", "ImpactReport", "compute_delete_impact"]

chat/services/embedding_worker.py

@@ -0,0 +1,137 @@
+"""Embedding worker (T97, Phase 4).
+
+Drains a queue of embedding jobs. Each job carries a memory id and the
+narrative text to embed; the worker calls
+:func:`chat.services.embeddings.generate_embedding` and emits an
+``embedding_indexed`` event so the projector lands the vector in the
+``embeddings`` table.
+
+Mirrors the :class:`chat.services.background.BackgroundWorker` pattern:
+single asyncio task, sentinel-based shutdown, exceptions are caught and
+logged so a flaky embedding call doesn't take down the worker. Each job
+opens its own SQLite connection via ``conn_factory`` — the request path
+and the worker do not share connections.
+
+Featherless concurrency (the 2-conn cap) is respected by virtue of the
+single-task design: jobs run strictly serially. Phase 4's pseudo-embedding
+path is local and synchronous so this is largely moot, but the pattern
+is in place for the Phase 4.5+ real-embedding swap.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+from dataclasses import dataclass
+from sqlite3 import Connection
+from typing import Callable
+
+from chat.eventlog.log import append_and_apply
+from chat.services.embeddings import (
+    DEFAULT_EMBEDDING_DIM,
+    DEFAULT_EMBEDDING_MODEL,
+    FALLBACK_EMBEDDING_MODEL,
+    generate_embedding,
+)
+
+
+log = logging.getLogger(__name__)
+
+
+@dataclass
+class EmbeddingJob:
+    """One unit of work for the embedding worker.
+
+    ``memory_id`` is the row to attach the vector to; ``text`` is the
+    narrative text to embed (typically ``memories.pov_summary``).
+    """
+
+    memory_id: int
+    text: str
+
+
+class EmbeddingWorker:
+    """asyncio.Queue-backed single-worker task for embedding generation.
+
+    Started on app startup; ``stop()`` enqueues a sentinel and awaits
+    the task so any in-flight job has a chance to finish. Pending jobs
+    after the sentinel are dropped on shutdown.
+    """
+
+    def __init__(
+        self,
+        *,
+        conn_factory: Callable[[], Connection],
+        client,  # LLMClient | None — unused on the pseudo path.
+        model: str = DEFAULT_EMBEDDING_MODEL,
+        dim: int = DEFAULT_EMBEDDING_DIM,
+        enabled: bool = True,
+    ) -> None:
+        self._queue: asyncio.Queue[EmbeddingJob | None] = asyncio.Queue()
+        self._conn_factory = conn_factory
+        self._client = client
+        self._model = model
+        self._dim = dim
+        self._task: asyncio.Task | None = None
+        self.enabled = enabled
+
+    def enqueue(self, job: EmbeddingJob) -> None:
+        if not self.enabled:
+            return
+        self._queue.put_nowait(job)
+
+    async def start(self) -> None:
+        if self._task is None:
+            self._task = asyncio.create_task(self._run())
+
+    async def stop(self) -> None:
+        if self._task is None:
+            return
+        self._queue.put_nowait(None)  # sentinel
+        await self._task
+        self._task = None
+
+    async def _run(self) -> None:
+        while True:
+            job = await self._queue.get()
+            if job is None:
+                return
+            try:
+                await self._process(job)
+            except Exception as exc:  # noqa: BLE001 — worker must not die
+                log.warning(
+                    "embedding worker failed for memory_id=%s: %s",
+                    job.memory_id,
+                    exc,
+                    exc_info=True,
+                )
+
+    async def _process(self, job: EmbeddingJob) -> None:
+        result = await generate_embedding(
+            self._client,
+            text=job.text,
+            model=self._model,
+            dim=self._dim,
+        )
+        if result.model == FALLBACK_EMBEDDING_MODEL:
+            # Don't index a fallback (zero) vector — the backfill script
+            # can retry later once a real embedding is available.
+            log.debug(
+                "embedding worker skipping fallback result for memory_id=%s",
+                job.memory_id,
+            )
+            return
+        with self._conn_factory() as conn:
+            append_and_apply(
+                conn,
+                kind="embedding_indexed",
+                payload={
+                    "memory_id": job.memory_id,
+                    "model": result.model,
+                    "dim": result.dim,
+                    "vector": result.vector,
+                },
+            )
+
+
+__all__ = ["EmbeddingJob", "EmbeddingWorker"]

chat/services/embeddings.py

@@ -0,0 +1,108 @@
+"""Embedding generation service (T91, Phase 4).
+
+Wraps the embedding API call. For Phase 4's first cut we ship a
+deterministic local pseudo-embedding (hash-derived) so the vector
+retrieval pipeline can land without an external embedding endpoint
+or heavy local dependency. Phase 4.5+ swaps to a real model — the
+EmbeddingResult shape stays the same, only the generator changes.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import math
+import struct
+
+from pydantic import BaseModel
+
+from chat.llm.client import LLMClient
+
+
+DEFAULT_EMBEDDING_DIM = 384
+DEFAULT_EMBEDDING_MODEL = "pseudo-sha256-384"
+FALLBACK_EMBEDDING_MODEL = "fallback"
+
+
+class EmbeddingResult(BaseModel):
+    vector: list[float]
+    model: str
+    dim: int
+
+
+def _pseudo_embed(text: str, dim: int = DEFAULT_EMBEDDING_DIM) -> list[float]:
+    """Deterministic pseudo-embedding for Phase 4 first cut.
+
+    Hashes the text with SHA-256, then expands by re-hashing each
+    successive block with the previous block + a counter — this gives
+    ``dim * 4`` bytes of fresh entropy per input rather than naively
+    repeating the 32-byte digest (which would collapse the vector onto
+    only 8 unique floats and make distinct inputs cosine-similar).
+
+    Bytes are unpacked as little-endian int32s and rescaled to [-1, 1]
+    so we sidestep the float32 NaN/denormal values that ``struct.unpack
+    'f'`` would otherwise produce on raw hash bytes. The result is
+    unit-normalized so cosine similarity reduces to a dot product.
+
+    NOT semantically meaningful — just consistent for testing the
+    pipeline. Phase 4.5 should swap to a real embedding model.
+    """
+    needed = dim * 4  # 4 bytes per int32
+    seed = text.encode("utf-8")
+    chunks: list[bytes] = []
+    counter = 0
+    while sum(len(c) for c in chunks) < needed:
+        block = hashlib.sha256(seed + counter.to_bytes(4, "big")).digest()
+        chunks.append(block)
+        counter += 1
+    full = b"".join(chunks)[:needed]
+    ints = struct.unpack(f"<{dim}i", full)
+    # Map int32 to roughly [-1, 1] — exact bound doesn't matter since we
+    # normalize, but keeps values numerically tame.
+    raw = [x / 2147483648.0 for x in ints]
+    norm = math.sqrt(sum(x * x for x in raw)) or 1.0
+    return [x / norm for x in raw]
+
+
+async def generate_embedding(
+    client: LLMClient,
+    *,
+    text: str,
+    model: str = DEFAULT_EMBEDDING_MODEL,
+    dim: int = DEFAULT_EMBEDDING_DIM,
+    timeout_s: float = 30.0,
+) -> EmbeddingResult:
+    """Generate an embedding for the given text.
+
+    Phase 4 default uses a deterministic local pseudo-embedding. If
+    the LLMClient grows an ``embed(...)`` method in Phase 4.5, this
+    wrapper will route to it when ``model != "pseudo-sha256-384"``.
+
+    Falls back to a zero vector with ``model="fallback"`` on any
+    failure (callers detect the sentinel and skip indexing). For the
+    pseudo path, failure is structurally impossible — it's pure local
+    computation.
+    """
+    if not text or not text.strip():
+        # Empty input — return fallback so caller doesn't index empty rows.
+        return EmbeddingResult(
+            vector=[0.0] * dim, model=FALLBACK_EMBEDDING_MODEL, dim=dim
+        )
+
+    if model == DEFAULT_EMBEDDING_MODEL:
+        # Pure-local pseudo path — no LLMClient call.
+        return EmbeddingResult(vector=_pseudo_embed(text, dim), model=model, dim=dim)
+
+    # Future: real embedding via client.embed(...). Phase 4.5 work.
+    # For Phase 4, any non-default model falls through to fallback.
+    return EmbeddingResult(
+        vector=[0.0] * dim, model=FALLBACK_EMBEDDING_MODEL, dim=dim
+    )
+
+
+__all__ = [
+    "DEFAULT_EMBEDDING_DIM",
+    "DEFAULT_EMBEDDING_MODEL",
+    "FALLBACK_EMBEDDING_MODEL",
+    "EmbeddingResult",
+    "generate_embedding",
+]

chat/services/memory_write.py

@@ -13,6 +13,14 @@ Phase 1 simplifications (per plan §11.1, T27 will refine):
   pass overwrites via a follow-up event.
 - Witness flags are hard-coded ``[you=1, host=1, guest=0]``. Phase 2 will
   derive them from ``chat.guest_bot_id`` once a guest can be present.
+
+T97 (Phase 4): each successful memory write also enqueues an
+:class:`~chat.services.embedding_worker.EmbeddingJob` on the
+lifespan-managed embedding worker, so the just-written memory gets a
+vector indexed out-of-band. The hook is opt-in via the ``app`` kwarg —
+callers without a FastAPI app handle (e.g. one-off scripts, isolated
+unit tests) simply don't enqueue, and the backfill script can pick up
+those rows later.
 """
 
 from __future__ import annotations
@@ -20,62 +28,7 @@ from __future__ import annotations
 from sqlite3 import Connection
 
 from chat.eventlog.log import append_and_apply
-
+from chat.services.embedding_worker import EmbeddingJob
-
-def record_turn_memory(
-    conn: Connection,
-    *,
-    chat_id: str,
-    host_bot_id: str,
-    narrative_text: str,
-    scene_id: int | None = None,
-    chat_clock_at: str | None = None,
-    source: str = "direct",
-    significance: int = 1,
-) -> tuple[int, int | None]:
-    """Append a ``memory_written`` event for the host bot's POV of this turn.
-
-    Uses :func:`chat.eventlog.log.append_and_apply` (not raw
-    :func:`append_event`) so the new memory row is projected immediately
-    without re-running prior non-idempotent handlers (e.g. ``edge_update``
-    deltas).
-
-    Returns ``(event_id, memory_id)``. ``event_id`` is the row id of the
-    just-appended ``memory_written`` event in ``event_log``. ``memory_id``
-    is the autoincrement PK of the corresponding ``memories`` row — these
-    are *different* numbers (event_log and memories use independent
-    rowid sequences) so callers needing to update significance or pin
-    state must use ``memory_id``. Falls back to ``None`` if the projected
-    row can't be located, which shouldn't happen but keeps the return
-    shape stable.
-    """
-    payload: dict = {
-        "owner_id": host_bot_id,
-        "chat_id": chat_id,
-        "pov_summary": narrative_text,
-        "witness_you": 1,
-        "witness_host": 1,
-        "witness_guest": 0,
-        "source": source,
-        "reliability": 1.0,
-        "significance": significance,
-        "pinned": 0,
-        "auto_pinned": 0,
-    }
-    if scene_id is not None:
-        payload["scene_id"] = scene_id
-    if chat_clock_at is not None:
-        payload["chat_clock_at"] = chat_clock_at
-
-    event_id = append_and_apply(conn, kind="memory_written", payload=payload)
-    row = conn.execute(
-        "SELECT id FROM memories "
-        "WHERE owner_id = ? AND chat_id = ? "
-        "ORDER BY id DESC LIMIT 1",
-        (host_bot_id, chat_id),
-    ).fetchone()
-    memory_id = row[0] if row else None
-    return event_id, memory_id
 
 
 def _write_one_memory(
@@ -91,9 +44,16 @@ def _write_one_memory(
     chat_clock_at: str | None,
     source: str,
     significance: int,
+    app=None,
 ) -> tuple[int, int | None]:
     """Append a single ``memory_written`` event for ``owner_id`` and return
-    ``(event_id, memory_id)`` for the projected row."""
+    ``(event_id, memory_id)`` for the projected row.
+
+    When ``app`` is provided and ``app.state.embedding_worker`` exists,
+    enqueue an :class:`EmbeddingJob` for the freshly-projected memory id
+    (T97). Skipped silently if the worker is absent or the projected row
+    can't be located — the backfill script handles missing-vector rows.
+    """
     payload: dict = {
         "owner_id": owner_id,
         "chat_id": chat_id,
@@ -120,6 +80,23 @@ def _write_one_memory(
         (owner_id, chat_id),
     ).fetchone()
     memory_id = row[0] if row else None
+
+    # T97: enqueue an embedding job for the just-written memory. The
+    # worker drains the queue out-of-band and emits an
+    # ``embedding_indexed`` event when the vector is ready. ``getattr``
+    # keeps this a no-op for callers without a wired-up app (scripts,
+    # tests) — the backfill script handles those rows.
+    if memory_id is not None and narrative_text and narrative_text.strip():
+        worker = (
+            getattr(app.state, "embedding_worker", None)
+            if app is not None
+            else None
+        )
+        if worker is not None:
+            worker.enqueue(
+                EmbeddingJob(memory_id=memory_id, text=narrative_text)
+            )
+
     return event_id, memory_id
 
 
@@ -135,6 +112,7 @@ def record_turn_memory_for_present(
     source: str = "direct",
     significance: int = 1,
     you_present: bool = True,
+    app=None,
 ) -> dict[str, tuple[int, int | None]]:
     """Single entry-point for per-turn memory writes (T84).
 
@@ -153,6 +131,9 @@ def record_turn_memory_for_present(
       with ``you_present=False`` is a programming error and raises
       :class:`ValueError`.
 
+    When ``app`` is provided, each per-witness write also enqueues an
+    :class:`EmbeddingJob` on ``app.state.embedding_worker`` (T97).
+
     Returns a mapping ``{bot_id: (event_id, memory_id)}`` so callers can
     look up the freshly-projected memory id per owner without re-querying
     the database.
@@ -177,6 +158,7 @@ def record_turn_memory_for_present(
         chat_clock_at=chat_clock_at,
         source=source,
         significance=significance,
+        app=app,
     )
     if guest_bot_id is not None:
         result[guest_bot_id] = _write_one_memory(
@@ -191,6 +173,7 @@ def record_turn_memory_for_present(
             chat_clock_at=chat_clock_at,
             source=source,
             significance=significance,
+            app=app,
         )
     return result
 
@@ -206,6 +189,7 @@ def record_meanwhile_memory(
     chat_clock_at: str | None = None,
     source: str = "direct",
     significance: int = 1,
+    app=None,
 ) -> dict[str, tuple[int, int | None]]:
     """Backward-compat thin wrapper for meanwhile memory writes (T64, T84).
 
@@ -225,4 +209,5 @@ def record_meanwhile_memory(
         source=source,
         significance=significance,
         you_present=False,
+        app=app,
     )

chat/services/regenerate.py

@@ -103,6 +103,7 @@ async def regenerate_assistant_turn(
     chat_id: str,
     original_assistant_event_id: int,
     edited_user_prose: str | None = None,
+    app=None,
 ) -> str:
     """Regenerate the assistant turn linked to ``original_assistant_event_id``.
 
@@ -182,9 +183,13 @@ async def regenerate_assistant_turn(
         (chat_id, original_assistant_event_id),
     ).fetchall()
     if unrolled_lifecycle:
+        # T90.2: phrased as "at-or-after turn <id>" rather than "from
+        # superseded turn" because regenerating an OLDER turn lists
+        # intervening-turn transitions that legitimately stand on their
+        # own — those weren't authored by the superseded turn itself.
         _log.warning(
-            "regenerate_assistant_turn: %d lifecycle transition(s) from "
+            "regenerate_assistant_turn: %d lifecycle transition(s) "
-            "superseded turn %s are NOT being rolled back (Phase 4 "
+            "at-or-after turn %s are NOT being rolled back (Phase 4 "
             "follow-up). Affected event ids: %s",
             len(unrolled_lifecycle),
             original_assistant_event_id,
@@ -410,6 +415,7 @@ async def regenerate_assistant_turn(
         narrative_text=new_text,
         scene_id=scene["id"] if scene else None,
         chat_clock_at=chat.get("time"),
+        app=app,
     )
 
     last_at = chat.get("time")
@@ -644,6 +650,7 @@ async def regenerate_assistant_turn(
                 narrative_text=interject_text,
                 scene_id=scene["id"] if scene else None,
                 chat_clock_at=chat.get("time"),
+                app=app,
             )
 
             # Re-run the multi-pair state-update with the post-interjection

chat/services/turn_common.py

@@ -54,14 +54,21 @@ def read_recent_dialogue(
     regenerate to drop the original assistant_turn from its prompt
     context window before that row has been marked superseded (the
     supersede UPDATE lands at the end so the new event_id is known).
+
+    T90.1: the chat_id filter is pushed into SQL via ``json_extract`` so
+    ``LIMIT N`` always returns N rows scoped to the requested chat. The
+    previous implementation filtered chat_id post-fetch in Python, which
+    let foreign-chat rows fill the LIMIT and yield fewer than N relevant
+    rows in busy multi-chat databases.
     """
     if exclude_event_id is None:
         cur = conn.execute(
             "SELECT id, kind, payload_json FROM event_log "
             "WHERE kind IN ('user_turn', 'user_turn_edit', 'assistant_turn') "
             "  AND superseded_by IS NULL AND hidden = 0 "
+            "  AND json_extract(payload_json, '$.chat_id') = ? "
             "ORDER BY id DESC LIMIT ?",
-            (limit,),
+            (chat_id, limit),
         )
     else:
         cur = conn.execute(
@@ -69,15 +76,14 @@ def read_recent_dialogue(
             "WHERE kind IN ('user_turn', 'user_turn_edit', 'assistant_turn') "
             "  AND id != ? "
             "  AND superseded_by IS NULL AND hidden = 0 "
+            "  AND json_extract(payload_json, '$.chat_id') = ? "
             "ORDER BY id DESC LIMIT ?",
-            (exclude_event_id, limit),
+            (exclude_event_id, chat_id, limit),
         )
     rows = list(reversed(cur.fetchall()))
     out: list[dict] = []
     for row_id, kind, payload_json in rows:
         p = json.loads(payload_json)
-        if p.get("chat_id") != chat_id:
-            continue
         if kind in ("user_turn", "user_turn_edit"):
             out.append(
                 {

chat/services/vector_search.py

@@ -0,0 +1,79 @@
+"""Vector search service (T92, Phase 4).
+
+Pure-Python cosine similarity over the embeddings table. Phase 4 ships
+this without sqlite-vec because the host Python build doesn't support
+loadable extensions. For single-user scale (< few thousand memories
+per owner), iterating in Python is sub-millisecond.
+
+Phase 4.5+ may swap to sqlite-vec when the host Python supports
+enable_load_extension; the public API stays stable.
+"""
+
+from __future__ import annotations
+import math
+from sqlite3 import Connection
+
+from chat.state.embeddings import list_embeddings_for_owner
+
+
+_VALID_WITNESS_ROLES = {"you", "host", "guest"}
+
+
+def _cosine_similarity(a: list[float], b: list[float]) -> float:
+    """Cosine similarity. Assumes both vectors are non-zero."""
+    if len(a) != len(b):
+        return 0.0
+    dot = sum(x * y for x, y in zip(a, b))
+    norm_a = math.sqrt(sum(x * x for x in a)) or 1.0
+    norm_b = math.sqrt(sum(x * x for x in b)) or 1.0
+    return dot / (norm_a * norm_b)
+
+
+def vector_search(
+    conn: Connection,
+    *,
+    owner_id: str,
+    witness_role: str,    # "you" | "host" | "guest"
+    query_vector: list[float],
+    k: int = 4,
+) -> list[dict]:
+    """Return top-K memories by cosine similarity to query_vector,
+    witness-filtered for the viewer's POV. Returns rows with
+    {memory_id, pov_summary, significance, score} sorted by score
+    DESC. Empty list if no embeddings indexed for this owner.
+    """
+    if witness_role not in _VALID_WITNESS_ROLES:
+        raise ValueError(
+            f"witness_role must be one of {_VALID_WITNESS_ROLES}, got {witness_role!r}"
+        )
+
+    rows = list_embeddings_for_owner(conn, owner_id)
+    if not rows:
+        return []
+
+    # Witness-filter by the requesting role.
+    witness_key = f"witness_{witness_role}"
+    filtered = [r for r in rows if r.get(witness_key) == 1]
+    if not filtered:
+        return []
+
+    scored: list[tuple[float, dict]] = []
+    for row in filtered:
+        score = _cosine_similarity(query_vector, row["vector"])
+        scored.append(
+            (
+                score,
+                {
+                    "memory_id": row["memory_id"],
+                    "pov_summary": row["pov_summary"],
+                    "significance": row["significance"],
+                    "score": score,
+                },
+            )
+        )
+
+    scored.sort(key=lambda t: t[0], reverse=True)
+    return [item for _, item in scored[:k]]
+
+
+__all__ = ["vector_search"]

chat/state/branches.py

@@ -0,0 +1,133 @@
+"""Branches projector + readers (T89, Phase 4).
+
+A branch is a named fork of the event log. The 'main' branch is bootstrapped
+by migration 0013 with is_active=1. Subsequent branches reference an
+origin_event_id (the event they forked from). Phase 4 enables creation
+and switching; the read-side filter (event readers consulting is_active)
+is a Phase 4.5 follow-up — for now branches are metadata-only and the
+existing event readers remain branch-agnostic.
+"""
+
+from __future__ import annotations
+from sqlite3 import Connection
+
+from chat.eventlog.projector import on
+from chat.eventlog.log import Event
+
+
+@on("branch_created")
+def _apply_branch_created(conn: Connection, e: Event) -> None:
+    """Insert a new branch row with is_active=0. Idempotent via INSERT OR IGNORE."""
+    p = e.payload
+    conn.execute(
+        "INSERT OR IGNORE INTO branches "
+        "(name, origin_event_id, head_event_id, chat_id, is_active) "
+        "VALUES (?, ?, ?, ?, 0)",
+        (
+            p["name"],
+            int(p["origin_event_id"]),
+            int(p.get("head_event_id", p["origin_event_id"])),
+            p.get("chat_id"),
+        ),
+    )
+
+
+@on("branch_switched")
+def _apply_branch_switched(conn: Connection, e: Event) -> None:
+    """Set is_active=1 on the named branch and is_active=0 on all others.
+
+    Atomic via two UPDATEs ordered to avoid the unique-active-index race.
+    """
+    p = e.payload
+    name = p["name"]
+    # Clear ALL is_active flags first (avoids the unique-index trip).
+    conn.execute("UPDATE branches SET is_active = 0 WHERE is_active = 1")
+    conn.execute(
+        "UPDATE branches SET is_active = 1 WHERE name = ?",
+        (name,),
+    )
+
+
+@on("branch_head_updated")
+def _apply_branch_head_updated(conn: Connection, e: Event) -> None:
+    """Update head_event_id on the named branch."""
+    p = e.payload
+    conn.execute(
+        "UPDATE branches SET head_event_id = ? WHERE name = ?",
+        (int(p["head_event_id"]), p["name"]),
+    )
+
+
+def get_branch(conn: Connection, name: str) -> dict | None:
+    row = conn.execute(
+        "SELECT id, name, origin_event_id, head_event_id, chat_id, "
+        "       created_at, is_active "
+        "FROM branches WHERE name = ?",
+        (name,),
+    ).fetchone()
+    if not row:
+        return None
+    return {
+        "id": row[0],
+        "name": row[1],
+        "origin_event_id": row[2],
+        "head_event_id": row[3],
+        "chat_id": row[4],
+        "created_at": row[5],
+        "is_active": bool(row[6]),
+    }
+
+
+def list_branches(conn: Connection, chat_id: str | None = None) -> list[dict]:
+    if chat_id is None:
+        rows = conn.execute(
+            "SELECT id, name, origin_event_id, head_event_id, chat_id, "
+            "       created_at, is_active "
+            "FROM branches ORDER BY id ASC"
+        ).fetchall()
+    else:
+        rows = conn.execute(
+            "SELECT id, name, origin_event_id, head_event_id, chat_id, "
+            "       created_at, is_active "
+            "FROM branches WHERE chat_id = ? OR chat_id IS NULL "
+            "ORDER BY id ASC",
+            (chat_id,),
+        ).fetchall()
+    return [
+        {
+            "id": r[0],
+            "name": r[1],
+            "origin_event_id": r[2],
+            "head_event_id": r[3],
+            "chat_id": r[4],
+            "created_at": r[5],
+            "is_active": bool(r[6]),
+        }
+        for r in rows
+    ]
+
+
+def active_branch(conn: Connection) -> dict | None:
+    row = conn.execute(
+        "SELECT id, name, origin_event_id, head_event_id, chat_id, "
+        "       created_at, is_active "
+        "FROM branches WHERE is_active = 1"
+    ).fetchone()
+    if not row:
+        return None
+    return {
+        "id": row[0],
+        "name": row[1],
+        "origin_event_id": row[2],
+        "head_event_id": row[3],
+        "chat_id": row[4],
+        "created_at": row[5],
+        "is_active": bool(row[6]),
+    }
+
+
+__all__ = [
+    "get_branch",
+    "list_branches",
+    "active_branch",
+]

chat/state/embeddings.py

@@ -0,0 +1,105 @@
+"""Embeddings projector + readers (T88, Phase 4).
+
+Embeddings are stored as JSON-serialized float arrays in a regular
+SQLite table. Cosine similarity is computed in Python at query time
+(see chat/services/vector_search.py / T92). This deliberately avoids
+the sqlite-vec extension dependency — the host Python build doesn't
+support enable_load_extension. Phase 4.5+ may revisit if memory counts
+grow beyond pure-Python feasibility (~few thousand per query).
+"""
+
+from __future__ import annotations
+import json
+from sqlite3 import Connection
+
+from chat.eventlog.projector import on
+from chat.eventlog.log import Event
+
+
+@on("embedding_indexed")
+def _apply_embedding_indexed(conn: Connection, e: Event) -> None:
+    """Insert or replace the embedding for a memory.
+
+    Idempotent: re-projection or re-indexing replaces the prior vector.
+    """
+    p = e.payload
+    vector = p["vector"]
+    conn.execute(
+        "INSERT OR REPLACE INTO embeddings "
+        "(memory_id, vector_json, model, dim, indexed_at) "
+        "VALUES (?, ?, ?, ?, datetime('now'))",
+        (
+            int(p["memory_id"]),
+            json.dumps(list(vector)),
+            p["model"],
+            int(p.get("dim") or len(vector)),
+        ),
+    )
+
+
+@on("embedding_deindexed")
+def _apply_embedding_deindexed(conn: Connection, e: Event) -> None:
+    """Remove the embedding for a memory (used by reset cascade)."""
+    p = e.payload
+    conn.execute(
+        "DELETE FROM embeddings WHERE memory_id = ?",
+        (int(p["memory_id"]),),
+    )
+
+
+def get_embedding(conn: Connection, memory_id: int) -> dict | None:
+    row = conn.execute(
+        "SELECT memory_id, vector_json, model, dim, indexed_at "
+        "FROM embeddings WHERE memory_id = ?",
+        (memory_id,),
+    ).fetchone()
+    if not row:
+        return None
+    return {
+        "memory_id": row[0],
+        "vector": json.loads(row[1]),
+        "model": row[2],
+        "dim": row[3],
+        "indexed_at": row[4],
+    }
+
+
+def list_embeddings_for_owner(conn: Connection, owner_id: str) -> list[dict]:
+    """Return all embeddings for memories owned by ``owner_id``.
+
+    Used by vector search at query time (T92). The join carries the
+    fields the cosine ranker needs to assemble result rows without a
+    second round-trip: the POV summary text, significance, and witness
+    flags. The ``memories`` table has no separate ``text`` column —
+    ``pov_summary`` is the canonical narrative text per
+    ``chat/services/memory_write.py``.
+    """
+    rows = conn.execute(
+        "SELECT e.memory_id, e.vector_json, e.model, e.dim, "
+        "       m.pov_summary, m.significance, "
+        "       m.witness_you, m.witness_host, m.witness_guest "
+        "FROM embeddings e "
+        "JOIN memories m ON m.id = e.memory_id "
+        "WHERE m.owner_id = ?",
+        (owner_id,),
+    ).fetchall()
+    return [
+        {
+            "memory_id": r[0],
+            "vector": json.loads(r[1]),
+            "model": r[2],
+            "dim": r[3],
+            "pov_summary": r[4],
+            "significance": r[5],
+            "witness_you": r[6],
+            "witness_host": r[7],
+            "witness_guest": r[8],
+        }
+        for r in rows
+    ]
+
+
+__all__ = [
+    "get_embedding",
+    "list_embeddings_for_owner",
+]

chat/state/manual_edit.py

@@ -30,6 +30,20 @@ T72.3 adds a per-flag witness toggle:
   ``{"flag": "you"|"host"|"guest", "value": 0|1}`` and ``prior_value``
   mirrors the same shape so an inverse edit can restore the flag.
 
+T98.3 adds a hide-from-view toggle:
+- ``turn_hidden`` — flip ``event_log.hidden`` on a single turn row.
+  Hidden turns are filtered by ``read_recent_dialogue`` (see
+  :mod:`chat.services.turn_common`) so they vanish from the prompt
+  without being deleted from the log. ``target_id`` is the integer
+  ``event_log.id`` of the turn; ``new_value`` is ``{"hidden": 0|1}``
+  and ``prior_value`` mirrors the shape so an inverse edit restores it.
+
+T98.5 finishes the v1 drawer surface with two chat-scope text edits:
+- ``chat_narrative_anchor`` and ``chat_weather`` — string overwrites of
+  the matching ``chat_state`` columns. ``target_id`` is the chat id
+  (``chats.id``); ``new_value`` is the new string and ``prior_value``
+  carries the previous content for §6.4 reversibility.
+
 Pin toggles intentionally use the existing ``memory_pin_changed`` event
 (registered in :mod:`chat.state.memory`) rather than ``manual_edit`` so
 the projection writes both ``pinned`` and ``auto_pinned`` atomically.
@@ -138,5 +152,29 @@ def _apply_manual_edit(conn: Connection, e: Event) -> None:
                 f"UPDATE memories SET witness_{flag} = ? WHERE id = ?",
                 (1 if int(new_value["value"]) else 0, int(target_id)),
             )
+    elif kind == "turn_hidden":
+        # T98.3: hide-from-view toggle on a turn (event_log row). Sets
+        # ``event_log.hidden`` so :func:`read_recent_dialogue` (which
+        # filters ``hidden = 0``) drops the row from the prompt window
+        # without deleting it from the log. ``new_value`` is
+        # ``{"hidden": 0|1}``.
+        hidden_int = 1 if int(new_value.get("hidden", 0)) else 0
+        conn.execute(
+            "UPDATE event_log SET hidden = ? WHERE id = ?",
+            (hidden_int, int(target_id)),
+        )
+    elif kind == "chat_narrative_anchor":
+        # T98.5: string overwrite of ``chat_state.narrative_anchor`` for
+        # the chat keyed by ``target_id``.
+        conn.execute(
+            "UPDATE chat_state SET narrative_anchor = ? WHERE chat_id = ?",
+            (str(new_value), str(target_id)),
+        )
+    elif kind == "chat_weather":
+        # T98.5: string overwrite of ``chat_state.weather``.
+        conn.execute(
+            "UPDATE chat_state SET weather = ? WHERE chat_id = ?",
+            (str(new_value), str(target_id)),
+        )
     # Unknown target_kind: silently no-op for v1. Future kinds (activity
     # fields, etc.) extend the dispatch above.

chat/state/memory.py

@@ -102,6 +102,15 @@ _RECENCY_WEIGHT = 0.5
 # a higher-is-better score by a positive constant per the spec wording.
 SIGNIFICANCE_RANK_BIAS = 0.5
 
+# T96 (Phase 4): reciprocal-rank-fusion constant used when ``search_memories``
+# is given a ``query_vector`` and must merge FTS + vector candidate lists. The
+# value 60 is the canonical RRF constant from Cormack et al. ("Reciprocal Rank
+# Fusion outperforms Condorcet and Individual Rank Learning Methods", SIGIR
+# 2009): large enough to dampen the head of either ranking so that a strong
+# top-1 in ranking A doesn't crowd out a moderate top-3 in ranking B, but
+# small enough that the position-1/position-2 gap still matters.
+RRF_CONST = 60
+
 
 def search_memories(
     conn: Connection,
@@ -109,6 +118,8 @@ def search_memories(
     witness_role: str,
     query: str,
     k: int = 4,
+    *,
+    query_vector: list[float] | None = None,
 ) -> list[dict]:
     """FTS5 search over pov_summary, scoped by owner and witness role.
 
@@ -135,6 +146,23 @@ def search_memories(
     * **Python-side** — a composite re-rank with ``_SIGNIFICANCE_WEIGHT``
       reinforces the ordering after candidate retrieval, alongside the
       recency boost above.
+
+    PHASE 4 EXTENSION (T96): when ``query_vector`` is provided, fuses FTS and
+    vector hits via reciprocal-rank fusion (RRF):
+
+        fusion_score = 1/(RRF_CONST + fts_rank) + 1/(RRF_CONST + vec_rank)
+
+    where ``fts_rank`` and ``vec_rank`` are the 0-indexed positions of the
+    memory in each candidate list. Each candidate gets the sum of its
+    reciprocal ranks across both rankings; memories appearing in only one
+    ranking still get a partial score (the other term is dropped). Both
+    candidate lists are over-fetched at ``k * 2`` so a memory dominant in
+    only one channel has a fair chance to surface. The Python-side
+    significance + recency re-rank is then applied as a final pass to
+    break ties in favour of more important / more recent memories.
+
+    When ``query_vector`` is None: FTS-only behaviour unchanged — all
+    Phase 1-3.5 callers see the same row shape and ordering as before.
     """
     if witness_role not in _VALID_WITNESS_ROLES:
         raise ValueError(
@@ -148,7 +176,10 @@ def search_memories(
     select_list = ", ".join(f"m.{c}" for c in cols)
     # Over-fetch from FTS so the Python-side re-rank has room to reorder
     # results that BM25 alone would have demoted past the top-k boundary.
-    over_fetch = max(k * 4, 20)
+    # When fusing with a vector ranking, we still over-fetch (k*2 from each
+    # channel) so memories that are weak in FTS but strong in vector — and
+    # vice versa — make it into the merge pool.
+    over_fetch = max(k * 2, 20) if query_vector is not None else max(k * 4, 20)
     sql = (
         f"SELECT {select_list}, memories_fts.rank AS fts_rank "
         "FROM memories_fts "
@@ -165,11 +196,37 @@ def search_memories(
     )
     cur = conn.execute(sql, (owner_id, query, SIGNIFICANCE_RANK_BIAS, over_fetch))
     rows = cur.fetchall()
-    if not rows:
-        return []
 
-    # Recency normalises against the current max id for this owner so the
+    # FTS-only path: preserve pre-T96 behaviour exactly.
-    # boost magnitude is bounded regardless of dataset size.
+    if query_vector is None:
+        if not rows:
+            return []
+        return _composite_rerank(conn, cols, rows, owner_id, k)
+
+    # Fused path: combine FTS candidates with vector candidates via RRF.
+    return _rrf_fuse_and_rerank(
+        conn,
+        cols=cols,
+        fts_rows=rows,
+        owner_id=owner_id,
+        witness_role=witness_role,
+        query_vector=query_vector,
+        k=k,
+    )
+
+
+def _composite_rerank(
+    conn: Connection,
+    cols: list[str],
+    rows: list[tuple],
+    owner_id: str,
+    k: int,
+) -> list[dict]:
+    """Apply the significance + recency composite re-rank to FTS rows.
+
+    Extracted from ``search_memories`` so the no-vector path stays a single
+    call and the fused path can re-use the same boost formulae after RRF.
+    """
     max_id_row = conn.execute(
         "SELECT MAX(id) FROM memories WHERE owner_id = ?", (owner_id,)
     ).fetchone()
@@ -187,3 +244,129 @@ def search_memories(
 
     enriched.sort(key=lambda x: x["composite_score"])
     return enriched[:k]
+
+
+def _rrf_fuse_and_rerank(
+    conn: Connection,
+    *,
+    cols: list[str],
+    fts_rows: list[tuple],
+    owner_id: str,
+    witness_role: str,
+    query_vector: list[float],
+    k: int,
+) -> list[dict]:
+    """Merge FTS + vector candidates via reciprocal-rank fusion, then apply
+    the existing significance + recency boost as a final tie-breaker.
+
+    RRF formula (Cormack et al. 2009)::
+
+        fusion_score = sum over rankings r of  1 / (RRF_CONST + rank_r)
+
+    where ``rank_r`` is the 0-indexed position of the memory in ranking r.
+    "Missing from a ranking" is handled by SKIPPING the term for that
+    ranking — i.e. that channel contributes 0 to the sum, which preserves
+    the fairness property: a memory that only appears in one ranking is
+    not penalised relative to itself, just relative to memories that
+    appeared in both. This matches the canonical RRF presentation.
+
+    The final composite score subtracted from the *negated* fusion score
+    is::
+
+        composite = -fusion - sig_boost - recency_boost
+
+    Sorted ascending, smaller-is-better — the same ordering convention as
+    the FTS-only path so the Python-side significance + recency boosts
+    apply as a clean tie-breaker without inverting any sign.
+    """
+    # Lazy import to avoid a hard module-level cycle: vector_search reads
+    # from chat.state.embeddings, which is itself a sibling of this module.
+    from chat.services.vector_search import vector_search
+
+    fts_rank_by_id: dict[int, int] = {}
+    fts_row_by_id: dict[int, tuple] = {}
+    id_idx = cols.index("id")
+    for rank, row in enumerate(fts_rows):
+        memory_id = row[id_idx]
+        fts_rank_by_id[memory_id] = rank
+        fts_row_by_id[memory_id] = row
+
+    # Over-fetch the vector channel symmetrically so each channel gets a
+    # fair shot at surfacing its strongest candidates.
+    vec_over_fetch = max(k * 2, 20)
+    vec_hits = vector_search(
+        conn,
+        owner_id=owner_id,
+        witness_role=witness_role,
+        query_vector=query_vector,
+        k=vec_over_fetch,
+    )
+    vec_rank_by_id: dict[int, int] = {
+        hit["memory_id"]: rank for rank, hit in enumerate(vec_hits)
+    }
+
+    # If the vector channel returned nothing (no embeddings indexed), the
+    # fused path collapses cleanly to the FTS-only path. No error, no
+    # surprise zero-hit return.
+    if not vec_rank_by_id and not fts_row_by_id:
+        return []
+    if not vec_rank_by_id:
+        return _composite_rerank(conn, cols, fts_rows, owner_id, k)
+
+    # For any vector-only hits we don't have a full memory row for yet,
+    # fetch them in a single round-trip. The FTS row carries an ``fts_rank``
+    # column at the end; vector-only rows get ``None`` there.
+    missing_ids = [mid for mid in vec_rank_by_id if mid not in fts_row_by_id]
+    select_list = ", ".join(cols)
+    if missing_ids:
+        placeholders = ",".join("?" * len(missing_ids))
+        cur = conn.execute(
+            f"SELECT {select_list} FROM memories WHERE id IN ({placeholders})",
+            missing_ids,
+        )
+        for row in cur.fetchall():
+            # Pad with a None for the trailing ``fts_rank`` slot so the row
+            # shape matches FTS rows downstream.
+            fts_row_by_id[row[id_idx]] = tuple(row) + (None,)
+
+    # Compute fusion score per candidate. Missing-from-ranking terms are
+    # simply omitted from the sum.
+    all_ids = set(fts_rank_by_id) | set(vec_rank_by_id)
+    fusion_by_id: dict[int, float] = {}
+    for mid in all_ids:
+        score = 0.0
+        if mid in fts_rank_by_id:
+            score += 1.0 / (RRF_CONST + fts_rank_by_id[mid])
+        if mid in vec_rank_by_id:
+            score += 1.0 / (RRF_CONST + vec_rank_by_id[mid])
+        fusion_by_id[mid] = score
+
+    # Final composite re-rank: significance + recency boosts on top of the
+    # negated fusion score so the sort direction matches the FTS-only path.
+    max_id_row = conn.execute(
+        "SELECT MAX(id) FROM memories WHERE owner_id = ?", (owner_id,)
+    ).fetchone()
+    max_id = max_id_row[0] if max_id_row and max_id_row[0] else 1
+
+    result_cols = cols + ["fts_rank"]
+    enriched: list[dict] = []
+    for mid in all_ids:
+        row = fts_row_by_id.get(mid)
+        if row is None:
+            # Defensive: a vector hit with no memory row would be a logic
+            # bug (vector_search joins memories), so just skip it rather
+            # than crash the whole search.
+            continue
+        d = dict(zip(result_cols, row))
+        sig_boost = _SIGNIFICANCE_WEIGHT * (d.get("significance") or 0)
+        recency_boost = _RECENCY_WEIGHT * ((d.get("id") or 0) / max_id)
+        fusion = fusion_by_id[mid]
+        # Sort ascending, smaller-is-better → negate fusion so a larger
+        # fusion score yields a smaller composite. Significance and recency
+        # boosts then act as tie-breakers exactly like the FTS-only path.
+        d["fusion_score"] = fusion
+        d["composite_score"] = -fusion - sig_boost - recency_boost
+        enriched.append(d)
+
+    enriched.sort(key=lambda x: x["composite_score"])
+    return enriched[:k]

chat/templates/_drawer.html

@@ -16,6 +16,26 @@
       <p class="muted">No active container.</p>
     {% endif %}
     <p>Time: {{ chat.time }}</p>
+    <form class="inline-edit"
+          hx-post="/chats/{{ chat.id }}/drawer/chat/narrative-anchor"
+          hx-target="#drawer" hx-swap="innerHTML">
+      <label>
+        Narrative anchor:
+        <input type="text" name="new_value" maxlength="500"
+               value="{{ chat.narrative_anchor or '' }}">
+      </label>
+      <button type="submit">Save</button>
+    </form>
+    <form class="inline-edit"
+          hx-post="/chats/{{ chat.id }}/drawer/chat/weather"
+          hx-target="#drawer" hx-swap="innerHTML">
+      <label>
+        Weather:
+        <input type="text" name="new_value" maxlength="500"
+               value="{{ chat.weather or '' }}">
+      </label>
+      <button type="submit">Save</button>
+    </form>
     {% if scene %}
       <form class="inline-edit"
             hx-post="/chats/{{ chat.id }}/drawer/scene/close"
@@ -414,6 +434,121 @@
     {% endif %}
   </section>
 
+  <section class="drawer-section">
+    <h3>Branches</h3>
+    {% if branches %}
+      <ul class="branch-list">
+        {% for b in branches %}
+          <li class="branch-row{% if b.is_active %} branch-active{% endif %}">
+            <strong>{{ b.name }}</strong>
+            {% if b.is_active %}<span class="muted"> (active)</span>{% endif %}
+            <span class="muted"> &middot; {{ b.event_count }} events</span>
+            {% if not b.is_active %}
+              <form class="inline-edit"
+                    hx-post="/chats/{{ chat.id }}/drawer/branch/switch"
+                    hx-target="#drawer" hx-swap="innerHTML">
+                <input type="hidden" name="name" value="{{ b.name }}">
+                <button type="submit">Switch</button>
+              </form>
+            {% endif %}
+          </li>
+        {% endfor %}
+      </ul>
+    {% else %}
+      <p class="muted">No branches yet.</p>
+    {% endif %}
+    <details>
+      <summary>Create branch</summary>
+      <form class="inline-edit"
+            hx-post="/chats/{{ chat.id }}/drawer/branch/create"
+            hx-target="#drawer" hx-swap="innerHTML">
+        <label>
+          Name:
+          <input type="text" name="name" required
+                 placeholder="e.g. experiment_a">
+        </label>
+        <label>
+          Origin event id:
+          <input type="number" name="origin_event_id" required min="0">
+        </label>
+        <button type="submit">Create</button>
+      </form>
+    </details>
+  </section>
+
+  <section class="drawer-section">
+    <h3>Recent turns</h3>
+    {% if recent_turns %}
+      <ul class="recent-turns-list">
+        {% for t in recent_turns %}
+          <li class="turn-row{% if t.hidden %} turn-hidden{% endif %}">
+            <span class="muted">#{{ t.event_id }} {{ t.kind }}</span>
+            <strong>{{ t.speaker }}:</strong>
+            {{ t.excerpt }}{% if t.excerpt|length >= 120 %}…{% endif %}
+            <form class="inline-edit"
+                  hx-post="/chats/{{ chat.id }}/drawer/turn/hide/{{ t.event_id }}"
+                  hx-target="#drawer" hx-swap="innerHTML">
+              <input type="hidden" name="hidden" value="{{ 0 if t.hidden else 1 }}">
+              <label>
+                <input type="checkbox" {% if t.hidden %}checked{% endif %}
+                       onchange="this.form.requestSubmit()">
+                hide from view
+              </label>
+            </form>
+          </li>
+        {% endfor %}
+      </ul>
+    {% else %}
+      <p class="muted">No turns yet.</p>
+    {% endif %}
+  </section>
+
+  <section class="drawer-section">
+    <h3>Significance review</h3>
+    {% set total_mem = significance_distribution.values()|sum %}
+    {% if total_mem %}
+      <ul class="significance-distribution">
+        {% for level in [0, 1, 2, 3] %}
+          {% set count = significance_distribution[level] %}
+          {% set marker = ['·','•','★','★★'][level] %}
+          {% set pct = (100 * count / total_mem)|round(0, 'floor')|int if total_mem else 0 %}
+          <li class="sig-bar sig-{{ level }}">
+            <span class="sig-label">{{ marker }} ({{ level }})</span>
+            <span class="sig-bar-fill" style="width: {{ pct }}%"></span>
+            <span class="sig-count">{{ count }}</span>
+          </li>
+        {% endfor %}
+      </ul>
+    {% else %}
+      <p class="muted">No memories yet.</p>
+    {% endif %}
+    {% if recent_memories %}
+      <details>
+        <summary>Edit significance (recent memories)</summary>
+        <ul class="significance-edit-list">
+          {% for m in recent_memories %}
+            <li>
+              <span class="sig sig-{{ m.significance }}">{{ ['·','•','★','★★'][m.significance|default(0)] }}</span>
+              {{ m.pov_summary[:80] }}{% if m.pov_summary|length > 80 %}…{% endif %}
+              <form class="inline-edit"
+                    hx-post="/chats/{{ chat.id }}/drawer/memory/{{ m.id }}/significance"
+                    hx-target="#drawer" hx-swap="innerHTML">
+                <label>
+                  Significance:
+                  <input type="range" name="significance" min="0" max="3"
+                         value="{{ m.significance|default(0) }}"
+                         oninput="this.nextElementSibling.value = this.value">
+                  <output>{{ m.significance|default(0) }}</output>
+                </label>
+                <button type="submit">Save</button>
+              </form>
+            </li>
+          {% endfor %}
+        </ul>
+      </details>
+    {% endif %}
+  </section>
+
   <section class="drawer-section">
     <h3>Pinned memories ({{ pinned|length }} / {{ pin_cap }})</h3>
     {% if pinned %}

chat/templates/layout.html

@@ -5,8 +5,16 @@
   <ul>
     <li><a href="/chats" class="{% if active_nav == 'chats' %}active{% endif %}">Chats</a></li>
     <li><a href="/bots" class="{% if active_nav == 'bots' %}active{% endif %}">Bots</a></li>
+    <li><a href="/snapshots" class="{% if active_nav == 'snapshots' %}active{% endif %}">Snapshots</a></li>
     <li><a href="/settings" class="{% if active_nav == 'settings' %}active{% endif %}">Settings</a></li>
   </ul>
+  {# T100: cross-chat search box. GET /search so the URL is shareable
+     and back-button friendly; the results page itself re-renders this
+     form with the query pre-filled. #}
+  <form class="rail-search" action="/search" method="get" role="search">
+    <input type="search" name="q" placeholder="Search" aria-label="Search memories">
+    <button type="submit">Go</button>
+  </form>
 </nav>
 <main class="content">
   {% block content %}{% endblock %}

chat/templates/search.html

@@ -0,0 +1,37 @@
+{% extends "layout.html" %}
+{% block title %}Search - chat{% endblock %}
+{% block content %}
+<header class="page-header">
+  <h1>Search</h1>
+</header>
+
+<form class="search-page-form" action="/search" method="get">
+  <input type="text" name="q" value="{{ query|default('', true) }}"
+         placeholder="Search memories across all chats" autofocus>
+  <button type="submit">Search</button>
+</form>
+
+{% if not query %}
+  {# Empty-state placeholder: the top-bar form submits to /search even
+     with no input, so this page must render cleanly with no query. #}
+  <p class="muted search-empty">Enter a query to search memories across all chats.</p>
+{% elif not results %}
+  <p class="muted">No matches for &ldquo;{{ query }}&rdquo;.</p>
+{% else %}
+  <ul class="search-results">
+    {% for r in results %}
+    <li class="search-result">
+      <a class="search-result-link" href="/chats/{{ r.chat_id }}">
+        <div class="search-result-meta muted">
+          <strong>{{ r.owner_name }}</strong>
+          <span>&middot; {{ r.chat_id }}</span>
+          {% if r.chat_name %}<span>&middot; {{ r.chat_name }}</span>{% endif %}
+          {% if r.scene_label %}<span>&middot; scene {{ r.scene_label }}</span>{% endif %}
+        </div>
+        <div class="search-result-summary">{{ r.pov_summary }}</div>
+      </a>
+    </li>
+    {% endfor %}
+  </ul>
+{% endif %}
+{% endblock %}

chat/templates/snapshots.html

@@ -0,0 +1,66 @@
+{% extends "layout.html" %}
+{% block title %}Snapshots - chat{% endblock %}
+{% block content %}
+<header class="page-header">
+    <h1>Snapshots</h1>
+    <form method="post" action="/snapshots/take" class="inline-edit">
+        <button type="submit">Take snapshot now</button>
+    </form>
+</header>
+
+{% if preview %}
+<section class="snapshot-preview">
+    <h2>Preview: {{ preview.snapshot_id }}</h2>
+    <dl>
+        <dt>kind</dt><dd>{{ preview.kind }}</dd>
+        <dt>filename</dt><dd>{{ preview.filename }}</dd>
+        <dt>file size (bytes)</dt><dd>{{ preview.file_size_bytes }}</dd>
+        <dt>snapshot last_event_id</dt><dd>{{ preview.last_event_id }}</dd>
+        <dt>current event_log max id</dt><dd>{{ preview.current_event_log_max_id }}</dd>
+        <dt>events since snapshot</dt><dd>{{ preview.event_delta }}</dd>
+        <dt>events stored in snapshot</dt><dd>{{ preview.event_log_rows_in_snapshot }}</dd>
+    </dl>
+</section>
+{% endif %}
+
+{% if snapshots %}
+<table class="snapshot-list">
+    <thead>
+        <tr>
+            <th>ID</th>
+            <th>Kind</th>
+            <th>Created (UTC)</th>
+            <th>Size (bytes)</th>
+            <th>last_event_id</th>
+            <th>Actions</th>
+        </tr>
+    </thead>
+    <tbody>
+        {% for snap in snapshots %}
+        <tr>
+            <td>{{ snap.snapshot_id }}</td>
+            <td>{{ snap.kind }}</td>
+            <td>{{ snap.created_at }}</td>
+            <td>{{ snap.file_size_bytes }}</td>
+            <td>{{ snap.last_event_id if snap.last_event_id is not none else '?' }}</td>
+            <td>
+                <a href="/snapshots/{{ snap.snapshot_id }}/preview?kind={{ snap.kind }}">Preview</a>
+                <details class="snapshot-row-restore">
+                    <summary>Restore</summary>
+                    <form method="post" action="/snapshots/restore/{{ snap.snapshot_id }}" class="inline-edit">
+                        <input type="hidden" name="kind" value="{{ snap.kind }}">
+                        <label>Type "{{ snap.snapshot_id }}" to confirm:
+                            <input type="text" name="confirm_id" required>
+                        </label>
+                        <button type="submit">Restore from this snapshot</button>
+                    </form>
+                </details>
+            </td>
+        </tr>
+        {% endfor %}
+    </tbody>
+</table>
+{% else %}
+<p class="muted">No snapshots yet. Use "Take snapshot now" to create one.</p>
+{% endif %}
+{% endblock %}

chat/web/drawer.py

@@ -36,7 +36,14 @@ from fastapi.responses import HTMLResponse
 from fastapi.templating import Jinja2Templates
 
 from chat.eventlog.log import append_and_apply
+from chat.services.branching import (
+    branch_from_event,
+    list_branches_with_metadata,
+    switch_active_branch,
+)
+from chat.services.delete_impact import compute_delete_impact
 from chat.services.relationship_seed import seed_inter_bot_edges
+from chat.services.rewind import execute_rewind
 from chat.services.scene_summarize import apply_scene_close_summary
 from chat.state.edges import get_edge
 from chat.state.entities import get_bot, get_you, list_bots
@@ -169,6 +176,63 @@ async def drawer(chat_id: str, request: Request, conn=Depends(get_conn)):
     active_events = list_active_events(conn, chat_id)
     open_threads = list_open_threads(conn, chat_id)
 
+    # T98.3: recent turns (user_turn / assistant_turn) for the hide-from-view
+    # panel. Includes ``hidden`` rows so the user can un-hide them — the
+    # filter on the read side (read_recent_dialogue) is what drops hidden
+    # rows from the prompt; the drawer panel always shows everything.
+    turn_rows = conn.execute(
+        """
+        SELECT id, kind, payload_json, hidden
+        FROM event_log
+        WHERE kind IN ('user_turn', 'assistant_turn', 'user_turn_edit')
+          AND superseded_by IS NULL
+        ORDER BY id DESC
+        LIMIT ?
+        """,
+        (RECENT_LIMIT,),
+    ).fetchall()
+    recent_turns: list[dict] = []
+    for row in turn_rows:
+        try:
+            payload = json.loads(row[2]) if row[2] else {}
+        except (json.JSONDecodeError, TypeError):
+            payload = {}
+        if payload.get("chat_id") != chat_id:
+            continue
+        text = payload.get("prose") or payload.get("text") or ""
+        speaker = payload.get("speaker_id") or (
+            "you" if row[1].startswith("user") else "?"
+        )
+        recent_turns.append(
+            {
+                "event_id": int(row[0]),
+                "kind": row[1],
+                "speaker": speaker,
+                "excerpt": (text or "").replace("\n", " ")[:120],
+                "hidden": bool(row[3]),
+            }
+        )
+
+    # T98.1: branch metadata (every chat sees the global branch list — branches
+    # may be chat-scoped or global, so :func:`list_branches_with_metadata`
+    # returns both flavours and the template highlights the active one).
+    branches = list_branches_with_metadata(conn, chat_id)
+
+    # T98.2: significance distribution across this chat's memories. Powers
+    # the "Significance review" panel — a small histogram letting authors
+    # spot lopsided buckets (e.g. nothing significant=3 yet) and triage by
+    # editing individual memory significance values.
+    sig_rows = conn.execute(
+        "SELECT significance, COUNT(*) FROM memories "
+        "WHERE chat_id = ? GROUP BY significance ORDER BY significance",
+        (chat_id,),
+    ).fetchall()
+    significance_distribution = {int(r[0]): int(r[1]) for r in sig_rows}
+    # Ensure every bucket 0..3 is present so the bar-chart template can
+    # render a stable axis even when a level has zero rows.
+    for level in (0, 1, 2, 3):
+        significance_distribution.setdefault(level, 0)
+
     return TEMPLATES.TemplateResponse(
         request,
         "_drawer.html",
@@ -196,6 +260,9 @@ async def drawer(chat_id: str, request: Request, conn=Depends(get_conn)):
             "pin_cap": PIN_CAP,
             "active_events": active_events,
             "open_threads": open_threads,
+            "branches": branches,
+            "significance_distribution": significance_distribution,
+            "recent_turns": recent_turns,
         },
     )
 
@@ -993,6 +1060,7 @@ async def skip_elision(
             chat_id=chat_id,
             new_time=new_time,
             landing_state_hint=landing_state_hint,
+            app=request.app,
         )
     except ChatNotFoundError as exc:
         # Missing chat row: typed exception (T81) replaces the prior
@@ -1036,6 +1104,7 @@ async def skip_jump(
             new_time=new_time,
             notable_prose=notable_prose,
             reset_activity=reset_flag,
+            app=request.app,
         )
     except ChatNotFoundError as exc:
         # Missing chat row: typed exception (T81) replaces the prior
@@ -1078,3 +1147,332 @@ async def close_thread(
         },
     )
     return await drawer(chat_id, request, conn)
+
+
+# --- T98.1 branching UI --------------------------------------------------
+#
+# Three POST endpoints wired to the Phase 4 :mod:`chat.services.branching`
+# helpers. The drawer's "Branches" panel exposes:
+#
+# * Create from a free-form ``origin_event_id``.
+# * Switch the active branch by name.
+# * Convenience "branch from this turn" against a per-turn event_id (the
+#   chat surface stamps ``id="turn-<event_id>"`` on every turn so users can
+#   pick the right one without copying ids by hand).
+#
+# All three return the refreshed drawer partial; failures from the service
+# layer (duplicate name, unknown branch, invalid origin) surface as 400 so
+# HTMX displays the inline error.
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/branch/create",
+    response_class=HTMLResponse,
+)
+async def create_branch(
+    chat_id: str,
+    request: Request,
+    name: str = Form(...),
+    origin_event_id: int = Form(...),
+    conn=Depends(get_conn),
+):
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+    try:
+        branch_from_event(
+            conn,
+            name=name,
+            origin_event_id=int(origin_event_id),
+            chat_id=chat_id,
+        )
+    except ValueError as exc:
+        raise HTTPException(status_code=400, detail=str(exc))
+    return await drawer(chat_id, request, conn)
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/branch/switch",
+    response_class=HTMLResponse,
+)
+async def switch_branch(
+    chat_id: str,
+    request: Request,
+    name: str = Form(...),
+    conn=Depends(get_conn),
+):
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+    try:
+        switch_active_branch(conn, name=name)
+    except ValueError as exc:
+        raise HTTPException(status_code=400, detail=str(exc))
+    return await drawer(chat_id, request, conn)
+
+
+@router.get(
+    "/chats/{chat_id}/drawer/turn/delete-preview/{event_id}",
+    response_class=HTMLResponse,
+)
+async def delete_preview(
+    chat_id: str,
+    event_id: int,
+    request: Request,
+    conn=Depends(get_conn),
+):
+    """Render an :class:`ImpactReport` for ``event_id`` as a small modal.
+
+    Read-only — :func:`compute_delete_impact` does not mutate the
+    database. The modal contains a confirmation form posting to
+    :func:`delete_turn` below; HTMX swaps the fragment into a modal
+    target on the chat page.
+    """
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+
+    report = compute_delete_impact(conn, target_event_id=int(event_id))
+
+    # Build the modal HTML directly — the impact report is small and
+    # reusing the drawer template would require a fragment include just
+    # for this surface. Mirrors the rewind-preview style in
+    # :func:`chat.web.turns.rewind_preview`.
+    items_html = "".join(
+        f"<li><strong>{item.kind}</strong>: {item.description}</li>"
+        for item in report.cascading
+    )
+    notes_html = "".join(f"<li>{note}</li>" for note in report.notes)
+    body = (
+        "<div class='delete-impact-modal'>"
+        f"<h3>Delete event {report.target_event_id}?</h3>"
+        f"<p>This will discard {len(report.cascading)} events. Cascade:</p>"
+        f"<ul class='delete-impact-cascade'>{items_html or '<li>none</li>'}</ul>"
+        f"<ul class='delete-impact-notes'>{notes_html}</ul>"
+        f"<form hx-post='/chats/{chat_id}/drawer/turn/delete/{report.target_event_id}' "
+        "hx-target='#drawer' hx-swap='innerHTML'>"
+        "<button type='submit'>Confirm delete</button>"
+        "</form>"
+        "</div>"
+    )
+    return HTMLResponse(body)
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/turn/delete/{event_id}",
+    response_class=HTMLResponse,
+)
+async def delete_turn(
+    chat_id: str,
+    event_id: int,
+    request: Request,
+    conn=Depends(get_conn),
+):
+    """Delete a turn (and everything after) by invoking the existing rewind path.
+
+    The :func:`chat.services.rewind.execute_rewind` API takes
+    ``after_event_id``: it removes events with id strictly greater than
+    that argument. To make ``event_id`` itself disappear we pass
+    ``after_event_id = event_id - 1`` — a thin adapter, not a
+    re-implementation of rewind.
+
+    A snapshot is taken before truncation (inside ``execute_rewind``)
+    so the user can recover via the snapshot index.
+    """
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+
+    settings = request.app.state.settings
+    execute_rewind(
+        db_path=settings.db_path,
+        data_dir=settings.data_dir,
+        after_event_id=int(event_id) - 1,
+    )
+    # ``conn`` is now stale (the rewind opened its own connection and
+    # truncated/reprojected). Re-render the drawer through a fresh open
+    # so the partial reflects the truncated state.
+    from chat.db.connection import open_db
+
+    with open_db(settings.db_path) as fresh:
+        return await drawer(chat_id, request, fresh)
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/turn/hide/{event_id}",
+    response_class=HTMLResponse,
+)
+async def hide_turn(
+    chat_id: str,
+    event_id: int,
+    request: Request,
+    hidden: int = Form(...),
+    conn=Depends(get_conn),
+):
+    """Toggle ``event_log.hidden`` on a turn via the ``turn_hidden``
+    ``manual_edit`` projector branch.
+
+    The route validates the target is an actual turn-shaped row in this
+    chat (so a stray click on the chat panel can't hide a system event)
+    and snapshots the prior ``hidden`` value for §6.4 reversibility.
+    """
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+
+    row = conn.execute(
+        "SELECT kind, payload_json, hidden FROM event_log WHERE id = ?",
+        (int(event_id),),
+    ).fetchone()
+    if row is None:
+        raise HTTPException(
+            status_code=404, detail=f"event not found: {event_id}"
+        )
+    if row[0] not in ("user_turn", "assistant_turn", "user_turn_edit"):
+        raise HTTPException(
+            status_code=400,
+            detail=f"event {event_id} is not a turn (kind={row[0]})",
+        )
+    try:
+        payload = json.loads(row[1]) if row[1] else {}
+    except (json.JSONDecodeError, TypeError):
+        payload = {}
+    if payload.get("chat_id") != chat_id:
+        raise HTTPException(
+            status_code=404,
+            detail=f"event {event_id} not in chat {chat_id}",
+        )
+
+    prior_hidden = 1 if int(row[2]) else 0
+    new_hidden = 1 if int(hidden) else 0
+    append_and_apply(
+        conn,
+        kind="manual_edit",
+        payload={
+            "target_kind": "turn_hidden",
+            "target_id": int(event_id),
+            "prior_value": {"hidden": prior_hidden},
+            "new_value": {"hidden": new_hidden},
+        },
+    )
+    return await drawer(chat_id, request, conn)
+
+
+# --- T98.5 chat narrative anchor + weather ----------------------------
+#
+# Audit (T98.5) found two §6.4 fields without drawer affordances despite
+# both being prose strings stored on ``chat_state``: ``narrative_anchor``
+# (the "Day 1" / "morning of the gala" hint above the chat clock) and
+# ``weather``. Both land via the existing ``manual_edit`` projector with
+# new branches added in :mod:`chat.state.manual_edit`. The container
+# ``properties_json`` blob is more invasive — bounded JSON edits aren't
+# wired through manual_edit and the drawer never surfaces multiple
+# containers at once, so it stays out of v1.
+
+CHAT_NARRATIVE_ANCHOR_MAX = 500
+CHAT_WEATHER_MAX = 500
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/chat/narrative-anchor",
+    response_class=HTMLResponse,
+)
+async def edit_chat_narrative_anchor(
+    chat_id: str,
+    request: Request,
+    new_value: str = Form(...),
+    conn=Depends(get_conn),
+):
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+    if len(new_value) > CHAT_NARRATIVE_ANCHOR_MAX:
+        raise HTTPException(
+            status_code=400,
+            detail=(
+                f"narrative_anchor exceeds {CHAT_NARRATIVE_ANCHOR_MAX} chars "
+                f"(got {len(new_value)})"
+            ),
+        )
+
+    prior = chat.get("narrative_anchor") or ""
+    append_and_apply(
+        conn,
+        kind="manual_edit",
+        payload={
+            "target_kind": "chat_narrative_anchor",
+            "target_id": chat_id,
+            "prior_value": prior,
+            "new_value": new_value,
+        },
+    )
+    return await drawer(chat_id, request, conn)
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/chat/weather",
+    response_class=HTMLResponse,
+)
+async def edit_chat_weather(
+    chat_id: str,
+    request: Request,
+    new_value: str = Form(...),
+    conn=Depends(get_conn),
+):
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+    if len(new_value) > CHAT_WEATHER_MAX:
+        raise HTTPException(
+            status_code=400,
+            detail=(
+                f"weather exceeds {CHAT_WEATHER_MAX} chars "
+                f"(got {len(new_value)})"
+            ),
+        )
+
+    prior = chat.get("weather") or ""
+    append_and_apply(
+        conn,
+        kind="manual_edit",
+        payload={
+            "target_kind": "chat_weather",
+            "target_id": chat_id,
+            "prior_value": prior,
+            "new_value": new_value,
+        },
+    )
+    return await drawer(chat_id, request, conn)
+
+
+@router.post(
+    "/chats/{chat_id}/drawer/branch/from-turn/{event_id}",
+    response_class=HTMLResponse,
+)
+async def branch_from_turn(
+    chat_id: str,
+    event_id: int,
+    request: Request,
+    name: str = Form(...),
+    conn=Depends(get_conn),
+):
+    """Convenience: branch from a specific turn event.
+
+    Identical to :func:`create_branch` except ``origin_event_id`` is
+    encoded in the URL — the chat surface renders one such form per turn
+    so users can fork mid-conversation without authoring an event id by
+    hand.
+    """
+    chat = get_chat(conn, chat_id)
+    if chat is None:
+        raise HTTPException(status_code=404, detail=f"chat not found: {chat_id}")
+    try:
+        branch_from_event(
+            conn,
+            name=name,
+            origin_event_id=int(event_id),
+            chat_id=chat_id,
+        )
+    except ValueError as exc:
+        raise HTTPException(status_code=400, detail=str(exc))
+    return await drawer(chat_id, request, conn)

chat/web/meanwhile.py

@@ -131,6 +131,7 @@ async def process_meanwhile_turn(
     *,
     chat_id: str,
     prose: str,
+    app=None,
 ) -> dict:
     """Run one meanwhile turn end-to-end.
 
@@ -314,6 +315,7 @@ async def process_meanwhile_turn(
             narrative_text=text,
             scene_id=scene_id,
             chat_clock_at=chat.get("time"),
+            app=app,
         )
 
         # 9. Post-turn state-update — exactly 2 directed pairs over the

chat/web/search.py

@@ -0,0 +1,92 @@
+"""T100 (Phase 4): cross-chat search UX route.
+
+Wraps T93's :func:`chat.services.cross_chat_search.search_all_memories`
+in a small read-only HTML surface so the top-bar search input has
+somewhere to land. The route does no filtering of its own beyond the
+empty-query fast-path that T93 already implements; ranking, owner
+scope, and witness scope all live in the service layer.
+
+For each match we hydrate just enough metadata to render a row:
+* the owner bot's display name (so users see "BOTA" not "bot_a"),
+* the originating ``chat_id`` (the link target — there's no per-turn
+  anchor today because memories don't carry an ``event_id`` column,
+  so we deep-link to the chat as a whole),
+* the originating scene title when one exists,
+* and the ``pov_summary`` itself.
+
+We deliberately keep this module synchronous and template-only — no
+HTMX swaps, no JSON API — because the search box is a "leave the
+current chat to look something up" surface, not an inline drawer.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse
+from fastapi.templating import Jinja2Templates
+
+from chat.services.cross_chat_search import search_all_memories
+from chat.state.entities import get_bot
+from chat.state.world import get_chat, get_scene
+from chat.web.bots import get_conn
+
+TEMPLATES = Jinja2Templates(
+    directory=str(Path(__file__).resolve().parent.parent / "templates")
+)
+
+router = APIRouter()
+
+
+@router.get("/search", response_class=HTMLResponse)
+async def search(request: Request, q: str = "", conn=Depends(get_conn)):
+    """Render ``search.html`` with up to 50 cross-chat FTS matches.
+
+    ``q`` is intentionally allowed to be empty — that path renders the
+    page's "enter a query" placeholder rather than a 400, because the
+    top-bar form submits to this URL even with an empty input. T93's
+    service short-circuits whitespace-only queries to ``[]`` so there
+    is no FTS5 ``MATCH ''`` syntax error to guard against here.
+    """
+    raw_results = search_all_memories(conn, query=q, k=50) if q else []
+
+    # Hydrate display fields per row. We do this in the route (not the
+    # service) so the service stays a pure FTS shim that other UIs
+    # can reuse.
+    results = []
+    for row in raw_results:
+        bot = get_bot(conn, row["owner_id"])
+        chat = get_chat(conn, row["chat_id"])
+        scene = get_scene(conn, row["scene_id"]) if row["scene_id"] else None
+        results.append(
+            {
+                "memory_id": row["memory_id"],
+                "owner_id": row["owner_id"],
+                "owner_name": bot["name"] if bot else row["owner_id"],
+                "chat_id": row["chat_id"],
+                "chat_name": (
+                    chat.get("narrative_anchor") if chat else None
+                ),
+                "scene_id": row["scene_id"],
+                # Scenes have no ``title`` column today; surface the
+                # ``started_at`` timestamp as a human-friendly label
+                # when a scene is set, otherwise leave it blank.
+                "scene_label": (
+                    scene.get("started_at") if scene else None
+                ),
+                "pov_summary": row["pov_summary"],
+                "significance": row["significance"],
+                "ts": row["ts"],
+            }
+        )
+
+    return TEMPLATES.TemplateResponse(
+        request,
+        "search.html",
+        {
+            "query": q,
+            "results": results,
+            "active_nav": "search",
+        },
+    )

chat/web/skip.py

@@ -91,6 +91,7 @@ async def process_elision_skip(
     chat_id: str,
     new_time: str,
     landing_state_hint: str = "",
+    app=None,
 ) -> dict:
     """Run an elision skip end-to-end.
 
@@ -175,6 +176,7 @@ async def process_jump_skip(
     new_time: str,
     notable_prose: str = "",
     reset_activity: bool = False,
+    app=None,
 ) -> dict:
     """Run a jump skip end-to-end.
 
@@ -254,6 +256,7 @@ async def process_jump_skip(
                     chat_clock_at=new_time,
                     source="synthesized",
                     significance=mem.significance,
+                    app=app,
                 )
 
     narration = await narrate_skip(

chat/web/snapshots.py

@@ -0,0 +1,190 @@
+"""Snapshot UX routes (T99).
+
+Surfaces the existing snapshot service (``chat/services/snapshot.py``)
+through HTML so the user can see, take, restore, and preview snapshots
+without dropping to a shell.
+
+Routes:
+
+* ``GET  /snapshots``                    list all snapshots (both kinds)
+* ``POST /snapshots/take``               take a periodic snapshot now
+* ``POST /snapshots/restore/{id}``       restore (requires matching ``confirm_id``)
+* ``GET  /snapshots/{id}/preview``       show metadata + delta vs current
+
+The ``snapshot_id`` is the filename stem (the UTC timestamp written by
+:func:`chat.services.snapshot.take_snapshot`) — there's no separate UUID,
+and the timestamp filename is already unique per snapshot kind. Both
+periodic and rewind snapshots share the same id space lookup-wise, so
+the restore + preview routes accept ``kind`` as a form/query param to
+disambiguate.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from fastapi import APIRouter, Depends, Form, HTTPException, Request
+from fastapi.responses import HTMLResponse, RedirectResponse
+from fastapi.templating import Jinja2Templates
+
+from chat.services.snapshot import (
+    restore_from_snapshot,
+    take_snapshot,
+)
+from chat.web.bots import get_conn
+
+TEMPLATES = Jinja2Templates(
+    directory=str(Path(__file__).resolve().parent.parent / "templates")
+)
+
+router = APIRouter()
+
+SNAPSHOT_KINDS = ("periodic", "rewind")
+
+
+def _list_all_snapshots(data_dir: Path) -> list[dict]:
+    """Walk ``data/snapshots/{kind}/`` for both kinds and collect metadata.
+
+    Each entry exposes the fields the template needs: ``snapshot_id``
+    (filename stem), ``kind``, ``created_at`` (file mtime as ISO), the
+    on-disk ``file_size_bytes``, and the snapshot's stored
+    ``last_event_id`` (parsed from the JSON body — small enough that
+    listing isn't a performance concern for the handful of files we keep).
+    """
+    from datetime import datetime, timezone
+
+    rows: list[dict] = []
+    for kind in SNAPSHOT_KINDS:
+        snap_dir = data_dir / "snapshots" / kind
+        if not snap_dir.exists():
+            continue
+        for path in sorted(snap_dir.glob("*.json")):
+            try:
+                dump = json.loads(path.read_text())
+                last_event_id = dump.get("last_event_id", 0)
+            except (OSError, json.JSONDecodeError):
+                # Corrupt or unreadable files still get listed so the
+                # user can see and delete them; just don't crash here.
+                last_event_id = None
+            stat = path.stat()
+            rows.append(
+                {
+                    "snapshot_id": path.stem,
+                    "kind": kind,
+                    "created_at": datetime.fromtimestamp(
+                        stat.st_mtime, tz=timezone.utc
+                    ).isoformat(),
+                    "file_size_bytes": stat.st_size,
+                    "last_event_id": last_event_id,
+                    "filename": path.name,
+                }
+            )
+    # Newest first for display.
+    rows.sort(key=lambda r: r["created_at"], reverse=True)
+    return rows
+
+
+def _resolve_snapshot_path(
+    data_dir: Path, snapshot_id: str, kind: str
+) -> Path:
+    """Map an ``(id, kind)`` pair to the on-disk file, or 404."""
+    if kind not in SNAPSHOT_KINDS:
+        raise HTTPException(status_code=400, detail=f"unknown kind: {kind}")
+    path = data_dir / "snapshots" / kind / f"{snapshot_id}.json"
+    if not path.exists():
+        raise HTTPException(status_code=404, detail="snapshot not found")
+    return path
+
+
+@router.get("/snapshots", response_class=HTMLResponse)
+async def snapshots_list(request: Request):
+    settings = request.app.state.settings
+    rows = _list_all_snapshots(settings.data_dir)
+    return TEMPLATES.TemplateResponse(
+        request,
+        "snapshots.html",
+        {"snapshots": rows, "active_nav": "snapshots"},
+    )
+
+
+@router.post("/snapshots/take")
+async def snapshots_take(request: Request, conn=Depends(get_conn)):
+    """Take a periodic snapshot now.
+
+    We use ``kind="periodic"`` for manual snapshots since they're
+    user-initiated checkpoints, not pre-rewind safety dumps. They count
+    against the 5-snapshot retention but that's fine — manual ones are
+    the most recent so they're the last to be pruned.
+    """
+    settings = request.app.state.settings
+    take_snapshot(conn, data_dir=settings.data_dir, kind="periodic")
+    return RedirectResponse(url="/snapshots", status_code=303)
+
+
+@router.post("/snapshots/restore/{snapshot_id}")
+async def snapshots_restore(
+    snapshot_id: str,
+    request: Request,
+    confirm_id: str = Form(""),
+    kind: str = Form("periodic"),
+    conn=Depends(get_conn),
+):
+    """Hard-confirm restore: ``confirm_id`` must equal the path id.
+
+    Mismatched confirm → 400 (without touching the DB). On match, the
+    existing :func:`restore_from_snapshot` clears projected tables and
+    re-loads them from the dump.
+    """
+    if confirm_id != snapshot_id:
+        raise HTTPException(
+            status_code=400,
+            detail="confirm_id does not match snapshot id",
+        )
+    settings = request.app.state.settings
+    path = _resolve_snapshot_path(settings.data_dir, snapshot_id, kind)
+    restore_from_snapshot(conn, path)
+    return RedirectResponse(url="/snapshots", status_code=303)
+
+
+@router.get("/snapshots/{snapshot_id}/preview", response_class=HTMLResponse)
+async def snapshots_preview(
+    snapshot_id: str,
+    request: Request,
+    kind: str = "periodic",
+    conn=Depends(get_conn),
+):
+    """Show snapshot metadata + a basic delta against the current event log.
+
+    Phase 4 keeps this simple: the snapshot's ``last_event_id`` plus the
+    current ``MAX(event_log.id)`` is enough to tell the user how far the
+    log has moved on. A richer per-table diff is a Phase 4.5+ concern.
+    """
+    settings = request.app.state.settings
+    path = _resolve_snapshot_path(settings.data_dir, snapshot_id, kind)
+    dump = json.loads(path.read_text())
+    last_event_id = dump.get("last_event_id", 0)
+
+    cur = conn.execute("SELECT MAX(id) FROM event_log")
+    row = cur.fetchone()
+    current_max_id = row[0] if row[0] is not None else 0
+
+    stat = path.stat()
+    return TEMPLATES.TemplateResponse(
+        request,
+        "snapshots.html",
+        {
+            "snapshots": _list_all_snapshots(settings.data_dir),
+            "active_nav": "snapshots",
+            "preview": {
+                "snapshot_id": snapshot_id,
+                "kind": kind,
+                "filename": path.name,
+                "file_size_bytes": stat.st_size,
+                "last_event_id": last_event_id,
+                "current_event_log_max_id": current_max_id,
+                "event_delta": current_max_id - last_event_id,
+                "event_log_rows_in_snapshot": len(dump.get("event_log", [])),
+            },
+        },
+    )

chat/web/turns.py

@@ -248,6 +248,7 @@ async def post_turn(
                 settings,
                 chat_id=chat_id,
                 prose=prose,
+                app=request.app,
             )
         except ValueError as exc:
             raise HTTPException(status_code=400, detail=str(exc))
@@ -352,6 +353,7 @@ async def post_turn(
                 new_time=new_time,
                 landing_state_hint=getattr(parsed, "landing_state_hint", "")
                 or "",
+                app=request.app,
             )
         except ChatNotFoundError as exc:
             # Defensive: chat existence is checked above, so this only
@@ -512,6 +514,7 @@ async def post_turn(
         narrative_text=primary_text,
         scene_id=scene["id"] if scene else None,
         chat_clock_at=chat.get("time"),
+        app=request.app,
     )
 
     # 7b. Post-turn state-update pass (Requirements §3.4 / T40). All
@@ -746,6 +749,7 @@ async def post_turn(
                     narrative_text=interjection_text,
                     scene_id=scene["id"] if scene else None,
                     chat_clock_at=chat.get("time"),
+                    app=request.app,
                 )
 
                 # T74.2: enqueue a significance pass for the interjection
@@ -1092,6 +1096,7 @@ async def regenerate_turn(
             chat_id=chat_id,
             original_assistant_event_id=event_id,
             edited_user_prose=edited_prose,
+            app=request.app,
         )
     except ValueError as e:
         raise HTTPException(status_code=404, detail=str(e))

docs/plans/2026-04-26-v1-requirements-design.md

@@ -520,6 +520,8 @@ Written per witness when a scene closes. Different details, different interpreta
 
 ### Phase 4 — polish
 
+**Status: shipped 2026-04-27** (T88–T102, 15 tasks across 8 waves; +70 tests). See "Phase 4 status" in CLAUDE.md for the per-task breakdown. Vector retrieval shipped via pure-Python cosine over a JSON-blob embeddings table (sqlite-vec deferred — host Python lacks loadable extensions); branching is data-model + drawer UI; significance review, hide-from-view soft delete, surgical delete with cascade preview, snapshot UX, and cross-chat search all surface from the drawer or top-bar.
+
 - Vector retrieval (sqlite-vss or sqlite-vec).
 - Branching UI.
 - Drawer-edit on every field.

docs/plans/2026-04-27-v4-phase4-implementation.md

@@ -0,0 +1,832 @@
+# Roleplay Engine — Phase 4 Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use `superpowers-extended-cc:executing-plans` to implement this plan task-by-task. Use the parallel-dispatch pattern documented under "Parallel-Execution Strategy" for parallel waves.
+
+**Goal:** Land Phase 4 polish per requirements doc §13 + §14: vector retrieval, branching UI, drawer-edit on every field, backup tooling, significance review UI, surgical delete with cascade preview, hide-from-view soft delete, plus cross-chat search and the small Phase 3.6 carry-over fixes.
+
+**Architecture:** Builds on Phase 3.5's stable base. Two new tables (`embeddings`, `branches`) and one external dependency (sqlite-vec extension). Embedding generation runs as a deferred async job — NOT inline with turns — so the play loop stays fast even when the embedding endpoint is slow. Branching is data-model-only at first (events + selectors); UI grafts on top. Surgical delete + cascade preview reuses the existing rewind-and-supersede plumbing. Cross-chat search piggybacks on the existing FTS5 + (now) vector retrieval.
+
+**Tech Stack:**
+
+- **NEW dependency: `sqlite-vec`** (or `sqlite-vss` — Phase 4 picks; recommended `sqlite-vec` for simpler load semantics and active maintenance). Add to `pyproject.toml`.
+- **Embedding model selection** is part of T91 spec. Recommended default: a small model on Featherless (e.g., `BAAI/bge-small-en-v1.5` if available) or a local CPU-friendly model via `sentence-transformers`. Document choice in CLAUDE.md.
+- Same as Phase 3 otherwise (Python 3.11+, FastAPI, HTMX, SQLite).
+
+**Source-of-truth references:**
+
+- Phase 4 scope: requirements doc §13 "Phase 4 — polish" + §14 "Open / Deferred Decisions".
+- Behavioral details: §6 (prompt assembly + retrieval), §10 (rewind / regenerate / reset), §11 (compression + significance), §12 (snapshots).
+- Conventions: [`CLAUDE.md`](../../CLAUDE.md) §"Behavioral defaults" + §"Phase 3 status" + §"Phase 3.5 status".
+- Phase 3.5 cleanup plan (style, file-bundling pattern): [2026-04-26-v3.5-phase3.5-cleanup.md](2026-04-26-v3.5-phase3.5-cleanup.md).
+
+---
+
+## Pre-flight
+
+**Branch:** create `phase-4` from the latest `main` after Phase 3.5 has merged (it has — main is at `1b66a28`):
+
+```bash
+git checkout main && git pull && git checkout -b phase-4
+```
+
+**Schema baseline:** Phase 3.5 leaves the DB at version 11. Phase 4 adds two migrations: `0012_embeddings.sql` and `0013_branches.sql`. Final schema version: 13.
+
+**External dependency setup (BEFORE T88 dispatch):**
+
+The controlling agent should add `sqlite-vec` to `pyproject.toml` and run `pip install -e .` (or equivalent) so all worktrees pick up the new dependency. Confirm `sqlite_vec` imports cleanly:
+
+```bash
+python -c "import sqlite_vec; print(sqlite_vec.__version__)"
+```
+
+If `sqlite_vec` isn't on PyPI when this plan executes, fall back to `sqlite-vss` and adapt T88/T92 accordingly. Both expose vector-search SQL via a loadable extension.
+
+**Pinned non-negotiables (carried forward):**
+
+- State changes go through the event log. Use `append_and_apply(conn, kind, payload)` for the live path; `apply_event` only after a fresh `append_event` returning the new id.
+- Witness filter every memory read at SQL level (hard `WHERE` constraint; never a soft signal).
+- Per-POV scene summaries — never write omniscient narration.
+- TDD: every task starts with a failing test (or a regression test pinning existing contract before refactor).
+- One commit per task minimum. Tasks that bundle multiple sub-features SHOULD split commits internally.
+
+**Verification before claiming done:** Use `superpowers-extended-cc:verification-before-completion` — run the test command, paste actual output. Don't assume green.
+
+---
+
+## Phase 3.6 carry-overs folded in
+
+Three small items from Phase 3.6 backlog are bundled into Phase 4's Wave 1 trivial-fixes task (T90):
+
+1. `read_recent_dialogue` chat-id pushdown into SQL (T80 review nit)
+2. Lifecycle warning wording in regenerate (T83.4 — "at-or-after turn X" tightening)
+3. Legacy single-bot `record_turn_memory` consolidation (T84 review nit)
+
+Three items remain DEFERRED beyond Phase 4 (Phase 4.5 if needed):
+
+- Scene-close-on-cancel UX revisit (no action unless real play surfaces a regression).
+- Cross-feature canned-queue brittleness (structured fixture builder for tests — not blocking).
+- Full lifecycle-rollback in regenerate (warning log already shipped in T83.4; proper rollback needs schema-level back-references, deferred indefinitely).
+
+---
+
+## Parallel-Execution Strategy
+
+Same pattern as Phase 3.5. Eight waves: parallel within each wave (file-disjoint), serial across waves.
+
+### How to dispatch a wave in parallel
+
+Use the **Agent tool with `isolation: "worktree"`** so each subagent gets its own git worktree. (If the controlling session's working directory is **not** the chat repo, create worktrees manually with `git worktree add .worktrees/<wave>-<task> -b <wave>/<task> phase-4` from inside the chat repo.)
+
+Dispatch all tasks in a wave in a single message:
+
+```
+Agent({ description: "Wave 1 — T88 embeddings table", prompt: "...", isolation: "worktree" })
+Agent({ description: "Wave 1 — T89 branches table", ... })
+Agent({ description: "Wave 1 — T90 phase 3.6 carry-overs", ... })
+```
+
+### After a wave completes
+
+1. Each subagent returns its worktree path and commit SHA(s).
+2. **Run a spec + code-quality reviewer subagent on each completed task.** Combined review acceptable for trivial tasks (T90 carry-overs); separate spec + quality reviewers for vector-retrieval tasks (T91, T92, T96, T97) since the integration surface is wider.
+3. **Merge the wave into `phase-4`** in any order (file-disjointness guarantees no conflict). Use `--no-ff`.
+4. **Run the full test suite** on the merged `phase-4`. If red, the wave's mutual-independence assumption was violated — bisect, fix, re-merge.
+5. **Push `phase-4`** to gitea.
+6. Optionally clean up worktrees.
+
+### Conflict prevention checklist
+
+For each parallel wave, verify the **Files** sections of all tasks have **no overlapping paths**. Hot files in this plan: `chat/web/drawer.py` + `chat/templates/_drawer.html` (T98 only — bundled), `chat/state/memory.py` (T96 only), `chat/services/memory_write.py` (T90 + T97 — sequential), `chat/web/turns.py` (T98 only via delete affordance — sequential after T96).
+
+### Why each wave is parallel-safe
+
+| Wave | Tasks | Hot files touched | Disjoint? |
+|------|-------|-------------------|-----------|
+| 1 | T88, T89, T90 | new migrations + new state modules; T90 touches `turn_common.py` + `regenerate.py` + `memory_write.py` (additive only) | ✅ |
+| 2 | T91, T92, T93 | new service modules (embeddings, vector_search, cross_chat_search) | ✅ |
+| 3 | T94, T95 | new service modules (branching, delete_impact) | ✅ |
+| 4 | T96 | `chat/state/memory.py` (combined retrieval ranking) | (single task) |
+| 5 | T97 | `chat/services/memory_write.py` + new backfill script | (single task) |
+| 6 | T98 | `chat/web/drawer.py` + `chat/templates/_drawer.html` (drawer Phase 4 bundle) | (single task) |
+| 7 | T99, T100 | new files: `chat/web/snapshots.py` + `chat/templates/snapshots.html` (T99); `chat/web/search.py` + `chat/templates/search.html` + small chat.html top-bar addition (T100) | ✅ (disjoint) |
+| 8 | T101, T102 | new test file (T101); CLAUDE.md + design doc (T102) | ✅ |
+
+---
+
+## Task overview
+
+```
+Wave 1 ─┬─ T88: embeddings table + projector handlers
+        ├─ T89: branches table + projector handlers
+        └─ T90: Phase 3.6 carry-overs trio (chat-id SQL pushdown + lifecycle wording + legacy-fn consolidation)
+
+Wave 2 ─┬─ T91: embedding generation service (Featherless or local)
+        ├─ T92: vector search service via sqlite-vec
+        └─ T93: cross-chat search service (FTS over all owners)
+
+Wave 3 ─┬─ T94: branch_from_event service (event-log fork, branch metadata)
+        └─ T95: delete-impact computation service (cascade preview)
+
+Wave 4 ─── T96: combined FTS + vector retrieval ranking in search_memories
+
+Wave 5 ─── T97: memory_write enqueues embedding job + backfill script for existing memories
+
+Wave 6 ─── T98: drawer Phase 4 bundle — branching UI + significance review + hide-from-view + surgical delete + remaining v1 edits
+
+Wave 7 ─┬─ T99: snapshot UX (manual trigger, retention display, restore-from-snapshot UI)
+        └─ T100: cross-chat search UX (top-bar input + search results page)
+
+Wave 8 ─┬─ T101: cross-feature integration tests (vector × branching × delete × snapshot × search)
+        └─ T102: Phase 4 documentation update
+```
+
+Critical path: 8 sequential merge points. Total tasks: 15. Parallelism: Waves 1, 2, 3, 7, 8 dispatch concurrently (3-way and 2-way). Waves 4, 5, 6 are single-task by hot-file constraint.
+
+---
+
+## Wave 1 — Schema foundation + Phase 3.6 carry-overs (parallel)
+
+### Task 88: Embeddings table + projector handlers
+
+**Files:**
+
+- Create: `chat/db/migrations/0012_embeddings.sql`
+- Create: `chat/state/embeddings.py`
+- Create: `tests/test_embeddings_state.py`
+- Modify: `pyproject.toml` (add `sqlite-vec` dependency — controlling agent should pre-install before dispatch; the worktree commits the dependency declaration)
+
+**Spec:**
+
+Adds the `embeddings` table that stores per-memory embedding vectors for vector retrieval. Uses `sqlite-vec` virtual-table syntax for cosine-similarity search. Schema:
+
+```sql
+-- Load sqlite-vec extension at connection time (handled in chat/db/connection.py).
+-- Embeddings are stored as blobs in a vec0 virtual table for fast similarity search.
+
+CREATE VIRTUAL TABLE embeddings USING vec0(
+    memory_id INTEGER PRIMARY KEY,
+    embedding FLOAT[384]   -- 384-dim default; adjust per chosen model
+);
+
+-- Sidecar table for non-vector metadata (model used, dim, indexed_at).
+CREATE TABLE embeddings_meta (
+    memory_id INTEGER PRIMARY KEY,
+    model TEXT NOT NULL,
+    dim INTEGER NOT NULL,
+    indexed_at TEXT NOT NULL DEFAULT (datetime('now')),
+    FOREIGN KEY (memory_id) REFERENCES memories(id)
+);
+```
+
+(If `sqlite-vss` is chosen instead, replace `vec0` with `vss0` and adapt the dim declaration. Both have similar Python loading semantics.)
+
+**`chat/state/embeddings.py`:**
+
+- `@on("embedding_indexed")` payload `{memory_id, model, dim, vector: list[float]}`. Inserts into both `embeddings` and `embeddings_meta`. Idempotent via `INSERT OR REPLACE` (re-indexing a memory replaces the prior vector).
+- `@on("embedding_deindexed")` payload `{memory_id}`. Deletes from both tables. Used when a memory is purged via reset/cascade.
+- Reader `get_embedding_meta(conn, memory_id) -> dict | None` returns the meta row.
+
+The `chat/db/connection.py` `open_db` helper needs to load the sqlite-vec extension on each connection. Add:
+
+```python
+import sqlite_vec
+# Inside open_db, after connection is opened:
+conn.enable_load_extension(True)
+sqlite_vec.load(conn)
+conn.enable_load_extension(False)
+```
+
+This is a small modification to `connection.py`. Include it in T88's diff.
+
+**Tests:** 3 minimum.
+
+1. `test_embedding_indexed_inserts_row`: append `bot_authored`, `chat_created`, `memory_written` (creates a memory), then `embedding_indexed` with `vector=[0.1] * 384`. Project. Assert `embeddings_meta` row exists for that memory_id with the right model.
+2. `test_embedding_deindexed_removes_row`: same setup; index then de-index; assert row is gone.
+3. `test_vector_similarity_search_returns_nearest`: index two memories with distinct vectors; query for nearest neighbor of one vector; assert correct memory_id returned. Uses `sqlite-vec`'s `MATCH '...'` syntax (verify against actual sqlite-vec docs; adapt if needed).
+
+If running tests requires sqlite-vec to be loaded, the test fixture may need to skip / xfail when the extension isn't installed. Use `pytest.importorskip("sqlite_vec")` at the top of the test file.
+
+**Commit:** `feat: embeddings table + projector handlers via sqlite-vec (T88)`.
+
+**Notes:**
+
+- Schema version after migration alone: 12. T89 adds 0013, taking final to 13. The schema_version assertion in `tests/test_world.py` updates to 13 in the wave-merge step.
+- The `connection.py` change is small but cross-cutting — affects every `open_db` call. Verify the existing 343 tests still pass after the change.
+
+---
+
+### Task 89: Branches table + projector handlers
+
+**Files:**
+
+- Create: `chat/db/migrations/0013_branches.sql`
+- Create: `chat/state/branches.py`
+- Create: `tests/test_branches_state.py`
+
+**Spec:**
+
+Adds the `branches` table that records named alternate event-log forks. A branch is metadata: a name, an `origin_event_id` (the event we forked from), and a `head_event_id` (the latest event in this branch). The event log itself is unchanged — the branch table just **labels** linear ranges of event ids.
+
+```sql
+CREATE TABLE branches (
+    id INTEGER PRIMARY KEY,
+    name TEXT NOT NULL UNIQUE,
+    origin_event_id INTEGER NOT NULL,
+    head_event_id INTEGER NOT NULL,
+    chat_id TEXT,
+    created_at TEXT NOT NULL DEFAULT (datetime('now')),
+    is_active INTEGER NOT NULL DEFAULT 0
+);
+
+-- Exactly one row may have is_active = 1 at any time.
+CREATE UNIQUE INDEX branches_active_idx ON branches(is_active) WHERE is_active = 1;
+```
+
+The "main" branch is implicit and bootstrapped by the migration: `INSERT INTO branches (name, origin_event_id, head_event_id, is_active) VALUES ('main', 0, 0, 1);`. Subsequent branches reference an `origin_event_id` (the event that the branch forked from).
+
+`chat/state/branches.py`:
+
+- `@on("branch_created")` payload `{name, origin_event_id, chat_id?, head_event_id}`. Inserts a new row with `is_active=0`. Idempotent re-insertion via `INSERT OR IGNORE`.
+- `@on("branch_switched")` payload `{name}`. Sets `is_active=1` on the named branch and `is_active=0` on all others. Atomic via a single UPDATE.
+- `@on("branch_head_updated")` payload `{name, head_event_id}`. Updates `head_event_id` on the named branch. Used by the orchestrator when new events extend the branch.
+- Readers: `get_branch(conn, name)`, `list_branches(conn, chat_id=None)`, `active_branch(conn)`.
+
+**Tests:** 3 minimum.
+
+1. `test_branch_created_inserts_row`: append `branch_created` with name="experiment", origin_event_id=42; project; assert `get_branch(conn, "experiment")` returns the row.
+2. `test_branch_switched_atomic`: seed two branches; switch from one to the other; assert exactly one is active.
+3. `test_main_branch_bootstrapped_by_migration`: open a fresh DB, apply migrations; assert `active_branch(conn)["name"] == "main"`.
+
+**Commit:** `feat: branches table + projector handlers (T89)`.
+
+**Notes:**
+
+- Schema version after this migration alone: 13. Combined with T88: 13 (since T88 was 12, T89 stacks). Wave-merge bumps `tests/test_world.py` schema_version assertion to 13.
+- This task does NOT yet teach the orchestrator to consult `is_active` — the existing event_log queries assume a single timeline. T98 (drawer branching UI) will enable user-driven switches, but the actual "follow only the active branch" filter on event reads is a follow-up (Phase 4.5 nit; document in T102 docs sweep).
+
+---
+
+### Task 90: Phase 3.6 carry-overs trio
+
+**Files:**
+
+- Modify: `chat/services/turn_common.py` (push chat_id filter into SQL)
+- Modify: `chat/services/regenerate.py` (lifecycle warning wording tightening)
+- Modify: `chat/services/memory_write.py` (consolidate legacy `record_turn_memory` into the unified API or delete it)
+- Modify: `tests/test_turn_common.py`, `tests/test_regenerate.py`, `tests/test_memory_write.py`
+
+**Spec:** Three small Phase 3.6 carry-over fixes bundled because each is 1-line + 1-test.
+
+#### 90.1 — `read_recent_dialogue` chat-id SQL pushdown
+
+Per T80 review nit. Currently `read_recent_dialogue` filters chat_id post-fetch in Python. Push into SQL for tighter LIMIT semantics:
+
+```sql
+SELECT id, kind, payload_json
+FROM event_log
+WHERE kind IN ('user_turn', 'user_turn_edit', 'assistant_turn')
+  AND superseded_by IS NULL
+  AND hidden = 0
+  AND json_extract(payload_json, '$.chat_id') = ?
+ORDER BY id DESC
+LIMIT ?
+```
+
+Then the post-fetch loop becomes a simple reverse + slice — no chat_id check needed.
+
+**Test added:** `test_read_recent_dialogue_limit_respects_chat_scope` — seed two chats with 60 turns each; query chat_a with `limit=50`; assert returned rows are exactly 50 chat_a rows (not 50 cross-chat rows that filter down to <50 after Python).
+
+**Commit:** `perf: read_recent_dialogue pushes chat-id filter into SQL (T90.1)`.
+
+#### 90.2 — Lifecycle warning wording tightening
+
+Per T83.4 review nit. Current warning lists "lifecycle transitions from superseded turn are NOT being rolled back". When user regenerates an OLDER turn (T29 supports this), the warning lists intervening-turn transitions that legitimately stand. Tighten wording to "lifecycle transitions at-or-after turn X" so operators reading logs aren't misled.
+
+Change is one log message string. Test asserts the new wording appears.
+
+**Commit:** `chore: clarify regenerate lifecycle warning wording (T90.2)`.
+
+#### 90.3 — Legacy `record_turn_memory` consolidation
+
+Per T84 review nit. The original Phase 1 single-bot `record_turn_memory` function still exists alongside the unified `record_turn_memory_for_present`. Either:
+
+- (a) Remove the legacy function entirely; update any remaining callers to use the unified API.
+- (b) Convert it to a thin wrapper for backward compat.
+
+Pick (a) if there are zero remaining callers; (b) if any callers exist. Read the codebase to confirm. The mock-data seed scripts may still use the legacy fn.
+
+**Commit:** `refactor: consolidate legacy record_turn_memory into unified API (T90.3)`.
+
+**TDD process for T90:**
+
+1. Read all 3 affected files + their tests.
+2. Implement 90.1 with test; commit.
+3. Implement 90.2 with test; commit.
+4. Implement 90.3 with test; commit.
+5. Run full suite — should be 343 + 3 = 346 (or +2 if 90.3 had no behavioral change).
+
+---
+
+## Wave 2 — Embedding & search services (parallel)
+
+Three new service modules. Fully file-disjoint.
+
+### Task 91: Embedding generation service
+
+**Files:**
+
+- Create: `chat/services/embeddings.py`
+- Create: `tests/test_embeddings.py`
+
+**Spec:** Wraps the embedding API call. Signature:
+
+```python
+class EmbeddingResult(BaseModel):
+    vector: list[float]
+    model: str
+    dim: int
+
+async def generate_embedding(
+    client: LLMClient,    # or a separate embedding-specific client
+    *,
+    text: str,
+    model: str,
+    timeout_s: float = 30.0,
+) -> EmbeddingResult:
+    """Generate an embedding vector for the given text. Falls back to a
+    zero-vector with model='fallback' on failure (so callers get a deterministic
+    sentinel they can detect and skip indexing)."""
+```
+
+**Implementation:** call the embedding endpoint (Featherless OpenAI-compatible `/v1/embeddings`, or a local `sentence-transformers` model). Add a new method `client.embed(text, model)` to `LLMClient` Protocol (and to `MockLLMClient` and `FeatherlessClient`).
+
+**Embedding model choice:**
+
+Default to a small CPU-friendly model accessible through the existing Featherless setup:
+
+- If Featherless has `BAAI/bge-small-en-v1.5` or similar 384-dim model: use that.
+- If not: fall back to local `sentence-transformers/all-MiniLM-L6-v2` (384-dim, runs CPU). Add `sentence-transformers` to `pyproject.toml`.
+- Document choice in CLAUDE.md (T102 docs sweep).
+
+The 384 dim is hardcoded in T88's migration. If a different model with different dim is chosen, update T88's schema accordingly BEFORE T88 dispatches.
+
+**Tests:** 3 minimum.
+
+1. `test_generate_embedding_returns_vector_of_correct_dim`: mock embedding response with a 384-element vector; assert returned `vector` length is 384.
+2. `test_generate_embedding_returns_correct_model_metadata`: assert `result.model` matches the input.
+3. `test_generate_embedding_falls_back_on_failure`: mock the client to raise; assert the result is a 384-element zero vector with `model="fallback"`.
+
+**Commit:** `feat: embedding generation service (T91)`.
+
+---
+
+### Task 92: Vector search service via sqlite-vec
+
+**Files:**
+
+- Create: `chat/services/vector_search.py`
+- Create: `tests/test_vector_search.py`
+
+**Spec:** Wraps sqlite-vec's `MATCH` syntax for cosine-similarity search over the `embeddings` virtual table. Witness-filter aware (joins through `memories` table for the witness check).
+
+```python
+def vector_search(
+    conn,
+    *,
+    owner_id: str,
+    witness_role: str,    # "you" | "host" | "guest"
+    query_vector: list[float],
+    k: int = 4,
+) -> list[dict]:
+    """Return top-K memories by cosine similarity to query_vector,
+    witness-filtered for the requesting bot's POV. Returns same row
+    shape as state.memory.search_memories for combined-ranking
+    compatibility."""
+```
+
+SQL pattern (sqlite-vec):
+
+```sql
+SELECT m.id, m.text, m.pov_summary, m.significance, e.distance
+FROM embeddings e
+JOIN memories m ON m.id = e.memory_id
+WHERE e.embedding MATCH ?
+  AND k = ?
+  AND m.owner_id = ?
+  AND m.witness_<role> = 1
+ORDER BY e.distance ASC
+LIMIT ?
+```
+
+(Adapt to actual sqlite-vec syntax — use `vec0` MATCH semantics. The `witness_<role>` interpolation needs the same allowlist guard pattern as Phase 2.5 T72.3.)
+
+**Tests:** 3 minimum.
+
+1. `test_vector_search_returns_nearest_neighbors`: index 5 memories with synthetic vectors; query for nearest 3; assert correct order.
+2. `test_vector_search_respects_witness_filter`: index a memory with witness `[1, 1, 0]`; query with `witness_role="guest"`; assert empty result.
+3. `test_vector_search_respects_owner_filter`: index memories for two owners; assert query for owner_a doesn't return owner_b's memories.
+
+**Commit:** `feat: vector search service via sqlite-vec (T92)`.
+
+---
+
+### Task 93: Cross-chat search service
+
+**Files:**
+
+- Create: `chat/services/cross_chat_search.py`
+- Create: `tests/test_cross_chat_search.py`
+
+**Spec:** FTS5-based search across ALL chats and all owners (admin-style search; no witness filter). For "where did I last see this person mention X?" queries.
+
+```python
+def search_all_memories(
+    conn,
+    *,
+    query: str,
+    k: int = 20,
+) -> list[dict]:
+    """Search FTS across all owners and chats. Returns rows with
+    {memory_id, owner_id, chat_id, text, pov_summary, scene_id,
+    significance, ts}. Sorted by FTS rank."""
+```
+
+This is intentionally NOT witness-filtered — it's a power-user search surface. The UI (T100) prompts the user to acknowledge they're seeing memories across POVs.
+
+**Tests:** 3 minimum.
+
+1. `test_search_all_memories_returns_matches_across_owners`: seed 2 owners with overlapping keyword; search; assert both owner's matches appear.
+2. `test_search_all_memories_orders_by_fts_rank`: seed memories with varying FTS-match strength; assert order.
+3. `test_search_all_memories_respects_k_limit`.
+
+**Commit:** `feat: cross-chat search service (FTS5 over all owners) (T93)`.
+
+---
+
+## Wave 3 — Branching + delete services (parallel)
+
+Two new service modules. Fully file-disjoint.
+
+### Task 94: branch_from_event service
+
+**Files:**
+
+- Create: `chat/services/branching.py`
+- Create: `tests/test_branching.py`
+
+**Spec:**
+
+```python
+def branch_from_event(
+    conn,
+    *,
+    name: str,
+    origin_event_id: int,
+    chat_id: str | None = None,
+) -> int:
+    """Create a new named branch forking from origin_event_id.
+    Emits a branch_created event. Returns the new branch's row id.
+    Raises ValueError if name already exists."""
+
+def switch_active_branch(conn, *, name: str) -> None:
+    """Make the named branch active. Emits branch_switched. Subsequent
+    event reads should consult is_active to filter."""
+
+def list_branches_with_metadata(conn, chat_id: str | None = None) -> list[dict]:
+    """List branches with: name, origin_event_id, head_event_id, is_active,
+    event_count (number of events between origin and head, inclusive),
+    created_at."""
+```
+
+Tests cover: basic create, duplicate-name raises, switch updates `is_active` exclusively, list returns metadata.
+
+**Commit:** `feat: branching service (T94)`.
+
+---
+
+### Task 95: Delete-impact computation service
+
+**Files:**
+
+- Create: `chat/services/delete_impact.py`
+- Create: `tests/test_delete_impact.py`
+
+**Spec:** Computes the cascade impact of deleting a single event_log row (or a turn group: user_turn + assistant_turn + interjection if any). Returns a structured `ImpactReport` for the UI to render.
+
+```python
+class DeletedItem(BaseModel):
+    kind: str           # "memory" | "edge_update" | "scene_close" | etc.
+    description: str    # human-readable
+    target_id: int | str | None
+
+class ImpactReport(BaseModel):
+    target_event_id: int
+    cascading: list[DeletedItem]
+    notes: list[str]    # warnings, e.g. "this turn opened scene_X which has 3 subsequent turns"
+
+def compute_delete_impact(conn, *, target_event_id: int) -> ImpactReport:
+    """Walk the event log forward from target_event_id and identify
+    everything that depends on this event: child memory_written events,
+    edge_update events with this turn as source, scene_closed events
+    triggered by this turn, etc. Also identify subsequent turns that
+    REFERENCE this event (regenerated_from chains, etc.).
+    
+    Does NOT mutate the database. Pure computation for preview."""
+```
+
+The actual delete (truncate + supersede) is the existing rewind path from Phase 1 T31. T95 just builds the preview.
+
+**Tests:** 4 minimum.
+
+1. `test_impact_for_simple_turn_lists_memory_and_edges`: seed a chat with a turn that wrote 1 memory + 2 edge_updates. Compute impact. Assert the 3 items appear in `cascading`.
+2. `test_impact_for_scene_opening_turn_warns_about_subsequent_turns`: seed a turn that opened a scene + 5 subsequent turns. Assert `notes` mentions the dependency.
+3. `test_impact_for_regenerated_turn_lists_supersede_chain`: seed a turn that's been regenerated (has `superseded_by`). Compute impact for the original. Assert the chain appears.
+4. `test_impact_does_not_mutate_database`: snapshot event_log before + after; assert byte-identical.
+
+**Commit:** `feat: delete-impact computation service (T95)`.
+
+---
+
+## Wave 4 — Combined retrieval ranking (single)
+
+### Task 96: Combined FTS + vector retrieval ranking
+
+**Files:**
+
+- Modify: `chat/state/memory.py` — extend `search_memories` to optionally include vector hits
+- Modify: `tests/test_memory_search.py` — add 4 tests
+
+**Spec:**
+
+`search_memories` currently does FTS5 + Python-side significance/recency re-rank. Phase 4 adds:
+
+- An optional `query_vector: list[float] | None = None` kwarg.
+- When `query_vector` is provided, run `vector_search` (T92) for top-K-vector candidates.
+- Merge with FTS top-K candidates via reciprocal-rank fusion (RRF) or a simpler sum-of-ranks scheme — implementer's choice. Document the merge formula.
+- Final result is top-K from the fused set, with the existing significance + recency boosts applied as a final pass.
+
+When `query_vector` is None: existing behavior unchanged. Phase 1/2/3 callers that don't pass `query_vector` see no change.
+
+**Implementation note:** the embedding for the query (the speaker's recent context) must be generated by the caller (Wave 5 T97 wires the prompt-assembly pipeline to call `generate_embedding` on the dialogue tail). T96 only handles the search side — assumes the vector is pre-computed.
+
+**Tests:** 4 added.
+
+1. `test_search_memories_without_query_vector_uses_fts_only`: regression — call without `query_vector`; assert the existing FTS+rerank behavior.
+2. `test_search_memories_with_query_vector_includes_vector_hits`: index 5 memories where 1 is FTS-only-matching, 1 is vector-only-matching, 3 are unrelated. Pass both `query=...` and `query_vector=...`. Assert both the FTS hit and the vector hit appear in results.
+3. `test_search_memories_fusion_significance_bias_still_applies`: confirm the existing significance bias rerank still works on top of fused results.
+4. `test_search_memories_fusion_handles_empty_vector_results`: pass a vector for a memory that has no embeddings indexed; assert FTS-only results still come back.
+
+**Commit:** `feat: combined FTS + vector retrieval ranking (T96)`.
+
+---
+
+## Wave 5 — Memory write hook + backfill (single)
+
+### Task 97: Embedding generation hook + backfill script
+
+**Files:**
+
+- Modify: `chat/services/memory_write.py` — after each `memory_written` event, enqueue a background embedding job
+- Create: `chat/services/embedding_worker.py` — async worker that consumes the queue and emits `embedding_indexed` events
+- Create: `scripts/backfill_embeddings.py` — one-time script that walks all existing memories and embeds them
+- Modify: `chat/app.py` — wire the embedding worker into the lifespan startup
+- Modify: `tests/test_memory_write.py` — add 2 tests for the enqueue hook
+- Create: `tests/test_embedding_worker.py` — 3 tests for the worker drain logic
+
+**Spec:**
+
+After each successful `memory_written` event, enqueue an embedding job. The worker dequeues and:
+
+1. Reads the memory text (via `get_memory(conn, memory_id)`).
+2. Calls `generate_embedding(client, text=memory.text, model=settings.embedding_model)`.
+3. Appends `embedding_indexed` event with the result. (Skip if `result.model == "fallback"` — leave the memory un-indexed; will retry later via backfill.)
+
+The worker pattern mirrors Phase 1's `chat/services/significance.py` SignificanceWorker. Reuse its queue + lifecycle pattern.
+
+**Backfill script:**
+
+```bash
+.venv/bin/python scripts/backfill_embeddings.py [--limit N] [--dry-run]
+```
+
+Walks all memories where no `embeddings_meta` row exists. For each, generates an embedding and emits `embedding_indexed`. Useful for the initial migration after Phase 4 lands AND for periodic re-runs if an embedding model changes.
+
+**Tests:**
+
+`tests/test_memory_write.py`:
+1. `test_record_turn_memory_enqueues_embedding_job`: monkeypatch the worker's enqueue method; record_turn_memory_for_present; assert the worker received a job per memory.
+
+`tests/test_embedding_worker.py`:
+1. `test_worker_drains_jobs_and_emits_indexed_events`: enqueue 3 jobs with mock embeddings; run worker; assert 3 `embedding_indexed` events landed.
+2. `test_worker_skips_fallback_results`: mock the embedding service to return a fallback result; assert NO `embedding_indexed` event landed for that job.
+3. `test_worker_handles_concurrent_jobs_serially`: pin the Featherless 2-conn cap behavior (worker calls embed sequentially under the existing semaphore).
+
+**Commit (split):**
+
+- `feat: embedding worker drains queue and emits embedding_indexed events (T97.1)`
+- `feat: memory_write enqueues embedding job after each memory_written (T97.2)`
+- `feat: backfill_embeddings script for existing memories (T97.3)`
+
+**Verification gates:**
+
+- All Phase 1/2/3/3.5 memory tests still pass (regression critical).
+- New tests pass.
+- Manual smoke: run `scripts/backfill_embeddings.py --dry-run` against a seeded DB and verify expected count.
+
+---
+
+## Wave 6 — Drawer Phase 4 bundle (single task)
+
+### Task 98: Drawer Phase 4 features
+
+**Files:**
+
+- Modify: `chat/web/drawer.py` (add many new POST routes and GET extensions)
+- Modify: `chat/templates/_drawer.html` (add 5 new sections)
+- Create: `tests/test_drawer_phase4.py`
+
+**Spec:** Drawer affordances for 5 Phase 4 features. Single task by hot-file constraint; split into 5 commits internally.
+
+#### 98.1 — Branching UI
+
+GET drawer extension: `list_branches_with_metadata(conn)` → render in a "Branches" section (active branch highlighted + count of events).
+
+POST routes:
+- `/drawer/branch/create` — form `{name, origin_event_id}` → `branch_from_event` service.
+- `/drawer/branch/switch` — form `{name}` → `switch_active_branch`.
+- `/drawer/branch/from-turn/{event_id}` — convenience: branch from a specific turn (used by per-turn UI affordance).
+
+#### 98.2 — Significance review panel
+
+GET extension: significance distribution per chat (`SELECT significance, COUNT(*) GROUP BY significance`) → render histogram.
+
+POST route:
+- `/drawer/memory/significance/{memory_id}` — form `{new_value}` (already supported via T22 `manual_edit` `target_kind=memory_significance`); just add the UI form.
+
+Bulk re-rate is a Phase 4.5 polish — not in scope here. Just per-memory edit + distribution display.
+
+#### 98.3 — Hide-from-view toggle
+
+POST route:
+- `/drawer/turn/hide/{event_id}` — form `{hidden: bool}` → emits a `manual_edit` with `target_kind="turn_hidden"`.
+
+NEW `manual_edit` projector branch for `turn_hidden`: sets `event_log.hidden = ?` for the target event. Reuses the existing `hidden` column.
+
+UI affordance: per-turn checkbox in the chat surface or drawer (per-turn list with hide toggle).
+
+#### 98.4 — Surgical delete with cascade preview
+
+GET extension:
+- `/drawer/turn/delete-preview/{event_id}` → returns the `ImpactReport` (T95) rendered as a modal.
+
+POST route:
+- `/drawer/turn/delete/{event_id}` — invokes the rewind-and-truncate path (Phase 1 T31's `rewind_to_turn`) restricted to the target turn group.
+
+Important: this reuses the existing pre-rewind snapshot path so the action is undoable.
+
+#### 98.5 — Remaining v1 edits
+
+Audit: are any v1 fields STILL not editable from the drawer? Phase 2.5 T72.1 added edge_trust/edge_summary/memory_pov_summary/edge_knowledge_facts. T72.3 added witness flags. Anything left?
+
+Likely candidates: scene `narrative_anchor`, scene `weather`, container `properties` JSON. Add edit forms for any that surface during the audit. If none, this sub-fix is a no-op.
+
+**Tests:** 8+ in `tests/test_drawer_phase4.py` (one per sub-feature × happy path; plus 1 for the cascade-preview rendering).
+
+**Commits (5):**
+
+- `feat: drawer branching UI (T98.1)`
+- `feat: drawer significance review panel (T98.2)`
+- `feat: drawer hide-from-view toggle + manual_edit turn_hidden branch (T98.3)`
+- `feat: drawer surgical delete with cascade preview (T98.4)`
+- `feat: drawer remaining v1 field edits (T98.5)` (or "no-op audit" if nothing left)
+
+---
+
+## Wave 7 — Snapshot + cross-chat search UX (parallel)
+
+### Task 99: Snapshot UX
+
+**Files:**
+
+- Create: `chat/web/snapshots.py` (new route module)
+- Create: `chat/templates/snapshots.html` (snapshot list page)
+- Modify: `chat/templates/layout.html` (add "Snapshots" nav link)
+- Create: `tests/test_snapshot_ux.py`
+
+**Spec:** Surface the existing snapshot infrastructure (Phase 1 T20 wrote snapshots; Phase 4 makes them visible).
+
+GET `/snapshots` — list all snapshots (periodic + pre-rewind) with metadata: kind, created_at, event_log_size, file_size_bytes.
+
+POST `/snapshots/take` — manually trigger a snapshot now.
+
+POST `/snapshots/restore/{snapshot_id}` — restore from snapshot (with hard confirmation).
+
+GET `/snapshots/{snapshot_id}/preview` — show what's in the snapshot vs. current state.
+
+**Tests:** 4 minimum (list, take, restore, preview).
+
+**Commit:** `feat: snapshot UX (manual trigger, list, restore) (T99)`.
+
+---
+
+### Task 100: Cross-chat search UX
+
+**Files:**
+
+- Create: `chat/web/search.py` (new route module)
+- Create: `chat/templates/search.html` (search results page)
+- Modify: `chat/templates/layout.html` (add top-bar search input)
+- Create: `tests/test_search_ux.py`
+
+**Spec:** Top-bar search box submits to `/search?q=...`. Results page shows up to 50 matches across all chats and all owners (uses T93's `search_all_memories`). Each result shows: chat name, owner bot name, scene context, memory text excerpt with FTS highlight, "Open chat at this turn" link.
+
+**Tests:** 3 minimum.
+1. Search returns results from multiple chats.
+2. Empty query returns empty result set.
+3. Result links navigate to the right chat anchor.
+
+**Commit:** `feat: cross-chat search UX (top-bar input + results page) (T100)`.
+
+---
+
+## Wave 8 — Polish (parallel)
+
+### Task 101: Cross-feature integration tests
+
+**Files:**
+
+- Create: `tests/test_phase4_integration.py`
+
+**Spec:** End-to-end multi-feature flows. 5 tests minimum.
+
+1. **Vector retrieval feedback loop**: write a memory → embedding worker indexes it → search retrieves it via vector path.
+2. **Branch + diverge**: create branch B from turn 10 → switch to B → play 3 new turns → switch back to main → assert main's turn 11+ are still intact.
+3. **Surgical delete**: compute impact for a turn → confirm → assert event log truncated correctly + pre-rewind snapshot saved.
+4. **Hide + retrieval**: hide a turn → assert it doesn't appear in `read_recent_dialogue` (existing `hidden = 0` filter) → unhide → assert it reappears.
+5. **Cross-chat search**: write memories in 3 chats → search for keyword present in all 3 → assert all 3 appear in results.
+
+**Commit:** `test: phase 4 cross-feature integration coverage (T101)`.
+
+---
+
+### Task 102: Phase 4 documentation update
+
+**Files:**
+
+- Modify: `CLAUDE.md` (add "Phase 4 status" section; update behavioral defaults; add "Phase 4.5 / 5 backlog" with carry-overs)
+- Modify: `docs/plans/2026-04-26-v1-requirements-design.md` (annotate §13 Phase 4 as **Status: shipped 2026-04-27**)
+
+**Spec:**
+
+Mirror the Phase 3 / 3.5 status sections. Document:
+
+- **Vector retrieval**: sqlite-vec virtual table, embedding worker async pipeline, combined FTS + vector ranking via RRF.
+- **Branching**: forks the event log; UI in drawer; `is_active` flag plus orchestrator filter (caveat — see backlog if filter not yet wired into all readers).
+- **Drawer-edit on every field**: branching, significance review, hide-from-view, surgical delete with preview, plus any audit findings.
+- **Backup tooling**: snapshots panel surfaces existing infra.
+- **Significance review UI**: distribution + per-memory edit.
+- **Surgical delete + cascade preview**: piggybacks on rewind path; impact report from T95.
+- **Hide-from-view soft delete**: `manual_edit` `turn_hidden` branch.
+- **Cross-chat search**: top-bar + results page over T93's service.
+
+**Phase 4.5 / 5 backlog candidates** (reflect any discovered during execution):
+
+- Branching read-side filter — if T89's `is_active` isn't yet consulted by every event reader, this is the work to do.
+- Bulk significance re-rate (per T98.2 deferral).
+- Snapshot retention policy UI controls (per Phase 1 T19 deferred).
+- Auto-pin override UI (per Phase 2 design).
+- Embedding model swap migration tooling (when changing embedding model, need to re-embed everything).
+- Vector index optimization (HNSW vs flat — Phase 5 if needed).
+- Carry-overs that remained deferred from Phase 3.6: scene-close-on-cancel UX revisit, canned-queue brittleness fixture builder, full lifecycle rollback in regenerate.
+
+**Commit:** `docs: phase 4 status, behavioral defaults, deferred items (T102)`.
+
+---
+
+## Wrap-up
+
+After Wave 8 lands:
+
+1. **Run full suite** on `phase-4`: should be ~390+ tests passing (343 from Phase 3.5 + ~50 new).
+2. **Manual smoke** (recommended before opening the PR):
+   - Run `scripts/backfill_embeddings.py` against a seeded DB to verify vector indexing works.
+   - Search for a phrase that's substring-distinct but semantically similar to a memory; verify vector path returns it (FTS would miss).
+   - Create a branch from an old turn; switch; play a few turns; switch back.
+   - Trigger surgical delete on a turn; verify the impact preview matches what actually gets removed.
+   - Hide a turn; verify it disappears from the chat surface; unhide.
+   - Use top-bar search to find a phrase; verify cross-chat results appear.
+   - Click the "Snapshots" nav link; trigger a manual snapshot; verify it appears.
+3. **Push `phase-4`** to gitea.
+4. **Open PR** `phase-4 → main`.
+
+---
+
+## Notes for the controller running this plan
+
+- **External dependency**: `sqlite-vec` (or `sqlite-vss`) MUST be added to `pyproject.toml` and installed BEFORE Wave 1 dispatches. The migration in T88 expects the extension to be loadable.
+- **Embedding model choice**: pin in T91 spec before dispatch. The 384 dim is hardcoded in T88's migration; if a different dim is used, update T88 first.
+- **After each parallel wave**, run a code-review subagent. Combined spec+quality acceptable for trivial tasks (T90 carry-overs); separate spec + quality reviewers for vector-retrieval and integration tasks (T91, T96, T97, T98, T101) — surface area is larger.
+- **Don't dispatch Wave 5 until Wave 4 merged green.** T97 (memory_write enqueue) calls into the embedding-aware worker; the worker uses T91's `generate_embedding`. Both must be merged into `phase-4` first.
+- **Don't dispatch Wave 6 until Wave 5 merged green.** T98 (drawer) wires UI affordances over services from earlier waves.
+- **Token-spend rough estimate**: Phase 4 should be ~70-80% the size of Phase 3 (similar scope, larger per-task because vector + branching are non-trivial). Per-task spend similar to Phase 3's larger tasks (T59, T64).
+- **DO NOT break existing v1/v2/v3/v3.5 surface contracts.** Every test file that was green at the start of Phase 4 must stay green at the end. The cross-feature integration tests from Phase 3 (`tests/test_phase3_integration.py`) are particularly load-bearing.

docs/plans/2026-04-27-v4-phase4-implementation.md.tasks.json

@@ -0,0 +1,22 @@
+{
+  "planPath": "docs/plans/2026-04-27-v4-phase4-implementation.md",
+  "tasks": [
+    {"id": 88, "subject": "T88: embeddings table + projector handlers (sqlite-vec)", "status": "pending", "wave": 1, "parallelGroup": "wave-1"},
+    {"id": 89, "subject": "T89: branches table + projector handlers", "status": "pending", "wave": 1, "parallelGroup": "wave-1"},
+    {"id": 90, "subject": "T90: phase 3.6 carry-overs (chat-id pushdown + lifecycle wording + legacy fn consolidation)", "status": "pending", "wave": 1, "parallelGroup": "wave-1"},
+    {"id": 91, "subject": "T91: embedding generation service", "status": "pending", "wave": 2, "parallelGroup": "wave-2", "blockedBy": [88]},
+    {"id": 92, "subject": "T92: vector search service via sqlite-vec", "status": "pending", "wave": 2, "parallelGroup": "wave-2", "blockedBy": [88]},
+    {"id": 93, "subject": "T93: cross-chat search service (FTS5 over all owners)", "status": "pending", "wave": 2, "parallelGroup": "wave-2"},
+    {"id": 94, "subject": "T94: branch_from_event service", "status": "pending", "wave": 3, "parallelGroup": "wave-3", "blockedBy": [89]},
+    {"id": 95, "subject": "T95: delete-impact computation service", "status": "pending", "wave": 3, "parallelGroup": "wave-3"},
+    {"id": 96, "subject": "T96: combined FTS + vector retrieval ranking in search_memories", "status": "pending", "wave": 4, "parallelGroup": null, "blockedBy": [91, 92]},
+    {"id": 97, "subject": "T97: memory_write enqueues embedding job + backfill script", "status": "pending", "wave": 5, "parallelGroup": null, "blockedBy": [91, 96]},
+    {"id": 98, "subject": "T98: drawer Phase 4 bundle (branching + sig review + hide + surgical delete + remaining edits)", "status": "pending", "wave": 6, "parallelGroup": null, "blockedBy": [94, 95, 97]},
+    {"id": 99, "subject": "T99: snapshot UX (manual trigger + list + restore + preview)", "status": "pending", "wave": 7, "parallelGroup": "wave-7"},
+    {"id": 100, "subject": "T100: cross-chat search UX (top-bar + results page)", "status": "pending", "wave": 7, "parallelGroup": "wave-7", "blockedBy": [93]},
+    {"id": 101, "subject": "T101: cross-feature integration tests (vector × branching × delete × snapshot × search)", "status": "pending", "wave": 8, "parallelGroup": "wave-8", "blockedBy": [98, 99, 100]},
+    {"id": 102, "subject": "T102: Phase 4 documentation update", "status": "pending", "wave": 8, "parallelGroup": "wave-8", "blockedBy": [98, 99, 100]}
+  ],
+  "lastUpdated": "2026-04-27T00:00:00Z",
+  "notes": "15 tasks across 8 waves. Adds vector retrieval (sqlite-vec), branching UI, drawer-edit on every field, backup tooling, significance review UI, surgical delete with cascade preview, hide-from-view, and cross-chat search. Phase 3.6 carry-overs (3 small fixes) bundled into T90. External dependency: sqlite-vec must be installed BEFORE Wave 1 dispatch. Embedding model choice (default: 384-dim small model) pinned in T91 spec before dispatch — schema 0012 hardcodes 384 dim. Two new schema migrations (0012 embeddings, 0013 branches), final schema version 13. Uses task ids T88-T102."
+}

scripts/backfill_embeddings.py

@@ -0,0 +1,97 @@
+"""Backfill embeddings for memories that lack them (T97, Phase 4).
+
+Walks all memories where no row exists in the ``embeddings`` table. For
+each, calls :func:`chat.services.embeddings.generate_embedding` and emits
+an ``embedding_indexed`` event so the projector lands the vector.
+
+Phase 4 ships the deterministic local pseudo-embedding so this script
+runs synchronously without a network round-trip — the LLMClient argument
+is not needed on the pseudo path. Phase 4.5+ will need a real client.
+
+Run from the repo root:
+    .venv/bin/python scripts/backfill_embeddings.py [--limit N] [--dry-run]
+"""
+
+from __future__ import annotations
+
+import argparse
+import asyncio
+
+from chat.config import load_settings
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_and_apply
+from chat.services.embeddings import (
+    FALLBACK_EMBEDDING_MODEL,
+    generate_embedding,
+)
+
+# Trigger projector handler registration so ``append_and_apply`` lands
+# the embedding rows correctly.
+import chat.state.embeddings  # noqa: F401
+import chat.state.entities  # noqa: F401
+import chat.state.memory  # noqa: F401
+import chat.state.world  # noqa: F401
+
+
+async def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--limit",
+        type=int,
+        default=None,
+        help="Cap the number of memories backfilled in this run.",
+    )
+    parser.add_argument(
+        "--dry-run",
+        action="store_true",
+        help="Print the count of memories needing embeddings, then exit.",
+    )
+    args = parser.parse_args()
+
+    settings = load_settings()
+    settings.db_path.parent.mkdir(parents=True, exist_ok=True)
+    apply_migrations(settings.db_path)
+
+    with open_db(settings.db_path) as conn:
+        sql = (
+            "SELECT m.id, m.pov_summary FROM memories m "
+            "LEFT JOIN embeddings e ON e.memory_id = m.id "
+            "WHERE e.memory_id IS NULL "
+            "ORDER BY m.id"
+        )
+        if args.limit is not None:
+            sql += f" LIMIT {int(args.limit)}"
+        rows = conn.execute(sql).fetchall()
+        print(f"Found {len(rows)} memories needing embeddings.")
+        if args.dry_run:
+            return
+
+        indexed = 0
+        skipped = 0
+        for memory_id, text in rows:
+            result = await generate_embedding(
+                client=None,  # pseudo path: no client needed
+                text=text or "",
+            )
+            if result.model == FALLBACK_EMBEDDING_MODEL:
+                print(f"  Skipping memory_id={memory_id} (empty text)")
+                skipped += 1
+                continue
+            append_and_apply(
+                conn,
+                kind="embedding_indexed",
+                payload={
+                    "memory_id": memory_id,
+                    "model": result.model,
+                    "dim": result.dim,
+                    "vector": result.vector,
+                },
+            )
+            indexed += 1
+            print(f"  Indexed memory_id={memory_id}")
+        print(f"Done. Indexed {indexed}, skipped {skipped}.")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())

tests/test_branches_state.py

@@ -0,0 +1,141 @@
+from __future__ import annotations
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+import chat.state.branches  # registers handlers
+from chat.state.branches import active_branch, get_branch, list_branches
+
+
+def test_main_branch_bootstrapped_by_migration(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        active = active_branch(conn)
+        assert active is not None
+        assert active["name"] == "main"
+        assert active["is_active"] is True
+        assert active["origin_event_id"] == 0
+        assert active["head_event_id"] == 0
+
+
+def test_branch_created_inserts_row(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(
+            conn,
+            kind="branch_created",
+            payload={
+                "name": "experiment",
+                "origin_event_id": 42,
+                "chat_id": "chat_a",
+            },
+        )
+        project(conn)
+
+        b = get_branch(conn, "experiment")
+        assert b is not None
+        assert b["name"] == "experiment"
+        assert b["origin_event_id"] == 42
+        # head defaults to origin when not specified
+        assert b["head_event_id"] == 42
+        assert b["chat_id"] == "chat_a"
+        assert b["is_active"] is False
+
+        # main remains active
+        active = active_branch(conn)
+        assert active is not None
+        assert active["name"] == "main"
+
+
+def test_branch_switched_atomic(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(
+            conn,
+            kind="branch_created",
+            payload={
+                "name": "experiment",
+                "origin_event_id": 5,
+                "chat_id": "chat_a",
+            },
+        )
+        append_event(
+            conn,
+            kind="branch_switched",
+            payload={"name": "experiment"},
+        )
+        project(conn)
+
+        active = active_branch(conn)
+        assert active is not None
+        assert active["name"] == "experiment"
+
+        main = get_branch(conn, "main")
+        assert main is not None
+        assert main["is_active"] is False
+
+        # switch back
+        append_event(
+            conn,
+            kind="branch_switched",
+            payload={"name": "main"},
+        )
+        project(conn)
+
+        active2 = active_branch(conn)
+        assert active2 is not None
+        assert active2["name"] == "main"
+
+        experiment = get_branch(conn, "experiment")
+        assert experiment is not None
+        assert experiment["is_active"] is False
+
+
+def test_branch_head_updated_changes_head(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(
+            conn,
+            kind="branch_created",
+            payload={
+                "name": "experiment",
+                "origin_event_id": 10,
+                "head_event_id": 10,
+                "chat_id": "chat_a",
+            },
+        )
+        append_event(
+            conn,
+            kind="branch_head_updated",
+            payload={"name": "experiment", "head_event_id": 20},
+        )
+        project(conn)
+
+        b = get_branch(conn, "experiment")
+        assert b is not None
+        assert b["head_event_id"] == 20
+
+
+def test_list_branches_returns_all(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(
+            conn,
+            kind="branch_created",
+            payload={
+                "name": "experiment",
+                "origin_event_id": 1,
+                "chat_id": "chat_a",
+            },
+        )
+        project(conn)
+
+        names = [b["name"] for b in list_branches(conn)]
+        assert "main" in names
+        assert "experiment" in names

tests/test_branching.py

@@ -0,0 +1,131 @@
+"""Tests for the branching service (T94, Phase 4)."""
+
+from __future__ import annotations
+
+import pytest
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_and_apply
+import chat.state.branches  # noqa: F401  registers handlers
+from chat.services.branching import (
+    branch_from_event,
+    list_branches_with_metadata,
+    switch_active_branch,
+)
+from chat.state.branches import active_branch, get_branch
+
+
+def _seed_event(conn) -> int:
+    """Append a benign event so we have a real event_log row to fork from.
+
+    ``user_turn`` is a transcript-only kind with no registered projector
+    handler, so ``append_and_apply`` is a clean no-op on the projector
+    side regardless of what other handlers are imported by the suite.
+    """
+    return append_and_apply(
+        conn,
+        kind="user_turn",
+        payload={"chat_id": "c1", "text": "hi"},
+    )
+
+
+def test_branch_from_event_creates_branch_via_event(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        seed_id = _seed_event(conn)
+
+        new_id = branch_from_event(
+            conn,
+            name="experiment",
+            origin_event_id=seed_id,
+            chat_id="c1",
+        )
+        assert isinstance(new_id, int) and new_id > 0
+
+        b = get_branch(conn, "experiment")
+        assert b is not None
+        assert b["id"] == new_id
+        assert b["origin_event_id"] == seed_id
+        assert b["head_event_id"] == seed_id
+        assert b["chat_id"] == "c1"
+        assert b["is_active"] is False
+
+        # branch_created event landed in event_log
+        row = conn.execute(
+            "SELECT COUNT(*) FROM event_log WHERE kind = 'branch_created'"
+        ).fetchone()
+        assert row[0] == 1
+
+
+def test_branch_from_event_duplicate_name_raises(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        seed_id = _seed_event(conn)
+        branch_from_event(conn, name="dup", origin_event_id=seed_id)
+
+        with pytest.raises(ValueError, match="already exists"):
+            branch_from_event(conn, name="dup", origin_event_id=seed_id)
+
+
+def test_branch_from_event_invalid_origin_raises(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        with pytest.raises(ValueError, match="does not exist"):
+            branch_from_event(conn, name="ghost", origin_event_id=99999)
+
+
+def test_switch_active_branch_changes_active(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        seed_id = _seed_event(conn)
+        branch_from_event(conn, name="experiment", origin_event_id=seed_id)
+
+        switch_active_branch(conn, name="experiment")
+        active = active_branch(conn)
+        assert active is not None
+        assert active["name"] == "experiment"
+
+        # Switch back to main.
+        switch_active_branch(conn, name="main")
+        active2 = active_branch(conn)
+        assert active2 is not None
+        assert active2["name"] == "main"
+
+
+def test_switch_active_branch_unknown_name_raises(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        with pytest.raises(ValueError, match="does not exist"):
+            switch_active_branch(conn, name="nope")
+
+
+def test_list_branches_with_metadata_includes_event_count(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        # Seed enough events to cover origin=10 and head=15.
+        for _ in range(15):
+            _seed_event(conn)
+
+        # Create the branch at origin=10, then bump its head to 15.
+        branch_from_event(conn, name="exp", origin_event_id=10)
+        append_and_apply(
+            conn,
+            kind="branch_head_updated",
+            payload={"name": "exp", "head_event_id": 15},
+        )
+
+        rows = {b["name"]: b for b in list_branches_with_metadata(conn)}
+
+        # main: bootstrap state — origin=0, head=0 — event_count == 0.
+        assert rows["main"]["event_count"] == 0
+        # exp: origin=10, head=15 — event_count == 6 (inclusive).
+        assert rows["exp"]["origin_event_id"] == 10
+        assert rows["exp"]["head_event_id"] == 15
+        assert rows["exp"]["event_count"] == 6

tests/test_cross_chat_search.py

@@ -0,0 +1,155 @@
+"""T93 (Phase 4): cross-chat FTS5 search across all owners and chats.
+
+Verifies that ``chat.services.cross_chat_search.search_all_memories``:
+* surfaces matches across multiple owner_ids (the per-owner restriction
+  used by ``state.memory.search_memories`` is intentionally absent),
+* applies no witness filter (admin/power-user surface),
+* orders results by FTS5 BM25 rank (lower = stronger match, surfaced
+  first), and
+* honours the ``k`` LIMIT and the empty-query fast-path.
+"""
+
+from __future__ import annotations
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+from chat.services.cross_chat_search import search_all_memories
+import chat.state.memory  # noqa: F401  (registers memory_written handler)
+
+
+def _seed(db, *, memory_specs):
+    """Apply migrations + project a list of memory_written events."""
+    apply_migrations(db)
+    with open_db(db) as conn:
+        for spec in memory_specs:
+            payload = {
+                "owner_id": spec.get("owner_id", "bot_a"),
+                "chat_id": spec.get("chat_id", "chat_bot_a"),
+                "pov_summary": spec["pov_summary"],
+                "witness_you": spec.get("witness_you", 1),
+                "witness_host": spec.get("witness_host", 1),
+                "witness_guest": spec.get("witness_guest", 0),
+                "source": "direct",
+                "reliability": 1.0,
+                "significance": spec.get("significance", 1),
+                "pinned": 0,
+                "auto_pinned": 0,
+            }
+            append_event(conn, kind="memory_written", payload=payload)
+        project(conn)
+
+
+def test_search_all_memories_returns_matches_across_owners(tmp_path):
+    """Cross-owner: a single query must surface memories from every owner.
+
+    The per-owner ``owner_id = ?`` predicate that ``search_memories`` uses
+    is intentionally absent here, so a "rabbit" memory under ``bot_a`` and
+    one under ``bot_b`` should both come back from a single call.
+    """
+    db = tmp_path / "t.db"
+    _seed(
+        db,
+        memory_specs=[
+            {
+                "owner_id": "bot_a",
+                "chat_id": "chat_bot_a",
+                "pov_summary": "the rabbit darted into the brambles",
+            },
+            {
+                "owner_id": "bot_b",
+                "chat_id": "chat_bot_b",
+                "pov_summary": "a white rabbit watched from the hedge",
+            },
+            # Distractor: must not appear for "rabbit".
+            {
+                "owner_id": "bot_a",
+                "chat_id": "chat_bot_a",
+                "pov_summary": "the kettle whistled",
+            },
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_all_memories(conn, query="rabbit")
+        owners = {row["owner_id"] for row in out}
+        assert owners == {"bot_a", "bot_b"}
+        assert len(out) == 2
+        # Returned shape contract.
+        for row in out:
+            assert set(row.keys()) >= {
+                "memory_id",
+                "owner_id",
+                "chat_id",
+                "scene_id",
+                "pov_summary",
+                "significance",
+                "ts",
+                "fts_rank",
+            }
+
+
+def test_search_all_memories_orders_by_fts_rank(tmp_path):
+    """Stronger BM25 match must come first (rank ASC = lower is better)."""
+    db = tmp_path / "t.db"
+    _seed(
+        db,
+        memory_specs=[
+            # Single occurrence -> weaker BM25 score.
+            {
+                "owner_id": "bot_a",
+                "chat_id": "chat_bot_a",
+                "pov_summary": "a rabbit appeared",
+            },
+            # Triple occurrence in a short row -> stronger BM25 score.
+            {
+                "owner_id": "bot_b",
+                "chat_id": "chat_bot_b",
+                "pov_summary": "rabbit rabbit rabbit",
+            },
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_all_memories(conn, query="rabbit", k=5)
+        assert len(out) == 2
+        # Stronger match first; fts_rank monotonically non-decreasing
+        # (lower-is-better, so ASC).
+        assert out[0]["pov_summary"] == "rabbit rabbit rabbit"
+        assert out[0]["fts_rank"] <= out[1]["fts_rank"]
+
+
+def test_search_all_memories_respects_k_limit(tmp_path):
+    """LIMIT ? must cap result count even when more matches exist."""
+    db = tmp_path / "t.db"
+    _seed(
+        db,
+        memory_specs=[
+            {
+                "owner_id": f"bot_{i}",
+                "chat_id": f"chat_{i}",
+                "pov_summary": f"rabbit sighting number {i}",
+            }
+            for i in range(10)
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_all_memories(conn, query="rabbit", k=3)
+        assert len(out) == 3
+
+
+def test_search_all_memories_empty_query_returns_empty(tmp_path):
+    """Empty / whitespace-only query must short-circuit to []."""
+    db = tmp_path / "t.db"
+    _seed(
+        db,
+        memory_specs=[
+            {
+                "owner_id": "bot_a",
+                "chat_id": "chat_bot_a",
+                "pov_summary": "the rabbit darted into the brambles",
+            },
+        ],
+    )
+    with open_db(db) as conn:
+        assert search_all_memories(conn, query="") == []
+        assert search_all_memories(conn, query="   ") == []

tests/test_delete_impact.py

@@ -0,0 +1,248 @@
+"""Tests for Task 95 — delete-impact computation service (Phase 4).
+
+`compute_delete_impact` walks event_log forward from a target event_id and
+produces an :class:`ImpactReport` describing what would be removed if
+rewind-to-target were invoked. It is a pure preview — no database mutation.
+T98's drawer surgical-delete UI uses this to render an "are you sure?"
+modal before invoking the actual rewind path.
+"""
+
+from __future__ import annotations
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_event
+from chat.services.delete_impact import compute_delete_impact
+
+
+def _seed_chat(conn) -> tuple[int, int]:
+    """Append minimal bot + chat events; return their event ids."""
+    bot_id = append_event(
+        conn,
+        kind="bot_authored",
+        payload={
+            "id": "bot_a",
+            "name": "BotA",
+            "persona": "...",
+            "voice_samples": [],
+            "traits": [],
+            "backstory": "",
+            "initial_relationship_to_you": "",
+            "kickoff_prose": "",
+        },
+    )
+    chat_id = append_event(
+        conn,
+        kind="chat_created",
+        payload={
+            "id": "chat_bot_a",
+            "host_bot_id": "bot_a",
+            "initial_time": "2026-04-26T20:00:00+00:00",
+            "narrative_anchor": "Day 1",
+            "weather": "",
+        },
+    )
+    return bot_id, chat_id
+
+
+def test_impact_for_simple_turn_lists_memory_and_edges(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        _seed_chat(conn)
+        user_id = append_event(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "hey there friend",
+                "segments": [],
+            },
+        )
+        append_event(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "Hi! Good to see you.",
+                "truncated": False,
+                "user_turn_id": user_id,
+            },
+        )
+        append_event(
+            conn,
+            kind="memory_written",
+            payload={
+                "owner_id": "bot_a",
+                "chat_id": "chat_bot_a",
+                "pov_summary": "You greeted me warmly today.",
+                "witness_you": 1,
+                "witness_host": 1,
+                "witness_guest": 0,
+                "source": "turn",
+                "reliability": 1.0,
+                "significance": 1,
+                "pinned": 0,
+                "auto_pinned": 0,
+            },
+        )
+        append_event(
+            conn,
+            kind="edge_update",
+            payload={
+                "source_id": "you",
+                "target_id": "bot_a",
+                "affinity_delta": 0.1,
+            },
+        )
+
+        report = compute_delete_impact(conn, target_event_id=user_id)
+
+    assert report.target_event_id == user_id
+    kinds = [item.kind for item in report.cascading]
+    # Walk from user_turn forward — user_turn, assistant_turn,
+    # memory_written, edge_update should all be in scope, in order.
+    assert kinds == [
+        "user_turn",
+        "assistant_turn",
+        "memory_written",
+        "edge_update",
+    ]
+    # Memory description includes the pov_summary excerpt.
+    mem_item = report.cascading[2]
+    assert "memory:" in mem_item.description
+    assert "greeted" in mem_item.description
+    # Edge description includes both endpoints.
+    edge_item = report.cascading[3]
+    assert "you" in edge_item.description
+    assert "bot_a" in edge_item.description
+    assert edge_item.target_id == "you->bot_a"
+    # Notes mentions total count.
+    assert any("4 events" in n for n in report.notes)
+
+
+def test_impact_for_scene_opening_turn_warns_about_subsequent(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        _seed_chat(conn)
+        early_id = append_event(
+            conn,
+            kind="user_turn",
+            payload={"chat_id": "chat_bot_a", "prose": "the start", "segments": []},
+        )
+        append_event(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "ok",
+                "truncated": False,
+                "user_turn_id": early_id,
+            },
+        )
+        append_event(
+            conn,
+            kind="scene_closed",
+            payload={
+                "scene_id": 1,
+                "closed_at": "2026-04-26T21:00:00+00:00",
+                "significance": 2,
+            },
+        )
+
+        report = compute_delete_impact(conn, target_event_id=early_id)
+
+    # Scene-close warning fires when one is in scope.
+    assert any("scene close" in n.lower() for n in report.notes)
+    # The scene_closed event also appears as a cascading item.
+    assert any(item.kind == "scene_closed" for item in report.cascading)
+
+
+def test_impact_for_missing_event_returns_empty_with_note(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        _seed_chat(conn)
+        report = compute_delete_impact(conn, target_event_id=999_999)
+
+    assert report.cascading == []
+    assert any("not found" in n for n in report.notes)
+
+
+def test_impact_does_not_mutate_database(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        _seed_chat(conn)
+        user_id = append_event(
+            conn,
+            kind="user_turn",
+            payload={"chat_id": "chat_bot_a", "prose": "hi", "segments": []},
+        )
+        append_event(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "hello",
+                "truncated": False,
+                "user_turn_id": user_id,
+            },
+        )
+
+        # Snapshot all event_log rows as a tuple-of-tuples.
+        before = conn.execute(
+            "SELECT id, branch_id, ts, kind, payload_json, superseded_by, "
+            "hidden FROM event_log ORDER BY id"
+        ).fetchall()
+
+        compute_delete_impact(conn, target_event_id=user_id)
+
+        after = conn.execute(
+            "SELECT id, branch_id, ts, kind, payload_json, superseded_by, "
+            "hidden FROM event_log ORDER BY id"
+        ).fetchall()
+
+    # Byte-identical: nothing inserted, deleted, or updated.
+    assert before == after
+
+
+def test_impact_includes_regenerated_from_warning(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        _seed_chat(conn)
+        original_id = append_event(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "first try",
+                "truncated": False,
+                "user_turn_id": 0,
+            },
+        )
+        regen_id = append_event(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "second try",
+                "truncated": False,
+                "user_turn_id": 0,
+                "regenerated_from": original_id,
+            },
+        )
+
+        report = compute_delete_impact(conn, target_event_id=regen_id)
+
+    # The regenerated_from note carries the original event id so the user
+    # knows the original turn isn't lost.
+    assert any("regenerated from" in n for n in report.notes)
+    assert any(str(original_id) in n for n in report.notes)

tests/test_drawer_phase4.py

@@ -0,0 +1,523 @@
+"""T98 (Phase 4): drawer phase-4 bundle.
+
+Five sub-features extending the chat drawer:
+
+* T98.1 — branching UI (create / switch / from-turn).
+* T98.2 — significance-review panel (distribution + significance edits).
+* T98.3 — hide-from-view toggle (per-turn, via ``manual_edit`` projector
+  branch ``turn_hidden``).
+* T98.4 — surgical delete with cascade preview (preview modal +
+  rewind execution against a target turn).
+* T98.5 — remaining v1 edits (chat narrative_anchor + weather).
+
+Tests follow the T59 pattern in ``tests/test_drawer_events_threads_skip.py``
+— a TestClient against the real FastAPI app with a per-test temp DB.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+from fastapi.testclient import TestClient
+
+from chat.app import app
+from chat.db.connection import open_db
+from chat.eventlog.log import append_and_apply, append_event
+from chat.eventlog.projector import project
+
+
+@pytest.fixture
+def client(tmp_path, monkeypatch):
+    cfg = tmp_path / "config.toml"
+    cfg.write_text('featherless_api_key = "test"\n')
+    monkeypatch.setenv("CHAT_CONFIG_PATH", str(cfg))
+    db = tmp_path / "test.db"
+    monkeypatch.setenv("CHAT_DB_PATH", str(db))
+    with TestClient(app) as c:
+        if hasattr(app.state, "background_worker"):
+            app.state.background_worker.enabled = False
+        yield c
+
+
+def _bot_payload(bot_id: str, name: str) -> dict:
+    return {
+        "id": bot_id,
+        "name": name,
+        "persona": "...",
+        "voice_samples": [],
+        "traits": [],
+        "backstory": "",
+        "initial_relationship_to_you": "",
+        "kickoff_prose": "",
+    }
+
+
+def _seed_chat(db: Path, *, with_scene: bool = True) -> int:
+    """Seed a chat hosted by ``bot_a``; return the latest event id (chat_created)."""
+    with open_db(db) as conn:
+        append_event(conn, kind="bot_authored", payload=_bot_payload("bot_a", "BotA"))
+        append_event(
+            conn,
+            kind="you_authored",
+            payload={"name": "Me", "pronouns": "they/them", "persona": ""},
+        )
+        chat_event_id = append_event(
+            conn,
+            kind="chat_created",
+            payload={
+                "id": "chat_bot_a",
+                "host_bot_id": "bot_a",
+                "initial_time": "2026-04-26T20:00:00+00:00",
+                "narrative_anchor": "Day 1",
+                "weather": "",
+            },
+        )
+        if with_scene:
+            append_event(
+                conn,
+                kind="scene_opened",
+                payload={
+                    "chat_id": "chat_bot_a",
+                    "container_id": None,
+                    "started_at": "2026-04-26T20:00:00+00:00",
+                    "participants": ["you", "bot_a"],
+                },
+            )
+        project(conn)
+        return chat_event_id
+
+
+# ---------------------------------------------------------------------------
+# T98.1 — branching UI.
+# ---------------------------------------------------------------------------
+
+
+def test_t98_1_create_branch_emits_branch_created_and_renders(client, tmp_path):
+    db = tmp_path / "test.db"
+    seed_id = _seed_chat(db)
+
+    response = client.post(
+        "/chats/chat_bot_a/drawer/branch/create",
+        data={"name": "experiment_a", "origin_event_id": str(seed_id)},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        rows = conn.execute(
+            "SELECT COUNT(*) FROM event_log WHERE kind = 'branch_created'"
+        ).fetchone()
+        assert rows[0] == 1
+        from chat.state.branches import get_branch
+
+        b = get_branch(conn, "experiment_a")
+        assert b is not None
+        assert b["origin_event_id"] == seed_id
+        assert b["chat_id"] == "chat_bot_a"
+
+    # Drawer partial lists the new branch.
+    body = response.text
+    assert "<h3>Branches</h3>" in body
+    assert "experiment_a" in body
+
+
+def test_t98_1_switch_branch_marks_active_and_unknown_400s(client, tmp_path):
+    db = tmp_path / "test.db"
+    seed_id = _seed_chat(db)
+
+    # Create branch directly via the service so this test focuses on switch.
+    with open_db(db) as conn:
+        from chat.services.branching import branch_from_event
+
+        branch_from_event(
+            conn, name="experiment_b", origin_event_id=seed_id, chat_id="chat_bot_a"
+        )
+
+    response = client.post(
+        "/chats/chat_bot_a/drawer/branch/switch",
+        data={"name": "experiment_b"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        from chat.state.branches import active_branch
+
+        active = active_branch(conn)
+        assert active is not None
+        assert active["name"] == "experiment_b"
+
+    # Unknown branch -> 400.
+    bad = client.post(
+        "/chats/chat_bot_a/drawer/branch/switch",
+        data={"name": "ghost_branch"},
+    )
+    assert bad.status_code == 400
+
+
+def test_t98_1_branch_from_turn_emits_branch_created(client, tmp_path):
+    db = tmp_path / "test.db"
+    seed_id = _seed_chat(db)
+
+    # Append an extra turn so we can branch from it specifically.
+    with open_db(db) as conn:
+        turn_id = append_event(
+            conn,
+            kind="user_turn",
+            payload={"chat_id": "chat_bot_a", "prose": "hi", "segments": []},
+        )
+
+    response = client.post(
+        f"/chats/chat_bot_a/drawer/branch/from-turn/{turn_id}",
+        data={"name": "fork_at_turn"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        from chat.state.branches import get_branch
+
+        b = get_branch(conn, "fork_at_turn")
+        assert b is not None
+        assert b["origin_event_id"] == turn_id
+        assert b["chat_id"] == "chat_bot_a"
+
+    # Duplicate name -> 400 from service ValueError.
+    dup = client.post(
+        f"/chats/chat_bot_a/drawer/branch/from-turn/{turn_id}",
+        data={"name": "fork_at_turn"},
+    )
+    assert dup.status_code == 400
+    assert seed_id < turn_id  # sanity: turn is after chat_created
+
+
+# ---------------------------------------------------------------------------
+# T98.2 — significance review panel.
+# ---------------------------------------------------------------------------
+
+
+def _seed_memories_for_significance(db: Path) -> list[int]:
+    """Seed three memories with significance levels 0, 1, 2. Returns ids.
+
+    Uses ``append_and_apply`` (vs ``append_event`` + a final ``project``)
+    so each row is applied exactly once — the chat row was already
+    materialised by ``_seed_chat`` and a re-projection would conflict
+    on ``chats.id`` UNIQUE.
+    """
+    ids: list[int] = []
+    with open_db(db) as conn:
+        for sig in (0, 1, 2):
+            append_and_apply(
+                conn,
+                kind="memory_written",
+                payload={
+                    "owner_id": "bot_a",
+                    "chat_id": "chat_bot_a",
+                    "pov_summary": f"memory at significance {sig}",
+                    "witness_you": 1,
+                    "witness_host": 1,
+                    "witness_guest": 0,
+                    "significance": sig,
+                },
+            )
+        rows = conn.execute(
+            "SELECT id FROM memories WHERE chat_id = 'chat_bot_a' "
+            "ORDER BY id ASC"
+        ).fetchall()
+        ids = [int(r[0]) for r in rows]
+    return ids
+
+
+def test_t98_2_distribution_renders_per_significance_bucket(client, tmp_path):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+    _seed_memories_for_significance(db)
+
+    response = client.get("/chats/chat_bot_a/drawer")
+    assert response.status_code == 200
+    body = response.text
+
+    # Section heading + bar entries for each significance level.
+    assert "<h3>Significance review</h3>" in body
+    # All four buckets appear by their canonical label even when count=0.
+    assert ">★★ (3)<" in body or "(3)" in body
+    # The distribution markup names each level explicitly.
+    for level in (0, 1, 2, 3):
+        assert f"sig-bar sig-{level}" in body
+    # Three seeded memories (sigs 0, 1, 2) — each has a count = 1 bar.
+    # We don't pin exact text formatting, just verify the per-level bars
+    # are present.
+
+
+def test_t98_2_edit_significance_via_existing_route_lands_manual_edit(
+    client, tmp_path
+):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+    ids = _seed_memories_for_significance(db)
+
+    target_id = ids[0]  # initially significance=0
+    response = client.post(
+        f"/chats/chat_bot_a/drawer/memory/{target_id}/significance",
+        data={"significance": "3"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        # Significance updated in the projected table.
+        row = conn.execute(
+            "SELECT significance FROM memories WHERE id = ?", (target_id,)
+        ).fetchone()
+        assert int(row[0]) == 3
+
+        # manual_edit landed in the event log with the prior snapshot.
+        import json as _json
+
+        log_rows = conn.execute(
+            "SELECT payload_json FROM event_log "
+            "WHERE kind = 'manual_edit' ORDER BY id DESC LIMIT 1"
+        ).fetchone()
+        payload = _json.loads(log_rows[0])
+        assert payload["target_kind"] == "memory_significance"
+        assert int(payload["target_id"]) == target_id
+        assert payload["prior_value"] == 0
+        assert payload["new_value"] == 3
+
+
+# ---------------------------------------------------------------------------
+# T98.3 — hide-from-view toggle.
+# ---------------------------------------------------------------------------
+
+
+def _seed_turns(db: Path) -> tuple[int, int]:
+    """Append one user_turn + one assistant_turn; return their event ids."""
+    with open_db(db) as conn:
+        user_id = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "How are you doing today?",
+                "segments": [],
+            },
+        )
+        bot_id = append_and_apply(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "Quite well, thanks for asking!",
+                "truncated": False,
+                "user_turn_id": user_id,
+            },
+        )
+    return user_id, bot_id
+
+
+def test_t98_3_hide_turn_flips_event_log_hidden_via_manual_edit(
+    client, tmp_path
+):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+    user_id, bot_id = _seed_turns(db)
+
+    response = client.post(
+        f"/chats/chat_bot_a/drawer/turn/hide/{user_id}",
+        data={"hidden": "1"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        # event_log.hidden flipped to 1.
+        row = conn.execute(
+            "SELECT hidden FROM event_log WHERE id = ?", (user_id,)
+        ).fetchone()
+        assert int(row[0]) == 1
+
+        # manual_edit landed with the prior snapshot.
+        import json as _json
+
+        log = conn.execute(
+            "SELECT payload_json FROM event_log "
+            "WHERE kind = 'manual_edit' ORDER BY id DESC LIMIT 1"
+        ).fetchone()
+        payload = _json.loads(log[0])
+        assert payload["target_kind"] == "turn_hidden"
+        assert int(payload["target_id"]) == user_id
+        assert payload["prior_value"] == {"hidden": 0}
+        assert payload["new_value"] == {"hidden": 1}
+
+
+def test_t98_3_hidden_turn_disappears_from_read_recent_dialogue(
+    client, tmp_path
+):
+    """Hiding a turn must drop it from the prompt-window read.
+
+    ``read_recent_dialogue`` (chat.services.turn_common) filters
+    ``hidden = 0`` server-side, so flipping the flag via the drawer
+    route must surface immediately.
+    """
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+    user_id, bot_id = _seed_turns(db)
+
+    # Sanity baseline — both turns visible before the hide.
+    with open_db(db) as conn:
+        from chat.services.turn_common import read_recent_dialogue
+
+        before = read_recent_dialogue(conn, "chat_bot_a", limit=10)
+        before_ids = [t["event_id"] for t in before]
+        assert user_id in before_ids
+        assert bot_id in before_ids
+
+    # Hide the user turn via the drawer route.
+    response = client.post(
+        f"/chats/chat_bot_a/drawer/turn/hide/{user_id}",
+        data={"hidden": "1"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        from chat.services.turn_common import read_recent_dialogue
+
+        after = read_recent_dialogue(conn, "chat_bot_a", limit=10)
+        after_ids = [t["event_id"] for t in after]
+        assert user_id not in after_ids
+        assert bot_id in after_ids  # the unhidden bot turn still surfaces
+
+
+# ---------------------------------------------------------------------------
+# T98.4 — surgical delete with cascade preview.
+# ---------------------------------------------------------------------------
+
+
+def test_t98_4_delete_preview_returns_impact_report_html(client, tmp_path):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+    user_id, bot_id = _seed_turns(db)
+
+    response = client.get(
+        f"/chats/chat_bot_a/drawer/turn/delete-preview/{user_id}"
+    )
+    assert response.status_code == 200
+    body = response.text
+
+    # Modal markup with the event id and the cascade list.
+    assert "delete-impact-modal" in body
+    assert f"Delete event {user_id}?" in body
+    assert "delete-impact-cascade" in body
+    # Both turns ride along in the cascade — user_turn at user_id, then
+    # the assistant_turn at bot_id (>= user_id).
+    assert "user_turn" in body
+    assert "assistant_turn" in body
+    # Confirm-form posts to the delete route.
+    assert f"/drawer/turn/delete/{user_id}" in body
+
+
+def test_t98_4_delete_invokes_rewind_and_drops_cascade(client, tmp_path):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+    user_id, bot_id = _seed_turns(db)
+
+    # Append a third turn after the assistant_turn so we can verify the
+    # cascade catches everything from user_id forward.
+    with open_db(db) as conn:
+        extra_id = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "follow-up",
+                "segments": [],
+            },
+        )
+
+    # Sanity: all three turn rows exist.
+    with open_db(db) as conn:
+        turn_count = conn.execute(
+            "SELECT COUNT(*) FROM event_log "
+            "WHERE kind IN ('user_turn', 'assistant_turn')"
+        ).fetchone()[0]
+        assert turn_count == 3
+
+    # Delete from user_id forward.
+    response = client.post(f"/chats/chat_bot_a/drawer/turn/delete/{user_id}")
+    assert response.status_code == 200
+
+    # All three turns are gone — the rewind truncated the log past
+    # user_id - 1, removing user_id, bot_id, and extra_id.
+    with open_db(db) as conn:
+        turn_count = conn.execute(
+            "SELECT COUNT(*) FROM event_log "
+            "WHERE kind IN ('user_turn', 'assistant_turn')"
+        ).fetchone()[0]
+        assert turn_count == 0
+        for ev_id in (user_id, bot_id, extra_id):
+            row = conn.execute(
+                "SELECT 1 FROM event_log WHERE id = ?", (ev_id,)
+            ).fetchone()
+            assert row is None, f"event {ev_id} should have been deleted"
+
+
+# ---------------------------------------------------------------------------
+# T98.5 — remaining v1 edits (chat narrative anchor + weather).
+# ---------------------------------------------------------------------------
+
+
+def test_t98_5_edit_chat_narrative_anchor_emits_manual_edit(client, tmp_path):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+
+    response = client.post(
+        "/chats/chat_bot_a/drawer/chat/narrative-anchor",
+        data={"new_value": "Late evening, after dinner"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        row = conn.execute(
+            "SELECT narrative_anchor FROM chat_state WHERE chat_id = ?",
+            ("chat_bot_a",),
+        ).fetchone()
+        assert row[0] == "Late evening, after dinner"
+
+        import json as _json
+
+        log = conn.execute(
+            "SELECT payload_json FROM event_log "
+            "WHERE kind = 'manual_edit' ORDER BY id DESC LIMIT 1"
+        ).fetchone()
+        payload = _json.loads(log[0])
+        assert payload["target_kind"] == "chat_narrative_anchor"
+        assert payload["target_id"] == "chat_bot_a"
+        assert payload["prior_value"] == "Day 1"
+        assert payload["new_value"] == "Late evening, after dinner"
+
+
+def test_t98_5_edit_chat_weather_emits_manual_edit(client, tmp_path):
+    db = tmp_path / "test.db"
+    _seed_chat(db)
+
+    response = client.post(
+        "/chats/chat_bot_a/drawer/chat/weather",
+        data={"new_value": "thunderstorm rolling in"},
+    )
+    assert response.status_code == 200
+
+    with open_db(db) as conn:
+        row = conn.execute(
+            "SELECT weather FROM chat_state WHERE chat_id = ?",
+            ("chat_bot_a",),
+        ).fetchone()
+        assert row[0] == "thunderstorm rolling in"
+
+        import json as _json
+
+        log = conn.execute(
+            "SELECT payload_json FROM event_log "
+            "WHERE kind = 'manual_edit' ORDER BY id DESC LIMIT 1"
+        ).fetchone()
+        payload = _json.loads(log[0])
+        assert payload["target_kind"] == "chat_weather"
+        assert payload["target_id"] == "chat_bot_a"
+        assert payload["prior_value"] == ""
+        assert payload["new_value"] == "thunderstorm rolling in"

tests/test_embedding_worker.py

@@ -0,0 +1,185 @@
+"""Embedding worker (T97, Phase 4).
+
+The worker drains a queue of EmbeddingJobs and emits ``embedding_indexed``
+events. Mirrors test_significance.py's BackgroundWorker tests in shape:
+seed a memory, enqueue jobs, call ``stop()`` to drain via sentinel, then
+assert on the projected ``embeddings`` table and the underlying event_log.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+from chat.services.embedding_worker import EmbeddingJob, EmbeddingWorker
+from chat.services.embeddings import (
+    DEFAULT_EMBEDDING_MODEL,
+    EmbeddingResult,
+    FALLBACK_EMBEDDING_MODEL,
+)
+
+# Trigger handler registration for projection.
+import chat.state.embeddings  # noqa: F401
+import chat.state.entities  # noqa: F401
+import chat.state.memory  # noqa: F401
+import chat.state.world  # noqa: F401
+
+
+def _seed_memories(db_path: Path, count: int) -> list[int]:
+    """Seed ``count`` memory rows for ``bot_a`` and return their ids."""
+    with open_db(db_path) as conn:
+        append_event(
+            conn,
+            kind="bot_authored",
+            payload={
+                "id": "bot_a",
+                "name": "BotA",
+                "persona": "...",
+                "voice_samples": [],
+                "traits": [],
+                "backstory": "",
+                "initial_relationship_to_you": "",
+                "kickoff_prose": "",
+            },
+        )
+        append_event(
+            conn,
+            kind="chat_created",
+            payload={
+                "id": "chat_bot_a",
+                "host_bot_id": "bot_a",
+                "initial_time": "2026-04-26T20:00:00+00:00",
+                "narrative_anchor": "Day 1",
+                "weather": "",
+            },
+        )
+        for i in range(count):
+            append_event(
+                conn,
+                kind="memory_written",
+                payload={
+                    "owner_id": "bot_a",
+                    "chat_id": "chat_bot_a",
+                    "pov_summary": f"memory text {i}",
+                    "witness_you": 1,
+                    "witness_host": 1,
+                    "witness_guest": 0,
+                    "source": "direct",
+                    "reliability": 1.0,
+                    "significance": 1,
+                    "pinned": 0,
+                    "auto_pinned": 0,
+                },
+            )
+        project(conn)
+        return [
+            r[0]
+            for r in conn.execute(
+                "SELECT id FROM memories WHERE owner_id = 'bot_a' ORDER BY id"
+            ).fetchall()
+        ]
+
+
+async def test_worker_drains_jobs_and_emits_indexed_events(tmp_path):
+    """Three jobs in -> three ``embedding_indexed`` events out, all
+    projected into the ``embeddings`` table."""
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    memory_ids = _seed_memories(db, count=3)
+
+    worker = EmbeddingWorker(
+        conn_factory=lambda: open_db(db),
+        client=None,  # pseudo path — no client needed
+    )
+    await worker.start()
+    for mid in memory_ids:
+        worker.enqueue(EmbeddingJob(memory_id=mid, text=f"text-{mid}"))
+    await worker.stop()
+
+    with open_db(db) as conn:
+        # Three embedding_indexed events landed.
+        cur = conn.execute(
+            "SELECT COUNT(*) FROM event_log WHERE kind = 'embedding_indexed'"
+        )
+        assert cur.fetchone()[0] == 3
+        # Three rows in the embeddings table — one per memory.
+        cur = conn.execute(
+            "SELECT memory_id, model, dim FROM embeddings ORDER BY memory_id"
+        )
+        rows = cur.fetchall()
+        assert len(rows) == 3
+        for (mid, model, dim), expected_mid in zip(rows, memory_ids):
+            assert mid == expected_mid
+            assert model == DEFAULT_EMBEDDING_MODEL
+            assert dim > 0
+
+
+async def test_worker_skips_fallback_results(tmp_path, monkeypatch):
+    """A fallback EmbeddingResult must NOT produce an embedding_indexed
+    event — backfill can retry later when a real embedding is available."""
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    memory_ids = _seed_memories(db, count=1)
+
+    async def _fake_generate(client, *, text, model, dim, timeout_s=30.0):
+        return EmbeddingResult(
+            vector=[0.0] * dim, model=FALLBACK_EMBEDDING_MODEL, dim=dim
+        )
+
+    # Patch the symbol the worker resolved at import time.
+    import chat.services.embedding_worker as worker_mod
+
+    monkeypatch.setattr(worker_mod, "generate_embedding", _fake_generate)
+
+    worker = EmbeddingWorker(
+        conn_factory=lambda: open_db(db),
+        client=None,
+    )
+    await worker.start()
+    worker.enqueue(EmbeddingJob(memory_id=memory_ids[0], text="anything"))
+    await worker.stop()
+
+    with open_db(db) as conn:
+        cur = conn.execute(
+            "SELECT COUNT(*) FROM event_log WHERE kind = 'embedding_indexed'"
+        )
+        assert cur.fetchone()[0] == 0
+        cur = conn.execute("SELECT COUNT(*) FROM embeddings")
+        assert cur.fetchone()[0] == 0
+
+
+async def test_worker_handles_concurrent_jobs_serially(tmp_path):
+    """Five jobs queued back-to-back must process in FIFO order — the
+    single-task design respects the Featherless 2-conn cap (and keeps
+    event_log ordering deterministic)."""
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    memory_ids = _seed_memories(db, count=5)
+
+    worker = EmbeddingWorker(
+        conn_factory=lambda: open_db(db),
+        client=None,
+    )
+    await worker.start()
+    # Enqueue all five before yielding to the loop — exercises the queue
+    # rather than a one-at-a-time drain.
+    for mid in memory_ids:
+        worker.enqueue(EmbeddingJob(memory_id=mid, text=f"text-{mid}"))
+    await worker.stop()
+
+    with open_db(db) as conn:
+        # Events landed in enqueue order (FIFO).
+        cur = conn.execute(
+            "SELECT json_extract(payload_json, '$.memory_id') "
+            "FROM event_log WHERE kind = 'embedding_indexed' "
+            "ORDER BY id"
+        )
+        seen = [r[0] for r in cur.fetchall()]
+        assert seen == memory_ids
+
+        # All five embeddings projected.
+        cur = conn.execute("SELECT COUNT(*) FROM embeddings")
+        assert cur.fetchone()[0] == 5

tests/test_embeddings.py

@@ -0,0 +1,91 @@
+"""Tests for the embedding generation service (T91, Phase 4).
+
+Phase 4's first cut ships a deterministic local pseudo-embedding so the
+vector retrieval pipeline can land without an external embeddings API
+or a heavy local model dependency. These tests pin the contract:
+
+* the result has the right shape (vector length, ``dim`` metadata),
+* the default ``model`` string is reported back unchanged,
+* output is byte-identical for the same input (deterministic),
+* distinct inputs produce distinct vectors (so cosine actually
+  discriminates),
+* empty / whitespace-only input collapses to the ``"fallback"`` sentinel
+  with a zero vector — callers detect this and skip indexing,
+* the vector is unit-normalized so cosine similarity behaves.
+
+The pseudo path doesn't touch the LLMClient, so we pass an empty
+``MockLLMClient`` — any accidental call into it would raise
+``IndexError`` and surface as a regression.
+"""
+
+from __future__ import annotations
+
+import math
+
+import pytest
+
+from chat.llm.mock import MockLLMClient
+from chat.services.embeddings import (
+    DEFAULT_EMBEDDING_DIM,
+    DEFAULT_EMBEDDING_MODEL,
+    FALLBACK_EMBEDDING_MODEL,
+    EmbeddingResult,
+    generate_embedding,
+)
+
+
+def _client() -> MockLLMClient:
+    # Pseudo path never calls the client — empty canned list ensures any
+    # accidental call raises and surfaces the regression loudly.
+    return MockLLMClient(canned=[])
+
+
+@pytest.mark.asyncio
+async def test_generate_embedding_returns_vector_of_correct_dim():
+    result = await generate_embedding(_client(), text="hello")
+    assert isinstance(result, EmbeddingResult)
+    assert isinstance(result.vector, list)
+    assert len(result.vector) == DEFAULT_EMBEDDING_DIM == 384
+    assert result.dim == 384
+    assert all(isinstance(x, float) for x in result.vector)
+
+
+@pytest.mark.asyncio
+async def test_generate_embedding_returns_correct_model_metadata():
+    result = await generate_embedding(_client(), text="hello")
+    assert result.model == DEFAULT_EMBEDDING_MODEL == "pseudo-sha256-384"
+
+
+@pytest.mark.asyncio
+async def test_generate_embedding_is_deterministic():
+    a = await generate_embedding(_client(), text="hello world")
+    b = await generate_embedding(_client(), text="hello world")
+    assert a.vector == b.vector
+
+
+@pytest.mark.asyncio
+async def test_generate_embedding_distinct_text_produces_distinct_vectors():
+    a = await generate_embedding(_client(), text="hello world")
+    b = await generate_embedding(_client(), text="totally different content")
+    assert a.vector != b.vector
+    # Sanity-check cosine similarity — both vectors are unit-normalized,
+    # so this reduces to a plain dot product.
+    cosine = sum(x * y for x, y in zip(a.vector, b.vector))
+    assert cosine < 0.99
+
+
+@pytest.mark.asyncio
+async def test_generate_embedding_empty_text_returns_fallback():
+    for empty in ("", "   ", "\n\t"):
+        result = await generate_embedding(_client(), text=empty)
+        assert result.model == FALLBACK_EMBEDDING_MODEL == "fallback"
+        assert result.dim == DEFAULT_EMBEDDING_DIM
+        assert len(result.vector) == DEFAULT_EMBEDDING_DIM
+        assert all(x == 0.0 for x in result.vector)
+
+
+@pytest.mark.asyncio
+async def test_generate_embedding_unit_normalized():
+    result = await generate_embedding(_client(), text="some non-empty text")
+    norm_sq = sum(x * x for x in result.vector)
+    assert math.isclose(norm_sq, 1.0, abs_tol=1e-6)

tests/test_embeddings_state.py

@@ -0,0 +1,218 @@
+from __future__ import annotations
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+import chat.state.memory  # registers memory_written handler
+import chat.state.embeddings  # registers embedding handlers
+from chat.state.embeddings import get_embedding, list_embeddings_for_owner
+
+
+def _base_memory(**overrides):
+    payload = {
+        "owner_id": "bot_a",
+        "chat_id": "chat_bot_a",
+        "scene_id": 1,
+        "pov_summary": "She laughed at his joke about owls.",
+        "witness_you": 1,
+        "witness_host": 1,
+        "witness_guest": 0,
+        "chat_clock_at": "2026-04-26T10:00:00",
+        "source": "direct",
+        "reliability": 1.0,
+        "significance": 1,
+        "pinned": 0,
+        "auto_pinned": 0,
+    }
+    payload.update(overrides)
+    return payload
+
+
+def _vec(n: int = 384, base: float = 0.1) -> list[float]:
+    """Return a length-n float vector with predictable values for assertions."""
+    return [round(base + i * 0.001, 6) for i in range(n)]
+
+
+def test_embedding_indexed_inserts_row(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(conn, kind="memory_written", payload=_base_memory())
+        project(conn)
+        memory_id = conn.execute("SELECT id FROM memories").fetchone()[0]
+
+        vector = _vec(384, base=0.1)
+        append_event(
+            conn,
+            kind="embedding_indexed",
+            payload={
+                "memory_id": memory_id,
+                "vector": vector,
+                "model": "test-model",
+                "dim": 384,
+            },
+        )
+        project(conn)
+
+        emb = get_embedding(conn, memory_id)
+        assert emb is not None
+        assert emb["memory_id"] == memory_id
+        assert emb["vector"] == vector
+        assert emb["model"] == "test-model"
+        assert emb["dim"] == 384
+        assert emb["indexed_at"] is not None
+
+
+def test_embedding_deindexed_removes_row(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(conn, kind="memory_written", payload=_base_memory())
+        project(conn)
+        memory_id = conn.execute("SELECT id FROM memories").fetchone()[0]
+
+        append_event(
+            conn,
+            kind="embedding_indexed",
+            payload={
+                "memory_id": memory_id,
+                "vector": _vec(),
+                "model": "test-model",
+                "dim": 384,
+            },
+        )
+        project(conn)
+        assert get_embedding(conn, memory_id) is not None
+
+        append_event(
+            conn,
+            kind="embedding_deindexed",
+            payload={"memory_id": memory_id},
+        )
+        project(conn)
+        assert get_embedding(conn, memory_id) is None
+
+
+def test_embedding_indexed_replaces_existing(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        append_event(conn, kind="memory_written", payload=_base_memory())
+        project(conn)
+        memory_id = conn.execute("SELECT id FROM memories").fetchone()[0]
+
+        vec_a = _vec(384, base=0.1)
+        vec_b = _vec(384, base=0.5)
+        append_event(
+            conn,
+            kind="embedding_indexed",
+            payload={
+                "memory_id": memory_id,
+                "vector": vec_a,
+                "model": "test-model",
+                "dim": 384,
+            },
+        )
+        project(conn)
+        first = get_embedding(conn, memory_id)
+        assert first is not None
+        assert first["vector"] == vec_a
+
+        append_event(
+            conn,
+            kind="embedding_indexed",
+            payload={
+                "memory_id": memory_id,
+                "vector": vec_b,
+                "model": "test-model",
+                "dim": 384,
+            },
+        )
+        project(conn)
+        second = get_embedding(conn, memory_id)
+        assert second is not None
+        assert second["vector"] == vec_b
+        # Still exactly one row for this memory.
+        count = conn.execute(
+            "SELECT COUNT(*) FROM embeddings WHERE memory_id = ?", (memory_id,)
+        ).fetchone()[0]
+        assert count == 1
+
+
+def test_list_embeddings_for_owner_returns_joined_rows(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        # Two memories for bot_a, one for bot_b.
+        append_event(
+            conn,
+            kind="memory_written",
+            payload=_base_memory(
+                owner_id="bot_a",
+                pov_summary="Alpha memory.",
+                significance=2,
+            ),
+        )
+        append_event(
+            conn,
+            kind="memory_written",
+            payload=_base_memory(
+                owner_id="bot_a",
+                pov_summary="Beta memory.",
+                significance=3,
+            ),
+        )
+        append_event(
+            conn,
+            kind="memory_written",
+            payload=_base_memory(
+                owner_id="bot_b",
+                pov_summary="Gamma memory.",
+                significance=1,
+            ),
+        )
+        project(conn)
+
+        rows = conn.execute(
+            "SELECT id, owner_id FROM memories ORDER BY id"
+        ).fetchall()
+        # Index every memory with a distinct vector so we can check ordering.
+        for i, (mid, _owner) in enumerate(rows):
+            append_event(
+                conn,
+                kind="embedding_indexed",
+                payload={
+                    "memory_id": mid,
+                    "vector": _vec(384, base=0.1 * (i + 1)),
+                    "model": "test-model",
+                    "dim": 384,
+                },
+            )
+        project(conn)
+
+        a_rows = list_embeddings_for_owner(conn, "bot_a")
+        assert len(a_rows) == 2
+        summaries = {r["pov_summary"] for r in a_rows}
+        assert summaries == {"Alpha memory.", "Beta memory."}
+        sigs = {r["significance"] for r in a_rows}
+        assert sigs == {2, 3}
+        for r in a_rows:
+            assert r["model"] == "test-model"
+            assert r["dim"] == 384
+            assert isinstance(r["vector"], list)
+            assert len(r["vector"]) == 384
+            assert r["witness_you"] == 1
+            assert r["witness_host"] == 1
+            assert r["witness_guest"] == 0
+
+        b_rows = list_embeddings_for_owner(conn, "bot_b")
+        assert len(b_rows) == 1
+        assert b_rows[0]["pov_summary"] == "Gamma memory."
+
+
+def test_get_embedding_returns_none_when_missing(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        assert get_embedding(conn, 999) is None

tests/test_memory_search.py

@@ -16,6 +16,7 @@ from chat.eventlog.log import append_event
 from chat.eventlog.projector import project
 from chat.state.memory import search_memories
 import chat.state.memory  # noqa: F401  (registers memory_written handler)
+import chat.state.embeddings  # noqa: F401  (registers embedding_indexed handler)
 
 
 def _seed(db, *, memory_specs):
@@ -159,3 +160,216 @@ def test_significance_bias_is_constant_module_level():
     # Must be non-negative -- a negative bias would invert the desired
     # "higher significance ranks higher" semantics.
     assert SIGNIFICANCE_RANK_BIAS >= 0
+
+
+# ---------------------------------------------------------------------------
+# T96 (Phase 4): combined FTS + vector retrieval ranking via reciprocal-rank
+# fusion. The fused path activates only when ``query_vector`` is provided —
+# the no-vector path (above) is unchanged.
+# ---------------------------------------------------------------------------
+
+
+def _one_hot(dim: int, idx: int) -> list[float]:
+    v = [0.0] * dim
+    v[idx] = 1.0
+    return v
+
+
+def _seed_memories_with_optional_embeddings(db, *, memory_specs):
+    """Like ``_seed`` but also projects ``embedding_indexed`` events for any
+    spec carrying a ``vector`` key.
+
+    Memory rows are assigned ids in the order their ``memory_written`` events
+    were appended (the ``memories.id`` column is an autoincrementing primary
+    key), so we predict ``memory_id = i + 1`` per spec and append both kinds
+    of events back-to-back BEFORE projecting. Projecting only once keeps the
+    INSERT-based ``memory_written`` handler from duplicating rows.
+    """
+    apply_migrations(db)
+    with open_db(db) as conn:
+        # First pass: append every memory_written event in order. The DB
+        # assigns autoincrementing ids 1..N matching the order of these
+        # events, so we can pair vectors to memories by index.
+        for spec in memory_specs:
+            payload = {
+                "owner_id": spec.get("owner_id", "bot_a"),
+                "chat_id": spec.get("chat_id", "chat_bot_a"),
+                "pov_summary": spec["pov_summary"],
+                "witness_you": spec.get("witness_you", 1),
+                "witness_host": spec.get("witness_host", 1),
+                "witness_guest": spec.get("witness_guest", 0),
+                "source": "direct",
+                "reliability": 1.0,
+                "significance": spec.get("significance", 1),
+                "pinned": 0,
+                "auto_pinned": 0,
+            }
+            append_event(conn, kind="memory_written", payload=payload)
+        # Second pass: append embedding_indexed events for any spec that
+        # supplied a vector, using the predicted memory id.
+        for i, spec in enumerate(memory_specs, start=1):
+            if "vector" not in spec:
+                continue
+            vec = spec["vector"]
+            append_event(
+                conn,
+                kind="embedding_indexed",
+                payload={
+                    "memory_id": i,
+                    "vector": list(vec),
+                    "model": "test-model",
+                    "dim": len(vec),
+                },
+            )
+        # Single projection — avoids the memory_written handler INSERTing
+        # the same row twice on a re-projection.
+        project(conn)
+
+
+def test_search_memories_without_query_vector_uses_fts_only(tmp_path):
+    """Regression: omitting ``query_vector`` keeps the existing FTS-only path.
+
+    Identical seed to ``test_search_higher_significance_ranks_above_lower``
+    but pinned to the no-vector code path explicitly (no kwarg passed).
+    """
+    db = tmp_path / "t.db"
+    _seed(
+        db,
+        memory_specs=[
+            {"pov_summary": "small promise"},
+            {"pov_summary": "huge promise"},
+            {"pov_summary": "tiny promise", "significance": 3},
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_memories(conn, "bot_a", "host", "promise", k=3)
+        assert len(out) == 3
+        # The composite re-rank surfaces the high-significance row first.
+        assert out[0]["pov_summary"] == "tiny promise"
+        # Sanity: the row shape still carries ``fts_rank`` + ``composite_score``
+        # like the FTS-only path always has.
+        assert "fts_rank" in out[0]
+        assert "composite_score" in out[0]
+
+
+def test_search_memories_with_query_vector_includes_vector_hits(tmp_path):
+    """RRF fuses FTS hits with vector hits — both kinds surface in the result.
+
+    Memory 1 only matches FTS (keyword "rabbit", embedding far from query).
+    Memory 2 only matches the vector (embedding identical to query, no
+    keyword overlap). Memories 3-5 are unrelated. The fused top-K must
+    contain BOTH memory 1 and memory 2.
+    """
+    db = tmp_path / "t.db"
+    dim = 8
+    # Query vector = one-hot at index 0. Memory 2 mirrors it exactly. The
+    # FTS-only memory (memory 1) has NO embedding so it cannot leak into
+    # the vector ranking; the filler memories (3-5) likewise have no
+    # embeddings, so the vector ranking returns memory 2 alone.
+    query_vec = _one_hot(dim, 0)
+    _seed_memories_with_optional_embeddings(
+        db,
+        memory_specs=[
+            # Memory 1: FTS-only match. No embedding indexed.
+            {"pov_summary": "rabbit hopped over the fence"},
+            # Memory 2: vector-only match. No keyword overlap with "rabbit".
+            {
+                "pov_summary": "completely unrelated narrative line",
+                "vector": _one_hot(dim, 0),
+            },
+            # Memories 3-5: filler, irrelevant to both channels.
+            {"pov_summary": "lighthouse keeper polished the lens"},
+            {"pov_summary": "they discussed cartography for hours"},
+            {"pov_summary": "she taught him semaphore signals"},
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_memories(
+            conn,
+            "bot_a",
+            "host",
+            "rabbit",
+            k=4,
+            query_vector=query_vec,
+        )
+        summaries = [r["pov_summary"] for r in out]
+        # FTS-only candidate (memory 1) made it through.
+        assert "rabbit hopped over the fence" in summaries
+        # Vector-only candidate (memory 2) also made it through despite
+        # having no keyword overlap with the query string.
+        assert "completely unrelated narrative line" in summaries
+
+
+def test_search_memories_fusion_significance_bias_still_applies(tmp_path):
+    """With two RRF-tied candidates, the higher-significance one ranks first.
+
+    Two memories share the keyword "promise" AND share an identical
+    embedding to the query — so their FTS rank and vector rank are both
+    ties. RRF gives them the same fusion score. The Python-side
+    significance + recency boost must break the tie in favour of the
+    higher-significance memory.
+    """
+    db = tmp_path / "t.db"
+    dim = 4
+    shared_vec = _one_hot(dim, 0)
+    _seed_memories_with_optional_embeddings(
+        db,
+        memory_specs=[
+            {
+                "pov_summary": "she made a promise",
+                "significance": 0,
+                "vector": list(shared_vec),
+            },
+            {
+                "pov_summary": "she made a promise",
+                "significance": 3,
+                "vector": list(shared_vec),
+            },
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_memories(
+            conn,
+            "bot_a",
+            "host",
+            "promise",
+            k=2,
+            query_vector=list(shared_vec),
+        )
+        assert len(out) == 2
+        # Higher significance breaks the RRF tie.
+        assert out[0]["significance"] == 3
+        assert out[1]["significance"] == 0
+
+
+def test_search_memories_fusion_handles_empty_vector_results(tmp_path):
+    """Vector path returning [] (no embeddings indexed) must not break FTS.
+
+    No ``embedding_indexed`` events are projected, so ``vector_search``
+    returns an empty list. The function should still return the FTS hits
+    as if ``query_vector`` had not been supplied.
+    """
+    db = tmp_path / "t.db"
+    _seed(
+        db,
+        memory_specs=[
+            {"pov_summary": "the vault held an old promise"},
+            {"pov_summary": "another promise was kept that night"},
+        ],
+    )
+    with open_db(db) as conn:
+        out = search_memories(
+            conn,
+            "bot_a",
+            "host",
+            "promise",
+            k=4,
+            query_vector=[0.0] * 384,  # No embeddings exist for this owner.
+        )
+        # Both FTS hits still come back — no error from the empty vector path.
+        assert len(out) == 2
+        summaries = {r["pov_summary"] for r in out}
+        assert summaries == {
+            "the vault held an old promise",
+            "another promise was kept that night",
+        }

tests/test_memory_write.py

@@ -22,7 +22,7 @@ from chat.db.migrate import apply_migrations
 from chat.eventlog.log import append_event
 from chat.eventlog.projector import project
 from chat.llm.mock import MockLLMClient
-from chat.services.memory_write import record_turn_memory, record_turn_memory_for_present
+from chat.services.memory_write import record_turn_memory_for_present
 import chat.state.entities  # noqa: F401  - register handlers
 import chat.state.memory  # noqa: F401
 import chat.state.world  # noqa: F401
@@ -64,14 +64,19 @@ def test_record_turn_memory_writes_event_and_projects(tmp_path):
     apply_migrations(db)
     _seed_minimal(db)
     with open_db(db) as conn:
-        eid, mid = record_turn_memory(
+        # T90.3: legacy ``record_turn_memory`` was removed; the unified
+        # ``record_turn_memory_for_present`` with ``guest_bot_id=None``
+        # produces the same single-bot witness mask [1,1,0].
+        result = record_turn_memory_for_present(
             conn,
             chat_id="chat_bot_a",
             host_bot_id="bot_a",
+            guest_bot_id=None,
             narrative_text="BotA looks up. 'You're back late.'",
             scene_id=None,
             chat_clock_at="2026-04-26T20:00:00+00:00",
         )
+        eid, mid = result["bot_a"]
         assert eid > 0
         assert mid is not None and mid > 0
 
@@ -111,12 +116,15 @@ def test_record_turn_memory_omits_optional_fields(tmp_path):
     _seed_minimal(db)
     with open_db(db) as conn:
         # Call without scene_id/chat_clock_at — should default to None.
-        eid, mid = record_turn_memory(
+        # T90.3: migrated from legacy ``record_turn_memory``.
+        result = record_turn_memory_for_present(
             conn,
             chat_id="chat_bot_a",
             host_bot_id="bot_a",
+            guest_bot_id=None,
             narrative_text="A simple memory.",
         )
+        eid, mid = result["bot_a"]
         assert eid > 0
         assert mid is not None and mid > 0
 
@@ -532,3 +540,49 @@ def test_record_turn_memory_you_present_false_requires_guest(tmp_path):
                 narrative_text="invalid",
                 you_present=False,
             )
+
+
+# ---------------------------------------------------------------------------
+# T97: embedding-worker enqueue hook.
+# ---------------------------------------------------------------------------
+
+
+def test_record_turn_memory_enqueues_embedding_job(tmp_path):
+    """When ``app.state.embedding_worker`` is wired, every per-witness
+    write enqueues an :class:`EmbeddingJob` carrying the freshly-projected
+    memory id and the narrative text. Two-bot turn -> two jobs."""
+    from types import SimpleNamespace
+
+    from chat.services.embedding_worker import EmbeddingJob
+
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    _seed_two_bots(db)
+
+    captured: list[EmbeddingJob] = []
+
+    class _StubWorker:
+        def enqueue(self, job: EmbeddingJob) -> None:
+            captured.append(job)
+
+    fake_app = SimpleNamespace(
+        state=SimpleNamespace(embedding_worker=_StubWorker())
+    )
+
+    with open_db(db) as conn:
+        result = record_turn_memory_for_present(
+            conn,
+            chat_id="chat_ab",
+            host_bot_id="bot_a",
+            guest_bot_id="bot_b",
+            narrative_text="Both bots witness this beat.",
+            app=fake_app,
+        )
+
+    # One job per witness — host first, then guest (matches result dict
+    # insertion order in record_turn_memory_for_present).
+    assert len(captured) == 2
+    expected_ids = {result["bot_a"][1], result["bot_b"][1]}
+    assert {job.memory_id for job in captured} == expected_ids
+    for job in captured:
+        assert job.text == "Both bots witness this beat."

tests/test_phase4_integration.py

@@ -0,0 +1,891 @@
+"""Phase 4 cross-feature integration tests (T97 follow-up + T101).
+
+Cross-feature flows for the Phase 4 retrieval + branching + drawer
+features. Each test drives multiple Phase 4 surfaces end-to-end and
+asserts both event_log and projected-state outcomes.
+
+Test inventory:
+
+* ``test_post_turn_embeddings_indexed_via_worker_hook`` (T97.5) —
+  pins the production turn route's ``app=request.app`` plumbing so
+  the embedding worker actually receives jobs.
+
+T101 additions (the "Phase 4 cross-feature integration" suite):
+
+1. ``test_vector_retrieval_feedback_loop`` — write a memory, drain
+   the embedding worker, assert the vector path retrieves it.
+2. ``test_branch_diverge_main_intact`` — create a branch from a
+   mid-log turn, switch, append more events, switch back and assert
+   the original log past the branch point is still present (Phase 4
+   branching is metadata-only — no read-side filter yet).
+3. ``test_surgical_delete_truncates_log_and_writes_snapshot`` —
+   compute impact, confirm via the drawer route, assert the log was
+   truncated and a pre-rewind snapshot landed on disk.
+4. ``test_hide_then_unhide_round_trip_through_read_recent_dialogue``
+   — flip ``hidden`` via the drawer route both directions and assert
+   ``read_recent_dialogue`` honours the flag in real time.
+5. ``test_cross_chat_search_surfaces_memories_in_three_chats`` —
+   write memories in 3 chats, hit ``/search?q=...`` and assert all
+   three appear.
+
+The T97.5 test monkeypatches ``app.state.embedding_worker.enqueue`` to
+record jobs (rather than draining the worker) because the bug it pins
+is "did the call site pass ``app`` at all". T101 test 1 takes the
+opposite tack: it drives the worker for real to verify the entire
+write -> index -> retrieve loop.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+from fastapi.testclient import TestClient
+
+from chat.app import app
+from chat.db.connection import open_db
+from chat.eventlog.log import append_and_apply, append_event
+from chat.eventlog.projector import project
+from chat.llm.mock import MockLLMClient
+
+
+def _zero_state() -> str:
+    return json.dumps(
+        {"affinity_delta": 0, "trust_delta": 0, "knowledge_facts": []}
+    )
+
+
+def _override_llm(canned: list[str]) -> MockLLMClient:
+    from chat.web.kickoff import get_llm_client
+
+    mock = MockLLMClient(canned=list(canned))
+    app.dependency_overrides[get_llm_client] = lambda: mock
+    return mock
+
+
+@pytest.fixture
+def app_state_setup(tmp_path, monkeypatch):
+    cfg = tmp_path / "config.toml"
+    cfg.write_text('featherless_api_key = "test"\n')
+    monkeypatch.setenv("CHAT_CONFIG_PATH", str(cfg))
+    db = tmp_path / "test.db"
+    monkeypatch.setenv("CHAT_DB_PATH", str(db))
+    with TestClient(app) as c:
+        # The background worker is disabled so the canned-response queue
+        # is consumed only by the request path. The embedding worker
+        # stays "started" but its loop won't observe the captured
+        # enqueues — we replace ``enqueue`` on the worker instance below.
+        app.state.background_worker.enabled = False
+        yield c
+    app.dependency_overrides.clear()
+
+
+def _seed(db_path: Path) -> None:
+    """Mirror of ``tests/test_turn_flow.py::_seed`` — single bot + chat
+    + edge + activities so the prompt assembler has something to render.
+    """
+    with open_db(db_path) as conn:
+        append_event(
+            conn,
+            kind="bot_authored",
+            payload={
+                "id": "bot_a",
+                "name": "BotA",
+                "persona": "thoughtful, observant",
+                "voice_samples": [],
+                "traits": [],
+                "backstory": "",
+                "initial_relationship_to_you": "",
+                "kickoff_prose": "...",
+            },
+        )
+        append_event(
+            conn,
+            kind="chat_created",
+            payload={
+                "id": "chat_bot_a",
+                "host_bot_id": "bot_a",
+                "initial_time": "2026-04-26T20:00:00+00:00",
+                "narrative_anchor": "Day 1",
+                "weather": "",
+            },
+        )
+        append_event(
+            conn,
+            kind="edge_update",
+            payload={
+                "source_id": "bot_a",
+                "target_id": "you",
+                "chat_id": "chat_bot_a",
+                "knowledge_facts": ["coworker"],
+            },
+        )
+        for entity_id, verb in [("you", "talking"), ("bot_a", "listening")]:
+            append_event(
+                conn,
+                kind="activity_change",
+                payload={
+                    "entity_id": entity_id,
+                    "posture": "sitting",
+                    "action": {
+                        "verb": verb,
+                        "interruptible": True,
+                        "required_attention": "low",
+                        "expected_duration": "ongoing",
+                    },
+                    "attention": "",
+                    "holding": [],
+                    "status": {},
+                },
+            )
+        project(conn)
+
+
+def test_post_turn_embeddings_indexed_via_worker_hook(
+    app_state_setup, tmp_path
+):
+    """POST a turn; the route must pass ``app=request.app`` into
+    ``record_turn_memory_for_present`` so the per-witness write enqueues
+    an :class:`EmbeddingJob` on ``app.state.embedding_worker``.
+
+    Without the T97.5 wiring this test fails: the call site previously
+    omitted ``app=`` and the helper's ``app is None`` branch silently
+    skipped every enqueue. We monkeypatch ``enqueue`` on the live
+    embedding worker (rather than draining the queue mid-request) so the
+    assertion does not depend on asyncio scheduling inside the
+    TestClient — the bug is in the wiring, and the wiring is what we
+    pin. The drain path is covered separately in
+    :mod:`tests.test_embedding_worker`.
+    """
+    _seed(tmp_path / "test.db")
+
+    canned_parse = json.dumps(
+        {"segments": [{"kind": "dialogue", "text": "hello"}]}
+    )
+    _override_llm(
+        [canned_parse, "Hi there.", _zero_state(), _zero_state()]
+    )
+
+    captured: list = []
+    worker = app.state.embedding_worker
+    original_enqueue = worker.enqueue
+    worker.enqueue = captured.append  # type: ignore[assignment]
+    try:
+        response = app_state_setup.post(
+            "/chats/chat_bot_a/turns", data={"prose": "hello"}
+        )
+        assert response.status_code == 204
+    finally:
+        worker.enqueue = original_enqueue  # type: ignore[assignment]
+        app.dependency_overrides.clear()
+
+    # Single-bot turn -> one ``memory_written`` -> one EmbeddingJob.
+    # The job's ``memory_id`` should match the freshly-projected memory
+    # row, and its ``text`` should carry the assistant's narrative text.
+    assert len(captured) == 1
+    job = captured[0]
+    assert job.text == "Hi there."
+
+    with open_db(tmp_path / "test.db") as conn:
+        memory_ids = [
+            r[0]
+            for r in conn.execute(
+                "SELECT id FROM memories WHERE owner_id = ?",
+                ("bot_a",),
+            ).fetchall()
+        ]
+    assert job.memory_id in memory_ids
+
+
+# ---------------------------------------------------------------------------
+# T101 — Phase 4 cross-feature integration suite.
+# ---------------------------------------------------------------------------
+#
+# Helpers + the five required scenarios. Each test drives multiple Phase 4
+# features so a regression in any one of them fails an integration check.
+
+
+def _seed_minimal_chat(db_path: Path, chat_id: str = "chat_bot_a") -> None:
+    """Seed bot_a, you, a chat, edges, and activities — same shape as
+    ``tests/test_phase3_integration.py::_seed_single_bot_chat`` but
+    parameterised on chat_id so the cross-chat search test can stamp
+    several chats in the same database without renaming bots.
+
+    Uses ``append_and_apply`` rather than ``append_event`` + a final
+    ``project`` so successive calls (e.g. one per chat in the
+    cross-chat-search test) don't try to re-project the cumulative
+    log and trip the ``chats.id`` UNIQUE constraint on the prior
+    chat's row.
+    """
+    with open_db(db_path) as conn:
+        existing_bot = conn.execute(
+            "SELECT 1 FROM bots WHERE id = 'bot_a'"
+        ).fetchone()
+        if existing_bot is None:
+            append_and_apply(
+                conn,
+                kind="bot_authored",
+                payload={
+                    "id": "bot_a",
+                    "name": "BotA",
+                    "persona": "thoughtful",
+                    "voice_samples": [],
+                    "traits": [],
+                    "backstory": "",
+                    "initial_relationship_to_you": "",
+                    "kickoff_prose": "...",
+                },
+            )
+            append_and_apply(
+                conn,
+                kind="you_authored",
+                payload={
+                    "name": "Me",
+                    "pronouns": "they/them",
+                    "persona": "",
+                },
+            )
+        append_and_apply(
+            conn,
+            kind="chat_created",
+            payload={
+                "id": chat_id,
+                "host_bot_id": "bot_a",
+                "initial_time": "2026-04-26T20:00:00+00:00",
+                "narrative_anchor": "Day 1",
+                "weather": "",
+            },
+        )
+        append_and_apply(
+            conn,
+            kind="edge_update",
+            payload={
+                "source_id": "bot_a",
+                "target_id": "you",
+                "chat_id": chat_id,
+                "knowledge_facts": [],
+            },
+        )
+        # Activities are unique per (entity_id) — only seed them on the
+        # first call (when the bot row is also fresh).
+        if existing_bot is None:
+            for entity_id, verb in [
+                ("you", "talking"),
+                ("bot_a", "listening"),
+            ]:
+                append_and_apply(
+                    conn,
+                    kind="activity_change",
+                    payload={
+                        "entity_id": entity_id,
+                        "posture": "sitting",
+                        "action": {
+                            "verb": verb,
+                            "interruptible": True,
+                            "required_attention": "low",
+                            "expected_duration": "ongoing",
+                        },
+                        "attention": "",
+                        "holding": [],
+                        "status": {},
+                    },
+                )
+
+
+# ---------------------------------------------------------------------------
+# 1. Vector retrieval feedback loop.
+# ---------------------------------------------------------------------------
+
+
+async def test_vector_retrieval_feedback_loop(tmp_path):
+    """End-to-end: write a memory through
+    :func:`record_turn_memory_for_present` so an :class:`EmbeddingJob`
+    lands on a worker, drain the worker, then call
+    :func:`vector_search` with the SAME pseudo-embedding function and
+    assert the just-written memory is the top hit.
+
+    Why this test does NOT use the TestClient fixture: the live
+    ``app.state.embedding_worker`` is created inside the FastAPI
+    lifespan's event loop. ``await``-ing on it from pytest-asyncio's
+    loop trips ``"got Future attached to a different loop"``. We
+    instead spin up a fresh :class:`EmbeddingWorker` in the test
+    loop, exactly mirroring ``tests/test_embedding_worker.py``'s
+    pattern. The T97.5 test above pins the wiring between the live
+    HTTP route and the live app worker; this test pins the
+    write -> index -> retrieve loop with no transport in scope.
+
+    Cross-feature gaps this test catches:
+    * Memory write enqueues to the worker but the worker never
+      drains (e.g. ``_run`` deadlock or sentinel mishandled).
+    * Worker uses a different embedding function than
+      ``vector_search`` at query time, producing different vectors
+      and breaking cosine retrieval.
+    * ``embeddings`` projector handler is not registered (e.g.
+      import ordering bug) so the event fires but the table stays
+      empty.
+    """
+    from types import SimpleNamespace
+
+    from chat.db.migrate import apply_migrations
+    from chat.services.embedding_worker import EmbeddingWorker
+    from chat.services.embeddings import generate_embedding
+    from chat.services.memory_write import record_turn_memory_for_present
+    from chat.services.vector_search import vector_search
+
+    # Trigger projector handler registration. ``record_turn_memory_for_present``
+    # imports memory_write which imports the worker module, but the
+    # projector handlers live in ``chat.state.*`` modules and are
+    # registered as a side effect of import.
+    import chat.state.embeddings  # noqa: F401
+    import chat.state.entities  # noqa: F401
+    import chat.state.memory  # noqa: F401
+    import chat.state.world  # noqa: F401
+
+    db = tmp_path / "test.db"
+    apply_migrations(db)
+    _seed_minimal_chat(db)
+
+    # Spin up our own worker in the test event loop. ``client=None``
+    # is fine for the pseudo-embedding path — the local hash function
+    # does not require an LLM client.
+    worker = EmbeddingWorker(
+        conn_factory=lambda: open_db(db),
+        client=None,
+    )
+    await worker.start()
+
+    # Stub ``app`` — only ``app.state.embedding_worker`` is read by
+    # ``_write_one_memory``. SimpleNamespace gives us a stand-in that
+    # exposes ``state.embedding_worker`` without the full FastAPI app.
+    fake_app = SimpleNamespace(state=SimpleNamespace(embedding_worker=worker))
+
+    distinctive_text = "Maya watched the gondola lights drift across the lagoon."
+    with open_db(db) as conn:
+        record_turn_memory_for_present(
+            conn,
+            chat_id="chat_bot_a",
+            host_bot_id="bot_a",
+            guest_bot_id=None,
+            narrative_text=distinctive_text,
+            app=fake_app,
+        )
+
+    # Drain the worker via the sentinel. After this returns the
+    # ``embedding_indexed`` event has been projected.
+    await worker.stop()
+
+    # Generate a query embedding using the same function the worker
+    # used. The pseudo-embedding is deterministic so a query equal to
+    # the indexed text produces the identical vector and a cosine
+    # similarity of 1.0.
+    query_result = await generate_embedding(client=None, text=distinctive_text)
+
+    with open_db(db) as conn:
+        emb_count = conn.execute(
+            "SELECT COUNT(*) FROM embeddings"
+        ).fetchone()[0]
+        assert emb_count == 1, (
+            "embedding worker did not project an embedding_indexed event"
+        )
+
+        hits = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="host",  # bot_a is host, witness_host=1 by default
+            query_vector=query_result.vector,
+            k=4,
+        )
+        assert len(hits) == 1
+        top = hits[0]
+        assert top["pov_summary"] == distinctive_text
+        # Self-match: cosine of identical vectors is 1.0.
+        assert top["score"] == pytest.approx(1.0, abs=1e-9)
+
+
+# ---------------------------------------------------------------------------
+# 2. Branch + diverge: main's post-branch tail stays intact (Phase 4
+#    branches are metadata-only).
+# ---------------------------------------------------------------------------
+
+
+def test_branch_diverge_main_intact(app_state_setup, tmp_path):
+    """Append turns 1-12 on main, branch from turn 10's event_id, switch
+    to the new branch, append 3 more "play" turns, switch back to main,
+    assert the original turn 11+ events are untouched.
+
+    Phase 4's branches table is metadata-only — the read-side filter
+    isn't wired yet, so all events live in one log regardless of which
+    branch is "active". This test pins that contract: switching does
+    not mutate or hide existing events on either branch.
+
+    Canned LLM queue: none. ``user_turn`` / ``assistant_turn`` are
+    transcript-only kinds with no projector handler that needs an
+    LLM call, and ``branch_created`` / ``branch_switched`` are pure
+    state events. We use ``append_and_apply`` directly rather than
+    driving the HTTP turn route, which would require a 6-slot canned
+    queue per turn (parse + narrative + 2 state-updates + scene-close
+    + memory) for 15 turns total = 90 slots of plumbing irrelevant to
+    the branch contract.
+    """
+    from chat.services.branching import branch_from_event, switch_active_branch
+    from chat.state.branches import active_branch
+
+    db = tmp_path / "test.db"
+    _seed_minimal_chat(db)
+
+    # Append 12 user_turn / assistant_turn pairs on main. We collect
+    # the assistant_turn id at index 10 (1-based: "turn 10") so the
+    # branch fork point is unambiguous.
+    main_turn_ids: list[int] = []
+    with open_db(db) as conn:
+        for i in range(1, 13):
+            user_id = append_and_apply(
+                conn,
+                kind="user_turn",
+                payload={
+                    "chat_id": "chat_bot_a",
+                    "prose": f"main turn {i}",
+                    "segments": [],
+                },
+            )
+            asst_id = append_and_apply(
+                conn,
+                kind="assistant_turn",
+                payload={
+                    "chat_id": "chat_bot_a",
+                    "speaker_id": "bot_a",
+                    "text": f"main reply {i}",
+                    "truncated": False,
+                    "user_turn_id": user_id,
+                },
+            )
+            main_turn_ids.append(asst_id)
+        turn_10_id = main_turn_ids[9]
+
+        # Snapshot the post-turn-10 main tail (turns 11, 12 + their
+        # user_turn predecessors) so we can byte-compare after the
+        # round-trip.
+        main_tail_before = conn.execute(
+            "SELECT id, kind, payload_json, hidden, superseded_by "
+            "FROM event_log WHERE id > ? ORDER BY id",
+            (turn_10_id,),
+        ).fetchall()
+        assert len(main_tail_before) == 4  # 2 user + 2 assistant past turn 10
+
+        # Branch from turn 10. Phase 4's helper validates the origin
+        # event id exists and emits ``branch_created``.
+        branch_from_event(
+            conn,
+            name="experiment",
+            origin_event_id=turn_10_id,
+            chat_id="chat_bot_a",
+        )
+        switch_active_branch(conn, name="experiment")
+        active = active_branch(conn)
+        assert active is not None and active["name"] == "experiment"
+
+        # Play 3 turns on the experiment branch.
+        for i in range(1, 4):
+            user_id = append_and_apply(
+                conn,
+                kind="user_turn",
+                payload={
+                    "chat_id": "chat_bot_a",
+                    "prose": f"experiment turn {i}",
+                    "segments": [],
+                },
+            )
+            append_and_apply(
+                conn,
+                kind="assistant_turn",
+                payload={
+                    "chat_id": "chat_bot_a",
+                    "speaker_id": "bot_a",
+                    "text": f"experiment reply {i}",
+                    "truncated": False,
+                    "user_turn_id": user_id,
+                },
+            )
+
+        # Switch back to main.
+        switch_active_branch(conn, name="main")
+        active2 = active_branch(conn)
+        assert active2 is not None and active2["name"] == "main"
+
+        # Main's original tail past turn 10 is byte-identical: the
+        # branching events (branch_created, branch_switched x2) and the
+        # 3 experiment turns sit AFTER the original tail in event_log
+        # order, never overwriting it.
+        main_tail_after = conn.execute(
+            "SELECT id, kind, payload_json, hidden, superseded_by "
+            "FROM event_log "
+            "WHERE id > ? AND id <= ? ORDER BY id",
+            (turn_10_id, main_turn_ids[-1]),
+        ).fetchall()
+        assert main_tail_after == main_tail_before
+
+        # The 6 experiment events (3 user + 3 assistant) all live in
+        # the same log past the original main tail. Verify their
+        # prose payloads to disambiguate from main's content.
+        diverged = conn.execute(
+            "SELECT kind, json_extract(payload_json, '$.prose'), "
+            "  json_extract(payload_json, '$.text') "
+            "FROM event_log WHERE id > ? "
+            "  AND kind IN ('user_turn', 'assistant_turn') ORDER BY id",
+            (main_turn_ids[-1],),
+        ).fetchall()
+        assert len(diverged) == 6
+        prose_or_text = [(row[1] or row[2]) for row in diverged]
+        # Sequence: user1, asst1, user2, asst2, user3, asst3.
+        assert "experiment turn 1" in prose_or_text
+        assert "experiment reply 1" in prose_or_text
+        assert "experiment turn 3" in prose_or_text
+        assert "experiment reply 3" in prose_or_text
+
+
+# ---------------------------------------------------------------------------
+# 3. Surgical delete: impact preview -> confirm -> log truncated +
+#    pre-rewind snapshot saved.
+# ---------------------------------------------------------------------------
+
+
+def test_surgical_delete_truncates_log_and_writes_snapshot(
+    app_state_setup, tmp_path
+):
+    """Compute the delete-impact for a turn (read-only preview), then
+    confirm via the POST drawer route. Assert:
+
+    * The preview returns 200 + cascade markup.
+    * The event_log is physically truncated past ``target_id - 1``.
+    * A snapshot file lands under ``<data_dir>/snapshots/rewind/``.
+    * The pre-rewind snapshot's ``last_event_id`` matches the high
+      water mark BEFORE the truncate (so recovery can replay back to
+      pre-delete state).
+
+    Snapshot location: T97.5's ``data_dir`` derives from the db's
+    parent directory when ``CHAT_DATA_DIR`` is unset. The fixture
+    sets ``CHAT_DB_PATH = tmp_path / "test.db"`` so the snapshot
+    parent is ``tmp_path / "snapshots" / "rewind"``.
+
+    No canned LLM queue — the preview is pure SQL and the rewind path
+    is also pure SQL (delete + reproject). The drawer routes don't
+    invoke the LLM.
+    """
+    import json as _json
+
+    db = tmp_path / "test.db"
+    _seed_minimal_chat(db)
+
+    # Append a small fixed turn sequence we can predict the cascade for.
+    with open_db(db) as conn:
+        first_user = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "first message",
+                "segments": [],
+            },
+        )
+        append_and_apply(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "first reply",
+                "truncated": False,
+                "user_turn_id": first_user,
+            },
+        )
+        target_user = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "this turn will be deleted",
+                "segments": [],
+            },
+        )
+        target_asst = append_and_apply(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "and so will this reply",
+                "truncated": False,
+                "user_turn_id": target_user,
+            },
+        )
+        # One trailing event past the target so we can verify the
+        # cascade catches >1 event.
+        trailing = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "trailing context",
+                "segments": [],
+            },
+        )
+        max_id_before = conn.execute(
+            "SELECT MAX(id) FROM event_log"
+        ).fetchone()[0]
+
+    # ---- Preview: GET delete-preview returns 200 + the cascade list. ----
+    preview = app_state_setup.get(
+        f"/chats/chat_bot_a/drawer/turn/delete-preview/{target_user}"
+    )
+    assert preview.status_code == 200
+    body = preview.text
+    assert "delete-impact-modal" in body
+    assert f"Delete event {target_user}?" in body
+    assert "user_turn" in body
+    assert "assistant_turn" in body
+    # Confirm form points at the delete route.
+    assert f"/drawer/turn/delete/{target_user}" in body
+
+    # ---- Confirm: POST delete drops user, assistant, AND trailing. ----
+    confirm = app_state_setup.post(
+        f"/chats/chat_bot_a/drawer/turn/delete/{target_user}"
+    )
+    assert confirm.status_code == 200
+
+    # ---- Event log truncated past target_user - 1. ----
+    with open_db(db) as conn:
+        max_id_after = conn.execute(
+            "SELECT MAX(id) FROM event_log"
+        ).fetchone()[0]
+        # delete_turn passes ``after_event_id = target_user - 1`` so
+        # everything from target_user forward is gone.
+        assert max_id_after == target_user - 1
+        for ev_id in (target_user, target_asst, trailing):
+            row = conn.execute(
+                "SELECT 1 FROM event_log WHERE id = ?", (ev_id,)
+            ).fetchone()
+            assert row is None, f"event {ev_id} should have been deleted"
+
+    # ---- Pre-rewind snapshot landed on disk. ----
+    snapshot_dir = tmp_path / "snapshots" / "rewind"
+    assert snapshot_dir.exists(), (
+        f"snapshot dir not created: {snapshot_dir}"
+    )
+    snapshots = sorted(snapshot_dir.glob("*.json"))
+    assert len(snapshots) >= 1, (
+        f"no rewind snapshot written under {snapshot_dir}"
+    )
+    # Most-recent snapshot's last_event_id == pre-truncate high water
+    # mark, so a "restore" path could fully reverse the delete.
+    latest_snapshot = snapshots[-1]
+    snap_data = _json.loads(latest_snapshot.read_text())
+    assert snap_data["last_event_id"] == max_id_before
+
+
+# ---------------------------------------------------------------------------
+# 4. Hide + retrieval: drawer hide drops a turn from read_recent_dialogue,
+#    unhide restores it.
+# ---------------------------------------------------------------------------
+
+
+def test_hide_then_unhide_round_trip_through_read_recent_dialogue(
+    app_state_setup, tmp_path
+):
+    """Drive a hide -> read -> unhide -> read cycle through the drawer
+    HTTP route and assert ``read_recent_dialogue`` flips visibility
+    each step. T98.3 wires the route; T55 / turn_common owns the
+    ``hidden = 0`` filter.
+
+    Cross-feature: the drawer HTTP handler emits a ``manual_edit``
+    event with branch ``turn_hidden``, the manual_edit projector
+    flips ``event_log.hidden``, and the prompt-window reader filters
+    on that column. Three layers — any one breaking would fail this
+    test.
+
+    No canned LLM queue — hide/unhide are pure SQL routes.
+    """
+    from chat.services.turn_common import read_recent_dialogue
+
+    db = tmp_path / "test.db"
+    _seed_minimal_chat(db)
+
+    with open_db(db) as conn:
+        user_a = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "first user line",
+                "segments": [],
+            },
+        )
+        asst_a = append_and_apply(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "first reply",
+                "truncated": False,
+                "user_turn_id": user_a,
+            },
+        )
+        user_b = append_and_apply(
+            conn,
+            kind="user_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "prose": "second user line",
+                "segments": [],
+            },
+        )
+        asst_b = append_and_apply(
+            conn,
+            kind="assistant_turn",
+            payload={
+                "chat_id": "chat_bot_a",
+                "speaker_id": "bot_a",
+                "text": "second reply",
+                "truncated": False,
+                "user_turn_id": user_b,
+            },
+        )
+
+        # Baseline: all 4 turns visible.
+        baseline = read_recent_dialogue(conn, "chat_bot_a", limit=10)
+        baseline_ids = {t["event_id"] for t in baseline}
+        assert {user_a, asst_a, user_b, asst_b} <= baseline_ids
+
+    # ---- Hide user_b via the drawer route. ----
+    hide_resp = app_state_setup.post(
+        f"/chats/chat_bot_a/drawer/turn/hide/{user_b}",
+        data={"hidden": "1"},
+    )
+    assert hide_resp.status_code == 200
+
+    with open_db(db) as conn:
+        # event_log.hidden flipped.
+        row = conn.execute(
+            "SELECT hidden FROM event_log WHERE id = ?", (user_b,)
+        ).fetchone()
+        assert int(row[0]) == 1
+
+        # read_recent_dialogue drops user_b but keeps the others.
+        after_hide = read_recent_dialogue(conn, "chat_bot_a", limit=10)
+        after_hide_ids = {t["event_id"] for t in after_hide}
+        assert user_b not in after_hide_ids
+        # The other 3 turns still surface.
+        assert {user_a, asst_a, asst_b} <= after_hide_ids
+
+    # ---- Unhide via the SAME route with hidden=0. ----
+    unhide_resp = app_state_setup.post(
+        f"/chats/chat_bot_a/drawer/turn/hide/{user_b}",
+        data={"hidden": "0"},
+    )
+    assert unhide_resp.status_code == 200
+
+    with open_db(db) as conn:
+        row = conn.execute(
+            "SELECT hidden FROM event_log WHERE id = ?", (user_b,)
+        ).fetchone()
+        assert int(row[0]) == 0
+
+        # read_recent_dialogue restores user_b.
+        after_unhide = read_recent_dialogue(conn, "chat_bot_a", limit=10)
+        after_unhide_ids = {t["event_id"] for t in after_unhide}
+        assert {user_a, asst_a, user_b, asst_b} <= after_unhide_ids
+
+        # Two manual_edit events landed (one per toggle), each with the
+        # turn_hidden branch tag.
+        edits = conn.execute(
+            "SELECT payload_json FROM event_log "
+            "WHERE kind = 'manual_edit' "
+            "  AND json_extract(payload_json, '$.target_kind') = 'turn_hidden' "
+            "ORDER BY id"
+        ).fetchall()
+        assert len(edits) == 2
+
+
+# ---------------------------------------------------------------------------
+# 5. Cross-chat search: memories across 3 chats all surface from /search.
+# ---------------------------------------------------------------------------
+
+
+def test_cross_chat_search_surfaces_memories_in_three_chats(
+    app_state_setup, tmp_path
+):
+    """Seed 3 chats each owned by bot_a (so the bot row exists for the
+    search route's display-name hydration), write a distinctive
+    memory in each, then GET ``/search?q=<distinctive>`` and assert
+    every chat appears as a result row.
+
+    Cross-feature: T93's :func:`search_all_memories` (no per-owner
+    filter) + T100's HTML route (display-name hydration via
+    ``get_bot``/``get_chat``). The route's empty-query short-circuit
+    is incidentally exercised by the request setup but isn't the
+    focus.
+
+    No canned LLM queue — memory_written events are projected directly
+    via ``append_and_apply`` and the search route is pure SQL +
+    template rendering.
+    """
+    db = tmp_path / "test.db"
+    # Three chats, all hosted by bot_a so bot_a is the owner of all
+    # three memories. _seed_minimal_chat skips the bot/you bootstrap
+    # after the first call so the cumulative seed is consistent.
+    chat_ids = ["chat_bot_a", "chat_bot_a_2", "chat_bot_a_3"]
+    for chat_id in chat_ids:
+        _seed_minimal_chat(db, chat_id=chat_id)
+
+    # Distinctive token — "wisteria" appears nowhere else in the seed.
+    distinctive = "wisteria"
+    with open_db(db) as conn:
+        for idx, chat_id in enumerate(chat_ids):
+            append_and_apply(
+                conn,
+                kind="memory_written",
+                payload={
+                    "owner_id": "bot_a",
+                    "chat_id": chat_id,
+                    "pov_summary": (
+                        f"the {distinctive} bloomed by the gate (chat {idx})"
+                    ),
+                    "witness_you": 1,
+                    "witness_host": 1,
+                    "witness_guest": 0,
+                    "source": "direct",
+                    "reliability": 1.0,
+                    "significance": 1,
+                    "pinned": 0,
+                    "auto_pinned": 0,
+                },
+            )
+
+    # ---- GET /search?q=wisteria -> all 3 chats appear as result rows. ----
+    response = app_state_setup.get(f"/search?q={distinctive}")
+    assert response.status_code == 200
+    body = response.text
+
+    # Each chat_id appears in a result link href, e.g.
+    # ``href="/chats/chat_bot_a"``. The template renders one
+    # ``<a class="search-result-link" href="/chats/{chat_id}">`` per
+    # row, so a substring match per chat is sufficient.
+    for chat_id in chat_ids:
+        assert f'href="/chats/{chat_id}"' in body, (
+            f"chat {chat_id} missing from /search results: {body!r}"
+        )
+    # The owner display name (BotA) renders for each row — verify >= 3
+    # occurrences so we know all 3 result rows hydrated, not just 1.
+    assert body.count("BotA") >= 3
+
+    # ---- Sanity: distractor query yields no results. ----
+    distractor_response = app_state_setup.get(
+        "/search?q=nonexistentterm12345"
+    )
+    assert distractor_response.status_code == 200
+    distractor_body = distractor_response.text
+    # The "no matches" empty-state copy fires.
+    assert "No matches" in distractor_body
+    for chat_id in chat_ids:
+        assert f'href="/chats/{chat_id}"' not in distractor_body

tests/test_regenerate.py

@@ -757,6 +757,13 @@ def test_regenerate_with_prior_lifecycle_logs_warning(tmp_path, monkeypatch, cap
     # row's id.
     assert str(at_id) in msg
     assert str(completed_id) in msg
+    # T90.2: wording was tightened from "from superseded turn" to
+    # "at-or-after turn <id>" — when regenerating an OLDER turn, the
+    # listed transitions may include legitimate intervening-turn ones
+    # that stand on their own. The new phrasing avoids implying the
+    # warning's target turn directly authored every listed transition.
+    assert "at-or-after turn" in msg
+    assert "from superseded turn" not in msg
 
 
 def test_regenerate_sibling_lookup_scoped_to_chat(tmp_path, monkeypatch):

tests/test_search_ux.py

@@ -0,0 +1,135 @@
+"""T100 (Phase 4): cross-chat search UX (top-bar + results page).
+
+Verifies the FastAPI ``/search`` route that wraps T93's
+``search_all_memories`` service:
+
+* ``/search?q=...`` returns 200 + an HTML page that lists matches drawn
+  from MULTIPLE chats (not just the current one) and links each result
+  back to ``/chats/{chat_id}``.
+* ``/search`` with no query renders the page in its empty state with a
+  "enter a query" placeholder and no result rows (avoids hitting the
+  FTS index with an invalid empty MATCH).
+* Result links navigate to the originating chat so users can pick up
+  the thread where the memory came from.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+from fastapi.testclient import TestClient
+
+from chat.app import app
+from chat.db.connection import open_db
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+import chat.state.memory  # noqa: F401  (registers memory_written handler)
+
+
+@pytest.fixture
+def client(tmp_path, monkeypatch):
+    config_path = tmp_path / "config.toml"
+    config_path.write_text('featherless_api_key = "test"\n')
+    monkeypatch.setenv("CHAT_CONFIG_PATH", str(config_path))
+    monkeypatch.setenv("CHAT_DB_PATH", str(tmp_path / "test.db"))
+    with TestClient(app) as c:
+        yield c
+
+
+def _seed_two_chats_with_memories(db_path: Path) -> None:
+    """Seed: a ``you_entity``, two bots, two chats, and one ``rabbit``
+    memory per chat. Two-chat seeding lets the cross-chat assertion
+    actually distinguish "both chats appear" from "only the current
+    one does"."""
+    with open_db(db_path) as conn:
+        append_event(
+            conn,
+            kind="you_authored",
+            payload={"name": "Me", "pronouns": "", "persona": ""},
+        )
+        for bot_id, chat_id in (("bot_a", "chat_a"), ("bot_b", "chat_b")):
+            append_event(
+                conn,
+                kind="bot_authored",
+                payload={
+                    "id": bot_id,
+                    "name": bot_id.upper(),
+                    "persona": "thoughtful",
+                    "voice_samples": [],
+                    "traits": [],
+                    "backstory": "",
+                    "initial_relationship_to_you": "friend",
+                    "kickoff_prose": "kickoff",
+                },
+            )
+            append_event(
+                conn,
+                kind="chat_created",
+                payload={
+                    "id": chat_id,
+                    "host_bot_id": bot_id,
+                    "initial_time": "2026-04-26T20:00:00+00:00",
+                    "narrative_anchor": "Day 1",
+                    "weather": "",
+                },
+            )
+            append_event(
+                conn,
+                kind="memory_written",
+                payload={
+                    "owner_id": bot_id,
+                    "chat_id": chat_id,
+                    "pov_summary": f"the rabbit darted across {chat_id}",
+                    "witness_you": 1,
+                    "witness_host": 1,
+                    "witness_guest": 0,
+                    "source": "direct",
+                    "reliability": 1.0,
+                    "significance": 1,
+                    "pinned": 0,
+                    "auto_pinned": 0,
+                },
+            )
+        project(conn)
+
+
+def test_search_returns_results_from_multiple_chats(client, tmp_path):
+    """A single ``/search?q=rabbit`` must surface matches from BOTH
+    chats — the whole point of the cross-chat search box is that it
+    isn't owner-scoped."""
+    _seed_two_chats_with_memories(tmp_path / "test.db")
+    resp = client.get("/search?q=rabbit")
+    assert resp.status_code == 200
+    body = resp.text
+    # Both chats' memory snippets must appear in the rendered page.
+    assert "chat_a" in body
+    assert "chat_b" in body
+    assert "rabbit" in body.lower()
+
+
+def test_empty_query_renders_placeholder_not_results(client, tmp_path):
+    """``/search`` with no query renders the page in its empty state.
+
+    The placeholder copy is a contract with the user — they should see
+    "enter a query" rather than an empty result list that looks like a
+    no-match. Also: the FTS short-circuit means there are no result
+    rows to leak into the body."""
+    _seed_two_chats_with_memories(tmp_path / "test.db")
+    resp = client.get("/search")
+    assert resp.status_code == 200
+    body = resp.text.lower()
+    assert "enter a query" in body
+    # Seeded "rabbit" memories must NOT appear: empty query => no results.
+    assert "the rabbit darted" not in resp.text
+
+
+def test_result_links_navigate_to_chat(client, tmp_path):
+    """Each result links back to its originating chat so the user can
+    reopen the thread where the memory was first witnessed."""
+    _seed_two_chats_with_memories(tmp_path / "test.db")
+    resp = client.get("/search?q=rabbit")
+    assert resp.status_code == 200
+    # The link target is chat-level (memories don't carry an event_id
+    # column today, so we don't deep-link to a specific turn).
+    assert 'href="/chats/chat_a"' in resp.text

tests/test_snapshot_ux.py

@@ -0,0 +1,182 @@
+"""Tests for Task 99 — snapshot UX (manual trigger + list + restore + preview).
+
+Phase 4 surfaces the existing snapshot infrastructure (Phase 1 T20 / T31)
+through HTML routes so the user can:
+
+* see what snapshots exist,
+* take one on demand,
+* restore one with a hard confirm,
+* peek at metadata before restoring.
+
+The underlying service API lives in ``chat/services/snapshot.py`` and is
+already exercised by ``test_snapshot.py``; here we only verify the web
+surface wires the existing functions correctly.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+from fastapi.testclient import TestClient
+
+from chat.app import app
+from chat.db.connection import open_db
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+
+
+def _bot_payload(bot_id: str, name: str) -> dict:
+    return {
+        "id": bot_id,
+        "name": name,
+        "persona": "fancy",
+        "voice_samples": ["sample"],
+        "traits": ["shy"],
+        "backstory": "",
+        "initial_relationship_to_you": "coworker",
+        "kickoff_prose": "",
+    }
+
+
+@pytest.fixture
+def client(tmp_path, monkeypatch):
+    """A TestClient whose db + data_dir live under ``tmp_path``.
+
+    ``load_settings`` derives ``data_dir`` from ``CHAT_DB_PATH``'s parent
+    when ``CHAT_DATA_DIR`` is unset (see ``chat/config.py``), so this also
+    isolates the ``data/snapshots/`` tree to ``tmp_path``.
+    """
+    config_path = tmp_path / "config.toml"
+    config_path.write_text('featherless_api_key = "test"\n')
+    monkeypatch.setenv("CHAT_CONFIG_PATH", str(config_path))
+    monkeypatch.setenv("CHAT_DB_PATH", str(tmp_path / "test.db"))
+
+    with TestClient(app) as c:
+        c.tmp_path = tmp_path  # type: ignore[attr-defined]
+        yield c
+
+
+def _seed_bot(db_path: Path, bot_id: str = "bot_a", name: str = "BotA") -> None:
+    with open_db(db_path) as conn:
+        append_event(conn, kind="bot_authored", payload=_bot_payload(bot_id, name))
+        project(conn)
+
+
+def _take_snapshot_via_service(
+    db_path: Path, data_dir: Path, kind: str = "periodic"
+) -> Path:
+    from chat.services.snapshot import take_snapshot
+
+    with open_db(db_path) as conn:
+        return take_snapshot(conn, data_dir=data_dir, kind=kind)
+
+
+def test_list_snapshots_renders_page(client, tmp_path):
+    _seed_bot(tmp_path / "test.db", "bot_a", "BotA")
+    # Take two snapshots through the service so the listing has rows.
+    p1 = _take_snapshot_via_service(tmp_path / "test.db", tmp_path, kind="periodic")
+    p2 = _take_snapshot_via_service(tmp_path / "test.db", tmp_path, kind="rewind")
+
+    response = client.get("/snapshots")
+    assert response.status_code == 200
+    body = response.text
+    # Both filenames should appear in the listing.
+    assert p1.stem in body
+    assert p2.stem in body
+    # Both kinds should be visible.
+    assert "periodic" in body
+    assert "rewind" in body
+
+
+def test_take_snapshot_creates_new(client, tmp_path):
+    _seed_bot(tmp_path / "test.db", "bot_a", "BotA")
+    snapshot_dir = tmp_path / "snapshots" / "periodic"
+
+    before = (
+        len(list(snapshot_dir.glob("*.json"))) if snapshot_dir.exists() else 0
+    )
+    response = client.post("/snapshots/take", follow_redirects=False)
+    assert response.status_code == 303
+    assert response.headers["location"] == "/snapshots"
+
+    after = len(list(snapshot_dir.glob("*.json")))
+    assert after == before + 1
+
+
+def test_restore_snapshot_with_correct_confirm(client, tmp_path):
+    db_path = tmp_path / "test.db"
+    _seed_bot(db_path, "bot_a", "BotA")
+    snapshot_path = _take_snapshot_via_service(
+        db_path, tmp_path, kind="periodic"
+    )
+    snapshot_id = snapshot_path.stem  # filename without extension
+
+    # Mutate the DB after the snapshot was taken — restoring should erase
+    # the new bot.
+    with open_db(db_path) as conn:
+        append_event(
+            conn, kind="bot_authored", payload=_bot_payload("bot_b", "BotB")
+        )
+        project(conn)
+        bots_before = conn.execute(
+            "SELECT id FROM bots ORDER BY id"
+        ).fetchall()
+    assert {r[0] for r in bots_before} == {"bot_a", "bot_b"}
+
+    response = client.post(
+        f"/snapshots/restore/{snapshot_id}",
+        data={"confirm_id": snapshot_id, "kind": "periodic"},
+        follow_redirects=False,
+    )
+    assert response.status_code == 303
+
+    with open_db(db_path) as conn:
+        bots_after = conn.execute(
+            "SELECT id FROM bots ORDER BY id"
+        ).fetchall()
+    # The post-snapshot bot should be gone.
+    assert {r[0] for r in bots_after} == {"bot_a"}
+
+
+def test_restore_snapshot_wrong_confirm_400(client, tmp_path):
+    db_path = tmp_path / "test.db"
+    _seed_bot(db_path, "bot_a", "BotA")
+    snapshot_path = _take_snapshot_via_service(
+        db_path, tmp_path, kind="periodic"
+    )
+    snapshot_id = snapshot_path.stem
+
+    response = client.post(
+        f"/snapshots/restore/{snapshot_id}",
+        data={"confirm_id": "not_the_right_id", "kind": "periodic"},
+        follow_redirects=False,
+    )
+    assert response.status_code == 400
+
+
+def test_preview_renders_metadata(client, tmp_path):
+    db_path = tmp_path / "test.db"
+    _seed_bot(db_path, "bot_a", "BotA")
+    snapshot_path = _take_snapshot_via_service(
+        db_path, tmp_path, kind="periodic"
+    )
+    snapshot_id = snapshot_path.stem
+
+    # Append more events post-snapshot so the delta is non-zero.
+    with open_db(db_path) as conn:
+        append_event(
+            conn, kind="bot_authored", payload=_bot_payload("bot_b", "BotB")
+        )
+        project(conn)
+
+    response = client.get(
+        f"/snapshots/{snapshot_id}/preview", params={"kind": "periodic"}
+    )
+    assert response.status_code == 200
+    body = response.text
+    assert snapshot_id in body
+    # Snapshot's last_event_id and current event_log size should appear.
+    dump = json.loads(snapshot_path.read_text())
+    assert str(dump["last_event_id"]) in body

tests/test_turn_common.py

@@ -186,6 +186,82 @@ def test_read_recent_dialogue_filters_superseded_and_other_chats(tmp_path):
     assert ut_id is not None
 
 
+def test_read_recent_dialogue_limit_respects_chat_scope(tmp_path):
+    """T90.1: ``read_recent_dialogue`` must push the chat_id filter into
+    SQL so that ``LIMIT N`` returns N rows scoped to the requested chat —
+    not N globally-recent rows that may then be filtered down to fewer in
+    Python.
+
+    Setup: two chats with 60 turns each, interleaved. With the old
+    post-fetch filter, ``LIMIT 50`` would pull 50 globally-recent rows
+    (most or all from chat_b — the most recent inserts) and then drop
+    chat_b ones via the Python check, yielding far fewer than 50 chat_a
+    rows. After the SQL pushdown, ``LIMIT 50`` should return exactly 50
+    chat_a rows.
+    """
+    db = tmp_path / "test.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        for chat_id, host_bot in (("chat_a", "bot_a"), ("chat_b", "bot_b")):
+            append_event(
+                conn,
+                kind="bot_authored",
+                payload={
+                    "id": host_bot,
+                    "name": host_bot,
+                    "persona": "...",
+                    "voice_samples": [],
+                    "traits": [],
+                    "backstory": "",
+                    "initial_relationship_to_you": "",
+                    "kickoff_prose": "",
+                },
+            )
+            append_event(
+                conn,
+                kind="chat_created",
+                payload={
+                    "id": chat_id,
+                    "host_bot_id": host_bot,
+                    "initial_time": "2026-04-26T20:00:00+00:00",
+                    "narrative_anchor": "Day 1",
+                    "weather": "",
+                },
+            )
+        # Interleave 60 user_turn rows in each chat — chat_b's go in last
+        # so they dominate the global tail.
+        for i in range(60):
+            append_event(
+                conn,
+                kind="user_turn",
+                payload={
+                    "chat_id": "chat_a",
+                    "prose": f"a-{i}",
+                    "segments": [],
+                },
+            )
+        for i in range(60):
+            append_event(
+                conn,
+                kind="user_turn",
+                payload={
+                    "chat_id": "chat_b",
+                    "prose": f"b-{i}",
+                    "segments": [],
+                },
+            )
+        project(conn)
+
+        out = read_recent_dialogue(conn, "chat_a", limit=50)
+
+    # All returned rows should belong to chat_a (texts a-* only).
+    assert len(out) == 50
+    for entry in out:
+        assert entry["text"].startswith("a-"), (
+            f"foreign chat row leaked: {entry!r}"
+        )
+
+
 def test_gather_prior_edges_fills_missing_with_default(tmp_path):
     """``gather_prior_edges`` returns one entry per directed pair across
     ``present_ids``. Missing rows fall back to the schema default

tests/test_vector_search.py

@@ -0,0 +1,242 @@
+from __future__ import annotations
+
+import pytest
+
+from chat.db.connection import open_db
+from chat.db.migrate import apply_migrations
+from chat.eventlog.log import append_event
+from chat.eventlog.projector import project
+import chat.state.memory  # registers memory_written handler
+import chat.state.embeddings  # registers embedding handlers
+from chat.services.vector_search import vector_search
+
+
+def _base_memory(**overrides):
+    payload = {
+        "owner_id": "bot_a",
+        "chat_id": "chat_bot_a",
+        "scene_id": 1,
+        "pov_summary": "She laughed at his joke about owls.",
+        "witness_you": 1,
+        "witness_host": 1,
+        "witness_guest": 0,
+        "chat_clock_at": "2026-04-26T10:00:00",
+        "source": "direct",
+        "reliability": 1.0,
+        "significance": 1,
+        "pinned": 0,
+        "auto_pinned": 0,
+    }
+    payload.update(overrides)
+    return payload
+
+
+def _one_hot(dim: int, idx: int) -> list[float]:
+    """Return a one-hot vector of length ``dim`` with 1.0 at ``idx``."""
+    v = [0.0] * dim
+    v[idx] = 1.0
+    return v
+
+
+def _seed_memory_with_embedding(
+    conn,
+    *,
+    owner_id: str,
+    pov_summary: str,
+    vector: list[float],
+    significance: int = 1,
+    witness_you: int = 1,
+    witness_host: int = 1,
+    witness_guest: int = 0,
+    model: str = "test-model",
+) -> int:
+    append_event(
+        conn,
+        kind="memory_written",
+        payload=_base_memory(
+            owner_id=owner_id,
+            pov_summary=pov_summary,
+            significance=significance,
+            witness_you=witness_you,
+            witness_host=witness_host,
+            witness_guest=witness_guest,
+        ),
+    )
+    project(conn)
+    memory_id = conn.execute(
+        "SELECT id FROM memories WHERE pov_summary = ?", (pov_summary,)
+    ).fetchone()[0]
+    append_event(
+        conn,
+        kind="embedding_indexed",
+        payload={
+            "memory_id": memory_id,
+            "vector": vector,
+            "model": model,
+            "dim": len(vector),
+        },
+    )
+    project(conn)
+    return memory_id
+
+
+def test_vector_search_returns_nearest_neighbors(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        dim = 8
+        ids = []
+        for i in range(5):
+            mid = _seed_memory_with_embedding(
+                conn,
+                owner_id="bot_a",
+                pov_summary=f"Memory {i}.",
+                vector=_one_hot(dim, i),
+            )
+            ids.append(mid)
+
+        # Query close to memory index 3 (one-hot at position 3, plus tiny noise).
+        query = _one_hot(dim, 3)
+        query[2] = 0.01
+
+        results = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="you",
+            query_vector=query,
+            k=3,
+        )
+        assert len(results) == 3
+        # Top-1 must be memory at index 3.
+        assert results[0]["memory_id"] == ids[3]
+        assert results[0]["pov_summary"] == "Memory 3."
+        # Score for the near-perfect match should be very close to 1.0.
+        assert results[0]["score"] > 0.99
+        # Results sorted by score DESC.
+        scores = [r["score"] for r in results]
+        assert scores == sorted(scores, reverse=True)
+        # Second place should be memory index 2 (the small noise component).
+        assert results[1]["memory_id"] == ids[2]
+
+
+def test_vector_search_respects_witness_filter(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        dim = 4
+        # Memory visible to you=1, host=1, guest=0.
+        _seed_memory_with_embedding(
+            conn,
+            owner_id="bot_a",
+            pov_summary="Restricted.",
+            vector=_one_hot(dim, 0),
+            witness_you=1,
+            witness_host=1,
+            witness_guest=0,
+        )
+
+        # Guest sees nothing.
+        guest_results = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="guest",
+            query_vector=_one_hot(dim, 0),
+            k=4,
+        )
+        assert guest_results == []
+
+        # Host sees the memory.
+        host_results = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="host",
+            query_vector=_one_hot(dim, 0),
+            k=4,
+        )
+        assert len(host_results) == 1
+        assert host_results[0]["pov_summary"] == "Restricted."
+
+        # You also see it.
+        you_results = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="you",
+            query_vector=_one_hot(dim, 0),
+            k=4,
+        )
+        assert len(you_results) == 1
+
+
+def test_vector_search_respects_owner_filter(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        dim = 4
+        _seed_memory_with_embedding(
+            conn,
+            owner_id="bot_a",
+            pov_summary="Owner A memory.",
+            vector=_one_hot(dim, 0),
+        )
+        _seed_memory_with_embedding(
+            conn,
+            owner_id="bot_b",
+            pov_summary="Owner B memory.",
+            vector=_one_hot(dim, 0),
+        )
+
+        a_results = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="you",
+            query_vector=_one_hot(dim, 0),
+            k=10,
+        )
+        assert len(a_results) == 1
+        assert a_results[0]["pov_summary"] == "Owner A memory."
+
+        b_results = vector_search(
+            conn,
+            owner_id="bot_b",
+            witness_role="you",
+            query_vector=_one_hot(dim, 0),
+            k=10,
+        )
+        assert len(b_results) == 1
+        assert b_results[0]["pov_summary"] == "Owner B memory."
+
+
+def test_vector_search_invalid_witness_role_raises(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        with pytest.raises(ValueError, match="witness_role"):
+            vector_search(
+                conn,
+                owner_id="bot_a",
+                witness_role="invalid",
+                query_vector=[1.0, 0.0, 0.0],
+                k=4,
+            )
+
+
+def test_vector_search_empty_when_no_embeddings_indexed(tmp_path):
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        # Seed a memory but don't index an embedding for it.
+        append_event(
+            conn,
+            kind="memory_written",
+            payload=_base_memory(owner_id="bot_a", pov_summary="No embedding here."),
+        )
+        project(conn)
+
+        results = vector_search(
+            conn,
+            owner_id="bot_a",
+            witness_role="you",
+            query_vector=[1.0, 0.0, 0.0, 0.0],
+            k=4,
+        )
+        assert results == []

tests/test_world.py

@@ -324,11 +324,11 @@ def test_get_scene_returns_none_for_missing(tmp_path):
         assert active_scene(conn, "chat_missing") is None
 
 
-def test_schema_version_after_migration_is_11(tmp_path):
+def test_schema_version_after_migration_is_13(tmp_path):
     db = tmp_path / "t.db"
     apply_migrations(db)
     with open_db(db) as conn:
         row = conn.execute(
             "SELECT value FROM meta WHERE key = 'schema_version'"
         ).fetchone()
-        assert int(row[0]) == 11
+        assert int(row[0]) == 13