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