feat: LLM-merged group meta-summary (T70)

chat/services/scene_summarize.py

@@ -334,26 +334,92 @@ async def apply_scene_close_summary(
             timeout_s=timeout_s,
         )
 
-    # Group node update: naive per-POV concat for v2. Only fires when
-    # both POVs ran (i.e. the guest is present) and a group_node row
-    # exists for this chat.
+    # Group node update: T70 runs a third classifier call to merge the
+    # two per-POV summaries into a coherent group-level view + a brief
+    # group-dynamic note. Falls back to the Phase 2 naive concat on
+    # classifier failure (see :func:`merge_group_summary`). Only fires
+    # when both POVs ran (i.e. the guest is present) and a group_node
+    # row exists for this chat.
     if guest_pov is not None and get_group_node(conn, chat_id) is not None:
         host_bot = get_bot(conn, host_bot_id) or {"name": host_bot_id}
         guest_bot = get_bot(conn, guest_bot_id) or {"name": guest_bot_id}
         host_name = host_bot.get("name", host_bot_id) or host_bot_id
         guest_name = guest_bot.get("name", guest_bot_id) or guest_bot_id
-        group_summary = (
-            f"{host_name}: {host_pov.summary}\n\n"
-            f"{guest_name}: {guest_pov.summary}"
+        merged = await merge_group_summary(
+            client,
+            classifier_model=classifier_model,
+            host_name=host_name,
+            host_pov_summary=host_pov.summary,
+            guest_name=guest_name,
+            guest_pov_summary=guest_pov.summary,
+            timeout_s=timeout_s,
         )
         append_and_apply(
             conn,
             kind="group_node_updated",
             payload={
                 "chat_id": chat_id,
-                "summary": group_summary,
-                "dynamic": "",
+                "summary": merged.summary,
+                "dynamic": merged.dynamic,
             },
         )
 
     return host_pov
+
+
+class GroupMetaSummary(BaseModel):
+    """Classifier output: a merged group-level view of a closed scene.
+
+    Defaults are an empty no-op so callers can use the schema's default
+    as a sentinel; in practice :func:`merge_group_summary` builds an
+    explicit naive-concat fallback rather than returning these defaults
+    directly so existing Phase 2 behavior is preserved on classifier
+    failure.
+    """
+
+    summary: str = ""
+    dynamic: str = ""
+
+
+_GROUP_MERGE_SYSTEM = (
+    "Given two per-POV scene summaries from a 3-entity scene (you + "
+    "host + guest), produce a coherent group-level summary capturing "
+    "the shared events as both witnesses experienced them, plus a "
+    "brief 'dynamic' note describing the trio's group dynamic during "
+    "the scene. Output strict JSON matching schema."
+)
+
+
+async def merge_group_summary(
+    client: LLMClient,
+    *,
+    classifier_model: str,
+    host_name: str,
+    host_pov_summary: str,
+    guest_name: str,
+    guest_pov_summary: str,
+    timeout_s: float = 30.0,
+) -> GroupMetaSummary:
+    """Merge two per-POV scene summaries into a coherent group-level
+    summary + group-dynamic note. Falls back to the naive concat (the
+    existing behavior) on classifier failure."""
+    user = (
+        f"{host_name} (host) POV summary:\n{host_pov_summary}\n\n"
+        f"{guest_name} (guest) POV summary:\n{guest_pov_summary}"
+    )
+    fallback = GroupMetaSummary(
+        summary=(
+            f"{host_name}: {host_pov_summary}\n\n"
+            f"{guest_name}: {guest_pov_summary}"
+        ),
+        dynamic="",
+    )
+    return await classify(
+        client,
+        model=classifier_model,
+        system=_GROUP_MERGE_SYSTEM,
+        user=user,
+        schema=GroupMetaSummary,
+        default=fallback,
+        timeout_s=timeout_s,
+    )