correlator: address #116 review — call talkgroup id in the prompt, sort candidates

drb-correlation-review: ship, with two bounds the low-bar link rule needs.

1. _call_block emitted only the talkgroup NAME while _inc_summary emits
   numeric tg ids, so the "same talkgroup" precondition in _RULES was
   unevaluable and the low link bar applied unconditionally. _call_block now
   prints "Talkgroup: <name> (id <n>)".
2. ctx["recent"] is an unordered Firestore slice with no order_by; a busy 2h
   window (~40 active incidents) showed the model an arbitrary half of the
   candidates. _prompt_incidents() sorts by updated_at desc before the [:20]
   cap — also makes each row's idle: field monotonic.

+2 tests. Full c2-core suite green (sandboxed venv).

Review follow-ups (not blockers): _parse_response demotes an unresolvable
link to orphan (drops the call) rather than falling back to rules — now on
rising link volume; the 45% tiebreak escalation rate / smart-model cost is
untouched; _ROAD_RE swallows leading tokens so "10 Parker Street" still
won't road-overlap "Parker St".

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

drb-c2-core/app/internal/llm_correlator.py

@@ -91,11 +91,29 @@ def _call_block(ctx: dict) -> str:
         lines.append(f"Units: {ctx['call_units']}")
     if ctx["call_vehicles"]:
         lines.append(f"Vehicles: {ctx['call_vehicles']}")
-    if ctx["talkgroup_name"]:
-        lines.append(f"Talkgroup: {ctx['talkgroup_name']}")
+    if ctx["talkgroup_name"] or ctx.get("talkgroup_id") is not None:
+        # Both the name and the id — _inc_summary emits numeric tg ids, so the
+        # id is what makes the "same talkgroup" rule in _RULES evaluable
+        # (server-26#115 review).
+        tgid = ctx.get("talkgroup_id")
+        name = ctx["talkgroup_name"] or "?"
+        lines.append(f"Talkgroup: {name}" + (f" (id {tgid})" if tgid is not None else ""))
     return "\n".join(lines) if lines else "(no details)"
 
 
+def _prompt_incidents(recent: list[dict]) -> list[dict]:
+    """The ≤20 candidates shown to the model, most-recently-active first.
+
+    `ctx["recent"]` is an unordered slice of a Firestore result with no
+    order_by, so a busy 2h window (~40 active incidents) meant the model saw
+    an arbitrary half of the candidates (server-26#115 review). Sorting by
+    updated_at desc also makes each row's `idle:` field monotonic.
+    """
+    def _key(inc: dict):
+        return str(inc.get("updated_at") or inc.get("started_at") or "")
+    return sorted(recent, key=_key, reverse=True)[:20]
+
+
 _SCHEMA = '{"action": "link" | "new" | "orphan", "incident_id": "<id_string or null>", "reasoning": "<one sentence>"}'
 
 _RULES = """
@@ -125,7 +143,7 @@ def _build_decide_prompt(ctx: dict) -> str:
     now    = ctx["now"]
     recent = ctx["recent"]
     inc_block = (
-        "\n".join(_inc_summary(inc, now) for inc in recent[:20])
+        "\n".join(_inc_summary(inc, now) for inc in _prompt_incidents(recent))
         if recent else "(none)"
     )
     return (
@@ -143,7 +161,7 @@ def _build_tiebreak_prompt(rules_decision: dict, llm_decision: dict, ctx: dict)
     now    = ctx["now"]
     recent = ctx["recent"]
     inc_block = (
-        "\n".join(_inc_summary(inc, now) for inc in recent[:20])
+        "\n".join(_inc_summary(inc, now) for inc in _prompt_incidents(recent))
         if recent else "(none)"
     )
 

drb-c2-core/tests/test_correlator_115.py

@@ -14,7 +14,7 @@ from datetime import datetime, timezone
 from app.internal.incident_correlator import (
     _extract_road_ids, _location_mentions_road_overlap,
 )
-from app.internal.llm_correlator import _inc_summary
+from app.internal.llm_correlator import _inc_summary, _prompt_incidents
 
 NOW = datetime(2026, 9, 7, 8, 0, 0, tzinfo=timezone.utc)
 
@@ -52,3 +52,16 @@ def test_inc_summary_omits_missing_optional_fields():
     s = _inc_summary({"incident_id": "x", "updated_at": NOW.isoformat()}, NOW)
     assert "title:" not in s and "tg:" not in s and "loc:" not in s
     assert s.startswith("id:x")
+
+
+def test_prompt_incidents_is_most_recently_active_first_and_capped():
+    recent = [
+        {"incident_id": f"i{n}", "updated_at": f"2026-09-07T0{n}:00:00+00:00"}
+        for n in range(1, 8)
+    ]
+    ordered = _prompt_incidents(recent)
+    assert [i["incident_id"] for i in ordered] == ["i7", "i6", "i5", "i4", "i3", "i2", "i1"]
+    assert len(_prompt_incidents(recent * 5)) == 20
+    # falls back to started_at when updated_at is absent, and never raises
+    assert _prompt_incidents([{"incident_id": "a", "started_at": NOW.isoformat()},
+                              {"incident_id": "b"}])[0]["incident_id"] == "a"