A unit call-sign is not a place

"Post 1-2" reached the geocoder, resolved against its talkgroup anchor and
produced a confident pin in the right town for an event with no known
location — while sitting in the same incident's `units` list the whole time.
A plausible wrong pin is worse than no pin: nothing downstream can tell it
is wrong.

Extraction returns `location` and `units` from one pass, so a string in both
is a misclassification, not two facts. Drop it before the geocoder sees it.

Closes server-26#52.

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

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

@@ -282,6 +282,27 @@ def clean_location(value) -> Optional[str]:
     return s
 
 
+def location_is_unit(location, units) -> bool:
+    """
+    True when a location label is really one of the incident's own unit
+    call-signs.
+
+    Extraction returns `location` and `units` from the same pass, so a string
+    appearing in both is a misclassification, not two facts. "Post 1-2" reached
+    the geocoder that way, resolved against its talkgroup anchor, and produced a
+    confident pin in the right town for an event that has no known location at
+    all — worse than no pin, because nothing downstream can tell it is wrong.
+    See server-26#52.
+
+    Public because `intelligence.py` applies it at extraction time, alongside
+    `clean_location`, so the string never reaches the geocoder.
+    """
+    key = _place_key(location)
+    if not key:
+        return False
+    return any(key == _place_key(u) for u in (units or []))
+
+
 def _place_key(value) -> str:
     """Case- and punctuation-blind key for comparing two location labels."""
     return re.sub(r"[^a-z0-9]+", " ", str(value or "").lower()).strip()

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

@@ -19,7 +19,7 @@ from app.internal import area_context
 # Location validity is defined once, by the module that owns the incident's
 # location/pin invariant.  incident_correlator does not import this module, so
 # this is not a cycle.
-from app.internal.incident_correlator import clean_location
+from app.internal.incident_correlator import clean_location, location_is_unit
 
 _PROMPT_TEMPLATE = """You are analyzing a P25 public safety radio recording. The audio was transcribed by Whisper through a digital radio vocoder, which introduces errors. Each numbered transmission is a separate PTT press from a different radio.
 
@@ -252,6 +252,18 @@ async def extract_scenes(
         location:           Optional[str]  = clean_location(scene.get("location"))
         vehicles:           list[str]      = scene.get("vehicles") or []
         units:              list[str]      = scene.get("units") or []
+        # A "location" that is also one of this scene's own units is a unit
+        # call-sign, not a place. Both lists come from the same extraction pass,
+        # so the disagreement is free to detect and the string must be dropped
+        # before it reaches the geocoder — anchored place verification will
+        # otherwise resolve "Post 1-2" to a confident, plausible, wrong pin in
+        # the right town. See server-26#52.
+        if location and location_is_unit(location, units):
+            logger.info(
+                f"Intelligence: dropping location {location!r} — it is one of "
+                f"this scene's units, not a place"
+            )
+            location = None
         cleared_units:      list[str]      = scene.get("cleared_units") or []
         # Every call carries a severity — it is the signal the correlator uses to
         # decide whether a call is incident-worthy at all, so it must never be

drb-c2-core/tests/test_incident_identity.py

@@ -28,7 +28,7 @@ from unittest.mock import AsyncMock, patch
 
 from app.internal.incident_correlator import (
     _build_context, _create_incident, _update_incident,
-    _resolve_location_pair, _verified_pin, clean_location,
+    _resolve_location_pair, _verified_pin, clean_location, location_is_unit,
 )
 
 NOW = datetime(2026, 8, 20, 7, 25, 0, tzinfo=timezone.utc)
@@ -340,3 +340,35 @@ async def test_a_legacy_incidents_title_is_not_claimed_by_the_next_call():
                           incident_type="police", severity="routine")
     assert "title" not in updates
     assert updates["location"] == "80 Grasslands Road"
+
+
+# ── server-26#52: a unit call-sign must never become a map pin ────────────────
+#
+# "Post 1-2" passed clean_location (it has a word in it), geocoded against the
+# Ossining anchor and produced a confident pin in the right town for an event
+# with no known location. It was in the same incident's `units` all along.
+
+@pytest.mark.parametrize("location,units", [
+    ("Post 1-2", ["1-2", "Lincoln", "Post 1-2"]),   # the dump's actual incident
+    ("post 1-2", ["Post 1-2"]),                     # case-blind
+    ("Post 1-2.", ["Post 1-2"]),                    # punctuation-blind
+    ("Engine 4", ["Engine 4", "Ladder 1"]),
+])
+def test_location_matching_a_unit_is_rejected(location, units):
+    assert location_is_unit(location, units) is True
+
+
+@pytest.mark.parametrize("location,units", [
+    ("Water Street", ["1-2", "Post 1-2"]),          # a real place, same incident
+    ("South High", []),                             # no units extracted
+    ("Riverdale Station", ["Lincoln"]),
+    ("", ["Post 1-2"]),                             # nothing to compare
+    (None, ["Post 1-2"]),
+])
+def test_real_places_survive_the_unit_check(location, units):
+    assert location_is_unit(location, units) is False
+
+
+def test_unit_check_does_not_match_on_substrings():
+    """`1-2` is a unit; "1-2 Main Street" is an address that contains it."""
+    assert location_is_unit("1-2 Main Street", ["1-2"]) is False