Merge pull request 'correlator: gate LLM-orphan against rules-new instead of escalating to tiebreak (#115)' (#125) from fix/115-consensus-orphan-gate into main

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

@@ -91,6 +91,13 @@ def _max_severity(current: Optional[str], new: Optional[str]) -> str:
 _MAX_PURSUIT_SPEED_KM_PER_MIN = 8.0   # ~300 km/h, intentionally generous
 _PURSUIT_PROXIMITY_KM         = 20.0  # expanded radius for moving incidents
 
+# server-26#115 — the location path linked on `location_proximity_km` (0.5 km)
+# alone, with no unit or content check. In a dense village two unrelated events
+# routinely geocode that close (a vehicle lockout stitched to a station-restroom
+# slip; two different churches an hour apart). A location link now needs unit
+# overlap with the candidate OR a distance under this tighter bar.
+_LOCATION_TIGHT_PROXIMITY_KM  = 0.2
+
 _DISPATCH_TG_RE = re.compile(
     r"\bdispatch\b|\bdisp\b"
     r"|\bpatched\b"   # patched channels aggregate multiple call streams
@@ -239,6 +246,22 @@ def _matching_units(call_units: Optional[list[str]], inc_units: Optional[list[st
     return [u for u in (call_units or []) if _normalize_unit(u) in inc_keys]
 
 
+def has_event_substance(ctx: dict) -> bool:
+    """
+    True when the call carries content beyond who-was-speaking-and-where:
+    a vehicle, a geocode, or a tag.
+
+    This is the substance half of the incident-creation gate (see
+    `_run_decision`, "Severity, not type, decides..."), factored out so the
+    consensus LLM-orphan gate in routers/upload.py mirrors it exactly and can
+    never drop a call the creation gate would have opened. `call_units` and
+    `location` are deliberately excluded — radio protocol puts a unit ID and a
+    place name in almost every transmission, so counting them as substance
+    makes the check trivially true.
+    """
+    return bool(ctx.get("call_vehicles") or ctx.get("coords") or ctx.get("tags"))
+
+
 def _infer_type_from_tags(tags: list[str]) -> Optional[str]:
     """Return an incident type inferred from tags, or None if ambiguous."""
     for tag in tags:
@@ -1173,6 +1196,10 @@ def _run_decision(ctx: dict) -> dict:
 
     # ── 2. Location path: proximity match (time-limited, cross-type) ─────────
     if not matched_incident and coords:
+        # server-26#115 — score every in-radius candidate and link the NEAREST
+        # that carries corroboration, rather than whichever incident happened to
+        # come first in an unsorted `recent`.
+        loc_candidates: list[tuple] = []
         for inc in recent:
             inc_coords = inc.get("location_coords")
             if not inc_coords:
@@ -1189,18 +1216,49 @@ def _run_decision(ctx: dict) -> dict:
                 elapsed_min = max(_incident_idle_minutes(inc, now), 0.1)
                 if (dist_km / elapsed_min) > _MAX_PURSUIT_SPEED_KM_PER_MIN:
                     continue  # implausible speed — skip this candidate
-            if dist_km <= radius:
+            if dist_km > radius:
+                continue
+            # server-26#115 — a bare sub-radius distance is not enough on its
+            # own. Require corroboration: unit overlap with the candidate, OR
+            # a much tighter proximity. Pursuit incidents keep their
+            # movement-speed-validated wide radius (they passed the speed
+            # check above), so they are exempt.
+            unit_overlap = bool(
+                _unit_keys(call_units) & _unit_keys(inc.get("units"))
+            )
+            tight_proximity = dist_km <= _LOCATION_TIGHT_PROXIMITY_KM
+            if not (is_pursuit_inc or unit_overlap or tight_proximity):
+                logger.info(
+                    f"Correlator location-path skipped: call {call_id} vs "
+                    f"{inc['incident_id']} — dist={dist_km:.2f}km within radius "
+                    f"but no unit overlap and not tight-proximity "
+                    f"(<= {_LOCATION_TIGHT_PROXIMITY_KM}km)"
+                )
+                continue
+            loc_candidates.append((dist_km, unit_overlap, is_pursuit_inc, inc))
+
+        if loc_candidates:
+            loc_candidates.sort(key=lambda c: c[0])
+            dist_km, unit_overlap, is_pursuit_inc, inc = loc_candidates[0]
             matched_incident = inc
+            # Distinct from the fast path's "unit_overlap" so the admin
+            # corr_fit_signal histogram (routers/admin.py) does not merge a
+            # location-path link into the fast-path bucket (#35).
+            fit_signal = "location_unit_overlap" if unit_overlap else "location_proximity"
             corr_debug = {
                 "corr_path": "location",
                 "corr_distance_km": round(dist_km, 3),
                 "corr_pursuit_mode": is_pursuit_inc,
+                "corr_fit_signal": fit_signal,
             }
+            if unit_overlap and call_units:
+                corr_debug["corr_matched_units"] = _matching_units(
+                    call_units, inc.get("units")
+                )
             logger.info(
                 f"Correlator location-path: call {call_id} → {inc['incident_id']} "
-                    f"(dist={dist_km:.2f}km, pursuit={is_pursuit_inc})"
+                f"(dist={dist_km:.2f}km, pursuit={is_pursuit_inc}, signal={fit_signal})"
             )
-                break
 
     # ── 2.5. Cross-TG path: same department, overlapping units, moderate similarity ──
     #
@@ -1337,7 +1395,7 @@ def _run_decision(ctx: dict) -> dict:
     # each.  A vehicle, a geocode, or a tag means the extractor found something
     # beyond who was speaking and where they stood.
     if not resolved_type:
-        has_substance = bool(call_vehicles or coords or tags)
+        has_substance = has_event_substance(ctx)
         if call_severity in ("minor", "moderate", "major") or has_substance:
             resolved_type = "other"
             logger.info(

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

@@ -20,6 +20,22 @@ from app.internal.logger import logger
 from app.internal import firestore as fstore
 from app.config import settings
 
+# Standard link-only retry budget before a call is tombstoned corr_path="unlinked".
+MAX_SWEEP_ATTEMPTS = 3
+# server-26#115 — a call the consensus LLM-orphan gate parked (llm=orphan vs
+# rules=new, no substance) gets a longer budget. The gate fires before any
+# incident for the job may exist, so the substantive call that would justify
+# linking can land well after the standard ~6 min. Still link-only: a genuinely
+# thin call must not mint an incident, and the rules creation gate would re-orphan
+# it anyway.
+GATED_ORPHAN_SWEEP_ATTEMPTS = 10
+
+
+def _max_sweep_attempts(call: dict) -> int:
+    if call.get("corr_consensus") == "llm_orphan_gate":
+        return GATED_ORPHAN_SWEEP_ATTEMPTS
+    return MAX_SWEEP_ATTEMPTS
+
 
 async def recorrelation_loop() -> None:
     interval = settings.summary_interval_minutes * 60
@@ -46,10 +62,9 @@ async def _run_sweep_pass() -> None:
         ("status",   "==",  "ended"),
         ("ended_at", ">=",  cutoff),
     ])
-    # corr_path="unlinked" is written after MAX_SWEEP_ATTEMPTS failures.
+    # corr_path="unlinked" is written after the attempt budget is exhausted.
     # Allows a few retries so a welfare-check call can link to an escalation
     # incident that is created a few minutes later, without sweeping 30× forever.
-    MAX_SWEEP_ATTEMPTS = 3
     orphans = [
         c for c in recent_ended
         if not c.get("incident_ids") and not c.get("incident_id")
@@ -61,7 +76,7 @@ async def _run_sweep_pass() -> None:
         # the thin path minutes later and attached to whatever was most recent —
         # a second route into the over-merge the thin fix above addresses.
         and not c.get("skip_reason")
-        and c.get("corr_sweep_count", 0) < MAX_SWEEP_ATTEMPTS
+        and c.get("corr_sweep_count", 0) < _max_sweep_attempts(c)
     ]
 
     if not orphans:
@@ -120,12 +135,12 @@ async def _recorrelate_orphan(call: dict) -> bool:
         )
         return True
 
-    # Increment the attempt counter. Once MAX_SWEEP_ATTEMPTS is reached the
-    # orphan filter above will stop picking this call up, and we write
-    # corr_path="unlinked" as a permanent tombstone.
+    # Increment the attempt counter. Once the budget is reached the orphan filter
+    # above will stop picking this call up, and we write corr_path="unlinked" as
+    # a permanent tombstone.
     attempts = call.get("corr_sweep_count", 0) + 1
     update: dict = {"corr_sweep_count": attempts}
-    if attempts >= 3:
+    if attempts >= _max_sweep_attempts(call):
         update["corr_path"] = "unlinked"
     await fstore.doc_set("calls", call_id, update)
     return False

drb-c2-core/app/routers/upload.py

@@ -100,6 +100,64 @@ async def upload_call_audio(
     return {"url": gcs_uri}
 
 
+# server-26#115 — the consensus LLM-orphan gate only fires when the call is
+# genuinely substanceless. The earlier version tested `rules_decision["corr_debug"]`
+# for a "positive signal", but corr_debug is EMPTY at preview time for
+# action=="new" (corr_path:"new" is written at APPLY time), so that test was
+# always False and the gate dropped real events — a major "extinguishing fire",
+# geocoded calls, pursuit updates. The substance test now runs against `ctx`,
+# which is fully populated at preview time.
+
+
+def _recent_incident_on_same_talkgroup(ctx: dict) -> bool:
+    """
+    True when one of the already-loaded recent incidents is running on this
+    call's own system + talkgroup. Covers the "unit dispatched on the dispatch
+    channel, thin acknowledgement 10-30s later" case: the ack carries no
+    substance of its own but plainly belongs to the job just opened.
+
+    Reads ctx["recent"] — the same window-filtered candidate list the rules
+    engine already loaded — so this adds no Firestore read.
+    """
+    tg_id = ctx.get("talkgroup_id")
+    system_id = ctx.get("system_id")
+    if tg_id is None or not system_id:
+        return False
+    tg_str = str(tg_id)
+    for inc in ctx.get("recent") or []:
+        if system_id in (inc.get("system_ids") or []) and tg_str in (inc.get("talkgroup_ids") or []):
+            return True
+    return False
+
+
+def _call_is_substanceless(ctx: dict) -> bool:
+    """
+    True when the call carries nothing that marks it as a real event:
+      • severity is not moderate/major, AND
+      • no vehicle, geocode or tag (incident_correlator.has_event_substance —
+        the same predicate the incident-creation gate uses), AND
+      • no recent incident already running on the same talkgroup.
+    Only then may the LLM-orphan gate drop the call without a tiebreak.
+    """
+    from app.internal import incident_correlator
+
+    # The incident-creation gate skips the has_event_substance check entirely
+    # when a type resolved (incident_correlator._run_decision ~:1397), so a
+    # typed call — fire/medical/etc. — opens an incident on substance we do not
+    # re-check here. reassignment=True is dispatch pulling a unit onto a NEW
+    # job (units are blanked at :296 for exactly that reason): the strongest
+    # new-incident signal in the pipeline. Either one means "keep the tiebreak".
+    if ctx.get("incident_type") or ctx.get("reassignment"):
+        return False
+    if (ctx.get("call_severity") or "routine") in ("moderate", "major"):
+        return False
+    if incident_correlator.has_event_substance(ctx):
+        return False
+    if _recent_incident_on_same_talkgroup(ctx):
+        return False
+    return True
+
+
 async def _correlate_with_consensus(
     call_id: str,
     node_id: str,
@@ -151,6 +209,39 @@ async def _correlate_with_consensus(
         rules_decision["corr_debug"]["corr_llm_reasoning"] = llm_decision.get("reasoning", "")
         return await incident_correlator.apply_correlation(preview)
 
+    # server-26#115 — LLM-orphan gate.
+    # When the cheap LLM says `orphan`, the rules engine says `new`, and the call
+    # is genuinely substanceless (routine severity, no vehicle/geocode/tag, and
+    # no incident already running on this talkgroup), resolve to `orphan` and DO
+    # NOT pay for the smart tiebreaker. A bare rules `new` there means only
+    # "nothing to link to" — trivially true for radio housekeeping (check-ins,
+    # roll call, 10-8/10-98) — and the tiebreaker rubber-stamped it ~21/21 of the
+    # time on exactly this disagreement (CORRELATION_REVIEW_0907b.md). Any real
+    # signal (severity, coords, tags, a live same-talkgroup incident) still
+    # escalates, so an event the LLM misreads as orphan is not lost.
+    if (
+        llm_decision["action"] == "orphan"
+        and rules_decision["action"] == "new"
+        and _call_is_substanceless(ctx)
+    ):
+        logger.info(
+            f"Consensus gate for call {call_id}: llm=orphan vs rules=new and call "
+            f"is substanceless — resolving orphan, skipping tiebreak"
+        )
+        gated = {
+            "action": "orphan",
+            "matched_incident": None,
+            "incident_type": None,
+            "corr_debug": dict(rules_decision.get("corr_debug") or {}),
+        }
+        gated["corr_debug"].update({
+            "corr_consensus":     "llm_orphan_gate",
+            "corr_rules_action":  rules_decision["action"],
+            "corr_llm_action":    llm_decision["action"],
+            "corr_llm_reasoning": llm_decision.get("reasoning", ""),
+        })
+        return await incident_correlator.apply_correlation({"decision": gated, "ctx": ctx})
+
     # Disagree — escalate to the smarter tiebreaker.
     logger.info(
         f"Consensus disagreement for call {call_id}: "

drb-c2-core/tests/test_consensus_gate.py

@@ -0,0 +1,315 @@
+"""
+server-26#115 — two consensus-quality fixes.
+
+Fix 1 (routers/upload.py): when the cheap LLM says `orphan`, the rules engine
+says `new`, and the call is genuinely SUBSTANCELESS (routine severity, no
+vehicle/geocode/tag, and no incident already running on the same talkgroup),
+resolve to `orphan` and DO NOT pay for the smart tiebreaker. Radio housekeeping
+(unit check-ins, roll call, 10-8/10-98) was being promoted to incidents because
+the tiebreaker rubber-stamped the rules `new` ~21/21 of the time
+(CORRELATION_REVIEW_0907b.md).
+
+The substance test runs against `ctx` (fully populated at preview time), NOT
+against `rules_decision["corr_debug"]` — that dict is EMPTY at preview time for
+action=="new" (corr_path:"new" is written at APPLY time), so the first version of
+this gate fired on real events (a `major` "extinguishing fire", geocoded calls,
+pursuit updates).
+
+Fix 2 (incident_correlator.py): the `location` correlation path linked on a bare
+sub-`location_proximity_km` (0.5 km) distance alone, taking whichever incident
+came first in an unsorted `recent`. In a dense village two unrelated events
+routinely geocode that close. A `location` link now needs unit overlap with the
+candidate OR a distance under a tighter bar, and picks the NEAREST qualifying
+candidate. A unit-overlap location link is tagged `location_unit_overlap` so it
+does not merge into the fast path's bucket in the admin fit-signal histogram.
+"""
+from datetime import datetime, timedelta, timezone
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from app.routers import upload
+from app.internal.incident_correlator import _run_decision, has_event_substance
+
+NOW = datetime(2026, 9, 7, 21, 30, 0, tzinfo=timezone.utc)
+
+
+# ─────────────────────────────────────────────────────────────────────────────
+# Fix 1 — the LLM-orphan gate in _correlate_with_consensus
+# ─────────────────────────────────────────────────────────────────────────────
+
+def _preview(action, corr_debug=None, ctx=None):
+    base_ctx = {"call_id": "call-1"}
+    if ctx:
+        base_ctx.update(ctx)
+    return {
+        "decision": {
+            "action": action,
+            "matched_incident": None,
+            "incident_type": "other" if action == "new" else None,
+            "corr_debug": {} if corr_debug is None else dict(corr_debug),
+        },
+        "ctx": base_ctx,
+    }
+
+
+def _llm(action, reasoning="—"):
+    md = {"incident_id": "inc-1"} if action == "link" else None
+    return {"action": action, "matched_incident": md, "reasoning": reasoning}
+
+
+async def _run_consensus(preview, llm_decision):
+    tiebreak_result = {
+        "action": "new", "matched_incident": None, "incident_type": "other",
+        "corr_debug": {}, "reasoning": "tb",
+    }
+    with patch("app.internal.incident_correlator.preview_correlation",
+               new=AsyncMock(return_value=preview)), \
+         patch("app.internal.incident_correlator.apply_correlation",
+               new=AsyncMock(return_value="incident-x")) as m_apply, \
+         patch("app.internal.llm_correlator.decide",
+               new=AsyncMock(return_value=llm_decision)), \
+         patch("app.internal.llm_correlator.tiebreak",
+               new=AsyncMock(return_value=tiebreak_result)) as m_tiebreak:
+        await upload._correlate_with_consensus(
+            call_id="call-1", node_id="n1", system_id="sys-1",
+            talkgroup_id=9048, talkgroup_name="Dispatch", tags=[],
+            incident_type=None, location=None, location_coords=None,
+        )
+    return m_apply, m_tiebreak
+
+
+async def test_substanceless_no_recent_same_tg_incident_gates_without_tiebreak():
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}), _llm("orphan", "unit check-in, not an incident"),
+    )
+    m_tiebreak.assert_not_called()
+    m_apply.assert_called_once()
+    gated = m_apply.call_args[0][0]["decision"]
+    assert gated["action"] == "orphan"
+    dbg = gated["corr_debug"]
+    assert dbg["corr_consensus"] == "llm_orphan_gate"
+    assert dbg["corr_consensus"] != "tiebreak"
+    assert dbg["corr_rules_action"] == "new"
+    assert dbg["corr_llm_action"] == "orphan"
+    assert dbg["corr_llm_reasoning"] == "unit check-in, not an incident"
+
+
+@pytest.mark.parametrize("severity", ["moderate", "major"])
+async def test_moderate_or_major_severity_is_not_gated(severity):
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"call_severity": severity}), _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_routine_severity_alone_still_gates():
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"call_severity": "routine"}), _llm("orphan"),
+    )
+    m_tiebreak.assert_not_called()
+    assert m_apply.call_args[0][0]["decision"]["action"] == "orphan"
+
+
+async def test_call_with_coords_is_not_gated():
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"coords": {"lat": 41.15, "lng": -73.86}}),
+        _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_call_with_tags_is_not_gated():
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"tags": ["structure-fire"]}), _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_call_with_vehicles_is_not_gated():
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"call_vehicles": ["red sedan"]}), _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_call_with_resolved_incident_type_is_not_gated():
+    # The creation gate skips has_event_substance when a type resolved, so a
+    # typed call (fire/medical/…) opens an incident on substance the gate does
+    # not re-check — it must keep the tiebreak, not be dropped.
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"incident_type": "fire"}), _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_reassignment_call_is_not_gated():
+    # reassignment=True is dispatch pulling a unit onto a NEW job (units are
+    # blanked for exactly that reason) — the strongest new-incident signal.
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx={"reassignment": True}), _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_recent_incident_on_same_talkgroup_is_not_gated():
+    ctx = {
+        "system_id": "sys-1",
+        "talkgroup_id": 9048,
+        "recent": [{
+            "incident_id": "inc-live",
+            "system_ids": ["sys-1"],
+            "talkgroup_ids": ["9048"],
+        }],
+    }
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx=ctx), _llm("orphan"),
+    )
+    m_tiebreak.assert_called_once()
+
+
+async def test_recent_incident_on_a_different_talkgroup_still_gates():
+    ctx = {
+        "system_id": "sys-1",
+        "talkgroup_id": 9048,
+        "recent": [{
+            "incident_id": "inc-other",
+            "system_ids": ["sys-1"],
+            "talkgroup_ids": ["1200"],
+        }],
+    }
+    m_apply, m_tiebreak = await _run_consensus(
+        _preview("new", {}, ctx=ctx), _llm("orphan"),
+    )
+    m_tiebreak.assert_not_called()
+    assert m_apply.call_args[0][0]["decision"]["action"] == "orphan"
+
+
+async def test_llm_link_vs_rules_new_still_escalates():
+    m_apply, m_tiebreak = await _run_consensus(_preview("new", {}), _llm("link", "same job"))
+    m_tiebreak.assert_called_once()
+
+
+async def test_llm_orphan_vs_rules_link_still_escalates():
+    # Not the gate condition (gate needs rules=="new"); must fall through.
+    m_apply, m_tiebreak = await _run_consensus(_preview("link", {}), _llm("orphan"))
+    m_tiebreak.assert_called_once()
+
+
+def test_has_event_substance_predicate():
+    assert has_event_substance({"coords": {"lat": 1, "lng": 2}})
+    assert has_event_substance({"tags": ["fire"]})
+    assert has_event_substance({"call_vehicles": ["sedan"]})
+    assert not has_event_substance({})
+    assert not has_event_substance({"coords": None, "tags": [], "call_vehicles": []})
+    # units and location are NOT substance — nearly every transmission has them.
+    assert not has_event_substance({"call_units": ["7-Adam"], "location": "Main St"})
+
+
+# ─────────────────────────────────────────────────────────────────────────────
+# Fix 2 — tighten corr_path=location
+# ─────────────────────────────────────────────────────────────────────────────
+
+CALL_COORDS = {"lat": 41.150000, "lng": -73.860000}
+# ~0.39 km north of the call — inside location_proximity_km (0.5) but well
+# outside the tight bar (_LOCATION_TIGHT_PROXIMITY_KM, 0.2).
+FAR_INC_COORDS = {"lat": 41.153500, "lng": -73.860000}
+# ~0.13 km north of the call — inside the tight bar.
+NEAR_INC_COORDS = {"lat": 41.151200, "lng": -73.860000}
+# ~0.28 km north — inside the 0.5 radius, outside the 0.2 tight bar; used as a
+# second candidate that must lose the nearest-wins sort to NEAR_INC_COORDS.
+MID_INC_COORDS = {"lat": 41.152500, "lng": -73.860000}
+
+
+def _inc(incident_id, coords, units):
+    return {
+        "incident_id": incident_id,
+        "system_ids": ["sys-1"],
+        "talkgroup_ids": ["100"],           # different TGID → fast path is a no-op
+        "location_coords": coords,
+        "units": units,
+        "tags": [],
+        "type": "police",
+        "updated_at": (NOW - timedelta(minutes=6)).isoformat(),
+        "started_at": (NOW - timedelta(minutes=20)).isoformat(),
+        "status": "active",
+        "call_ids": ["c0"],
+    }
+
+
+def _loc_ctx(*, incidents, call_units):
+    return {
+        "call_id": "call-loc",
+        "all_active": list(incidents),
+        "recent": list(incidents),
+        "call_doc": {},
+        "call_embedding": None,
+        "call_units": call_units,
+        "call_vehicles": [],
+        "call_cleared": [],
+        "call_severity": "routine",
+        "coords": CALL_COORDS,
+        "is_thin_call": False,
+        "now": NOW,
+        "system_id": "sys-1",
+        "talkgroup_id": 999,               # not in inc.talkgroup_ids
+        "talkgroup_name": "Tactical",
+        "tags": [],
+        "incident_type": "police",
+        "location": "Main St",
+        "location_coords": CALL_COORDS,
+        "reassignment": True,              # suppress the unit-continuity path
+        "create_if_new": True,
+    }
+
+
+def test_location_path_in_radius_but_no_unit_overlap_no_tight_proximity_does_not_link(caplog):
+    ctx = _loc_ctx(
+        incidents=[_inc("inc-loc", FAR_INC_COORDS, ["7-Adam"])],
+        call_units=["3-Boy"],
+    )
+    with caplog.at_level("INFO", logger="drb-c2-core"):
+        decision = _run_decision(ctx)
+    # Reaches, and is rejected by, the new guard (not an earlier path).
+    assert "location-path skipped" in caplog.text
+    assert decision["action"] != "link"
+    assert (decision.get("corr_debug") or {}).get("corr_path") != "location"
+
+
+def test_location_path_links_on_unit_overlap_with_distinct_fit_signal():
+    ctx = _loc_ctx(
+        incidents=[_inc("inc-loc", FAR_INC_COORDS, ["5-Adam"])],
+        call_units=["5-Adam"],
+    )
+    decision = _run_decision(ctx)
+    assert decision["action"] == "link"
+    assert decision["corr_debug"]["corr_path"] == "location"
+    # NOT "unit_overlap" — that value belongs to the fast path's histogram bucket.
+    assert decision["corr_debug"]["corr_fit_signal"] == "location_unit_overlap"
+
+
+def test_location_path_links_on_tight_proximity_without_unit_overlap():
+    ctx = _loc_ctx(
+        incidents=[_inc("inc-loc", NEAR_INC_COORDS, ["7-Adam"])],
+        call_units=["3-Boy"],
+    )
+    decision = _run_decision(ctx)
+    assert decision["action"] == "link"
+    assert decision["corr_debug"]["corr_path"] == "location"
+    assert decision["corr_debug"]["corr_fit_signal"] == "location_proximity"
+
+
+def test_location_path_picks_nearest_in_radius_candidate():
+    # `recent` order puts the farther tight-proximity incident first; the guard
+    # must still select the nearest one.
+    ctx = _loc_ctx(
+        incidents=[
+            _inc("inc-mid", MID_INC_COORDS, ["3-Boy"]),   # ~0.28 km, tight-fail
+            _inc("inc-near", NEAR_INC_COORDS, ["3-Boy"]),  # ~0.13 km, tight-pass
+        ],
+        call_units=["3-Boy"],
+    )
+    decision = _run_decision(ctx)
+    assert decision["action"] == "link"
+    assert decision["matched_incident"]["incident_id"] == "inc-near"
+    assert decision["corr_debug"]["corr_path"] == "location"