correlator: address drb-correlation-review notes on #139

- Document call_severity's routine-coercion asymmetry with incident_type
  (extraction-said-routine vs extraction-said-nothing look identical).
- Test docstring no longer overclaims the ctx-linkage it doesn't cover;
  points to the tests that do (test_consensus_gate.py, test_incident_identity.py).
- scene1 now uses a distinct severity so the test actually exercises both
  fields symmetrically; the 'no flat top-level clobber' claim is now
  asserted, not just commented.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Tbknwttzou4s46PAykmtix

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

@@ -1461,6 +1461,21 @@ async def _apply_and_log(decision: dict, ctx: dict) -> Optional[str]:
                 "transcript":    ctx.get("scene_transcript"),
                 "incident_id":   incident_id,
                 "corr_debug":    corr_debug,
+                # server-26#139: this scene's OWN extracted incident_type/
+                # severity, as read by _call_is_substanceless's ctx at
+                # decision time — not the call doc's flat top-level field,
+                # which is last-scene-wins (server-26#96) and was the reason
+                # #138's "type" veto couldn't be told apart from cross-scene
+                # contamination without re-guessing from a live dump.
+                # NOTE: unlike incident_type, call_severity is already
+                # coerced to "routine" when extraction emitted nothing
+                # (ctx build: `severity or "routine"`) — a scene reading
+                # "routine" here doesn't distinguish "extraction said
+                # routine" from "extraction said nothing". Don't split a
+                # severity veto the way #138 splits the type veto without
+                # accounting for that.
+                "incident_type": ctx.get("incident_type"),
+                "severity":      ctx.get("call_severity"),
             }
         }
         try:

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

@@ -109,6 +109,11 @@ async def debug_correlation(
             "scene_index":            scene_index,
             "transcript":             scene.get("transcript"),
             "incident_id":            scene.get("incident_id"),
+            # server-26#139: this scene's OWN incident_type/severity, as seen
+            # by _call_is_substanceless at decision time — not the call doc's
+            # flat top-level field, which is last-scene-wins (server-26#96).
+            "incident_type":          scene.get("incident_type"),
+            "severity":               scene.get("severity"),
             "corr_path":              corr_debug.get("corr_path"),
             "corr_incident_idle_min": corr_debug.get("corr_incident_idle_min"),
             "corr_distance_km":       corr_debug.get("corr_distance_km"),

drb-c2-core/tests/test_per_scene_call_doc.py

@@ -123,10 +123,66 @@ async def test_single_scene_call_still_gets_a_scenes_map_equivalent_to_flat_fiel
             "transcript": "10-4",
             "incident_id": None,
             "corr_debug": {"corr_path": "fast/thin", "corr_consensus": "rules_only"},
+            "incident_type": None,
+            "severity": None,
         }
     }
 
 
+@pytest.mark.asyncio
+async def test_scene_entry_captures_its_own_incident_type_not_a_sibling_scenes():
+    """
+    server-26#139: _call_is_substanceless's "type" veto reads ctx["incident_type"]
+    at decision time, but that value was never persisted per-scene — only the
+    last-scene-wins flat field, which #138's dump analysis couldn't
+    distinguish from cross-scene contamination. Pins _apply_and_log's write
+    side: each scene's own scenes.<n> entry carries its own incident_type/
+    severity, distinct from any other scene on the same call. Does NOT cover
+    whether the ctx handed to _call_is_substanceless is the same object that
+    reaches here — that linkage is pinned by test_consensus_gate.py and
+    test_incident_identity.py, not this file.
+    """
+    docs: dict[tuple, dict] = {}
+
+    async def fake_doc_set(collection, doc_id, data, merge=True):
+        docs.setdefault((collection, doc_id), {})
+        _merge(docs[(collection, doc_id)], data)
+
+    decision0 = {
+        "action": "orphan", "matched_incident": None, "incident_type": None,
+        "corr_debug": {"corr_path": "new", "corr_consensus": "tiebreak", "corr_gate_veto": "type"},
+    }
+    ctx0 = {
+        "call_id": "call-5", "scene_index": 0, "scene_transcript": "10-4, clear",
+        "incident_type": "traffic-stop", "call_severity": "routine",
+    }
+
+    decision1 = {
+        "action": "orphan", "matched_incident": None, "incident_type": None,
+        "corr_debug": {"corr_path": "new", "corr_consensus": "agreed"},
+    }
+    ctx1 = {
+        "call_id": "call-5", "scene_index": 1, "scene_transcript": "roll call",
+        "incident_type": None, "call_severity": "moderate",
+    }
+
+    with patch.object(incident_correlator, "fstore") as mock_fstore:
+        mock_fstore.doc_set = fake_doc_set
+        await incident_correlator._apply_and_log(decision0, ctx0)
+        await incident_correlator._apply_and_log(decision1, ctx1)
+
+    doc = docs[("calls", "call-5")]
+    scenes = doc["scenes"]
+    assert scenes["0"]["incident_type"] == "traffic-stop"
+    assert scenes["0"]["severity"] == "routine"
+    assert scenes["1"]["incident_type"] is None
+    assert scenes["1"]["severity"] == "moderate"
+    # _apply_and_log only ever flat-merges corr_debug's own keys (:1460) — a
+    # future corr_debug["incident_type"] would silently clobber
+    # intelligence.py's flat field, so this is asserted, not just commented.
+    assert "incident_type" not in doc
+
+
 @pytest.mark.asyncio
 async def test_empty_corr_debug_writes_nothing_same_as_before():
     """Preserve the pre-#96 short-circuit: no corr_debug means no write at