correlator/admin: capture per-scene incident_type + severity (#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 window-4 dump analysis couldn't tell apart from
cross-scene contamination without re-guessing from a live dump. Adds
incident_type/severity to _apply_and_log's per-scene write and to admin.py's
_scene_summary allowlist (the debug-dump reader has its own field allowlist,
separate from the write side — silently would not have surfaced otherwise).

Sandboxed pytest: 380 -> 381.

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

drb-c2-core/tests/test_per_scene_call_doc.py

@@ -123,10 +123,60 @@ 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. Each scene's own scenes.<n>
+    entry must carry its own incident_type/severity, distinct from any other
+    scene on the same call.
+    """
+    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": "routine",
+    }
+
+    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)
+
+    scenes = docs[("calls", "call-5")]["scenes"]
+    assert scenes["0"]["incident_type"] == "traffic-stop"
+    assert scenes["0"]["severity"] == "routine"
+    assert scenes["1"]["incident_type"] is None
+    # _apply_and_log never writes incident_type/severity to the flat
+    # top-level fields at all (only corr_debug's own keys go flat) — the
+    # per-scene entry is the only place either value is ever persisted.
+
+
 @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