fix(3-M.b): apply_enrichment always attaches _enriched for declared adapters

Coordless events such as removal tombstones with null lat/lon, from adapters that declare enrichment_locations, previously fell off the loop without writing _enriched and carried no geocoder bundle at all, violating the every-event-carries-_enriched design rule. Add a post-loop fallback that resolves the null location to an all-null bundle per enricher. Adapters with no enrichment_locations remain skipped.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_apply_enrichment_coordless.py

@@ -0,0 +1,78 @@
+"""Regression tests for apply_enrichment's coordless path.
+
+Design principle: every event from an adapter that declares enrichment_locations
+must carry data["_enriched"] — populated when coordinates resolve, an all-null
+bundle when they don't (e.g. removal tombstones with no lat/lon). Adapters that
+declare no enrichment_locations are still skipped entirely.
+"""
+
+from datetime import datetime, timezone
+from typing import Any
+
+import pytest
+
+from central.config_models import EnrichmentConfig
+from central.enrichment.cache import EnrichmentCache
+from central.enrichment.geocoder import GeocoderEnricher, all_null_bundle
+from central.models import Event, Geo
+from central.supervisor import apply_enrichment, build_enrichers
+
+
+def _make_event(data: dict[str, Any]) -> Event:
+    return Event(
+        id="evt-1",
+        adapter="usgs_quake",
+        category="quake.event.test",
+        time=datetime(2026, 1, 1, tzinfo=timezone.utc),
+        geo=Geo(),
+        data=data,
+    )
+
+
+class _PopulatingBackend:
+    """Deterministic backend that resolves any real coords to a fixed place."""
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        return {**all_null_bundle(), "city": "Boise", "state": "ID"}
+
+
+@pytest.mark.asyncio
+async def test_coordless_event_with_declared_locations_gets_null_bundle(tmp_path):
+    """An event whose declared coord paths are all None still gets _enriched."""
+    cache = EnrichmentCache(tmp_path / "enrichment_cache.db")
+    enrichers = build_enrichers(EnrichmentConfig(), cache)
+    event = _make_event(
+        {"latitude": None, "longitude": None, "reason": "fallen_off_current_service"}
+    )
+    assert "_enriched" not in event.data
+
+    await apply_enrichment(event, [("latitude", "longitude")], enrichers)
+
+    assert event.data["_enriched"]["geocoder"] == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_event_with_coords_still_enriches_normally(tmp_path):
+    """The coord-bearing path is unchanged: the backend is consulted and its
+    resolved fields land in the bundle."""
+    cache = EnrichmentCache(tmp_path / "enrichment_cache.db")
+    enricher = GeocoderEnricher(_PopulatingBackend(), cache=cache)
+    event = _make_event({"latitude": 43.0, "longitude": -116.0})
+
+    await apply_enrichment(event, [("latitude", "longitude")], [enricher])
+
+    bundle = event.data["_enriched"]["geocoder"]
+    assert bundle["state"] == "ID"
+    assert bundle["city"] == "Boise"
+
+
+@pytest.mark.asyncio
+async def test_adapter_with_no_enrichment_locations_still_skipped(tmp_path):
+    """Adapters declaring no enrichment_locations are skipped — no _enriched."""
+    cache = EnrichmentCache(tmp_path / "enrichment_cache.db")
+    enrichers = build_enrichers(EnrichmentConfig(), cache)
+    event = _make_event({"latitude": 43.0, "longitude": -116.0})
+
+    await apply_enrichment(event, [], enrichers)
+
+    assert "_enriched" not in event.data