fix(vessels): protect Hormuz VesselAPI rows from AISStream eviction

AISStream's live US-coast feed crowds vessel_last_known past _MAX_VESSELS
(6000) and the 'evict oldest seen_at' pass reaps the Hormuz VesselAPI rows,
which are only refreshed every VESSELAPI_INTERVAL (~4.8h). Result: the poller
was fetching 50 Hormuz vessels per 2xx but /api/vessels?bbox=Hormuz stayed
empty. Eviction now skips src=vesselapi rows (falls back to evictable-only,
clamped) so the blind-spot box stays resident between polls.

app/live_layers.py

@@ -993,8 +993,18 @@ async def upsert_vessel(marker: dict) -> None:
         vessel_last_known[vid] = stored
         if len(vessel_last_known) > _MAX_VESSELS:
             excess = len(vessel_last_known) - int(_MAX_VESSELS * 0.9)
+            # AISStream's live US-coast feed can crowd the shared store past
+            # _MAX_VESSELS and evict the Hormuz VesselAPI rows (refreshed only
+            # every VESSELAPI_INTERVAL) as "oldest". Keep src=vesselapi rows
+            # resident so the blind-spot box stays visible between polls.
+            evictable = [
+                k for k, v in vessel_last_known.items()
+                if (v.get("extra") or {}).get("src") != "vesselapi"
+            ]
+            if len(evictable) < excess:
+                excess = len(evictable)
             oldest = sorted(
-                vessel_last_known,
+                evictable,
                 key=lambda k: vessel_last_known[k].get("seen_at", ""),
             )[:excess]
             for k in oldest:

tests/test_vesselapi.py

@@ -298,6 +298,40 @@ def _make_get_client(client):
     return _get_client
 
 
+def test_eviction_keeps_vesselapi_rows(monkeypatch):
+    """AISStream crowding past _MAX_VESSELS must not reap Hormuz VesselAPI rows."""
+    from ws_manager import manager
+    from live_layers import _MAX_VESSELS, upsert_vessel
+
+    _patch_side_effects(monkeypatch)
+    monkeypatch.setattr("live_layers._MAX_VESSELS", 10)
+    vessel_last_known.clear()
+    manager._queues.clear()
+    manager._viewports.clear()
+
+    # One Hormuz VesselAPI row with the oldest seen_at — the first thing the
+    # old "evict oldest" logic would reap — plus enough AISStream rows to
+    # exceed the cap.
+    vessel_last_known["422050100"] = {
+        "id": "422050100", "lat": 26.5, "lon": 56.3, "label": "HORMUZ STAR",
+        "extra": {"src": "vesselapi"}, "seen_at": "2026-08-29T00:00:00+00:00",
+    }
+    for i in range(10):
+        vid = f"3{i:08d}"
+        vessel_last_known[vid] = {
+            "id": vid, "lat": 35.0 + i * 0.01, "lon": -79.0, "label": vid,
+            "extra": {"src": "aisstream"},
+            "seen_at": f"2026-08-29T0{i}:00:00+00:00",
+        }
+
+    # One more AISStream marker pushes past the cap and triggers eviction.
+    asyncio.run(upsert_vessel({"id": "399999999", "lat": 36.0, "lon": -78.0, "label": "NEW"}))
+
+    assert "422050100" in vessel_last_known  # VesselAPI row survives
+    assert vessel_last_known["422050100"]["extra"]["src"] == "vesselapi"
+    assert len(vessel_last_known) <= 10
+
+
 # ── Independent-provider idle behaviour ───────────────────────────────────
 # VesselAPI must never be gated on AISStream (or vice versa): a missing key on
 # one provider leaves the other running. ``_StopLoop`` is a BaseException so