511NY DOT cameras + traffic events map layers (#183)

GET /traffic/511 serves a bbox slice of the statewide 511NY camera and event
feeds from an in-memory cache (cameras 1h, events 2m TTL, fetched lazily) --
public data, so no Firestore writes. A failed refresh keeps the last good data
and reports the error; a schema change (nothing parses) is an error, not an
empty layer. Frontend: opt-in "DOT Cameras" and "Traffic Events" overlays that
fetch only while shown, with an on-map notice when the feed is down or stale.
NY511_API_KEY is optional in config (the API answers without one today; the
terms require a registered key).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-c2-core/app/internal/ny511.py

@@ -0,0 +1,140 @@
+"""511NY (NYSDOT) traffic cameras and events, cached in memory (server-26#183).
+
+Public data, identical for every org, so it is NOT written to Firestore: the
+statewide feeds are ~3k cameras and ~2.3k events, and re-writing them every
+poll would be millions of writes a day for data nobody needs history of. The
+cache is filled lazily on request and refreshed per TTL, so an idle deploy
+makes no 511 calls at all.
+
+A failed refresh keeps serving the last good data and reports the error and
+its age to the caller -- an empty layer must never be the only symptom of a
+dead feed (the AI-silent-failures lesson).
+"""
+import asyncio
+import time
+from datetime import datetime
+from typing import Any, Dict, List, Optional
+
+import httpx
+
+from app.config import settings
+from app.internal.logger import logger
+
+_BASE = "https://511ny.org/api"
+CAMERAS_TTL_S = 60 * 60   # camera list is near-static
+EVENTS_TTL_S = 2 * 60     # accidents/closures change minute to minute
+RETRY_AFTER_FAILURE_S = 60
+_DESCRIPTION_MAX = 500
+
+
+class _Feed:
+    def __init__(self, path: str, ttl_s: int, normalize):
+        self.path = path
+        self.ttl_s = ttl_s
+        self.normalize = normalize
+        self.items: List[Dict[str, Any]] = []
+        self.fetched_at: Optional[float] = None   # epoch s of last SUCCESSFUL fetch
+        self.error: Optional[str] = None
+        self._next_attempt = 0.0
+        self._lock = asyncio.Lock()
+
+    async def get(self) -> "_Feed":
+        if time.time() < self._next_attempt:
+            return self
+        async with self._lock:
+            if time.time() < self._next_attempt:
+                return self   # another request refreshed while we waited
+            try:
+                self.items = await _fetch(self.path, self.normalize)
+                self.fetched_at = time.time()
+                self.error = None
+                self._next_attempt = time.time() + self.ttl_s
+            except Exception as e:
+                self._next_attempt = time.time() + min(self.ttl_s, RETRY_AFTER_FAILURE_S)
+                self.error = f"{type(e).__name__}: {e}"[:300]
+                logger.warning(f"511NY {self.path} refresh failed, serving {len(self.items)} cached: {self.error}")
+        return self
+
+
+async def _fetch(path: str, normalize) -> List[Dict[str, Any]]:
+    params = {"format": "json"}
+    if settings.ny511_api_key:
+        params["key"] = settings.ny511_api_key
+    async with httpx.AsyncClient(timeout=20.0) as client:
+        r = await client.get(f"{_BASE}/{path}", params=params)
+        r.raise_for_status()
+        raw = r.json()
+    if not isinstance(raw, list):
+        raise ValueError(f"expected a JSON list, got {type(raw).__name__}")
+    out = [n for n in (normalize(x) for x in raw) if n is not None]
+    if raw and not out:
+        # every record failed to normalize: the schema changed under us
+        raise ValueError(f"0 of {len(raw)} records parsed -- 511NY schema change?")
+    return out
+
+
+def _coords(x: Dict[str, Any]) -> Optional[tuple]:
+    try:
+        lat, lon = float(x["Latitude"]), float(x["Longitude"])
+    except (KeyError, TypeError, ValueError):
+        return None
+    if lat == 0 and lon == 0:
+        return None
+    return lat, lon
+
+
+def _local_iso(s: Any) -> Optional[str]:
+    """511NY stamps are 'DD/MM/YYYY HH:MM:SS' New York local time. Returned as a
+    naive ISO string (no offset) -- display-only, never compared to UTC."""
+    if not s:
+        return None
+    try:
+        return datetime.strptime(s, "%d/%m/%Y %H:%M:%S").isoformat()
+    except (TypeError, ValueError):
+        return None
+
+
+def normalize_camera(x: Dict[str, Any]) -> Optional[Dict[str, Any]]:
+    c = _coords(x)
+    if c is None or x.get("Disabled") or x.get("Blocked") or not x.get("ID"):
+        return None
+    return {
+        "id": x["ID"],
+        "lat": c[0],
+        "lon": c[1],
+        "name": x.get("Name") or "",
+        "roadway": x.get("RoadwayName") or "",
+        "direction": x.get("DirectionOfTravel") or "",
+        "image_url": x.get("Url"),      # 511NY serves the current still at this URL
+        "video_url": x.get("VideoUrl"),  # HLS playlist, when the camera streams
+    }
+
+
+def normalize_event(x: Dict[str, Any]) -> Optional[Dict[str, Any]]:
+    c = _coords(x)
+    if c is None or not x.get("ID"):
+        return None
+    desc = x.get("Description") or ""
+    return {
+        "id": x["ID"],
+        "lat": c[0],
+        "lon": c[1],
+        "type": x.get("EventType") or "",
+        "subtype": x.get("EventSubType") or "",
+        "severity": x.get("Severity") or "",
+        "roadway": x.get("RoadwayName") or "",
+        "direction": x.get("DirectionOfTravel") or "",
+        "county": x.get("CountyName") or "",
+        "description": desc[:_DESCRIPTION_MAX] + ("…" if len(desc) > _DESCRIPTION_MAX else ""),
+        "start_local": _local_iso(x.get("StartDate")),
+        "planned_end_local": _local_iso(x.get("PlannedEndDate")),
+        "updated_local": _local_iso(x.get("LastUpdated")),
+    }
+
+
+cameras = _Feed("getcameras", CAMERAS_TTL_S, normalize_camera)
+events = _Feed("getevents", EVENTS_TTL_S, normalize_event)
+
+
+def in_bbox(items: List[Dict[str, Any]], south: float, west: float, north: float, east: float) -> List[Dict[str, Any]]:
+    return [i for i in items if south <= i["lat"] <= north and west <= i["lon"] <= east]