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-frontend/lib/c2api.ts

@@ -1,5 +1,5 @@
 import { auth } from "@/lib/firebase";
-import type { AreaContext, TalkgroupPending } from "@/lib/types";
+import type { AreaContext, Ny511Response, TalkgroupPending } from "@/lib/types";
 
 const BASE = process.env.NEXT_PUBLIC_C2_URL ?? "http://localhost:8000";
 
@@ -370,6 +370,12 @@ export const c2api = {
   revokeEnrollmentToken: (tokenId: string) =>
     request(`/org/enrollment-tokens/${tokenId}`, { method: "DELETE" }),
 
+  // 511NY cameras/events inside a map bbox (server-26#183)
+  get511: (bbox: { south: number; west: number; north: number; east: number }, layers: string) =>
+    request<Ny511Response>(`/traffic/511?${new URLSearchParams({
+      south: String(bbox.south), west: String(bbox.west), north: String(bbox.north), east: String(bbox.east), layers,
+    })}`),
+
   // Public waitlist — no auth, see routers/waitlist.py
   joinWaitlist: (body: { email: string; org_name?: string; note?: string }) =>
     request<{ ok: boolean }>("/waitlist", { method: "POST", body: JSON.stringify(body) }),

drb-frontend/lib/types.ts

@@ -98,6 +98,49 @@ export interface VesselTrack {
   last_seen: string;
 }
 
+// 511NY traffic layer (server-26#183) — GET /traffic/511, cached server-side,
+// not Firestore. *_local times are New York local, no offset: display only.
+export interface Ny511Camera {
+  id: string;
+  lat: number;
+  lon: number;
+  name: string;
+  roadway: string;
+  direction: string;
+  image_url: string | null;
+  video_url: string | null;
+}
+
+export interface Ny511Event {
+  id: string;
+  lat: number;
+  lon: number;
+  type: string;
+  subtype: string;
+  severity: string;
+  roadway: string;
+  direction: string;
+  county: string;
+  description: string;
+  start_local: string | null;
+  planned_end_local: string | null;
+  updated_local: string | null;
+}
+
+export interface Ny511FeedStatus {
+  fetched_at: number | null;  // epoch seconds of the last successful 511NY fetch
+  error: string | null;       // set when the latest refresh failed (data is then stale)
+  total_in_bbox: number;
+  truncated: boolean;
+}
+
+export interface Ny511Response {
+  cameras?: Ny511Camera[];
+  cameras_status?: Ny511FeedStatus;
+  events?: Ny511Event[];
+  events_status?: Ny511FeedStatus;
+}
+
 export interface VocabularyPendingTerm {
   term: string;
   source: "induction" | "correction";

drb-frontend/lib/use511.ts

@@ -0,0 +1,57 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import type L from "leaflet";
+import { c2api } from "@/lib/c2api";
+import type { Ny511Response } from "@/lib/types";
+
+// 511NY cameras/events for the current map view (server-26#183). Unlike
+// useAircraft/useVessels this is not a Firestore listener: the data is public
+// and statewide, so c2-core caches it in memory and serves a bbox slice.
+// Fetches only while `enabled` (the overlay is on), on pan/zoom (debounced),
+// and on a poll matching the server's events TTL.
+const POLL_MS = 2 * 60 * 1000;
+const MOVE_DEBOUNCE_MS = 400;
+const BBOX_PAD = 0.2;   // fetch a little past the edges so small pans don't blank the layer
+
+export function use511(map: L.Map, layers: "cameras" | "events", enabled: boolean) {
+  const [data, setData] = useState<Ny511Response>({});
+  const [error, setError] = useState<string | null>(null);
+  const seq = useRef(0);
+
+  useEffect(() => {
+    if (!enabled) { setData({}); return; }
+    let debounce: ReturnType<typeof setTimeout> | undefined;
+
+    const load = async () => {
+      const b = map.getBounds().pad(BBOX_PAD);
+      const mine = ++seq.current;
+      try {
+        const res = await c2api.get511(
+          { south: b.getSouth(), west: b.getWest(), north: b.getNorth(), east: b.getEast() },
+          layers,
+        );
+        if (mine !== seq.current) return;   // a newer pan's response wins
+        setData(res);
+        setError(null);
+      } catch (e) {
+        if (mine !== seq.current) return;
+        console.error("use511:", e);
+        setError(e instanceof Error ? e.message : String(e));
+      }
+    };
+    const onMove = () => { clearTimeout(debounce); debounce = setTimeout(load, MOVE_DEBOUNCE_MS); };
+
+    load();
+    map.on("moveend", onMove);
+    const poll = setInterval(load, POLL_MS);
+    return () => {
+      map.off("moveend", onMove);
+      clearTimeout(debounce);
+      clearInterval(poll);
+      seq.current++;   // drop any in-flight response
+    };
+  }, [map, layers, enabled]);
+
+  return { data, error };
+}