Add ADS-B, AIS, and ALPR map layers with live CoT streaming.

Ingest aircraft and vessel tracks via OSINT feeds and tactical CoT, expose viewport-filtered SSE to the map, and add an OSM ALPR layer with tiled caching and performant marker sync.

server/utils/cotSubscribers.js

@@ -0,0 +1,70 @@
+/** SSE subscriber registry; bbox union drives OSINT feeds. */
+
+import { getActiveEntitiesInBbox } from './cotStore.js'
+import { isInBbox, matchesLayerFilter, unionBboxes } from './cotEntityUtils.js'
+
+/** @typedef {{ west: number, south: number, east: number, north: number }} Bbox */
+/** @typedef {(event: string, data: string) => Promise<void> | void} PushFn */
+
+/** @type {Map<string, { bbox: Bbox | null, layers: Set<string>, push: PushFn }>} */
+const subscribers = new Map()
+let nextId = 1
+
+/**
+ * @param {{ bbox: Bbox | null, layers: Set<string>, push: PushFn }} sub
+ * @returns {() => void} Unregister function.
+ */
+export function registerSubscriber(sub) {
+  const id = String(nextId++)
+  subscribers.set(id, sub)
+  return () => subscribers.delete(id)
+}
+
+/** @returns {Bbox | null} Union of all subscriber bboxes. */
+export function getSubscriberBboxUnion() {
+  return unionBboxes([...subscribers.values()].map(s => s.bbox))
+}
+
+export function getSubscriberCount() {
+  return subscribers.size
+}
+
+export function clearSubscribers() {
+  subscribers.clear()
+}
+
+export async function notifySubscribersForEntity(event, payload, entity) {
+  const data = JSON.stringify(payload)
+  const tasks = []
+  for (const sub of subscribers.values()) {
+    if (sub.bbox && !isInBbox(entity, sub.bbox)) continue
+    if (!matchesLayerFilter(sub.layers, entity)) continue
+    tasks.push(Promise.resolve(sub.push(event, data)))
+  }
+  await Promise.all(tasks)
+}
+
+export async function notifySubscribersRemove(id) {
+  const data = JSON.stringify({ id })
+  await Promise.all(
+    [...subscribers.values()].map(sub => Promise.resolve(sub.push('remove', data))),
+  )
+}
+
+/**
+ * Push a filtered snapshot to each active SSE subscriber.
+ * @param {{ ttlMs?: number, osintTtlMs?: number, takFilterBbox?: boolean, maxEntities?: number }} snapshotOpts
+ */
+export async function broadcastSubscriberSnapshots(snapshotOpts) {
+  const tasks = []
+  for (const sub of subscribers.values()) {
+    tasks.push((async () => {
+      const entities = await getActiveEntitiesInBbox(sub.bbox, {
+        ...snapshotOpts,
+        layers: sub.layers,
+      })
+      await sub.push('snapshot', JSON.stringify({ entities }))
+    })())
+  }
+  await Promise.all(tasks)
+}