fix(cctv): space out failed background refreshes; test the stale paths

- A background catalog refresh that rejects now keeps the old catalog for
  another TTL, as an empty refresh already did, so a refresh that keeps
  failing is retried once per TTL instead of on every request.
- Trim notes are keyed by the source list they describe, and /sources asks
  for the list it served, so a request answered during a refresh never pairs
  the old cameras with the new list's notes.
- Tests: a failed background refresh (one warning, no unhandled rejection,
  no retry before the TTL, trim notes stay with their list) and an empty
  background refresh (old catalog kept, no upstream fetch before the TTL).
  The race assertion's message now names the failure; its timer is cleared.
- The Tarktee test no longer imports the new constant, so on main it fails
  on its own assertion instead of taking the whole file down.
- precompute-cctv-heights waits 60 s for a cold catalog, past Tarktee's 30 s.
- CURRENT-STATE notes the 30 s bound and the retry spacing.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

server/providers/cctv.js

@@ -143,7 +143,7 @@ export function cctvProxy({ sourceRoot = process.cwd() } = {}) {
 
         if (url.pathname === '/sources') {
           const body = {
-            trimmedPacks: getCctvSources.trimmedPacks?.() ?? [],
+            trimmedPacks: getCctvSources.trimmedPacks?.(sources) ?? [],
             sources: sources.map((source) => ({
               id: source.id,
               pack: source.pack,

server/providers/cctv/catalog.js

@@ -195,9 +195,11 @@ export function createCctvCatalog({ sourceRoot = process.cwd() } = {}) {
   /** @type {Promise<Array<object>>|null} In-flight refresh, shared by concurrent
    * callers so a post-TTL burst launches ONE refetch, not one per request. */
   let _cctvSourceInflight = null;
-  /** @type {Array<{pack: string, available: number, served: number}>} Packs
-   * that serve fewer cameras than they offer. */
-  let _cctvTrimmedPacks = [];
+  /** @type {WeakMap<Array<object>, Array<{pack: string, available: number, served: number}>>}
+   * Packs that serve fewer cameras than they offer, keyed by the source list
+   * they describe, so a request served the old list during a background
+   * refresh never pairs it with the new list's trim notes. */
+  const _cctvTrimmedPacks = new WeakMap();
 
   /**
    * Assemble and cache the merged CCTV source list.
@@ -225,11 +227,16 @@ export function createCctvCatalog({ sourceRoot = process.cwd() } = {}) {
         _cctvSourceInflight = null;
       });
       // A background refresh has no caller waiting on it: report its failure
-      // here, once per refresh rather than once per request it serves.
+      // here, once per refresh rather than once per request it serves. Keep
+      // the old catalog for another TTL, as an empty refresh does, so a refresh
+      // that keeps failing is retried once per TTL, not back to back.
       if (_cctvSourceCache.length) {
         _cctvSourceInflight.catch((error) => {
+          _cctvSourceCacheAt = Date.now();
           console.warn(
-            '[CCTV] background catalog refresh failed:',
+            '[CCTV] background catalog refresh failed; serving',
+            _cctvSourceCache.length,
+            'cameras from the last catalog:',
             error?.message || error,
           );
         });
@@ -329,7 +336,7 @@ export function createCctvCatalog({ sourceRoot = process.cwd() } = {}) {
     }
     if (capped.length > 0 || _cctvSourceCache.length === 0) {
       _cctvSourceCache = capped;
-      _cctvTrimmedPacks = trimmedPacks;
+      _cctvTrimmedPacks.set(capped, trimmedPacks);
     } else {
       // Every source came back empty (all live packs timed out / upstream outage)
       // but a good catalog is already cached — serve it stale rather than blanking
@@ -343,7 +350,10 @@ export function createCctvCatalog({ sourceRoot = process.cwd() } = {}) {
     return _cctvSourceCache;
   }
 
-  /** Packs serving fewer cameras than they offer, as of the last refresh. */
-  getCctvSources.trimmedPacks = () => _cctvTrimmedPacks;
+  /** Packs serving fewer cameras than they offer in `sources` (by default the
+   * current catalog). Pass the list a request was served to keep the two in
+   * step while a background refresh swaps the catalog. */
+  getCctvSources.trimmedPacks = (sources = _cctvSourceCache) =>
+    _cctvTrimmedPacks.get(sources) ?? [];
   return getCctvSources;
 }