feat: close STREAMING.md production readiness gaps

- Added run ID + unique segment naming (r-{ISOTIME}/seg-{seq}.m4s)
- Added fsnotify watcher for real-time R2 segment upload (~7s)
- Added atomic manifest publication (temp key → CopyObject)
- Fixed manifest Cache-Control: public, max-age=1, s-maxage=2, must-revalidate
- Added hls.js error recovery: bounded retries (5x), exponential backoff, reconnecting UI
- Enriched /health endpoint: run_id, active_item, last_segment_seq, last_r2_pub, consecutive_failures, unhealthy detection
- Updated tests: HealthHandler (new fields + unhealthy), player error recovery test
- Updated TODO.md, BACKLOG.md, DONE.md, MEMORY.md

frontend/src/main.ts

@@ -18,6 +18,11 @@ let username = "viewer" + Math.floor(Math.random() * 1000);
 let chatVisible = true;
 const onlineUsers = new Set<string>();
 
+// Player error recovery state (STREAMING.md contract)
+let playerErrorCount = 0;
+const PLAYER_MAX_RETRIES = 5;
+const PLAYER_BASE_DELAY_MS = 2000;
+
 export function resetViewerStateForTests() {
   hls = null;
   ws = null;
@@ -25,6 +30,7 @@ export function resetViewerStateForTests() {
   username = "viewer";
   chatVisible = true;
   onlineUsers.clear();
+  playerErrorCount = 0;
 }
 
 export function resolveWebSocketBaseUrl() {
@@ -159,10 +165,60 @@ export async function initPlayerAndChat(loadHlsModule: () => Promise<{ default:
     try {
       const { default: Hls } = await loadHlsModule();
       if (Hls.isSupported()) {
-        hls = new Hls();
+        hls = new Hls({
+          liveDurationInfinity: true,
+          liveSyncDurationCount: 3,
+        });
         hls.loadSource(manifestUrl);
         hls.attachMedia(video);
         hls.on(Hls.Events.MANIFEST_PARSED, () => video.play());
+
+        // Player error recovery (STREAMING.md contract)
+        hls.on(Hls.Events.ERROR, (_event, data) => {
+          if (!data.fatal) return;
+
+          playerErrorCount++;
+
+          switch (data.type) {
+            case Hls.ErrorTypes.NETWORK_ERROR:
+              if (playerErrorCount <= PLAYER_MAX_RETRIES) {
+                const delay = PLAYER_BASE_DELAY_MS * Math.pow(2, playerErrorCount - 1);
+                console.warn(`HLS network error (attempt ${playerErrorCount}/${PLAYER_MAX_RETRIES}), retrying in ${delay}ms...`);
+                showReconnecting("Reconnecting...");
+                setTimeout(() => {
+                  hls?.startLoad();
+                }, delay);
+              } else {
+                console.error("HLS network error: max retries exhausted");
+                showReconnecting("Stream temporarily unavailable");
+              }
+              break;
+
+            case Hls.ErrorTypes.MEDIA_ERROR:
+              if (playerErrorCount <= 1) {
+                console.warn("HLS media error, attempting recovery...");
+                showReconnecting("Recovering...");
+                hls.recoverMediaError();
+              } else {
+                console.error("HLS media error: recovery failed");
+                hls.destroy();
+                showReconnecting("Stream temporarily unavailable");
+              }
+              break;
+
+            default:
+              console.error("HLS fatal error:", data.type, data.details);
+              hls.destroy();
+              showReconnecting("Stream temporarily unavailable");
+              break;
+          }
+        });
+
+        // Reset error count on successful manifest parse
+        hls.on(Hls.Events.MANIFEST_PARSED, () => {
+          playerErrorCount = 0;
+          hideReconnecting();
+        });
       }
     } catch (error) {
       console.error("Failed to load HLS player", error);
@@ -179,6 +235,24 @@ export async function initPlayerAndChat(loadHlsModule: () => Promise<{ default:
   console.log("Linear Void Frontend initialized - HLS Player + Chat Sidebar ready");
 }
 
+export function showReconnecting(message = "Reconnecting...") {
+  const overlay = document.getElementById("reconnecting-overlay");
+  const text = document.getElementById("reconnecting-text");
+  if (overlay) {
+    overlay.classList.remove("hidden");
+  }
+  if (text) {
+    text.textContent = message;
+  }
+}
+
+export function hideReconnecting() {
+  const overlay = document.getElementById("reconnecting-overlay");
+  if (overlay) {
+    overlay.classList.add("hidden");
+  }
+}
+
 function toggleChatPanel() {
   const shell = document.querySelector(".viewer-shell");
   const toggle = document.getElementById("chat-toggle");