refactor: isolate chat hot paths and lazy server watchers

Split static history from live tail, stabilize chat data identities, and reduce scroll-shell churn so old viewport content stops waking on stream deltas. Also defer watcher startup and health polling so idle runtime work better matches actual usage.

packages/web/server/index.js

@@ -339,6 +339,7 @@ let isExternalOpenCode = false;
 let exitOnShutdown = true;
 let uiAuthController = null;
 let activeTunnelController = null;
+let globalWatcherStartPromise = null;
 const tunnelProviderRegistry = createTunnelProviderRegistry([
   createCloudflareTunnelProvider(),
 ]);
@@ -739,13 +740,24 @@ const waitForOpenCodeReady = (...args) => openCodeLifecycleRuntime.waitForOpenCo
 const waitForAgentPresence = (...args) => openCodeLifecycleRuntime.waitForAgentPresence(...args);
 const refreshOpenCodeAfterConfigChange = (...args) => openCodeLifecycleRuntime.refreshOpenCodeAfterConfigChange(...args);
 const startHealthMonitoring = () => openCodeLifecycleRuntime.startHealthMonitoring(HEALTH_CHECK_INTERVAL);
+const ensureGlobalWatcherStarted = async () => {
+  if (globalWatcherStartPromise) {
+    return globalWatcherStartPromise;
+  }
+
+  globalWatcherStartPromise = openCodeWatcherRuntime.start().catch((error) => {
+    globalWatcherStartPromise = null;
+    throw error;
+  });
+
+  return globalWatcherStartPromise;
+};
 const bootstrapOpenCodeAtStartup = async (...args) => {
   await openCodeLifecycleRuntime.bootstrapOpenCodeAtStartup(...args);
   scheduleOpenCodeApiDetection();
-  startHealthMonitoring();
-  void openCodeWatcherRuntime.start().catch((error) => {
-    console.warn(`Global event watcher startup failed: ${error?.message || error}`);
-  });
+  if (openCodeLifecycleState.openCodeProcess && !openCodeLifecycleState.isExternalOpenCode) {
+    startHealthMonitoring();
+  }
 };
 const killProcessOnPort = (...args) => openCodeLifecycleRuntime.killProcessOnPort(...args);
 
@@ -871,6 +883,7 @@ async function main(options = {}) {
     resolveZenModel,
     sayTTSCapability,
     ensurePushInitialized,
+    ensureGlobalWatcherStarted,
     getOrCreateVapidKeys,
     getUiSessionTokenFromRequest,
     writeSettingsToDisk,

packages/web/server/lib/notifications/routes.js

@@ -26,6 +26,7 @@ export const registerNotificationRoutes = (app, dependencies) => {
   const {
     uiAuthController,
     ensurePushInitialized,
+    ensureGlobalWatcherStarted,
     getOrCreateVapidKeys,
     getUiSessionTokenFromRequest,
     readSettingsFromDiskMigrated,
@@ -45,6 +46,17 @@ export const registerNotificationRoutes = (app, dependencies) => {
     setPushInitialized,
   } = dependencies;
 
+  const ensureSessionWatcher = async () => {
+    if (typeof ensureGlobalWatcherStarted !== 'function') {
+      return;
+    }
+    try {
+      await ensureGlobalWatcherStarted();
+    } catch (error) {
+      console.warn('[OpenCodeWatcher] lazy start failed:', error?.message ?? error);
+    }
+  };
+
   app.get('/api/push/vapid-public-key', async (_req, res) => {
     try {
       await ensurePushInitialized();
@@ -58,6 +70,7 @@ export const registerNotificationRoutes = (app, dependencies) => {
 
   app.post('/api/push/subscribe', async (req, res) => {
     await ensurePushInitialized();
+    await ensureSessionWatcher();
 
     const uiToken = uiAuthController?.ensureSessionToken
       ? await uiAuthController.ensureSessionToken(req, res)
@@ -146,10 +159,12 @@ export const registerNotificationRoutes = (app, dependencies) => {
   });
 
   app.get('/api/session-activity', (_req, res) => {
+    void ensureSessionWatcher();
     res.json(getSessionActivitySnapshot());
   });
 
-  app.get('/api/sessions/snapshot', (_req, res) => {
+  app.get('/api/sessions/snapshot', async (_req, res) => {
+    await ensureSessionWatcher();
     res.json({
       statusSessions: getSessionStateSnapshot(),
       attentionSessions: getSessionAttentionSnapshot(),
@@ -157,7 +172,8 @@ export const registerNotificationRoutes = (app, dependencies) => {
     });
   });
 
-  app.get('/api/sessions/status', (_req, res) => {
+  app.get('/api/sessions/status', async (_req, res) => {
+    await ensureSessionWatcher();
     const snapshot = getSessionStateSnapshot();
     res.json({
       sessions: snapshot,
@@ -165,7 +181,8 @@ export const registerNotificationRoutes = (app, dependencies) => {
     });
   });
 
-  app.get('/api/sessions/:id/status', (req, res) => {
+  app.get('/api/sessions/:id/status', async (req, res) => {
+    await ensureSessionWatcher();
     const sessionId = req.params.id;
     const state = getSessionState(sessionId);
 
@@ -182,7 +199,8 @@ export const registerNotificationRoutes = (app, dependencies) => {
     });
   });
 
-  app.get('/api/sessions/attention', (_req, res) => {
+  app.get('/api/sessions/attention', async (_req, res) => {
+    await ensureSessionWatcher();
     const snapshot = getSessionAttentionSnapshot();
     res.json({
       sessions: snapshot,
@@ -190,7 +208,8 @@ export const registerNotificationRoutes = (app, dependencies) => {
     });
   });
 
-  app.get('/api/sessions/:id/attention', (req, res) => {
+  app.get('/api/sessions/:id/attention', async (req, res) => {
+    await ensureSessionWatcher();
     const sessionId = req.params.id;
     const state = getSessionAttentionState(sessionId);
 

packages/web/server/lib/opencode/bootstrap-runtime.js

@@ -25,6 +25,7 @@ export const createBootstrapRuntime = (dependencies) => {
       resolveZenModel,
       sayTTSCapability,
       ensurePushInitialized,
+      ensureGlobalWatcherStarted,
       getOrCreateVapidKeys,
       getUiSessionTokenFromRequest,
       writeSettingsToDisk,
@@ -74,6 +75,7 @@ export const createBootstrapRuntime = (dependencies) => {
     registerNotificationRoutes(app, {
       uiAuthController,
       ensurePushInitialized,
+      ensureGlobalWatcherStarted,
       getOrCreateVapidKeys,
       getUiSessionTokenFromRequest,
       readSettingsFromDiskMigrated,