fix(web-chat): prevent blank chat pane after assistant response

Carly 2.0 · claude · Carly 2.0 · commit 6efe3f1008fd · 2026-05-04T11:53:35.000-05:00
After a turn completes, the UI could briefly or permanently show blank content. Two related issues: 1. When loadChatHistory is triggered by a final event (tool turns or non-renderable final messages), chatLoading was only set inside the async function body — synchronously, but still after the void call site returned. In practice loadChatHistory sets it before the first await, but explicitly pre-setting chatLoading = true at every call site in handleTerminalChatEvent and handleChatGatewayEvent makes the loading state visible to any synchronous re-render that fires between the call and the function body running. 2. When loadChatHistory returned early because the client was disconnected (!state.client || !state.connected), any chatLoading = true that had been pre-set externally was never cleared, leaving the UI stuck in a loading state rather than showing cached messages. Together these close the window where: streaming ends → chatStream = null → chatMessages not yet updated → chatLoading still false → UI renders empty (isEmpty = true) before the history reload finishes. Fixes #67035 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
diff --git a/ui/src/ui/app-gateway.ts b/ui/src/ui/app-gateway.ts
@@ -593,7 +593,9 @@ function handleTerminalChatEvent(
   // replace the now-cleared streaming state.
   if (hadToolEvents && state === "final") {
     const completedRunId = runId ?? null;
-    void loadChatHistory(host as unknown as ChatState).finally(() => {
+    const chatStateHostForTools = host as unknown as ChatState;
+    chatStateHostForTools.chatLoading = true;
+    void loadChatHistory(chatStateHostForTools).finally(() => {
       if (completedRunId && host.chatRunId && host.chatRunId !== completedRunId) {
         return;
       }
@@ -658,11 +660,15 @@ function handleChatGatewayEvent(host: GatewayHost, payload: ChatEventPayload | u
     deferredReloadHost.pendingSessionMessageReloadSessionKey = null;
   }
   if (finalEventNeedsHistoryReload && !historyReloaded && !terminalEventIsForDifferentActiveRun) {
-    void loadChatHistory(host as unknown as ChatState);
+    const chatStateHost = host as unknown as ChatState;
+    chatStateHost.chatLoading = true;
+    void loadChatHistory(chatStateHost);
     return;
   }
   if (shouldReplayDeferredSessionMessageReload && !historyReloaded) {
-    void loadChatHistory(host as unknown as ChatState);
+    const chatStateHost = host as unknown as ChatState;
+    chatStateHost.chatLoading = true;
+    void loadChatHistory(chatStateHost);
   }
 }
 
diff --git a/ui/src/ui/controllers/chat.ts b/ui/src/ui/controllers/chat.ts
@@ -386,6 +386,7 @@ function maybeResetToolStream(state: ChatState) {
 
 export async function loadChatHistory(state: ChatState) {
   if (!state.client || !state.connected) {
+    state.chatLoading = false;
     return;
   }
   const sessionKey = state.sessionKey;

Original file line number	Diff line number	Diff line change
`@@ -593,7 +593,9 @@ function handleTerminalChatEvent(`
`593`	`593`	`// replace the now-cleared streaming state.`
`594`	`594`	`if (hadToolEvents && state === "final") {`
`595`	`595`	`const completedRunId = runId ?? null;`
`596`		`- void loadChatHistory(host as unknown as ChatState).finally(() => {`
	`596`	`+ const chatStateHostForTools = host as unknown as ChatState;`
	`597`	`+ chatStateHostForTools.chatLoading = true;`
	`598`	`+ void loadChatHistory(chatStateHostForTools).finally(() => {`
`597`	`599`	`if (completedRunId && host.chatRunId && host.chatRunId !== completedRunId) {`
`598`	`600`	`return;`
`599`	`601`	`}`
`@@ -658,11 +660,15 @@ function handleChatGatewayEvent(host: GatewayHost, payload: ChatEventPayload \| u`
`658`	`660`	`deferredReloadHost.pendingSessionMessageReloadSessionKey = null;`
`659`	`661`	`}`
`660`	`662`	`if (finalEventNeedsHistoryReload && !historyReloaded && !terminalEventIsForDifferentActiveRun) {`
`661`		`- void loadChatHistory(host as unknown as ChatState);`
	`663`	`+ const chatStateHost = host as unknown as ChatState;`
	`664`	`+ chatStateHost.chatLoading = true;`
	`665`	`+ void loadChatHistory(chatStateHost);`
`662`	`666`	`return;`
`663`	`667`	`}`
`664`	`668`	`if (shouldReplayDeferredSessionMessageReload && !historyReloaded) {`
`665`		`- void loadChatHistory(host as unknown as ChatState);`
	`669`	`+ const chatStateHost = host as unknown as ChatState;`
	`670`	`+ chatStateHost.chatLoading = true;`
	`671`	`+ void loadChatHistory(chatStateHost);`
`666`	`672`	`}`
`667`	`673`	`}`
`668`	`674`
Original file line number	Diff line number	Diff line change
`@@ -386,6 +386,7 @@ function maybeResetToolStream(state: ChatState) {`
`386`	`386`
`387`	`387`	`export async function loadChatHistory(state: ChatState) {`
`388`	`388`	`if (!state.client \|\| !state.connected) {`
	`389`	`+ state.chatLoading = false;`
`389`	`390`	`return;`
`390`	`391`	`}`
`391`	`392`	`const sessionKey = state.sessionKey;`