feat(chat): add pending assistant response indicator

- detect when last message is from user and response is pending
- show "Starting..." indicator while awaiting assistant response
- include pending state in overall isWorking condition
- simplify hasServerAcknowledgedLocalDispatch to check only completedAt

Author: tyulyukov

apps/web/src/components/ChatView.logic.ts

@@ -350,12 +350,13 @@ export function hasServerAcknowledgedLocalDispatch(input: {
   }
 
   const latestTurn = input.latestTurn ?? null;
-
+  const latestTurnCompletedAt = latestTurn?.completedAt ?? null;
+  if (latestTurnCompletedAt === null) {
+    return false;
+  }
   return (
     input.localDispatch.latestTurnTurnId !== (latestTurn?.turnId ?? null) ||
-    input.localDispatch.latestTurnRequestedAt !== (latestTurn?.requestedAt ?? null) ||
-    input.localDispatch.latestTurnStartedAt !== (latestTurn?.startedAt ?? null) ||
-    input.localDispatch.latestTurnCompletedAt !== (latestTurn?.completedAt ?? null)
+    input.localDispatch.latestTurnCompletedAt !== latestTurnCompletedAt
   );
 }
 

apps/web/src/components/ChatView.tsx

@@ -1396,21 +1396,28 @@ export default function ChatView({ threadId, environmentId: environmentIdProp }:
   });
   const hasInFlightTurn = Boolean(activeLatestTurn && !activeLatestTurn.completedAt);
   const isSessionStarting = activeThread?.session?.orchestrationStatus === "starting";
+  const lastActiveMessage = activeThread?.messages[activeThread.messages.length - 1];
+  const hasPendingAssistantResponse = Boolean(
+    lastActiveMessage?.role === "user" &&
+    (!activeLatestTurn || Boolean(activeLatestTurn.completedAt)),
+  );
   const isWorking =
     phase === "running" ||
     isSendBusy ||
     isConnecting ||
     isRevertingCheckpoint ||
     hasInFlightTurn ||
-    isSessionStarting;
+    isSessionStarting ||
+    hasPendingAssistantResponse;
   const isCompacting = activeThread?.session?.compacting === true;
   const isThreadHydrating = activeThread !== undefined && !isThreadHydrated(activeThread);
   const nowIso = new Date(nowTick).toISOString();
-  const activeWorkStartedAt = deriveActiveWorkStartedAt(
-    activeLatestTurn,
-    activeThread?.session ?? null,
-    localDispatchStartedAt,
-  );
+  const activeWorkStartedAt =
+    deriveActiveWorkStartedAt(
+      activeLatestTurn,
+      activeThread?.session ?? null,
+      localDispatchStartedAt,
+    ) ?? (hasPendingAssistantResponse ? (lastActiveMessage?.createdAt ?? null) : null);
   const isComposerApprovalState = activePendingApproval !== null;
   const hasComposerHeader =
     isComposerApprovalState ||
@@ -4870,6 +4877,7 @@ export default function ChatView({ threadId, environmentId: environmentIdProp }:
                 workspaceRoot={activeWorkspaceRoot}
                 isSendBusy={isSendBusy}
                 isSessionStarting={isSessionStarting}
+                hasPendingAssistantResponse={hasPendingAssistantResponse}
                 isPreparingWorktree={isPreparingWorktree}
                 isCompacting={isCompacting}
                 onSubagentSelect={onSubagentSelect}

apps/web/src/components/chat/MessagesTimeline.test.tsx

@@ -102,6 +102,7 @@ describe("MessagesTimeline", () => {
         workspaceRoot={undefined}
         isSendBusy={false}
         isSessionStarting={false}
+        hasPendingAssistantResponse={false}
         isPreparingWorktree={false}
         isCompacting={false}
         onSubagentSelect={() => {}}
@@ -167,6 +168,7 @@ describe("MessagesTimeline", () => {
         workspaceRoot={undefined}
         isSendBusy={false}
         isSessionStarting={false}
+        hasPendingAssistantResponse={false}
         isPreparingWorktree={false}
         isCompacting={false}
         onSubagentSelect={() => {}}

apps/web/src/components/chat/MessagesTimeline.tsx

@@ -154,6 +154,7 @@ interface MessagesTimelineProps {
   workspaceRoot: string | undefined;
   isSendBusy: boolean;
   isSessionStarting: boolean;
+  hasPendingAssistantResponse: boolean;
   isPreparingWorktree: boolean;
   isCompacting: boolean;
   onSubagentSelect: (taskId: string) => void;
@@ -211,6 +212,7 @@ export const MessagesTimeline = memo(function MessagesTimeline({
   workspaceRoot,
   isSendBusy,
   isSessionStarting,
+  hasPendingAssistantResponse,
   isPreparingWorktree,
   isCompacting,
   onSubagentSelect,
@@ -619,7 +621,7 @@ export const MessagesTimeline = memo(function MessagesTimeline({
           <span className="shiny-text pt-1 text-xs font-semibold text-primary/60">
             {isPreparingWorktree
               ? "Preparing worktree\u2026"
-              : isSendBusy || isSessionStarting
+              : isSendBusy || isSessionStarting || hasPendingAssistantResponse
                 ? "Starting\u2026"
                 : isCompacting
                   ? "Compacting\u2026"