Restore archived agents from History (#2316)

* fix(app): restore archived agents from History

History navigation lost the explicit archived-agent intent during tab reconciliation, and workspace recovery stopped after restoring the workspace. Preserve the selected tab and recover its provider session as one action while serializing provider resume with timeline hydration.

* fix(app): preserve archived agent recovery invariants

* fix(server): preserve timeline hydration call shape

* fix(app): retain agent tabs through lookup

* fix(server): upgrade in-flight timeline broadcast

packages/app/src/panels/agent-panel.tsx

@@ -341,13 +341,14 @@ function useAgentPanelDescriptor(
 }
 
 function AgentPanel() {
-  const { serverId, target, openFileInWorkspace } = usePaneContext();
+  const { serverId, workspaceId, target, openFileInWorkspace } = usePaneContext();
   const { isInteractive } = usePaneFocus();
   invariant(target.kind === "agent", "AgentPanel requires agent target");
 
   return (
     <AgentPanelContent
       serverId={serverId}
+      workspaceId={workspaceId}
       agentId={target.agentId}
       isPaneFocused={isInteractive}
       onOpenWorkspaceFile={openFileInWorkspace}
@@ -481,11 +482,13 @@ type AgentLookupState =
 
 function AgentPanelContent({
   serverId,
+  workspaceId,
   agentId,
   isPaneFocused,
   onOpenWorkspaceFile,
 }: {
   serverId: string;
+  workspaceId: string;
   agentId: string;
   isPaneFocused: boolean;
   onOpenWorkspaceFile?: (request: WorkspaceFileOpenRequest) => void;
@@ -535,6 +538,7 @@ function AgentPanelContent({
   return (
     <AgentPanelBody
       serverId={resolvedServerId}
+      workspaceId={workspaceId}
       agentId={resolvedAgentId}
       isPaneFocused={isPaneFocused}
       client={runtimeClient}
@@ -547,6 +551,7 @@ function AgentPanelContent({
 
 function AgentPanelBody({
   serverId,
+  workspaceId,
   agentId,
   isPaneFocused,
   client,
@@ -555,6 +560,7 @@ function AgentPanelBody({
   onOpenWorkspaceFile,
 }: {
   serverId: string;
+  workspaceId: string;
   agentId?: string;
   isPaneFocused: boolean;
   client: ReturnType<typeof useHostRuntimeClient>;
@@ -585,6 +591,8 @@ function AgentPanelBody({
   );
   const [lookupState, setLookupState] = useState<AgentLookupState>({ tag: "idle" });
   const lookupAttemptTokenRef = useRef(0);
+  const workspaceKey = buildWorkspaceTabPersistenceKey({ serverId, workspaceId });
+  const resolvePendingAgent = useWorkspaceLayoutStore((state) => state.resolvePendingAgent);
 
   useEffect(() => {
     lookupAttemptTokenRef.current += 1;
@@ -596,6 +604,9 @@ function AgentPanelBody({
       return;
     }
     if (agentState.id) {
+      if (workspaceKey) {
+        resolvePendingAgent(workspaceKey, agentId);
+      }
       if (lookupState.tag !== "idle") {
         setLookupState({ tag: "idle" });
       }
@@ -618,6 +629,9 @@ function AgentPanelBody({
           return;
         }
         if (!result) {
+          if (workspaceKey) {
+            resolvePendingAgent(workspaceKey, agentId);
+          }
           setLookupState({
             tag: "not_found",
             message: `Agent not found: ${agentId}`,
@@ -626,6 +640,9 @@ function AgentPanelBody({
         }
 
         storeFetchedAgentDetail({ serverId, result });
+        if (workspaceKey) {
+          resolvePendingAgent(workspaceKey, agentId);
+        }
         setLookupState({ tag: "idle" });
         return;
       })
@@ -635,12 +652,25 @@ function AgentPanelBody({
         }
         const message = toErrorMessage(error);
         if (isNotFoundErrorMessage(message)) {
+          if (workspaceKey) {
+            resolvePendingAgent(workspaceKey, agentId);
+          }
           setLookupState({ tag: "not_found", message });
           return;
         }
         setLookupState({ tag: "error", message });
       });
-  }, [agentId, agentState.id, client, hasSession, isConnected, lookupState.tag, serverId]);
+  }, [
+    agentId,
+    agentState.id,
+    client,
+    hasSession,
+    isConnected,
+    lookupState.tag,
+    resolvePendingAgent,
+    serverId,
+    workspaceKey,
+  ]);
 
   if (lookupState.tag === "not_found") {
     return (
@@ -894,6 +924,7 @@ function ChatAgentContent({
     routeKey: `${serverId}:${agentId ?? ""}`,
     input: {
       agent: agent ?? null,
+      isArchived: agentState.archivedAt !== null,
       missingAgentState,
       isConnected,
       isArchivingCurrentAgent,
@@ -947,6 +978,9 @@ function ChatAgentContent({
     if (!agentId) {
       return;
     }
+    if (agentState.archivedAt) {
+      return;
+    }
     if (agentState.id && hasAppliedAuthoritativeHistory) {
       if (
         missingAgentState.kind === "resolving" ||
@@ -1012,6 +1046,7 @@ function ChatAgentContent({
       });
   }, [
     agentState.id,
+    agentState.archivedAt,
     hasAppliedAuthoritativeHistory,
     agentId,
     client,