fix: show clear error when project directory is missing

.gitignore

@@ -16,3 +16,4 @@ release/
 apps/web/.playwright
 apps/web/playwright-report
 apps/web/src/components/__screenshots__
+.worktrees/

apps/server/src/codexAppServerManager.ts

@@ -1,6 +1,7 @@
 import { type ChildProcessWithoutNullStreams, spawn, spawnSync } from "node:child_process";
 import { randomUUID } from "node:crypto";
 import { EventEmitter } from "node:events";
+import { existsSync } from "node:fs";
 import readline from "node:readline";
 
 import {
@@ -1546,6 +1547,12 @@ function assertSupportedCodexCliVersion(input: {
       lower.includes("command not found") ||
       lower.includes("not found")
     ) {
+      // Disambiguate: is the cwd missing, or is the binary missing?
+      if (!existsSync(input.cwd)) {
+        throw new Error(
+          `Project directory does not exist: ${input.cwd}. The folder may have been moved or deleted.`,
+        );
+      }
       throw new Error(`Codex CLI (${input.binaryPath}) is not installed or not executable.`);
     }
     throw new Error(

apps/server/src/wsServer.ts

@@ -776,6 +776,18 @@ export const createServer = Effect.fn(function* (): Effect.fn.Return<
         return { relativePath: target.relativePath };
       }
 
+      case WS_METHODS.checkProjectDirectories: {
+        const { cwds } = request.body;
+        const results = yield* Effect.forEach(cwds, (cwd) =>
+          fileSystem.stat(cwd).pipe(
+            Effect.map((stat) => (stat.type !== "Directory" ? cwd : null)),
+            Effect.catch(() => Effect.succeed(cwd)),
+          ),
+          { concurrency: "unbounded" },
+        );
+        return { missing: results.filter((r): r is string => r !== null) };
+      }
+
       case WS_METHODS.shellOpenInEditor: {
         const body = stripRequestTag(request.body);
         return yield* openInEditor(body);

apps/web/src/components/ChatView.tsx

@@ -765,6 +765,11 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const latestTurnSettled = isLatestTurnSettled(activeLatestTurn, activeThread?.session ?? null);
   const activeProject = projects.find((p) => p.id === activeThread?.projectId);
 
+  const missingProjectCwds = useStore((s) => s.missingProjectCwds);
+  const isProjectDirectoryMissing = activeProject
+    ? missingProjectCwds.has(activeProject.cwd)
+    : false;
+
   const openPullRequestDialog = useCallback(
     (reference?: string) => {
       if (!canCheckoutPullRequestIntoThread) {
@@ -2552,7 +2557,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const onSend = async (e?: { preventDefault: () => void }) => {
     e?.preventDefault();
     const api = readNativeApi();
-    if (!api || !activeThread || isSendBusy || isConnecting || sendInFlightRef.current) return;
+    if (!api || !activeThread || isSendBusy || isConnecting || isProjectDirectoryMissing || sendInFlightRef.current) return;
     if (activePendingProgress) {
       onAdvanceActivePendingUserInput();
       return;
@@ -3578,8 +3583,14 @@ export default function ChatView({ threadId }: ChatViewProps) {
       {/* Error banner */}
       <ProviderHealthBanner status={activeProviderStatus} />
       <ThreadErrorBanner
-        error={activeThread.error}
-        onDismiss={() => setThreadError(activeThread.id, null)}
+        error={
+          isProjectDirectoryMissing
+            ? `Project directory does not exist: ${activeProject?.cwd ?? "unknown"}. The folder may have been moved or deleted.`
+            : activeThread.error
+        }
+        {...(isProjectDirectoryMissing
+          ? {}
+          : { onDismiss: () => setThreadError(activeThread.id, null) })}
       />
       {/* Main content area with optional plan sidebar */}
       <div className="flex min-h-0 min-w-0 flex-1">
@@ -3773,18 +3784,20 @@ export default function ChatView({ threadId }: ChatViewProps) {
                     onCommandKeyDown={onComposerCommandKey}
                     onPaste={onComposerPaste}
                     placeholder={
-                      isComposerApprovalState
-                        ? (activePendingApproval?.detail ??
-                          "Resolve this approval request to continue")
-                        : activePendingProgress
+                      isProjectDirectoryMissing
+                        ? "Project directory is missing. Restore the folder to continue."
+                        : isComposerApprovalState
+                          ? (activePendingApproval?.detail ??
+                            "Resolve this approval request to continue")
+                          : activePendingProgress
                           ? "Type your own answer, or leave this blank to use the selected option"
                           : showPlanFollowUpPrompt && activeProposedPlan
                             ? "Add feedback to refine the plan, or leave this blank to implement it"
                             : phase === "disconnected"
                               ? "Ask for follow-up changes or attach images"
                               : "Ask anything, @tag files/folders, or use / to show available commands"
                     }
-                    disabled={isConnecting || isComposerApprovalState}
+                    disabled={isConnecting || isComposerApprovalState || isProjectDirectoryMissing}
                   />
                 </div>
 

apps/web/src/components/Sidebar.tsx

@@ -40,7 +40,7 @@ import { useLocation, useNavigate, useParams } from "@tanstack/react-router";
 import { useAppSettings } from "../appSettings";
 import { isElectron } from "../env";
 import { APP_STAGE_LABEL, APP_VERSION } from "../branding";
-import { isMacPlatform, newCommandId, newProjectId, newThreadId } from "../lib/utils";
+import { cn, isMacPlatform, newCommandId, newProjectId, newThreadId } from "../lib/utils";
 import { useStore } from "../store";
 import { isChatNewLocalShortcut, isChatNewShortcut, shortcutLabelForCommand } from "../keybindings";
 import { derivePendingApprovals, derivePendingUserInputs } from "../session-logic";
@@ -265,6 +265,7 @@ export default function Sidebar() {
   const getDraftThread = useComposerDraftStore((store) => store.getDraftThread);
   const terminalStateByThreadId = useTerminalStateStore((state) => state.terminalStateByThreadId);
   const clearTerminalState = useTerminalStateStore((state) => state.clearTerminalState);
+  const missingProjectCwds = useStore((store) => store.missingProjectCwds);
   const setProjectDraftThreadId = useComposerDraftStore((store) => store.setProjectDraftThreadId);
   const setDraftThreadContext = useComposerDraftStore((store) => store.setDraftThreadContext);
   const clearProjectDraftThreadId = useComposerDraftStore(
@@ -1520,6 +1521,8 @@ export default function Sidebar() {
                                   selectThreadTerminalState(terminalStateByThreadId, thread.id)
                                     .runningTerminalIds,
                                 );
+                                const projectCwd = projectCwdById.get(thread.projectId);
+                                const isProjectMissing = projectCwd ? missingProjectCwds.has(projectCwd) : false;
 
                                 return (
                                   <SidebarMenuSubItem
@@ -1654,7 +1657,12 @@ export default function Sidebar() {
                                             onClick={(e) => e.stopPropagation()}
                                           />
                                         ) : (
-                                          <span className="min-w-0 flex-1 truncate text-xs">
+                                          <span
+                                            className={cn(
+                                              "min-w-0 flex-1 truncate text-xs",
+                                              isProjectMissing && "line-through text-destructive/60",
+                                            )}
+                                          >
                                             {thread.title}
                                           </span>
                                         )}

apps/web/src/hooks/useProjectDirectoryCheck.ts

@@ -0,0 +1,50 @@
+import { useCallback, useEffect, useRef } from "react";
+import { WS_METHODS } from "@t3tools/contracts";
+import { useShallow } from "zustand/react/shallow";
+import { readNativeApi } from "../nativeApi";
+import { useStore } from "../store";
+
+const CHECK_DEBOUNCE_MS = 500;
+const EMPTY_SET: ReadonlySet<string> = new Set();
+
+export function useProjectDirectoryCheck(): void {
+  const projectCwds = useStore(
+    useShallow((s) => s.projects.map((p) => p.cwd)),
+  );
+  const setMissingProjectCwds = useStore((s) => s.setMissingProjectCwds);
+  const debounceRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  const checkDirectories = useCallback(async () => {
+    const api = readNativeApi();
+    if (!api || projectCwds.length === 0) return;
+
+    try {
+      const result = await api.request(WS_METHODS.checkProjectDirectories, { cwds: projectCwds });
+      const missing: string[] = (result as { missing: string[] }).missing ?? [];
+      setMissingProjectCwds(missing.length === 0 ? EMPTY_SET : new Set(missing));
+    } catch {
+      // If the check itself fails, don't block the UI
+    }
+  }, [projectCwds, setMissingProjectCwds]);
+
+  // Check on mount and when projects change
+  useEffect(() => {
+    void checkDirectories();
+  }, [checkDirectories]);
+
+  // Check on window focus (debounced)
+  useEffect(() => {
+    const onFocus = () => {
+      if (debounceRef.current) clearTimeout(debounceRef.current);
+      debounceRef.current = setTimeout(() => {
+        void checkDirectories();
+      }, CHECK_DEBOUNCE_MS);
+    };
+
+    window.addEventListener("focus", onFocus);
+    return () => {
+      window.removeEventListener("focus", onFocus);
+      if (debounceRef.current) clearTimeout(debounceRef.current);
+    };
+  }, [checkDirectories]);
+}

apps/web/src/routes/__root.tsx

@@ -18,6 +18,7 @@ import { readNativeApi } from "../nativeApi";
 import { clearPromotedDraftThreads, useComposerDraftStore } from "../composerDraftStore";
 import { useStore } from "../store";
 import { useTerminalStateStore } from "../terminalStateStore";
+import { useProjectDirectoryCheck } from "../hooks/useProjectDirectoryCheck";
 import { preferredTerminalEditor } from "../terminal-links";
 import { terminalRunningSubprocessFromEvent } from "../terminalActivity";
 import { onServerConfigUpdated, onServerWelcome } from "../wsNativeApi";
@@ -52,6 +53,7 @@ function RootRouteView() {
     <ToastProvider>
       <AnchoredToastProvider>
         <EventRouter />
+        <ProjectDirectoryChecker />
         <DesktopProjectBootstrap />
         <Outlet />
       </AnchoredToastProvider>
@@ -317,6 +319,11 @@ function EventRouter() {
   return null;
 }
 
+function ProjectDirectoryChecker() {
+  useProjectDirectoryCheck();
+  return null;
+}
+
 function DesktopProjectBootstrap() {
   // Desktop hydration runs through EventRouter project + orchestration sync.
   return null;

apps/web/src/store.test.ts

@@ -47,6 +47,7 @@ function makeState(thread: Thread): AppState {
     ],
     threads: [thread],
     threadsHydrated: true,
+    missingProjectCwds: new Set(),
   };
 }
 
@@ -182,6 +183,7 @@ describe("store pure functions", () => {
       ],
       threads: [],
       threadsHydrated: true,
+      missingProjectCwds: new Set(),
     };
 
     const next = reorderProjects(state, project1, project3);
@@ -229,6 +231,7 @@ describe("store read model sync", () => {
       ],
       threads: [],
       threadsHydrated: true,
+      missingProjectCwds: new Set(),
     };
     const readModel: OrchestrationReadModel = {
       snapshotSequence: 2,

apps/web/src/store.ts

@@ -22,6 +22,7 @@ export interface AppState {
   projects: Project[];
   threads: Thread[];
   threadsHydrated: boolean;
+  missingProjectCwds: ReadonlySet<string>;
 }
 
 const PERSISTED_STATE_KEY = "t3code:renderer-state:v8";
@@ -41,6 +42,7 @@ const initialState: AppState = {
   projects: [],
   threads: [],
   threadsHydrated: false,
+  missingProjectCwds: new Set(),
 };
 const persistedExpandedProjectCwds = new Set<string>();
 const persistedProjectOrderCwds: string[] = [];
@@ -441,9 +443,10 @@ interface AppStore extends AppState {
   reorderProjects: (draggedProjectId: Project["id"], targetProjectId: Project["id"]) => void;
   setError: (threadId: ThreadId, error: string | null) => void;
   setThreadBranch: (threadId: ThreadId, branch: string | null, worktreePath: string | null) => void;
+  setMissingProjectCwds: (cwds: ReadonlySet<string>) => void;
 }
 
-export const useStore = create<AppStore>((set) => ({
+export const useStore = create<AppStore>((set, get) => ({
   ...readPersistedState(),
   syncServerReadModel: (readModel) => set((state) => syncServerReadModel(state, readModel)),
   markThreadVisited: (threadId, visitedAt) =>
@@ -457,6 +460,14 @@ export const useStore = create<AppStore>((set) => ({
   setError: (threadId, error) => set((state) => setError(state, threadId, error)),
   setThreadBranch: (threadId, branch, worktreePath) =>
     set((state) => setThreadBranch(state, threadId, branch, worktreePath)),
+  setMissingProjectCwds: (cwds) => {
+    const current = get().missingProjectCwds;
+    if (cwds.size !== current.size) { set({ missingProjectCwds: cwds }); return; }
+    for (const c of cwds) {
+      if (!current.has(c)) { set({ missingProjectCwds: cwds }); return; }
+    }
+    // Sets are equal, no update needed
+  },
 }));
 
 // Persist state changes with debouncing to avoid localStorage thrashing

apps/web/src/wsNativeApi.ts

@@ -175,6 +175,8 @@ export function createWsNativeApi(): NativeApi {
           callback(message.data),
         ),
     },
+    request: <T = unknown>(method: string, params?: unknown) =>
+      transport.request<T>(method, params),
   };
 
   instance = { api, transport };

packages/contracts/src/ipc.ts

@@ -170,4 +170,6 @@ export interface NativeApi {
     replayEvents: (fromSequenceExclusive: number) => Promise<OrchestrationEvent[]>;
     onDomainEvent: (callback: (event: OrchestrationEvent) => void) => () => void;
   };
+  /** Low-level RPC call for methods without dedicated typed wrappers. */
+  request: <T = unknown>(method: string, params?: unknown) => Promise<T>;
 }

packages/contracts/src/ws.ts

@@ -47,6 +47,7 @@ export const WS_METHODS = {
   projectsRemove: "projects.remove",
   projectsSearchEntries: "projects.searchEntries",
   projectsWriteFile: "projects.writeFile",
+  checkProjectDirectories: "projects.checkDirectories",
 
   // Shell methods
   shellOpenInEditor: "shell.openInEditor",
@@ -111,6 +112,9 @@ const WebSocketRequestBody = Schema.Union([
   // Project Search
   tagRequestBody(WS_METHODS.projectsSearchEntries, ProjectSearchEntriesInput),
   tagRequestBody(WS_METHODS.projectsWriteFile, ProjectWriteFileInput),
+  tagRequestBody(WS_METHODS.checkProjectDirectories, Schema.Struct({
+    cwds: Schema.Array(Schema.String),
+  })),
 
   // Shell methods
   tagRequestBody(WS_METHODS.shellOpenInEditor, OpenInEditorInput),