[Bug]: Moving a project folder reports a Codex spawn failure instead of the missing folder, and the project cannot be re-linked

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Steps to reproduce

1. Add any project, like D:\t3code-repro\workspace\t3code and start a session in it and send any message.
2. Quit T3 Code. Move the folder to anywhere like D:\t3code-repro\workspace\tools\t3code.
3. Reopen T3 Code. The project is still listed and still shows its threads. The server logs no warning about the missing root at startup.
4. Open the thread and send another message.
5. Look for any way to point the project at its new location.
6. Add the folder from its new location instead.

Expected behavior

Step 4 should report that the workspace folder is missing, and name it. For example:

    This project's folder no longer exists:
    D:\t3code-repro\workspace\t3code

Step 5 should offer some way to re-link the project to its new path, keeping its threads.

Actual behavior

Step 4 shows a toast blaming the Codex binary and quoting a .ts source location, never mentioning the folder:

    ProviderAdapterProcessError: Provider adapter process error (codex) for thread 830169cc-...:
    Failed to spawn Codex App Server process for command: codex app-server
    at file:///.../apps/server/src/provider/Layers/CodexAdapter.ts:1441:15

The real reason is present in the error object, but only three [cause] levels down (full chain under Logs): NotFound: FileSystem.access (D:\t3code-repro\workspace\t3code). So the missing folder is detected and then discarded before it reaches the user.

Step 5 has no affordance at all: nothing in the project context menu, project settings, or command palette points a project at a new path.

Step 6 silently creates a second project with the same name, leaving the original threads in the first project, whose folder no longer exists. There is no way to move them across.

I dug into why the path is lost and why re-linking is impossible; posting that as a follow-up comment to keep this field readable.

Impact

Major degradation or frequent failure

Version or commit

6efcf3e10 (v0.0.32-nightly.20260730.954); also present in v0.0.31 stable

Environment

Windows 11, T3 Code dev build via pnpm dev, codex provider, Node 25.4.0

Logs or stack traces

ProviderAdapterProcessError: Provider adapter process error (codex) for thread 830169cc-6827-4bdb-ab7f-a8c351fbc60e: Failed to spawn Codex App Server process for command: codex app-server
    at file:///D:/t3code-repro/src/apps/server/src/provider/Layers/CodexAdapter.ts:1441:15
    at startSession (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:503:23)
    at startSession (definition) (file:///D:/t3code-repro/src/apps/server/src/provider/Layers/ProviderService.ts:522:70)
    at ensureSessionForThread (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:628:12)
    at ensureSessionForThread (definition) (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:360:41)
    at processTurnStartRequested (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:1064:16)
    at processTurnStartRequested (definition) (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:780:44)
    at processDomainEvent (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:1082:5)
    at processDomainEvent (definition) (file:///D:/t3code-repro/src/apps/server/src/orchestration/Layers/ProviderCommandReactor.ts:1038:37) {
  [cause]: CodexAppServerSpawnError: Failed to spawn Codex App Server process for command: codex app-server
      at file:///D:/t3code-repro/src/apps/server/src/provider/Layers/CodexSessionRuntime.ts:756:13 {
    [cause]: PlatformError: NotFound: FileSystem.access (D:\t3code-repro\workspace\t3code)
        at Module.systemError (.../effect/dist/PlatformError.js:144:39) {
      [cause]: Error: ENOENT: no such file or directory, access 'D:\t3code-repro\workspace\t3code'
    }
  }
}

Screenshots, recordings, or supporting files

firefox_mxPfdPVzP3.png

Workaround

None in-app. I recovered by editing ~/.t3/userdata/state.sqlite with the app closed, after backing it up with sqlite3 .backup:

BEGIN IMMEDIATE;

-- 1. Reparent the stranded thread into the project with the correct root.
--    Raw projection edit, because no event can move a thread between projects.
UPDATE projection_threads
   SET project_id = '<new-project-id>'
 WHERE thread_id  = '<stranded-thread-id>';

-- 2. Patch the historical thread.created payload so a projection replay reproduces the same state.
UPDATE orchestration_events
   SET payload_json = replace(payload_json, '<old-project-id>', '<new-project-id>')
 WHERE sequence = <sequence of that thread.created>;

-- 3. Append a real project.deleted event for the now-empty duplicate. Since
--    projection_state.last_applied_sequence sits below this row, the app applies it itself on the
--    next start, so no projection row needs hand-editing for this part.
INSERT INTO orchestration_events
  (event_id, aggregate_kind, stream_id, stream_version, event_type, occurred_at,
   command_id, causation_event_id, correlation_id, actor_kind, payload_json, metadata_json)
VALUES
  ('<uuid>', 'project', '<old-project-id>', 1, 'project.deleted', '<iso-ts>',
   NULL, NULL, NULL, 'client',
   '{"projectId":"<old-project-id>","deletedAt":"<iso-ts>"}', '{}');

COMMIT;

Related: #975, #1726, #1932 (misleading error, closed without the exact text now provided above), #2357 (relocate, closed not_planned), #2467 and #1614 (closed unmerged), #3829 (merged).

Start by tracing the error through apps/server/src/provider/Layers/CodexAdapter.ts:1441 and CodexSessionRuntime.ts:756, then follow project and thread handling in ProviderCommandReactor.ts. Reproduce the missing-folder case and inspect state.sqlite persistence. Done means the user sees the missing path and can relink the existing project without losing its threads.