[Codex app] Opening existing local conversations stalls 10–45s in thread/resume

Environment

• ChatGPT / Codex app: 26.707.31428 (build 5059)
• Codex app-server: 0.144.0-alpha.4
• macOS: 27.0 (26A5353q)
• App session ID: 2a267adc-b3ca-4f5c-90c6-1f9f09567c2e

Description

Opening an existing local conversation frequently shows a blank view for 10–45 seconds before the content appears. The delay is reproducible after fully restarting the app and also affects very small conversations.

I archived four unusually large old session files, reducing the active sessions directory from 556 MB to 174 MB, but the problem still occurs on a 220 KB conversation with only two turns.

Steps to reproduce

1. Launch the Codex desktop experience.
2. Open an existing local conversation from the sidebar.
3. Observe that the conversation view remains blank while the thread is being resumed.
4. Wait 10–45 seconds for the content to appear.

Expected behavior

The locally stored conversation should render immediately after thread/read completes.

Actual behavior and diagnostics

Affected conversation ID:

019f49a5-4401-7260-8497-1b55a72daa78

Latest reproduction on 2026-07-10:

• maybe_resume_started: 07:35:05.298Z
• thread/read: 4 ms
• plugin/list: 17–18 ms
• thread/resume: 13,273 ms
• maybe_resume_success: 07:35:18.626Z
• About 19 ResizeObserver loop completed with undelivered notifications errors immediately followed.

The same conversation previously took 28,260 ms and 45,166 ms in thread/resume.

The Browser backend became ready in approximately 6 ms, and no MCP initialization delay occurred during the latest reproduction. Background /wham/usage and /wham/tasks/list requests returned 401 with willRetry=false; the 401 occurred after the resume completed, so it does not appear to be the blocking operation.

No renderer crash or app-server disconnection was logged.

Relevant local app logs are under:

~/Library/Logs/com.openai.codex/2026/07/10/

I have not attached the full log because it may contain local paths or other sensitive context, but I can provide a sanitized excerpt if needed.