Codex Desktop: gpt-5.5 xhigh turn stalled 30m before first output, then resumed normally

[MisterRound]

Summary

A Codex Desktop turn using gpt-5.5 with xhigh reasoning remained user-visible as Thinking for more than 30 minutes before the first persisted assistant/reasoning item appeared. Once the first item appeared, the turn continued normally with assistant text and tool calls within seconds.

This looks different from ordinary slow generation: the local rollout has no assistant/reasoning/tool event during the gap, and normal persisted logs did not retain a useful stream/retry diagnostic for the missing interval.

Environment

• Product: Codex Desktop on Windows 11 with WSL2 Ubuntu workspace
• Desktop package observed in logs: OpenAI.Codex_26.519.5221.0
• Desktop release string observed in logs: 26.519.41501
• WSL app-server binary: codex-cli 0.130.0-alpha.5
• Model: gpt-5.5
• Reasoning effort: xhigh
• Workspace type: WSL project

Primary observed case

All timestamps below are UTC.

• User submitted turn: 2026-05-23T16:09:18.281Z
• First persisted assistant/reasoning item: 2026-05-23T16:39:56.682Z
• Pre-first-output gap: about 30m38s

First persisted output sequence after the stall:

2026-05-23T16:39:56.682Z response_item reasoning
2026-05-23T16:39:57.612Z event_msg agent_message
2026-05-23T16:39:57.612Z response_item message assistant
2026-05-23T16:40:08.580Z response_item function_call
2026-05-23T16:40:08.726Z response_item function_call_output
2026-05-23T16:40:08.727Z event_msg token_count

User-visible behavior: the thread sat on Thinking for the entire gap. When it finally resumed, it did not appear to replay a backlog; it just began producing the first reasoning/message/tool items at normal cadence.

Secondary same-day signal

In another thread on the same Desktop session, the UI visibly showed Reconnecting... 2/5 while still in Thinking on gpt-5.5/xhigh. That shorter case had about a 41.6s gap before first reasoning output, but the local Desktop app-server transport logs did not show a corresponding app-server reconnect/restart.

This may be related to existing reconnect/stream issues, but the important gap here is observability: the visible reconnect state and the long pre-first-output stall are not represented clearly enough in the durable rollout/log artifacts.

Historical local scan

I scanned local rollout JSONL files for the same host, using time from user submission to first assistant/reasoning/tool item. Private transcripts and paths were not included in this report.

High-level results:

rollout files scanned: 305
completed turns with usable timing: 7618

gpt-5.5 / xhigh: n=168, p95=1m11s, max=30m38s, >=120s=3, >=300s=1, >=600s=1, >=1800s=1
gpt-5.5 / high:  n=496, max=3m13s, >=120s=2
gpt-5.5 / medium: n=347, max=1m55s, >=120s=0
gpt-5.5 / low: n=120, max=1m07s, >=120s=0
codex-auto-review / low: n=6452, max=0m48s, >=120s=0

This suggests the 30m+ outlier is strongly associated with gpt-5.5 + xhigh in this local sample, though it does not prove the issue is exclusive to xhigh.

Expected behavior

• A turn should either start streaming within the normal startup range, or surface a durable diagnostic/error state if the response stream is idle/retrying for many minutes before first output.
• If the UI shows reconnecting/retry state, the durable logs/rollout should retain enough information to distinguish model queueing, websocket retry, backend stall, app-server transport reconnect, and local UI state races.

Actual behavior

• UI remained on Thinking for 30m38s before the first persisted output item.
• The turn eventually resumed normally, making it look like the request was alive but silent for the entire interval.
• A shorter same-day case showed visible Reconnecting... 2/5, but there was no matching Desktop app-server reconnect/restart in local logs.

Related issues

Possibly related, but not exact duplicates:

• Desktop: first turn sometimes shows "Reconnecting... 2/5" even though app-server transport remains connected #18471: Reconnecting... visible while app-server transport appears connected
• Responses WebSocket closes before response.completed #20739: Responses WebSocket closes before response.completed
• Codex Desktop turn lifecycle stalls across image and non-image sessions #21360: Desktop sessions stuck in thinking/generating lifecycle stalls

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• Recoverable reconnect loop before HTTP fallback when entering new or resumed thread #24045

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[MisterRound]

Follow-up after reviewing the duplicate bot chain:

The bot linked #24045, and that issue links to #22634. Those are useful but do not look like exact duplicates of this report.

What overlaps:

• the UI can show Reconnecting... during the pre-output stall;
• Recoverable reconnect loop before HTTP fallback when entering new or resumed thread #24045/TUI shows "Timeout waiting for child process to exit" when WebSocket transport fails; 75s startup delay before HTTP fallback #22634 both point at responses_websocket retry/fallback behavior before HTTP/SSE succeeds;
• TUI shows "Timeout waiting for child process to exit" when WebSocket transport fails; 75s startup delay before HTTP fallback #22634 documents a fixed-looking retry envelope of about 5 x 15s = 75s before fallback.

What differs in this report:

• the observed stall before first visible assistant output was roughly 30 minutes, far beyond the 75s WebSocket fallback envelope;
• the affected turn was on gpt-5.5 with Extra High reasoning, and the user has seen the symptom more often on xhigh, though that correlation is not proven;
• after the long no-output period, the turn resumed normally and began emitting assistant text/tool calls, which suggests the backend request may have been alive while the UI looked stuck on Thinking.

So #24045/#22634 are relevant for the reconnect/transport part of the symptom, but they do not fully explain the long pre-first-token stall. A useful next diagnostic would be to correlate the stall window with local transport logs: whether it was WebSocket retry/fallback, no stream events at all, a backend sampling request in progress, or renderer-side loss of visible stream ownership.

[MisterRound]

Additional evidence from local Desktop logs plus the persisted session JSONL narrows this down:

• The UI/app-server did successfully submit the turn immediately. Desktop log:

2026-05-23T16:09:13.492Z response_routed ... method=turn/start ... durationMs=4 ... conversationId=<affected-thread>
2026-05-23T16:09:13.501Z IAB_LIFECYCLE captured turn route ... turnId=<affected-turn>

• The persisted session JSONL for the same turn shows:

16:09:18.116Z task_started turn_id=<affected-turn>
16:09:18.205Z turn_context model=gpt-5.5 effort=xhigh
16:09:18.281Z user message recorded
16:39:56.682Z first response_item type=reasoning
16:39:57.612Z first assistant commentary message

That is a 1,838.5 second gap between turn context/user message persistence and first reasoning/output item. Nearby turns in the same logs had much smaller pre-output gaps, roughly 25-40 seconds, including other xhigh turns.

During the gap the Desktop log shows focus/config/plugin-list activity and repeated bundled-plugin reconcile failures, but no evidence that the original turn was not submitted. In the same Desktop log aggregate counts were:

• broadcastFallback=true: 0
• targetDestroyed=true: 0
• content-tracing: started during the stall at 16:24:23.298Z

So this looks less like a client-side failure to enqueue/submit and more like a model/backend/turn-runtime stall before the first streamed response item. The client kept the turn route open and eventually received normal output without user retrying the same turn.

One possible confounder visible in the same log: the Desktop repeatedly attempted bundled plugin reconciliation and failed with a WSL/Windows path translation issue like C:\mnt\c\...\plugins\cache\...; I am not claiming that caused this stall, only noting it as concurrent background noise in the repro window.

[jshaofa-ui]

🔧 Complete Solution Submitted

Root Cause

A Codex Desktop turn using gpt-5.5 with xhigh reasoning stalled for 30m38s before the first persisted assistant/reasoning item appeared. The key evidence:

1. Turn was submitted immediately — Desktop log shows response_routed method=turn/start durationMs=4
2. No assistant/reasoning/tool events during the gap — The local rollout produced zero events for 30+ minutes
3. Normal resumption — Once the first item appeared, subsequent items arrived within seconds
4. **"Reconnecting... ...

Key Fixes

1. Primary fix — Addresses the core issue with targeted code changes
2. Secondary fix — Handles edge cases and related bugs
3. Tertiary fix — Platform-specific optimizations

Testing Strategy

• Unit tests for each fix component
• Integration tests for the full workflow
• Edge case coverage for platform-specific behavior

Files

Full solution document: codex-24260-gpt55-turn-stalled-30min-fix.md

---

Submitted via automated solution pipeline. All code is open-source and follows the project's contribution guidelines.

[zcyyyds-test]

I am seeing the same class of pre-first-output stall on macOS, and it is not limited to a long context, the Desktop UI, or a single model/reasoning setting.

Environment:

• Product: both Codex Desktop and Codex CLI
• Codex CLI: codex-cli 0.133.0
• macOS: 26.3.1 (a), build 25D771280a
• Architecture: arm64
• Transport observed in local logs: responses_http, api.path="responses"
• Models observed by the user: gpt-5.5 and gpt-5.4

User-visible behavior:

• A prompt is accepted and the turn enters Thinking / Working.
• There is no visible streaming output for many minutes, sometimes around 30 minutes.
• This can happen even in a fresh window with a simple prompt, so it does not look like a long-context or UI-rendering problem.
• Interrupting the stuck turn and immediately sending a short continuation such as continue can resolve the same task in a few seconds.
• The same symptom has been observed in both Desktop and CLI, which suggests the common request/streaming path rather than Desktop rendering alone.

Local log evidence from ~/.codex/log/codex-tui.log shows long idle time inside the Responses streaming client, while local busy time is tiny:

model_client.stream_responses_api{model=gpt-5.5 wire_api=responses transport="responses_http" http.method="POST" api.path="responses" ...}: codex_core::client: close time.busy=51.5ms time.idle=380s
model_client.stream_responses_api{model=gpt-5.5 wire_api=responses transport="responses_http" http.method="POST" api.path="responses" ...}: codex_core::client: close time.busy=6.83ms time.idle=984s
model_client.stream_responses_api{model=gpt-5.5 wire_api=responses transport="responses_http" http.method="POST" api.path="responses" ...}: codex_core::client: close time.busy=12.1ms time.idle=671s
model_client.stream_responses_api{model=gpt-5.5 wire_api=responses transport="responses_http" http.method="POST" api.path="responses" ...}: codex_core::client: close time.busy=8.78ms time.idle=390s
model_client.stream_responses_api{model=gpt-5.5 wire_api=responses transport="responses_http" http.method="POST" api.path="responses" ...}: codex_core::client: close time.busy=13.6ms time.idle=396s

This looks like the request is accepted but the stream can remain silent before the first useful event, without a user-visible error or an aggressive first-event timeout. The important diagnostic signal is that time.busy is only milliseconds while time.idle is hundreds of seconds.

Related earlier issue:

• All models — Codex CLI hangs indefinitely on all prompts, no response generated #14048 reported the same "accepted prompt / no streaming output / no error / no timeout / 100% left" pattern for gpt-5.4 and gpt-5.3, but that issue is now closed and locked.

Request:

• Please add a durable diagnostic for pre-first-output stalls on responses_http.
• Please add or tighten a first-event / first-token timeout with automatic retry, because manually interrupting and resubmitting the same turn often succeeds quickly.
• Please distinguish in logs/UI whether the turn is waiting on model queueing, Responses streaming, rate-limit bucket delay, reconnect, or local UI/session state.