Reasoning tokens not expanding in Codex UI - "Worked for X" shows time but no trace #45

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1. lidge-jun commented on Jun 29, 2026

   

   lidge-jun

   on Jun 29, 2026

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   Investigated end-to-end, including the codex-rs consumer side.

   Root cause (confirmed): Codex renders the expandable reasoning trace from the Responses reasoning item's summary[] channel. opencodex maps chat-completions reasoning_content to a raw-reasoning item with summary: [] and only content: [{reasoning_text}], so the Codex app shows the "Worked for Xs" timer (driven separately by elapsed time / reasoning_tokens) but has nothing to expand.

   I traced this through codex-rs main to be sure it isn't a client bug:

   • codex-api/src/sse/responses.rs parses both response.reasoning_summary_text.delta (→ summary) and response.reasoning_text.delta (→ content).
   • core/src/session/turn.rs + core/src/event_mapping.rs carry content into raw_content (not dropped), but the persisted/expandable block comes from the summary channel (tui/src/history_cell/messages.rs ReasoningSummaryCell).
   • Native OpenAI models populate summary; routed chat models don't, which is exactly the report.

   Fix (planned, opencodex-side only): route chat reasoning_content through the summary channel so the final reasoning item has a non-empty summary[] (treat it like the existing thinking_delta path). Non-OpenAI chat providers don't send a separate condensed summary, so their full reasoning_content is the human-visible thinking and belongs in summary. No codex-rs change needed.

   Two sub-cases (look identical to the user):

   • (A) Provider returns reasoning_content (DeepSeek-R-style) → opencodex formatting gap, fixed by the above.
   • (B) Provider returns no reasoning at all (many free models) → nothing to expand; "Worked for Xs" is pure elapsed time. Model limitation, not an opencodex bug.

   To confirm which applies to a specific model, a raw upstream chunk showing whether choices[].delta.reasoning_content is ever present would help. Fix for (A) is planned.
2. lidge-jun commented on Jun 29, 2026

   

   lidge-jun

   on Jun 29, 2026

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   @Rezhnn I couldnt see reasoning summary on app or cli I succeed to parse on exec mode could you hand me a some screenshot and config set?
3. lidge-jun

   added a commit that references this issue on Jun 29, 2026

   fix(bridge): route chat reasoning_content to expandable summary channel

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   3183154
4. Rezhnn

   closed this as completedon Jul 12, 2026
5. AlinJiang

   added a commit that references this issue on Aug 18, 2026

   fix(responses): route raw reasoning through the expandable summary ch…

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   e7d1489
6. AlinJiang commented on Aug 18, 2026

   

   AlinJiang

   on Aug 18, 2026

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   Filing a follow-up note since this was closed with a fix that never shipped:

   1. The fix commit 3183154509 ("route chat reasoning_content to expandable summary channel") landed June 29 but its changes are not present in any released version - not 2.24.2, not 2.25.0, not current main. The bridge was rewritten in July-August and the content-channel shaping came back.
   2. Since then the situation changed further: DeepSeek now routes Responses inbound through its native /responses endpoint with no translation (registry modelWireDefaults), so the bridge fix alone would not cover DeepSeek anyway - the raw reasoning_text.delta events now come straight from DeepSeek's own Responses API.

   I verified all of this live against DeepSeek V4 Flash through the current proxy, then sent a PR that covers both wires:

   • fix(responses): route raw reasoning through the expandable summary channel (bridge + passthrough) #2007: routes raw reasoning through the expandable summary channel in the streaming/buffered bridge and adds a payload rewrite for the native-Responses passthrough (converts reasoning_text.delta/.done and reasoning item content into the summary channel, gated on statelessResponses / preserveReasoningContentModels).
   • Replay is preserved: DeepSeek's Responses API accepts summary-shaped reasoning input items (verified live, including a tool-call continuation - no 400), and the bridge replay cache handoff is untouched.

   Until that (or an equivalent) merges, the workarounds are: show_raw_agent_reasoning = true in ~/.codex/config.toml makes the CLI TUI render the raw channel, but Codex Desktop's expandable trace (which only reads summary[]) stays empty.
7. AlinJiang

   added 2 commits that reference this issue on Aug 18, 2026

   fix(responses): route raw reasoning through the expandable summary ch…

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   10fbc36

   fix(responses): route raw reasoning through the expandable summary ch…

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   56752d7
8. ropepop commented on Aug 18, 2026

   

   ropepop

   on Aug 18, 2026

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   Adding a second surface for the same stored item, still present on @bitkyc08/opencodex@2.24.2 with xai/grok-4.6 (openai-chat).

   This issue’s Desktop report is: the chip has nothing to expand. On Codex Remote (iOS) the same empty summary[] + content: [{ type: "reasoning_text" }] item is visible. Private thinking streams first (response.reasoning_text.delta), then the normal progress line replaces it, and an italic tail fragment stays on screen.

   One live thread: 179 / 179 reasoning items were that empty-summary shape. Official summary text: 0 characters. The leftover italic on the phone was the tail of a stored reasoning_text blob, not the following progress message. Codex Desktop on the same turn did not show that private text.

   Separate Remote leak/flicker report: #2064
9. agentHits

   added 2 commits that reference this issue on Sep 17, 2026

   fix(bridge): route chat reasoning_content to expandable summary channel

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   446e91c

   fix(responses): route raw reasoning through the expandable summary ch…

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   2ab65c6