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thinking too short Codex

Quick fix

Start a new Codex conversation to temporarily avoid it. The original post suggests filtering empty or overly short thinking; an official fix is unverified.

Symptom

Section titled “Symptom”
Error output
{"error":{"message":"CC Switch local proxy failed while handling Codex endpoint /responses. Provider: 基元律动; model: deepseek-v4-flash-0731; upstream_status: HTTP 400; cause: messages.41.content.0.thinking 长度不足","type":"invalid_request_error","code":"cc_switch_upstream_error","param":null,"provider":"基元律动","model":"deepseek-v4-flash-0731","endpoint":"/responses","upstream_status":400}}
English translation

{"error":{"message":"CC Switch local proxy failed while handling Codex endpoint /responses. Provider: 基元律动; model: deepseek-v4-flash-0731; upstream_status: HTTP 400; cause: messages.41.content.0.thinking insufficient length","type":"invalid_request_error","code":"cc_switch_upstream_error","param":null,"provider":"基元律动","model":"deepseek-v4-flash-0731","endpoint":"/responses","upstream_status":400}}

Cause

Section titled “Cause”

This open report states that DeepSeek-series models may output empty or overly short `thinking` blocks when streaming through an Anthropic-compatible interface. After the CC Switch local proxy writes them to Codex conversation history, the next request sends them upstream again; the upstream returns HTTP 400 because the `thinking` length is insufficient. The reporter found retries in the same conversation ineffective, while starting a new conversation avoided the issue.

A comment on the same issue also reports HTTP 400 for `tool_call_id 长度不足`: when field rewriting from Responses to Chat is incomplete, using a sub-agent or agent feature can trigger this variant. That comment involves different versions, models, and upstream formats, with no verified unified fix. The original post remains open and should not be considered fixed.

Fix

Section titled “Fix”

  1. After `thinking 长度不足`, start a new Codex conversation to avoid the empty thinking record already written to conversation history.

  2. The original post provides a temporary option: use https://github.com/moyi-math/cc-switch-thinking-filter to discard empty thinking in responses and strip residual history in requests; follow that project's instructions.

  3. A fix in the CC Switch proxy itself remains unconfirmed. Follow the source issue for handling of empty or overly short thinking blocks.

Affected Versions

Section titled “Affected Versions”
ToolCodex
VersionUnknown
PlatformsWindows

Source Issues

Section titled “Source Issues”

This page is distilled from 1 real issues

FAQ

Section titled “FAQ”

(No FAQ yet)

Section titled “Related problems”
api failed deserialize json body intoDepending on the error: roll Claude Code back, upgrade cc-switch, turn the local proxy off, or stop sending unsupported fields.8 issues mergedThe `content[].thinking` in thinking modeSome variants remain unresolved: upgrade to a version with the thinking history normalization fix; for Codex routed through DeepSeek, use a version with the…13 issues mergedAPI Error: 400 Param Incorrect Claude CodeUpgrade CC Switch to v3.16.2+ to fix 400 errors caused by missing reasoning_content in MiMo thinking mode.4 issues merged

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