Sessions may stop responding (JSONL stops being written) — Claude Code

Quick fix

Update CC Switch to the latest 4.0 release and retry. If it still hangs, temporarily bypass CC Switch and submit complete reproduction details.

Symptom

Error outputCopy

会话有概率停止响应（JSONL 不再写入，不再发新 API 请求，UI 冻结）。

English translation

Sessions may stop responding (JSONL stops being written, no new API requests are sent, and the UI freezes).

Cause

In routing mode on CC Switch v3.16.2, a DeepSeek-compatible Anthropic provider undergoes thinking-history normalization. When an assistant history message contains `tool_use` but has no `thinking` or only empty `thinking`, the system may pre-inject a synthetic `"tool call"` thinking block. The reporter observed that after `cache_read` exceeded about 150k tokens in a long session, the main response frequently entered `thinking` blocks, visible `text` blocks became nearly empty, and the session could then stop responding.

After bypassing CC Switch, the reporter did not observe the issue again with 300k+ `cache_read`. This makes CC Switch request transformation a likely trigger, but the issue did not establish that all DeepSeek-compatible Anthropic endpoints had removed the thinking backpass constraint. A reactive injection approach was submitted in PR #4210, but the issue was closed after timing out without new reproduction details. It was not confirmed that the PR was merged or that the issue was fixed. A maintainer said that 4.0 substantially refactored the related functionality and recommended updating and retesting.

Fix

1. 1

   Update CC Switch to the latest 4.0 release, then retest with the same DeepSeek-compatible Anthropic provider and long-session procedure.

2. 2

   Check whether the main response still enters `thinking` blocks and whether JSONL writes, API requests, and the UI stop again after about 3 minutes of inactivity or continued long-context conversation.

3. 3

   If the issue still occurs after updating, temporarily bypass CC Switch. After bypassing CC Switch while keeping the rest of the upstream path unchanged, the reporter no longer observed 400, thinking/text collapse, or session freezes.

4. 4

   If the issue persists, submit the CC Switch version, operating system, complete reproduction steps, and relevant logs or screenshots again.

Affected Versions

ToolClaude Code

Version受影响版本：3.16.2

PlatformsWindows

Source Issues

This page is distilled from 1 real issues

• #4208Synthetic "tool call" thinking placeholders may break long DeepSeek-compatible Anthropic sessions

FAQ

(No FAQ yet)

Related problems

CC Switch is currently a black box; users cannot customize processing logicThis is a feature request for programmable routing transformation scripts in CC Switch; the original post has no verifiable official solution.1 issues mergedFormat conversion error: No choices in response - CC SwitchClinePass wraps the response in a data envelope, breaking parsing. Upgrade CC Switch to a version with the fix, or use a local proxy to unwrap response.data.1 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