Claude misinterprets 'Continue from where you left off' system message, truncating response after tool use

Description

In a long conversation involving multiple tool calls (WebSearch, Bash, Read), Claude completed a WebSearch call and then received a system recovery message Continue from where you left off.. Claude misinterpreted this as a "no response needed" signal, replied only with No response requested., and ended its turn — leaving the already-fetched search results unsynthesized for the user. The user had to explicitly follow up ("you only replied with part of it and then stopped") to get the actual answer.

Expected Behavior

Continue from where you left off. should be recognized as an instruction to continue the previous unfinished output, prompting Claude to synthesize and emit the response it had been about to write — not be treated as a system message that requires no response.

Reproduction

• Model: Claude Opus 4.6 (1M context) — claude-opus-4-6[1m]
• Environment: Claude Code CLI on macOS 26.4 (Apple M4)
• Scenario: Long conversation containing multiple WebSearch + Bash + Read tool calls
• Trigger: Immediately after a WebSearch tool call completes, the harness sends Continue from where you left off.

Impact

The search result was actually retrieved successfully, but never made it to the user. The user perceives this as Claude "stopping mid-reply" and has to manually prompt for the rest. This is especially frustrating in long research sessions where the user has already waited for the tool call to finish.

Notes

Originally observed in a Chinese-language conversation; the user's exact follow-up was "你就回复一部分就不回复了" ("you only replied with part of it and then stopped").