[Yeachan-Heo]

Summary

Parallel tool calls in a single assistant message now have their results merged into one following user message, as required by the Anthropic Messages API.

Problem

When an assistant message contains multiple tool_use blocks (parallel tool calls), the convert_messages() function was emitting one user message per tool_result. The API requires all tool_results to arrive in the single message immediately following the assistant message, so the provider rejected requests with HTTP 400.

Example message sequence (before):

• messages[1]: assistant [tool_use, tool_use]
• messages[2]: user [tool_result] <- correct
• messages[3]: user [tool_result] <- ERROR: one message too late

Solution

The convert_messages() function now uses fold() with absorb_tool_result_message() to merge consecutive tool-result-only messages. Both implementations (rusty-claude-cli and tools crate) are updated.

Example message sequence (after):

• messages[1]: assistant [tool_use, tool_use]
• messages[2]: user [tool_result, tool_result] <- both in same message ✓

Testing

A new regression test (parallel_tool_result_pairing.rs) exercises the parallel tool call scenario against the mock Anthropic service and verifies the pairing contract.

[Yeachan-Heo]

Closing as superseded: the parallel tool-result pairing fix for #3361 already landed on main in b8f93af (from #3360), with the regression test rust/crates/rusty-claude-cli/tests/parallel_tool_result_pairing.rs, and #3361 is closed by that commit. This branch would duplicate it.

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[repo owner's gaebal-gajae (clawdbot) 🦞]

[XinwangTao]

这个修复很有必要：并行 tool_use 场景下 tool_result 必须全部放在紧随 assistant 消息之后的那条 user message 里，之前逐条拆分会被 Anthropic API 以 HTTP 400 拒绝。用 fold + absorb_tool_result_message 合并两个实现并补了回归测试，覆盖到位。

[XinwangTao]

这个修复很有必要：并行 tool_use 场景下 tool_result 必须全部放在紧随 assistant 消息之后的那条 user message 里，之前逐条拆分会被 Anthropic API 以 HTTP 400 拒绝。用 fold + absorb_tool_result_message 合并两个实现并补了回归测试，覆盖到位。