Summary

When a request is aborted mid-tool-call, OpenClaw's session repair mechanism creates a synthetic tool result, but the API subsequently rejects the session with:

messages.X.content.Y: unexpected tool_use_id found in tool_result blocks: toolu_XXXX. Each tool_result block must have a corresponding tool_use block in the previous message.

Steps to Reproduce

1. Start a conversation that involves tool calls
2. Interrupt/abort a request while a tool call is in progress (network hiccup, timeout, or user interruption)
3. The assistant message gets stopReason: "aborted" with a partial/incomplete tool call (has partialJson)
4. OpenClaw detects the orphan and inserts a synthetic error result:

   {"role":"toolResult","toolCallId":"toolu_XXXX","content":[{"type":"text","text":"[openclaw] missing tool result in session history; inserted synthetic error result for transcript repair."}],"isError":true}

5. On next user message, the API rejects with tool_use_id mismatch

Root Cause

When reconstructing messages to send to the API, the aborted assistant message's tool_use block is either:

• Not included (because it's incomplete/partial), OR
• Malformed in a way the API doesn't recognize

But the synthetic tool_result IS included, creating a mismatch.

Session Log Evidence

Line N:   assistant → stopReason: "aborted", toolCall id: toolu_01Hoo9VQsRSw7Nafu2QFt8KK (partialJson present)
Line N+1: toolResult → toolCallId: toolu_01Hoo9VQsRSw7Nafu2QFt8KK (synthetic repair)
Line N+2: user message
Line N+3: assistant → stopReason: "error", API rejects with tool_use_id mismatch

Suggested Fix

When an aborted message contains a partial/incomplete tool call:

1. Option A: Strip BOTH the aborted tool_use AND its synthetic result before sending to API
2. Option B: Complete/normalize the tool_use structure so it's valid before adding a result
3. Option C: Don't insert synthetic results for aborted tool calls at all

Workaround

Manually delete/reset the corrupted session file:

rm ~/.openclaw/agents/main/sessions/<session-id>.jsonl

Environment

• OpenClaw: 2026.2.2-3
• Model: claude-opus-4-5 (Anthropic)
• OS: Ubuntu (WSL2)