fix: reorder tool_result blocks to match tool_use order (#11804)

[roomote]

This PR attempts to address Issue #11804 -- Claude requests failing with HTTP 400 when multiple tool calls run concurrently due to tool_result order mismatch.

Changes

Root cause: When the Anthropic API returns multiple tool_use blocks in a single assistant turn, tool_result blocks could be pushed into userMessageContent in completion order rather than the original tool_use order. The Anthropic Messages API requires them to match, so out-of-order results trigger HTTP 400.

Fix: Added a reorderToolResults() helper at the end of validateAndFixToolResultIds() in src/core/task/validateToolResultIds.ts. After all existing validation (deduplication, ID correction, missing result injection), tool_result blocks are sorted to match the tool_use order from the preceding assistant message, matched by tool_use_id.

Key design decisions per the approved plan and reviewer feedback:

• Non-tool-result blocks (text, image) stay in their original positions
• Only tool_result blocks are reordered relative to each other (stable)
• Reordering runs on both the early-return path (valid IDs) and the fix-up path
• Returns null (no-op) when already in correct order

Tests

Added 4 new test cases covering:

• Out-of-order tool_results (reversed order)
• Non-tool-result blocks preserving position during reorder
• Already-ordered tool_results (no-op)
• Reordering combined with missing result injection

Updated 2 existing tests whose expected order changed due to the new reordering behavior.

Feedback and guidance are welcome.

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