Problem

Users are encountering the following error when the API is called:

ApiError: undefined: Expected toolResult blocks at messages.8.content for the following Ids: toolu_01HqaicajCMgEJ78exc2Wwmg, toolu_01RaoEkKUYn1rErRxepLQGZD

This error occurs when an assistant message contains tool_use blocks but the subsequent user message is missing the corresponding tool_result blocks entirely. This can happen during parallel tool execution scenarios (e.g., when the model tries to execute the new_task tool in parallel with other tools).

Root Cause

The existing validateAndFixToolResultIds() function only fixed ID mismatches between tool_result and tool_use blocks, but didn't handle the case where tool_result blocks are completely missing.

Solution

Enhanced validateAndFixToolResultIds() to:

1. Detect missing tool_result blocks - Check if any tool_use IDs don't have corresponding tool_result blocks
2. Report to telemetry - Added MissingToolResultError class for structured error tracking
3. Auto-fix by adding placeholder blocks - Add missing tool_result blocks with content: "Tool execution was interrupted before completion."

Changes

src/core/task/validateToolResultIds.ts

• Added new MissingToolResultError class for telemetry tracking
• Enhanced validation logic to detect and add missing tool_result blocks
• Added telemetry reporting for missing tool_results

src/core/task/__tests__/validateToolResultIds.spec.ts

• Added comprehensive tests for:
  • Adding missing tool_result for single/multiple tool_use blocks
  • Partial missing (some exist, some don't)
  • Empty user content arrays
  • MissingToolResultError class
  • Telemetry for missing tool_result detection

Testing

• All 23 unit tests pass
• Full test suite passes (4625 tests)