fix: prevent orphaned tool results during interrupted tool execution

[michaeljabbour]

Summary

Fixes a critical bug in context compaction that caused orphaned tool results and API errors when users interrupted tool execution.

Bug Description

The _check_tool_pair_removable() method was incorrectly marking tool pairs as removable even when not all tool_results had been received yet. This caused the assistant message with tool_calls to be removed prematurely, leaving orphaned tool_result messages that triggered Anthropic API errors.

Root Cause

• Method only checked if tool_results existed in the block range
• Did not verify that EVERY tool_call had a corresponding tool_result
• Returned all_removable=True after finding just one result

Trigger Scenario

1. Assistant makes tool_calls [A, B, C]
2. Result A arrives
3. User interrupts with 'continue' message
4. Compaction runs, finds only result A
5. BUG: Returns all_removable=True anyway
6. Removes assistant message containing all tool_calls
7. Results B and C arrive later as orphans
8. API error: tool_use ids were found without tool_result blocks

The Fix

• Added 'found' flag to track each individual tool_call
• Only set all_removable=True if ALL tool_calls have results
• Added detailed docstring explaining the critical validation
• Added 2 regression tests to prevent reintroduction of this bug

Files Changed

• amplifier_module_context_simple/__init__.py: Fixed _check_tool_pair_removable() method (18 lines)
• tests/test_tool_pair_compaction.py: Added 2 regression tests (108 lines)

Impact

• User-facing: Fixes session crashes when users interrupt tool execution
• Safety: Prevents data loss from dropped tool results
• Backward compatible: No API changes, just more robust logic

Testing

Added two comprehensive regression tests:

1. test_incomplete_tool_results_not_removed() - Verifies bug is fixed
2. test_complete_tool_results_can_be_removed() - Verifies normal case still works

Type

fix