Code Review

✅ APPROVED - Important bug fix with comprehensive solution

This PR fixes a significant issue where plugin metadata and titles were being lost during tool execution. The implementation is well-thought-out and includes proper test coverage.

What this PR does well:

• Comprehensive fix: Addresses metadata loss from both context.metadata() calls and structured plugin returns
• Backward compatibility: Maintains support for legacy string-only plugin returns
• Robust error handling: Validates return types and provides clear error messages
• Excellent test coverage: Three comprehensive test cases cover all scenarios
• Type safety: Uses proper type guards for runtime validation

Code Quality Assessment:

No Critical Issues Found ✅
No Security Issues Found ✅
No Performance Issues Found ✅

Technical Analysis:

Strengths:

1. State tracking: Captures metadata state via closure variables (title, meta)
2. Flexible input handling: Supports both structured objects and plain strings
3. Proper merging: Truncation metadata correctly overlays plugin metadata
4. Type validation: Runtime checks ensure safe property access

Architecture:

• Good: Clean separation between plugin context enhancement and result processing
• Good: Maintains existing truncation behavior while preserving metadata
• Good: Error handling guides developers toward correct return format

Code Deep Dive:

// Smart return type detection
const item = plain(result) ? result : undefined
const text = item && typeof item.output === "string" ? item.output : 
             typeof result === "string" ? result : undefined

This logic properly handles both legacy (string) and new (structured) return formats.

Minor Suggestions:

1. Consider extracting the type guard plain() to a shared utility if used elsewhere
2. The error message could include the actual return type for better debugging

Test Coverage Analysis:

Excellent test coverage with three scenarios:

• ✅ Metadata set via context.metadata()
• ✅ String plugin results (legacy)
• ✅ Structured plugin results (new format)

All tests properly verify title, output, metadata, and truncation behavior.

Overall Assessment: This is a high-quality fix that resolves a real issue affecting plugin developers. The implementation is robust and well-tested.