# Skill Update Dates Research - Document Index
**Research Date:** December 31, 2025
**Status:** Complete and Ready for Implementation
**Total Size:** 36 KB across 4 documents
## Document Guide
### 1. Main Research Document (18 KB)
**File:** `skill-update-dates-implementation-2025-12-31.md`
**Contains:**
- Executive summary of approach
- Current architecture analysis with file locations
- Data source comparison (mtime vs git commit date)
- Detailed implementation approach with 3 phases
- Architecture diagrams
- Performance implications
- Risk assessment matrix
- Complete file modification checklist
- Related code patterns in codebase
**Best for:** Complete understanding of the system and long-term implementation strategy
**Key sections:**
- Current Architecture (explains 4 main components)
- Data Sources (pros/cons of each approach)
- Implementation Approach (detailed steps)
- Files to Modify (all 3 files listed)
- Performance Analysis
- Risk Assessment
---
### 2. Quick Reference Guide (5 KB)
**File:** `skill-update-dates-quick-reference-2025-12-31.md`
**Contains:**
- Key code locations with file paths and line numbers
- Import statements to add
- Backward compatibility notes
- Testing locations
- ChromaDB query examples
- Files to modify summary table
- Phase 1 checklist
- Expected impact assessment
**Best for:** Quick lookup during implementation
**Key information:**
- Where to add the datetime field (which file, which class)
- Where to capture the date (which function, which line)
- Where to store the date (ChromaDB metadata format)
- What tests need updating
---
### 3. Detailed Code Changes (13 KB)
**File:** `skill-update-dates-code-changes-2025-12-31.md`
**Contains:**
- Exact code changes for all 3 files
- Line-by-line before/after examples
- 9 specific code changes for skill.py
- 3 specific code changes for skill_manager.py
- 1 specific code change for vector_store.py
- Import statement requirements
- Testing requirements summary
**Best for:** Implementation - copy/paste ready code changes
**How to use:**
1. Open each file mentioned
2. Find the section for that file
3. Follow the "Current" to "Change to" examples
4. Make the modifications
5. Run tests
---
## Quick Start Path
1. **First read:** Quick Reference (5 minutes)
- Understand scope and locations
2. **Review:** Main Research (15 minutes)
- Understand why this approach
- Review architecture
- Check risk assessment
3. **Implement:** Code Changes (1-2 hours)
- Follow the detailed examples
- Run provided tests
- Verify with actual SKILL.md files
---
## Key Findings Summary
### Best Approach: File Modification Time (mtime)
- **Why:** Simple, no dependencies, works everywhere
- **How:** `file_path.stat().st_mtime`
- **Where:** SkillManager._parse_skill_file()
- **Format:** Python datetime with UTC timezone
### Architecture Overview
```
SKILL.md file (contains skill definition)
↓
SkillManager._parse_skill_file()
↓ (capture mtime here)
Skill dataclass
↓
IndexingEngine.index_skill()
↓ (routes to two stores)
├─ VectorStore (store in ChromaDB metadata)
└─ GraphStore (optional for Phase 2)
```
### Implementation Scope
- **Files to modify:** 3
- **Lines to add:** ~20
- **Lines to modify:** ~15
- **Breaking changes:** None
- **New dependencies:** None (datetime is stdlib)
- **Backward compatible:** Yes
### Phase 1 (Recommended First)
- Add field to Skill model
- Capture mtime in SkillManager
- Store in ChromaDB metadata
- Update serialization
- Time: 2-3 hours
- Risk: Minimal
### Phase 2 (Optional)
- Date-based filtering
- Sort by recency
- CLI flags
- Time: 2-3 hours
- Risk: Low
### Phase 3 (Future Enhancement)
- Git commit date extraction
- Update notifications
- Skill freshness scoring
- Time: 4+ hours
- Risk: Medium
---
## Files Analyzed (Codebase Research)
### Core Files:
1. `src/mcp_skills/models/skill.py` - Skill data models
2. `src/mcp_skills/services/skill_manager.py` - Skill lifecycle
3. `src/mcp_skills/services/indexing/engine.py` - Indexing orchestration
4. `src/mcp_skills/services/indexing/vector_store.py` - ChromaDB integration
### Supporting Files:
5. `src/mcp_skills/models/repository.py` - Date pattern reference
6. `src/mcp_skills/services/repository_manager.py` - Git integration reference
7. `tests/test_indexing_engine.py` - Existing test structure
---
## Current ChromaDB Metadata
**Currently stored:**
- `skill_id` - Unique identifier
- `name` - Skill name
- `category` - For filtering
- `tags` - Comma-separated
- `repo_id` - Repository identifier
**Will add:**
- `updated_at` - ISO format datetime string
---
## Existing Patterns in Codebase
The Repository model already implements datetime tracking:
- **File:** `src/mcp_skills/models/repository.py`
- **Field:** `last_updated: datetime`
- **Pattern:** Uses `datetime.now(UTC)` from `datetime` module
- **Serialization:** `.isoformat()` to string
- **Deserialization:** `datetime.fromisoformat()` from string
**Recommendation:** Follow the exact same pattern for Skill model.
---
## Import Statements Needed
**In skill.py:**
```python
from datetime import datetime
```
**In skill_manager.py:**
```python
from datetime import UTC, datetime # Add UTC to existing imports
```
---
## Testing Locations
**Existing test fixtures:**
- `/Users/masa/Projects/mcp-skillset/tests/test_indexing_engine.py` (line 25-71)
**New tests needed:**
1. Datetime serialization/deserialization
2. Mtime capture in _parse_skill_file()
3. ChromaDB metadata verification
---
## Phase 1 Checklist
- [ ] Add datetime import to skill.py
- [ ] Add updated_at field to Skill dataclass
- [ ] Add updated_at field to SkillMetadata dataclass
- [ ] Update Pydantic models (SkillModel, SkillMetadataModel)
- [ ] Update to_dict() methods for serialization
- [ ] Update from_dict() methods for deserialization
- [ ] Add UTC import to skill_manager.py
- [ ] Capture mtime in _parse_skill_file()
- [ ] Add updated_at to skill_data dict
- [ ] Pass updated_at to Skill constructor
- [ ] Update metadata dict in vector_store.py
- [ ] Update test fixtures
- [ ] Write serialization tests
- [ ] Write mtime capture tests
- [ ] Run full test suite
- [ ] Test with actual skill files
---
## Related Linear Tickets
**Create ticket with reference to this research:**
- Title: "Add update timestamps to skills"
- Description: Include link to this research documentation
- Checklist: Use the Phase 1 checklist above
- Estimate: 2-3 hours for Phase 1
---
## Future Enhancements
**Phase 2: Query Support**
- Add date filter parameters to search
- Implement date range filtering
- Add sorting by date
- Add CLI flags (--updated-after, --updated-before)
**Phase 3: Advanced Features**
- Git commit date extraction (more accurate)
- Skill update notifications
- "Recently updated" recommendations
- Migration script for existing indices
---
## Performance Impact
- **Speed:** Negligible (<1% overhead)
- **Memory:** ~56 bytes per skill (datetime object)
- **Storage:** ~30 bytes per skill (ISO string in ChromaDB)
- **Indexing:** No impact on embedding generation
- **Search:** Optional filters add minimal overhead
---
## Backward Compatibility
- **Field is optional:** `updated_at: datetime | None = None`
- **Existing skills:** Will have None value (graceful handling)
- **No API breaks:** Fully backward compatible
- **Migration:** Can add dates to existing skills later if needed
---
## Risk Assessment
**Low Risk:**
- Optional field (no breaking changes)
- File mtime always available
- Follows existing patterns
- No external dependencies
**Medium Risk:**
- Serialization edge cases (handle None)
- Timezone consistency (use UTC)
- ChromaDB query syntax
**Mitigation:**
- Comprehensive unit tests
- Clear None handling
- Documentation
- Gradual rollout
---
## Success Criteria
Phase 1 is complete when:
1. All 3 files modified with correct datetime handling
2. Updated_at field populated for new skills
3. ChromaDB metadata includes updated_at
4. Serialization/deserialization round-trips work
5. All existing tests pass with updated fixtures
6. New tests for datetime handling pass
7. Manual testing with actual SKILL.md files succeeds
---
## Contact & Questions
If questions arise during implementation:
1. Check the main research document for context
2. Review the code changes document for exact syntax
3. Check the quick reference for locations
4. Verify against existing Repository model pattern
---
**Next Step:** Start with Phase 1 implementation using the code changes document.