feat(core): add change frequency to codebase map (#94)

[prosdev]

Summary

Adds change frequency data to the codebase map, showing how often directories are modified. This helps identify "hot" areas of the codebase.

Changes

Types (packages/core/src/map/types.ts)

• Added ChangeFrequency interface with:
  • last30Days: Commits in the last 30 days
  • last90Days: Commits in the last 90 days
  • lastCommit: Date of most recent commit
• Added includeChangeFrequency option to MapOptions
• Added changeFrequency field to MapNode

Core (packages/core/src/map/index.ts)

• Added MapGenerationContext interface for flexible input
• Implemented computeChangeFrequency() function:
  • Collects all directory paths from tree
  • Queries git for commits in each directory (last 90 days)
  • Counts commits in 30-day and 90-day windows
  • Applies data to tree nodes
• Updated formatCodebaseMap() to display frequency indicators:
  • 🔥 5+ commits this month (hot)
  • ✏️ 1-4 commits this month (active)
  • 📝 commits in last 90 days

Adapter (packages/mcp-server/src/adapters/built-in/map-adapter.ts)

• Added repositoryPath config option
• Added includeChangeFrequency parameter to tool schema
• Creates LocalGitExtractor when change frequency is requested
• Passes context to generateCodebaseMap()

Tests

• Added 3 tests for change frequency feature:
  • Include frequency when enabled
  • Skip frequency when disabled
  • Format frequency in output

Example Output

├── packages/ (500 components) 🔥 12 commits this month
│   ├── core/ (200 components) ✏️ 3 commits this month
│   ├── mcp-server/ (150 components) 🔥 8 commits this month
│   └── cli/ (50 components) 📝 5 commits (90d)

Closes

Closes #94

Part of

Epic: Intelligent Git History (v0.4.0) #90