Analyzing Git Sessions

Core Responsibility

Generate structured analysis of git activity for specified timeframe or commit range, including commit history, file changes, statistics, and optional diffs.

Inputs

Accept from user:

• Time range: "last 2 hours", "since 10am", "today", "since 2025-10-23 14:00"
• Commit range: "abc123..def456", "HEAD~5..HEAD", "feature-branch..main"
• Optional filters: Specific paths, authors, or file types
• Output depth: Concise (default), Detailed, or Code Review format

Working Process

Step 1: Parse and Validate Input

1. Determine range type:

   • Time-based: Parse relative or absolute time
   • Commit-based: Validate commit references exist
   • Branch-based: Resolve branch names to commits

2. Validate git repository:

   git rev-parse --git-dir
   

3. Check range has commits:

   git log <range> --oneline | head -1
   

   If empty, inform user and exit.

Step 2: Extract Commit History

# Get all commits in range
git log <range> --oneline --no-decorate

# Get detailed commit info
git log <range> --format="%h|%an|%ar|%s" --no-decorate

# Count commits
git log <range> --oneline | wc -l

Store commit data for summary.

Step 3: Generate Statistics

Overall change statistics:

# Summary stats (insertions/deletions by file)
git diff <start>..<end> --stat

# Numeric stats for parsing
git diff <start>..<end> --numstat

# Count total changes
git diff <start>..<end> --shortstat

Author breakdown (if multiple authors):

git shortlog <start>..<end> -sn

File categorization:

• Identify new files (show in status "A")
• Identify deleted files (show in status "D")
• Identify renamed files (show in status "R")
• Modified files with change magnitude

Step 4: Identify Key Files for Detailed Analysis

Prioritization rules:

1. Large changes (>100 lines modified): Always include
2. New files: Include (especially if >50 lines)
3. Deleted files: Note but don't diff
4. Architecture files: build.gradle.kts, AndroidManifest.xml, module configs
5. Test files: Flag separately for test coverage assessment

Extract key file list:

# Files changed with line counts
git diff <start>..<end> --numstat | sort -rn -k1 -k2

Limit to top 10 files by default to avoid context overflow.

Step 5: Generate Selective Diffs (Based on Depth)

Concise mode: No diffs, stats only

Detailed mode: Diffs for top 3-5 key files

git diff <start>..<end> -- path/to/key/file.kt

Code Review mode: Diffs for all modified files, grouped by module

# Group by directory
git diff <start>..<end> --name-only | cut -d'/' -f1-2 | sort -u

# Generate diffs per module
for module in modules; do
  git diff <start>..<end> -- $module/
done

Context overflow protection:

• If >10 files changed significantly, limit to top 5 diffs
• Warn user: "Showing top 5 files by change size. Request specific files for full diffs."

Step 6: Present Structured Summary

Format based on depth:

Concise Summary

## Git Session Summary

**Range**: <start-commit> to <end-commit> (<timeframe>)
**Commits**: X commits by Y author(s)
**Files Changed**: A modified, B added, C deleted
**Net Changes**: +X -Y lines

### Commits

- abc123 Commit message 1
- def456 Commit message 2
  ...

### Top Files Changed

1. path/to/file1.kt (+50 -20)
2. path/to/file2.kt (+30 -15)
   ...

Detailed Summary

Includes:

• Full commit list with authors and timestamps
• Complete file list with change stats
• Author breakdown
• Top 3-5 diffs for review

Code Review Format

## Code Review Summary

### Overview

- **PR Title**: [Suggested from commit messages]
- **Changes**: X files across Y modules
- **Scope**: [Inferred from changed files]

### Commits

[Formatted commit list suitable for PR description]

### Changes by Module

**Module: app**

- file1.kt: Description of changes
- file2.kt: Description of changes

**Module: core**
...

### Key Changes

[Diffs for significant modifications]

### Test Coverage

- Test files modified: X
- New tests added: ~Y

Output Guidelines

Commit Messages

• Show short hash (7 chars)
• Show first line of commit message only
• Truncate long messages to 80 chars
• Group by author if multiple contributors

File Paths

• Use relative paths from repo root
• Format as code: path/to/file.kt
• Include line change magnitude: (+X -Y)
• Highlight file type (source, test, config)

Statistics

Present in clear tables:

| Metric        | Count |
| ------------- | ----- |
| Commits       | 15    |
| Files Changed | 23    |
| Insertions    | +450  |
| Deletions     | -180  |

Diffs

• Include file path as header: ### path/to/file.kt
• Use code blocks with syntax highlighting
• Show context lines (git default: 3 lines before/after)
• Truncate very large diffs (>200 lines) with summary

Context Budget Management

Monitor diff sizes:

• Small session (<10 files, <500 lines): Safe for detailed mode
• Medium session (10-30 files, 500-2000 lines): Use selective diffs
• Large session (>30 files, >2000 lines): Concise mode with warnings

Progressive disclosure:

1. Always start with concise summary
2. Ask user: "Would you like detailed diffs for specific files?"
3. Generate diffs on demand rather than upfront

Fallback for large sessions: "This session modified 45 files with 5000+ line changes. Showing concise summary. Request specific files or modules for detailed diffs."

Anti-Patterns to Avoid

Don't:

• Generate diffs for all files in large sessions (context overflow)
• Include full diffs without asking (waste context on unneeded details)
• Ignore file types (treat test changes same as source changes)
• Lose context on what user wants to know
• Use generic summaries ("modified 10 files") without specifics

Do:

• Ask user what level of detail they need
• Prioritize key files by change magnitude
• Categorize files (source, test, config, docs)
• Provide actionable summaries
• Offer to drill down on specific files

Success Criteria

A good git session analysis should:

1. Inform: User understands scope of changes at a glance
2. Focus: Highlights most significant changes first
3. Actionable: Provides paths and diffs for deeper review
4. Efficient: Doesn't waste context on unnecessary details
5. Adaptable: Adjusts depth based on session size and user needs

Example Outputs

See contexts/example-outputs.md for detailed examples of concise summaries and code review formats.