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

Determine range type:

• Time-based: Parse relative or absolute time

• Commit-based: Validate commit references exist

• Branch-based: Resolve branch names to commits

Validate git repository:

git rev-parse --git-dir

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:

• Large changes (>100 lines modified): Always include

• New files: Include (especially if >50 lines)

• Deleted files: Note but don't diff

• Architecture files: build.gradle.kts , AndroidManifest.xml , module configs

• 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:

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:

• Always start with concise summary

• Ask user: "Would you like detailed diffs for specific files?"

• 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:

• Inform: User understands scope of changes at a glance

• Focus: Highlights most significant changes first

• Actionable: Provides paths and diffs for deeper review

• Efficient: Doesn't waste context on unnecessary details

• 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.