feat: Add configurable stats mode with Git integration

[krfantasy]

Summary

Introduces a new stats mode output option that provides concise change statistics instead of full tree diffs, along with automated Git integration for .als files.

Motivation

Current limitations:

• Tree mode output can be overwhelming for large Ableton Live projects with many tracks/devices
• Git integration for .als files requires manual configuration of .gitattributes
• Commit messages for .als changes must be manually written or copy-pasted from diff output
• Stats types were hardcoded in the renderer with no user customization

What this PR solves:

• Provides a quick overview of changes without full detail
• Automates Git integration with an interactive setup script
• Auto-generates commit message summaries from .als changes
• Makes stats mode fully configurable via existing config system

Changes Overview

🆕 New Stats Mode

• New module: lib/output/stats_renderer.ml (84 lines)
• New flag: --mode stats
• New tests: test/test_stats_renderer.ml (165 lines, 8 tests)

Example output:

Tracks: 2 Added, 1 Removed, 5 Modified
Devices: 3 Added, 0 Removed, 2 Modified
Clips: 8 Added, 2 Removed, 1 Modified

⚙️ Configurable Type Filtering

Refactored from hardcoded reportable_types list to config-driven filtering via get_effective_detail()

Added stats_default preset in lib/output/config.ml with 7 historically tracked types:

• LiveSet, Track, Device, Clip, Note, Automation, Mixer, Routing, Locator

🐙 Automated Git Integration

New script: scripts/setup-git.sh (111 lines)

Features:

• Prerequisite checks (alsdiff in PATH, git repository)
• Automatic .gitattributes configuration for .als files
• Interactive prompt for custom command line arguments
• Optional prepare-commit-msg hook installation

📝 Prepare-commit-msg Hook

Auto-generates commit message summaries using alsdiff --mode stats on staged .als files

🔧 Code Refactoring

• Moved: render_views from bin/alsdiff.ml → lib/output/text_renderer.ml
• Extracted: build_base_renderer_config() helper to eliminate duplicate config building logic

Files Changed

File	Changes
bin/alsdiff.ml	Main entry point - mode handling
lib/output/config.ml	Added stats_default preset
lib/output/stats_renderer.ml	New stats renderer module
lib/output/text_renderer.ml	Moved render_views function
scripts/setup-git.sh	Git integration setup script
test/test_stats_renderer.ml	Comprehensive test suite

Total: 8 files changed, 527 insertions(+), 80 deletions(-)

Usage Examples

# Stats mode
alsdiff --mode stats old.als new.als

# With custom config
alsdiff --mode stats --config project-config.json old.als new.als

# Git integration
./scripts/setup-git.sh
git diff song.als

# Commit with auto-generated message
git add song.als
git commit  # Hook auto-generates stats summary

Testing

✅ All tests pass: 8 new tests + existing tests unaffected

Backwards Compatibility

✅ No breaking changes: Tree mode remains default, new --mode flag is optional

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Return git-mode argument errors with exit code 2

This branch returns 1 for a stats-mode argument error even when --git is active, which makes Git (trustExitCode) interpret the failure as "differences found" instead of an invalid invocation. In practice, alsdiff --git --mode stats --prefix-added ... will look like a real diff result rather than a configuration error, despite the command documentation in this file defining exit code 2 for invalid arguments. Return 2 in git mode for this path so misconfiguration is surfaced correctly.

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[chatgpt-codex-connector]

Handle renamed .als files in commit-message hook

The generated hook only branches on M, A, and D, but git diff --cached --name-status can emit rename/copy statuses (for example R100\told.als\tnew.als). Those entries currently fall through and produce no summary text, so commits that rename .als files silently miss stats output for those changes. Add handling for R* (and ideally C*) statuses so commit summaries cover all staged .als changes.

Useful? React with 👍 / 👎.