GitHub - ThatXliner/gah: Git Add Hunk, built for agents to use

gah - Git Add Hunks

Non-interactive hunk-based staging for git. Stage specific hunks by index, content anchor, regex, or line range—no interactive prompts required. Split hunks into smaller pieces and stage individual changed lines, the non-interactive equivalent of git add -p's split and edit modes.

The Problem

git add -p is great for selective staging, but it requires interactive stdin. That makes it unusable for:

AI coding agents (Claude, Copilot, Cursor) that can't interact with prompts
Scripts and automation that need deterministic staging
Remote/headless environments where interactive TTY isn't available

Installation

CLI

Claude Code

Install the CLI above, then:

/plugin install ThatXliner/gah

Or manually:

mkdir -p .claude/skills
git clone https://github.com/ThatXliner/gah.git .claude/skills/gah

Claude Code will auto-use gah for selective staging instead of git add -p.

Other AI Agents (Codex, Cursor, etc.)

Install the CLI, then add the skill instructions from skills/gah/SKILL.md to your agent's context.

Usage

Preview hunks

# Show hunks with indices
gah preview src/main.rs

# Preview all modified files
gah preview --all

# Machine-readable JSON output
gah preview src/main.rs --json

Output:

[1:Apparent] @@ -341,7 +341,8 @@ fn render_key_summary(
    context line
 + new line
 - old line
    context line

[2:Caption] @@ -363,7 +364,15 @@ fn render_binding_summary(
    ...

src/main.rs: 2 hunks

The word after the index is the anchor—a single-token content hash that stays stable even when line numbers shift. Anchors are chosen to be single tokens in common LLM tokenizers for maximum efficiency.

Stage by hunk index

# Stage specific hunks
gah add src/main.rs --hunks 1,3,5

# Stage a range
gah add src/main.rs --hunks 1-3,7

Stage by anchor (content hash)

Anchors are stable identifiers based on hunk content. Unlike indices, they don't change when other hunks are staged or when line numbers shift. Ideal for AI agents that preview once, then stage later.

# Stage by full or partial anchor
gah add src/main.rs --anchor Apparent
gah add src/main.rs -a App      # prefix match works

Stage by regex

# Stage hunks containing a pattern
gah add src/main.rs --grep "TODO"

# Exclude hunks matching a pattern
gah add src/main.rs --grep "debug" --invert

Stage by line range (partial hunks)

--lines stages only the changed lines within the given working-tree range, trimming each matched hunk down to that range. Additions outside the range are dropped; deletions outside the range are left in place. This lets you stage a single changed line out of a larger block—something git add -p's split mode can't do for adjacent changes.

# Stage only the changes on lines 100-150 (working tree lines)
gah add src/main.rs --lines 100-150

# Stage one line out of a multi-line edit
gah add src/main.rs --lines 142

# Multiple ranges
gah add src/main.rs --lines 100-150,200-250

Split hunks into smaller pieces

By default git groups nearby changes into one hunk. --split re-diffs with zero context so each change becomes its own hunk, then you can preview or stage them independently.

# Preview the finest-grained hunks
gah preview src/main.rs --split

# Stage one of the split-out changes by anchor
gah add src/main.rs --split --anchor Beast

Adjacent changed lines can't be separated by --split (git keeps them in one hunk even at zero context)—use --lines to pick individual lines out of such a block.

Stage by AST symbol (requires tree-sitter feature)

Stage hunks that touch specific functions, classes, or other code symbols using tree-sitter AST analysis.

# Install with tree-sitter support
cargo install gah --features tree-sitter

# Stage hunks touching a function
gah add app.py --symbol subtract

# Multiple symbols
gah add app.py --symbol subtract --symbol multiply

Supported languages: Python, JavaScript, TypeScript, Rust, Go.

Combine filters

gah add src/main.rs --grep "feature" --lines 300-500

Dry run

# See what would be staged without actually staging
gah add src/main.rs --hunks 1,3 --dry-run

JSON Output

Add --json for structured output:

gah preview src/main.rs --json

{
  "file": "src/main.rs",
  "hunks": [
    {
      "index": 1,
      "anchor": "Apparent",
      "header": "@@ -341,7 +341,8 @@",
      "old_start": 341,
      "old_count": 7,
      "new_start": 341,
      "new_count": 8,
      "content": "...",
      "function_context": "fn render_key_summary(",
      "additions": 1,
      "deletions": 0
    }
  ]
}

Why not just use...

git add -p — Requires interactive stdin. Can't be used programmatically.

git add -N + git add -p — Still requires interactive input.

git apply — Works, but you need to manually construct the patch. gah handles the patch construction for you.

Editor integrations — Great when available, but not always accessible to scripts or agents.

How it works

Runs git diff to get the current changes
Parses the diff into individual hunks
Filters hunks based on your criteria
Reconstructs a minimal patch for selected hunks
Applies via git apply --cached

License

MIT