jj-hunk Skill | Agent Skills

jj-hunk

Programmatic hunk selection for Jujutsu. Split, commit, or squash specific hunks without interactive prompts.

Quick Start

# List hunks in current changes
jj-hunk list

# List hunks for a specific revision
jj-hunk list --rev @-

# Split hunks 0,1 of foo.rs into first commit, rest into second
jj-hunk split '{"files": {"src/foo.rs": {"hunks": [0, 1]}}, "default": "reset"}' "first commit"

Commands

| Command | Description | | ----------------------------------------- | ------------------------------------ | | jj-hunk list [options] | List hunks, files, or spec templates | | jj-hunk split [-r rev] <spec> <message> | Split changes into two commits | | jj-hunk commit <spec> <message> | Commit selected hunks | | jj-hunk squash [-r rev] <spec> | Squash selected hunks into parent |

List Options

| Option | Description | | --------------------------------------- | ------------------------------------- | | --rev <revset> | Diff revision against parent | | --format json\|yaml\|text | Output format (default: json) | | --include <glob> / --exclude <glob> | Filter paths (repeatable) | | --group none\|directory\|extension | Group output | | --files | List files with hunk counts only | | --spec-template | Emit a spec template (JSON/YAML only) |

Spec Format

Specs are JSON or YAML. Select hunks by index (0-based) or by stable ids.

{
  "files": {
    "path/to/file": { "hunks": [0, 1] },
    "path/to/other": { "ids": ["hunk-9a2b..."] },
    "path/to/another": { "action": "keep" },
    "path/to/skip": { "action": "reset" }
  },
  "default": "reset"
}

| Action | Description | | ----------------------- | --------------------------------------- | | {"hunks": [0, 1]} | Select by index (0-based) | | {"ids": ["hunk-..."]} | Select by stable ID from jj-hunk list | | {"action": "keep"} | Keep all changes in file | | {"action": "reset"} | Discard all changes in file | | "default" | Action for unlisted files |

Example: Split by Hunk

Scenario: You have multiple changes in one commit. Split them logically.

# 1. See what hunks exist
jj-hunk list --format text

Output:

M src/main.rs
  hunk 0 insert hunk-abc123 (before 1+0 after 1+10)
  hunk 1 insert hunk-def456 (before 1+0 after 1+5)
M src/lib.rs
  hunk 0 insert hunk-789xyz (before 1+0 after 1+8)

# 2. Split: first hunk of main.rs → commit A, rest → commit B
jj-hunk split '{"files": {"src/main.rs": {"hunks": [0]}}, "default": "reset"}' "feat: add feature A"

# 3. The remaining changes stay in working copy
jj diff --name-only
# src/main.rs (hunk 1), src/lib.rs

Example: Split Multiple Files

# List hunks
jj-hunk list --format yaml

# Create spec file
cat > /tmp/split-spec.yaml << 'EOF'
files:
  pkgs/new-tool.nix:
    action: keep
  modules/home-manager/packages/cli.nix:
    hunks: [0]
  flake.nix:
    hunks: [0]
default: reset
EOF

# Split using spec file
jj-hunk split --spec-file /tmp/split-spec.yaml "feat(cli): add new-tool"

Example: Commit Subset of Changes

# Commit only the fix, leave experimental code uncommitted
jj-hunk commit '{"files": {"src/fix.rs": {"action": "keep"}}, "default": "reset"}' "fix: handle edge case"

Example: Squash Specific Changes

# Squash cleanup into parent commit
jj-hunk squash '{"files": {"src/cleanup.rs": {"action": "keep"}}, "default": "reset"}'

Example: Split by File Pattern

# Commit all test files, keep source changes
jj-hunk commit '{"files": {}, "default": "reset"}' "test: add tests"
# Then filter with --include
jj-hunk list --include '**/*.test.rs' --format yaml

Tips

Use --spec-template to generate an ID-based spec:

jj-hunk list --spec-template --format yaml > /tmp/spec.yaml

IDs are stable (sha256-based), indices are not
Use --files for a quick summary:
```
jj-hunk list --files --format text
```

Read spec from stdin:

cat spec.json | jj-hunk commit - "message"

Related Skills

jujutsu: General jj commands and workflows
conventional-commits: Commit message format

Agent Skills: jj-hunk

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