Worktree setup

Worktree Setup

Set up isolated git worktree(s) for a task, deciding single vs dual/multi repo scope from the nature of the change, using a per-project config. Setup only — creates worktree(s) + branch(es), copies env, installs deps, registers the primary worktree, then hands back. It does NOT plan or implement.

REQUIRED BACKGROUND: Read the underlying git-worktree isolation logic for your toolchain. This skill layers per-project config (base branch, install, env-copy, coupling) on top.

Paths: scripts live at ${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/scripts/. Persistent per-project configs live at ${CLAUDE_PLUGIN_DATA}/projects/ (survives plugin updates), overridable with WORKTREE_REGISTRY_DIR. A bundled projects/example.json documents the format.

When to trigger

• "set up a worktree for <X>" · "start a worktree for this task" · /skills:worktree-setup <task>
• "isolate this work in a worktree" (inside a configured repo)
• Before a subagent-driven-development / executing-plans run on a repo not already in a linked worktree

When NOT to trigger

• No config matches the current repo and the user did not ask to set one up → no-op (offer init).
• Already in a linked worktree (GIT_DIR != GIT_COMMON) → work in the one you're in.
• Trivial one-file fix the user wants in place (git switch -c fix/<slug>) → no worktree.

Step 0 — Resolve config (always first)

node "${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/scripts/resolve-config.mjs" resolve

Returns JSON: {status} is one of in-repo | registry | none | ambiguous.

• in-repo / registry → use configPath. Continue.
• none → the repo isn't configured. If the user asked to set up a worktree, go to Init (Step I). Otherwise no-op.
• ambiguous → two registry configs match this origin; show candidates and ask which (or fix the remoteMatch values).

Also confirm you are NOT already in a linked worktree:

GIT_DIR=$(cd "$(git rev-parse --git-dir)" && pwd -P)
GIT_COMMON=$(cd "$(git rev-parse --git-common-dir)" && pwd -P)
[ "$GIT_DIR" = "$GIT_COMMON" ] || { echo "already in a linked worktree — no-op"; }

The current repo's key = the repos[].dir whose value equals basename of the current git toplevel.

Step 1 — Decide scope (single vs dual/multi)

This is the skill's core judgment. Read the config's coupling[], neverCouple, and notes.

1. Read the task. If it clearly belongs to one repo's domain → single (that repo).
2. Does it touch a declared shared surface? Compare the task against each coupling[].sharedSurface. If yes → dual/multi: all repos in that coupling group, identical branch, primary = the repo the task originates in.
3. Unsure? Grep the coupling[].grep globs (and contractPath if set) in the sibling repo for the symbols/files involved before deciding.
4. neverCouple repos are always single. If a change elsewhere affects a surface they also use, surface it as a manual follow-up — never auto-create their worktree.
5. Respect the per-coupling notes (e.g. code paths that are live on only one side).

Step 2 — Confirm before creating

Worktrees are heavy (install takes minutes). Present the plan and get a yes:

Plan: dual worktrees (shared contract change).

• Primary: <dir> → feature/<slug> (becomes the working dir)
• Secondary: <dir> → feature/<slug> (edit via absolute path)
• Base: origin/<base> · install + env-copy in both Create these?

Branch: use the user's, else propose <prefix>/<kebab-slug> from branchPrefixes. On dual/multi the branch name is IDENTICAL across repos.

Step 3 — Create the worktree(s)

Run the engine once per target repo, primary first:

"${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/scripts/new-worktree.sh" --config <configPath> --repo <key> --branch <name>

Flags: --no-install, --no-env, --base <branch>, --slug, --worktree <path>, --parent <dir>, --help.

The engine cuts from origin/<base> (never disturbs the main checkout), --unset-upstreams, copies configured env files, runs the configured install, prints a report. For dual/multi, run it once per repo with the same --branch.

Step 4 — Register the primary worktree (agentic sessions)

EnterWorktree(path="<absolute path to PRIMARY worktree>")

Binds the session to the primary worktree. Secondaries are NOT entered — operate on them via absolute paths so coupled contracts stay in sync. If EnterWorktree isn't available, the user can cd in from a terminal.

Step 5 — Verify & report

Check	Command	Expected
Worktree(s) exist	git -C <main-checkout> worktree list	a row per new worktree
HEAD is new branch	git -C <wt> branch --show-current	the branch name
No upstream	git -C <wt> rev-parse --abbrev-ref --symbolic-full-name '@{u}'	fatal: no upstream (intended)
Main checkout untouched	main checkout's branch --show-current	unchanged
Deps installed	ls <wt>/node_modules (or stack equivalent)	present (unless --no-install)
Session cwd (agentic)	pwd after EnterWorktree	the primary worktree

Report each worktree path, branch + base SHA, env/install status, which is primary/cwd, and (dual) the absolute-path reminder. Then surface the config's caveats. Hand back.

Step I — Init a new project's config

When resolve returns none and the user wants a worktree here:

1. Detect sibling repos under the parent dir and their origin URLs.
2. Base branch: git symbolic-ref refs/remotes/origin/HEAD (fallback: develop if it exists, else main).
3. Install command from lockfile: bun.lock/bun.lockb→bun install; pnpm-lock.yaml→pnpm install; yarn.lock→yarn; package-lock.json→npm install; pubspec.yaml (+.fvmrc)→fvm install && fvm flutter pub get; Cargo.toml→cargo fetch; go.mod→go mod download.
4. Coupling: read the repo's CLAUDE.md/docs for cross-repo agreements; ask the user what shared surface couples which repos (and where the contract lives).
5. All detections are suggestions — confirm with the user.
6. Write the config against ${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/references/worktree.schema.json (see projects/example.json for a worked sample):
   • single-repo project → in-repo <toplevel>/.worktree.json (recommended where committing is fine).
   • multi-repo project → ${CLAUDE_PLUGIN_DATA}/projects/<name>.json (persists across plugin updates; do NOT write into the plugin's own dir, which is wiped on update). WORKTREE_REGISTRY_DIR overrides the location.

Red flags — never do these

• Switch the main checkout's branch. The engine cuts from origin/<base> precisely to avoid this.
• Cut from main when the project's base is develop. Use the config's base.
• Auto-create a second worktree for a change that doesn't touch a declared shared surface.
• Auto-create a neverCouple repo's worktree as a "sync" — surface overlap as a manual note.
• Place a worktree inside an existing checkout — always a sibling dir.
• Skip --unset-upstream (the engine does it) — otherwise a later git pull merges base into the feature branch.
• Write configs into ${CLAUDE_PLUGIN_ROOT} — that dir is ephemeral across updates; use ${CLAUDE_PLUGIN_DATA} or an in-repo .worktree.json.

Worked examples

Assume a registry config at ${CLAUDE_PLUGIN_DATA}/projects/myapp.json describing two coupled repos (api, web) — see projects/example.json for the full shape.

Single (backend-internal): "worktree for the pricing-rounding refactor" (no response-shape change) →

"${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/scripts/new-worktree.sh" --config "${CLAUDE_PLUGIN_DATA}/projects/myapp.json" --repo api --branch fix/pricing-rounding

then EnterWorktree(path=".../myapp-api-pricing-rounding").

Dual (API contract change): "add a note field to items and show it in the web app" (request + response shape changes → web reads it) →

"${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/scripts/new-worktree.sh" --config "${CLAUDE_PLUGIN_DATA}/projects/myapp.json" --repo api --branch feature/item-note
"${CLAUDE_PLUGIN_ROOT}/skills/worktree-setup/scripts/new-worktree.sh" --config "${CLAUDE_PLUGIN_DATA}/projects/myapp.json" --repo web --branch feature/item-note

primary = myapp-api; edit myapp-web via absolute paths; update the API contract source of truth.

Init (new project): "set up a worktree here" in an unconfigured repo → run Step I, detect repos/base/install, confirm, write .worktree.json (single) or ${CLAUDE_PLUGIN_DATA}/projects/<name>.json (multi), then proceed from Step 1.