new-feature

Create isolated Git worktrees with their own ports, database names, and setup commands. Work on a feature, merge it, then remove its worktree and resources.

Install

Install Python 3.13 or newer, Git, and uv, then install new-feature:

uv tool install new-feature

To configure your repository with a coding agent, install Codex or Claude Code and make its executable available on PATH. From your checkout, start setup:

new-feature setup --agent codex

The agent inspects the project and asks for approval before changing configuration or installing optional hooks. Run setup again to review an existing integration. You can also configure the tool yourself.

Usage

Start from a repository with at least one commit:

new-feature my-feature --no-agent
cd .worktrees/my-feature
# Edit and commit your changes here.
cd ../..
new-feature merge my-feature
new-feature teardown my-feature

Run lifecycle commands from the original checkout or a managed feature worktree. Commands use the owning checkout's configuration and manifest. Ordinary linked worktrees keep their own lifecycle state unless a manifest explicitly manages them. Use feature worktrees for edits and commits. If you're already in a coding agent session, use the printed absolute worktree path for the agent's tools.

To launch an agent in the worktree, use new-feature my-feature --agent claude. Without --agent, creation uses default_agent if configured. Use --no-agent to suppress it, including when you're already in an agent session.

new-feature NAME is shorthand for new-feature create NAME. Replace NAME with your feature name. Names become branch and directory slugs. Use explicit create when the name matches a command, such as new-feature create setup.

Inspect features, check their state, or get command help:

new-feature list
new-feature doctor
new-feature doctor --repair
new-feature create my-feature --dry-run
new-feature COMMAND --help

Replace COMMAND with a command name. Dry runs print environment values without creating a worktree or reserving values.

Project configuration

All settings are optional. Put shared settings in .new-feature.toml:

target_branch = "main"
setup = ["uv sync"]
pre_merge = ["uv run pytest"]
post_merge = ["uv run pytest"]
teardown = []

[env]
WEB_PORT = { allocate = "port", min = 3000, max = 3999 }
WORKER_ID = { allocate = "integer", min = 1, max = 15 }
DATABASE_NAME = { allocate = "name", prefix = "myapp", max_length = 63 }
CACHE_NAMESPACE = { allocate = "slug", prefix = "myapp" }
CACHE_DIR = { allocate = "path", base = ".new-feature/cache" }
APP_ENV = { value = "development" }

target_branch is the branch features start from and merge into. Keep personal preferences in the ignored .new-feature.local.toml:

default_agent = "codex"
pull_before_create = true
push = true
agents = { custom = ["custom-agent", "--prompt"] }

Configuration loads in this order, with later sources overriding earlier ones:

1. ~/.config/new-feature/config.toml, which accepts only default_agent. If you set XDG_CONFIG_HOME, its path is $XDG_CONFIG_HOME/new-feature/config.toml.
2. .new-feature.toml, or [tool.new-feature] in pyproject.toml if .new-feature.toml is absent.
3. .new-feature.local.toml, which also works on its own.

Local values and command lists replace shared values. Entries in agents and env override by name. In pyproject.toml, use [tool.new-feature.env] instead of [env]. You can also put agent, pull, and push preferences in shared configuration as repository defaults.

By default, new-feature uses main as the target branch, launches no agent, skips pull and push, and runs no commands or allocations. With pull_before_create = true, it fast-forwards the clean target checkout using its upstream. With push = true, it pushes the merged target branch to origin.

Codex and Claude have built-in aliases, which agents can add to or override. --agent accepts a configured name or an executable command, such as --agent "custom-agent --prompt", parsed without a shell. The generated prompt is the final argument. Override it with create_prompt or setup_prompt in configuration, or --prompt for one invocation.

Lifecycle commands run sequentially in a shell. setup, pre_merge, and teardown run in the feature worktree. post_merge runs in the original checkout before committing. A nonzero exit stops the operation.

Commands and launched agents receive allocated values plus NEW_FEATURE_NAME, NEW_FEATURE_SLUG, NEW_FEATURE_BRANCH, NEW_FEATURE_WORKTREE, and NEW_FEATURE_REPO_ROOT. Existing shells and agent sessions don't inherit these values. Run manual commands with new-feature exec NAME -- COMMAND ... to restore the recorded environment and working directory, for example new-feature exec my-feature -- uv run pytest. Names normalize to exact slugs; partial matches are rejected. Standard input, output, and errors are inherited, and the child's exit code is returned (128 + signal for signal termination). Arguments run without a shell; use sh -c explicitly for shell expansion or pipelines.

Multiple exec commands can run in one feature, such as a server and its tests. Creation, merge, teardown, and repair of that feature are refused while an exec command runs. Interrupted commands terminate their process group.

Port reservations span all port variables in this repository. Availability checks don't hold ports open or reserve them against other repositories or programs. Integer reservations are per variable. Without explicit bounds, ports use 1024-65535 and integers use 0-65535.

Use name for database identifiers, with max_length set to your database's identifier length limit. Use slug for readable namespaces in the form prefix-feature-slug. Paths return base/feature-slug without creating directories. Relative paths resolve from the command's working directory.

Lifecycle

Creating an active feature again reuses its worktree and environment without rerunning setup. If setup fails, new-feature attempts cleanup. If cleanup fails or doctor reports setup-incomplete, save needed work, then tear down and recreate the feature.

The new-feature merge NAME command requires clean feature and target checkouts and refuses merge conflicts. Failed merges attempt to restore the target checkout and remove non-ignored untracked files created there. Rollback doesn't undo external effects such as database changes.

Merge-check failures print a log path under .new-feature/diagnostics/merge-failures/. If push fails, rerun merge to retry. Merge leaves the worktree in place. Run teardown afterward, before creating another feature with the same name.

Teardown runs your cleanup commands, then removes the worktree and branch. If cleanup fails, removal stops even with --force. Use --force only to discard uncommitted or unmerged work deliberately, or bypass process protection. If the feature record is missing, teardown skips configured cleanup and can still remove the worktree.

Use new-feature teardown NAME --dry-run to preview the absolute worktree path, branch, target, cleanup commands, removal actions, and refusal reasons. Preview exits 1 when preflight refuses teardown and 0 otherwise. It runs no cleanup and creates no lock files or reservations. Concurrent changes can invalidate its snapshot, and preview cannot predict cleanup failure. --force --dry-run previews forced removal; cleanup failure still stops real removal.

On Linux, teardown also refuses processes owned by your user whose working directory is the worktree or a directory beneath it. It checks before cleanup and again immediately before removal. Stop those processes or use --force, which bypasses this check without stopping them. Process protection is best effort: it skips processes that disappear or have unreadable /proc/PID/cwd, does not find processes that only hold open files or work elsewhere, and cannot prevent processes entering the worktree after the scan. An unavailable /proc scan refuses teardown unless --force is supplied.

If you tear down the worktree containing your shell's current directory, change back to the original checkout afterward; a CLI cannot move its parent shell.

Teardown accepts patch-equivalent branches, whose patches already exist in the target, except branches with unmerged merge commits.

Use new-feature doctor --repair to clean up stale feature records and branches whose worktrees no longer exist. Repair preserves unmerged work and unreadable worktrees. It doesn't recreate missing worktrees. Doctor exits nonzero while issues remain.

list --json (also status --json) and doctor --json emit one JSON document on stdout. Diagnostics remain on stderr. schema_version is 1; successful reports contain command (list or doctor), ok, and a features array sorted by slug. List's ok means inspection succeeded; doctor's ok means no feature has remaining issues. Each feature includes name, slug, branch, target_branch, absolute worktree, lifecycle status, human state, issues, worktree_exists, branch_exists, clean, integration, config_drift, setup_incomplete, and worktree_error. clean and integration are null when unavailable; worktree_error is null when inspection succeeds. Integration is merged, patch-equivalent, or unmerged. Lifecycle status is initializing, active, or merged. Issue labels are setup-incomplete, missing-worktree, worktree-error, missing-branch, dirty, unmerged, and config-drift. Allocated environment values are omitted.

Doctor also includes repairs, an array of {"slug": "...", "message": "..."}. doctor --repair --json reports remaining features after repair. Expected command failures emit {"schema_version": 1, "error": {"code": "command-failed", "message": "..."}} and exit 1. Invalid inspection arguments with --json emit the same error envelope with code invalid-arguments and exit 2. Doctor still exits 1 while reported issues remain. Treat documented field names, issue labels, and error codes as stable within schema version 1; accept additional fields and inspect issues and integration instead of parsing human state or messages.

Setup and creation ignore .new-feature/, .worktrees/, and *.local.toml locally without changing your tracked .gitignore file.

Agent guards

Install optional hooks to keep coding agents on feature branches and require new-feature for worktree creation, removal, and merging into the target branch:

new-feature install-rules           # tracked .i-insist/new-feature.toml
new-feature install-rules --global  # ~/.i-insist/new-feature.toml

The installer also sets up i-insist. Restart your coding agent and review /hooks after installation. Reinstalling replaces generated rule files, so leave them unmodified.

If a guard blocks an action, follow its error message. To approve an override, include I insist in a human message.