Feature work happens in a worktree

master is the checkout the live bridge runs from. Work there and a half-built feature is one mystical restart away from being the thing the user is talking to. One-file fix or doc tweak: master is fine. Anything else: worktree.

Create it where the dashboard can see it

git worktree add -b feat/x ~/projects/.worktrees/mystical-assistant/feat-x

Inside BASE_PATH is the load-bearing part — _abs_within() drops any tree outside ~/projects, so a worktree in /tmp is invisible to every surface and no session can start in it. Git resolves branch→tree, so a hand-made git worktree add elsewhere under ~/projects still attaches; .worktrees/<repo>/<branch> (slashes to dashes, _worktree_path() in bridge/dashboard/server.py) is the convention that keeps it out of the project browser.

What isn't in there

git worktree add checks out tracked files only, so everything git-ignored is missing:

• .env — cp ~/projects/mystical-assistant/.env <wt>/.env. Without it bin/mystical dies on any command except build/doctor.
• node_modules — only if you must build web in the worktree: cd <wt>/bridge/dashboard/web && npm ci. Usually you don't; build from master at ship time instead.

New data goes in a scratch DB

config.BRIDGE_DB defaults to ~/.bridge_state/bridge.db — the live bridge's sessions, turns and events. A worktree that migrates it or writes new-shape rows damages the thing the user is working in right now.

• Tests need nothing. tests/conftest.py already pins BRIDGE_DB to a temp file before config is imported.
• Any manual script or REPL: BRIDGE_DB=/tmp/wt-x.db python3 …. In the environment, before the process starts — bridge/config.py freezes the value at import, so setting it afterwards does nothing.
• Schema changes stay in bridge/store.py: a line in _SCHEMA plus an idempotent ALTER TABLE in init(), like every column already there. Additive only — master's code keeps reading that DB.

Two traps

• mystical on PATH is the main checkout. It's a symlink to mystical-assistant/bin/mystical, and that script resolves REPO from its own location. mystical restart inside a worktree restarts the live bridge running master's code. Say <wt>/bin/mystical when you mean the worktree.
• Worktree code is never live. It can't be, until it's merged and the bridge restarts — see bridge-ship. Don't restart anything to "test" it.

Fold back

git -C ~/projects/mystical-assistant merge feat/x
git worktree remove ~/projects/.worktrees/mystical-assistant/feat-x

Then bridge-ship. Abandoned worktrees aren't free: each one is a dirty tree NEXT UP keeps suggesting and a row in the WORKTREES tab, and each can hold one of the 8 dev-server slots (devserver.MAX_SERVERS).