craft:workspace

Preamble (always runs — non-overridable)

1. "${CRAFT_ROOT:-${CLAUDE_PLUGIN_ROOT}}/scripts/manifest-lint.sh" must pass; read the manifest.
2. Probe: git repo present (else STOP — craft needs one); default branch (origin/HEAD → main → master → ask once).
3. Memory read/write surface (advisory). READS: last toolchain entry for this repo (ecosystem + lockfile fingerprint). If the fingerprint matches the current lockfile, skip re-detection for the already-known ecosystem — still re-detect on a miss or a changed fingerprint. WRITES (appended to the run record as produced; saved to the store once at Done): the detected ecosystem + lockfile fingerprint produced by scripts/worktree-setup.sh lockfile detection. The hint never gates — a miss falls through to full detection.

Procedure (default body — a manifest override: replaces everything below)

1. Infer the branch type from the brief (feat/fix/chore, default feat).
2. Consult isolate action (default always, ADR-127 — proceeds silently unless policy forbids it; see docs/contributing/specs/policy.md for surface semantics). Then, strategy worktree (default), as one Bash call — a compaction cannot split the two:

   git worktree add ../<repo>-<slug> -b <type>/<slug> && \
   "${CRAFT_ROOT:-${CLAUDE_PLUGIN_ROOT}}/scripts/worktree-setup.sh" <abs-worktree-path> [manifest scripts.post-setup]

   The run ledger stays where §0 opened it, in the git common dir: nothing moves. Strategy in-place (manifest workspace: { strategy: in-place }): create the branch in the current checkout (git switch -c <type>/<slug>); deps assumed present or installed in place; later phases use the checkout root wherever they'd use the worktree (the run-lock path resolves from it too). In a Claude Code background session (CLAUDE_JOB_DIR set) → STOP before git switch: the Bash call that would run it tests [ -n "${CLAUDE_JOB_DIR:-}" ] first. The session's edit guard refuses Write/Edit in the shared checkout until the session isolates (worktree.bgIsolation), so an in-place run could not edit. Reason: in-place strategy cannot run in a background session; use strategy worktree or run attended. The STOP holds even where a repo turned worktree.bgIsolation off: Craft does not read that setting, because it merges across the user, project, local, managed and --settings layers, so the session's effective value is not observable from the run. Nothing was switched, so nothing needs undoing.
3. Branch or worktree path collision → STOP and ask; never reuse silently.
4. Apply the manifest's global/workspace context: file now: perform any tooling activation it declares (the session does this — agents will receive the same file and must find the tooling already active). Its teardown counterpart runs at integrate.
5. All subsequent work happens ONLY in this worktree/branch, reached by its absolute path: Bash as cd <abs-worktree-path> && …, file tools at <abs-worktree-path>/…, agents spawned with it as their working directory. Never move the session itself with a working-directory relocation tool (Claude Code's EnterWorktree): for a worktree outside .claude/worktrees/ it raises a permission prompt that auto mode cannot approve, which halts a background session, and a background session's edit guard already accepts edits at the worktree's absolute path.