speckit.start

Prompt file imported from UnderUndre/unet-legacy (.github/prompts/speckit.start.prompt.md). Fill in {{arguments}}, {{N}}, {{slug}} before use. Copyright stays with the author.

agent: speckit.start

User Input

{{arguments}}

Required argument: <feature-description> — same input you'd pass to /speckit.specify. Used to derive the slug.

Goal

ultrathink

"Каждый стояк в свою шахту. Иначе один сорвёт — все потечёт." — Valera, on isolation.

Many SpecKit pipelines run in parallel (multiple features in flight, multi-AI review fan-out). Without explicit worktree isolation, two sessions can stomp on each other's specs/<N>-<slug>/ directory, run /speckit.implement against a half-formed plan, or push commits onto the wrong branch.

/speckit.start is the new canonical entry point for a feature. It does what /speckit.specify step 2 used to do (branch + numbering) before any LLM work begins, in an explicit isolated worktree, so the rest of the pipeline can assume clean state.

Operating Constraints

Modifies the file system and git state:

• Creates a worktree at .claude/worktrees/<N>-<slug>/.
• Creates a new branch feature/<N>-<slug> from main (or current default branch).
• Initializes empty specs/<N>-<slug>/ directory inside the worktree.

Does NOT invoke any LLM-driven step (no spec.md generation). That's /speckit.specify's job.

Execution Steps

1. Generate Slug

Same logic as /speckit.specify step 1:

• Analyze {{arguments}} (feature description), extract meaningful keywords.
• 2-4 words, action-noun format, preserve technical terms.
• Examples:
  • "Add user authentication" → user-auth
  • "Implement OAuth2 for the API" → oauth2-api
  • "Cross-AI review pipeline" → cross-ai-review

Abort with usage if {{arguments}} is empty: "Provide a feature description, e.g., /speckit.start cross-AI review pipeline."

2. Determine Next Feature Number

Acquire a numbering lock to avoid races between parallel /speckit.start sessions:

mkdir -p .specify && exec 9>.specify/.lock || { echo "Another /speckit.start is running."; exit 1; }
flock -n 9 || { echo "Lock held — another /speckit.start in progress."; exit 1; }

Inside the lock:

• git fetch --all --prune (avoid stale remote view).
• Scan three sources for highest existing number:
  • Remote branches: git ls-remote --heads origin | grep -E 'refs/heads/feature/[0-9]+-'
  • Local branches: git branch | grep -E '^[* ]*feature/[0-9]+-'
  • Specs directories: ls specs/ | grep -E '^[0-9]+-'
• N = max(existing) + 1, zero-padded to 3 digits (001, 002, …).

Release lock at end of step (close fd 9).

3. Create Worktree + Branch

git worktree add ".claude/worktrees/{{N}}-{{slug}}" -b "feature/{{N}}-{{slug}}"

If .claude/worktrees/ doesn't exist, create it first. The branch is created from the current HEAD of the default branch (main or whatever is configured).

4. Initialize Feature Directory

Inside the new worktree:

mkdir -p "specs/{{N}}-{{slug}}"

Do not create spec.md yet — that's /speckit.specify's output.

5. Report to User

Print:

✓ Feature 042-cross-ai-review started
  Branch:   feature/042-cross-ai-review
  Worktree: .claude/worktrees/042-cross-ai-review/
  Spec dir: specs/042-cross-ai-review/

Next steps:
  cd .claude/worktrees/042-cross-ai-review
  /speckit.specify <description>

Coordination with /speckit.specify

/speckit.specify MUST detect when it's running inside .claude/worktrees/<N>-<slug>/ (cwd path matches that pattern) and skip its own step 2 (branch + numbering), reusing the worktree's state.

If /speckit.specify is invoked WITHOUT a prior /speckit.start (legacy direct invocation), it falls back to its own step 2 — backward-compatible.

Operating Principles

Lock-then-fetch

Numbering races are real when two sessions start within seconds. The flock on .specify/.lock is cheap insurance. Stale lock recovery: if .specify/.lock exists but no /speckit.start is actually running, delete it manually.

Worktree, not branch-switch

Don't git checkout to switch — that mutates the current working directory and surprises any concurrent session. git worktree add keeps each feature physically isolated.

Idempotent

If .claude/worktrees/<N>-<slug>/ already exists, abort with: "Feature already started. Use that worktree, or remove it via git worktree remove." Don't silently re-init.

Context

{{arguments}}