HARD GATE — Direct Git work on main/master or reuse of an unrelated Jujutsu change is prohibited. Create a feature branch/worktree or Jujutsu workspace/change.

HARD GATE — Do NOT proceed with development until Preflight passes on the default branch. Red Preflight blocks branch creation and all forward work — invoke quick-fix or fix-bug per CONVENTIONS § Discovered Defects.

Create an isolated Git worktree or Jujutsu workspace before code. Preflight must be green first — solo-default owns the whole tree.

Ask if not already known: “What’s the name of this feature or task?” Use it as the branch name slug (kebab-case, max 40 chars).

Read state.yaml vcs.kind. For jj, do not run the Git blocks below: verify with jj status and jj log -r '::@' -n 5, create isolation with jj workspace add ../<task-slug> -r @, then run jj -R ../<task-slug> describe -m "feat: <task>". Record the new stable change ID. For git, continue below.

HARD GATE — Git kickoff MUST start from an updated, clean default branch in the primary repository root (not a linked worktree).

# Detect default branch
DEFAULT=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@' || echo main)

git checkout "$DEFAULT"
git pull --ff-only origin "$DEFAULT"   # skip if no remote
git status                             # working tree MUST be clean
git log --oneline -5

Spec-only pre-kickoff — before enforcing the clean-tree gate, check whether dirty files are spec artifacts:

DIRTY=$(git status --porcelain | awk '{print $2}')
NON_SPEC=$(echo "$DIRTY" | grep -v '^specs/' || true)

if [ -z "$DIRTY" ]; then
  : # clean — proceed
elif [ -z "$NON_SPEC" ]; then
  # spec-only dirty tree — offer auto-commit
  echo "Dirty spec artifacts: $(echo $DIRTY | tr '\n' ' ')"
  read -p "Commit spec artifacts before kickoff? [Y/n]: " CONFIRM
  CONFIRM=${CONFIRM:-Y}
  if [[ "$CONFIRM" =~ ^[Yy] ]]; then
    git add specs/
    git commit -m "chore(state): checkpoint before kickoff"
  fi
else
  echo "Dirty tree: $NON_SPEC (not a spec artifact). Stash or commit before proceeding."
  exit 1
fi

• Spec artifacts match specs/ — state.yaml, epics YAMLs, execution-status.yaml, etc.
• Non-spec dirty files (src/, scripts/, SKILL.md, …) still enforce the full clean-tree gate.
• If not on $DEFAULT after checkout, stop and fix before continuing.

Before creating the worktree, verify the target environment is clean:

# 1. Check for existing directory
ls -d ../<task-slug> 2>/dev/null

# 2. Check for existing branch
git branch --list <task-slug>

# 3. Check for "ghost" worktrees (metadata exists but directory is gone)
git worktree list | grep "<task-slug>"

Handling Conflicts:

• Directory exists: If ../<task-slug> already exists, ask the user if they want to use it or delete it.
• Branch exists: If the branch exists but no worktree is attached, ask to use the existing branch (git worktree add ../<task-slug> <task-slug>) or delete it.
• Ghost worktree: If git worktree list shows the path but the directory is missing, run git worktree prune to clear the stale metadata. bash scripts/cleanup-worktrees.sh does this plus reports any worktree whose branch is already merged or deleted — advisory only, it prints the git worktree remove/git branch -d commands rather than running them, so review before acting.

# From the main repo root (not another worktree)
git worktree add ../<task-slug> -b <task-slug>
cd ../<task-slug>

If the user prefers a branch without a worktree:

git checkout -b <task-slug>

HARD GATE (e39s02): Acquire story lock in specs/agent-locks.yaml before running tests.

LOCK="specs/agent-locks.yaml"; STORY="<story-id>"
if [ -f "$LOCK" ]; then
  python3 -c "
import yaml,sys,datetime
d=yaml.safe_load(open('$LOCK'))or{'locks':[]}
for l in d['locks']:
  if l['story_id']=='$STORY':print(f'LOCKED by {l[\"locked_by\"]} at {l[\"locked_at\"]}');sys.exit(1)
d['locks'].append({'story_id':'$STORY','locked_by':'agent: build-epic','locked_at':datetime.datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%SZ'),'files_touched':[]})
yaml.dump(d,open('$LOCK','w'),default_flow_style=False)
print(f'LOCK ACQUIRED: $STORY')
"
fi

If locked: abort. If unlocked: entry added, proceed.

Run Preflight (from CLAUDE.md Commands table, or BP_PREFLIGHT from bash scripts/bp-read-agents.sh) and confirm green before writing any code:

# Preflight — project's full local verification stack
# bigpowers example:
npm run compliance && bash scripts/run-verification-gates.sh

# Or project-specific from CLAUDE.md / AGENTS.md

• Preflight passes (all chained gates green)
• No type errors (npm run typecheck or equivalent, if not in Preflight)
• No lint errors (npm run lint or equivalent, if not in Preflight)

If Preflight is red, stop — route to quick-fix or fix-bug. Fix before kickoff continues.

Report: ✓ Preflight green + branch + worktree. Suggest next: develop-tdd or execute-plan.

Gate: READY -> next: develop-tdd Writes: state.yaml handoff.next_skill = develop-tdd