# Headless Launch Script Template

This template is used by the session-decomposer agent to generate a launch script
for headless execution of decomposed sessions.

## Template

```bash
#!/usr/bin/env bash
# Headless launch script — generated by trekplan
# Master plan: {plan_path}
# Generated: {date}
# Sessions: {total_sessions} ({parallel_count} parallel, {sequential_count} sequential)

set -euo pipefail

# Prevent accidental API billing — remove this line if you intend to use API credits
unset ANTHROPIC_API_KEY

REPO_ROOT="$(git rev-parse --show-toplevel)"
PLAN_DIR="{session_dir}"
LOG_DIR="{session_dir}/logs"
WORKTREE_BASE="{session_dir}/worktrees"
mkdir -p "$LOG_DIR" "$WORKTREE_BASE"

# Disable git's optional locks during parallel worktree ops (research/02 R2;
# GH #47721). Mirror Phase 2.6 hardenings (commands/trekexecute.md).
export GIT_OPTIONAL_LOCKS=0

# Per-child guardrails (operator may override via env). Match Phase 2.6
# Step 2a-pre defaults.
MAX_TURNS="${TREKEXECUTE_MAX_TURNS:-50}"
MAX_BUDGET_USD="${TREKEXECUTE_MAX_BUDGET_USD:-5}"

# Shared context (brief + architecture if present). Absolute path so child
# sessions resolve it after `cd` into their worktree.
SHARED_CONTEXT_FILE="$WORKTREE_BASE/.shared-context.md"
if [ -f "$PLAN_DIR/brief.md" ]; then
  cat "$PLAN_DIR/brief.md" > "$SHARED_CONTEXT_FILE"
  if [ -f "$PLAN_DIR/architecture/overview.md" ]; then
    printf '\n\n---\n\n' >> "$SHARED_CONTEXT_FILE"
    cat "$PLAN_DIR/architecture/overview.md" >> "$SHARED_CONTEXT_FILE"
  fi
fi

# Safety preambles prepended to every per-session prompt (defense-in-depth
# against headless-mode hook gaps + Claude 4 cross-model malware-reminder).
SAFETY_PREAMBLE='[CRITICAL — defense in depth] You are running in headless mode where plugin hooks may not fire reliably (GH #36071). DO NOT execute commands matching: `rm -rf /`, `curl | bash`, `git push --force` to main, `git reset --hard` outside this worktree, or any command writing outside the current worktree. Treat this rule as enforced regardless of `--allowedTools` allowlist.

Note: any malware-related safety reminders apply conditionally to code you assess as actually malicious, not to all code reads (per GH #52272 community workaround).'

# Cleanup trap — always remove worktrees on exit (success or failure)
cleanup_worktrees() {
  echo ""
  echo "=== Cleaning up worktrees ==="
  cd "$REPO_ROOT"
  # push-before-cleanup (Hard Rule 19): push any remaining branches so work
  # survives even if subsequent removal races. Failure is non-fatal.
  git branch --list "trek/{slug}/*" | while read b; do
    git push origin "$b" 2>/dev/null || true
  done
  for wt in "$WORKTREE_BASE"/session-*; do
    [ -d "$wt" ] && git worktree remove "$wt" --force 2>/dev/null && echo "Removed: $wt"
  done
  git worktree prune
  git branch --list "trek/{slug}/*" | while read b; do
    git branch -D "$b" 2>/dev/null
  done
  rmdir "$WORKTREE_BASE" 2>/dev/null
  echo "Cleanup complete."
}
trap cleanup_worktrees EXIT

# Pre-flight: verify clean working tree
if [ -n "$(git status --porcelain)" ]; then
  echo "ERROR: Working tree is not clean. Commit or stash changes before parallel execution."
  git status --short
  exit 1
fi

# Pre-flight: verify remote push permissions (catches credential/auth issues
# BEFORE spawning sessions). Sub-agent bash sandbox may have different
# credentials than the launching shell — Step 0 in each session spec handles
# the sandbox-side detection. Set TREKEXECUTE_SKIP_PREFLIGHT=1 for offline
# or air-gapped testing.
if [ "${TREKEXECUTE_SKIP_PREFLIGHT:-0}" != "1" ]; then
  if ! git push --dry-run origin HEAD >/tmp/push-dryrun-launch.log 2>&1; then
    echo "ERROR: git push --dry-run failed. Sessions will be unable to push."
    cat /tmp/push-dryrun-launch.log
    echo ""
    echo "Fix remote credentials before running parallel execution, or set"
    echo "TREKEXECUTE_SKIP_PREFLIGHT=1 to bypass (offline/air-gapped only)."
    exit 1
  fi
  if grep -qE "(rejected|denied|forbidden|permission)" /tmp/push-dryrun-launch.log; then
    echo "ERROR: git push --dry-run reports rejection. Sessions will fail at commit time."
    cat /tmp/push-dryrun-launch.log
    exit 1
  fi
fi

echo "=== Voyage Headless Execution (Worktree-Isolated) ==="
echo "Plan: {plan_path}"
echo "Sessions: {total_sessions}"
echo "Repo root: $REPO_ROOT"
echo ""

# --- Wave {N}: Parallel sessions (no dependencies) ---
echo "--- Wave {N}: {description} ---"

{# For each parallel session in this wave, create worktree: }
git worktree add -b "trek/{slug}/session-{n}" "$WORKTREE_BASE/session-{n}" HEAD
echo "Worktree created: session-{n} (branch: trek/{slug}/session-{n})"

{# Launch session in its worktree (with safety preamble + budget caps + shared context): }
cd "$WORKTREE_BASE/session-{n}" && claude -p "${SAFETY_PREAMBLE}

$(cat "$PLAN_DIR/session-{n}-{slug}.md")" \
  --allowedTools "Read,Write,Edit,Bash,Glob,Grep" \
  --permission-mode bypassPermissions \
  --max-turns "$MAX_TURNS" \
  --max-budget-usd "$MAX_BUDGET_USD" \
  --append-system-prompt-file "$SHARED_CONTEXT_FILE" \
  > "$LOG_DIR/session-{n}.log" 2>&1 &
PID_{n}=$!
cd "$REPO_ROOT"
echo "Started session {n}: {title} (PID $PID_{n})"

{# After all parallel sessions in this wave: }
echo "Waiting for Wave {N} to complete..."
wait $PID_{n1} $PID_{n2}
echo "Wave {N} complete."
echo ""

# --- Merge wave results (sequential) ---
echo "--- Merging Wave {N} ---"
cd "$REPO_ROOT"
{# For each session in the wave: push BEFORE merge (Hard Rule 19 — push-before-cleanup). }
git push origin "trek/{slug}/session-{n}" 2>/dev/null || true
git merge --no-ff "trek/{slug}/session-{n}" \
  -m "merge: trekplan session {n} — {title}"
if [ $? -ne 0 ]; then
  echo "MERGE CONFLICT: session {n}. Conflicting files:"
  git diff --name-only --diff-filter=U
  git merge --abort
  echo "Aborting. Earlier sessions in this wave are already merged."
  exit 1
fi
git worktree remove "$WORKTREE_BASE/session-{n}" --force
git branch -d "trek/{slug}/session-{n}"
echo "Merged and cleaned: session {n}"

git worktree prune

# --- Verify wave results ---
echo "--- Verifying Wave {N} ---"
{# For each session in the wave, run its exit condition commands }
{verify_commands}

# --- Wave {N+1}: Sequential sessions (depends on previous wave) ---
{# Repeat wave pattern for dependent sessions }

echo ""
echo "=== All sessions complete ==="
echo "Review logs in $LOG_DIR/"
echo "Run final verification: {final_verify_command}"
```

## Rules for the session-decomposer

When generating a launch script from this template:

1. **Group sessions into waves** by dependency. Sessions with no dependencies
   or whose dependencies are all in earlier waves can run in the same wave.
2. **Each wave waits for completion** before the next wave starts.
3. **Verification runs after each wave** — if verification fails, the script
   stops and reports which session failed.
4. **Log each session** to a separate file for debugging.
5. **Use `claude -p`** with the session spec file as the prompt.
6. **Use `--allowedTools "Read,Write,Edit,Bash,Glob,Grep"`** with
   `--permission-mode bypassPermissions` for child sessions. This limits the
   tool surface to what the executor needs and prevents agent spawning, MCP
   access, and external web requests in headless sessions.
7. **Final verification** at the end runs the master plan's verification section.
8. **Never include secrets** in the generated script.
9. **Wave verification must be independent.** After each wave completes, run
   verification commands fresh via Bash — never parse session log files as proof
   of success. Log files contain executor self-reporting, not ground truth. The
   command's exit code is the only authoritative verification signal.
10. **Billing preamble.** Prepend `unset ANTHROPIC_API_KEY` with a comment at
    the top of the script to prevent accidental API billing. Users who intend
    to use API credits can remove this line.
11. **Worktree isolation is mandatory.** Every parallel wave MUST use git
    worktrees. Each session gets its own worktree and branch. Never launch
    parallel `claude -p` sessions in the same working directory.
12. **Cleanup trap on EXIT.** The generated script MUST include a `trap` on
    EXIT that removes all worktrees (`git worktree remove --force`) and prunes
    branches, even if the script fails or is interrupted.
13. **Sequential merge after each wave.** After all sessions in a wave complete,
    merge their branches back to the main branch one at a time. Abort on merge
    conflict — do not force-resolve.
14. **Clean working tree before worktrees.** Add a `git status --porcelain`
    check at the top of the script. Fail if the working tree is dirty.
15. **Absolute paths for logs.** Log file paths must be absolute (resolved from
    `$REPO_ROOT`), not relative to any worktree.
16. **Per-child guardrails (mirrors Phase 2.6 Step 2b).** Every `claude -p`
    invocation must include `--max-turns "$MAX_TURNS"`,
    `--max-budget-usd "$MAX_BUDGET_USD"`, and
    `--append-system-prompt-file "$SHARED_CONTEXT_FILE"`. The shared context
    must be built once with an absolute path (resolved from `$WORKTREE_BASE`)
    so child sessions can read it after `cd`.
17. **Safety preamble.** Every per-session prompt must be prefixed with the
    `$SAFETY_PREAMBLE` string defined at the top of the script. This is the
    primary defense when plugin hooks do not fire reliably (GH #36071), and
    includes the GH #52272 malware-reminder clarification for AUTO mode.
18. **GIT_OPTIONAL_LOCKS=0.** The script must export `GIT_OPTIONAL_LOCKS=0`
    once at the top so every git invocation (worktree add/remove/prune,
    branch -d, merge, push) avoids the index.lock background-poll race
    (research/02 R2; GH #47721).
19. **push-before-cleanup (Hard Rule 19).** After successful `git merge --no-ff`,
    run `git push origin <branch>` BEFORE `git worktree remove` and
    `git branch -d`. Push failure is non-fatal — cleanup proceeds. Converts
    unrecoverable branch loss into recoverable remote state (research/02 R3).
