Headless automation: add retry, verification, and resume to `claude -p`

Problem

claude -p runs a single prompt headlessly but has no built-in loop for iterating until an objective is met. In practice, headless automation needs three things that are currently missing:

1. Verification loop

Run Claude, then run a verification command (e.g. npm test, cargo build). If it fails, feed the error back to Claude and retry. Keep going until verification passes or max iterations hit.

Today you need an external wrapper script for this. Something like:

while true; do
  claude -p "$PROMPT" --resume "$SESSION_ID" --output-format json
  npm test && break  # verify
  PROMPT="Tests failed: $(npm test 2>&1). Fix it."
done

2. Crash recovery / resume

If Claude crashes mid-run (rate limit, OOM, network), the session is lost unless you manually --resume with the session ID. A headless runner should:

• Persist session ID and iteration count to disk
• On restart, detect the previous session and resume automatically
• Classify the failure (transient → retry with backoff, auth → stop, poison context → new session)

3. Exit code contract

claude -p should exit with meaningful codes:

• 0 = task completed successfully
• 1 = task failed (Claude gave up or max iterations)
• 2 = crash/infrastructure failure (retryable)

This would let CI/CD pipelines and cron jobs use Claude reliably.

Proposed UX

# Run until `npm test` passes, max 5 iterations, auto-resume on crash
claude -p "Fix the failing tests" \
  --verify "npm test" \
  --max-iterations 5 \
  --resume-on-crash

Or a config file approach:

# .claude/headless.yaml
prompt: "Fix the failing tests"
verify:
  - name: tests
    command: npm test
  - name: typecheck
    command: npx tsc --noEmit
max_iterations: 5
resume_on_crash: true

Why this matters

Headless Claude is increasingly used for CI, batch processing, and autonomous coding loops. Without built-in retry/verify/resume, every team writes their own bash wrapper — and most get crash recovery wrong.

This is the single biggest gap between "Claude as a tool" and "Claude as a reliable automation primitive."