obra/external-subagents

Codex Subagents

Overview

codex-subagent offloads work to background threads so your main context stays lean. Threads run detached by default; use wait/peek to check results.

Critical rules:

1. You cannot send to a running thread. Always wait before sending follow-ups.
2. Use --permissions read-only or --permissions workspace-write (not workspace-read)

For detailed workflow documentation, see reference/workflow.md.

When to Use

Situation	Why subagents help
Parallel research tasks	Multiple threads run simultaneously
Context would bloat	Research stays in separate thread
Long-running work	Detached execution, check later

Don't use for: Quick inline questions, tightly-coupled work needing your current state.

Core Workflow

1. start with --prompt    (inline text or stdin)
2. wait/peek → check result
3. send → resume with follow-up (ONLY after thread stops)
4. archive/clean → lifecycle management

The Running Thread Rule

You CANNOT send to a running thread. This is the #1 mistake.

# WRONG - thread might still be running
echo "followup" | codex-subagent send thread-abc --prompt -

# RIGHT - wait first, then send
codex-subagent wait --threads thread-abc
echo "followup" | codex-subagent send thread-abc --prompt -

Resumable statuses: completed, failed, stopped, waiting

Quick Reference

Command	Purpose	Key flags
start	Launch new thread	--role, --permissions, --prompt, --label, -w
send	Resume stopped thread	<thread-id>, --prompt, -w
peek	Read newest unseen message	<thread-id>, --save-response
log	Full history	<thread-id>, --tail, --json
status	Thread summary	<thread-id>
wait	Block until threads stop	--threads, --labels, --all, --follow-last
list	Show threads	--status, --label, --role
archive	Move completed to archive	--completed, --yes, --dry-run
clean	Delete old archives	--older-than-days, --yes

Prompt input: --prompt "text" for simple prompts, --prompt - reads from stdin (for multi-line), -f/--prompt-file for files

Positional thread IDs: peek abc123 works like peek -t abc123

Common Patterns

Simple inline prompt

codex-subagent start --role researcher --permissions read-only \
  --label "quick-task" --prompt "List all exported functions in src/lib/"

Multi-line prompt (heredoc)

cat <<'EOF' | codex-subagent start --role researcher --permissions read-only --label "auth-research" --prompt -
Research authentication patterns in this codebase:
1. Find all auth-related files
2. Document the auth flow
3. Note any security concerns
EOF

Parallel research

# Launch multiple researchers
cat <<'EOF' | codex-subagent start --role researcher --permissions read-only --label "API: Stripe" --prompt -
Research Stripe API authentication methods and best practices
EOF

cat <<'EOF' | codex-subagent start --role researcher --permissions read-only --label "API: Twilio" --prompt -
Research Twilio API authentication methods and best practices
EOF

# Wait for all, see results
codex-subagent wait --labels "API:" --follow-last

Blocking task

# -w blocks until complete (may take minutes)
cat <<'EOF' | codex-subagent start --role researcher --permissions read-only --prompt - -w --save-response result.txt
Analyze error handling patterns in src/
EOF
cat result.txt

Warning: -w blocks for as long as the agent runs. For long tasks, prefer detached mode with wait --follow-last.

Cleanup old work

# Two-phase: archive completed, then clean old archives
codex-subagent archive --completed --yes
codex-subagent clean --older-than-days 30 --yes

Troubleshooting

Problem	Cause	Fix
"profile does not exist"	Wrong permissions	Use read-only or workspace-write (not workspace-read)
"not resumable" error	Thread still running	wait first, then send
"different controller"	Wrong session	Use --controller-id or check list
Thread disappeared	Was archived	Check archive dir or re-run task

Checklist

• start has --role, --permissions, --prompt, and --label
• Permissions are read-only or workspace-write
• wait before send (never send to running thread)
• Results captured with --save-response or peek