ReddRadar
Agent skill
use-sub-agent
Use when work should be delegated to one or more headless Codex subagents in the same machine session, especially for parallelizable tasks and when reliable launch, timeout, and log-handling behavior is required.
Install this agent skill to your Project
npx add-skill https://github.com/escarti/agentDevPrompts/tree/main/skills/use-sub-agent
SKILL.md
use-sub-agent
YOU ARE READING THIS SKILL RIGHT NOW
STOP. Before doing ANYTHING else:
- ☐ Create TodoWrite checklist (see below)
- ☐ Mark Step 1 as
in_progress - ☐ Decide single vs parallel subagent plan
If you launched any subagent before creating TodoWrite, you FAILED.
MANDATORY FIRST ACTION: Create TodoWrite
TodoWrite({
todos: [
{content: "Step 1: Identify delegation scope and choose single or parallel subagents", status: "in_progress", activeForm: "Planning delegation"},
{content: "Step 2: Draft subagent prompts with safe shell escaping", status: "pending", activeForm: "Drafting prompts"},
{content: "Step 3: Launch each subagent with codex --yolo exec and 30-minute timeout wrapper", status: "pending", activeForm: "Launching subagents"},
{content: "Step 4: Wait for completion and capture per-subagent exit status", status: "pending", activeForm: "Collecting statuses"},
{content: "Step 5: Inspect each subagent log before declaring success", status: "pending", activeForm: "Reviewing logs"},
{content: "Step 6: Merge successful outputs and rerun failed/incomplete tasks", status: "pending", activeForm: "Merging outputs"},
{content: "Step 7: Report final synthesized result with completion evidence", status: "pending", activeForm: "Reporting result"}
]
})
After each step: mark completed and move in_progress to the next step.
Overview
Delegate independent work to headless Codex subprocesses with predictable launch, timeout, and result collection.
Rules
- Launch each subagent with
codex --yolo exec "...". - Escape shell-sensitive prompt content. Never pass unescaped backticks or
$(). - When running subagents from a shell tool call, set wrapper timeout to 30 minutes (
timeout_ms: 1800000) per run. - For parallel runs, use background jobs and
wait, then inspect each log before declaring success. - Assume subagents inherit CLI defaults (approval, sandbox, model behavior). Keep prompts focused and lightweight.
Single Subagent Pattern
codex --yolo exec "Summarize the diff in src/api/auth.ts and list risks."
Parallel Subagent Pattern
mkdir -p .codex-subagents
codex --yolo exec "Task A prompt..." > .codex-subagents/a.log 2>&1 &
pid_a=$!
codex --yolo exec "Task B prompt..." > .codex-subagents/b.log 2>&1 &
pid_b=$!
wait $pid_a; status_a=$?
wait $pid_b; status_b=$?
echo "A=$status_a B=$status_b"
Result Validation
- Treat wrapper timeout (
124) as inconclusive until logs are reviewed. - Read each log and confirm the subagent reached a final answer.
- Merge outputs only from completed runs. Rerun incomplete runs with narrower prompts.
Common Mistakes
| Mistake | Fix |
|---|---|
| Using plain shell commands and calling them subagents | Use codex --yolo exec for each subagent |
| Missing timeout override | Set timeout_ms: 1800000 for shell tool calls that run subagents |
| Trusting wrapper exit code alone | Always inspect each subagent log |
| Overloading prompts with too much context | Split work and keep each prompt narrow |
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