Lab 9 — Background agents and delegation

Capability: Codex can delegate to child agents. A two-agent concurrency cap bounds the example; it is not a claim of deterministic joins, tenant isolation or ACA Sandboxes.

Install Codex CLI; create a private temporary CODEX_HOME, copy this lab’s config.toml.example to $CODEX_HOME/config.toml and fill in the endpoint (ending in /openai/v1) and deployment. Provide AZURE_OPENAI_API_KEY through your resource key from a secret manager. The Microsoft guide says Entra ID is not supported for Codex; never save the key in files. Check codex features list for multi_agent before running. Workspace: start in lab09-background-agents/ and follow the common preflight. Add two independent files:

"name: demo-order`nport: 3000`nqueue: orders-demo" |
  Set-Content (Join-Path $workdir 'order.txt') -Encoding utf8
"name: demo-makeline`nport: 3001`nconsumes: orders-demo" |
  Set-Content (Join-Path $workdir 'makeline.txt') -Encoding utf8
codex exec --skip-git-repo-check -C "$workdir" --sandbox read-only --json `
  "Delegate analysis of order.txt and makeline.txt to separate child agents if supported; await both results and list each service's port and queue with file citations, sorted by service name."

printf 'name: demo-order\nport: 3000\nqueue: orders-demo\n' > "$workdir/order.txt"
printf 'name: demo-makeline\nport: 3001\nconsumes: orders-demo\n' > "$workdir/makeline.txt"

Run codex exec --skip-git-repo-check -C "$workdir" --sandbox read-only --json "Delegate analysis of order.txt and makeline.txt to separate child agents if supported; await both results and list each service's port and queue with file citations, sorted by service name.". Inspect collaboration events to confirm spawning actually happened. Repeat in a new session without delegation; compare wall time, reported tokens and completeness. If the installed Codex version/model/provider does not spawn children, report the feature unavailable rather than calling a single run parallel.

No children should write shared files. This exercise does not reproduce the build-your-own scheduler, deterministic state merge, background response polling or tenant-isolated sandbox lifecycle.

Use a new codex exec call, not resume, for the no-delegation comparison. Follow reset and cleanup afterward.