bug: system agent is never created on a fresh install until the backend restarts — /setup creates the admin after the only deploy attempt #3237

Summary

On a fresh install that creates its admin through /setup (every one-click / marketplace path: DigitalOcean, AWS, the hosted script), trinity-system is never deployed until something restarts the backend. The only deploy attempt runs at backend startup, before /setup has created the admin, and fails:

System agent: create_failed - Failed to create system agent: Admin user 'admin' not found

Nothing retries it after /setup succeeds.

Where

• src/backend/main.py → _init_docker_and_system_agent() calls system_agent_service.ensure_deployed() once, at startup.
• src/backend/services/system_agent_service.py → create_system_agent needs the admin user to exist.
• src/backend/routers/setup.py creates the admin and never triggers a deploy.

Reproduction

1. Launch a fresh install (seen on an AWS AMI built from v1.0.0-aws.2, and on v1.0.0-aws.1).
2. Complete /setup.
3. docker ps shows no agent-trinity-system; the backend log has the error above from boot.
4. docker restart trinity-backend → System agent: created - System agent created and started.

On AWS the first IP refresh after a stop/start or an Elastic IP change recreates the backend, which hides the bug on those paths.

Suggested fix

After /setup creates the admin, run system_agent_service.ensure_deployed() (in the background, non-fatal, as at startup). It is idempotent, so a later restart stays a no-op.

Related

• bug: trinity-system agent can never be created on hosts with fewer than 4 CPUs — template cpu:"4" passed to Docker unclamped #2318 (fixed by fix(agents): cap container CPU limit at the Docker host's CPU count (#2318) #3184): the other reason the system agent never started on a 2-vCPU host.
• feat: AWS one-click — Marketplace free AMI (Launch from Website) + CloudFormation Launch Stack link #3004: AWS Marketplace AMI.