Add Duo Workflow agent configuration and instructions
Issue: Runner Core AI Workflow Automations (gitlab-org#21329) • Ashvin Sharma
What does this MR do?
Add Duo Workflow agent configuration and instructions
AGENTS.md provides context and guardrails for AI agents .gitlab/duo/agent-config.yml configures the CI environment:
- Cache key is go.sum; paths cover Node.js, Go modules, npm globals, make tools (.tmp/), and development_setup fixtures (tmp/)
Why was this MR needed?
This MR was needed to make duo understand how contribution to runner code is made.