Implement agent loop contract in repo #22

Part of #10

Question

Nothing to decide — execute the contract resolved in What is the agent loop contract? so the repo matches the decision and Corey learns the mechanics by doing.

Goal

Implement and verify the agent-loop contract in the repository, including one tiny docs-only smoke test.

Allowed scope

• AGENTS.md
• docs/agents/triage-labels.md
• docs/adr/agent-loop-contract.md
• Relevant issue and pull-request templates
• One tiny docs-only smoke-test change
• The existing checklist items in this issue

Do not change Plan Gate or .github/scripts unless a checklist item explicitly requires it.

Success criteria

• The agent-loop contract is documented in the repository.
• The required intake and pull-request wording is present.
• The smoke test completes this sequence:
  label → claim → branch → docs-only change → PR with Fixes #n → CODEOWNERS review → human merge
• The smoke-test pull request passes Plan Gate.

Checklist

• Add in-progress to triage vocabulary docs (docs/agents/triage-labels.md, AGENTS.md)
• Ensure GitHub label in-progress exists
• Publish the agent loop contract as durable repo docs (prefer ADR under docs/adr/ + short pointer from AGENTS.md)
• Update issue intake template(s) so Goal / Allowed scope / Success criteria are explicit for ready-for-agent
• Align PR template wording with required vs optional fields from the contract
• Smoke the loop once on a tiny docs-only issue: label → claim → branch chore/#n-… → PR with Fixes #n → CODEOWNERS merge

Learning note

This ticket is intentional hands-on practice for the cert control plane — implement and verify, do not only document.