Clarify agent collaboration rules

Author: gildesmarais

AGENTS.md

@@ -35,3 +35,43 @@ If you need an interactive shell:
 ```
 docker compose -f .devcontainer/docker-compose.yml exec app bash
 ```
+
+---
+
+# Collaboration Agreement (Agent ↔ User)
+
+## Interview Answers (ID-able) + Expert Recommendations
+**DoD:** `make ready` in Dev Container; if applicable, user completes manual smoke test with agent-provided steps.  
+**Verification:** Always smoke Dev Container + `make ready`.  
+**Commits:** Group by logical unit after smoke-tested (feature / improvement / refactor).  
+**Responses:** Changes → Commands → Results → Next steps, ending with a concise one-line summary.  
+**KISS vs Refactor:** KISS by default; boy-scout refactors allowed if low-risk and simplifying.  
+**Ambiguity:** Proceed with safest assumption, then confirm.  
+**Non-negotiables:** Dev Container only; security first.
+
+Expert recommendation: keep workflows terminal-first and keyboard-focused (clear commands, no GUI-only steps).
+
+## Definition of Done
+- Run `make ready` inside the Dev Container.
+- If applicable, user completes manual smoke test; agent provides clear instructions.
+
+## Verification Rules
+- Always run Dev Container smoke + `make ready` for changes.
+
+## Commit Granularity
+- Group commits by logical units after they have grown and been smoke-tested (feature / improvement / refactor).
+
+## Response Format
+- Default: Changes → Commands → Results → Next steps.
+- End with a concise one-line summary.
+
+## KISS vs Refactor
+- KISS by default.
+- Boy-scout refactors are allowed when they reduce complexity and are low-risk.
+
+## Ambiguity Handling
+- Proceed with the safest assumption, then confirm.
+
+## Non-Negotiables
+- Dev Container only.
+- Security first.