chore(coordination+docs): watcher mandat AGENTS.md, recadrage POC CLAUDE.md, dette enrichie, loop script robustifié

AGENTS.md

@@ -10,3 +10,15 @@ Rules:
 - If graphify-out/wiki/index.md exists, use it for broad navigation instead of raw source browsing.
 - Read graphify-out/GRAPH_REPORT.md only for broad architecture review or when query/path/explain do not surface enough context.
 - After modifying code, run `graphify update .` to keep the graph current (AST-only, no API cost).
+
+## coordination watcher
+
+At the beginning of every session, the coordination watcher is mandatory and must be operational for Codex, Claude, and Qwen before coordination work continues.
+
+Session-start checklist:
+- Run `docs/coordination/coordination_loop.sh ensure`.
+- Read every pending message relevant to the current agent.
+- After messages are processed, run `docs/coordination/coordination_loop.sh ack`.
+- If the watcher cannot be started or checked, report that blocker immediately in the handoff/status response.
+
+Every new handoff or restart prompt must include this watcher requirement by default.