Roadmap: tick what M5 already delivered

Only the soak harness was still open here: `backend/scripts/soak.py` and
`make soak` exist with all four scenarios, so the Phase 0 item is done —
with the two caveats from NOTEPAD on the line, since the redis scenario
stops a shared container and the engine kill barely stresses redelivery.
The other M5 items (brain graph, modules, out-of-process nodes, engine
history and the health screens) were already ticked and match the code.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XC2jX6Hdj7pxGGKzBTrbqB

ROADMAP.md

@@ -23,9 +23,13 @@ existing flow engine reachable and persistent precedes new feature breadth.
 - [x] Design token contract: root `DESIGN-GUIDELINES.md`, per-repo `DESIGN.md`,
       byte-identical token blocks verified by `make design-check`
 - [ ] CI on Codeberg (Forgejo Actions): pre-commit, backend tests, Playwright, compose smoke
-- [ ] Soak and chaos harness: sustained load with the state backend, the broker and
-      the engine itself taken away underneath it. The reliability layers were verified
-      by hand against a live instance; keeping them verified needs a harness
+- [x] Soak and chaos harness: sustained load with the state backend, the broker and
+      the engine itself taken away underneath it. `backend/scripts/soak.py` behind
+      `make soak`, driving the durable webhook path through load, redis, engine and
+      broker scenarios, with every docker verb checked against an allow-list of this
+      stack's own containers. Two caveats: the redis scenario stops the container the
+      whole stack shares, and a cascade finishes fast enough that the engine kill
+      proves redelivery without stressing it
 
 ## Phase 1 — Backend: management