docs(state): Slice 7 — FUT squad read+write retail-validated on FIFA 17

Record the staged retail A/B: FIFA consumed the Rust squad path end-to-end
(userMassInfo overlay, in-game swap -> squad-replace {"id":0}, formation
f442->f433 persisted to Core, cold relaunch returned the persisted squad),
with Python rollback / Rust re-enable proven by host-log presence. Note the
OPENFUT_DEV_CONTENT_GAMES=fifa17 startup requirement (silent empty /collection
if omitted) as a needed deployment/preflight assertion.

docs/PROJECT_STATE.md

@@ -104,6 +104,26 @@ Last compiled from repository evidence during context initialization.
   (sometimes bulk `count=100`) — Core honours `offset` and terminates; the My Club UI
   nests team under league; the "~1900" club counter is Python `userMassInfo`, not `/club`.
   Remaining is operational only (promote the staged stack to a durable deployment).
+- **Slice 7 (2026-08-12): FUT squad authority (read + write) RUNTIME VALIDATED on retail FIFA 17.**
+  Staged operator-assisted A/B (`.105` retail client → `.120`, source-scoped utas switch
+  `:8099→:8199` into `openfut-utas-host` over a staged `615c5fd` Core seeded by `seed-dev` with the
+  dev 33-card inventory). FIFA itself consumed the Rust squad path end-to-end: FUT boot served
+  `RUST_OVERLAY userMassInfo` (squad overlay) and the squad screen rendered the dev XI; a controlled
+  in-game squad edit issued `PUT …/squad/0` → host `squad-replace` → Core → `{"id":0}`; an in-game
+  formation change f442→f433 persisted to Core (canonical fingerprint changed, `position_index`
+  remapped 0–10); a FULL FIFA relaunch cold-fetched and rendered the persisted f433 squad (no client
+  cache). Reversibility proven on the exact client path by log presence, not response data (both
+  backends coincidentally hold the same dev squad — the Python oracle `fifa17_profile.json` was
+  seeded from the same `squad_put_f442.json` capture): disarmed `.105:8099` reached Python (absent
+  from host log), re-armed reached Rust (`route=club limit=Some(9)` present); the persistent identity
+  store survived the cycle with 0 reallocation. Non-migrated routes (`/ut/auth`, `account/sync`,
+  `accountinfo`, `settings`, `hub`, store txn) correctly Python-fallback. NEW startup requirement:
+  the Core server loads dev card defs only for games in env `OPENFUT_DEV_CONTENT_GAMES` (comma-sep);
+  omitting `fifa17` makes `get_collection` silently drop every owned card (empty `/collection`,
+  "no squad") despite a successful seed — MUST become a deployment/preflight assertion. Preceded the
+  same day by a staged two-process parity gate (real Core+host over HTTP, no FIFA) confirming byte-
+  shape parity of `userMassInfo.squad` vs the captured oracle. Next milestone: real-data Core
+  import / profile strategy → production Rust UTAS. Blaze deferred.
 
 ## Stubbed / planned