docs(runtime): record game runtime root gate

docs/plans/2026-07-26-modern-runtime-slice-j7.md

@@ -82,6 +82,8 @@ introduced.
 
 ### J7.1 — Runtime root, identity, events, and terminal ledger
 
+**Complete 2026-07-26 at `96ddd165`.**
+
 - Add `GameRuntime`, typed construction dependencies, local-player identity,
   construction fault points, ownership snapshot, and exact teardown stages.
 - Move the normalized view/checkpoint implementation into the root.
@@ -93,6 +95,15 @@ introduced.
 Gate: focused Runtime tests pass and dependency/source guards find no App or
 backend reference.
 
+Result: one `GameRuntime` now constructs and owns session, local identity,
+entity/object/physics, gameplay, movement, environment, transit, clock, and
+lazy normalized events. Typed host leases prevent early retirement.
+Construction rollback drains acquired children in reverse; terminal disposal
+uses an exact stage cursor and ownership ledger. The focused 18-test root
+matrix, all 383 Runtime tests, Release build, and complete 8,660-test /
+5-skip solution pass. Production still uses the existing graphical
+construction path until J7.2 performs the isolated cutover.
+
 ### J7.2 — production composition cutover
 
 - Construct one root in `GameWindow`.
@@ -161,5 +172,11 @@ Release gates. Record its full production SHA and exact `git revert <sha>` here
 before beginning the next sub-slice. Documentation-only commits are not
 behavior rollback points.
 
+J7.1 exact rollback:
+
+```text
+git revert 96ddd16539e670a5ce9b1f86677530e3fbc3f635
+```
+
 No compatibility owner, service locator, asynchronous command queue, timeout,
 forced-ready path, or alternate headless behavior is permitted.