docs(runtime): close communication ownership

Record J4.1's single Runtime communication/social graph, failure-safe ordered chat stream, complete Release evidence, exact-binary lifecycle/reconnect acceptance, rollback, and the J4.2 inventory transaction boundary. Synchronize architecture, roadmap, milestones, agent guidance, and durable memory.

Co-authored-by: Codex <codex@openai.com>

docs/research/2026-07-26-slice-j4-1-communication-state.md

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+# Modern runtime J4.1 — communication/social ownership
+
+**Status:** COMPLETE
+**Production commit:** `c9d25ade50c0a5c4f7db5b6cca680e01e35cc18e`
+**Parent plan:** `../plans/2026-07-26-modern-runtime-slice-j4.md`
+
+## Result
+
+`RuntimeCommunicationState` is the single presentation-independent owner for
+the live chat transcript, reply/retell command targets, negotiated Turbine
+rooms and context cookies, friends, and squelch database.
+
+The live-session router, client commands, retained retail UI, developer tools,
+current-runtime/plugin boundary, and future no-window hosts borrow those exact
+instances. `GameWindow` retains read-only compatibility aliases only; it no
+longer constructs a communication or social state object.
+
+Reply/retell tracking moved out of `ChatVM`. A ViewModel may construct a
+private tracker for isolated UI tests, while production ViewModels borrow the
+Runtime tracker. Disposing one borrowed ViewModel cannot detach or reset the
+shared command state.
+
+The Runtime chat stream subscribes once to the canonical `ChatLog`, assigns a
+monotonic commit sequence, and dispatches synchronously. Its retained in-call
+drain prevents a re-entrant callback from delivering a later entry to one
+observer before an earlier entry. Observer exceptions are recorded and do not
+starve later observers or roll back the committed transcript. No async queue,
+polling mirror, or extra frame was introduced.
+
+Session reset preserves visible transcript history while independently
+clearing reply/retell targets, local speaker identity and dedupe state,
+negotiated rooms/cookie sequence, friends, and squelch state in the existing
+retail-derived reset order.
+
+## Automated evidence
+
+- Runtime suite: 152 passed.
+- App suite: 3,765 passed / 3 established skips.
+- UI abstractions: 545 passed.
+- Core: 3,294 passed / 2 established skips.
+- Core.Net: 600 passed.
+- Complete Release solution: 8,494 passed / 5 established skips.
+- Release build: pass, zero errors. A clean rebuild reports 17 pre-existing
+  Core-test warnings; the J4.1 diff introduces none.
+- `git diff --check`: pass.
+
+The focused matrix covers incoming/outgoing tells, shared ViewModel borrowing,
+reset without transcript loss, duplicate subscription rejection, callback
+re-entrancy, observer failure isolation, direct/idempotent disposal, two
+independent Runtime instances, current-runtime event forwarding, UI
+composition, and shutdown ordering.
+
+## Exact-binary connected evidence
+
+`logs/connected-world-gate-20260726-075109/report.json` passed on exact source
+and embedded binary commit
+`c9d25ade50c0a5c4f7db5b6cca680e01e35cc18e`:
+
+- six capped checkpoints through login, outdoor/dungeon/facility travel and
+  revisit plus one fresh-process uncapped reconnect checkpoint;
+- 245.687-second capped route and 61.638-second reconnect route;
+- both sessions exited gracefully with code zero;
+- zero failures, render-shadow mismatches, pending render deltas, or stranded
+  owner work.
+
+Its only warning is the established set of 25 expected world-edge landblock
+misses.
+
+## Retail and divergence audit
+
+J4.1 changes ownership, observation, and teardown only. Existing retail-derived
+chat parsing, formatting, channel cookies, friend updates, squelch rules, and
+session-reset semantics are unchanged. No divergence row was added or retired.
+
+## Rollback
+
+```text
+git revert c9d25ade50c0a5c4f7db5b6cca680e01e35cc18e
+```
+
+Do not revert J3 to mask a later gameplay-state ownership failure.
+
+## Next boundary
+
+J4.2 moves the external-container, item-mana, shortcut/component, shared busy,
+and one-inventory-request-at-a-time owners into Runtime while borrowing J3's
+exact `ClientObjectTable`. Retained drag/drop projections, icons, cursors,
+selection, and panel state stay in App/UI.