STATE-WP-0098: inbox change-feed contract accepted (D1-D4); add T05 implementation

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 356991@bnt-lap001
Assistant-Session: 5d99ea69-ed55-4a1e-8d97-f4f312db247f

docs/inbox-change-feed-contract.md

@@ -1,6 +1,7 @@
-# State Hub inbox change-feed contract (draft)
+# State Hub inbox change-feed contract
 
-Status: **draft for review**. Not implemented. Deliverable of `STATE-WP-0098-T03`.
+Status: **accepted** (founder, 2026-10-13: D1-D4 as recommended). Not yet
+implemented; implementation is `STATE-WP-0098-T05`. Deliverable of `STATE-WP-0098-T03`.
 It is the State Hub input for `HUB-WP-0011-T01` (the first row of its
 "Dependency review — 2026-10-04" table). Date: 2026-10-13.
 
@@ -206,10 +207,11 @@ whether that table is populated in the State Hub DB. Aliases are not in v1.
   `(message_id, revision, deleted_at)`. It must not keep the body.
 - **Hub-core never emits its own tombstones.**
 
-### Open founder decisions
+### Founder decisions (resolved 2026-10-13)
 
-These are not settled by T08/T09. They must be answered before hub-core
-implements against this contract.
+The T08/T09 record did not settle these. The founder accepted all four
+recommendations on 2026-10-13: 90-day tombstones (D1), no purge (D2),
+delivery-stamp loss accepted (D3), migration approved (D4).
 
 - **D1 — Tombstone retention horizon.** *Recommend:* keep tombstones for 90
   days, and at least twice the maximum consumer lag. A cursor older than the