Say in goal 7 that the scope floor covers the seam too, and decline merge-state persistence

AGENTS.md

@@ -34,8 +34,10 @@ one wins. They do not override the hard rules below.
    promise this library can verify. The low-level surface is a passthrough: policy binds what the
    library composes, never what the caller wrote.
 7. **Nothing that needs state wider than one session.** No throughput throttling, no persistence
-   across a restart, no coordination between processes. This is the scope floor, and it is why an
-   otherwise reasonable feature is declined without a fresh argument each time.
+   across a restart, no coordination between processes — and no seam handing the application state to
+   persist for one of those either, which commits to the same scope through the back door and
+   publishes an internal shape to do it. This is the scope floor, and it is why an otherwise
+   reasonable feature is declined without a fresh argument each time.
 8. **It builds, tests and runs the same everywhere.** Container-only toolchain, no runtime
    dependencies, the Node 18 floor verified in CI rather than asserted, every README example executed
    by the suite.

todo.md

@@ -118,10 +118,6 @@ session message is a change to every call site.
 
 ## Worth doing, not blocking
 
-- [ ] **Merge state does not survive a process restart.** A drop no longer discards it, but a restart
-      loses every incomplete group, and a peer has no reason to resend a receipt it already had
-      answered. Surviving one means exposing the merge state for the application to persist and hand
-      back, which is a public-surface decision.
 - [ ] **Group the session's collaborators under `src/session/`.** `session.ts` imports
       `dlr-merger`, `incoming-requests`, `link-timers`, `outgoing-requests`, `pdu-transport`,
       `reconnect-loop` and `send-sms`, and nothing else does, so the directory would make that
@@ -168,6 +164,13 @@ session message is a change to every call site.
 
 ## Declined
 
+- **Merge state surviving a process restart.** Declined by AGENTS.md goal 7, maintainer's call,
+  2026-09-02. A restart loses every incomplete receipt group and a peer has no reason to resend one it
+  already had answered, so the loss is real — but surviving it means handing the application the merge
+  state to persist, which the scope floor covers as squarely as holding the state here would, and
+  which publishes the shape of `DlrMerger`'s groups against goal 6. Nothing is foreclosed: the seam
+  can still be added after 1.0.0 as a minor.
+
 - **Throughput throttling — a TPS cap, and backing off on `ESME_RTHROTTLED`.** Declined by AGENTS.md
   goal 7: an operator's rate limit is scoped to the account, while the widest thing this library owns
   is a session, so a bucket here cannot see a second process binding the same account and is wrong in