fix: fence reconciliation admission race

docs/implementation-plan.v1.md

@@ -1751,6 +1751,12 @@ a lost final `EventAck` followed by server retention. Write this idempotent
 result before dispatch. A client with unresolved essential-store corruption
 cannot complete reconciliation or accept work.
 
+Capture one server receipt-time cutoff immediately before registering the live
+session, and use that identical cutoff when building `ReconcileRequest` and
+applying its `ReconcileSnapshot`. A command admitted after that cutoff is new
+work: it must remain queued for post-reconciliation dispatch, never be treated
+as absent client evidence merely because its admission raced the handshake.
+
 Implement reconciliation as this explicit matrix:
 
 | Server state | Client evidence | Durable result |