S16 - some transactional hardening

specs/S16-validation.md

@@ -154,3 +154,27 @@ Retained review signals in changed code:
 One active backend remains the supported deployment model. Global execution
 capacity, distributed workers, database backup/restore and recovery after database
 volume loss remain outside S16. S17 owns backup/restore.
+
+## Review follow-up: database recovery during calculation
+
+Terminal scheduling outcomes whose transaction fails remain pending in their worker.
+The worker retries storage once per second without holding the school monitor between
+attempts, retaining its run guard until the terminal status commits. Publication still
+happens only after commit. Shutdown interrupts the wait; startup recovery remains
+responsible for persisted Running statuses after a process restart. If the show was
+removed during the outage, the pending outcome is discarded rather than recreating
+its status. The finish method's cognitive complexity 12 and cyclomatic complexity 8 distinguish
+retryable storage failures, removed shows and shutdown; these lifecycle decisions
+stay in the run owner. SchedulingRuns fan-out is now 34 and its test fixture fan-out
+35: the added storage exception, interruption handling and outage fixture belong to
+this existing persistence lifecycle boundary.
+
+The regression test simulates unavailable storage during result persistence, verifies
+that no terminal status is published prematurely and duplicate starts remain rejected,
+then restores storage without restarting the backend and checks the stable run ID,
+persisted failure status and released guard. Public transaction/callback documentation
+now specifies transaction ownership, callback timing and exception behavior.
+
+Follow-up verification: clean Maven verify against PostgreSQL passes all 73 backend
+tests and 19 standards-checker tests. Standards and the coverage gate pass;
+backend line coverage is 1769/1841 (96.09%).

specs/implemented/S16_store-state-in-persistent-storage

@@ -1,6 +1,6 @@
 # S16 — Store state in persistent storage
 
-Status: IN_REVIEW
+Status: IMPLEMENTED
 
 Agreed after the grill-me interview; shared understanding confirmed.