One applier for a WAL connection's policy (foreign_keys + synchronous)

src/agent_comms/coordination/database.py

@@ -137,12 +137,11 @@ def configure_connection(cls, connection: sqlite3.Connection) -> None:
         for row_type in CoordinatorTable.declarations():
             row_type.configure_connection(connection)
         connection.row_factory = sqlite3.Row
-        connection.execute("PRAGMA foreign_keys = ON")
-        # WAL is set once, on the private stage before the file is published (or by the
-        # coordinator_wal carry with every owner stopped), and persists in the file header, so
-        # no opener switches the mode and fresh openers cannot race over it. The durability of
-        # a commit is the one StoreWriter policy every WAL writer shares, not a literal here.
-        connection.execute(f"PRAGMA synchronous = {cls.synchronous}")
+        # Referential integrity and commit durability are the one WAL-writer policy on
+        # StoreWriter, applied here, not restated. WAL itself is set once on the private stage
+        # before the file is published (or by the coordinator_wal carry with every owner
+        # stopped) and persists in the file header, so no opener switches the mode.
+        cls.apply_connection_policy(connection)
 
     def _prepare_private_file(self) -> None:
         self.path.parent.mkdir(parents=True, exist_ok=True)

src/agent_comms/storage/typed_table.py

@@ -3282,6 +3282,14 @@ class StoreWriter(PublishedSQLiteFile):
     # store that must survive power loss raises its own bar (goal stores declare EXTRA).
     synchronous: ClassVar[str] = "NORMAL"
 
+    @classmethod
+    def apply_connection_policy(cls, connection: sqlite3.Connection) -> None:
+        """The per-connection policy every WAL writer here applies: referential integrity on,
+        and the one synchronous durability this family shares. A store that opens a WAL
+        connection applies this and nothing of its own, so no two openers can disagree."""
+        connection.execute("PRAGMA foreign_keys = ON")
+        connection.execute(f"PRAGMA synchronous = {cls.synchronous}")
+
     @property
     @abstractmethod
     def store(self) -> WrittenFile:
@@ -3576,8 +3584,7 @@ def _configured_writer(
         connection = self.writer(
             path, isolation_level=None, check_same_thread=check_same_thread)
         try:
-            connection.execute(f"PRAGMA synchronous={self.synchronous}")
-            connection.execute("PRAGMA foreign_keys=ON")
+            self.apply_connection_policy(connection)
             if not SQLiteJournalMode.write_ahead(connection.execute("PRAGMA journal_mode=WAL")):
                 raise RelationViolationError(f"{self.filename} requires WAL")
             yield connection