Wave-3 review gate: contract conformance clean; two findings fixed inline — substrate boundary move (open_writer_connection → seam.rs), writer-slot release on with_writer/begin/commit error arms + regression tests (task review-wave-3)

alkstore-sqlite/src/tx.rs

@@ -70,9 +70,13 @@ impl SqliteTxHandle {
                         "the store is closed: writer slot unavailable",
                     ))
                 })?;
-                conn.execute_batch("BEGIN IMMEDIATE")
-                    .map_err(sqlite_error)
-                    .map(|_| conn)
+                match conn.execute_batch("BEGIN IMMEDIATE").map_err(sqlite_error) {
+                    Ok(()) => Ok(conn),
+                    Err(e) => {
+                        writer2.release(conn);
+                        Err(e)
+                    }
+                }
             })
             .await?;
             Ok(Box::new(SqliteTxHandle {
@@ -387,12 +391,23 @@ impl TxHandle for SqliteTxHandle {
             return Box::pin(async { Err(Error::Closed) });
         };
         let writer = self.writer.clone();
+        let writer_reopen = self.reopen.clone();
         Box::pin(async move {
-            blocking(move || {
-                conn.execute_batch("COMMIT").map_err(sqlite_error)?;
-                writer.release(conn);
-                Ok(())
-            })
+            blocking(
+                move || match conn.execute_batch("COMMIT").map_err(sqlite_error) {
+                    Ok(()) => {
+                        writer.release(conn);
+                        Ok(())
+                    }
+                    Err(e) => {
+                        drop(conn);
+                        if let Ok(fresh) = (writer_reopen)() {
+                            writer.release(fresh);
+                        }
+                        Err(e)
+                    }
+                },
+            )
             .await
         })
     }