Await in-flight batch in IndexedDbFileSystem.flush()

sqlite3/CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 3.6.0 (unreleased)
 
+- Fix `IndexedDbFileSystem.flush()` completing before a write batch already in progress was persisted.
 - Hooks: Support relative paths in `additional_includes` and `additional_lib_directories`.
 - Hooks: Support multiple source files to compile with `source: source`.
 - Hooks: `source` and `name` accept a map with per-OS entries and a `default` (e.g. `source: {android: system, default: sqlite3}`). Names containing a path (like `foo.framework/foo`) are passed to the loader as-is with `source: system`.

sqlite3/lib/src/wasm/vfs/indexed_db.dart

@@ -607,7 +607,16 @@ final class IndexedDbFileSystem extends BaseVirtualFileSystem {
   /// Operations started after this [flush] call will not be awaited by the
   /// returned future.
   Future<void> flush() {
-    return _startWorkingIfNeeded(isImplicit: false);
+    if (!_isWorking) {
+      return _startWorkingIfNeeded(isImplicit: false);
+    }
+
+    // A batch is already being written, so `_startWorkingIfNeeded` would take
+    // no branch and complete immediately — before that batch, or anything
+    // queued behind it, reaches IndexedDB. Queue a no-op item instead: it lands
+    // at the tail of `_pendingWork` and completes only once the work ahead of
+    // it has been written, which is the guarantee documented above.
+    return _submitWorkFunction((_) async {}, 'flush');
   }
 
   @override