[AI] Reduce webassembly heap by freeing all prepared statements (#9131)

* [AI] Free sql.js statements prepared by runQuery

In the browser, runQuery prepared a new statement for every string query
but only freed it for queries that fetch rows. sql.js keeps unfreed
statements in the WASM heap until the database closes, so a cold load of
a large budget (~500k spreadsheet cache writes) grew the heap by hundreds
of MB. Free (or reset) the statement in all paths, including on error.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_016C82Fnx6cnESa3HUTuM9SE

* [AI] Add release note

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_016C82Fnx6cnESa3HUTuM9SE

* bump

---------

Co-authored-by: Claude Opus 5.5 <[email protected]>
Co-authored-by: Michael Clark <[email protected]>

packages/loot-core/src/platform/server/sqlite/index.test.ts

@@ -193,4 +193,21 @@ describe('Web sqlite', () => {
     // @ts-expect-error Property 'id' does not exist on type 'unknown'
     expect(rows[0].id).toBe('id1');
   });
+
+  it('should free statements it prepares', async () => {
+    const db = await openDatabase();
+    execQuery(db, initSQL);
+    const prepare = vi.spyOn(db, 'prepare');
+
+    runQuery(db, "INSERT INTO numbers (id, number) VALUES ('id1', 4)");
+    runQuery(db, 'SELECT * FROM numbers', [], true);
+    expect(() =>
+      runQuery(db, "INSERT INTO numbers (id, number) VALUES ('id1', 5)"),
+    ).toThrow(/constraint failed/);
+
+    expect(prepare).toHaveBeenCalledTimes(3);
+    for (const { value: statement } of prepare.mock.results) {
+      expect(() => statement.run()).toThrow(/Statement closed/);
+    }
+  });
 });

packages/loot-core/src/platform/server/sqlite/index.ts

@@ -109,28 +109,31 @@ export function runQuery<T>(
 
   const stmt = typeof sql === 'string' ? db.prepare(sql) : sql;
 
-  if (fetchAll) {
-    try {
-      stmt.bind(params);
-      const rows = [];
+  try {
+    if (fetchAll) {
+      try {
+        stmt.bind(params);
+        const rows = [];
 
-      while (stmt.step()) {
-        rows.push(stmt.getAsObject());
+        while (stmt.step()) {
+          rows.push(stmt.getAsObject());
+        }
+        return rows;
+      } catch (e) {
+        logger.log(sql);
+        throw e;
       }
-
-      if (typeof sql === 'string') {
-        stmt.free();
-      } else {
-        stmt.reset();
-      }
-      return rows;
-    } catch (e) {
-      logger.log(sql);
-      throw e;
     }
-  } else {
+
     stmt.run(params);
     return { changes: db.getRowsModified() };
+  } finally {
+    // sql.js keeps statements alive in the WASM heap until they are freed.
+    if (typeof sql === 'string') {
+      stmt.free();
+    } else {
+      stmt.reset();
+    }
   }
 }
 

upcoming-release-notes/fix-browser-memory-large-budgets.md

@@ -0,0 +1,6 @@
+---
+category: Bugfix
+authors: [mbrevda]
+---
+
+Fix high memory use in the browser after opening a large budget