fix(thread): make wait-state side effects atomic

tests/unit/database-transaction.test.ts

@@ -0,0 +1,62 @@
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { mkdtemp, rm } from "node:fs/promises";
+import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+
+beforeAll(() => {
+  process.env.AGENTCOMPANY_ALLOW_INSECURE_VAULT = "true";
+});
+
+vi.mock("electron", () => ({
+  safeStorage: {
+    isEncryptionAvailable: () => false,
+    getSelectedStorageBackend: () => "basic_text",
+    encryptString: (value: string) => Buffer.from(value, "utf8"),
+    decryptString: (value: Buffer) => value.toString("utf8"),
+  },
+}));
+
+import { AppDatabase } from "../../src/main/database";
+
+describe("AppDatabase transactions", () => {
+  let tempDir: string;
+  let db: AppDatabase;
+
+  beforeEach(async () => {
+    tempDir = await mkdtemp(join(tmpdir(), "agentcompany-db-tx-"));
+    db = new AppDatabase(tempDir);
+    db.init();
+  });
+
+  afterEach(async () => {
+    db.close();
+    await rm(tempDir, { recursive: true, force: true });
+  });
+
+  it("rolls back nested transactions to their savepoint", () => {
+    const outerCompanyId = db.withTransaction(() => {
+      const companyId = db.core.company.saveCompany({
+        name: "Nested Transaction Co",
+        description: "Outer transaction should survive inner rollback.",
+        status: "active",
+      });
+
+      expect(() => {
+        db.withTransaction(() => {
+          db.core.company.saveCompany({
+            name: "Nested Transaction Rolled Back",
+            description: "Inner transaction should roll back.",
+            status: "active",
+          });
+          throw new Error("inner write failed");
+        });
+      }).toThrow("inner write failed");
+
+      return companyId;
+    });
+
+    const companies = db.queryAll<{ id: string; name: string }>("select id, name from companies order by created_at asc");
+    expect(companies.map((company) => company.id)).toContain(outerCompanyId);
+    expect(companies.some((company) => company.name === "Nested Transaction Rolled Back")).toBe(false);
+  });
+});