fix(keys): add DB fallback to updateEmailByCustomer, updateKeyEmail, and recover route (BUG-108, BUG-109, BUG-110)

- updateEmailByCustomer: DB fallback when stripe_customer_id not in cache
- updateKeyEmail: DB fallback when key not in cache
- POST /v1/recover: DB fallback when email not in cache (was only on verify)
- 6 TDD tests added (keys-email-update.test.ts, recover-initial-db-fallback.test.ts)
- 547 tests total, all passing

src/__tests__/keys-email-update.test.ts

@@ -0,0 +1,109 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+
+// Override the global setup.ts mock for keys — we need the REAL implementation
+vi.unmock("../services/keys.js");
+
+vi.mock("../services/db.js", () => ({
+  default: { query: vi.fn(), connect: vi.fn(), on: vi.fn(), end: vi.fn() },
+  pool: { query: vi.fn(), connect: vi.fn(), on: vi.fn(), end: vi.fn() },
+  queryWithRetry: vi.fn().mockResolvedValue({ rows: [], rowCount: 0 }),
+  connectWithRetry: vi.fn().mockResolvedValue(undefined),
+  initDatabase: vi.fn().mockResolvedValue(undefined),
+  cleanupStaleData: vi.fn(),
+  isTransientError: vi.fn(),
+}));
+
+vi.mock("../services/logger.js", () => ({
+  default: { info: vi.fn(), error: vi.fn(), warn: vi.fn(), debug: vi.fn() },
+}));
+
+import { queryWithRetry } from "../services/db.js";
+import { updateEmailByCustomer, updateKeyEmail } from "../services/keys.js";
+
+const mockQuery = vi.mocked(queryWithRetry);
+
+describe("updateEmailByCustomer DB fallback (BUG-108)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("returns true and updates DB when key is NOT in cache but IS in DB", async () => {
+    mockQuery
+      .mockResolvedValueOnce({
+        rows: [{
+          key: "df_pro_abc123",
+          tier: "pro",
+          email: "old@example.com",
+          created_at: "2026-01-01T00:00:00.000Z",
+          stripe_customer_id: "cus_456",
+        }],
+        rowCount: 1,
+      } as any)
+      .mockResolvedValueOnce({ rows: [], rowCount: 1 } as any); // UPDATE
+
+    const result = await updateEmailByCustomer("cus_456", "new@example.com");
+
+    expect(result).toBe(true);
+    expect(mockQuery).toHaveBeenCalledWith(
+      expect.stringContaining("SELECT"),
+      expect.arrayContaining(["cus_456"])
+    );
+    expect(mockQuery).toHaveBeenCalledWith(
+      expect.stringContaining("UPDATE"),
+      expect.arrayContaining(["new@example.com", "cus_456"])
+    );
+  });
+
+  it("returns false when key is NOT in cache AND NOT in DB", async () => {
+    mockQuery.mockResolvedValueOnce({ rows: [], rowCount: 0 } as any);
+
+    const result = await updateEmailByCustomer("cus_nonexistent", "new@example.com");
+
+    expect(result).toBe(false);
+    const updateCalls = mockQuery.mock.calls.filter(c => (c[0] as string).includes("UPDATE"));
+    expect(updateCalls).toHaveLength(0);
+  });
+});
+
+describe("updateKeyEmail DB fallback (BUG-109)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("returns true and updates DB when key is NOT in cache but IS in DB", async () => {
+    mockQuery
+      .mockResolvedValueOnce({
+        rows: [{
+          key: "df_pro_xyz789",
+          tier: "pro",
+          email: "old@example.com",
+          created_at: "2026-01-01T00:00:00.000Z",
+          stripe_customer_id: "cus_789",
+        }],
+        rowCount: 1,
+      } as any)
+      .mockResolvedValueOnce({ rows: [], rowCount: 1 } as any); // UPDATE
+
+    const result = await updateKeyEmail("df_pro_xyz789", "new@example.com");
+
+    expect(result).toBe(true);
+    expect(mockQuery).toHaveBeenCalledWith(
+      expect.stringContaining("SELECT"),
+      expect.arrayContaining(["df_pro_xyz789"])
+    );
+    expect(mockQuery).toHaveBeenCalledWith(
+      expect.stringContaining("UPDATE"),
+      expect.arrayContaining(["new@example.com", "df_pro_xyz789"])
+    );
+  });
+
+  it("returns false when key is NOT in cache AND NOT in DB", async () => {
+    mockQuery.mockResolvedValueOnce({ rows: [], rowCount: 0 } as any);
+
+    const result = await updateKeyEmail("df_pro_nonexistent", "new@example.com");
+
+    expect(result).toBe(false);
+    const updateCalls = mockQuery.mock.calls.filter(c => (c[0] as string).includes("UPDATE"));
+    expect(updateCalls).toHaveLength(0);
+  });
+});