fix: resolve all TypeScript strict-mode errors in test files

- convert-sanitized: use 'as Record' cast for optional mock call args
- error-responses: fix module path (database.js → db.js) and mock return type
- recover-initial-db-fallback: fix mock return type (undefined → true)
- render-timing: remove non-existent .prepare property check
- usage-flush: cast mock request objects to any for test setup

Zero tsc --noEmit errors. 608 tests passing.

src/__tests__/convert-sanitized.test.ts

@@ -38,7 +38,7 @@ describe("convert routes use sanitized PDF options", () => {
       .send({ html: "<h1>Test</h1>", format: "a4" });
 
     expect(vi.mocked(renderPdf)).toHaveBeenCalledOnce();
-    const opts = vi.mocked(renderPdf).mock.calls[0][1];
+    const opts = vi.mocked(renderPdf).mock.calls[0]![1] as Record<string, unknown>;
     expect(opts.format).toBe("A4");
   });
 
@@ -51,7 +51,7 @@ describe("convert routes use sanitized PDF options", () => {
       .send({ markdown: "# Test", format: "letter" });
 
     expect(vi.mocked(renderPdf)).toHaveBeenCalledOnce();
-    const opts = vi.mocked(renderPdf).mock.calls[0][1];
+    const opts = vi.mocked(renderPdf).mock.calls[0]![1] as Record<string, unknown>;
     expect(opts.format).toBe("Letter");
   });
 
@@ -64,7 +64,7 @@ describe("convert routes use sanitized PDF options", () => {
       .send({ url: "https://example.com", format: "a3" });
 
     expect(vi.mocked(renderUrlPdf)).toHaveBeenCalledOnce();
-    const opts = vi.mocked(renderUrlPdf).mock.calls[0][1];
+    const opts = vi.mocked(renderUrlPdf).mock.calls[0]![1] as Record<string, unknown>;
     expect(opts.format).toBe("A3");
   });
 });
@@ -79,7 +79,7 @@ describe("demo routes use sanitized PDF options", () => {
       .send({ html: "<h1>Test</h1>", format: "a4" });
 
     expect(vi.mocked(renderPdf)).toHaveBeenCalledOnce();
-    const opts = vi.mocked(renderPdf).mock.calls[0][1];
+    const opts = vi.mocked(renderPdf).mock.calls[0]![1] as Record<string, unknown>;
     expect(opts.format).toBe("A4");
   });
 
@@ -92,7 +92,7 @@ describe("demo routes use sanitized PDF options", () => {
       .send({ markdown: "# Test", format: "a4" });
 
     expect(vi.mocked(renderPdf)).toHaveBeenCalledOnce();
-    const opts = vi.mocked(renderPdf).mock.calls[0][1];
+    const opts = vi.mocked(renderPdf).mock.calls[0]![1] as Record<string, unknown>;
     expect(opts.format).toBe("A4");
   });
 });

src/__tests__/error-responses.test.ts

@@ -226,12 +226,12 @@ describe("Error Response Security - Admin Cleanup", () => {
     const mockAdminAuth = (req: any, res: any, next: any) => next();
 
     // Mock database functions
-    vi.mock("../services/database.js", () => ({
+    vi.mock("../services/db.js", () => ({
       cleanupStaleData: vi.fn(),
     }));
 
-    const { cleanupStaleData } = await import("../services/database.js");
+    const { cleanupStaleData } = await import("../services/db.js");
-    vi.mocked(cleanupStaleData).mockResolvedValue({ deletedCount: 5 });
+    vi.mocked(cleanupStaleData).mockResolvedValue({ expiredVerifications: 3, orphanedUsage: 2 });
 
     // Create minimal app
     app = express();
@@ -250,7 +250,7 @@ describe("Error Response Security - Admin Cleanup", () => {
   });
 
   it("does not expose error message (no 'message' field)", async () => {
-    const { cleanupStaleData } = await import("../services/database.js");
+    const { cleanupStaleData } = await import("../services/db.js");
     const internalError = new Error("Database connection pool exhausted");
     vi.mocked(cleanupStaleData).mockRejectedValue(internalError);
     

src/__tests__/recover-initial-db-fallback.test.ts

@@ -63,7 +63,7 @@ describe("POST /v1/recover DB fallback (BUG-110)", () => {
     vi.clearAllMocks();
     mockGetAllKeys.mockReturnValue([]);
     mockCreatePending.mockResolvedValue({ code: "123456" } as any);
-    mockSendEmail.mockResolvedValue(undefined);
+    mockSendEmail.mockResolvedValue(true);
   });
 
   it("sends verification email via DB fallback when key not in cache but exists in DB", async () => {

src/__tests__/render-timing.test.ts

@@ -108,7 +108,7 @@ describe("PDF render timing", () => {
       vi.mocked(renderPdf).mockResolvedValue({ pdf: Buffer.from("%PDF-1.4 mock"), durationMs: 30 } as any);
 
       const dbMod = await import("../services/db.js");
-      if (vi.isMockFunction(dbMod.default?.prepare)) {
+      if (vi.isMockFunction((dbMod as Record<string, unknown>).default)) {
         // db is already mocked elsewhere
       }
     });

src/__tests__/usage-flush.test.ts

@@ -20,8 +20,8 @@ describe("flushDirtyEntries – independent key flushing", () => {
     const next = vi.fn();
     const res = { status: vi.fn(() => ({ json: vi.fn() })) };
 
-    usageMod.usageMiddleware({ apiKeyInfo: { key: "key-good" } }, res, next);
+    usageMod.usageMiddleware({ apiKeyInfo: { key: "key-good" } } as any, res as any, next);
-    usageMod.usageMiddleware({ apiKeyInfo: { key: "key-bad" } }, res, next);
+    usageMod.usageMiddleware({ apiKeyInfo: { key: "key-bad" } } as any, res as any, next);
 
     // Track which keys were successfully upserted
     const flushedKeys: string[] = [];