downloads: serve Nook delta files the Sparkle updater fetches

The v0.10.0 publish stopped at the enclosure check: the appcast names
Nook17-9.delta / Nook17-10.delta, and the proxy 400'd both with
'Invalid file format' while the TheNook DMG passed. Sparkle names delta
files after the app bundle, not the DMG, so the prefix allowlist needs
'Nook' alongside 'TheNook'. Both deltas sat in S3 the whole time; the
appcast was never published and the live one still serves 0.9.0.

Adds a static source-audit regression test in the repo's downloads.test
pattern; proven red against the unfixed allowlist.

Tests: bun test src/routes/api/downloads/filename.test.ts

NOOK-337

Co-Authored-By: glm-5.3-flash <noreply@neuralwatt.com>

src/routes/api/downloads/[filename].ts

@@ -8,7 +8,10 @@ import { env } from "~/env/server";
  *
  * Handles:
  * - Full DMG files: /api/downloads/Gaze-0.2.2.dmg, /api/downloads/InputHalo-0.1.0.dmg
- * - Delta updates: /api/downloads/Gaze3-2.delta, /api/downloads/InputHalo3-2.delta
+ * - Delta updates: /api/downloads/Gaze3-2.delta, /api/downloads/Nook17-9.delta
+ *
+ * The Nook delta files are named after the app bundle ("Nook"), not the DMG
+ * ("TheNook"), so both prefixes must be allowed (NOOK-337).
  *
  * URL: https://freno.me/api/downloads/[filename]
  */
@@ -24,7 +27,7 @@ export async function GET(event: APIEvent) {
     });
   }
 
-  const validPrefixes = ["Gaze", "InputHalo", "TheNook"];
+  const validPrefixes = ["Gaze", "InputHalo", "TheNook", "Nook"];
   const isValidPrefix = validPrefixes.some((prefix) => filename.startsWith(prefix));
   if (
     !isValidPrefix ||

src/routes/api/downloads/filename.test.ts

@@ -0,0 +1,38 @@
+/**
+ * Regression test for the downloads proxy filename allowlist (NOOK-337).
+ *
+ * The v0.10.0 publish failed its CI enclosure check because Sparkle names
+ * delta files after the app bundle ("Nook17-9.delta") while the DMG is named
+ * "TheNook-*.dmg" — and "Nook" was missing from the allowlist, so every Nook
+ * delta request 400'd with "Invalid file format" while the DMG passed.
+ *
+ * The route hits S3 and cannot be unit-tested under bun:test, so this is a
+ * STATIC SOURCE AUDIT — the same pattern the downloads.test.ts regressions
+ * use.
+ */
+import { describe, it, expect } from "bun:test";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+
+const SOURCE = readFileSync(
+  join(import.meta.dir, "[filename].ts"),
+  "utf8"
+);
+
+describe("Downloads proxy filename allowlist (NOOK-337)", () => {
+  it("allows the Nook app-bundle prefix used by Sparkle delta names", () => {
+    expect(SOURCE).toContain('"Nook"');
+  });
+
+  it("still allows every previously served prefix", () => {
+    for (const prefix of ["Gaze", "InputHalo", "TheNook"]) {
+      expect(SOURCE).toContain(`"${prefix}"`);
+    }
+  });
+
+  it("still serves the extensions Sparkle fetches", () => {
+    for (const ext of [".dmg", ".delta", ".zip"]) {
+      expect(SOURCE).toContain(`"${ext}"`);
+    }
+  });
+});