feat: store email attachments in R2 and expose as RSS enclosures

Attachments from incoming emails are uploaded to an optional Cloudflare R2
bucket and exposed as <enclosure> elements in RSS and <link rel="enclosure">
in Atom feeds, served at /files/{id}/{filename} with immutable caching.

R2 is opt-in: if ATTACHMENT_BUCKET is not bound the feature is a no-op.
Attachments are cleaned up from R2 on email/feed deletion and during
size-based feed trimming. Adds MockR2 to the test setup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/utils/feed-generator.test.ts

@@ -21,6 +21,18 @@ const mockEmails: EmailData[] = [
   },
 ];
 
+const mockEmailWithAttachment: EmailData = {
+  ...mockEmails[0],
+  attachments: [
+    {
+      id: "550e8400-e29b-41d4-a716-446655440000",
+      filename: "report.pdf",
+      contentType: "application/pdf",
+      size: 12345,
+    },
+  ],
+};
+
 const BASE_URL = "https://test.getmynews.app";
 const FEED_ID = "abc123";
 
@@ -31,6 +43,25 @@ describe("generateRssFeed", () => {
     expect(result).toContain("<title>Test Newsletter</title>");
   });
 
+  it("includes <enclosure> element for email with attachment", () => {
+    const result = generateRssFeed(mockFeedConfig, [mockEmailWithAttachment], BASE_URL, FEED_ID);
+    expect(result).toContain("<enclosure");
+    expect(result).toContain("550e8400-e29b-41d4-a716-446655440000");
+    expect(result).toContain("report.pdf");
+    expect(result).toContain("application/pdf");
+    expect(result).toContain("12345");
+  });
+
+  it("does not include <enclosure> for email without attachments", () => {
+    const result = generateRssFeed(mockFeedConfig, mockEmails, BASE_URL, FEED_ID);
+    expect(result).not.toContain("<enclosure");
+  });
+
+  it("enclosure URL uses /files/{id}/{filename} scheme", () => {
+    const result = generateRssFeed(mockFeedConfig, [mockEmailWithAttachment], BASE_URL, FEED_ID);
+    expect(result).toContain(`${BASE_URL}/files/550e8400-e29b-41d4-a716-446655440000/report.pdf`);
+  });
+
   it("includes rss self-link in RSS output", () => {
     const result = generateRssFeed(mockFeedConfig, mockEmails, BASE_URL, FEED_ID);
     expect(result).toContain(`${BASE_URL}/rss/${FEED_ID}`);
@@ -104,4 +135,16 @@ describe("generateAtomFeed", () => {
     const result = generateAtomFeed(configWithAuthor, mockEmails, BASE_URL, FEED_ID);
     expect(result).toContain("Bob");
   });
+
+  it("includes enclosure link for email with attachment in Atom feed", () => {
+    const result = generateAtomFeed(mockFeedConfig, [mockEmailWithAttachment], BASE_URL, FEED_ID);
+    expect(result).toContain('rel="enclosure"');
+    expect(result).toContain("550e8400-e29b-41d4-a716-446655440000");
+    expect(result).toContain("report.pdf");
+  });
+
+  it("does not include enclosure link for email without attachments in Atom feed", () => {
+    const result = generateAtomFeed(mockFeedConfig, mockEmails, BASE_URL, FEED_ID);
+    expect(result).not.toContain('rel="enclosure"');
+  });
 });

src/utils/feed-generator.ts

@@ -42,6 +42,7 @@ function buildFeed(
 
   for (const email of emails) {
     const uniqueId = `${email.receivedAt}-${Buffer.from(email.subject).toString("base64").substring(0, 10)}`;
+    const firstAttachment = email.attachments?.[0];
     feed.addItem({
       title: email.subject,
       id: uniqueId,
@@ -50,6 +51,13 @@ function buildFeed(
       content: email.content,
       author: [parseFromAddress(email.from)],
       date: new Date(email.receivedAt),
+      enclosure: firstAttachment
+        ? {
+            url: `${baseUrl}/files/${firstAttachment.id}/${encodeURIComponent(firstAttachment.filename)}`,
+            type: firstAttachment.contentType,
+            length: firstAttachment.size,
+          }
+        : undefined,
     });
   }