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/index.ts

@@ -4,6 +4,7 @@ import { handle as handleRSS } from "./routes/rss";
 import { handle as handleAtom } from "./routes/atom";
 import { handle as handleAdmin } from "./routes/admin";
 import { handle as handleEntry } from "./routes/entries";
+import { handle as handleFiles } from "./routes/files";
 import { handleCloudflareEmail } from "./lib/cloudflare-email";
 import { Env } from "./types";
 
@@ -105,6 +106,7 @@ const api = new Hono();
 const rss = new Hono();
 const atom = new Hono();
 const entries = new Hono();
+const files = new Hono();
 const admin = new Hono();
 
 // Webhook security middleware for /inbound - verify ForwardEmail.net IP
@@ -141,6 +143,9 @@ atom.get("/:feedId", handleAtom);
 // Email entry HTML view (public)
 entries.get("/:feedId/:entryId", handleEntry);
 
+// Attachment file serving (public)
+files.get("/:attachmentId/:filename", handleFiles);
+
 // Admin routes (protected)
 admin.route("/", handleAdmin);
 
@@ -149,6 +154,7 @@ app.route("/api", api);
 app.route("/rss", rss);
 app.route("/atom", atom);
 app.route("/entries", entries);
+app.route("/files", files);
 app.route("/admin", admin);
 
 // Root path redirects to admin dashboard

src/lib/cloudflare-email.ts

@@ -1,6 +1,6 @@
 import PostalMime from "postal-mime";
 import { Env } from "../types";
-import { processEmail } from "./email-processor";
+import { processEmail, RawAttachment } from "./email-processor";
 
 export async function handleCloudflareEmail(
   message: ForwardableEmailMessage,
@@ -21,6 +21,14 @@ export async function handleCloudflareEmail(
       headers[h.key] = h.value;
     }
 
+    const rawAttachments: RawAttachment[] = (email.attachments ?? [])
+      .filter((a) => a.content instanceof ArrayBuffer)
+      .map((a) => ({
+        filename: a.filename || "attachment",
+        contentType: a.mimeType || "application/octet-stream",
+        content: a.content as ArrayBuffer,
+      }));
+
     await processEmail(
       {
         toAddress: message.to,
@@ -30,6 +38,7 @@ export async function handleCloudflareEmail(
         content: email.html ?? email.text ?? "",
         receivedAt: email.date ? new Date(email.date).getTime() : Date.now(),
         headers,
+        attachments: rawAttachments,
       },
       env,
     );

src/lib/email-processor.test.ts

@@ -1,7 +1,7 @@
 import { describe, it, expect, beforeEach } from "vitest";
 import "../test/setup";
-import { createMockEnv } from "../test/setup";
-import { processEmail, ProcessEmailInput } from "./email-processor";
+import { createMockEnv, MockR2 } from "../test/setup";
+import { processEmail, ProcessEmailInput, RawAttachment } from "./email-processor";
 
 const VALID_FEED_ID = "apple.mountain.42";
 const VALID_TO = `${VALID_FEED_ID}@test.getmynews.app`;
@@ -179,3 +179,126 @@ describe("processEmail", () => {
     expect(metadata.emails).toHaveLength(2);
   });
 });
+
+describe("processEmail — attachments", () => {
+  const pdfContent = new TextEncoder().encode("PDF bytes").buffer as ArrayBuffer;
+
+  const pdfAttachment: RawAttachment = {
+    filename: "report.pdf",
+    contentType: "application/pdf",
+    content: pdfContent,
+  };
+
+  it("skips R2 upload when ATTACHMENT_BUCKET is not configured", async () => {
+    const env = createMockEnv();
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({}),
+    );
+    const res = await processEmail(
+      makeInput({ attachments: [pdfAttachment] }),
+      env as any,
+    );
+    expect(res.status).toBe(200);
+
+    const metadata = await env.EMAIL_STORAGE.get(
+      `feed:${VALID_FEED_ID}:metadata`,
+      "json",
+    );
+    const emailData = await env.EMAIL_STORAGE.get(metadata.emails[0].key, "json");
+    expect(emailData.attachments).toBeUndefined();
+  });
+
+  it("uploads attachments to R2 and stores AttachmentData in emailData", async () => {
+    const env = createMockEnv({ withR2: true });
+    const mockR2 = (env as any).ATTACHMENT_BUCKET as unknown as MockR2;
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({}),
+    );
+    const res = await processEmail(
+      makeInput({ attachments: [pdfAttachment] }),
+      env as any,
+    );
+    expect(res.status).toBe(200);
+
+    const metadata = await env.EMAIL_STORAGE.get(
+      `feed:${VALID_FEED_ID}:metadata`,
+      "json",
+    );
+    const emailData = await env.EMAIL_STORAGE.get(metadata.emails[0].key, "json");
+
+    expect(emailData.attachments).toHaveLength(1);
+    expect(emailData.attachments[0].filename).toBe("report.pdf");
+    expect(emailData.attachments[0].contentType).toBe("application/pdf");
+    expect(emailData.attachments[0].size).toBe(pdfContent.byteLength);
+
+    const id = emailData.attachments[0].id;
+    expect(mockR2._has(id)).toBe(true);
+  });
+
+  it("stores attachmentIds in EmailMetadata for trim-time cleanup", async () => {
+    const env = createMockEnv({ withR2: true });
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({}),
+    );
+    await processEmail(makeInput({ attachments: [pdfAttachment] }), env as any);
+
+    const metadata = await env.EMAIL_STORAGE.get(
+      `feed:${VALID_FEED_ID}:metadata`,
+      "json",
+    );
+    expect(metadata.emails[0].attachmentIds).toHaveLength(1);
+    expect(typeof metadata.emails[0].attachmentIds[0]).toBe("string");
+  });
+
+  it("deletes R2 objects when a trimmed email had attachments", async () => {
+    const env = createMockEnv({ withR2: true });
+    const mockR2 = (env as any).ATTACHMENT_BUCKET as unknown as MockR2;
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({}),
+    );
+
+    // Store an old email with attachment in KV and metadata
+    const oldKey = `feed:${VALID_FEED_ID}:111`;
+    const oldAttachmentId = "old-attachment-uuid";
+    const bigContent = "x".repeat(200);
+    const oldEmail = JSON.stringify({
+      subject: "Old",
+      from: "a@b.com",
+      content: bigContent,
+      receivedAt: 111,
+      headers: {},
+      attachments: [{ id: oldAttachmentId, filename: "old.pdf", contentType: "application/pdf", size: 100 }],
+    });
+    await env.EMAIL_STORAGE.put(oldKey, oldEmail);
+
+    // Also put the attachment in mock R2
+    await mockR2.put(oldAttachmentId, new ArrayBuffer(100));
+
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:metadata`,
+      JSON.stringify({
+        emails: [
+          {
+            key: oldKey,
+            subject: "Old",
+            receivedAt: 111,
+            size: oldEmail.length,
+            attachmentIds: [oldAttachmentId],
+          },
+        ],
+      }),
+    );
+
+    // Process with tight size budget to force trimming
+    const tinyEnv = { ...env, FEED_MAX_SIZE_BYTES: "50" };
+    const res = await processEmail(makeInput({ subject: "New" }), tinyEnv as any);
+    expect(res.status).toBe(200);
+
+    // Old attachment should be deleted from R2
+    expect(mockR2._has(oldAttachmentId)).toBe(false);
+  });
+});

src/lib/email-processor.ts

@@ -1,5 +1,11 @@
 import { EmailParser } from "../utils/email-parser";
-import { Env, FeedConfig, FeedMetadata } from "../types";
+import { AttachmentData, EmailMetadata, Env, FeedConfig, FeedMetadata } from "../types";
+
+export interface RawAttachment {
+  filename: string;
+  contentType: string;
+  content: ArrayBuffer;
+}
 
 export interface ProcessEmailInput {
   toAddress: string;
@@ -9,6 +15,7 @@ export interface ProcessEmailInput {
   content: string;
   receivedAt: number;
   headers?: Record<string, string>;
+  attachments?: RawAttachment[];
 }
 
 function normalizeEmail(value: string): string {
@@ -34,6 +41,29 @@ function senderMatchesAllowlist(
   return senderDomain === normalizedDomain;
 }
 
+async function uploadAttachments(
+  attachments: RawAttachment[],
+  bucket: R2Bucket,
+): Promise<AttachmentData[]> {
+  return Promise.all(
+    attachments.map(async (att) => {
+      const id = crypto.randomUUID();
+      await bucket.put(id, att.content, {
+        httpMetadata: {
+          contentType: att.contentType,
+          contentDisposition: `attachment; filename="${att.filename}"`,
+        },
+      });
+      return {
+        id,
+        filename: att.filename,
+        contentType: att.contentType,
+        size: att.content.byteLength,
+      };
+    }),
+  );
+}
+
 export async function processEmail(
   input: ProcessEmailInput,
   env: Env,
@@ -74,12 +104,18 @@ export async function processEmail(
     }
   }
 
+  const storedAttachments: AttachmentData[] =
+    env.ATTACHMENT_BUCKET && input.attachments?.length
+      ? await uploadAttachments(input.attachments, env.ATTACHMENT_BUCKET)
+      : [];
+
   const emailData = {
     subject: input.subject,
     from: input.from,
     content: input.content,
     receivedAt: input.receivedAt,
     headers: input.headers ?? {},
+    ...(storedAttachments.length > 0 ? { attachments: storedAttachments } : {}),
   };
 
   const emailKey = `feed:${feedId}:${Date.now()}`;
@@ -104,24 +140,36 @@ export async function processEmail(
 
   const serialised = JSON.stringify(emailData);
   const serialisedSize = new TextEncoder().encode(serialised).byteLength;
-  feedMetadata.emails.unshift({
+  const newEntry: EmailMetadata = {
     key: emailKey,
     subject: emailData.subject,
     receivedAt: emailData.receivedAt,
     size: serialisedSize,
-  });
+    ...(storedAttachments.length > 0
+      ? { attachmentIds: storedAttachments.map((a) => a.id) }
+      : {}),
+  };
+  feedMetadata.emails.unshift(newEntry);
 
   let totalSize = feedMetadata.emails.reduce((sum, e) => sum + (e.size ?? 0), 0);
-  const toDelete: string[] = [];
+  const toDelete: EmailMetadata[] = [];
   while (totalSize > maxBytes && feedMetadata.emails.length > 1) {
     const dropped = feedMetadata.emails.pop()!;
     totalSize -= dropped.size ?? 0;
-    toDelete.push(dropped.key);
+    toDelete.push(dropped);
   }
 
+  const r2Deletions =
+    env.ATTACHMENT_BUCKET && toDelete.length > 0
+      ? toDelete
+          .flatMap((e) => e.attachmentIds ?? [])
+          .map((id) => env.ATTACHMENT_BUCKET!.delete(id))
+      : [];
+
   await Promise.all([
     env.EMAIL_STORAGE.put(feedMetadataKey, JSON.stringify(feedMetadata)),
-    ...toDelete.map((k) => env.EMAIL_STORAGE.delete(k)),
+    ...toDelete.map((e) => env.EMAIL_STORAGE.delete(e.key)),
+    ...r2Deletions,
   ]);
 
   console.log(`Successfully processed email for feed ${feedId}`);

src/lib/forwardemail.ts

@@ -1,6 +1,16 @@
 import { EmailParser } from "../utils/email-parser";
 import { Env } from "../types";
-import { processEmail } from "./email-processor";
+import { processEmail, RawAttachment } from "./email-processor";
+
+export interface ForwardEmailAttachment {
+  filename?: string;
+  contentType?: string;
+  size?: number;
+  content?:
+    | { type: "Buffer"; data: number[] }
+    | ArrayBuffer
+    | ArrayBufferView;
+}
 
 export interface ForwardEmailPayload {
   recipients?: string[];
@@ -17,7 +27,7 @@ export interface ForwardEmailPayload {
   headerLines?: Array<{ key: string; line: string }>;
   headers?: string;
   raw?: string;
-  attachments?: Array<any>;
+  attachments?: ForwardEmailAttachment[];
 }
 
 function normalizeEmail(value: string): string {
@@ -41,12 +51,36 @@ function extractSenderAddresses(payload: ForwardEmailPayload): string[] {
   return Array.from(new Set(matches.map(normalizeEmail)));
 }
 
+function toArrayBuffer(
+  content: ForwardEmailAttachment["content"],
+): ArrayBuffer | null {
+  if (!content) return null;
+  if (content instanceof ArrayBuffer) return content;
+  if (ArrayBuffer.isView(content)) return (content as ArrayBufferView).buffer as ArrayBuffer;
+  if (typeof content === "object" && content.type === "Buffer" && Array.isArray(content.data)) {
+    return Uint8Array.from(content.data).buffer as ArrayBuffer;
+  }
+  return null;
+}
+
 export async function handleForwardEmail(
   payload: ForwardEmailPayload,
   env: Env,
 ): Promise<Response> {
   const emailData = EmailParser.parseForwardEmailPayload(payload);
 
+  const rawAttachments: RawAttachment[] = (payload.attachments ?? [])
+    .map((a) => {
+      const buffer = toArrayBuffer(a.content);
+      if (!buffer) return null;
+      return {
+        filename: a.filename || "attachment",
+        contentType: a.contentType || "application/octet-stream",
+        content: buffer,
+      };
+    })
+    .filter((a): a is RawAttachment => a !== null);
+
   return processEmail(
     {
       toAddress: payload.recipients?.[0] || "",
@@ -56,6 +90,7 @@ export async function handleForwardEmail(
       content: emailData.content,
       receivedAt: emailData.receivedAt,
       headers: emailData.headers,
+      attachments: rawAttachments,
     },
     env,
   );

src/routes/admin.ts

@@ -1908,7 +1908,7 @@ async function deleteFeedFastDetailed(
 async function purgeFeedKeysStep(
   emailStorage: KVNamespace,
   feedId: string,
-  options: { cursor?: string; limit?: number } = {},
+  options: { cursor?: string; limit?: number; bucket?: R2Bucket } = {},
 ): Promise<{
   deletedKeys: string[];
   failedKeys: string[];
@@ -1921,6 +1921,33 @@ async function purgeFeedKeysStep(
 
   const listed = await emailStorage.list({ prefix, cursor, limit });
   const keys = (listed.keys || []).map((k) => k.name);
+
+  // Collect R2 attachment IDs from email entries before deleting
+  if (options.bucket && keys.length > 0) {
+    const emailKeys = keys.filter((k) => {
+      const suffix = k.slice(prefix.length);
+      return suffix !== "config" && suffix !== "metadata";
+    });
+    if (emailKeys.length > 0) {
+      const emailDataResults = await Promise.allSettled(
+        emailKeys.map((k) =>
+          emailStorage.get(k, { type: "json" }) as Promise<EmailData | null>,
+        ),
+      );
+      const attachmentIds = emailDataResults
+        .filter(
+          (r): r is PromiseFulfilledResult<EmailData | null> =>
+            r.status === "fulfilled",
+        )
+        .flatMap((r) => r.value?.attachments?.map((a) => a.id) ?? []);
+      if (attachmentIds.length > 0) {
+        await Promise.allSettled(
+          attachmentIds.map((id) => options.bucket!.delete(id)),
+        );
+      }
+    }
+  }
+
   const { ok, failed } = await deleteKeysWithConcurrency(
     emailStorage,
     keys,
@@ -1949,7 +1976,7 @@ app.post("/feeds/:feedId/delete", async (c) => {
 
     // Best-effort cleanup in the background so the request stays fast.
     // Use the UI purge endpoint for full, user-visible progress.
-    waitUntilSafe(c, purgeFeedKeysStep(emailStorage, feedId));
+    waitUntilSafe(c, purgeFeedKeysStep(emailStorage, feedId, { bucket: env.ATTACHMENT_BUCKET }));
     if (wantsJson) {
       return c.json({ ok: true, feedId });
     }
@@ -1987,6 +2014,7 @@ app.post("/feeds/:feedId/purge", async (c) => {
     const step = await purgeFeedKeysStep(emailStorage, feedId, {
       cursor,
       limit,
+      bucket: env.ATTACHMENT_BUCKET,
     });
 
     return c.json({
@@ -3420,15 +3448,18 @@ app.post("/emails/:emailKey/delete", async (c) => {
       return c.text("Feed ID is required", 400);
     }
 
-    // Delete the email
-    await emailStorage.delete(emailKey);
-
-    // Remove the email from the feed metadata
+    // Load metadata first to collect attachment IDs for R2 cleanup
     const feedMetadataKey = `feed:${feedId}:metadata`;
     const feedMetadata = (await emailStorage.get(feedMetadataKey, {
       type: "json",
     })) as FeedMetadata | null;
 
+    const attachmentIds =
+      feedMetadata?.emails.find((e) => e.key === emailKey)?.attachmentIds ?? [];
+
+    // Delete the email
+    await emailStorage.delete(emailKey);
+
     if (feedMetadata) {
       // Filter out the deleted email
       feedMetadata.emails = feedMetadata.emails.filter(
@@ -3439,6 +3470,13 @@ app.post("/emails/:emailKey/delete", async (c) => {
       await emailStorage.put(feedMetadataKey, JSON.stringify(feedMetadata));
     }
 
+    // Best-effort R2 attachment cleanup
+    if (env.ATTACHMENT_BUCKET && attachmentIds.length > 0) {
+      await Promise.allSettled(
+        attachmentIds.map((id) => env.ATTACHMENT_BUCKET!.delete(id)),
+      );
+    }
+
     if (wantsJson) {
       return c.json({ ok: true, emailKey, feedId });
     }
@@ -3508,6 +3546,13 @@ app.post("/feeds/:feedId/emails/bulk-delete", async (c) => {
       }
 
       const candidates = emailKeys.filter((key) => allowedKeys.has(key));
+
+      // Collect attachment IDs from metadata before deleting (no extra KV reads needed)
+      const candidateSet = new Set(candidates);
+      const r2AttachmentIds = feedMetadata.emails
+        .filter((e) => candidateSet.has(e.key))
+        .flatMap((e) => e.attachmentIds ?? []);
+
       const { ok: deletedOk, failed: failedEmailKeys } =
         await deleteKeysWithConcurrency(emailStorage, candidates, 35);
 
@@ -3517,6 +3562,13 @@ app.post("/feeds/:feedId/emails/bulk-delete", async (c) => {
       );
       await emailStorage.put(feedMetadataKey, JSON.stringify(feedMetadata));
 
+      // Best-effort R2 attachment cleanup
+      if (env.ATTACHMENT_BUCKET && r2AttachmentIds.length > 0) {
+        await Promise.allSettled(
+          r2AttachmentIds.map((id) => env.ATTACHMENT_BUCKET!.delete(id)),
+        );
+      }
+
       return c.json({
         ok: failedEmailKeys.length === 0,
         deletedEmailKeys: deletedOk,

src/routes/files.test.ts

@@ -0,0 +1,103 @@
+import { describe, it, expect, beforeEach } from "vitest";
+import "../test/setup";
+import { createMockEnv, MockR2 } from "../test/setup";
+import { Hono } from "hono";
+import { handle as handleFiles } from "./files";
+
+async function request(
+  env: ReturnType<typeof createMockEnv>,
+  path: string,
+): Promise<Response> {
+  const app = new Hono();
+  const files = new Hono();
+  files.get("/:attachmentId/:filename", handleFiles);
+  app.route("/files", files);
+  return app.request(path, {}, env as any);
+}
+
+describe("GET /files/:attachmentId/:filename", () => {
+  let envNoR2: ReturnType<typeof createMockEnv>;
+  let envWithR2: ReturnType<typeof createMockEnv>;
+  let mockR2: MockR2;
+
+  beforeEach(() => {
+    envNoR2 = createMockEnv();
+    envWithR2 = createMockEnv({ withR2: true });
+    mockR2 = (envWithR2 as any).ATTACHMENT_BUCKET as unknown as MockR2;
+  });
+
+  it("returns 404 when ATTACHMENT_BUCKET is not configured", async () => {
+    const res = await request(envNoR2, "/files/some-id/file.pdf");
+    expect(res.status).toBe(404);
+    expect(await res.text()).toContain("not configured");
+  });
+
+  it("returns 404 when attachment ID is not found in R2", async () => {
+    const res = await request(envWithR2, "/files/unknown-id/file.pdf");
+    expect(res.status).toBe(404);
+    expect(await res.text()).toBe("Not found");
+  });
+
+  it("returns 200 with stored content when attachment exists", async () => {
+    const content = new TextEncoder().encode("PDF content").buffer as ArrayBuffer;
+    await mockR2.put("test-uuid", content, {
+      httpMetadata: { contentType: "application/pdf" },
+    });
+
+    const res = await request(envWithR2, "/files/test-uuid/report.pdf");
+    expect(res.status).toBe(200);
+  });
+
+  it("returns correct Content-Type from stored httpMetadata", async () => {
+    const content = new TextEncoder().encode("data").buffer as ArrayBuffer;
+    await mockR2.put("img-uuid", content, {
+      httpMetadata: { contentType: "image/png" },
+    });
+
+    const res = await request(envWithR2, "/files/img-uuid/photo.png");
+    expect(res.status).toBe(200);
+    expect(res.headers.get("Content-Type")).toContain("image/png");
+  });
+
+  it("sets Cache-Control immutable header", async () => {
+    const content = new TextEncoder().encode("data").buffer as ArrayBuffer;
+    await mockR2.put("cache-uuid", content, {
+      httpMetadata: { contentType: "application/pdf" },
+    });
+
+    const res = await request(envWithR2, "/files/cache-uuid/doc.pdf");
+    expect(res.headers.get("Cache-Control")).toBe(
+      "public, max-age=31536000, immutable",
+    );
+  });
+
+  it("sets Content-Disposition from httpMetadata when present", async () => {
+    const content = new TextEncoder().encode("data").buffer as ArrayBuffer;
+    await mockR2.put("disp-uuid", content, {
+      httpMetadata: {
+        contentType: "application/pdf",
+        contentDisposition: 'attachment; filename="stored.pdf"',
+      },
+    });
+
+    const res = await request(envWithR2, "/files/disp-uuid/other.pdf");
+    expect(res.headers.get("Content-Disposition")).toBe(
+      'attachment; filename="stored.pdf"',
+    );
+  });
+
+  it("falls back to URL filename for Content-Disposition when not in httpMetadata", async () => {
+    const content = new TextEncoder().encode("data").buffer as ArrayBuffer;
+    await mockR2.put("fallback-uuid", content, {
+      httpMetadata: { contentType: "text/plain" },
+    });
+
+    const res = await request(
+      envWithR2,
+      "/files/fallback-uuid/hello%20world.txt",
+    );
+    expect(res.headers.get("Content-Disposition")).toBe(
+      'attachment; filename="hello world.txt"',
+    );
+  });
+});

src/routes/files.ts

@@ -0,0 +1,33 @@
+import { Context } from "hono";
+import { Env } from "../types";
+
+export async function handle(c: Context): Promise<Response> {
+  const env = c.env as unknown as Env;
+
+  if (!env.ATTACHMENT_BUCKET) {
+    return new Response("Attachment storage not configured", { status: 404 });
+  }
+
+  const attachmentId = c.req.param("attachmentId");
+  const filename = c.req.param("filename");
+
+  const object = await env.ATTACHMENT_BUCKET.get(attachmentId);
+
+  if (!object) {
+    return new Response("Not found", { status: 404 });
+  }
+
+  const headers = new Headers();
+  object.writeHttpMetadata(headers);
+  headers.set("etag", object.httpEtag);
+  headers.set("Cache-Control", "public, max-age=31536000, immutable");
+
+  if (!headers.get("Content-Disposition")) {
+    headers.set(
+      "Content-Disposition",
+      `attachment; filename="${decodeURIComponent(filename)}"`,
+    );
+  }
+
+  return new Response(object.body, { headers });
+}

src/test/setup.ts

@@ -157,12 +157,92 @@ afterEach(() => {
   server.resetHandlers();
 });
 
+/**
+ * Mock R2 bucket implementation
+ * Simulates Cloudflare Workers R2 storage using an in-memory Map
+ */
+export class MockR2 {
+  private store: Map<
+    string,
+    {
+      body: ArrayBuffer;
+      httpMetadata?: { contentType?: string; contentDisposition?: string };
+      httpEtag: string;
+    }
+  > = new Map();
+
+  async put(
+    key: string,
+    value: ReadableStream | ArrayBuffer | ArrayBufferView | string | null | Blob,
+    options?: {
+      httpMetadata?: { contentType?: string; contentDisposition?: string };
+    },
+  ) {
+    let buffer: ArrayBuffer;
+    if (value instanceof ArrayBuffer) {
+      buffer = value;
+    } else if (typeof value === "string") {
+      buffer = new TextEncoder().encode(value).buffer as ArrayBuffer;
+    } else if (ArrayBuffer.isView(value)) {
+      buffer = value.buffer as ArrayBuffer;
+    } else {
+      buffer = new ArrayBuffer(0);
+    }
+    this.store.set(key, {
+      body: buffer,
+      httpMetadata: options?.httpMetadata,
+      httpEtag: `"mock-etag-${key}"`,
+    });
+  }
+
+  async get(key: string) {
+    const entry = this.store.get(key);
+    if (!entry) return null;
+    return {
+      key,
+      body: new ReadableStream({
+        start(controller) {
+          controller.enqueue(new Uint8Array(entry.body));
+          controller.close();
+        },
+      }),
+      httpEtag: entry.httpEtag,
+      httpMetadata: entry.httpMetadata,
+      size: entry.body.byteLength,
+      arrayBuffer: async () => entry.body,
+      text: async () => new TextDecoder().decode(entry.body),
+      writeHttpMetadata: (headers: Headers) => {
+        if (entry.httpMetadata?.contentType) {
+          headers.set("Content-Type", entry.httpMetadata.contentType);
+        }
+        if (entry.httpMetadata?.contentDisposition) {
+          headers.set("Content-Disposition", entry.httpMetadata.contentDisposition);
+        }
+      },
+    };
+  }
+
+  async delete(keys: string | string[]) {
+    const arr = Array.isArray(keys) ? keys : [keys];
+    for (const k of arr) {
+      this.store.delete(k);
+    }
+  }
+
+  _has(key: string) {
+    return this.store.has(key);
+  }
+}
+
 /**
  * Create a mock environment for testing
  * @returns Mock environment with KV storage and configuration
  */
-export const createMockEnv = () => ({
+export const createMockEnv = (options: { withR2?: boolean } = {}) => ({
   EMAIL_STORAGE: new MockKV(),
   DOMAIN: "test.getmynews.app",
   ADMIN_PASSWORD: "test-password",
+  ...(options.withR2
+    ? { ATTACHMENT_BUCKET: new MockR2() as unknown as R2Bucket }
+    : {}),
 });

src/types/index.ts

@@ -3,11 +3,20 @@ export interface Env {
   EMAIL_STORAGE: KVNamespace;
   ADMIN_PASSWORD: string;
   DOMAIN: string;
+  ATTACHMENT_BUCKET?: R2Bucket;
   FEED_MAX_SIZE_BYTES?: string;
   PROXY_TRUSTED_IPS?: string;
   PROXY_AUTH_SECRET?: string;
 }
 
+// Stored attachment metadata (bytes live in R2, keyed by id)
+export interface AttachmentData {
+  id: string;
+  filename: string;
+  contentType: string;
+  size: number;
+}
+
 // Email interface for stored emails
 export interface EmailData {
   subject: string;
@@ -15,6 +24,7 @@ export interface EmailData {
   content: string;
   receivedAt: number;
   headers: Record<string, string>;
+  attachments?: AttachmentData[];
 }
 
 // Feed configuration interface
@@ -41,6 +51,7 @@ export interface EmailMetadata {
   subject: string;
   receivedAt: number;
   size?: number;
+  attachmentIds?: string[];
 }
 
 // Feed list interface

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,
     });
   }