diff --git a/apps/backend/src/app.ts b/apps/backend/src/app.ts
index 1d6b6ac..4b0c723 100644
--- a/apps/backend/src/app.ts
+++ b/apps/backend/src/app.ts
@@ -13,6 +13,7 @@ import { usersRouter } from './routes/users.js';
 import { treasuryRouter } from './routes/treasury.js';
 import { filesRouter } from './routes/files.js';
 import { pushRouter } from './routes/push.js';
+import { uploadsRouter } from './routes/uploads.js';
 import { requireAuth, type AuthRequest } from './middleware/auth.js';
 
 const packageJson = JSON.parse(
@@ -55,6 +56,7 @@ app.use('/users', usersRouter);
 app.use('/treasury', treasuryRouter);
 app.use('/files', filesRouter);
 app.use('/push', pushRouter);
+app.use('/uploads', uploadsRouter);
 
 app.get('/me', requireAuth, (req, res) => {
   res.json({ user: (req as AuthRequest).auth });
diff --git a/apps/backend/src/db/schema.ts b/apps/backend/src/db/schema.ts
index 0ec572c..e45346f 100644
--- a/apps/backend/src/db/schema.ts
+++ b/apps/backend/src/db/schema.ts
@@ -53,6 +53,22 @@ export const contentTypeEnum = pgEnum('content_type', [
   'system',
 ]);
 
+export const fileStatusEnum = pgEnum('file_status', ['pending', 'ready']);
+
+export const files = pgTable('files', {
+  id: uuid('id').primaryKey(),
+  conversationId: uuid('conversation_id')
+    .notNull()
+    .references(() => conversations.id, { onDelete: 'cascade' }),
+  uploaderId: uuid('uploader_id')
+    .notNull()
+    .references(() => users.id, { onDelete: 'cascade' }),
+  size: integer('size').notNull(),
+  sha256: text('sha256'),
+  status: fileStatusEnum('status').notNull().default('pending'),
+  createdAt: timestamp('created_at').notNull().defaultNow(),
+});
+
 export const conversationMembers = pgTable('conversation_members', {
   id: uuid('id').primaryKey().defaultRandom(),
   conversationId: uuid('conversation_id')
@@ -293,6 +309,15 @@ export const usersRelations = relations(users, ({ many }) => ({
   messages: many(messages),
   transfers: many(tokenTransfers),
   devices: many(devices),
+  files: many(files),
+}));
+
+export const filesRelations = relations(files, ({ one }) => ({
+  conversation: one(conversations, {
+    fields: [files.conversationId],
+    references: [conversations.id],
+  }),
+  uploader: one(users, { fields: [files.uploaderId], references: [users.id] }),
 }));
 
 export const walletsRelations = relations(wallets, ({ one }) => ({
@@ -304,6 +329,7 @@ export const conversationsRelations = relations(conversations, ({ many }) => ({
   messages: many(messages),
   transfers: many(tokenTransfers),
   treasuryProposals: many(treasuryProposals),
+  files: many(files),
 }));
 
 export const conversationMembersRelations = relations(conversationMembers, ({ one }) => ({
@@ -414,3 +440,5 @@ export type OneTimePreKey = typeof oneTimePreKeys.$inferSelect;
 export type NewOneTimePreKey = typeof oneTimePreKeys.$inferInsert;
 export type UserDevice = typeof userDevices.$inferSelect;
 export type NewUserDevice = typeof userDevices.$inferInsert;
+export type FileRecord = typeof files.$inferSelect;
+export type NewFileRecord = typeof files.$inferInsert;
diff --git a/apps/backend/src/index.ts b/apps/backend/src/index.ts
index d94893c..3793fff 100644
--- a/apps/backend/src/index.ts
+++ b/apps/backend/src/index.ts
@@ -33,6 +33,7 @@ import {
   runForever as runStellarListener,
 } from './services/stellarListener.js';
 import { loadEnv } from './config.js';
+import { startGarbageCollection } from './services/garbageCollection.js';
 
 dotenv.config();
 
@@ -236,6 +237,7 @@ async function attachRedisAdapter(): Promise<void> {
 const PORT = process.env['PORT'] ?? 3001;
 httpServer.listen(PORT, () => {
   console.log(`Backend server running on port ${PORT}`);
+  startGarbageCollection();
 });
 
 // Attach the Redis adapter after listen() so the API is reachable even if
diff --git a/apps/backend/src/routes/uploads.ts b/apps/backend/src/routes/uploads.ts
new file mode 100644
index 0000000..72abc65
--- /dev/null
+++ b/apps/backend/src/routes/uploads.ts
@@ -0,0 +1,119 @@
+import { Router } from 'express';
+import type { IRouter } from 'express';
+import { eq, and } from 'drizzle-orm';
+import { db } from '../db/index.js';
+import { conversationMembers, files } from '../db/schema.js';
+import { requireAuth, type AuthRequest } from '../middleware/auth.js';
+import { S3Client, PutObjectCommand, HeadObjectCommand } from '@aws-sdk/client-s3';
+import { getSignedUrl } from '@aws-sdk/s3-request-presigner';
+
+export const uploadsRouter: IRouter = Router();
+uploadsRouter.use(requireAuth);
+
+const s3 = new S3Client({
+  region: process.env['AWS_REGION'] || 'us-east-1',
+});
+const bucketName = process.env['AWS_BUCKET'] || 'clicked-files';
+
+uploadsRouter.post('/', async (req: AuthRequest, res) => {
+  const userId = req.auth!.userId;
+  const { fileId, conversationId, size, sha256 } = req.body;
+
+  if (!fileId || !conversationId || typeof size !== 'number') {
+    res.status(400).json({ error: 'fileId, conversationId, and size are required' });
+    return;
+  }
+
+  const membership = await db.query.conversationMembers.findFirst({
+    where: and(
+      eq(conversationMembers.conversationId, conversationId),
+      eq(conversationMembers.userId, userId),
+    ),
+  });
+
+  if (!membership) {
+    res.status(403).json({ error: 'Not authorized for this conversation' });
+    return;
+  }
+
+  // Insert pending file record
+  try {
+    await db.insert(files).values({
+      id: fileId,
+      conversationId,
+      uploaderId: userId,
+      size,
+      sha256: sha256 || null,
+      status: 'pending',
+    });
+  } catch (err) {
+    res.status(409).json({ error: 'File upload already initiated' });
+    return;
+  }
+
+  try {
+    const command = new PutObjectCommand({
+      Bucket: bucketName,
+      Key: fileId,
+    });
+    // Signed URL for uploading directly to S3
+    const presignedUrl = await getSignedUrl(s3, command, { expiresIn: 900 });
+    res.json({ url: presignedUrl });
+  } catch {
+    res.status(500).json({ error: 'Failed to generate upload URL' });
+  }
+});
+
+uploadsRouter.post('/:fileId/complete', async (req: AuthRequest, res) => {
+  const userId = req.auth!.userId;
+  const fileId = req.params['fileId'] as string;
+
+  if (!fileId) {
+    res.status(400).json({ error: 'File id is required' });
+    return;
+  }
+
+  const file = await db.query.files.findFirst({
+    where: eq(files.id, fileId),
+  });
+
+  if (!file) {
+    res.status(404).json({ error: 'File not found' });
+    return;
+  }
+
+  if (file.uploaderId !== userId) {
+    res.status(403).json({ error: 'Not authorized to complete this upload' });
+    return;
+  }
+
+  if (file.status === 'ready') {
+    res.json({ success: true, message: 'Already completed' });
+    return;
+  }
+
+  try {
+    const headCommand = new HeadObjectCommand({
+      Bucket: bucketName,
+      Key: fileId,
+    });
+    const headResponse = await s3.send(headCommand);
+
+    if (headResponse.ContentLength !== file.size) {
+       res.status(400).json({ error: 'Size mismatch', details: 'File size in storage does not match declared size' });
+       return;
+    }
+
+    await db.update(files)
+      .set({ status: 'ready' })
+      .where(eq(files.id, fileId));
+
+    res.json({ success: true, message: 'Upload confirmed' });
+  } catch (err: any) {
+    if (err.name === 'NotFound') {
+      res.status(400).json({ error: 'File not found in storage' });
+    } else {
+      res.status(500).json({ error: 'Failed to verify file upload' });
+    }
+  }
+});
diff --git a/apps/backend/src/services/garbageCollection.ts b/apps/backend/src/services/garbageCollection.ts
new file mode 100644
index 0000000..252a261
--- /dev/null
+++ b/apps/backend/src/services/garbageCollection.ts
@@ -0,0 +1,54 @@
+import { lt, and, eq } from 'drizzle-orm';
+import { S3Client, DeleteObjectCommand } from '@aws-sdk/client-s3';
+import { db } from '../db/index.js';
+import { files } from '../db/schema.js';
+
+const s3 = new S3Client({
+  region: process.env['AWS_REGION'] || 'us-east-1',
+});
+const bucketName = process.env['AWS_BUCKET'] || 'clicked-files';
+
+let gcInterval: ReturnType<typeof setInterval> | null = null;
+
+export async function runGarbageCollection() {
+  const ONE_DAY_AGO = new Date(Date.now() - 24 * 60 * 60 * 1000);
+  
+  try {
+    const oldPendingFiles = await db.query.files.findMany({
+      where: and(
+        eq(files.status, 'pending'),
+        lt(files.createdAt, ONE_DAY_AGO)
+      ),
+    });
+
+    for (const file of oldPendingFiles) {
+      try {
+        await s3.send(new DeleteObjectCommand({
+          Bucket: bucketName,
+          Key: file.id,
+        }));
+      } catch (err) {
+        console.error(`[GC] Failed to delete file ${file.id} from S3`, err);
+      }
+      
+      await db.delete(files).where(eq(files.id, file.id));
+    }
+  } catch (err) {
+    console.error('[GC] Garbage collection failed', err);
+  }
+}
+
+export function startGarbageCollection() {
+  if (gcInterval) return;
+  // Run every hour
+  gcInterval = setInterval(() => {
+    runGarbageCollection().catch(console.error);
+  }, 60 * 60 * 1000);
+}
+
+export function stopGarbageCollection() {
+  if (gcInterval) {
+    clearInterval(gcInterval);
+    gcInterval = null;
+  }
+}
diff --git a/apps/backend/src/socket/messaging.ts b/apps/backend/src/socket/messaging.ts
index 5426137..0488850 100644
--- a/apps/backend/src/socket/messaging.ts
+++ b/apps/backend/src/socket/messaging.ts
@@ -8,6 +8,7 @@ import {
   messages,
   messageEnvelopes,
   userDevices,
+  files,
 } from '../db/schema.js';
 import type { AuthSocket } from '../middleware/socketAuth.js';
 import { invalidateConversationCaches } from '../lib/conversationCache.js';
@@ -133,6 +134,18 @@ export function registerMessagingHandlers(io: Server, socket: AuthSocket): void
         return;
       }
 
+      const isFile = contentType && contentType !== 'text/plain';
+      if (isFile) {
+        const file = await db.query.files.findFirst({
+          where: eq(files.id, messageId),
+        });
+
+        if (!file || file.status !== 'ready') {
+          socket.emit('error', { event: 'send_message', message: 'Referenced file is not ready or not found' });
+          return;
+        }
+      }
+
       const [message] = await db
         .insert(messages)
         .values({
@@ -174,10 +187,9 @@ export function registerMessagingHandlers(io: Server, socket: AuthSocket): void
           messageId,
           sequenceNumber: message.sequenceNumber,
         });
+        await deliverMessage(io, message, conversationId);
       }
 
-      await deliverMessage(io, message, conversationId);
-
       const members = await db.query.conversationMembers.findMany({
         where: eq(conversationMembers.conversationId, conversationId),
         columns: { userId: true },
@@ -243,6 +255,20 @@ export function registerMessagingHandlers(io: Server, socket: AuthSocket): void
         return;
       }
 
+      const effectiveContentType = contentType || original.contentType;
+      const isFile = effectiveContentType && effectiveContentType !== 'text/plain';
+      
+      if (isFile) {
+        const file = await db.query.files.findFirst({
+          where: eq(files.id, messageId),
+        });
+
+        if (!file || file.status !== 'ready') {
+          socket.emit('error', { event: 'edit_message', message: 'Referenced file is not ready or not found' });
+          return;
+        }
+      }
+
       const [message] = await db
         .insert(messages)
         .values({