diff --git a/App/pelagia-portal/app/api/files/dev/[...key]/route.ts b/App/pelagia-portal/app/api/files/dev/[...key]/route.ts
new file mode 100644
index 0000000..ee3f10e
--- /dev/null
+++ b/App/pelagia-portal/app/api/files/dev/[...key]/route.ts
@@ -0,0 +1,88 @@
+import { auth } from "@/auth";
+import { NextRequest, NextResponse } from "next/server";
+import fs from "fs/promises";
+import path from "path";
+
+const UPLOADS_DIR = path.join(process.cwd(), ".dev-uploads");
+
+function resolveFilePath(keySegments: string[]): string {
+  const relative = path.join(...keySegments);
+  const resolved = path.resolve(UPLOADS_DIR, relative);
+  // Prevent path traversal outside the uploads directory
+  if (!resolved.startsWith(path.resolve(UPLOADS_DIR))) {
+    throw new Error("Invalid path");
+  }
+  return resolved;
+}
+
+export async function PUT(
+  request: NextRequest,
+  { params }: { params: Promise<{ key: string[] }> }
+) {
+  if (process.env.NODE_ENV !== "development") {
+    return NextResponse.json({ error: "Not found" }, { status: 404 });
+  }
+
+  const session = await auth();
+  if (!session?.user) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  const { key } = await params;
+  let filePath: string;
+  try {
+    filePath = resolveFilePath(key);
+  } catch {
+    return NextResponse.json({ error: "Invalid path" }, { status: 400 });
+  }
+
+  await fs.mkdir(path.dirname(filePath), { recursive: true });
+  const buffer = await request.arrayBuffer();
+  await fs.writeFile(filePath, Buffer.from(buffer));
+
+  return new NextResponse(null, { status: 200 });
+}
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ key: string[] }> }
+) {
+  if (process.env.NODE_ENV !== "development") {
+    return NextResponse.json({ error: "Not found" }, { status: 404 });
+  }
+
+  const session = await auth();
+  if (!session?.user) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  const { key } = await params;
+  let filePath: string;
+  try {
+    filePath = resolveFilePath(key);
+  } catch {
+    return NextResponse.json({ error: "Invalid path" }, { status: 400 });
+  }
+
+  let fileBuffer: Buffer;
+  try {
+    fileBuffer = await fs.readFile(filePath) as Buffer;
+  } catch {
+    return NextResponse.json({ error: "File not found" }, { status: 404 });
+  }
+
+  const ext = path.extname(filePath).toLowerCase();
+  const contentTypeMap: Record<string, string> = {
+    ".pdf": "application/pdf",
+    ".png": "image/png",
+    ".jpg": "image/jpeg",
+    ".jpeg": "image/jpeg",
+    ".gif": "image/gif",
+    ".webp": "image/webp",
+  };
+  const contentType = contentTypeMap[ext] ?? "application/octet-stream";
+
+  return new NextResponse(new Uint8Array(fileBuffer), {
+    headers: { "Content-Type": contentType },
+  });
+}
diff --git a/App/pelagia-portal/app/api/files/sign/route.ts b/App/pelagia-portal/app/api/files/sign/route.ts
new file mode 100644
index 0000000..b67dddd
--- /dev/null
+++ b/App/pelagia-portal/app/api/files/sign/route.ts
@@ -0,0 +1,34 @@
+import { auth } from "@/auth";
+import { generateUploadUrl, buildStorageKey } from "@/lib/storage";
+import { NextRequest, NextResponse } from "next/server";
+import { z } from "zod";
+
+const signSchema = z.object({
+  fileName: z.string().min(1),
+  mimeType: z.string().min(1),
+  poId: z.string().min(1),
+  type: z.enum(["po-document", "receipt"]),
+});
+
+export async function POST(request: NextRequest) {
+  const session = await auth();
+  if (!session?.user) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  const body = await request.json();
+  const parsed = signSchema.safeParse(body);
+  if (!parsed.success) {
+    return NextResponse.json({ error: "Invalid request" }, { status: 400 });
+  }
+
+  const { fileName, mimeType, poId, type } = parsed.data;
+  const key = buildStorageKey(type, poId, fileName);
+
+  try {
+    const uploadUrl = await generateUploadUrl(key, mimeType);
+    return NextResponse.json({ uploadUrl, key });
+  } catch {
+    return NextResponse.json({ error: "Failed to generate upload URL" }, { status: 500 });
+  }
+}
diff --git a/App/pelagia-portal/lib/storage.ts b/App/pelagia-portal/lib/storage.ts
new file mode 100644
index 0000000..095f4f8
--- /dev/null
+++ b/App/pelagia-portal/lib/storage.ts
@@ -0,0 +1,54 @@
+import { S3Client, PutObjectCommand, GetObjectCommand } from "@aws-sdk/client-s3";
+import { getSignedUrl } from "@aws-sdk/s3-request-presigner";
+
+const isDev = process.env.NODE_ENV === "development";
+
+function getR2Client() {
+  return new S3Client({
+    region: "auto",
+    endpoint: `https://${process.env.R2_ACCOUNT_ID}.r2.cloudflarestorage.com`,
+    credentials: {
+      accessKeyId: process.env.R2_ACCESS_KEY_ID!,
+      secretAccessKey: process.env.R2_SECRET_ACCESS_KEY!,
+    },
+  });
+}
+
+const DEV_BASE_URL = process.env.NEXTAUTH_URL ?? "http://localhost:3000";
+
+export async function generateUploadUrl(
+  key: string,
+  contentType: string,
+  expiresIn = 300
+): Promise<string> {
+  if (isDev) {
+    return `${DEV_BASE_URL}/api/files/dev/${key}`;
+  }
+  const command = new PutObjectCommand({
+    Bucket: process.env.R2_BUCKET_NAME!,
+    Key: key,
+    ContentType: contentType,
+  });
+  return getSignedUrl(getR2Client(), command, { expiresIn });
+}
+
+export async function generateDownloadUrl(
+  key: string,
+  expiresIn = 3600
+): Promise<string> {
+  if (isDev) {
+    return `${DEV_BASE_URL}/api/files/dev/${key}`;
+  }
+  const command = new GetObjectCommand({ Bucket: process.env.R2_BUCKET_NAME!, Key: key });
+  return getSignedUrl(getR2Client(), command, { expiresIn });
+}
+
+export function buildStorageKey(
+  type: "po-document" | "receipt",
+  poId: string,
+  fileName: string
+): string {
+  const timestamp = Date.now();
+  const safe = fileName.replace(/[^a-zA-Z0-9._-]/g, "_");
+  return `${type}/${poId}/${timestamp}-${safe}`;
+}
diff --git a/App/pelagia-portal/lib/upload-files.ts b/App/pelagia-portal/lib/upload-files.ts
new file mode 100644
index 0000000..2c64ddf
--- /dev/null
+++ b/App/pelagia-portal/lib/upload-files.ts
@@ -0,0 +1,34 @@
+import { linkDocument } from "@/app/actions/link-document";
+
+export async function uploadAndLinkFiles(
+  poId: string,
+  files: File[],
+  type: "po-document" | "receipt" = "po-document"
+): Promise<{ error: string } | null> {
+  for (const file of files) {
+    const signRes = await fetch("/api/files/sign", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ fileName: file.name, mimeType: file.type || "application/octet-stream", poId, type }),
+    });
+    if (!signRes.ok) return { error: `Failed to get upload URL for ${file.name}` };
+    const { uploadUrl, key } = await signRes.json();
+
+    const putRes = await fetch(uploadUrl, {
+      method: "PUT",
+      headers: { "Content-Type": file.type || "application/octet-stream" },
+      body: file,
+    });
+    if (!putRes.ok) return { error: `Failed to upload ${file.name}` };
+
+    const result = await linkDocument({
+      poId,
+      storageKey: key,
+      fileName: file.name,
+      fileSize: file.size,
+      mimeType: file.type || "application/octet-stream",
+    });
+    if ("error" in result) return { error: result.error };
+  }
+  return null;
+}