diff --git a/src/app/api/circles/[id]/posts/upload/route.ts b/src/app/api/circles/[id]/posts/upload/route.ts
new file mode 100644
index 0000000..45439f2
--- /dev/null
+++ b/src/app/api/circles/[id]/posts/upload/route.ts
@@ -0,0 +1,83 @@
+import { NextResponse } from "next/server";
+import { sql } from "@/db";
+import { requireFamily } from "@/lib/auth";
+import { S3Client, PutObjectCommand } from "@aws-sdk/client-s3";
+
+const R2_PUBLIC_URL = process.env.R2_PUBLIC_URL ?? "";
+const MAX_BYTES     = 20 * 1024 * 1024; // 20 MB
+
+const ALLOWED: Record<string, string> = {
+  "image/jpeg": "jpg", "image/jpg": "jpg", "image/png": "png",
+  "image/webp": "webp", "image/heic": "heic", "image/heif": "heif",
+  "image/gif": "gif",
+};
+
+function makeR2Client() {
+  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!,
+    },
+  });
+}
+
+// POST — server-side image upload for circle posts (avoids CORS on direct R2 PUT)
+export async function POST(
+  req: Request,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  try {
+    const auth = await requireFamily();
+    if (!auth.success) return NextResponse.json({ error: auth.error }, { status: auth.status });
+
+    const familyId = auth.session!.familyId!;
+    const { id: circleId } = await params;
+
+    // Must be a circle member
+    const rows = await sql.unsafe(
+      `SELECT role FROM circle_members WHERE circle_id = $1 AND family_id = $2`,
+      [circleId, familyId]
+    );
+    if (!rows[0]) return NextResponse.json({ error: "Not a circle member" }, { status: 403 });
+
+    const formData = await req.formData();
+    const file = formData.get("file") as File | null;
+    if (!file) return NextResponse.json({ error: "No file provided" }, { status: 400 });
+
+    if (file.size > MAX_BYTES) {
+      return NextResponse.json({ error: "File too large (max 20 MB)" }, { status: 400 });
+    }
+
+    // Normalise content type — browsers sometimes send empty type for HEIC/camera photos
+    let contentType = file.type || "";
+    if (!contentType || !ALLOWED[contentType]) {
+      const ext = file.name.split(".").pop()?.toLowerCase() ?? "";
+      const EXT_MAP: Record<string, string> = {
+        jpg: "image/jpeg", jpeg: "image/jpeg", png: "image/png",
+        webp: "image/webp", heic: "image/heic", heif: "image/heif", gif: "image/gif",
+      };
+      contentType = EXT_MAP[ext] ?? contentType;
+    }
+    if (!ALLOWED[contentType]) {
+      return NextResponse.json({ error: `Unsupported file type: ${contentType || file.name}` }, { status: 400 });
+    }
+
+    const ext    = ALLOWED[contentType];
+    const tmpKey = `circle-posts/tmp/${familyId}/${Date.now()}.${ext}`;
+
+    const buffer = Buffer.from(await file.arrayBuffer());
+    await makeR2Client().send(new PutObjectCommand({
+      Bucket:      process.env.R2_BUCKET_NAME!,
+      Key:         tmpKey,
+      Body:        buffer,
+      ContentType: contentType,
+    }));
+
+    return NextResponse.json({ tmpKey, publicUrl: `${R2_PUBLIC_URL}/${tmpKey}` });
+  } catch (err: unknown) {
+    const msg = err instanceof Error ? err.message : String(err);
+    return NextResponse.json({ error: msg }, { status: 500 });
+  }
+}
diff --git a/src/app/circle/[id]/page.tsx b/src/app/circle/[id]/page.tsx
index 736dd55..3901208 100644
--- a/src/app/circle/[id]/page.tsx
+++ b/src/app/circle/[id]/page.tsx
@@ -228,30 +228,20 @@ function CreatePostModal({
       let tmpKey: string | null = null;
 
       if (imageFile) {
-        // Get presigned URL — pass both type and name so server can normalise empty types
-        const presignRes = await fetch(`/api/circles/${circleId}/posts`, {
-          method:  "POST",
-          headers: { "Content-Type": "application/json" },
-          body:    JSON.stringify({ action: "presign", contentType: imageFile.type, filename: imageFile.name }),
-        });
-        const presignData = await presignRes.json();
-        if (!presignRes.ok || !presignData.uploadUrl) {
-          setPostError(presignData.error ?? "Could not prepare image upload");
-          setPosting(false);
-          return;
-        }
-        // Upload directly to R2 using the normalised content type from server
-        const uploadRes = await fetch(presignData.uploadUrl, {
-          method:  "PUT",
-          body:    imageFile,
-          headers: { "Content-Type": presignData.contentType ?? imageFile.type },
+        // Upload via server (avoids CORS issues with direct R2 PUT)
+        const fd = new FormData();
+        fd.append("file", imageFile);
+        const uploadRes  = await fetch(`/api/circles/${circleId}/posts/upload`, {
+          method: "POST",
+          body:   fd,
         });
+        const uploadData = await uploadRes.json();
         if (!uploadRes.ok) {
-          setPostError("Image upload failed — please try again");
+          setPostError(uploadData.error ?? "Image upload failed");
           setPosting(false);
           return;
         }
-        tmpKey = presignData.tmpKey;
+        tmpKey = uploadData.tmpKey;
       }
 
       const postRes  = await fetch(`/api/circles/${circleId}/posts`, {