fix mcp server cloudfront cache bug

src/mcp-connector/src/mcp.js

@@ -145,7 +145,10 @@ function formatPuterError(err) {
 function jsonResponse(body) {
     return new Response(JSON.stringify(body), {
         status: 200,
-        headers: { 'content-type': 'application/json' },
+        // Per-user MCP results must never be cached by any CDN in front of the
+        // worker. (POST isn't cached by default, but be explicit — a misconfigured
+        // edge cache that ignores method/query could otherwise leak responses.)
+        headers: { 'content-type': 'application/json', 'Cache-Control': 'no-store' },
     });
 }
 
@@ -166,6 +169,7 @@ async function mcpPost(event) {
                 headers: {
                     'content-type': 'application/json',
                     'Access-Control-Allow-Origin': '*',
+                    'Cache-Control': 'no-store',
                     'WWW-Authenticate': `Bearer resource_metadata="${origin}/.well-known/oauth-protected-resource"`,
                 },
             },
@@ -193,9 +197,12 @@ async function mcpPost(event) {
     return jsonResponse(response);
 }
 
-// Discovery / health.
+// Discovery / health. This is the ONLY endpoint safe to cache: it's public,
+// identical for every caller, and hammered by clients polling for the tool list.
+// It's explicitly marked cacheable so a "respect-origin" CDN policy caches this
+// and nothing else (every other response sends no-store).
 function mcpInfo() {
-    return {
+    const body = {
         name: 'puter-mcp',
         description:
             'MCP server for Puter filesystem, static website hosting, serverless worker, and app registration operations. POST JSON-RPC to ' +
@@ -203,6 +210,14 @@ function mcpInfo() {
         transport: 'streamable-http',
         tools: listTools().map((t) => t.name),
     };
+    return new Response(JSON.stringify(body), {
+        status: 200,
+        headers: {
+            'content-type': 'application/json',
+            'Access-Control-Allow-Origin': '*',
+            'Cache-Control': 'public, max-age=300',
+        },
+    });
 }
 
 /** Attach the MCP routes to the (already-initialized) router. */

src/mcp-connector/src/oauth.js

@@ -87,17 +87,27 @@ async function sha256b64url(str) {
 
 // ---- response helpers ------------------------------------------------------
 
+// Every OAuth response is per-request (sealed flow/code blobs, one-time auth
+// codes, tokens) and MUST NOT be cached. Without this, a caching layer in front
+// of the worker (e.g. the puter.com zone) can replay one user's /authorize
+// redirect — and thus their stale callback port / code — to everyone.
+// RFC 6749 §5.1 also mandates no-store on the token endpoint.
+const NO_STORE = {
+    'Cache-Control': 'no-store, no-cache, must-revalidate, max-age=0',
+    Pragma: 'no-cache',
+};
+
 function json(status, obj) {
     return new Response(JSON.stringify(obj), {
         status,
-        headers: { 'content-type': 'application/json', 'Access-Control-Allow-Origin': '*' },
+        headers: { 'content-type': 'application/json', 'Access-Control-Allow-Origin': '*', ...NO_STORE },
     });
 }
 
 function redirect(location) {
     return new Response(null, {
         status: 302,
-        headers: { Location: location, 'Access-Control-Allow-Origin': '*' },
+        headers: { Location: location, 'Access-Control-Allow-Origin': '*', ...NO_STORE },
     });
 }