fix(apps): guide generic MCP connection failures

Map OAuth origin, duplicate-name, and DNS failures to stable operator guidance, and derive collision-resistant defaults from host, port, and path.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/remote-http-fetch.ts

@@ -32,6 +32,7 @@ const DEFAULT_CONNECT_TIMEOUT_MS = 10_000;
  * pass `responseTimeoutMs` so this default never truncates it.
  */
 const DEFAULT_RESPONSE_TIMEOUT_MS = 30_000;
+const DNS_RESOLUTION_ERROR_CODES = new Set(["ENODATA", "ENOTFOUND", "EAI_AGAIN"]);
 
 /** How a verified socket is opened. Overridable so tests can simulate a rebind. */
 export type RemoteHttpSocketFactory = (target: {
@@ -103,11 +104,34 @@ export async function guardedRemoteHttpFetch(
   const literalHost = isIP(endpoint.hostname.replace(/^\[|\]$/g, "")) !== 0;
   const platformFetch = options.unpinnedFetch ?? fetch;
   if (approved.length === 0 || literalHost) {
-    return platformFetch(endpoint.toString(), { ...init, redirect: "manual" });
+    try {
+      return await platformFetch(endpoint.toString(), { ...init, redirect: "manual" });
+    } catch (error) {
+      if (isDnsResolutionError(error)) {
+        throw options.error(
+          "Remote MCP connection hostname could not be resolved",
+          "remote_http_dns_failed",
+        );
+      }
+      throw error;
+    }
   }
   return pinnedRequest(endpoint, approved, init, options);
 }
 
+/** Node's platform fetch wraps DNS failures in TypeError.cause. */
+function isDnsResolutionError(error: unknown): boolean {
+  const seen = new Set<unknown>();
+  let current = error;
+  while (typeof current === "object" && current !== null && !seen.has(current)) {
+    seen.add(current);
+    const record = current as { code?: unknown; cause?: unknown };
+    if (typeof record.code === "string" && DNS_RESOLUTION_ERROR_CODES.has(record.code)) return true;
+    current = record.cause;
+  }
+  return false;
+}
+
 async function pinnedRequest(
   endpoint: URL,
   approved: string[],

server/src/services/tool-access.ts

@@ -1655,6 +1655,9 @@ function healthFailureHttpStatus(failure: { status: ToolConnectionHealthStatus;
 function sanitizeHttpFailure(error: unknown): { status: ToolConnectionHealthStatus; message: string; code: string } {
   if (error instanceof HttpError) {
     const code = asRecord(error.details).code;
+    if (typeof code === "string" && code.startsWith("remote_http_")) {
+      return { status: "error", message: error.message, code };
+    }
     if (isOAuthEndpointRejection(error)) {
       return { status: "error", message: error.message, code: String(code) };
     }
@@ -4120,7 +4123,9 @@ export function toolAccessService(db: Db, options: ToolAccessServiceOptions = {}
   function defaultLinkName(link: string): string {
     try {
       const url = new URL(link);
-      return url.hostname.replace(/^www\./, "") || "MCP app";
+      const host = url.host.replace(/^www\./, "");
+      const path = url.pathname === "/" ? "" : url.pathname.replace(/\/+$/, "");
+      return `${host}${path}`.slice(0, 160) || "MCP app";
     } catch {
       return "MCP app";
     }
@@ -7285,7 +7290,11 @@ export function toolAccessService(db: Db, options: ToolAccessServiceOptions = {}
             ),
           )
           .limit(1);
-        if (duplicate) throw conflict("A tool access record with that name already exists");
+        if (duplicate) {
+          throw conflict("A tool access record with that name already exists", {
+            code: "tool_access_name_conflict",
+          });
+        }
       }
       const [row] = await db
         .update(toolApplications)
@@ -8863,7 +8872,9 @@ export function toolAccessService(db: Db, options: ToolAccessServiceOptions = {}
         constraint?.includes("tool_applications") ||
         /duplicate key value|unique constraint|tool_applications_company_id_name_unique/i.test(message)
       ) {
-        throw conflict("A tool access record with that name already exists");
+        throw conflict("A tool access record with that name already exists", {
+          code: "tool_access_name_conflict",
+        });
       }
       throw error;
     },