From 55f95283e3f0d7c835e00e16aa065db565d5c034 Mon Sep 17 00:00:00 2001
From: ribdsp <113304041+ribdsp@users.noreply.github.com>
Date: Fri, 28 Aug 2026 21:02:28 +0700
Subject: [PATCH] fix(webmcp): send Origin-Agent-Cluster so tools can register
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The document has to be origin-isolated before WebMCP will accept a tool, and
that is a separate requirement from the origin trial. Production had only
`Origin-Trial`, which produced the worst failure available: `document
.modelContext` existed, so the banner reported `native` in green, while all
sixteen `registerTool` calls threw and `registerTools` returned an empty
array. Live URL, green status line, `0 tools`, nothing agent-callable.

The header now ships whether or not a token is configured, since isolation
is not part of the trial — `headers()` no longer has a path that returns
nothing.
---
 traces/next.config.mjs | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/traces/next.config.mjs b/traces/next.config.mjs
index 54d4f04..f7c94ad 100644
--- a/traces/next.config.mjs
+++ b/traces/next.config.mjs
@@ -10,8 +10,8 @@ import { fileURLToPath } from 'node:url'
  * about an hour before you find it.
  *
  * The token is bound to an origin, so localhost and production need different ones. Put yours in
- * `.env.local` (see `.env.example`). With no token set, no header is sent and the polyfill in
- * `src/lib/webmcp/polyfill.ts` takes over.
+ * `.env.local` (see `.env.example`). With no token set, no *trial* header is sent and the polyfill in
+ * `src/lib/webmcp/polyfill.ts` takes over — `Origin-Agent-Cluster` ships either way, see `headers()`.
  *
  * **Do not add `output: 'export'`.** Every page here is prerendered anyway — `next build` reports `/` as
  * `○ (Static)` — so a static export looks like a free simplification, and it is the one change that
@@ -34,13 +34,23 @@ const nextConfig = {
   outputFileTracingRoot: fileURLToPath(new URL('.', import.meta.url)),
 
   async headers() {
+    /*
+     * Origin isolation is not optional, and it is not part of the trial: WebMCP refuses to register a
+     * tool unless the document is origin-isolated, so this header ships whether or not a token is
+     * configured. Sending only `Origin-Trial` produces the worst available failure — `document
+     * .modelContext` exists, so the banner reports `native` in green, while all sixteen
+     * `registerTool` calls throw and `registerTools` returns an empty array. The page looks healthy
+     * and nothing on it is agent-callable.
+     *
+     * `?0` is not a weaker version of this, it is the opposite: it opts the document out.
+     */
+    const isolation = { key: 'Origin-Agent-Cluster', value: '?1' }
     const token = process.env.NEXT_PUBLIC_WEBMCP_ORIGIN_TRIAL_TOKEN
-    if (!token) return []
 
     return [
       {
         source: '/:path*',
-        headers: [{ key: 'Origin-Trial', value: token }],
+        headers: token ? [isolation, { key: 'Origin-Trial', value: token }] : [isolation],
       },
     ]
   },