From f9560e5bac403a4dc09bc6f0d5e0195d495257d3 Mon Sep 17 00:00:00 2001
From: xujiantop-crypto <265865031+xujiantop-crypto@users.noreply.github.com>
Date: Sun, 6 Sep 2026 17:21:06 +0800
Subject: [PATCH] fix(installer): report the requested unsupported platform

---
 mcp-package/bin/fetch-engine.js       |  5 +++--
 mcp-package/test/fetch-engine.test.js | 28 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/mcp-package/bin/fetch-engine.js b/mcp-package/bin/fetch-engine.js
index d8ba0f1..4290181 100644
--- a/mcp-package/bin/fetch-engine.js
+++ b/mcp-package/bin/fetch-engine.js
@@ -387,9 +387,10 @@ function isStale(targetDir, version) {
  *   and which assets were downloaded (empty when everything was already there).
  */
 async function ensureEngine(version, targetDir, options = {}) {
-  const assets = requiredAssets(options.platform, options.arch);
+  const { platform = os.platform(), arch = os.arch() } = options;
+  const assets = requiredAssets(platform, arch);
   if (assets.length === 0) {
-    throw new Error(`no CodeGraph engine is published for ${os.platform()}-${os.arch()}`);
+    throw new Error(`no CodeGraph engine is published for ${platform}-${arch}`);
   }
 
   fs.mkdirSync(targetDir, { recursive: true });
diff --git a/mcp-package/test/fetch-engine.test.js b/mcp-package/test/fetch-engine.test.js
index f1cfe91..9d7f881 100644
--- a/mcp-package/test/fetch-engine.test.js
+++ b/mcp-package/test/fetch-engine.test.js
@@ -474,6 +474,34 @@ async function run() {
   // someone else's binary.
   check(platformBinaryName("linux", "riscv64") === null, "an unbuilt arch resolves to nothing");
   check(requiredAssets("linux", "riscv64").length === 0, "an unpublished pair needs no assets");
+
+  // --- unsupported installs report the requested platform and arch -----
+  {
+    const dir = scratch();
+    const targetDir = path.join(dir, "engine");
+    const { server, baseUrl } = await startRelease({});
+    try {
+      for (const [options, target] of [
+        [{ platform: "freebsd", arch: "x64" }, "freebsd-x64"],
+        [{ platform: "linux", arch: "riscv64" }, "linux-riscv64"],
+        [{ platform: "win32", arch: "arm" }, "win32-arm"],
+        [{ platform: "freebsd" }, `freebsd-${os.arch()}`],
+        [{ arch: "riscv64" }, `${os.platform()}-riscv64`],
+      ]) {
+        let threw = null;
+        await ensureEngine(VERSION, targetDir, { ...options, baseUrl }).catch((e) => (threw = e));
+        check(
+          threw !== null && threw.message === `no CodeGraph engine is published for ${target}`,
+          `an unsupported install reports ${target}`
+        );
+        check(!fs.existsSync(targetDir), `${target} is rejected before creating the install directory`);
+      }
+    } finally {
+      server.close();
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  }
+
   // Every name the mapping can return has to be a name the release publishes,
   // or an install fetches a 404.
   for (const [p, a] of [