fix(agents): guard extension load error formatting

src/agents/sessions/extensions/loader.test.ts

@@ -86,4 +86,34 @@ export default async function(api) {
     expect(result.extensions).toHaveLength(1);
     expect(Array.from(result.extensions[0]?.tools.keys() ?? [])).toEqual(["healthy_lookup"]);
   });
+
+  it("reports hostile extension factory failures without crashing the loader", async () => {
+    const dir = await mkdtemp(join(tmpdir(), "openclaw-extension-load-error-"));
+    tempDirs.push(dir);
+    const extensionPath = join(dir, "extension.ts");
+    await writeFile(
+      extensionPath,
+      `
+export default async function() {
+  const error = new Error("factory failed");
+  Object.defineProperty(error, "message", {
+    get() {
+      throw new Error("message denied");
+    },
+  });
+  throw error;
+}
+`,
+    );
+
+    const result = await loadExtensions([extensionPath], dir);
+
+    expect(result.extensions).toEqual([]);
+    expect(result.errors).toEqual([
+      {
+        path: extensionPath,
+        error: "Failed to load extension: Unknown extension load error",
+      },
+    ]);
+  });
 });

src/agents/sessions/extensions/loader.ts

@@ -487,6 +487,17 @@ function createExtension(extensionPath: string, resolvedPath: string): Extension
   };
 }
 
+function describeExtensionLoadError(err: unknown): string {
+  try {
+    if (err instanceof Error) {
+      return err.message || err.name || "Unknown extension load error";
+    }
+    return String(err);
+  } catch {
+    return "Unknown extension load error";
+  }
+}
+
 async function loadExtension(
   extensionPath: string,
   cwd: string,
@@ -510,7 +521,7 @@ async function loadExtension(
 
     return { extension, error: null };
   } catch (err) {
-    const message = err instanceof Error ? err.message : String(err);
+    const message = describeExtensionLoadError(err);
     return { extension: null, error: `Failed to load extension: ${message}` };
   }
 }