fix(test): allow empty extension lane

vitest.extensions.config.ts

@@ -25,6 +25,7 @@ export default createScopedVitestConfig(
   {
     dir: "extensions",
     pool: "threads",
+    passWithNoTests: true,
     // Channel implementations live under extensions/ but are tested by
     // vitest.channels.config.ts (pnpm test:channels) which provides
     // the heavier mock scaffolding they need.

vitest.scoped-config.ts

@@ -13,12 +13,25 @@ export function resolveVitestIsolation(
 
 export function createScopedVitestConfig(
   include: string[],
-  options?: { dir?: string; exclude?: string[]; pool?: "threads" | "forks" },
+  options?: {
+    dir?: string;
+    exclude?: string[];
+    pool?: "threads" | "forks";
+    passWithNoTests?: boolean;
+  },
 ) {
   const base = baseConfig as unknown as Record<string, unknown>;
   const baseTest =
-    (baseConfig as { test?: { dir?: string; exclude?: string[]; pool?: "threads" | "forks" } })
+    (
-      .test ?? {};
+      baseConfig as {
+        test?: {
+          dir?: string;
+          exclude?: string[];
+          pool?: "threads" | "forks";
+          passWithNoTests?: boolean;
+        };
+      }
+    ).test ?? {};
   const exclude = [...(baseTest.exclude ?? []), ...(options?.exclude ?? [])];
 
   return defineConfig({
@@ -30,6 +43,9 @@ export function createScopedVitestConfig(
       include,
       exclude,
       ...(options?.pool ? { pool: options.pool } : {}),
+      ...(options?.passWithNoTests !== undefined
+        ? { passWithNoTests: options.passWithNoTests }
+        : {}),
     },
   });
 }