diff --git a/packages/ai/src/api-registry.test.ts b/packages/ai/src/api-registry.test.ts
index c75180528a68..7fcff82f6b32 100644
--- a/packages/ai/src/api-registry.test.ts
+++ b/packages/ai/src/api-registry.test.ts
@@ -66,8 +66,11 @@ describe("LLM API registry", () => {
   });
 
   it("shares default runtime registrations across duplicated module instances", async () => {
+    // File URLs preserve the cache-busting query through Vitest project shards.
+    // Computed relative imports can escape into unresolved Vite /@fs paths.
     const duplicateRuntime = (await import(
-      ["./internal/default-runtime.js", "duplicate-runtime"].join("?")
+      /* @vite-ignore */ new URL("./internal/default-runtime.ts?duplicate-runtime", import.meta.url)
+        .href
     )) as typeof import("./internal/default-runtime.js");
     const streamSimple = vi.fn(emptyStream);
     duplicateRuntime.registerApiProvider(
diff --git a/test/vitest/vitest.agents-paths.mjs b/test/vitest/vitest.agents-paths.mjs
index fd6c449d355d..e94eb6cf6e8c 100644
--- a/test/vitest/vitest.agents-paths.mjs
+++ b/test/vitest/vitest.agents-paths.mjs
@@ -6,9 +6,11 @@ export const agentsAllTestPatterns = ["src/agents/**/*.test.ts"];
 export const agentsCoreIsolatedTestFiles = [
   "src/agents/image-generation-task-status.test.ts",
   "src/agents/media-generation-task-status-shared.test.ts",
+  "src/agents/mcp-http-fetch.test.ts",
   "src/agents/mcp-transport.test.ts",
   "src/agents/model-auth-env.provider-aliases.test.ts",
   "src/agents/model-selection.plugin-runtime.test.ts",
+  "src/agents/models-config.runtime-source-snapshot.test.ts",
   "src/agents/video-generation-task-status.test.ts",
 ];