diff --git a/scripts/test-projects.test-support.mjs b/scripts/test-projects.test-support.mjs
index d7ec3f854d2..c82fd4ed2dd 100644
--- a/scripts/test-projects.test-support.mjs
+++ b/scripts/test-projects.test-support.mjs
@@ -644,6 +644,9 @@ export function buildFullSuiteVitestRunPlans(args, cwd = process.cwd()) {
 }
 
 export function shouldUseLocalFullSuiteParallelByDefault(env = process.env) {
+  if (hasConservativeVitestWorkerBudget(env)) {
+    return false;
+  }
   return (
     env.OPENCLAW_TEST_PROJECTS_SERIAL !== "1" && env.CI !== "true" && env.GITHUB_ACTIONS !== "true"
   );
@@ -654,6 +657,13 @@ function parsePositiveInt(value) {
   return Number.isFinite(parsed) && parsed > 0 ? parsed : null;
 }
 
+function hasConservativeVitestWorkerBudget(env) {
+  const workerBudget = parsePositiveInt(
+    env.OPENCLAW_VITEST_MAX_WORKERS ?? env.OPENCLAW_TEST_WORKERS,
+  );
+  return workerBudget !== null && workerBudget <= 1;
+}
+
 export function resolveParallelFullSuiteConcurrency(specCount, env = process.env) {
   const override = parsePositiveInt(env.OPENCLAW_TEST_PROJECTS_PARALLEL);
   if (override !== null) {
@@ -665,10 +675,7 @@ export function resolveParallelFullSuiteConcurrency(specCount, env = process.env
   if (env.CI === "true" || env.GITHUB_ACTIONS === "true") {
     return 1;
   }
-  const workerBudget = parsePositiveInt(
-    env.OPENCLAW_VITEST_MAX_WORKERS ?? env.OPENCLAW_TEST_WORKERS,
-  );
-  if (workerBudget !== null && workerBudget <= 1) {
+  if (hasConservativeVitestWorkerBudget(env)) {
     return 1;
   }
   if (
diff --git a/src/scripts/test-projects.test.ts b/src/scripts/test-projects.test.ts
index 99253f0f568..885432f975b 100644
--- a/src/scripts/test-projects.test.ts
+++ b/src/scripts/test-projects.test.ts
@@ -1,12 +1,22 @@
 import { describe, expect, it } from "vitest";
 
 const {
+  buildFullSuiteVitestRunPlans,
   buildVitestArgs,
   buildVitestRunPlans,
   createVitestRunSpecs,
   parseTestProjectsArgs,
   resolveParallelFullSuiteConcurrency,
 } = (await import("../../scripts/test-projects.test-support.mjs")) as unknown as {
+  buildFullSuiteVitestRunPlans: (
+    args: string[],
+    cwd?: string,
+  ) => Array<{
+    config: string;
+    forwardedArgs: string[];
+    includePatterns: string[] | null;
+    watchMode: boolean;
+  }>;
   buildVitestArgs: (args: string[], cwd?: string) => string[];
   buildVitestRunPlans: (
     args: string[],
@@ -411,6 +421,45 @@ describe("test-projects args", () => {
     ).toBe(1);
   });
 
+  it("keeps conservative full-suite runs on aggregate shards", () => {
+    const originalVitestMaxWorkers = process.env.OPENCLAW_VITEST_MAX_WORKERS;
+    const originalTestWorkers = process.env.OPENCLAW_TEST_WORKERS;
+    const originalProjectParallel = process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    const originalLeafShards = process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
+    try {
+      process.env.OPENCLAW_VITEST_MAX_WORKERS = "1";
+      delete process.env.OPENCLAW_TEST_WORKERS;
+      delete process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+      delete process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
+
+      const configs = buildFullSuiteVitestRunPlans([]).map((plan) => plan.config);
+
+      expect(configs).toContain("vitest.full-agentic.config.ts");
+      expect(configs).not.toContain("vitest.plugins.config.ts");
+    } finally {
+      if (originalVitestMaxWorkers === undefined) {
+        delete process.env.OPENCLAW_VITEST_MAX_WORKERS;
+      } else {
+        process.env.OPENCLAW_VITEST_MAX_WORKERS = originalVitestMaxWorkers;
+      }
+      if (originalTestWorkers === undefined) {
+        delete process.env.OPENCLAW_TEST_WORKERS;
+      } else {
+        process.env.OPENCLAW_TEST_WORKERS = originalTestWorkers;
+      }
+      if (originalProjectParallel === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_PARALLEL = originalProjectParallel;
+      }
+      if (originalLeafShards === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS = originalLeafShards;
+      }
+    }
+  });
+
   it("keeps explicit project-level parallelism authoritative", () => {
     expect(
       resolveParallelFullSuiteConcurrency(58, {