diff --git a/scripts/test-projects.mjs b/scripts/test-projects.mjs
index c76d07e55bd..e818d2d4f31 100644
--- a/scripts/test-projects.mjs
+++ b/scripts/test-projects.mjs
@@ -7,6 +7,7 @@ import {
   createVitestRunSpecs,
   parseTestProjectsArgs,
   resolveChangedTargetArgs,
+  shouldUseLocalFullSuiteParallelByDefault,
   writeVitestIncludeFile,
 } from "./test-projects.test-support.mjs";
 import {
@@ -125,10 +126,15 @@ function resolveParallelFullSuiteConcurrency(specCount, env) {
   if (override !== null) {
     return Math.min(override, specCount);
   }
+  if (env.OPENCLAW_TEST_PROJECTS_SERIAL === "1") {
+    return 1;
+  }
+  if (env.CI === "true" || env.GITHUB_ACTIONS === "true") {
+    return 1;
+  }
   if (
-    env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS !== "1" ||
-    env.CI === "true" ||
-    env.GITHUB_ACTIONS === "true"
+    env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS !== "1" &&
+    !shouldUseLocalFullSuiteParallelByDefault(env)
   ) {
     return 1;
   }
diff --git a/scripts/test-projects.test-support.mjs b/scripts/test-projects.test-support.mjs
index 85b55c0206d..1392327ebbb 100644
--- a/scripts/test-projects.test-support.mjs
+++ b/scripts/test-projects.test-support.mjs
@@ -623,7 +623,8 @@ export function buildFullSuiteVitestRunPlans(args, cwd = process.cwd()) {
   const parallelShardCount = Number.parseInt(process.env.OPENCLAW_TEST_PROJECTS_PARALLEL ?? "", 10);
   const expandToProjectConfigs =
     process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS === "1" ||
-    (Number.isFinite(parallelShardCount) && parallelShardCount > 1);
+    (Number.isFinite(parallelShardCount) && parallelShardCount > 1) ||
+    shouldUseLocalFullSuiteParallelByDefault(process.env);
   return fullSuiteVitestShards.flatMap((shard) => {
     if (
       process.env.OPENCLAW_TEST_SKIP_FULL_EXTENSIONS_SHARD === "1" &&
@@ -642,6 +643,12 @@ export function buildFullSuiteVitestRunPlans(args, cwd = process.cwd()) {
   });
 }
 
+export function shouldUseLocalFullSuiteParallelByDefault(env = process.env) {
+  return (
+    env.OPENCLAW_TEST_PROJECTS_SERIAL !== "1" && env.CI !== "true" && env.GITHUB_ACTIONS !== "true"
+  );
+}
+
 export function createVitestRunSpecs(args, params = {}) {
   const cwd = params.cwd ?? process.cwd();
   const plans = buildVitestRunPlans(args, cwd);
diff --git a/test/scripts/test-projects.test.ts b/test/scripts/test-projects.test.ts
index 6ada3dc0d51..da3f61d30fb 100644
--- a/test/scripts/test-projects.test.ts
+++ b/test/scripts/test-projects.test.ts
@@ -196,9 +196,11 @@ describe("scripts/test-projects changed-target routing", () => {
 describe("scripts/test-projects full-suite sharding", () => {
   it("splits untargeted runs into fixed core shards and per-extension configs", () => {
     const previousParallel = process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    const previousSerial = process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
     delete process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
     delete process.env.OPENCLAW_TEST_SKIP_FULL_EXTENSIONS_SHARD;
     delete process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    process.env.OPENCLAW_TEST_PROJECTS_SERIAL = "1";
     try {
       expect(buildFullSuiteVitestRunPlans([], process.cwd()).map((plan) => plan.config)).toEqual([
         "vitest.full-core-unit-fast.config.ts",
@@ -239,13 +241,67 @@ describe("scripts/test-projects full-suite sharding", () => {
       } else {
         process.env.OPENCLAW_TEST_PROJECTS_PARALLEL = previousParallel;
       }
+      if (previousSerial === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_SERIAL = previousSerial;
+      }
+    }
+  });
+
+  it("expands untargeted local runs to leaf project configs by default", () => {
+    const previousLeafShards = process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
+    const previousParallel = process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    const previousSerial = process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
+    const previousCi = process.env.CI;
+    const previousActions = process.env.GITHUB_ACTIONS;
+    delete process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
+    delete process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    delete process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
+    delete process.env.CI;
+    delete process.env.GITHUB_ACTIONS;
+    try {
+      const configs = buildFullSuiteVitestRunPlans([], process.cwd()).map((plan) => plan.config);
+
+      expect(configs).toContain("vitest.gateway.config.ts");
+      expect(configs).toContain("vitest.extension-telegram.config.ts");
+      expect(configs).not.toContain("vitest.full-agentic.config.ts");
+      expect(configs).not.toContain("vitest.full-core-unit-fast.config.ts");
+    } finally {
+      if (previousLeafShards === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_LEAF_SHARDS = previousLeafShards;
+      }
+      if (previousParallel === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_PARALLEL = previousParallel;
+      }
+      if (previousSerial === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_SERIAL = previousSerial;
+      }
+      if (previousCi === undefined) {
+        delete process.env.CI;
+      } else {
+        process.env.CI = previousCi;
+      }
+      if (previousActions === undefined) {
+        delete process.env.GITHUB_ACTIONS;
+      } else {
+        process.env.GITHUB_ACTIONS = previousActions;
+      }
     }
   });
 
   it("can skip the aggregate extension shard when CI runs dedicated extension shards", () => {
     const previous = process.env.OPENCLAW_TEST_SKIP_FULL_EXTENSIONS_SHARD;
     const previousParallel = process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    const previousSerial = process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
     delete process.env.OPENCLAW_TEST_PROJECTS_PARALLEL;
+    process.env.OPENCLAW_TEST_PROJECTS_SERIAL = "1";
     process.env.OPENCLAW_TEST_SKIP_FULL_EXTENSIONS_SHARD = "1";
     try {
       const configs = buildFullSuiteVitestRunPlans([], process.cwd()).map((plan) => plan.config);
@@ -263,6 +319,11 @@ describe("scripts/test-projects full-suite sharding", () => {
       } else {
         process.env.OPENCLAW_TEST_PROJECTS_PARALLEL = previousParallel;
       }
+      if (previousSerial === undefined) {
+        delete process.env.OPENCLAW_TEST_PROJECTS_SERIAL;
+      } else {
+        process.env.OPENCLAW_TEST_PROJECTS_SERIAL = previousSerial;
+      }
     }
   });