diff --git a/scripts/test-planner/runtime-profile.mjs b/scripts/test-planner/runtime-profile.mjs
index 79977570f4d..4b33d111e95 100644
--- a/scripts/test-planner/runtime-profile.mjs
+++ b/scripts/test-planner/runtime-profile.mjs
@@ -104,6 +104,7 @@ const LOCAL_MEMORY_BUDGETS = {
     memoryHeavyFileLimit: 8,
     unitFastBatchTargetMs: 10_000,
     channelsBatchTargetMs: 0,
+    extensionsBatchTargetMs: 60_000,
   },
   moderate: {
     vitestCap: 3,
@@ -121,6 +122,7 @@ const LOCAL_MEMORY_BUDGETS = {
     memoryHeavyFileLimit: 12,
     unitFastBatchTargetMs: 15_000,
     channelsBatchTargetMs: 0,
+    extensionsBatchTargetMs: 120_000,
   },
   mid: {
     vitestCap: 4,
@@ -138,6 +140,7 @@ const LOCAL_MEMORY_BUDGETS = {
     memoryHeavyFileLimit: 16,
     unitFastBatchTargetMs: 0,
     channelsBatchTargetMs: 0,
+    extensionsBatchTargetMs: 180_000,
   },
   high: {
     vitestCap: 6,
@@ -155,6 +158,7 @@ const LOCAL_MEMORY_BUDGETS = {
     memoryHeavyFileLimit: 16,
     unitFastBatchTargetMs: 45_000,
     channelsBatchTargetMs: 30_000,
+    extensionsBatchTargetMs: 300_000,
   },
 };
 
@@ -313,7 +317,7 @@ export function resolveExecutionBudget(runtimeCapabilities) {
     unitFastLaneCount: 1,
     unitFastBatchTargetMs: bandBudget.unitFastBatchTargetMs,
     channelsBatchTargetMs: bandBudget.channelsBatchTargetMs ?? 0,
-    extensionsBatchTargetMs: 300_000,
+    extensionsBatchTargetMs: bandBudget.extensionsBatchTargetMs ?? 300_000,
   };
 
   const loadAdjustedBudget = {
diff --git a/test/scripts/test-planner.test.ts b/test/scripts/test-planner.test.ts
index 526b220e06f..99fd6a0f2fa 100644
--- a/test/scripts/test-planner.test.ts
+++ b/test/scripts/test-planner.test.ts
@@ -50,6 +50,38 @@ describe("test planner", () => {
     artifacts.cleanupTempArtifacts();
   });
 
+  it("uses smaller shared extension batches on constrained local hosts", () => {
+    const env = {
+      RUNNER_OS: "macOS",
+      OPENCLAW_TEST_HOST_CPU_COUNT: "8",
+      OPENCLAW_TEST_HOST_MEMORY_GIB: "16",
+      OPENCLAW_TEST_LOAD_AWARE: "0",
+    };
+    const artifacts = createExecutionArtifacts(env);
+    const plan = buildExecutionPlan(
+      {
+        profile: null,
+        mode: "local",
+        surfaces: ["extensions"],
+        passthroughArgs: [],
+      },
+      {
+        env,
+        platform: "darwin",
+        writeTempJsonArtifact: artifacts.writeTempJsonArtifact,
+      },
+    );
+
+    const sharedExtensionBatches = plan.selectedUnits.filter((unit) =>
+      unit.id.startsWith("extensions-batch-"),
+    );
+
+    expect(plan.runtimeCapabilities.memoryBand).toBe("constrained");
+    expect(plan.executionBudget.extensionsBatchTargetMs).toBe(60_000);
+    expect(sharedExtensionBatches.length).toBeGreaterThan(3);
+    artifacts.cleanupTempArtifacts();
+  });
+
   it("scales down mid-tier local concurrency under saturated load", () => {
     const artifacts = createExecutionArtifacts({
       RUNNER_OS: "Linux",