diff --git a/scripts/lib/ci-changed-node-test-plan.mts b/scripts/lib/ci-changed-node-test-plan.mts
index 8b21a762731e..2e7b0e449bec 100644
--- a/scripts/lib/ci-changed-node-test-plan.mts
+++ b/scripts/lib/ci-changed-node-test-plan.mts
@@ -353,6 +353,15 @@ function createChangedExtensionConfigShards(extensionRoots: string[]) {
   });
 }
 
+function createChangedExtensionConfigShardsForPaths(changedPaths: string[], cwd: string) {
+  const relevantPaths = changedPaths.filter(
+    (changedPath) =>
+      changedPath.startsWith("extensions/") &&
+      (existsSync(path.join(cwd, changedPath)) || !isTestFileTarget(changedPath)),
+  );
+  return createChangedExtensionConfigShards(resolveChangedExtensionRoots(relevantPaths));
+}
+
 /**
  * The fail-safe cause leaves the non-extension diff's extension impact unbounded,
  * so whole extension configs are required; precise targets would under-cover.
@@ -362,19 +371,7 @@ export function createChangedExtensionFallbackShards(
   options: CwdOptions = {},
 ): ChangedNodeTestShard[] {
   const cwd = options.cwd ?? process.cwd();
-  const extensionPaths = changedPaths.filter((changedPath) =>
-    changedPath.startsWith("extensions/"),
-  );
-  if (extensionPaths.length === 0) {
-    return [];
-  }
-  const relevantPaths = extensionPaths.filter(
-    (changedPath) => existsSync(path.join(cwd, changedPath)) || !isTestFileTarget(changedPath),
-  );
-  if (relevantPaths.length === 0) {
-    return [];
-  }
-  return createChangedExtensionConfigShards(resolveChangedExtensionRoots(relevantPaths));
+  return createChangedExtensionConfigShardsForPaths(changedPaths, cwd);
 }
 
 /**
@@ -404,9 +401,13 @@ export function createChangedNodeTestShards(
   }
 
   const policyTargetsByPath = new Map(
-    livePaths.map((changedPath) => [changedPath, resolvePolicyTestTargets([changedPath])]),
+    livePaths
+      .filter((changedPath) => !changedPath.startsWith("extensions/"))
+      .map((changedPath) => [changedPath, resolvePolicyTestTargets([changedPath])]),
+  );
+  const regularLivePaths = livePaths.filter(
+    (changedPath) => !changedPath.startsWith("extensions/") && !isPolicyTestOwnedPath(changedPath),
   );
-  const regularLivePaths = livePaths.filter((changedPath) => !isPolicyTestOwnedPath(changedPath));
 
   // Workspace package consumers often use package specifiers, which the
   // relative import graph cannot connect back to the changed package source.
@@ -436,6 +437,7 @@ export function createChangedNodeTestShards(
   // Boundary-config targets run as regular nondist targets: the boundary
   // suite scans the checked-out tree and never consumes the built dist.
   const shards = [
+    ...createChangedExtensionConfigShardsForPaths(livePaths, cwd),
     ...createChangedTargetShards(targets, {
       checkName: "checks-node-changed",
       shardName: "changed",
diff --git a/test/scripts/ci-changed-node-test-plan.test.ts b/test/scripts/ci-changed-node-test-plan.test.ts
index 5256ea3e8b48..d479981a7982 100644
--- a/test/scripts/ci-changed-node-test-plan.test.ts
+++ b/test/scripts/ci-changed-node-test-plan.test.ts
@@ -283,6 +283,22 @@ describe("CI changed Node test plan", () => {
     ]);
   });
 
+  it.each([
+    {
+      changedPath: "extensions/browser/src/browser/cdp.helpers.test.ts",
+      config: "test/vitest/vitest.extension-browser.config.ts",
+    },
+    {
+      changedPath: "extensions/codex/src/session-upstream-marker.ts",
+      config: "test/vitest/vitest.extension-codex.config.ts",
+    },
+  ])("runs the whole owning extension config for $changedPath", ({ changedPath, config }) => {
+    const shards = createChangedNodeTestShards([changedPath]);
+
+    expect(shards).not.toBeNull();
+    expect(shards?.flatMap((shard) => shard.configs)).toContain(config);
+  });
+
   it("preserves Matrix process bounds in mixed package fallbacks", () => {
     const shards = createChangedExtensionFallbackShards([
       "packages/gateway-protocol/src/frame-guards.ts",
@@ -406,20 +422,19 @@ describe("CI changed Node test plan", () => {
     expect(new Set(targets).size).toBe(targets.length);
   });
 
-  it("serializes changed-test chunks that contain Memory Core integration tests", () => {
+  it("serializes the owning Memory Core extension config for direct changes", () => {
     const shards = createChangedNodeTestShards([
       "extensions/memory-core/src/memory/mmr.ts",
       "extensions/memory-core/src/memory/mmr.test.ts",
     ]);
     expect(shards).not.toBeNull();
-    const targetShards = shards?.filter((shard) => shard.targets) ?? [];
-    expect(targetShards.length).toBeGreaterThan(0);
-    expect(
-      targetShards
-        .filter((shard) =>
-          shard.targets?.some((target) => target.startsWith("extensions/memory-core/")),
-        )
-        .every((shard) => shard.planConcurrency === 1),
-    ).toBe(true);
+    expect(shards).toContainEqual({
+      checkName: "checks-node-changed-extensions-config",
+      configs: ["test/vitest/vitest.extension-memory.config.ts"],
+      planConcurrency: 1,
+      requiresDist: false,
+      runner: "blacksmith-8vcpu-ubuntu-2404",
+      shardName: "changed-extensions-config",
+    });
   });
 });