diff --git a/CHANGELOG.md b/CHANGELOG.md
index 43118dee25d..87bdb001a2a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Plugin SDK/testing: lazy-load TypeScript from the plugin test-contract runtime and add release checks for critical SDK contract entrypoint imports and bundle size, so published packages fail preflight before shipping ESM-incompatible or oversized contract helpers. Thanks @vincentkoc.
 - CLI/browser: preserve parent flags while lazy-loading browser subcommands, so `openclaw browser --json open` and `openclaw browser --json tabs` keep machine-readable output after reparsing. Fixes #74574. Thanks @devintegeritsm.
 - Plugins/runtime-deps: add `openclaw plugins deps` inspection and repair with script-free package-manager defaults shared across plugin installers, so operators can repair missing bundled runtime deps without corrupting JSON output or blocking unrelated conflict-free deps. Thanks @vincentkoc.
 - Agents/output: strip internal `[tool calls omitted]` replay placeholders from user-facing replies while preserving visible reply whitespace. Fixes #74573. Thanks @blaspat.
diff --git a/scripts/release-check.ts b/scripts/release-check.ts
index 764bdf1e978..98faae157c7 100755
--- a/scripts/release-check.ts
+++ b/scripts/release-check.ts
@@ -3,6 +3,7 @@
 import { execFileSync, execSync } from "node:child_process";
 import {
   existsSync,
+  lstatSync,
   mkdtempSync,
   mkdirSync,
   realpathSync,
@@ -116,6 +117,15 @@ const appcastPath = resolve("appcast.xml");
 const laneBuildMin = 1_000_000_000;
 const laneFloorAdoptionDateKey = 20260227;
 const SAFE_UNIX_SMOKE_PATH = "/usr/bin:/bin";
+export const MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES = 2 * 1024 * 1024;
+export const CRITICAL_PLUGIN_SDK_SIZE_CHECK_SPECIFIERS = [
+  "openclaw/plugin-sdk/agent-runtime-test-contracts",
+  "openclaw/plugin-sdk/plugin-test-contracts",
+  "openclaw/plugin-sdk/provider-test-contracts",
+] as const;
+export const CRITICAL_PLUGIN_SDK_IMPORT_SMOKE_SPECIFIERS = [
+  "openclaw/plugin-sdk/plugin-test-contracts",
+] as const;
 export const PACKED_CLI_SMOKE_COMMANDS = [
   ["--help"],
   ["onboard", "--help"],
@@ -843,6 +853,44 @@ async function checkPluginSdkExports() {
   }
 }
 
+export function collectCriticalPluginSdkEntrypointSizeErrors(rootDir = process.cwd()): string[] {
+  const errors: string[] = [];
+  for (const specifier of CRITICAL_PLUGIN_SDK_SIZE_CHECK_SPECIFIERS) {
+    const subpath = specifier.slice("openclaw/plugin-sdk/".length);
+    const relativePath = `dist/plugin-sdk/${subpath}.js`;
+    const filePath = resolve(rootDir, relativePath);
+    if (!existsSync(filePath)) {
+      errors.push(`${relativePath} is missing.`);
+      continue;
+    }
+    const stat = lstatSync(filePath);
+    if (!stat.isFile()) {
+      errors.push(`${relativePath} is not a file.`);
+      continue;
+    }
+    if (stat.size > MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES) {
+      errors.push(
+        `${relativePath} is ${stat.size} bytes, exceeding ${MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES} bytes. Keep public SDK test-contract entrypoints lazy and avoid bundling compiler/runtime internals.`,
+      );
+    }
+  }
+  return errors;
+}
+
+function runCriticalPluginSdkEntrypointImportSmoke() {
+  const script = [
+    `const specifiers = ${JSON.stringify(CRITICAL_PLUGIN_SDK_IMPORT_SMOKE_SPECIFIERS)};`,
+    `const importModule = new Function("specifier", "return imp" + "ort(specifier)");`,
+    "for (const specifier of specifiers) {",
+    "  await importModule(specifier);",
+    "}",
+  ].join("\n");
+  execFileSync(process.execPath, ["--input-type=module", "--eval", script], {
+    cwd: process.cwd(),
+    stdio: "inherit",
+  });
+}
+
 async function main() {
   checkAppcastSparkleVersions();
   checkCliBootstrapExternalImports({
@@ -851,6 +899,15 @@ async function main() {
     },
   });
   await checkPluginSdkExports();
+  const criticalPluginSdkEntrypointErrors = collectCriticalPluginSdkEntrypointSizeErrors();
+  if (criticalPluginSdkEntrypointErrors.length > 0) {
+    console.error("release-check: critical plugin-sdk entrypoint validation failed:");
+    for (const error of criticalPluginSdkEntrypointErrors) {
+      console.error(`  - ${error}`);
+    }
+    process.exit(1);
+  }
+  runCriticalPluginSdkEntrypointImportSmoke();
   checkBundledExtensionMetadata();
   await writePackageDistInventory(process.cwd());
 
diff --git a/src/plugin-sdk/test-helpers/jiti-runtime-api.ts b/src/plugin-sdk/test-helpers/jiti-runtime-api.ts
index 2bc58505a67..60d2ca97002 100644
--- a/src/plugin-sdk/test-helpers/jiti-runtime-api.ts
+++ b/src/plugin-sdk/test-helpers/jiti-runtime-api.ts
@@ -1,7 +1,13 @@
 import { execFileSync } from "node:child_process";
 import { existsSync, readFileSync } from "node:fs";
+import { createRequire } from "node:module";
 import path from "node:path";
-import ts from "typescript";
+
+const nodeRequire = createRequire(import.meta.url);
+
+function loadTypeScript(): typeof import("typescript") {
+  return nodeRequire("typescript") as typeof import("typescript");
+}
 
 const JITI_EXTENSIONS = [
   ".ts",
@@ -79,6 +85,7 @@ function resolveLocalModulePath(filePath: string, specifier: string): string | n
 }
 
 function collectSourceModuleRefs(filePath: string): SourceModuleRef[] {
+  const ts = loadTypeScript();
   const sourceText = readFileSync(filePath, "utf8");
   const sourceFile = ts.createSourceFile(filePath, sourceText, ts.ScriptTarget.Latest, true);
   const refs: SourceModuleRef[] = [];
diff --git a/test/release-check.test.ts b/test/release-check.test.ts
index d951bdfd018..f330bdeb430 100644
--- a/test/release-check.test.ts
+++ b/test/release-check.test.ts
@@ -11,6 +11,7 @@ import {
   collectAppcastSparkleVersionErrors,
   collectBundledExtensionManifestErrors,
   collectBundledPluginRootRuntimeMirrorErrors,
+  collectCriticalPluginSdkEntrypointSizeErrors,
   collectDeclaredRootRuntimeDependencyMetadataErrors,
   collectForbiddenPackContentPaths,
   collectInstalledBundledPluginRuntimeDepErrors,
@@ -21,6 +22,7 @@ import {
   collectPackUnpackedSizeErrors,
   createPackedCliSmokeEnv,
   createPackedBundledPluginPostinstallEnv,
+  MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES,
   PACKED_CLI_SMOKE_COMMANDS,
   packageNameFromSpecifier,
   resolveMissingPackBuildHint,
@@ -729,6 +731,30 @@ describe("collectPackUnpackedSizeErrors", () => {
   });
 });
 
+describe("collectCriticalPluginSdkEntrypointSizeErrors", () => {
+  it("flags oversized plugin SDK test-contract entrypoints before publish", () => {
+    const root = mkdtempSync(join(tmpdir(), "release-check-critical-sdk-"));
+    try {
+      const pluginSdkDir = join(root, "dist", "plugin-sdk");
+      mkdirSync(pluginSdkDir, { recursive: true });
+      writeFileSync(join(pluginSdkDir, "agent-runtime-test-contracts.js"), "export {};\n");
+      writeFileSync(join(pluginSdkDir, "provider-test-contracts.js"), "export {};\n");
+      writeFileSync(
+        join(pluginSdkDir, "plugin-test-contracts.js"),
+        "x".repeat(MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES + 1),
+      );
+
+      expect(collectCriticalPluginSdkEntrypointSizeErrors(root)).toEqual([
+        `dist/plugin-sdk/plugin-test-contracts.js is ${
+          MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES + 1
+        } bytes, exceeding ${MAX_CRITICAL_PLUGIN_SDK_ENTRYPOINT_BYTES} bytes. Keep public SDK test-contract entrypoints lazy and avoid bundling compiler/runtime internals.`,
+      ]);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+});
+
 describe("createPackedBundledPluginPostinstallEnv", () => {
   it("keeps packed postinstall on the lazy bundled dependency path", () => {
     expect(createPackedBundledPluginPostinstallEnv({ PATH: "/usr/bin" })).toEqual({