diff --git a/extensions/diffs-language-pack/package.json b/extensions/diffs-language-pack/package.json
index 13ebed0bce5c..9c0e8e8780b0 100644
--- a/extensions/diffs-language-pack/package.json
+++ b/extensions/diffs-language-pack/package.json
@@ -28,6 +28,7 @@
       "build": "node --import tsx ../../scripts/build-diffs-viewer-runtime.mts full"
     },
     "build": {
+      "bundledDist": false,
       "openclawVersion": "2026.8.1",
       "staticAssets": [
         {
diff --git a/extensions/diffs/package.json b/extensions/diffs/package.json
index 5b1784756dc7..0d81272e36ec 100644
--- a/extensions/diffs/package.json
+++ b/extensions/diffs/package.json
@@ -34,6 +34,7 @@
       "build": "node --import tsx ../../scripts/build-diffs-viewer-runtime.mts curated"
     },
     "build": {
+      "bundledDist": false,
       "openclawVersion": "2026.8.1",
       "staticAssets": [
         {
diff --git a/package.json b/package.json
index c9a2c64fb339..918ca5f1041f 100644
--- a/package.json
+++ b/package.json
@@ -1517,7 +1517,7 @@
     "audit:seams": "node --import tsx scripts/audit-seams.mts",
     "build": "node --import tsx scripts/build-all.mts",
     "build:ci-artifacts": "node --import tsx scripts/build-all.mts ciArtifacts",
-    "build:docker": "node --import tsx scripts/tsdown-build.mts && node --import tsx scripts/check-cli-bootstrap-imports.mts && node scripts/runtime-postbuild.mjs && node --import tsx scripts/build-stamp.mts && node --import tsx scripts/runtime-postbuild-stamp.mts && pnpm plugins:assets:build && pnpm plugins:assets:copy && node --import tsx scripts/write-build-info.ts && node --import tsx scripts/write-cli-startup-metadata.ts",
+    "build:docker": "pnpm plugins:assets:build && node --import tsx scripts/tsdown-build.mts && node --import tsx scripts/check-cli-bootstrap-imports.mts && node scripts/runtime-postbuild.mjs && node --import tsx scripts/build-stamp.mts && node --import tsx scripts/runtime-postbuild-stamp.mts && pnpm plugins:assets:copy && node --import tsx scripts/write-build-info.ts && node --import tsx scripts/write-cli-startup-metadata.ts",
     "build:package": "node --import tsx scripts/build-all.mts package",
     "build:plugin-sdk:dts": "node scripts/run-tsgo.mjs -p tsconfig.plugin-sdk.dts.json --declaration true",
     "build:plugin-sdk:strict-smoke": "node --import tsx scripts/tsdown-build.mts && node scripts/runtime-postbuild.mjs && node --import tsx scripts/run-with-env.mts OPENCLAW_PLUGIN_SDK_CANONICAL_DTS=1 -- node --import tsx scripts/write-plugin-sdk-entry-dts.ts && node --import tsx scripts/check-plugin-sdk-exports.mts",
diff --git a/scripts/lib/bundled-plugin-build-entries-types.d.ts b/scripts/lib/bundled-plugin-build-entries-types.d.ts
index efee305008ce..818b2b1782bf 100644
--- a/scripts/lib/bundled-plugin-build-entries-types.d.ts
+++ b/scripts/lib/bundled-plugin-build-entries-types.d.ts
@@ -14,6 +14,7 @@ export type BundledPluginBuildEntryParams = {
 
 export const NON_PACKAGED_BUNDLED_PLUGIN_DIRS: Set<string>;
 export const DOCKER_SELECTED_PLUGIN_BUILD_IDS_ENV: string;
+export function parseDockerSelectedPluginBuildIdFilter(env?: NodeJS.ProcessEnv): Set<string> | null;
 export function collectPluginSourceEntries(packageJson: unknown): string[];
 export function collectTopLevelPublicSurfaceEntries(pluginDir: string): string[];
 export function collectRootPackageExcludedExtensionDirs(
diff --git a/scripts/lib/bundled-plugin-build-entries.mjs b/scripts/lib/bundled-plugin-build-entries.mjs
index a03c696f0fe8..66928904fbc6 100644
--- a/scripts/lib/bundled-plugin-build-entries.mjs
+++ b/scripts/lib/bundled-plugin-build-entries.mjs
@@ -37,7 +37,7 @@ function parseBundledPluginBuildIdFilter(env = process.env) {
   );
 }
 
-function parseDockerSelectedPluginBuildIdFilter(env = process.env) {
+export function parseDockerSelectedPluginBuildIdFilter(env = process.env) {
   const raw = env[DOCKER_SELECTED_PLUGIN_BUILD_IDS_ENV];
   if (typeof raw !== "string" || raw.trim() === "") {
     return null;
diff --git a/scripts/lib/static-extension-assets.mts b/scripts/lib/static-extension-assets.mts
index fc141e714881..b35868941524 100644
--- a/scripts/lib/static-extension-assets.mts
+++ b/scripts/lib/static-extension-assets.mts
@@ -2,6 +2,7 @@
 import { spawnSync } from "node:child_process";
 import fs from "node:fs";
 import path from "node:path";
+import { parseDockerSelectedPluginBuildIdFilter } from "./bundled-plugin-build-entries.mjs";
 import { isRecord } from "./record-shared.mjs";
 
 type StaticExtensionAsset = {
@@ -13,6 +14,7 @@ type StaticExtensionAsset = {
 type StaticExtensionAssetParams = {
   rootDir?: string;
   fs?: typeof fs;
+  env?: NodeJS.ProcessEnv;
   includeExternalPlugins?: boolean;
   assets?: StaticExtensionAsset[];
   warn?: (message: string) => void;
@@ -164,6 +166,7 @@ export function discoverStaticExtensionAssets(params: StaticExtensionAssetParams
   const rootDir = params.rootDir ?? process.cwd();
   const fsImpl = params.fs ?? fs;
   const includeExternalPlugins = params.includeExternalPlugins ?? false;
+  const dockerSelectedPluginIds = parseDockerSelectedPluginBuildIdFilter(params.env ?? process.env);
   const assets: StaticExtensionAsset[] = [];
   for (const { dirName, hasPackageJson, packageJsonPath } of listExtensionPackageDirs(
     rootDir,
@@ -173,7 +176,11 @@ export function discoverStaticExtensionAssets(params: StaticExtensionAssetParams
       continue;
     }
     const packageJson = readJsonFile(packageJsonPath, fsImpl);
-    if (!includeExternalPlugins && isExternalDistPackage(packageJson)) {
+    if (
+      !includeExternalPlugins &&
+      isExternalDistPackage(packageJson) &&
+      !dockerSelectedPluginIds?.has(dirName)
+    ) {
       continue;
     }
     for (const entry of readPackageStaticAssetEntries(packageJson)) {
@@ -196,7 +203,8 @@ function discoverStaticExtensionRuntimeOverlayAssets(params: StaticExtensionAsse
   const rootDir = params.rootDir ?? process.cwd();
   const fsImpl = params.fs ?? fs;
   const assetsByDest = new Map<string, StaticExtensionAsset>();
-  for (const asset of params.assets ?? discoverStaticExtensionAssets({ rootDir, fs: fsImpl })) {
+  for (const asset of params.assets ??
+    discoverStaticExtensionAssets({ rootDir, fs: fsImpl, env: params.env })) {
     assetsByDest.set(asset.dest, asset);
   }
   for (const { dirName, packageDir } of listDistExtensionPackageDirs(rootDir, fsImpl)) {
@@ -278,7 +286,8 @@ export function listGeneratedExtensionAssetSources(params: StaticExtensionAssetP
 export function copyStaticExtensionAssets(params: StaticExtensionAssetParams = {}) {
   const rootDir = params.rootDir ?? process.cwd();
   const fsImpl = params.fs ?? fs;
-  const assets = params.assets ?? discoverStaticExtensionAssets({ rootDir, fs: fsImpl });
+  const assets =
+    params.assets ?? discoverStaticExtensionAssets({ rootDir, fs: fsImpl, env: params.env });
   const warn = params.warn ?? console.warn;
   for (const { src, dest } of assets) {
     const srcPath = path.join(rootDir, src);
@@ -332,7 +341,12 @@ export function copyStaticExtensionAssetsForPackage(
   const fsImpl = params.fs ?? fs;
   const assets =
     params.assets ??
-    discoverStaticExtensionAssets({ rootDir, fs: fsImpl, includeExternalPlugins: true });
+    discoverStaticExtensionAssets({
+      rootDir,
+      fs: fsImpl,
+      env: params.env,
+      includeExternalPlugins: true,
+    });
   const packagePrefix = `extensions/${params.pluginDir}/`;
   const rootDistPrefix = `dist/extensions/${params.pluginDir}/`;
   const copied: string[] = [];
diff --git a/test/package-scripts.test.ts b/test/package-scripts.test.ts
index 3651a234649e..326c05338334 100644
--- a/test/package-scripts.test.ts
+++ b/test/package-scripts.test.ts
@@ -182,6 +182,17 @@ describe("package scripts", () => {
     );
   });
 
+  it("builds generated plugin assets before Docker runtime postbuild", () => {
+    const commands = expectDefined(
+      readPackageJson().scripts["build:docker"],
+      "package script build:docker",
+    ).split(" && ");
+
+    expect(commands.indexOf("pnpm plugins:assets:build")).toBeLessThan(
+      commands.indexOf("node scripts/runtime-postbuild.mjs"),
+    );
+  });
+
   it("cleans package builds before validating release contents", () => {
     const scripts = readPackageJson().scripts;
 
diff --git a/test/scripts/build-external-plugin-local-dist.test.ts b/test/scripts/build-external-plugin-local-dist.test.ts
index 4f0bfc2aa575..82eabbc24bb8 100644
--- a/test/scripts/build-external-plugin-local-dist.test.ts
+++ b/test/scripts/build-external-plugin-local-dist.test.ts
@@ -13,9 +13,15 @@ describe("external plugin local dist build", () => {
     const packageDirs = listExternalPluginLocalDistPackageDirs();
     const excludedPluginIds = collectRootPackageExcludedExtensionDirs();
 
-    expect(packageDirs).toHaveLength(61);
+    expect(packageDirs).toHaveLength(63);
     expect(packageDirs).toEqual(
-      expect.arrayContaining(["extensions/slack", "extensions/sms", "extensions/mxc"]),
+      expect.arrayContaining([
+        "extensions/diffs",
+        "extensions/diffs-language-pack",
+        "extensions/slack",
+        "extensions/sms",
+        "extensions/mxc",
+      ]),
     );
     expect(packageDirs).not.toContain("extensions/whatsapp");
     expect(
diff --git a/test/scripts/bundled-plugin-build-entries.test.ts b/test/scripts/bundled-plugin-build-entries.test.ts
index fdcf9ea45add..9a7922a6a315 100644
--- a/test/scripts/bundled-plugin-build-entries.test.ts
+++ b/test/scripts/bundled-plugin-build-entries.test.ts
@@ -196,7 +196,14 @@ describe("bundled plugin build entries", () => {
     const entries = listBundledPluginBuildEntries();
     const artifacts = listBundledPluginPackArtifacts();
 
-    for (const pluginId of ["copilot", "openshell", "slack", "tokenjuice"]) {
+    for (const pluginId of [
+      "copilot",
+      "diffs",
+      "diffs-language-pack",
+      "openshell",
+      "slack",
+      "tokenjuice",
+    ]) {
       expectNoPrefixMatches(Object.keys(entries), `extensions/${pluginId}/`);
       expectNoPrefixMatches(artifacts, `dist/extensions/${pluginId}/`);
     }
diff --git a/test/scripts/runtime-postbuild.test.ts b/test/scripts/runtime-postbuild.test.ts
index 55152b0eab63..1e6f4722cb37 100644
--- a/test/scripts/runtime-postbuild.test.ts
+++ b/test/scripts/runtime-postbuild.test.ts
@@ -108,8 +108,6 @@ describe("runtime postbuild static assets", () => {
       "dist/extensions/acpx/mcp-command-line.mjs",
       "dist/extensions/acpx/mcp-proxy.mjs",
       "dist/extensions/crabbox/assets/openclaw-worker-wallpaper.png",
-      "dist/extensions/diffs-language-pack/assets/viewer-runtime.js",
-      "dist/extensions/diffs/assets/viewer-runtime.js",
       "dist/extensions/discord/assets/embedded-app-sdk.mjs",
       "dist/extensions/onepassword/onepassword-op-path.js",
       "dist/extensions/onepassword/onepassword-secret-id.js",
@@ -117,8 +115,10 @@ describe("runtime postbuild static assets", () => {
       "dist/extensions/vault/vault-secret-id.js",
       "dist/extensions/vault/vault-secret-ref-resolver.js",
     ]);
-    expect(payload.sources).toContain("extensions/diffs-language-pack/assets/viewer-runtime.js");
-    expect(payload.sources).toContain("extensions/diffs/assets/viewer-runtime.js");
+    expect(payload.sources).not.toContain(
+      "extensions/diffs-language-pack/assets/viewer-runtime.js",
+    );
+    expect(payload.sources).not.toContain("extensions/diffs/assets/viewer-runtime.js");
     expect(payload.sources).toContain("extensions/discord/assets/embedded-app-sdk.mjs");
     expect(payload.sources).toContain("extensions/crabbox/assets/openclaw-worker-wallpaper.png");
   });
@@ -177,7 +177,15 @@ describe("runtime postbuild static assets", () => {
     expect(discoverStaticExtensionAssets({ rootDir })).toEqual([]);
   });
 
-  it("excludes external plugin (bundledDist: false) static assets by default", async () => {
+  it.each([
+    { name: "normal root build", params: {}, included: false },
+    { name: "isolated external build", params: { includeExternalPlugins: true }, included: true },
+    {
+      name: "Docker-selected build",
+      params: { env: { OPENCLAW_INTERNAL_DOCKER_BUILD_PLUGIN_IDS: "external-demo" } },
+      included: true,
+    },
+  ])("$name handles external plugin assets", async ({ params, included }) => {
     const rootDir = createTempDir("openclaw-runtime-postbuild-");
     const packageDir = path.join(rootDir, "extensions", "external-demo");
     await fs.mkdir(packageDir, { recursive: true });
@@ -200,39 +208,17 @@ describe("runtime postbuild static assets", () => {
       "utf8",
     );
 
-    expect(discoverStaticExtensionAssets({ rootDir })).toEqual([]);
-  });
-
-  it("includes external plugin (bundledDist: false) static assets when includeExternalPlugins is true", async () => {
-    const rootDir = createTempDir("openclaw-runtime-postbuild-");
-    const packageDir = path.join(rootDir, "extensions", "external-demo");
-    await fs.mkdir(packageDir, { recursive: true });
-    await fs.writeFile(
-      path.join(packageDir, "package.json"),
-      JSON.stringify({
-        name: "@openclaw/external-demo",
-        openclaw: {
-          build: {
-            bundledDist: false,
-            staticAssets: [
-              {
-                source: "./assets/runtime.js",
-                output: "assets/runtime.js",
-              },
-            ],
-          },
-        },
-      }),
-      "utf8",
+    expect(discoverStaticExtensionAssets({ rootDir, ...params })).toEqual(
+      included
+        ? [
+            {
+              pluginDir: "external-demo",
+              src: "extensions/external-demo/assets/runtime.js",
+              dest: "dist/extensions/external-demo/assets/runtime.js",
+            },
+          ]
+        : [],
     );
-
-    expect(discoverStaticExtensionAssets({ rootDir, includeExternalPlugins: true })).toEqual([
-      {
-        pluginDir: "external-demo",
-        src: "extensions/external-demo/assets/runtime.js",
-        dest: "dist/extensions/external-demo/assets/runtime.js",
-      },
-    ]);
   });
 
   it("copies declared static assets into root and package dist", async () => {