feat(coding-agent): reduce bundled startup work

packages/coding-agent/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Changed
 
+- Changed the bundled Node.js runtime to load jiti's Babel transform only when an extension needs it, reducing CLI startup time and bundle size.
 - Changed syntax highlighting to initialize only twenty common languages eagerly and defer the remaining grammars until after the initial TUI render, reducing CLI startup time.
 - Changed the Node.js CLI and RPC entrypoints to load a bundled runtime, reducing startup filesystem reads while keeping the public library and legacy module paths on the modular runtime for normal dependency identity.
 - Changed session sharing to render clickable terminal links and Radius shares to display only the artifact's canonical URL.

packages/coding-agent/src/utils/syntax-highlight.ts

@@ -1,4 +1,3 @@
-import { createRequire } from "node:module";
 import hljs from "highlight.js/lib/core.js";
 import bash from "highlight.js/lib/languages/bash.js";
 import c from "highlight.js/lib/languages/c.js";
@@ -22,11 +21,6 @@ import swift from "highlight.js/lib/languages/swift.js";
 import typescript from "highlight.js/lib/languages/typescript.js";
 import { decodeHtmlEntityAt } from "./html.ts";
 
-const moduleRequire = createRequire(import.meta.url);
-declare const PI_BUNDLED_NODE: boolean;
-declare const Bun: unknown;
-declare const require: (specifier: string) => unknown;
-
 const eagerLanguages = {
 	python,
 	java,
@@ -60,18 +54,13 @@ export function loadAllHighlightLanguages(): Promise<void> {
 	if (!allLanguagesPromise) {
 		allLanguagesPromise = new Promise((resolve) => {
 			setImmediate(() => {
-				try {
-					// Static require lets esbuild and Bun include this deferred module in
-					// standalone bundles. Source and unbundled Node runtimes need createRequire.
-					if ((typeof PI_BUNDLED_NODE !== "undefined" && PI_BUNDLED_NODE) || typeof Bun !== "undefined") {
-						require("highlight.js/lib/index.js");
-					} else {
-						moduleRequire("highlight.js/lib/index.js");
-					}
-				} catch {
-					// Eager languages and plaintext fallback remain available.
-				}
-				resolve();
+				void import("highlight.js/lib/index.js").then(
+					() => resolve(),
+					() => {
+						// Eager languages and plaintext fallback remain available.
+						resolve();
+					},
+				);
 			});
 		});
 	}

scripts/build-coding-agent-bundle.mjs

@@ -17,6 +17,7 @@ const banner = {
 };
 const allowedExternalPackages = new Set([
 	"@silvia-odwyer/photon-node",
+	"jiti",
 	// Optional native accelerators. Their callers fall back to JavaScript when absent.
 	"bufferutil",
 	"utf-8-validate",
@@ -24,6 +25,13 @@ const allowedExternalPackages = new Set([
 	"supports-color",
 ]);
 
+const lazyJitiPlugin = {
+	name: "lazy-jiti-transform",
+	setup(build) {
+		build.onResolve({ filter: /^jiti\/static$/ }, () => ({ external: true, path: "jiti" }));
+	},
+};
+
 function commonBuildOptions() {
 	return {
 		absWorkingDir: repoRoot,
@@ -38,6 +46,10 @@ function commonBuildOptions() {
 		minifySyntax: true,
 		minifyWhitespace: true,
 		platform: "node",
+		// The source uses jiti/static so Bun embeds its Babel transform. The Node
+		// package can use regular jiti from its direct dependency and load Babel
+		// only when an extension actually needs transformation.
+		plugins: [lazyJitiPlugin],
 		sourcemap: false,
 		target: "node22.19",
 		// Do not apply the monorepo's source-oriented path aliases while bundling