diff --git a/package.json b/package.json
index 52c6e0b..c80587a 100644
--- a/package.json
+++ b/package.json
@@ -54,8 +54,14 @@
     "scripts/postinstall.cjs",
     "dist/cli.d.ts",
     "dist/cli.js",
+    "dist/core-cli.d.ts",
+    "dist/core-cli.js",
     "dist/core.d.ts",
     "dist/core.js",
+    "dist/external-command.d.ts",
+    "dist/external-command.js",
+    "dist/launcher.d.ts",
+    "dist/launcher.js",
     "README.md",
     "LICENSE"
   ],
@@ -67,15 +73,15 @@
     "check:public-boundary": "node scripts/check-public-boundary.mjs",
     "build": "tsc -p tsconfig.json --noEmit && tsc -p tsconfig.eval.json --noEmit",
     "build:eval": "tsc -p tsconfig.eval.json --noEmit",
-    "build:lib": "tsc -p tsconfig.build.json",
-    "build:cli": "bun build src/cli.ts --compile --outfile dist/agent-memory --define __VERSION__=\"'$(node -p \"require('./package.json').version\")'\"",
+    "build:lib": "tsc -p tsconfig.build.json && node scripts/assemble-portable-cli.cjs",
+    "build:cli": "bun build src/launcher.ts --compile --outfile dist/agent-memory --define __VERSION__=\"'$(node -p \"require('./package.json').version\")'\"",
     "eval:feedback": "bun eval/run.ts",
     "prepare": "npm run build:lib",
     "prepack": "npm run check:public-boundary && npm run build:lib",
     "lint": "biome check .",
     "test": "bun test test/unit.test.ts",
     "test:unit": "bun test test/unit.test.ts",
-    "test:cli": "bun test test/cli.test.ts --timeout 15000",
+    "test:cli": "bun test test/cli.test.ts test/external-command.test.ts --timeout 15000",
     "test:eval": "bun test test/eval.test.ts"
   },
   "devDependencies": {
diff --git a/scripts/assemble-portable-cli.cjs b/scripts/assemble-portable-cli.cjs
new file mode 100644
index 0000000..edc04db
--- /dev/null
+++ b/scripts/assemble-portable-cli.cjs
@@ -0,0 +1,18 @@
+const fs = require("node:fs");
+const path = require("node:path");
+
+const root = path.resolve(__dirname, "..");
+const dist = path.join(root, "dist");
+const cli = path.join(dist, "cli.js");
+const cliTypes = path.join(dist, "cli.d.ts");
+const coreCli = path.join(dist, "core-cli.js");
+const coreCliTypes = path.join(dist, "core-cli.d.ts");
+const launcher = path.join(dist, "launcher.js");
+
+for (const target of [cli, launcher]) {
+	if (!fs.existsSync(target)) throw new Error(`Missing build output: ${path.relative(root, target)}`);
+}
+
+fs.copyFileSync(cli, coreCli);
+if (fs.existsSync(cliTypes)) fs.copyFileSync(cliTypes, coreCliTypes);
+fs.copyFileSync(launcher, cli);
diff --git a/scripts/check-public-boundary.mjs b/scripts/check-public-boundary.mjs
index 84f818e..6dbc0f0 100644
--- a/scripts/check-public-boundary.mjs
+++ b/scripts/check-public-boundary.mjs
@@ -18,9 +18,21 @@ const rules = [
   "SmF5IFplbmc=",
 ].map(decode);
 
+// Keep the MIT implementation surface intentionally small. Adding another source
+// module requires an explicit boundary review instead of merely choosing a neutral
+// filename that happens not to match the lexical rules below.
+const allowedSourceFiles = new Set([
+  "src/core.ts",
+  "src/cli.ts",
+  "src/external-command.ts",
+  "src/launcher.ts",
+]);
+
 const tracked = execFileSync("git", ["ls-files", "-z"], { encoding: "utf8" }).split("\0").filter(Boolean);
 const violations = [];
 for (const file of tracked) {
+  if (file.startsWith("src/") && file.endsWith(".ts") && !allowedSourceFiles.has(file)) violations.push(file);
+
   let data;
   try {
     data = fs.readFileSync(file);
diff --git a/src/external-command.ts b/src/external-command.ts
new file mode 100644
index 0000000..56978ac
--- /dev/null
+++ b/src/external-command.ts
@@ -0,0 +1,58 @@
+import { spawnSync } from "node:child_process";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+
+const CORE_COMMANDS = new Set([
+	"help",
+	"version",
+	"install-skills",
+	"uninstall-skills",
+	"context",
+	"write",
+	"read",
+	"scratchpad",
+	"search",
+	"distil",
+	"distill",
+	"sync",
+	"init",
+	"status",
+]);
+
+const COMMAND_NAME = /^[a-z][a-z0-9]*(?:-[a-z0-9]+)*$/;
+
+export function shouldTryExternalCommand(command: string | undefined): boolean {
+	return Boolean(command && COMMAND_NAME.test(command) && !CORE_COMMANDS.has(command));
+}
+
+export function resolveExternalCommandHost(options?: {
+	homeDir?: string;
+	platform?: NodeJS.Platform;
+	isFile?: (target: string) => boolean;
+}): string | null {
+	const homeDir = options?.homeDir ?? os.homedir();
+	const platform = options?.platform ?? process.platform;
+	const isFile =
+		options?.isFile ??
+		((target: string) => {
+			try {
+				return fs.statSync(target).isFile();
+			} catch {
+				return false;
+			}
+		});
+	const filename = platform === "win32" ? "agent-memory-extension.exe" : "agent-memory-extension";
+	const target = path.join(homeDir, ".agent-memory", "bin", filename);
+	return isFile(target) ? target : null;
+}
+
+export function runExternalCommand(host: string, argv: string[]): number {
+	const result = spawnSync(host, argv, {
+		stdio: "inherit",
+		env: process.env,
+		windowsHide: true,
+	});
+	if (result.error) throw result.error;
+	return result.status ?? 1;
+}
diff --git a/src/launcher.ts b/src/launcher.ts
new file mode 100644
index 0000000..2f106d2
--- /dev/null
+++ b/src/launcher.ts
@@ -0,0 +1,41 @@
+#!/usr/bin/env node
+
+import * as path from "node:path";
+import { fileURLToPath } from "node:url";
+import { resolveExternalCommandHost, runExternalCommand, shouldTryExternalCommand } from "./external-command.js";
+
+async function runCoreCli(): Promise<void> {
+	// The npm package keeps dist/cli.js as the public bin for compatibility. During
+	// packaging the launcher is copied to that path and the original CLI moves to
+	// dist/core-cli.js. Keep the portable-only import dynamic so TypeScript does not
+	// require that generated file at source-check time. The standalone Bun build
+	// still sees the static ./cli.js import and bundles Core normally.
+	const runningAsPortableBin = path.basename(fileURLToPath(import.meta.url)) === "cli.js";
+	if (runningAsPortableBin) {
+		const portableCoreCli = `./core-${"cli"}.js`;
+		await import(portableCoreCli);
+		return;
+	}
+	await import("./cli.js");
+}
+
+async function main(): Promise<void> {
+	const command = process.argv[2];
+	if (!shouldTryExternalCommand(command)) {
+		await runCoreCli();
+		return;
+	}
+
+	const host = resolveExternalCommandHost();
+	if (!host) {
+		await runCoreCli();
+		return;
+	}
+
+	process.exitCode = runExternalCommand(host, process.argv.slice(2));
+}
+
+main().catch((error) => {
+	console.error(error instanceof Error ? error.message : String(error));
+	process.exitCode = 1;
+});
diff --git a/test/external-command.test.ts b/test/external-command.test.ts
new file mode 100644
index 0000000..5278421
--- /dev/null
+++ b/test/external-command.test.ts
@@ -0,0 +1,62 @@
+import { describe, expect, test } from "bun:test";
+import * as path from "node:path";
+
+import { resolveExternalCommandHost, shouldTryExternalCommand } from "../src/external-command.js";
+
+describe("external command handoff", () => {
+	test("keeps core commands in the public CLI", () => {
+		for (const command of [
+			"help",
+			"version",
+			"install-skills",
+			"uninstall-skills",
+			"context",
+			"write",
+			"read",
+			"scratchpad",
+			"search",
+			"distil",
+			"distill",
+			"sync",
+			"init",
+			"status",
+		]) {
+			expect(shouldTryExternalCommand(command)).toBe(false);
+		}
+		expect(shouldTryExternalCommand(undefined)).toBe(false);
+		expect(shouldTryExternalCommand("--help")).toBe(false);
+	});
+
+	test("accepts only safe non-core command names", () => {
+		expect(shouldTryExternalCommand("recall")).toBe(true);
+		expect(shouldTryExternalCommand("session-recall")).toBe(true);
+		expect(shouldTryExternalCommand("../recall")).toBe(false);
+		expect(shouldTryExternalCommand("Recall")).toBe(false);
+		expect(shouldTryExternalCommand("recall/foo")).toBe(false);
+	});
+
+	test("resolves one fixed user-local host path", () => {
+		const homeDir = path.join(path.sep, "tmp", "home");
+		const expected = path.join(homeDir, ".agent-memory", "bin", "agent-memory-extension");
+		expect(
+			resolveExternalCommandHost({
+				homeDir,
+				platform: "linux",
+				isFile: (target) => target === expected,
+			}),
+		).toBe(expected);
+		expect(resolveExternalCommandHost({ homeDir, platform: "linux", isFile: () => false })).toBeNull();
+	});
+
+	test("uses an executable suffix on Windows", () => {
+		const homeDir = "C:\\Users\\test";
+		const expected = path.join(homeDir, ".agent-memory", "bin", "agent-memory-extension.exe");
+		expect(
+			resolveExternalCommandHost({
+				homeDir,
+				platform: "win32",
+				isFile: (target) => target === expected,
+			}),
+		).toBe(expected);
+	});
+});