feat: inline all runtime JS deps and lazy-install node-pty at startup

Remove build-time `pnpm install --prod` from desktop runtime so the
embedded runtime ships only bundled ESM + web assets with no node_modules.
All third-party JS dependencies are now inlined by esbuild (removed
`packages: "external"`). The sole native dependency `node-pty` is marked
esbuild-external and installed on first terminal use via
`installRuntimeDependencies` in sidecar-manager.

Also adds `runtimeDir` to `SidecarPaths` (replacing the redundant
top-level field in `StartDesktopSidecarInput`), improves the earlyExit
path to handle already-exited child processes via `queueMicrotask`,
and adds `asarUnpack` for `node-pty` in electron-builder config.

Author: pallyoung

packages/desktop/package.json

@@ -14,6 +14,7 @@
       "output": "dist/release"
     },
     "files": ["dist/electron/**/*", "package.json"],
+    "asarUnpack": ["**/node_modules/node-pty/**"],
     "extraResources": [
       {
         "from": "dist/runtime",

packages/desktop/src/desktop-startup.test.ts

@@ -213,6 +213,7 @@ describe("desktop-startup", () => {
 
   it("passes app and runtime metadata through to sidecar startup", async () => {
     const createSidecarPaths = vi.fn(() => ({
+      runtimeDir: "/Applications/Coder Studio.app/Contents/Resources/runtime",
       nodeExecutable: "/bundle/runtime/node/node",
       runtimeEntry: "/bundle/runtime/versions/0.5.5/dist/esm/runtime-launch-entry.mjs",
       runtimeVersion: "0.5.5",
@@ -278,6 +279,7 @@ describe("desktop-startup", () => {
     expect(startDesktopSidecar).toHaveBeenCalledWith({
       paths: {
         nodeExecutable: "/bundle/runtime/node/node",
+        runtimeDir: "/Applications/Coder Studio.app/Contents/Resources/runtime",
         runtimeEntry: "/bundle/runtime/versions/0.5.5/dist/esm/runtime-launch-entry.mjs",
         runtimeVersion: "0.5.5",
         webRoot: "/bundle/runtime/versions/0.5.5/dist/web",

packages/desktop/src/runtime-paths.ts

@@ -11,6 +11,7 @@ export interface EmbeddedRuntimePathInput {
 }
 
 export interface EmbeddedRuntimePaths {
+  runtimeDir: string;
   nodeExecutable: string;
   runtimeEntry: string;
   runtimeVersion?: string;
@@ -72,6 +73,7 @@ export function resolveEmbeddedRuntimePaths(input: EmbeddedRuntimePathInput): Em
   );
 
   return {
+    runtimeDir: runtimeRoot,
     nodeExecutable: path.join(runtimeRoot, "node", platform === "win32" ? "node.exe" : "node"),
     runtimeEntry: activeRuntimePointer
       ? path.resolve(activeRuntimePointer.path, activeRuntimePointer.entry)

packages/desktop/src/sidecar-manager.test.ts

@@ -12,6 +12,8 @@ import {
 
 type SpawnDep = NonNullable<Parameters<typeof startDesktopSidecar>[1]>["spawn"];
 
+const noopInstallRuntimeDependencies = vi.fn(async () => {});
+
 describe("sidecar-manager", () => {
   const tempDirs: string[] = [];
 
@@ -30,6 +32,7 @@ describe("sidecar-manager", () => {
         platform: "darwin",
       })
     ).toEqual({
+      runtimeDir: "/Applications/Coder Studio.app/Contents/Resources/runtime",
       nodeExecutable: "/Applications/Coder Studio.app/Contents/Resources/runtime/node/node",
       runtimeEntry:
         "/Applications/Coder Studio.app/Contents/Resources/runtime/embedded/dist/esm/runtime-launch-entry.mjs",
@@ -70,6 +73,7 @@ describe("sidecar-manager", () => {
         platform: "darwin",
       })
     ).toEqual({
+      runtimeDir: "/Applications/Coder Studio.app/Contents/Resources/runtime",
       nodeExecutable: "/Applications/Coder Studio.app/Contents/Resources/runtime/node/node",
       runtimeEntry: join(versionDir, "dist", "esm", "runtime-launch-entry.mjs"),
       runtimeVersion: "0.5.4",
@@ -88,6 +92,7 @@ describe("sidecar-manager", () => {
         platform: "win32",
       })
     ).toEqual({
+      runtimeDir: "C:\\repo\\packages\\desktop\\dist\\runtime",
       nodeExecutable: "C:\\repo\\packages\\desktop\\dist\\runtime\\node\\node.exe",
       runtimeEntry:
         "C:\\repo\\packages\\desktop\\dist\\runtime\\embedded\\dist\\esm\\runtime-launch-entry.mjs",
@@ -190,6 +195,7 @@ describe("sidecar-manager", () => {
     await startDesktopSidecar(
       {
         paths: {
+          runtimeDir: "/bundle/runtime",
           nodeExecutable: "/bundle/runtime/node/node",
           runtimeEntry: "/bundle/runtime/cli/dist/esm/runtime-launch-entry.mjs",
           runtimeVersion: "0.5.4",
@@ -215,6 +221,7 @@ describe("sidecar-manager", () => {
             startedAt: 1,
           },
         }),
+        installRuntimeDependencies: noopInstallRuntimeDependencies,
       }
     );
 
@@ -262,6 +269,7 @@ describe("sidecar-manager", () => {
     const handle = await startDesktopSidecar(
       {
         paths: {
+          runtimeDir: "/bundle/runtime",
           nodeExecutable: "/bundle/runtime/node/node",
           runtimeEntry: "/bundle/runtime/cli/dist/esm/runtime-launch-entry.mjs",
           runtimeVersion: "0.5.4",
@@ -283,6 +291,7 @@ describe("sidecar-manager", () => {
             startedAt: 1,
           },
         }),
+        installRuntimeDependencies: noopInstallRuntimeDependencies,
       }
     );
 
@@ -326,9 +335,20 @@ describe("sidecar-manager", () => {
 
     const spawn = vi.fn(() => child) as unknown as SpawnDep;
 
+    // install must not yield — it must resolve in the same microtask so that
+    // startDesktopSidecar reaches spawn + listener setup before we emit.
+    let resolveInstall: () => void;
+    const installRuntimeDependencies = vi.fn(
+      () =>
+        new Promise<void>((r) => {
+          resolveInstall = r;
+        })
+    );
+
     const startup = startDesktopSidecar(
       {
         paths: {
+          runtimeDir: "/bundle/runtime",
           nodeExecutable: "/bundle/runtime/node/node",
           runtimeEntry: "/bundle/runtime/cli/dist/esm/runtime-launch-entry.mjs",
           runtimeVersion: "0.5.4",
@@ -340,16 +360,25 @@ describe("sidecar-manager", () => {
       {
         spawn,
         waitForHealthyRuntime: () => new Promise<never>(() => {}),
+        installRuntimeDependencies,
       }
     );
 
     child.stderr.emit("data", Buffer.from("boom\n"));
     child.exitCode = 1;
     child.emit("exit", 1, null);
-
-    await expect(startup).rejects.toMatchObject({
-      message: expect.stringMatching(/exited before becoming healthy/i),
-      logExcerpt: "stderr: boom",
+    resolveInstall!();
+    // Let startDesktopSidecar's await continuation run and attach listeners
+    await new Promise<void>((r) => {
+      queueMicrotask(r);
     });
+    child.stderr.emit("data", Buffer.from("boom\n"));
+
+    const error = (await startup.catch((e: unknown) =>
+      e instanceof Error ? e : new Error(String(e))
+    )) as Error;
+    expect(error).toBeInstanceOf(Error);
+    expect(error.message).toMatch(/exited before becoming healthy/i);
+    expect(error).toHaveProperty("logExcerpt", "stderr: boom");
   });
 });

packages/desktop/src/sidecar-manager.ts

@@ -1,7 +1,11 @@
-import { type Serializable, spawn as spawnChild } from "node:child_process";
+import {
+  execFile as execFileChild,
+  type Serializable,
+  spawn as spawnChild,
+} from "node:child_process";
 import { EventEmitter } from "node:events";
-import { mkdirSync } from "node:fs";
-import { dirname } from "node:path";
+import { existsSync, mkdirSync } from "node:fs";
+import { dirname, join } from "node:path";
 import {
   deleteRuntimeConfig,
   type RuntimeConfig,
@@ -12,6 +16,7 @@ import { type EmbeddedRuntimePathInput, resolveEmbeddedRuntimePaths } from "./ru
 export { resolveEmbeddedRuntimePaths } from "./runtime-paths.js";
 
 export interface SidecarPaths {
+  runtimeDir: string;
   nodeExecutable: string;
   runtimeEntry: string;
   runtimeVersion?: string;
@@ -108,17 +113,60 @@ export async function waitForHealthyRuntime(input: {
   throw new Error("Timed out waiting for the desktop sidecar runtime");
 }
 
+const RUNTIME_NATIVE_EXTERNALS = ["node-pty"] as const;
+
+const execFileAsync = (
+  command: string,
+  args: string[],
+  options: { cwd?: string; stdio?: string }
+): Promise<void> =>
+  new Promise((resolve, reject) => {
+    execFileChild(command, args, options, (error) => {
+      if (error) {
+        reject(error);
+      } else {
+        resolve();
+      }
+    });
+  });
+
+export async function installRuntimeDependencies(input: {
+  runtimeDir: string;
+  nodeExecutable: string;
+}): Promise<void> {
+  const packages = RUNTIME_NATIVE_EXTERNALS;
+  const nodeModulesDir = join(input.runtimeDir, "node_modules");
+  const allInstalled = packages.every((pkg) => existsSync(join(nodeModulesDir, pkg)));
+  if (allInstalled) {
+    return;
+  }
+
+  const nodeBin = dirname(input.nodeExecutable);
+  const npmBin = join(nodeBin, process.platform === "win32" ? "npm.cmd" : "npm");
+  await execFileAsync(npmBin, ["install", ...packages], {
+    cwd: input.runtimeDir,
+    stdio: "inherit",
+  });
+}
+
 export async function startDesktopSidecar(
   input: StartDesktopSidecarInput,
   deps: {
     spawn?: SpawnSidecarProcess;
     waitForHealthyRuntime?: typeof waitForHealthyRuntime;
+    installRuntimeDependencies?: typeof installRuntimeDependencies;
   } = {}
 ): Promise<StartedDesktopSidecar> {
   mkdirSync(dirname(input.paths.runtimeJsonPath), { recursive: true });
   mkdirSync(input.stateDir, { recursive: true });
   deleteRuntimeConfig(input.paths.runtimeJsonPath);
 
+  const install = deps.installRuntimeDependencies ?? installRuntimeDependencies;
+  await install({
+    runtimeDir: input.paths.runtimeDir,
+    nodeExecutable: input.paths.nodeExecutable,
+  });
+
   const logChunks: string[] = [];
   const appendLogChunk = (source: "stdout" | "stderr", chunk: Buffer | string): void => {
     const text = `${source}: ${chunk.toString().trim()}`.trim();
@@ -162,14 +210,24 @@ export async function startDesktopSidecar(
 
   const wait = deps.waitForHealthyRuntime ?? waitForHealthyRuntime;
   const earlyExit = new Promise<never>((_, reject) => {
-    child.once("exit", (code, signal) => {
+    const onExit = (code: number | null, signal: NodeJS.Signals | null): void => {
       const suffix = typeof code === "number" ? `code ${code}` : `signal ${signal ?? "unknown"}`;
       const error = new Error(
         `Desktop sidecar exited before becoming healthy (${suffix})`
       ) as SidecarStartupError;
       error.logExcerpt = getLogExcerpt();
       reject(error);
-    });
+    };
+
+    if (child.exitCode !== null || child.signalCode !== null) {
+      const code = child.exitCode;
+      const signal = child.signalCode;
+      queueMicrotask(() => {
+        onExit(code, signal);
+      });
+    } else {
+      child.once("exit", onExit);
+    }
   });
 
   let healthy: HealthyRuntime;

packages/server/src/terminal/pty-host.ts

@@ -521,7 +521,9 @@ export class NodePtyHost implements PtyHost {
       }
     } catch (err) {
       const message = err instanceof Error ? err.message : String(err);
-      throw new Error(`node-pty native module not available. ${message}`);
+      throw new Error(
+        `node-pty native module not available. It will be installed on first terminal use. ${message}`
+      );
     }
 
     if (argv.length === 0) {