Fixed packaged desktop app backend crash by inlining JS deps and symlinking _modules

- Changed server tsdown config to bundle all dependencies except native
  addons (node-pty) and packages needing runtime require.resolve
  (@github/copilot-sdk) into a self-contained bin.mjs
- Updated desktop artifact build to install only external deps via npm,
  then rename node_modules to _modules (electron-builder strips node_modules)
- Added ensureBackendModulesSymlink() in desktop main process that creates
  a node_modules -> _modules symlink at runtime before spawning the backend
  (NODE_PATH does not work for ESM module resolution)

Author: youpele52

apps/desktop/src/backend/backendManager.ts

@@ -6,7 +6,11 @@ import {
   captureBackendOutput,
   writeBackendSessionBoundary,
 } from "../logging/logging";
-import { resolveBackendCwd, resolveBackendEntry } from "../env/pathResolver";
+import {
+  ensureBackendModulesSymlink,
+  resolveBackendCwd,
+  resolveBackendEntry,
+} from "../env/pathResolver";
 import type { RotatingFileSink } from "@bigcode/shared/logging";
 import { readPersistedBackendObservabilitySettings } from "../logging/logging";
 
@@ -103,6 +107,10 @@ export function startBackend(): void {
   const backendLogSink = _deps.getBackendLogSink();
   const captureBackendLogs = backendLogSink !== null;
 
+  // Ensure _modules → node_modules symlink exists for ESM resolution of
+  // external native packages (e.g. @github/copilot-sdk, node-pty).
+  ensureBackendModulesSymlink();
+
   // Always pipe stderr so we can capture crash output for diagnostics,
   // regardless of whether a log sink is configured.
   const child = ChildProcess.spawn(process.execPath, [backendEntry, "--bootstrap-fd", "3"], {

apps/desktop/src/env/pathResolver.ts

@@ -168,6 +168,48 @@ export function resolveBackendCwd(rootDir: string): string {
   return OS.homedir();
 }
 
+/**
+ * Ensures native/external modules are resolvable in packaged builds.
+ *
+ * electron-builder silently strips directories named `node_modules` from
+ * extraResources copies.  The build script works around this by renaming the
+ * server's `node_modules` to `_modules`.  At runtime we create a
+ * `node_modules` → `_modules` **symlink** so that Node.js ESM resolution
+ * (which walks up the directory tree looking for `node_modules/`) can find the
+ * external packages normally.
+ *
+ * `NODE_PATH` is intentionally NOT used because Node.js ESM resolution ignores
+ * it — only CJS honours `NODE_PATH`.
+ *
+ * No-ops in dev (modules resolve normally from the monorepo).
+ */
+export function ensureBackendModulesSymlink(): void {
+  if (!app.isPackaged) return;
+
+  const serverDir = Path.join(process.resourcesPath, "server");
+  const modulesDir = Path.join(serverDir, "_modules");
+  const symlinkPath = Path.join(serverDir, "node_modules");
+
+  if (!FS.existsSync(modulesDir)) return;
+
+  // If the symlink already exists (e.g. from a previous launch) skip creation.
+  try {
+    const stat = FS.lstatSync(symlinkPath);
+    if (stat.isSymbolicLink()) return;
+    // Not a symlink — something unexpected.  Remove and recreate.
+    FS.rmSync(symlinkPath, { recursive: true, force: true });
+  } catch {
+    // Does not exist yet — good, we'll create it below.
+  }
+
+  try {
+    // Relative symlink so the .app bundle stays relocatable.
+    FS.symlinkSync("_modules", symlinkPath, "dir");
+  } catch (err) {
+    console.error("[desktop] failed to create node_modules symlink:", err);
+  }
+}
+
 // ---------------------------------------------------------------------------
 // Desktop static asset resolution
 // ---------------------------------------------------------------------------

apps/server/tsdown.config.ts

@@ -1,5 +1,31 @@
 import { defineConfig } from "tsdown";
 
+// Packages that MUST remain external and cannot be inlined into the bundle:
+// - node-pty: native C++ addon (.node binary + spawn-helper executable); also
+//   resolved at runtime via createRequire/require.resolve in NodePTY.ts.
+// - @github/copilot-sdk, @github/copilot: CopilotAdapter.types.ts uses
+//   require.resolve("@github/copilot-sdk") at runtime to locate the sibling
+//   @github/copilot CLI entry point on disk.
+// - @effect/sql-sqlite-bun, @effect/platform-bun: Bun-only; wrap bun:sqlite
+//   and Bun built-in APIs. Never loaded in an Electron/Node context.
+//
+// Everything else (effect, @effect/platform-node, @anthropic-ai/claude-agent-sdk,
+// @opencode-ai/sdk, @pierre/diffs, open, @bigcode/*) is inlined to produce a
+// self-contained bundle that does not require a node_modules tree at runtime.
+// This is critical for packaged desktop builds where the server runs under
+// Electron's Node.js via ELECTRON_RUN_AS_NODE=1.
+const EXTERNAL_PACKAGES = [
+  "node-pty",
+  "@github/copilot-sdk",
+  "@github/copilot",
+  "@effect/sql-sqlite-bun",
+  "@effect/platform-bun",
+];
+
+function isExternal(id: string): boolean {
+  return EXTERNAL_PACKAGES.some((pkg) => id === pkg || id.startsWith(`${pkg}/`));
+}
+
 export default defineConfig({
   entry: ["src/bin.ts"],
   format: ["esm", "cjs"],
@@ -9,7 +35,9 @@ export default defineConfig({
   outDir: "dist",
   sourcemap: true,
   clean: true,
-  noExternal: (id) => id.startsWith("@bigcode/"),
+  // Bundle ALL dependencies into the output except the explicitly external ones.
+  // noExternal: true tells the bundler to inline everything by default.
+  noExternal: (id) => !isExternal(id),
   inlineOnly: false,
   banner: {
     js: "#!/usr/bin/env node\n",

scripts/lib/desktop-artifact/build.ts

@@ -25,6 +25,23 @@ import {
 } from "./resources.ts";
 import { resolveCatalogDependencies } from "../resolve-catalog.ts";
 
+// Packages that are NOT inlined by tsdown and must be installed at runtime.
+// Must be kept in sync with EXTERNAL_PACKAGES in apps/server/tsdown.config.ts.
+// Bun-only externals (@effect/sql-sqlite-bun, @effect/platform-bun) are excluded
+// because they are never loaded in the Electron/Node.js desktop runtime.
+const SERVER_RUNTIME_EXTERNAL_PACKAGES = new Set(["node-pty", "@github/copilot-sdk"]);
+
+/** Filter a dependency map to only include packages that are external at runtime. */
+function pickExternalDependencies(dependencies: Record<string, unknown>): Record<string, unknown> {
+  const result: Record<string, unknown> = {};
+  for (const [name, version] of Object.entries(dependencies)) {
+    if (SERVER_RUNTIME_EXTERNAL_PACKAGES.has(name)) {
+      result[name] = version;
+    }
+  }
+  return result;
+}
+
 export const buildDesktopArtifact = Effect.fn("buildDesktopArtifact")(function* (
   options: ResolvedBuildOptions,
 ) {
@@ -123,6 +140,11 @@ export const buildDesktopArtifact = Effect.fn("buildDesktopArtifact")(function*
   yield* assertPlatformBuildResources(options.platform, stageResourcesDir, options.verbose);
   yield* fs.copy(stageResourcesDir, path.join(stageAppDir, "apps/desktop/prod-resources"));
 
+  // The server bundle is self-contained (all JS dependencies inlined by tsdown).
+  // Only packages that cannot be bundled (native addons, runtime require.resolve)
+  // need to be installed in the staged server directory.
+  const serverExternalDependencies = pickExternalDependencies(resolvedServerDependencies);
+
   const stagePackageJson: StagePackageJson = {
     name: "bigcode-desktop",
     version: appVersion,
@@ -141,7 +163,7 @@ export const buildDesktopArtifact = Effect.fn("buildDesktopArtifact")(function*
       options.mockUpdateServerPort,
     ),
     dependencies: {
-      ...resolvedServerDependencies,
+      ...serverExternalDependencies,
       ...resolvedDesktopRuntimeDependencies,
     },
     devDependencies: {
@@ -159,7 +181,7 @@ export const buildDesktopArtifact = Effect.fn("buildDesktopArtifact")(function*
     type: serverPackageJson.type,
     bin: serverPackageJson.bin,
     files: serverPackageJson.files,
-    dependencies: resolvedServerDependencies,
+    dependencies: serverExternalDependencies,
   };
   const stageServerPackageJsonString = yield* encodeJsonString(stageServerPackageJson);
   yield* fs.writeFileString(
@@ -175,14 +197,27 @@ export const buildDesktopArtifact = Effect.fn("buildDesktopArtifact")(function*
       shell: process.platform === "win32",
     })`bun install --production`,
   );
+  // Use npm (not bun) for the server directory so node_modules follows the
+  // standard flat layout that Node.js expects. Bun's symlink-based hoisting
+  // does not survive electron-builder's file copy to extraResources.
   yield* runCommand(
     ChildProcess.make({
       cwd: stageServerDir,
       ...commandOutputOptions(options.verbose),
       shell: process.platform === "win32",
-    })`bun install --production`,
+    })`npm install --production --no-optional`,
   );
 
+  // electron-builder silently strips node_modules from extraResources copies.
+  // Rename to _modules so the directory survives into the packaged app.
+  // The desktop main process sets NODE_PATH to _modules when spawning the
+  // backend child process so Node.js can still resolve these external packages.
+  const serverNodeModules = path.join(stageServerDir, "node_modules");
+  const serverModulesRenamed = path.join(stageServerDir, "_modules");
+  if (yield* fs.exists(serverNodeModules)) {
+    yield* fs.rename(serverNodeModules, serverModulesRenamed);
+  }
+
   const buildEnv: NodeJS.ProcessEnv = { ...process.env };
   for (const [key, value] of Object.entries(buildEnv)) {
     if (value === "") {