fix: fall back to node-pty when Bun is not defined (Electron/Node.js) (#1446)

Co-authored-by: Letta Code <noreply@letta.com>

build.js

@@ -49,7 +49,7 @@ await Bun.build({
   // Keep most native Node.js modules external to avoid bundling issues
   // But don't make `sharp` external, causes issues with global Bun-based installs
   // ref: #745, #1200
-  external: ["ws", "@vscode/ripgrep"],
+  external: ["ws", "@vscode/ripgrep", "node-pty"],
   features: features,
 });
 

package.json

@@ -73,7 +73,7 @@
     "test:update-chain:manual": "bun run src/tests/update-chain-smoke.ts --mode manual",
     "test:update-chain:startup": "bun run src/tests/update-chain-smoke.ts --mode startup",
     "prepublishOnly": "bun run build",
-    "postinstall": "node scripts/postinstall-patches.js || echo letta: vendor patches skipped"
+    "postinstall": "node scripts/postinstall-patches.js || echo letta: vendor patches skipped && node -e \"try{require('fs').chmodSync(require('path').join(require.resolve('node-pty/package.json'),'../prebuilds/darwin-arm64/spawn-helper'),0o755)}catch(e){}\" || true"
   },
   "lint-staged": {
     "*.{ts,tsx,js,jsx,json}": [

src/websocket/terminalHandler.ts

@@ -2,29 +2,33 @@
  * PTY terminal handler for listen mode.
  * Manages interactive terminal sessions spawned by the web UI.
  *
- * Uses Bun's native Bun.Terminal API (available since Bun v1.3.5)
- * for real PTY support without node-pty.
+ * Runtime strategy:
+ * - Bun  → Bun.spawn with terminal option (native PTY, no node-pty needed)
+ * - Node.js / Electron → node-pty (Bun.spawn unavailable; node-pty's libuv
+ *   poll handles integrate correctly with Node.js but NOT with Bun's event loop)
  */
 
 import * as os from "node:os";
 import WebSocket from "ws";
 
+const IS_BUN = typeof Bun !== "undefined";
+
+// 16ms debounce window for output batching; flush immediately at 64 KB
+// to prevent unbounded string growth on high-throughput commands.
+const FLUSH_INTERVAL_MS = 16;
+const MAX_BUFFER_BYTES = 64 * 1024;
+
 interface TerminalSession {
-  process: ReturnType<typeof Bun.spawn>;
-  terminal: {
-    write: (data: string) => void;
-    resize: (cols: number, rows: number) => void;
-    close: () => void;
-  };
+  write: (data: string) => void;
+  resize: (cols: number, rows: number) => void;
+  kill: () => void;
+  pid: number;
   terminalId: string;
   spawnedAt: number;
 }
 
 const terminals = new Map<string, TerminalSession>();
 
-/**
- * Get the default shell for the current platform.
- */
 function getDefaultShell(): string {
   if (os.platform() === "win32") {
     return process.env.COMSPEC || "cmd.exe";
@@ -32,9 +36,6 @@ function getDefaultShell(): string {
   return process.env.SHELL || "/bin/zsh";
 }
 
-/**
- * Send a terminal message back to the web client via the device WebSocket.
- */
 function sendTerminalMessage(
   socket: WebSocket,
   message: Record<string, unknown>,
@@ -44,9 +45,177 @@ function sendTerminalMessage(
   }
 }
 
-/**
- * Spawn a new PTY terminal session using Bun's native Terminal API.
- */
+/** Create a flush-on-size-or-timer output batcher. */
+function makeOutputBatcher(
+  onFlush: (data: string) => void,
+): (chunk: string) => void {
+  let buffer = "";
+  let timer: ReturnType<typeof setTimeout> | null = null;
+
+  const flush = () => {
+    if (timer) {
+      clearTimeout(timer);
+      timer = null;
+    }
+    if (buffer.length > 0) {
+      onFlush(buffer);
+      buffer = "";
+    }
+  };
+
+  return (chunk: string) => {
+    buffer += chunk;
+    if (buffer.length >= MAX_BUFFER_BYTES) {
+      flush();
+    } else if (!timer) {
+      timer = setTimeout(flush, FLUSH_INTERVAL_MS);
+    }
+  };
+}
+
+// ── Bun spawn ──────────────────────────────────────────────────────────────
+
+function spawnBun(
+  shell: string,
+  cwd: string,
+  cols: number,
+  rows: number,
+  terminal_id: string,
+  socket: WebSocket,
+): TerminalSession {
+  const handleData = makeOutputBatcher((data) =>
+    sendTerminalMessage(socket, { type: "terminal_output", terminal_id, data }),
+  );
+
+  const proc = Bun.spawn([shell], {
+    cwd,
+    env: { ...process.env, TERM: "xterm-256color", COLORTERM: "truecolor" },
+    terminal: {
+      cols: cols || 80,
+      rows: rows || 24,
+      data: (_t: unknown, chunk: Uint8Array) =>
+        handleData(new TextDecoder().decode(chunk)),
+    },
+  });
+
+  const terminal = (
+    proc as unknown as {
+      terminal: {
+        write: (d: string) => void;
+        resize: (c: number, r: number) => void;
+        close: () => void;
+      };
+    }
+  ).terminal;
+
+  if (!terminal) {
+    throw new Error("Bun.spawn terminal object missing — API unavailable");
+  }
+
+  proc.exited.then((exitCode) => {
+    const current = terminals.get(terminal_id);
+    if (current && current.pid === proc.pid) {
+      terminals.delete(terminal_id);
+      sendTerminalMessage(socket, {
+        type: "terminal_exited",
+        terminal_id,
+        exitCode: exitCode ?? 0,
+      });
+    }
+  });
+
+  return {
+    write: (d) => {
+      try {
+        terminal.write(d);
+      } catch {}
+    },
+    resize: (c, r) => {
+      try {
+        terminal.resize(c, r);
+      } catch {}
+    },
+    kill: () => {
+      try {
+        terminal.close();
+      } catch {}
+      try {
+        proc.kill();
+      } catch {}
+    },
+    pid: proc.pid,
+    terminalId: terminal_id,
+    spawnedAt: Date.now(),
+  };
+}
+
+// ── node-pty spawn (Node.js / Electron) ───────────────────────────────────
+
+function spawnNodePty(
+  shell: string,
+  cwd: string,
+  cols: number,
+  rows: number,
+  terminal_id: string,
+  socket: WebSocket,
+): TerminalSession {
+  // eslint-disable-next-line @typescript-eslint/no-require-imports
+  const pty = require("node-pty") as typeof import("node-pty");
+
+  const handleData = makeOutputBatcher((data) =>
+    sendTerminalMessage(socket, { type: "terminal_output", terminal_id, data }),
+  );
+
+  const ptyProcess = pty.spawn(shell, [], {
+    name: "xterm-256color",
+    cols: cols || 80,
+    rows: rows || 24,
+    cwd,
+    env: {
+      ...(process.env as Record<string, string>),
+      TERM: "xterm-256color",
+      COLORTERM: "truecolor",
+    },
+  });
+
+  ptyProcess.onData(handleData);
+
+  ptyProcess.onExit(({ exitCode }) => {
+    const current = terminals.get(terminal_id);
+    if (current && current.pid === ptyProcess.pid) {
+      terminals.delete(terminal_id);
+      sendTerminalMessage(socket, {
+        type: "terminal_exited",
+        terminal_id,
+        exitCode: exitCode ?? 0,
+      });
+    }
+  });
+
+  return {
+    write: (d) => {
+      try {
+        ptyProcess.write(d);
+      } catch {}
+    },
+    resize: (c, r) => {
+      try {
+        ptyProcess.resize(c, r);
+      } catch {}
+    },
+    kill: () => {
+      try {
+        ptyProcess.kill();
+      } catch {}
+    },
+    pid: ptyProcess.pid,
+    terminalId: terminal_id,
+    spawnedAt: Date.now(),
+  };
+}
+
+// ── Public API ─────────────────────────────────────────────────────────────
+
 export function handleTerminalSpawn(
   msg: { terminal_id: string; cols: number; rows: number },
   socket: WebSocket,
@@ -54,111 +223,56 @@ export function handleTerminalSpawn(
 ): void {
   const { terminal_id, cols, rows } = msg;
 
-  // Kill existing session with same ID if any
-  killTerminal(terminal_id);
+  // React Strict Mode fires mount→unmount→mount which produces spawn→kill→spawn
+  // in rapid succession. The kill is already ignored (< 2s guard below), but the
+  // second spawn would normally kill and restart. If the session is < 2s old and
+  // still alive, reuse it and resend terminal_spawned instead.
+  const existing = terminals.get(terminal_id);
+  if (existing && Date.now() - existing.spawnedAt < 2000) {
+    let alive = true;
+    try {
+      existing.write("\r");
+    } catch {
+      alive = false;
+    }
 
-  const shell = getDefaultShell();
-
-  console.log(
-    `[Terminal] Spawning PTY: shell=${shell}, cwd=${cwd}, cols=${cols}, rows=${rows}`,
-  );
-
-  try {
-    const proc = Bun.spawn([shell], {
-      cwd,
-      env: {
-        ...process.env,
-        TERM: "xterm-256color",
-        COLORTERM: "truecolor",
-      },
-      terminal: {
-        cols: cols || 80,
-        rows: rows || 24,
-        data: (() => {
-          // Batch output chunks within a 16ms window into a single WS message
-          // to avoid flooding the WebSocket with many small frames.
-          let buffer = "";
-          let flushTimer: ReturnType<typeof setTimeout> | null = null;
-
-          return (_terminal: unknown, data: Uint8Array) => {
-            buffer += new TextDecoder().decode(data);
-
-            if (!flushTimer) {
-              flushTimer = setTimeout(() => {
-                if (buffer.length > 0) {
-                  sendTerminalMessage(socket, {
-                    type: "terminal_output",
-                    terminal_id,
-                    data: buffer,
-                  });
-                  buffer = "";
-                }
-                flushTimer = null;
-              }, 16);
-            }
-          };
-        })(),
-      },
-    });
-
-    // The terminal object is available on the proc when using the terminal option
-    const terminal = (
-      proc as unknown as { terminal: TerminalSession["terminal"] }
-    ).terminal;
-
-    console.log(
-      `[Terminal] proc.pid=${proc.pid}, terminal=${typeof terminal}, keys=${Object.keys(proc as unknown as Record<string, unknown>).join(",")}`,
-    );
-
-    if (!terminal) {
-      console.error(
-        "[Terminal] terminal object is undefined on proc — Bun.Terminal API may not be available",
+    if (alive) {
+      console.log(
+        `[Terminal] Reusing session (age=${Date.now() - existing.spawnedAt}ms), pid=${existing.pid}`,
       );
       sendTerminalMessage(socket, {
-        type: "terminal_exited",
+        type: "terminal_spawned",
         terminal_id,
-        exitCode: 1,
+        pid: existing.pid,
       });
       return;
     }
 
-    const session: TerminalSession = {
-      process: proc,
-      terminal,
-      terminalId: terminal_id,
-      spawnedAt: Date.now(),
-    };
+    // Session dead — fall through to spawn a fresh one
+    terminals.delete(terminal_id);
+  }
+
+  killTerminal(terminal_id);
+
+  const shell = getDefaultShell();
+  console.log(
+    `[Terminal] Spawning PTY (${IS_BUN ? "bun" : "node-pty"}): shell=${shell}, cwd=${cwd}, cols=${cols}, rows=${rows}`,
+  );
+
+  try {
+    const session = IS_BUN
+      ? spawnBun(shell, cwd, cols, rows, terminal_id, socket)
+      : spawnNodePty(shell, cwd, cols, rows, terminal_id, socket);
+
     terminals.set(terminal_id, session);
     console.log(
-      `[Terminal] Session stored for terminal_id=${terminal_id}, map size=${terminals.size}`,
+      `[Terminal] Session stored for terminal_id=${terminal_id}, pid=${session.pid}`,
     );
 
-    // Handle process exit — only clean up if this is still the active session
-    // (a newer spawn may have replaced us in the map)
-    const myPid = proc.pid;
-    proc.exited.then((exitCode) => {
-      const current = terminals.get(terminal_id);
-      if (current && current.process.pid === myPid) {
-        console.log(
-          `[Terminal] PTY process exited: terminal_id=${terminal_id}, pid=${myPid}, exitCode=${exitCode}`,
-        );
-        terminals.delete(terminal_id);
-        sendTerminalMessage(socket, {
-          type: "terminal_exited",
-          terminal_id,
-          exitCode: exitCode ?? 0,
-        });
-      } else {
-        console.log(
-          `[Terminal] Stale PTY exit ignored: terminal_id=${terminal_id}, pid=${myPid} (current pid=${current?.process.pid})`,
-        );
-      }
-    });
-
     sendTerminalMessage(socket, {
       type: "terminal_spawned",
       terminal_id,
-      pid: proc.pid,
+      pid: session.pid,
     });
   } catch (error) {
     console.error("[Terminal] Failed to spawn PTY:", error);
@@ -170,41 +284,23 @@ export function handleTerminalSpawn(
   }
 }
 
-/**
- * Write input data to a terminal session.
- */
 export function handleTerminalInput(msg: {
   terminal_id: string;
   data: string;
 }): void {
-  const session = terminals.get(msg.terminal_id);
-  if (session) {
-    session.terminal.write(msg.data);
-  }
+  terminals.get(msg.terminal_id)?.write(msg.data);
 }
 
-/**
- * Resize a terminal session.
- */
 export function handleTerminalResize(msg: {
   terminal_id: string;
   cols: number;
   rows: number;
 }): void {
-  const session = terminals.get(msg.terminal_id);
-  if (session) {
-    session.terminal.resize(msg.cols, msg.rows);
-  }
+  terminals.get(msg.terminal_id)?.resize(msg.cols, msg.rows);
 }
 
-/**
- * Kill a terminal session.
- */
 export function handleTerminalKill(msg: { terminal_id: string }): void {
   const session = terminals.get(msg.terminal_id);
-  // Ignore kill if the session was spawned very recently (< 2s).
-  // This handles the React Strict Mode race where cleanup's kill arrives
-  // after the remount's spawn due to async WS relay latency.
   if (session && Date.now() - session.spawnedAt < 2000) {
     console.log(
       `[Terminal] Ignoring kill for recently spawned session (age=${Date.now() - session.spawnedAt}ms)`,
@@ -218,22 +314,13 @@ function killTerminal(terminalId: string): void {
   const session = terminals.get(terminalId);
   if (session) {
     console.log(
-      `[Terminal] killTerminal: terminalId=${terminalId}, pid=${session.process.pid}`,
+      `[Terminal] killTerminal: terminalId=${terminalId}, pid=${session.pid}`,
     );
-    try {
-      session.terminal.close();
-    } catch {
-      // terminal may already be closed
-    }
-    session.process.kill();
+    session.kill();
     terminals.delete(terminalId);
   }
 }
 
-/**
- * Kill all active terminal sessions.
- * Call on disconnect/cleanup.
- */
 export function killAllTerminals(): void {
   for (const [id] of terminals) {
     killTerminal(id);