feat(cli): support /copy in remote sessions using OSC52 (#13471)

packages/cli/src/ui/utils/commandUtils.ts

@@ -7,6 +7,8 @@
 import { debugLogger } from '@google/gemini-cli-core';
 import clipboardy from 'clipboardy';
 import type { SlashCommand } from '../commands/types.js';
+import fs from 'node:fs';
+import type { Writable } from 'node:stream';
 
 /**
  * Checks if a query string potentially represents an '@' command.
@@ -45,8 +47,146 @@ export const isSlashCommand = (query: string): boolean => {
   return true;
 };
 
-// Copies a string snippet to the clipboard
+const ESC = '\u001B';
+const BEL = '\u0007';
+const ST = '\u001B\\';
+
+const MAX_OSC52_SEQUENCE_BYTES = 100_000;
+const OSC52_HEADER = `${ESC}]52;c;`;
+const OSC52_FOOTER = BEL;
+const MAX_OSC52_BODY_B64_BYTES =
+  MAX_OSC52_SEQUENCE_BYTES -
+  Buffer.byteLength(OSC52_HEADER) -
+  Buffer.byteLength(OSC52_FOOTER);
+const MAX_OSC52_DATA_BYTES = Math.floor(MAX_OSC52_BODY_B64_BYTES / 4) * 3;
+
+// Conservative chunk size for GNU screen DCS passthrough.
+const SCREEN_DCS_CHUNK_SIZE = 240;
+
+type TtyTarget = { stream: Writable; closeAfter: boolean } | null;
+
+const pickTty = (): TtyTarget => {
+  // Prefer the controlling TTY to avoid interleaving escape sequences with piped stdout.
+  try {
+    const devTty = fs.createWriteStream('/dev/tty');
+    return { stream: devTty, closeAfter: true };
+  } catch {
+    // fall through
+  }
+  if (process.stderr?.isTTY)
+    return { stream: process.stderr, closeAfter: false };
+  if (process.stdout?.isTTY)
+    return { stream: process.stdout, closeAfter: false };
+  return null;
+};
+
+const inTmux = (): boolean =>
+  Boolean(
+    process.env['TMUX'] || (process.env['TERM'] ?? '').startsWith('tmux'),
+  );
+
+const inScreen = (): boolean =>
+  Boolean(
+    process.env['STY'] || (process.env['TERM'] ?? '').startsWith('screen'),
+  );
+
+const isSSH = (): boolean =>
+  Boolean(
+    process.env['SSH_TTY'] ||
+      process.env['SSH_CONNECTION'] ||
+      process.env['SSH_CLIENT'],
+  );
+
+const isWSL = (): boolean =>
+  Boolean(
+    process.env['WSL_DISTRO_NAME'] ||
+      process.env['WSLENV'] ||
+      process.env['WSL_INTEROP'],
+  );
+
+const isDumbTerm = (): boolean => (process.env['TERM'] ?? '') === 'dumb';
+
+const shouldUseOsc52 = (tty: TtyTarget): boolean =>
+  Boolean(tty) &&
+  !isDumbTerm() &&
+  (isSSH() || inTmux() || inScreen() || isWSL());
+
+const safeUtf8Truncate = (buf: Buffer, maxBytes: number): Buffer => {
+  if (buf.length <= maxBytes) return buf;
+  let end = maxBytes;
+  // Back up to the start of a UTF-8 code point if we cut through a continuation byte (10xxxxxx).
+  while (end > 0 && (buf[end - 1] & 0b1100_0000) === 0b1000_0000) end--;
+  return buf.subarray(0, end);
+};
+
+const buildOsc52 = (text: string): string => {
+  const raw = Buffer.from(text, 'utf8');
+  const safe = safeUtf8Truncate(raw, MAX_OSC52_DATA_BYTES);
+  const b64 = safe.toString('base64');
+  return `${OSC52_HEADER}${b64}${OSC52_FOOTER}`;
+};
+
+const wrapForTmux = (seq: string): string => {
+  // Double ESC bytes in payload without a control-character regex.
+  const doubledEsc = seq.split(ESC).join(ESC + ESC);
+  return `${ESC}Ptmux;${doubledEsc}${ST}`;
+};
+
+const wrapForScreen = (seq: string): string => {
+  let out = '';
+  for (let i = 0; i < seq.length; i += SCREEN_DCS_CHUNK_SIZE) {
+    out += `${ESC}P${seq.slice(i, i + SCREEN_DCS_CHUNK_SIZE)}${ST}`;
+  }
+  return out;
+};
+
+const writeAll = (stream: Writable, data: string): Promise<void> =>
+  new Promise<void>((resolve, reject) => {
+    const onError = (err: unknown) => {
+      cleanup();
+      reject(err as Error);
+    };
+    const onDrain = () => {
+      cleanup();
+      resolve();
+    };
+    const cleanup = () => {
+      stream.off('error', onError);
+      stream.off('drain', onDrain);
+      // Writable.write() handlers may not emit 'drain' if the first write succeeded.
+    };
+    stream.once('error', onError);
+    if (stream.write(data)) {
+      cleanup();
+      resolve();
+    } else {
+      stream.once('drain', onDrain);
+    }
+  });
+
+// Copies a string snippet to the clipboard with robust OSC-52 support.
 export const copyToClipboard = async (text: string): Promise<void> => {
+  if (!text) return;
+
+  const tty = pickTty();
+
+  if (shouldUseOsc52(tty)) {
+    const osc = buildOsc52(text);
+    const payload = inTmux()
+      ? wrapForTmux(osc)
+      : inScreen()
+        ? wrapForScreen(osc)
+        : osc;
+
+    await writeAll(tty!.stream, payload);
+
+    if (tty!.closeAfter) {
+      (tty!.stream as fs.WriteStream).end();
+    }
+    return;
+  }
+
+  // Local / non-TTY fallback
   await clipboardy.write(text);
 };