OSC 52 clipboard support for SSH/mosh

[gturkoglu]

/copy fails over SSH with "install xclip or xsel" but my terminal supports OSC 52 just fine. Would be nice if pi detected remote sessions and used OSC 52 instead of trying native clipboard tools.

PR #415 already did this for OAuth URLs. Same approach for copyToClipboard() in packages/coding-agent/src/utils/clipboard.ts.

[gturkoglu]

I tried this as an extension first and it works fine. It registers /lcopy and uses OSC 52, pulling the last assistant message from the current branch (so tree navigation works). Code below:

import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";

function copyViaOSC52(text: string): void {
  const encoded = Buffer.from(text).toString("base64");
  process.stdout.write(`\x1b]52;c;${encoded}\x07`);
}

function getLastAssistantText(entries: any[]): string | undefined {
  for (let i = entries.length - 1; i >= 0; i--) {
    const entry = entries[i];
    if (entry.type === "message" && entry.message?.role === "assistant") {
      let text = "";
      for (const part of entry.message.content ?? []) {
        if (part.type === "text") text += part.text;
      }
      if (text) return text;
    }
  }
  return undefined;
}

export default function (pi: ExtensionAPI) {
  pi.registerCommand("lcopy", {
    description: "Copy last agent message via OSC 52",
    handler: async (_args, ctx) => {
      const entries = ctx.sessionManager.getBranch();
      const text = getLastAssistantText(entries);
      if (!text) {
        ctx.ui.notify("No agent message to copy", "warning");
        return;
      }
      copyViaOSC52(text);
      ctx.ui.notify("Copied to local clipboard (OSC 52)", "info");
    },
  });
}

This convinced me OSC 52 is the right direction; would be great to have it in core so /copy just works over SSH.