Feature request: Desktop/notification popup when agent task completes (like OpenCode)

[xiaoqinxing]

Feature Request

Add a completion notification popup when the agent finishes a task, similar to what OpenCode provides.

What OpenCode does

OpenCode shows a desktop notification when the agent finishes its work, so the user can switch to another window/app and get alerted the moment the task is done.

What I'd like

1. Desktop notification – Native OS notification (e.g., via Web Notifications API, Electron-style, or OSC 777 for terminal) when an agent turn/task completes successfully
2. Browser notification – When running pi-web in a browser tab, use the browser's Notification API to pop a toast even if the tab is in the background
3. Configurable – Toggle on/off in Settings, with optional sound
4. Failure alert too – Also notify when a task fails or errors out, not just on success

Use cases

• Run a long agent task, switch to another app, get pinged when it's done
• Monitor multiple sessions in parallel from the browser, get notified when any of them completes
• Know immediately when something errors out instead of discovering it later

Why

This is a huge productivity boost for agentic workflows — no more constantly checking back to see if the agent finished. OpenCode, Claude Code desktop, and many other tools already have this; it would make pi-web feel much more complete.

Thanks for considering!