iTerm2 notifications for coding agents

iTerm2 has three separate ways to alert you, and most people find one of them and assume that's all there is. All three live in the same place: Settings, Profiles, Terminal.

Notification Center Alerts, and the button next to it

Tick "Notification Center Alerts". Then click "Filter Alerts", the button right beside it, because that's where the actual choices are. The modal has separate switches for a bell alert, an idle alert, and escape-sequence-generated alerts. Ticking the outer box without opening this panel is why so many setups half-work.

Escape-sequence alerts are the one Claude Code needs. Claude Code emits an OSC sequence when it wants your attention, and iTerm2 drops it on the floor until this is on. Turn it on and Claude Code's own notifications start reaching Notification Center with no further setup.

Idle alerts are the one worth having

iTerm2 can tell you when a session goes quiet, meaning no output for a while. For agent work that's almost exactly the signal you want, because an agent that stopped producing output has either finished or is sitting on a prompt. It fires whether or not the agent bothered to notify anything, which makes it the most reliable of the three.

I'd turn this on before anything else. It catches the cases where an agent stalls without emitting a sound.

Triggers, for when you want something specific

A trigger matches a regex against terminal output and runs an action. Settings, Profiles, Advanced, then Edit under Triggers. Add a pattern, pick "Post Notification", and you get a banner only for output you care about. "Bounce Dock Icon" bounces until the window is focused, which is harder to miss than a banner that fades.

This is genuinely useful for a specific string you're waiting on. It's also per profile and regex-based, so it's a scalpel rather than a general solution.

One caveat for tmux users: escape-sequence alerts and triggers both work on the byte stream, so tmux swallows them unless you set allow-passthrough on. Idle alerts survive, since they're based on silence rather than content.

Where all three run out

Every one of these is scoped to iTerm2 and scoped to a tab. That's fine until your work isn't.

Run Claude Code in iTerm2, Codex in Ghostty, and Cursor in its own window, and iTerm2 can only speak for a third of it. Even inside iTerm2, an idle alert tells you a session went quiet. It doesn't say which project, which branch, whether that agent is waiting on approval or genuinely finished, or which of your four tabs it was.

AgentNotch reads the agent sessions rather than the terminal, so it covers every terminal and editor at once and knows the difference between waiting for approval, asking a question, and done. The state stays visible until you act on it instead of firing once and fading.

Keep the iTerm2 alerts. Idle alerts especially are free and good. They stop being enough at the point where you have more sessions than you can hold in your head.