Show HN: Adrafinil – keep a lid-closed Mac awake only while agents work

rx no. 006 ・ a·draf·i·nil /əˈdræfɪnɪl/ ・ a eugeroic for machines ♡

服用注意 ・ for machines that keep watch after you've gone to sleep.

It's 3 a.m. You're asleep. The agent isn't — it's still mid-thought in a session you started hours ago, and you've closed the lid over it like an eyelid that won't quite shut. caffeinate and Amphetamine are stimulants: they keep the machine wired forever, whether or not anyone's home. Adrafinil is the eugeroic. It does nothing until an agent acquires it, keeps your Mac awake through a closed lid only for as long as that work lives, and clears the moment the last session releases. It only ever wakes for the work — then you both sleep. ♡

Keep your Mac awake only while AI agents are working.

Adrafinil is a macOS menu bar app that prevents the system from sleeping — including clamshell (lid-closed) sleep — exclusively while an AI coding agent has an active session. When no agent is working, sleep behavior is untouched: close the lid and the Mac sleeps normally.

It's the opposite of always-on wake utilities like caffeinate or Amphetamine. Adrafinil only intervenes when an agent (Claude Code, Codex, Cursor, …) is mid-task, and gets out of the way the moment that work finishes.

⚠️ Privileged sleep control. Overriding clamshell sleep requires root. Adrafinil isolates that in a tiny, audited helper that only exposes setSleepBlocked(Bool) — all policy lives in an unprivileged daemon. It holds a standard IOPMAssertion for idle sleep and uses pmset disablesleep for clamshell (lid-closed) sleep, after verifying on-device that the cleaner private IOPMrootDomain paths don't keep a displayless lid-closed Mac awake. See Docs/ARCHITECTURE.md §2.

Download Adrafinil — a signed, notarized disk image. Open it, drag Adrafinil to Applications, and launch. The first launch asks for admin rights once to register the privileged helper. Requires macOS 26.4 or later.

In Xcode, select the Adrafinil scheme and Run. You'll need to set a development team for code signing — the daemon (LaunchAgent) and helper (LaunchDaemon) are embedded into the app bundle and registered with the system when the app launches. (No Team ID is baked into the source; the XPC caller check reads your own signing team at runtime, so a rebuild under any Developer ID authorizes its own components without code changes.)

For a headless compile check without local signing identities:

The shared logic builds and tests standalone as a Swift package:

Agents don't talk to Adrafinil directly. Each agent's hook system calls the bundled CLI:

Holds are activity-scoped, not session-scoped: Claude Code acquires on UserPromptSubmit and releases on Stop, so the Mac is only kept awake while the agent is actually working — an open-but-idle session at the prompt lets it sleep normally.

The daemon refcounts by session key and asks the helper to block sleep while the count is non-zero.

An agent can also keep the Mac awake for a background task that outlives its reply (a long build or deploy) with a time-boxed hold — either by calling adrafinil hold directly or, for MCP-capable agents, through the bundled MCP tool that adrafinil mcp serves:

Other subcommands: status, install-hooks, uninstall-hooks, daemon-status, version.

Four products across three privilege tiers (full detail, including the Xcode project layout, in Docs/ARCHITECTURE.md):

Built by @kageroumado, dispensed at kagerou.glass. The name is a nod to adrafinil — a wakefulness-promoting prodrug — because the app keeps your machine awake only when it actually has work to do.