Presence

A native macOS menu-bar app that notices when you step away from your Mac and raises a privacy curtain over your screens until you come back and confirm it's you — using the camera entirely on-device, and Apple's own authentication to restore.

Built for OpenAI Build Week 2026. Core functionality implemented by Codex (GPT-5.6); see AI collaboration.

What it does

• Presence detection — the built-in camera (never an iPhone/Continuity camera) runs Apple Vision face + human detection locally at ≤5 fps. No frame ever leaves your Mac.
• Privacy curtain — when you're away past a grace period (default 30 s), a frosted curtain obscures every display. Restoring it goes through Touch ID or your password via Apple's LocalAuthentication — Presence has no unlock path of its own.
• Additional-viewer warning — optionally raises the curtain when a second person is visible behind you for a sustained interval.
• Policies in plain English — type "protect my screen when I walk away for 45 seconds" and compile it to a policy. With the Codex CLI installed, GPT-5.6 does the compiling (via your existing Codex plan — no API key, no cost; discovered at Homebrew/standard paths, or point the codexPath user default at your install; live calls are budgeted — see SECURITY.md); otherwise a built-in deterministic template compiler handles common phrasings. Either way the output is untrusted input: it passes a strict schema validator, you see a plain-language preview plus the raw JSON, and nothing takes effect until you explicitly approve it.
• Event history — a closed-schema local log (state changes only, never images), with one-click Delete All. "Explain recent events" can send the sanitized log — previewed verbatim first, sent only when you click Send — to GPT-5.6 for a plain-English summary.
• Simulator mode — scripted scenarios (walk away, lean away, second viewer, camera loss) run through the real state machine with a visible SIMULATOR badge, so you can see the whole flow with no camera access at all.
• Status HUD — an optional floating panel showing live state, person count, and confidence, legible from across the room.

What it never does

• It is not a login replacement. Presence never touches loginwindow, PAM, the authorization database, or FileVault, and never stores or replays your password. It is not "Face ID for Mac" — restoration is Apple's LocalAuthentication prompt, nothing else.
• Camera data never leaves the device. No frames, embeddings, or identity data are ever written to disk¹ or sent anywhere, including to GPT-5.6. Flow E sends only the text you typed; Flow F sends only the sanitized event schema you previewed.
• The model is outside the trust boundary. GPT-5.6 output is text that must survive validation and your explicit approval. It cannot execute anything, and a response can trigger nothing.
• You always have an exit. Pause from the menu bar, quit with ⌘Q, kill -9 recovers cleanly (protected state never persists), repeated crashes trigger safe mode, and creating ~/.presence-disable disables the app entirely.

¹ Except a developer fixture-capture mode that is compiled out of release builds and also requires an explicit --fixture-capture launch flag.

Requirements & build

• macOS 26 (Tahoe) on Apple silicon; built-in camera for live monitoring (simulator mode works without one).
• Xcode Command Line Tools (Swift 6.3). No Xcode, no third-party dependencies.

git clone https://github.com/Solarthis/presence-macos.git
cd presence-macos
./verify.sh     # build + 173-check suite + safety gates
./build.sh      # produces signed Presence.app
open Presence.app

Release archives on the Releases page are signed with the maintainer's Apple Development identity. Building from source, ./build.sh signs with your own identity if you set PRESENCE_SIGN_ID=<identity>, and otherwise falls back to ad-hoc signing — the app runs identically, but macOS re-prompts for camera permission after each rebuild.

verify.sh is the single verification entry point: it builds, runs the assert-based check suite (state machine scenarios, hostile policy fixtures, timing-isolation and authentication-boundary structural checks), and enforces source-level gates (PresenceCore stays free of camera/UI frameworks; no hard-coded safety timing in the app layer; no login-path mechanisms anywhere).

Architecture (short version)

Two layers, enforced by a build gate:

• PresenceCore — pure logic, no AppKit/AVFoundation/Vision: the deterministic state machine (launch guard → awaiting presence → present → grace → protected → restore), policy schema + validator, JSON extractor, template compiler.
• Presence (app) — AVFoundation camera source, Vision perception, curtain windows, LocalAuthentication gate, menu bar, policy store/UI, event store.

Production timing is structurally isolated from demo timing: the production entry point takes no configuration and always derives from safe defaults (30 s launch guard, 30 s grace); compressed demo timing exists only behind explicit scripted-run entry points and --simulate/--live-test flags. Automated checks and source gates enforce this.

See docs/ and TESTING.md for details and evidence.

Known limitations

• App hiding is cut. NSRunningApplication.hide() proved unreliable on macOS 26 (spike-tested, 3 attempts). The hideApps policy action is stored but inert, and the preview says so. The curtain is the protective action.
• Displays-off is honest about locking: turning displays off locks your Mac only if "Require password immediately" is enabled in System Settings — Presence cannot verify that setting, and the UI says exactly that. Off by default.
• Presence is a privacy courtesy layer against shoulder-surfing and walk-away exposure. It is not a security boundary against a determined local attacker — your locked screen is.

AI collaboration

This project was built for OpenAI Build Week with an explicit AI division of labor:

• Codex (GPT-5.6, gpt-5.6-sol) implemented the core functionality — state machine, curtain/safety mechanics, LocalAuthentication restore, camera/perception pipeline, policy schema/validator/compiler, and event system — across recorded codex exec sessions, primarily one PRIMARY session. Session IDs and scopes: CODEX_SESSIONS.md.
• Claude (Claude Fable 5, via Claude Code) orchestrated: wrote slice specifications, reviewed every diff independently, ran verification, managed git/GitHub, and wrote the documentation.
• At runtime, GPT-5.6 (via the user's own Codex CLI plan) optionally compiles plain-English policy text and summarizes event history — always behind validation, preview, and explicit human approval.

License

MIT — see LICENSE.