Native macOS POC Results

This document records capability evidence, not the production product specification. Canonical direction is defined by ../../CONTEXT.md, ../product/mastermind-product-brief.md, and ../architecture/native-mastermind.md.

Implemented

SwiftPM-based macOS POC under native/MastermindPOC.
AppKit lifecycle with a menu bar status item.
Transparent non-activating overlay window with hide/show and click-through controls.
Overlay window uses NSWindowSharingType.none and ScreenCaptureKit filtering excludes the current process windows from app-owned capture.
ScreenCaptureKit screen stream proof with frame counters.
ScreenCaptureKit system audio proof with best-effort PCM extraction to 16 kHz mono signed 16-bit little-endian frames.
AVAudioEngine microphone proof with 16 kHz mono signed 16-bit little-endian frames.
Separate microphone and system audio counters in the overlay.
Compact HUD controls for Settings, Hide, and Quit.
Draggable overlay title area.
Settings panel with persisted overlay background opacity.
Swift unit tests for status labels, PCM frame metadata, PCM S16LE encoding, and separate audio counters.
App bundle build script at native/MastermindPOC/scripts/build-app.sh.

Verified Automatically

swift test passes for MastermindPOCCore.
swift build --product MastermindPOC compiles the native executable.
native/MastermindPOC/scripts/build-app.sh produces native/MastermindPOC/build/MastermindPOC.app.
Existing Electron local provider tests pass when run outside the managed sandbox restrictions.

Manual Verification Needed

Launch native/MastermindPOC/build/MastermindPOC.app.
Confirm the menu bar item is visible while the app runs.
Confirm the overlay appears locally and can be hidden.
Confirm the overlay can be dragged by its top title bar.
Confirm the overlay Settings button opens the settings panel.
Confirm the opacity slider changes only the HUD background opacity and persists across relaunches.
Confirm the overlay Quit button exits the app.
Confirm click-through lets pointer events pass to apps underneath.
Grant Screen Recording permission when macOS prompts, then restart the POC if needed.
Start Screen + System Audio and confirm screen frame and system PCM counters increase.
Start Microphone and confirm microphone PCM counters increase while speaking.
Confirm Pause All Capture stops screen, system audio, and microphone updates.
Confirm app-owned screen capture does not include the Mastermind overlay.

Boundary

This POC is not a stealth or anti-detection system. It shows a menu bar item while running, requests normal macOS permissions, and only excludes its own overlay from the context it captures for itself.

Role in production migration

native/MastermindPOC proves that AppKit windowing, ScreenCaptureKit screen and system-audio capture, AVAudioEngine microphone capture, current-process exclusion, and 16 kHz PCM conversion are viable.

Production development moves to native/Mastermind. Validated capability code may be ported behind production boundaries, but the POC is not renamed into the product and is retired after parity checks pass.

The production design intentionally differs from the POC:

the Companion Island is hidden at launch and anchored to the primary display's top center;
enabled Collectors start continuously after onboarding instead of through manual start menu items;
the Menu Bar Item uses a stable glyph with detailed states inside its menu;
screen, microphone, and system-audio states are simultaneous per-Collector states rather than one TrustStatus;
settings and management live inside the expanded Companion Island;
screen context follows the active display rather than always selecting the main display;
the Context Graph, Local Provider, local ASR client, retention, encryption, Context Receipts, and Activity Log are production requirements not implemented by the POC.

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