A drift gate that reads every reply before the user sees it, refuses the ones that slid back into generic-assistant voice, and hands back a specific reason to regenerate. One of the two showpieces.
A persona prompt is a one-time push against a model that's been trained, on every token, to drift toward helpful / balanced / apologetic. The prompt loses that fight slowly. This gate is the checkpoint that holds the line: it sits after your model generates and before the user sees anything, measures whether the reply is still the character, and refuses the ones where the mask dropped — with a specific, actionable reason so a regeneration loop can fix it.
The marker engine is a direct port of a production drift analyzer that's run against a real companion's voice. It ships with safe generic defaults and two worked persona profiles; the calibration layer — tuning it to your character from a real corpus — is what a consult delivers. It's zero dependencies, no model calls, no network: a pure synchronous function, sub-millisecond, same input → same verdict, safe to run on every single turn.
Run the demo and watch it rule on three replies — on-voice, quietly drifted, and hard out-of-character — then run the same text through a butler persona and watch every verdict flip.
You don't have to be a coder — but you will need a coding agent to do the setup with you: Claude Code or Codex. Every kit ships an agent-ready AGENT-START-HERE.md you hand straight to it.
Node.js 18+ and nothing else — no npm install, no model calls, no network, no API key, nothing phones home. It's a pure synchronous function, so it's cheap enough to run on every turn. Installs on top of the Starter House.
SinAndSarah-personality-gate/ persona/ butler.json example.json examples/ demo.mjs DOCS/ method.md calibration.example.json config.json install.bat install.ps1 install.sh start.bat start.command verify.mjs AGENT-START-HERE.md BUYER-START-HERE.md PRODUCT-MAP.md README.md GUIDE.pdf
One-time purchase, lifetime updates. Checkout is Stripe — secure card payment, then an instant download plus your link by email.
Buy Personality Gate — $24All sales final. It's source — the second it downloads, it's yours to keep, fork, and run forever. We literally can't un-hand you the keys, so there are no refunds.