Full-Stack Product & Systems Engineer | Founder at RoleLane
Edinburgh, Scotland, UK | rolelane.co.uk

I build multi-tenant SaaS products, deterministic financial backends, and low-footprint Linux systems where your tenant boundaries and your money maths aren't allowed to drift.

When you're shipping billing, margin controls, or compliance workflows for real businesses, "mostly right" isn't good enough. I don't rely on hidden UI buttons for authorisation, and I won't let binary floats touch our commercial ledgers. Instead, I enforce row-level isolation directly inside PostgreSQL 17, price every contract in exact integer minor units (pence and cents) or fractions.Fraction, and gate every pull request we merge behind automated E2E and security-invariant checks.

Multi-tenant UK staffing, rate-card margin, compliance, and billing SaaS that I've built and operate from Edinburgh.

We handle shift lifecycles, statutory compliance checks, rate-card margin calculations, and client invoicing inside one workspace, and we make sure agencies and client teams can't read a single row outside their own boundary. Under the hood, we run PostgreSQL 17 FORCE ROW LEVEL SECURITY across 70+ tables under a least-privilege NOBYPASSRLS runtime role, paired with Laravel 12 / PHP 8.4, Vue 3 / Inertia v2, PHPStan Level 8, and Playwright E2E suites.

• msfPDF · Live Browser Compiler
  Sub-millisecond (0.16–0.52 ms) zero-rendering-dependency %PDF-1.4 vector document engine with byte-identical SHA-256 parity across Rust, Web-Standard TypeScript (0 runtime npm dependencies — Node, Cloudflare Workers, Browser), and an 810 KB standalone CLI. Bypasses 500 MB headless Chromium bloat and HTML/SVG SSRF risks by compiling declarative JSON specs (A4, Letter, and 80 mm thermal slips) into pure 7-bit ASCII streams — featuring built-in Latin (/WinAnsiEncoding), Russian Cyrillic (Русский / ₽ / №), and connected Arabic RTL (العربية contextual shaping, Lam-Alef ligatures, UAX #9 BiDi, and /ToUnicode CMaps with zero .ttf files), pure GF(256) vector QR codes, exact integer minor-unit maths (GBP, EUR, USD, BRL, JPY, RUB, AED, SAR), llms.txt + Agent SKILL.md discovery manifests, and an atomic 0600 multi-tenant vault.
• ledger-guard
  My hexagonal Python 3.12 commercial order pricing, exact Fraction unit-of-measure conversion, and four-eyes margin-approval reference engine. Features live Model Context Protocol (POST /mcp) JSON-RPC tools and FastAPI HTTP routes sharing identical RBAC boundaries. Verified Publisher & Live Monitored on the M8ven Trust Index, backed by PostgreSQL 17 FORCE RLS DDL and 65 OWASP ASVS Level 2 tests.
• hybridbox
  An async Python (FastAPI + WebSockets) and Linux/ARM64 systems bridge I wrote so you can turn spare Android hardware into low-latency headless Linux/X11 and media appliances instead of leaving good silicon in a drawer.

1. Deterministic Money & Margin Maths: If you split a 3-pack case (1/3 ratio) or spread header discounts across lines, our fractions.Fraction and ROUND_HALF_EVEN minor-unit arithmetic won't leak pennies, and pass-through freight never inflates your margin basis.
2. Database-Enforced Tenant Isolation: We pair PostgreSQL 17 FORCE ROW LEVEL SECURITY with two-stage transaction-local context binding, optimistic concurrency version checks, and SHA-256 payload-bound idempotency (409 on mismatch).
3. Dual-Transport AI & Web Security: Whether your team hits REST endpoints or connects an AI copilot over MCP tools, you get identical server-side RBAC, HMAC-SHA256 multi-bucket rate limiters, per-request CSP nonces, and Luhn PAN log redaction.
4. Core Stack & CI Gates: I work daily across Python 3.12 (FastAPI, uv, pytest, mypy --strict, ruff), PHP 8.4 (Laravel 12, PHPStan Level 8), Rust (Axum, Tokio, <15 MB single-binary daemons), TypeScript (Vue 3, Playwright), and PostgreSQL 17 on Linux.