Yonatan Valencia

Two hosts behind one front door, neither with an inbound port open

Since August 2026 every publicly reachable hostname is served from AWS Lightsail (us-east-2): the payroll API, the Rails platform across its four tenants, the static apps, and the only cloudflared actually running. Static IP, port 80 closed, container-level self-healing I measured by freezing the process on purpose — 47 s to recovery. Because both hosts reach the internet through outbound-only Cloudflare Tunnels, moving production between them did not change a single DNS record. The single-node home lab in Medellín — Intel i5-4570T, 7.2 GB RAM, Ubuntu 25.04 — now has its tunnel stopped and publishes nothing: it holds the agent fleet, the read-only panels, host monitoring, and a standby whose containers are up but unreachable, carrying the same commit, the same signing key and the same database. The Rails half of that standby stays deliberately off, and that is the most useful thing the migration taught me: with both copies running they exhausted the database pooler's connections and split traffic across two versions of the app, which is how one tenant's login started rendering another tenant's brand. Failover is manual and one-way now. The payroll database sits on an isolated Docker network neither the tunnel daemon nor any sibling container can reach. Agent sessions across machines coordinate through sigilo, a self-hosted IRC rendezvous authenticated by a pinned TLS fingerprint rather than a CA — regenerate the cert and the client refuses to speak until a human updates the pin — with channel content always treated as data, never as instructions. The ops panels are read-only and bound to loopback, reached over an SSH tunnel instead of a homemade login. The architecture is published as a live, clickable diagram at the address above.

Five collectors that settle a circulating claim with my own numbers

Each one exists because something was being repeated as fact and the honest way to settle it was to measure it. rezago tests a viral thread's "~2.7 second repricing window" by timing Polymarket's CLOB against Binance spot, and reports the edge net of taker fees at the book's real depth. brecha tests "send USDC to Arbitrum and you get more" by quoting executable swaps — not index prices — across seven chains at three sizes, and counting how many opportunities survive every cost. cazadores tests "follow the wallets with 80%+ win rates" by computing those rates myself over resolved trades, with the size of the rare losses kept in view, and produces a calibration curve as a by-product: does a share bought at 80¢ actually win 80% of the time? timon is a small control plane that knows each project's closing criterion, checks it against real data, and opens a gate when one is met — a decision only the human takes, served with its evidence. They share one rule that shaped the whole design: they measure, they never execute — no signing, no funds moved, no API key, and they listen on no port at all. Findings land in a vault where dated, sourced state outranks every other note, and every signal carries an expiry so nothing that already closed can be displayed as an opportunity.

Released into the public domain, with a conformance suite that lets anyone check their own implementation

A minimal format for making an agent's output checkable by a third party without trusting whoever issued it and without reaching its server. Signing alone was not enough: a signed document proves who said it, not that it is right — without knowing which rules produced it and from when, a valid signature is just an opinion with a seal. The spec has a frozen canonicalization, published test vectors, an implementer's guide and an explicit section on what a signature does not assert. Ruby, Node and the browser produce byte-identical signatures; the real validation came when another team wrote a fourth implementation in Python from the spec alone and reached identical bytes without ever seeing my code. Their one point of friction — Windows stdin decoding as cp1252 — was paid the same day as a documented toll.

Multi-tenant gym-management SaaS — one codebase, one subdomain per gym

Rails 8.1 monolith on Ruby 4.0: memberships and access control, biometric progress tracking, a nutrition calculator, and training plans generated by a multi-provider AI adapter (Gemini by default, Claude as an alternative) running as background jobs. Server-rendered with Hotwire and Tailwind — no JavaScript build. Solid Queue, Solid Cache and Solid Cable all run on Postgres, so there is no Redis to operate. Native Rails 8 authentication plus Google OAuth, authorization by role with Pundit, tenant scoping in the request cycle, and zero-downtime deploys with Kamal 2.

Two smaller products, both shipped and in use

• Resplandor POS — touch point-of-sale for a Medellín restaurant: table management, invoicing and daily close, with multi-device realtime sync and Google sign-in. Alpine.js and Tailwind over Supabase (Postgres, Realtime, Auth). The design document is written against what actually ships, not the original plan: backend and authentication were explicitly out of scope in v1.0 and had to be added once several devices were in play at once.
• Simulador de Abonos a Capital — loan_calculator.ynt.codes — a mortgage prepayment simulator that projects one-off and recurring extra principal payments against the base schedule, under either reduce-the-term or reduce-the-payment, with a full amortization table. React 19, Vite, Recharts, containerized behind nginx.