A reproducible lab for a quiet PostgreSQL CDC failure that filled a disk while Debezium reported healthy.
Paired disk-fill experiments and isolated heartbeat trials show why a published-table heartbeat advances the replication slot when a timer alone does not. The failure and fix reproduced in two runs each.
EvidencePaired disk-fill runs, repeated heartbeat trials, CSV measurements, and design decisions
Academic operations software for two campuses and more than 2,000 students and staff.
A production rewrite that preserved populated data, kept rollback possible, and separated permanent student identity from academic-session enrolment.
EvidenceMigration, authorization, and production workflows
Casual football stats, clear leaderboards, and proper receipts for the group chat.
Pick who showed up, log the goals and assists, then send one receipt the whole group understands. No player accounts and no league-admin ceremony.
EvidenceLive product, public groups, and shareable receipts
A virtual queue platform with a calmer interface for organizers and attendees.
The redesign pairs a focused queue workspace with a staged platform migration: a React PWA on Vercel, a Next.js API, durable PostgreSQL state, and individually revocable sessions for anonymous attendees.
EvidenceLive product, public source, migration notes, and contract tests
A local-first inspector for copied configuration, credentials, and connection strings.
It catches invisible Unicode, malformed structure, suspicious secret characters, and provider-specific mistakes without sending the input anywhere.
EvidenceZero-runtime-dependency library, privacy tests, and local OCR
An open challenge that turned live DSV shipment data into dependable tools for AI agents.
The server gives MCP clients a small, typed tool surface over DSV tracking while handling an awkward upstream: browser-based bot protection, ambiguous reference formats, incomplete fields, and operational data that still needs a stable contract.
EvidencePublic source, fixtures, ADRs, and live verification