Contains NaPTAN data from the Department for Transport, © Crown copyright and database right, licensed under the Open Government Licence v3.0.
I work on data systems where a small change can break a lot of downstream work.
I’m John Mikel Regida, a Lead Data Architect in London and the founding platform architect of Brick Rewards, a UK app that rewards renters for paying rent. I led the team behind Great Britain’s national record of public transport stops. I also build Zeno Mobile Runner, which gives AI coding agents a deterministic mobile test gate.
Contains NaPTAN data from the Department for Transport, © Crown copyright and database right, licensed under the Open Government Licence v3.0.
What I led
Two personal accounts. From January 2023 to January 2026, I technically led the team of 7 to 12 people maintaining Great Britain’s national record of public transport stops. At Brick Rewards, a UK app that rewards renters for paying rent, I am the founding platform architect.
Leading safer change in a national transport dataset
I led two changes. Ingestion moved from one long-running request to event-routed workers. Permanent removal gained cross-dataset checks, explicit confirmation, safe retry, and an audit trail.
- 10xincrease in per-submission file capacity, from one file to ten
- >=75%reduction in manual support effort and processing time for managed removal
- 12+ monthsproduction operation with zero erroneous removals
Keeping a rent-rewards platform safe to change
I am the founding platform architect of Brick Rewards, a UK app that rewards renters for paying rent. This account covers how rent is verified from bank data, how the pipeline stays correct and cheap, and how a change reaches production.
- 94xless BigQuery data scanned per bank-data merge, after bounding it on the partition date
- 0false overdue-rent alerts during a two-day bank-data outage, with 1,634 checks deferred instead of the usual 302
- 24 in 1,000requests on one endpoint were failing at scale-down; traced to tail latency past the drain budget, then cut by halving instance churn and serving reads from a snapshot
What I built independently
These are my own open-source projects, not client work. You can read the code and try the browser demos.
Zeno Mobile Runner
A deterministic mobile test runner for AI coding agents. One Zig binary drives real iOS and Android targets, returns typed pass or fail, and writes replayable evidence with no LLM in the execution path.
- 20 / 20passes in the published 17-step iOS determinism run
- 45identical trace events in every published run
- 6reference client languages over one versioned protocol
Safe data change
I built a reviewable path for schema and metric changes: declare the change, check consumers and policies, validate readiness, then apply it. The code is public.
Read the build Independent implementationGoverned AI
I built a governed AI system in the browser that shows which facts an answer may use and why each fact was accepted or rejected. It also shows the exact tool inputs before a call runs.
Read the buildWriting
A case study I co-wrote for martinfowler.com, and an essay on why permanent removal in a shared dataset needs a workflow.
Using the Strangler Fig with Mobile Apps
A case study in modernising established mobile apps one slice at a time. The Strangler Fig pattern plus modular design cut risk and shorten time-to-value.
The Hardest Operation in a Shared Dataset Is Delete
Adding rows is routine. Removing one permanently — from a national dataset with routes, consumers, and published files depending on it — is where the design either holds or does not.
Experience
More than ten years across data, backend, cloud, web, and mobile software.
Founding Platform Architect
Lead Consultant / Lead Data Architect
Senior Software Engineer
Lead Developer / Architect
IT Professional / CTO
Building a data or AI platform where safe change matters?
I’m open to Senior or Staff software engineer roles in data infrastructure and AI platforms, in London or across Europe. If that matches what your team needs, email me.