Institut Pasteur de Dakar

What I designed and built

Decisions and trade-offs

Reproducing the legacy HTTP contract exactly

This means inheriting API choices you would not have made yourself, and carrying them into a new architecture. In exchange, the switchover happens route by route, every step is reversible, and no client application across the ten countries had to change. On a health surveillance system, reversibility is worth more than elegance.

Transactional outbox rather than publishing straight to Kafka

One more worker and one more purge to operate, against the guarantee that a broker outage never reaches the field worker. When data entry happens in the field, a failed submission cannot be retried: the person has already left.

In-memory doubles rather than test containers

This imposes design discipline — anything leaving the domain has to go through a port — but the end-to-end suite runs anywhere, with no database, no broker, and no identity provider.

Declaring the sample circuit in the form schema

The alternative, a list of types maintained in the backend, would have preserved exactly the coupling we were trying to remove. The success criterion was that a new form should no longer require a developer.

Writing a custom rendering engine on the field side

Rather than keeping the existing dependency. Roughly 4,400 lines to maintain, against full control of offline behaviour, per-step validation, and prefilling — precisely what real-world use depended on.

Extracting components before duplicating them

Three applications, one versioned and published library: a fix made once benefits all three, and visual drift never sets in.

Fixing a blocked environment in infrastructure-as-code

Bringing it back by hand would have been faster and would have undone itself at the next deployment.

The forms delivered

A forms engine is only worth what it is willing to carry. Four forms went into service, deliberately different in nature.

• SARI — surveillance of severe acute respiratory infections

  A hospital circuit, with specimens attached and passed on to the laboratory and then the biobank.

• CVACi — integrated community alert and surveillance cells

  Community-based surveillance is one of the pillars of health security: it picks up signals where they appear, before they reach a care facility. The circuit has two steps, from a community worker to a health professional who validates, with automatic routing into the validator's queue. A bidirectional bridge links these alerts to the corresponding clinical form, prefilled from the source.

• Maternal and neonatal death notification

  A notification, not a clinical observation: transmission is final, which calls for an exhaustive summary before sending.

• Diphtheria

  Published during the outbreak.

The first three were delivered while the platform was being built. They are what tested the engine's generality: a hospital circuit, a community circuit with two-stage validation, and an irreversible notification have almost nothing in common, and having to fit them into the same abstraction is what shaped the design.