Kubai Kevin

Gateway API won't fix your Ingress mess

Gateway API does not fix messy Ingress manifests. It changes who owns routing. Here is when delegation is worth the migration and when to wait.

13 min read · 2 November 2026

Contract testing is not optional

Why end-to-end tests and API versioning miss integration breaks, how consumer-driven contracts close the gap, when they fit, and a 30-minute first step.

15 min read · 18 October 2026

Open banking APIs: the integration traps

Open banking integration failures come from semantic gaps between markets. Here is how consent, idempotency and errors differ, and how to test.

15 min read · 17 October 2026

Retire API versions before they pile up

Most API version graveyards come from shipping versions without a deletion plan. Here is how to make old versions cheap to measure, warn about, and remove.

12 min read · 12 October 2026

Rate limiters: burst vs abuse, two designs

Two rate limiter designs compared: token bucket with concurrency cap versus sliding window with penalty box, plus how to tune and measure each.

15 min read · 11 October 2026

Agent versioning: the contract you forgot

Agents expose tool schemas and output shapes as a public interface. Learn how to version that interface, migrate state, and avoid silent caller breakage.

13 min read · 28 September 2026

Idempotency keys: what they fix, what they don't

How idempotency keys work, where they fail, and the failure modes they don't cover: concurrent retries, key reuse, expiry, and partial failures.

14 min read · 21 September 2026

Mobile money agents: when M-Pesa API fails

Mobile money APIs return pending, then settle asynchronously. Learn to poll, deduplicate callbacks, and reconcile orphaned transactions.

14 min read · 18 September 2026

Stop assuming payment APIs never fail

How to combine AI recommendations with M-Pesa, Paystack and Flutterwave calls so gateway timeouts, rate limits and duplicate charges don't break checkout.

13 min read · 13 September 2026

Rogue Agent API Calls: Stop the Bleeding

Runaway agents rarely crash — they succeed too often. Diagnose unbounded loops, retry storms, and feedback cycles, then add budgets and breakers.

10 min read · 7 September 2026

Currency switch fails in Ghana: one config file to rule…

Mobile money providers put currency codes in different places. Learn a deterministic extraction, validation, and normalization pipeline that stops silent fallbacks.

13 min read · 13 August 2026

Designing APIs for High-Latency Satellite Links

How to keep an API reliable over high-latency satellite links: circuit breakers, retry budgets, failover gateways, and the metrics that show what broke.

14 min read · 10 August 2026

Mobile money agent fees: why your bot keeps failing

USSD session timeouts, not payment errors, break mobile money bots in production. Diagnose the session contract mismatch and fix it with per-request clients.

13 min read · 5 August 2026

Stopping a runaway polling agent from flooding your API

Diagnose and fix runaway agent API calls: bounded retries, capped backoff, idempotency keys, and volume alerts that catch spikes before the bill does.

15 min read · 5 August 2026

Big model API vs fine-tune: the 2026 math

A practical framework for deciding between prompting a large model API and fine-tuning a small model, with instrumentation, failure modes and cost math.

15 min read · 3 July 2026

Serve 4G-as-baseline apps in 2026

Design APIs for 300 ms RTT, packet loss and data caps: payload budgets, stale-while-revalidate caching, adaptive fetch and honest measurement.

14 min read · 3 July 2026

Designing Fintech Backends Around Audit Deadlines

Regulatory audit deadlines change how you should split services. A worked example of transaction boundaries, outbox patterns and WAL-based audit reads.

13 min read · 3 July 2026

M-Pesa Daraja 2.0: your 2026 migration checklist

A practical checklist for migrating an M-Pesa Daraja integration across a breaking API change: auth, idempotency, callbacks, error handling and rollout.

14 min read · 2 July 2026

Bank APIs broke under African 2G

Why aggressive caching and remote idempotency stores fail on flaky 2G/3G links, and how to instrument, measure, and redesign balance endpoints for it.

14 min read · 28 June 2026

NDPR 2026 broke fintech APIs

How regulatory transport rules and intermittent mobile connectivity change fintech API design, with worked latency arithmetic and a concrete measurement plan.

12 min read · 26 June 2026

Regulations forced better APIs: the 2026 fintech

Why payment APIs need durable state machines, explicit retry policies, and status endpoints that survive restarts — and when the old synchronous playbook still works.

13 min read · 20 June 2026

Skip M-Pesa: build one API for 3 African markets

How to serve three African mobile-money markets through one orchestrator plus thin provider adapters, with metrics and reconciliation that hold up.

15 min read · 14 June 2026

Tool calls under load: async batch vs fire-and-forget

Compare async batch and fire-and-forget tool-calling patterns: when each fits, how to instrument latency and queue depth, and how to pick a batch size.

16 min read · 13 June 2026

Build a search system in 2026: semantic, keyword

How to build a hybrid search service with PostgreSQL, pgvector, and Redis: schema, keyword and semantic queries, reranking, caching, and how to measure recall.

13 min read · 10 June 2026

Merge three payment APIs into one system

How to consolidate multiple payment provider integrations behind one gateway: routing, idempotency, webhook normalization, and observability.

15 min read · 10 June 2026

GraphQL vs REST vs tRPC: 2026’s API fight

Compare GraphQL, REST and tRPC on caching, type safety, debugging and cost, plus a scoring framework and failure modes for each.

13 min read · 9 June 2026