Samuel Kaoma

Built the clinical, pharmacy, billing, and onboarding modules of IntelliHealth, a multi-tenant hospital platform on a Go/Echo/PostgreSQL service layer with a React 19 operator front end, working alongside a colleague who owned the tenant-provisioning plane.

Own end-to-end delivery: domain modelling, API contracts, schema migrations, front-end implementation, and production deployment for low-bandwidth institutional users.

Formally attached to the Office Equipment and Maintenance Services Unit at national headquarters.

Rotated through Systems Development, Networking, and Planning while handling sensitive technical data with care.

Implemented the core as a single-writer deterministic state machine — no wall-clock reads, no floating-point money, no order-dependent map iteration — making event-sourced replay byte-reproducible; all three prohibitions are enforced by architecture tests rather than convention.

Delivered an ISO 20022 participant gateway over mTLS with idempotency and signature verification, a multi-tenant React bank portal with in-browser Merkle inclusion and consistency proofs, and a C#/WPF operator console with two-person emergency suspension.

Backed 79 delivered features with a measured 1,059 core tests and 74 portal tests — zero failures, zero skips — plus 280 mutation probes. Each probe edits one production line and requires the suite to fail; surviving probes exposed an entirely untested browser session layer and a gridlock-resolution path that bypassed the settlement check.

Implemented the full speaker-evidence stack from first principles — GMM-UBM by EM, i-vector total-variability extraction, LDA/WCCN, and two-covariance PLDA with the exact closed-form log-likelihood ratio — against NumPy and SciPy alone, with no deep-learning framework required. A borrowed pre-trained extractor sits behind an optional dependency and an architecture boundary, benchmarked against the reference stack rather than replacing it.

Built the DSP front end (MFCC/LFCC, VAD, LPC formant estimation, YIN pitch tracking, jitter/shimmer/HNR), an analysis-by-synthesis CELP narrowband channel model, and an LFCC/GMM spoofing countermeasure with an explicit out-of-domain indicator.

Encoded three guarantees in the type system: absence carries its reason instead of collapsing to LR = 1, a likelihood ratio cannot exist without an explicit justified prior, and uncalibrated scores are unreportable. A build-time check fails if the vocabulary of identification appears in any emittable string.

Extended it through the buy side — sourcing, purchase orders, goods receipt, landed-cost allocation and per-deal margin — over a stock ledger with transaction-scoped, self-rolling-back database tests.

Secured sessions with JWT access tokens plus rotating refresh tokens in httpOnly cookies, pluggable S3-compatible storage, and per-route permission enforcement documented route by route.

Diagnosed a silent-CI class of failure and reproduced it on demand: without DATABASE_URL, 69 of 145 tests skip while all seven packages still report ok and the command exits 0 — precisely the approvals, stock-ledger, landed-cost and payables tests. CI sets the variable, so CI has always run the full suite; it is local runs that quietly do not.

Made provenance a type invariant: a GroundedValue cannot be constructed without a ValueOrigin, so no verdict can rest on an unscaled or unsourced measurement, and a customary boundary cannot support a violation asserted inside its own positional error.

Compiled applicable rules plus a household brief into CP-SAT constraints that each carry the rule that produced them, then re-judged every generated layout with the compliance engine — which caught the solver placing buildings on the very setback they were generated to satisfy.

Designed the orchestration grounding layer so a language model cannot originate a number: tools return registered value references, the facade refuses raw numeric arguments, and a validator rejects any draft containing a numeral the session never obtained.

Built the pharmacy and revenue side: stock receipt and adjustment ledgers, dispensation history, low-stock and expiry alerting, FDA drug lookup, drug-interaction checking, and invoice finalisation into a billing cycle.

Built the tenant onboarding lifecycle on top of a colleague's ControlHub provisioning plane — document submission with timeline tracking, activation emails, admin setup links, and the admin review flow — over middleware-enforced tenant scoping. It is the only module in the codebase carrying its own tests.

Layered RBAC with per-user permission overrides and audit logging on every state change, with a React 19 operator front end over the Go/Echo service layer.

Built as four cooperating services in one repo — a Go/Echo API, a React + Vite dashboard, an Expo mobile app for field workers, and a Python/XGBoost yield-prediction service.

Verifies farm claims against independent, hard-to-fake sources: Sentinel-2 NDVI (Copernicus), the ZNSDI cadastral geoportal, and GPS geofencing — surfaced as a signed, QR-verifiable lender report.

Enforces tenant isolation at two layers — request-scoped middleware plus PostgreSQL Row-Level Security that fails closed — with Go, Vitest, and Python test suites all passing.