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Keith J. Hetrick

Engineer of correctness-critical systems: real-time audio DSP and governed context infrastructure for AI agents. A decade in commercial audio before I built tools for it. Solo-shipped Bellweather Studios' first plugin line, plus a governed context-layer backend AI agents consume read-only over MCP.

Experience

Founder & Lead EngineerSeptember 2025 - Present

Bellweather Studios · Remote

  • Architected a cross-surface audio platform over 32 shared C++ modules feeding 8 apps. Native C++20 plugins across VST3, AU, AAX, CLAP, and Standalone, modeled after classic FET, opto, VCA, and vari-mu dynamics. Plus an Electron desktop app and AWS revenue infrastructure. First public release May 2026: signed, notarized, stapled. Bellweather Audio Core shipped as an open-source C++ audio-core library.
  • Built a format-aware release-validation orchestrator. It wraps VST3 (pluginval), AU (auval), CLAP (clap-validator), and AAX (DigiShell / AAX Validator) into canonical proof bundles per release. VST3 and AU qualify through Observatory, an in-house JUCE app, backed by 218 plugin test files.
  • Real-time audio path: lock-free atomics, zero heap allocation, Pimpl-isolated (~99% stack reduction). Each engine clears a 48 kHz / 512-sample block in 30-66 µs, under 1% of the real-time budget. A 7% per-engine regression gate holds it. Sanitizer-backed validation lanes (ASan/UBSan/TSan/RTSan) wired into the build matrix as first-class gates.
  • Stood up a mutation-testing pipeline after a DC-offset bug rode the existing coverage suite clean for months. The pipeline caught it; line coverage didn't.
  • Payment, email, and auth providers decoupled behind Zod-validated adapter boundaries. 107 pre-push gates enforce type strictness, secret hygiene, architecture drift, and reproducibility in ~20s. Escapes caught at the keyboard, not in CI.
Platform EngineerMay 2026 - Present

Confidential consumer-services agency · Remote

  • Architected and shipped a governed context layer. The agency's institutional knowledge (clients, campaigns, brand voice, guardrails, assets) became a Prisma-canonical Postgres system of record. 34 typed models over a single vocabulary, parity-checked against the schema by a commit-time drift gate. Every consumer, human or AI, reads structured operational truth rather than inferring it.
  • Modeled authority as data, not inference. Ownership-scoped RBAC: every state transition is legality-checked, then role-checked. Append-only audit on every mutation. Break-glass cannot express more than a reason-bound, time-ceilinged (≤24h), fully-audited exception. Cross-tenant isolation is proven through the composed adapter; rate limiting fails closed at boot. Governance enforced in code, not asserted in prose.
  • Built REST, CLI, and MCP projections from one credential-less in-process service: no token passthrough, the failure mode the MCP spec forbids. Internal fields are structurally unrepresentable in the projection type. Outputs verified byte-identical across transports under seeded multi-client tests. Held consistent across independent LLM vendors authenticating via OAuth 2.1 + dynamic client registration. In production use by a distributed team.
  • Extended the same governed record into a multi-tenant public-site renderer, now rendering client public sites live. Publishing is a data write, not a deploy. Content is snapshot-frozen and immutable at publish. Custom domains and per-tenant branding derive from the canonical data.
Contract Full-Stack DeveloperAugust 2022 - May 2025

West End Designs · Remote

Shipped an internal employee authentication platform and an AI-powered SEO content generator. Built across Next.js, React, MongoDB, AWS, and Stripe, owning each from data model to deployment.

    Background

    Grammy-nominated; credits with Charlie Wilson, Jennifer Lopez, Boyz II Men, Snoop Dogg, and T.I. over 1B+ cumulative streams and a Billboard #1.