Hygo Studio is Hiring: Principal Engineer / Technical Executive

Hygo Studio is hiring a Principal Engineer / Technical Executive — the role description starts with “Focus: Everything.” This is the rare full-stack breadth role where one person ships across UI, backend, AI pipelines, infrastructure, and payment systems. This page documents the role and why AIEH recommends candidates take the complete catalog as the assessment bundle.

This is a real, open role at Hygo Studio (April 2026 listing). Apply at hygo.com/#careers, or take the AIEH bundle below and share your Skills Passport URL alongside your application.

What Hygo is looking for

From Hygo’s job description (verbatim):

We’re not looking for someone who “leads from the whiteboard.” We need a builder — someone who can mass-produce features from the UI layer down to the database, stand up infrastructure on a Friday night, prototype an AI pipeline on Monday, and refactor the billing system by Wednesday. You have the architectural judgment of a CTO and the output of a senior IC who still loves writing code.

Required skills (from the JD):

• 8+ years software engineering with a track record of personally writing code that runs in production
• True full-stack mastery: production UIs (React/Next.js), production APIs (Node.js/NestJS), production databases (PostgreSQL), production infrastructure (Linux servers, systemd, networking)
• Serious AI/ML chops: integrated AI models into production, understands inference pipelines, can evaluate frontier models for production-readiness
• Personally built systems that handle real money — payment processing, subscription management, financial reconciliation
• Deep infrastructure instincts: can diagnose production outages from logs and metrics (connection pool exhaustion, queue backpressure, memory leaks, disk I/O stalls)
• Designed and built systems that scaled through significant growth
• Strong opinions on system design, loosely held
• “You move fast. You’re not afraid of large surface area — you see a problem across three layers and fix all three in one pass.”
• Bonus: Temporal, self-hosted infrastructure, creator/media platforms, crypto payments

Tech stack (the JD lists “all of it”): React 18, Next.js 14, TypeScript, Tailwind, NestJS 11, Prisma, PostgreSQL 18, Redis 7, Temporal, Docker, Linux/systemd, DigitalOcean, Cloudflare R2, Python/PyTorch, Authorize.net, Sentry, OpenTelemetry, GitHub Actions, Playwright, Storybook.

How AIEH maps this role to a Skills Passport bundle

This is the only role at Hygo where AIEH recommends the complete catalog. The JD is explicit that depth is required across every dimension AIEH measures — there is no specialization here.

Family	Relevance	Why it matters here
JavaScript Fundamentals	0.85	Full-stack JS/TS depth from UI to backend.
Python Fundamentals	0.75	”Python/PyTorch (AI pipelines)” is in the explicit tech list.
AI Output Evaluation	0.80	”Evaluate whether a frontier model is ready for your use case or needs fine-tuning.”
ACL (Prompt-to-Spec)	0.75	The JD demands AI integration from research to production — translating spec to working AI pipeline is core ACL territory.
Cognitive Reasoning	0.85	Diagnosing production outages from logs and metrics is pure reasoning under partial information. The JD explicitly screens for this.
Big Five Personality	0.70	High Conscientiousness for production-reliability work; high Openness for “follows the AI space obsessively.”
Communication	0.65	”Mentor and unblock other engineers across every layer.”
Situational Judgment	0.70	”Strong opinions on system design, loosely held” + “knows when to take on tech debt vs. pay it down” are pure SJT territory.

Pillar weights for this role

For this role we use AIEH’s default weights — no adjustment — because the JD demands balance, not specialization:

• Cognitive: 0.25 — production diagnosis + architectural decisions
• Domain: 0.35 — full-stack + AI + payments + infra depth
• AI fluency: 0.25 — AI integration is core to the role
• Communication: 0.15 — mentorship + opinion-articulation matter, but not the primary screen at this seniority

The composite score on the 300-850 calibrated scale for this role should land in the upper quartile across all four pillars — a candidate who scores 800 in domain but 500 in cognitive reasoning is not the right fit. The JD’s “no waiting for specialists — you become the specialist” line means this role rewards balanced strength, not peaked depth.

Two ways to apply

Apply directly: visit hygo.com/#careers and follow Hygo’s application flow.

Apply with an AIEH Skills Passport: start with whichever AIEH families are currently live (Big Five and JavaScript Fundamentals at time of writing). Complete the rest as they flip to active. Share your passport URL alongside your hygo.com application — given this role’s breadth, the balanced-pillar profile from a complete passport is exactly the signal Hygo is screening for.

What AIEH cannot test (Hygo screens directly)

• 8+ years shipping production systems personally — résumé + reference evidence. The JD is explicit: “not managing from a distance, but personally writing the code that runs in production.”
• Production payment systems you’ve built — covered in the Hygo Payment Engineer role too; bring the same evidence (tokenization, reconciliation, refunds, chargebacks, end-to-end ownership).
• Production AI integration — frontier model evaluations you’ve done, inference pipelines you’ve built, fine-tuning or prompting work you’ve shipped. Show the dashboards.
• Self-hosted infrastructure operation — DigitalOcean, Linux/systemd, on-call experience. The JD calls out “comfortable SSHing into a box at 2 AM.” Show incidents you’ve personally resolved.
• Architectural judgment from real scale — “you watched the dashboards while real traffic hit your code.” Reference + portfolio question.

The JD also asks all applicants for: example links to live production work owned end-to-end, rough traffic/usage metrics, and an estimate of how much LLM/coding-agent contribution went into those examples. For Principal candidates, the LLM/agent percentage matters more than for other roles — Hygo wants someone who has strong opinions about where AI accelerates shipping and where it creates technical debt.

Related roles at Hygo

The Principal scope overlaps every other Hygo role. If you’re considering this role, you should also be able to credibly fill any of:

• Hygo Full-Stack Product Engineer — UI/brand/design depth
• Hygo Payment & Billing Engineer — financial systems depth
• Hygo AI Engineer — Classifiers, Voice R&D — ML/Python depth

If you can only do one of these, the Principal role is not the right fit — apply for the specialist role instead.

Related AIEH guides

• How AIEH scores work — the 300-850 scale and 4 pillars
• What is the Skills Passport
• Generic Engineering Manager career guide (different role — leadership-from-distance vs the IC-builder Principal role Hygo is hiring)