Senior AI Engineer

The role

Own parts of Alpha, an AI agent that reads a customer's account, reasons about their plan and prepares real orders for them to confirm. Work from spec to production, read traces to find failures, and build evals and fixes across the tools, routing, backend and models.

What you will do

• Own parts of Alpha end to end, including how they behave, their quality in production and their long-term health
• Design the harness: tool contracts, context, routing between capabilities and guardrails
• Build observability and evaluation: read traces, categorise failures, fix the most upstream one, and validate LLM judges against human labels
• Run Alpha like a production service: own latency, reliability and cost per conversation
• Engineer deterministic parts such as retrieval, event consumers, planning and money-moving integrations, with idempotency, retries and reconciliation
• Evaluate, fine-tune and serve transformer models for Alpha and other Thndr products
• Answer vague questions with data and recommend between prompting, routing, fine-tuning or a different model
• Write cross-squad proposals and take them from proposal to shipped
• Review other engineers' designs and evals, and help teammates work with coding agents
• Prototype and evaluate AI solutions for other Thndr products and squads, and write up findings

Required qualifications

• Strong software engineering in production, ideally Python with FastAPI, PostgreSQL and queues
• Experience shipping an LLM agent or tool-calling system to real users
• Experience owning the operations of an LLM-backed service: latency, streaming, timeouts, fallbacks, cost and incidents
• Measurement discipline: building evals from real traces
• Hands-on experience with transformers and MLOps, including fine-tuning and evaluating models (SFT or LoRA) and taking them to serving
• Comfortable in SQL and Python analysis, and able to design and defend an experiment
• Ownership across the full stack, including production incidents and monitoring
• Daily fluency with coding agents
• Clear written communication for people outside engineering
• Breadth and speed of learning across more than one kind of problem

Before you apply

• This is an R&D role; most time goes to Alpha, with work on other products and squads as well

About the company

Thndr builds Alpha, an AI agent that prepares customer orders for confirmation. Alpha integrates with Thndr's order, funding, savings and market-data services.