Fabrion
AI & Machine LearningDirect Ashby career site

ML/AI Research Engineer - Agentic AI Lab (Founding Team)

Location
San Francisco, CA · On-site
Job type
Full-time
Level
Senior
Listed
23 days ago

Skills & highlights for this role

  • HuggingFace Transformers
  • LangChain
  • vector databases
  • reinforcement learning from human feedback

Also useful

  • Neo4j
  • DeepSpeed
  • vLLM
  • knowledge graphs

About the role

  • ML/AI RESEARCH ENGINEER - AGENTIC AI LAB (FOUNDING TEAM)
  • Location: San Francisco Bay Area
  • Type: Full-Time

Compensation

Competitive salary + meaningful equity (founding tier)

Backed by 8VC, we're building a world-class team to tackle one of the industry’s most critical infrastructure problems.

About the Role

We’re designing the future of enterprise AI infrastructure - grounded in agents, retrieval-augmented generation (RAG), knowledge graphs, and multi-tenant governance.

We’re looking for an ML/AI Research Engineer to join our AI Lab and lead the design, training, evaluation, and optimization of agent-native AI models. You'll work at the intersection of LLMs, vector search, graph reasoning, and reinforcement learning - building the intelligence layer that sits on top of our enterprise data fabric.

This isn’t a prompt engineer role. It’s full-cycle ML: from data curation and fine-tuning to evaluation, interpretability, and deployment - with cost-awareness, alignment, and agent coordination all in scope.

Core Responsibilities

  • Fine-tune and evaluate open-source LLMs (e.g. LLaMA 3, Mistral, Falcon, Mixtral) for enterprise use cases with both structured and unstructured data
  • Build and optimize RAG pipelines using LangChain, LangGraph, LlamaIndex, or Dust - integrated with our vector DBs and internal knowledge graph
  • Train agent architectures (ReAct, AutoGPT, BabyAGI, OpenAgents) using enterprise task data
  • Develop embedding-based memory and retrieval chains with token-efficient chunking strategies
  • Create reinforcement learning pipelines to optimize agent behaviors (e.g. RLHF, DPO, PPO)
  • Establish scalable evaluation harnesses for LLM and agent performance, including synthetic evals, trace capture, and explainability tools
  • Contribute to model observability, drift detection, error classification, and alignment
  • Optimize inference latency and GPU resource utilization across cloud and on-prem environments

Desired Experience

Model Training

  • Deep experience fine-tuning open-source LLMs using HuggingFace Transformers, DeepSpeed, vLLM, FSDP, LoRA/QLoRA
  • Worked with both base and instruction-tuned models; familiar with SFT, RLHF, DPO pipelines
  • Comfortable building and maintaining custom training datasets, filters, and eval splits
  • Understand tradeoffs in batch size, token window, optimizer, precision (FP16, bfloat16), and quantization

RAG + Knowledge Graphs

  • Experience building enterprise-grade RAG pipelines integrated with real-time or contextual data
  • Familiar with LangChain, LangGraph, LlamaIndex, and open-source vector DBs (Weaviate, Qdrant, FAISS)
  • Experience grounding models with structured data (SQL, graph, metadata) + unstructured sources
  • Bonus: Worked with Neo4j, Puppygraph, RDF, OWL, or other semantic modeling systems

Agent Intelligence

  • Experience training or customizing agent frameworks with multi-step reasoning and memory
  • Understand common agent loop patterns (e.g. Plan>Act>Reflect), memory recall, and tools
  • Familiar with self-correction, multi-agent communication, and agent ops logging

Optimization

  • Strong background in token cost optimization, chunking strategies, reranking (e.g. Cohere, Jina), compression, and retrieval latency tuning
  • Experience running models under quantized (int4/int8) or multi-GPU settings with inference tuning (vLLM, TGI)

Preferred Tech Stack

  • LLM Training & Inference: HuggingFace Transformers, DeepSpeed, vLLM, FlashAttention, FSDP, LoRA
  • Agent Orchestration: LangChain, LangGraph, ReAct, OpenAgents, LlamaIndex
  • Vector DBs: Weaviate, Qdrant, FAISS, Pinecone, Chroma
  • Graph Knowledge Systems: Neo4j, Puppygraph, RDF, Gremlin, JSON-LD
  • Storage & Access: Iceberg, DuckDB, Postgres, Parquet, Delta Lake
  • Evaluation: OpenLLM Evals, Trulens, Ragas, LangSmith, Weight & Biases
  • Compute: Ray, Kubernetes, TGI, Sagemaker, LambdaLabs, Modal
  • Languages: Python (core), optionally Rust (for inference layers) or JS (for UX experimentation)

Soft Skills & Mindset

  • Startup DNA: resourceful, fast-moving, and capable of working in ambiguity
  • Deep curiosity about agent-based architectures and real-world enterprise complexity
  • Comfortable owning model performance end-to-end: from dataset to deployment
  • Strong instincts around explainability, safety, and continuous improvement
  • Enjoy pair-designing with product and UX to shape capabilities, not just APIs

Why This Role Matters

This role is foundational to our thesis: that agents + enterprise data + knowledge modeling can create intelligent infrastructure for real-world, multi-billion-dollar workflows. Your work won’t be buried in research reports - it will be productionized and activated by hundreds of users and hundreds of thousands of decisions. If this is your dream role - we would love to hear from you.

Read the original posting

From Fabrion's careers page, first listed on Rolev.ai on October 17, 2026. Rolev.ai is not the employer.

How Rolev.ai helps with this application

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Common questions

Where is the ML/AI Research Engineer - Agentic AI Lab (Founding Team) job at Fabrion located?

This ML/AI Research Engineer - Agentic AI Lab (Founding Team) position at Fabrion is located in San Francisco, CA (On-site). Always check Fabrion's application page for specific state eligibility or relocation policies.

What qualifications are required for ML/AI Research Engineer - Agentic AI Lab (Founding Team) at Fabrion?

For the ML/AI Research Engineer - Agentic AI Lab (Founding Team) role, Fabrion highlights experience with HuggingFace Transformers, LangChain, vector databases, reinforcement learning from human feedback. Rolev.ai can score your existing resume against these requirements and show any skill gaps before you apply.

How do I apply for the ML/AI Research Engineer - Agentic AI Lab (Founding Team) position at Fabrion?

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