1:00:11Why The Harness Matters More Than The Model | YC Paper Club
Introduction to Harnesses Harnesses (scaffolding/prompt engineering) are crucial for AI progress, not subpar research. They enable quick adaptation to new domains and problems. Harnesses allow for dynamic adaptation and learning from test-time experience. Evolution of Harnesses V0 Harness: Basic GPT-2 with end-of-sequence loop, top-P sampling, and environment interaction. Context Innovations: Few-shot learning (fshot learners), Chain-of-Thought (predicting logic over more tokens). Tool Use: Tool Formers and WebGPT enabled calling external tools (e.g., Python for calculations). Memory Management: MEG-GPT introduced CRUD operations on context ("memory"). Skills and Chaining: Voyager enabled chaining tools and distilling learned skills into prompts. Self-Reflection/Refinement: ReAct, Self-Refine, and Reflection allowed agents to critique and improve their own outputs, leading to multi-agent collaboration. Recursive Agents: RLMs allowed for recursive agent calls to solve larger problems. Static vs. Self-Improving Harnesses Static Harnesses (V1): Fixed agent specs, system prompts, turn limits, tool/skill lists. These run in a loop with context compilation and action execution. Self-Improving Harnesses: Harnesses that learn and adapt. DSPY: Uses genetic programming to learn optimal system prompts from examples. Darwin Machines: Allow agents to modify their own harness code. Meta Harnesses: Generate other harnesses, a highly meta-concept. Continual Harness: Enables CRUD operations on harness components (memory, skills, prompts) and even online learning (Dagger-style) to update model weights at test time. Prime Agent: A Self-Improving Harness Focuses on a first-principles approach to harness building. Adds persistent state, tools, and compute between the LLM and the world. Organizes agents into a project orchestrator (root session) and sub-agents. Utilizes a hierarchical cache-like context (model weights, active context, dispatch state/ripple). Employs "ripples" for in-RAM computation and garbage collection. Manages memory, skills, sub-agents, and prompts through refinement. Compares favorably to other harnesses on benchmarks like ARC AGI, showing significant performance gains. Emphasizes long-horizon performance and efficient context management. Open Jarvis: On-Device Personal AI Aims to build a personal AI stack entirely on-device, addressing cost, privacy, and energy concerns of cloud-based LLMs. Utilizes local LLMs (e.g., Qwen, Gemma) and inference engines (Ollama, Llama.cpp). Defines primitives: user interfaces, agentic logic, intelligence (LLM), inference engine, tools/memory, and learning. Demonstrates competitive performance with cloud LLMs for personal use cases. Leverages cloud LLMs to optimize local configurations for cost and latency reduction. QM: YC's Open-Source Agent Harness Provides a customizable, cloud-like assistant for YC employees via Slack or web UI. Centralizes agent conversations and sandboxes in PostgreSQL for efficient management. Sandboxes are treated as resources rather than fixed homes for agents. Wires agents to company resources (CLI, API keys) and mimics local development environments. Employs a "grind tool" to set budgets (time/tokens) to prevent agents from giving up early. Addresses agent confusion in social contexts and manages information sharing with a fine-grained permission system. Keeps the harness thin, focusing on core tools for execution, storage, and app publishing.















































