A practical series on AI agent systems, covering context, harness design, workflows, and multi-agent collaboration.
Context Engineering is the core concept that replaced Prompt Engineering in 2025: the focus shifted from 'how to ask' to 'what information to provide.' Delivering the right information at the right time into the context window is more effective than upgrading to a stronger model. This post covers the definition, four key strategies, practical techniques, and common failure modes.
The same model produces dramatically different results under different harness designs. Anthropic uses a dual-agent architecture, cross-session state files, and a GAN-inspired generator-evaluator loop to let Claude autonomously complete hours-long software development tasks.
AI engineering has gone through three phases: Prompt Engineering (write better instructions) → Context Engineering (feed the right information) → Harness Engineering (design the entire working environment). Each evolution doesn't replace the previous one — it operates at a higher level of abstraction.
A Harness is more than just an LLM wrapper. Tool Registry manages dynamic tool loading and selection, Guard System establishes a four-layer defense network, and Checkpoint-Resume enables long-running tasks to survive interruptions. These three patterns form the critical infrastructure of production-grade Agent systems.
Top Silicon Valley companies are independently building internal AI coding agents that automate everything from a Slack message to a merged PR. This article deep-dives into architectures from Stripe, Ramp, Coinbase, and Spotify — including their 2026 growth numbers (Stripe 7,000+ PRs/week, Ramp 75% of merged PRs) — then expands to cover Google, Meta, Amazon, Uber, Shopify, PostHog, and more.
Agentic Engineering isn't about making AI write code faster — it's about making software move through the entire delivery pipeline faster, by using multi-agent collaboration to compress cross-team coordination friction.
Agent memory isn't a plugin — it's part of the harness itself. Pick the right memory type, estimate data volume, then decide on the technology. And finally, figure out whether you actually own that memory.
An OpenAI internal team spent 5 months with 3 people and 0 lines of hand-written code, delivering a complete product using Codex. This article distills their core lessons on AGENTS.md design, repo-local knowledge bases, architecture enforcement, and entropy management.