Applying a Systems Engineering Framework to Agentic Coding: Why Prompts Fail and Structure Wins

Agentic AI coding tools are transforming how we build software. But they share a fundamental constraint: context windows are finite, and as chat sessions grow, AI performance degrades, a phenomenon Anthropic calls context rot . The model loses its grip on early instructions, leading to a frustrating "fix-it loop" where the agent fixes one thing but breaks another. Most of us prompt an agent, let it write code, review it, and repeat. This works beautifully for prototypes. But when you need to build a stable, full-featured product with hundreds of mission-critical acceptance criteria (AC), "vibe-coding" breaks down. The reality is that you get better behavior from agents the same way you get it from humans, by explicitly capturing what good and bad look like, and checking against it . Coming from a systems engineering background in regulated industries, I knew we needed to stop treating agents like conversational chat buddies and start treating them like engineering assets. That's why I built DevCortex : a purpose-built structured intelligence layer that brings systems engineering discipline to agentic workflows. What is DevCortex? DevCortex is an agentic development platform built on one core idea: AI agents work best when they have structured, queryable access to a database of requirements they can interrogate on demand, not a wall of text in a prompt. It sits between the human specification and AI execution using three components: 1. An Agentic-V Model Database: A structured hierarchy mapping your high-level vision (ConOps) to system specs (Specs), individual requirements (Reqs), linked defects (Issues), and an auto-generated Traceability Matrix. 2. An MCP Server: Delivers just-in-time, high-signal context to tools like Claude Code or Open Code. Instead of dumping requirements upfront, the agent queries exactly what it needs, when it needs it. 3. Human Control Planes (Web UI & CLI): A multi-user Web UI with real-time WebSocket feeds to watch your agent work, plus a