Why AI Agents Drift Off-Task (And the 3-File Fix)

The Problem You set up your AI agent perfectly. A week later, it's ignoring rules you clearly stated. You haven't changed anything. What happened? This is context drift — one of the most common failure modes in production AI agent setups. Why It Happens Every agent runs inside a context window. The further you get from your original instructions, the more diluted they become. Three triggers: Long task chains — after 8 tool calls, your system prompt is 6,000 tokens back Sub-agent hand-offs — you pass the task but not the behavioral constraints Session restarts — cron job reloads agent with outdated instructions The 3-File Fix 1. SOUL.md — Reload It Every Task Put your behavioral rules in a file. Not just a system prompt — a file that gets explicitly re-read. Before doing anything else: 1. Read SOUL.md 2. Read USER.md 3. Then proceed This makes identity reloading an observable step , not an invisible assumption. 2. MEMORY.md — Curated Long-Term Memory Daily log files capture everything.