A rule written for an agent sets its path, and the agent still drifts. Evil Martians moved every rule a script can check, such as a ban on raw hex colours, out of the agent's instructions, and had agents log missing components in a gap journal instead of editing shared code. NN/g shows the cost of skipping that discipline: one participant lost 45 minutes after the AI pulled the wrong articles from a folder only it could search. The fix that holds is small. Keep each task precise enough that drift shows, turn a mistake that repeats into a rule, and end every request with a short review step that flags what wandered.
Nielsen Norman GroupThe New Big Ball of Mud: Why Agentic AI Systems Turn FragileIn an NN/g study of non-engineers building agent workflows, Tanner Kohler found five of the patterns Foote and Yoder described in 1997, from untested rules files that become load-bearing to a junk-drawer folder only the AI can search. One participant lost 45 minutes fixing instructions after the AI pulled the wrong articles from such a folder.
Why it matters
The proposed test is short. Could you say which kind of context to change, global, local or ambient? If not, the AI is the sole navigator of your setup. Keep global context brief enough to read in one sitting.
A framework from Evil Martians splits agent work into two workflows, one for building screens and one for changing the design system, so an agent that finds a missing component logs it in a gap journal instead of editing shared code. Rules that can be checked mechanically, such as a ban on raw hex colours, move out of the agent's instructions into scripts and lint rules.
Pattern
Second write-up in a week on design systems written for coding agents, after the AGENTS.md approach on 1 Oct made code the source of truth. This one adds enforcement, because agents drift from rules they only read.
A former global head of brand, who worked on the new identity before leaving at the end of 2025, says the backlash goes deeper than a logo. He argues the fashion-house styling borrows the look of Chanel and Tom Ford without the conditions that made it work for them.
Pattern
Logged here on 24 September as a heritage refresh that kept every recognised symbol, following Instagram's in August. Keeping the symbols has not spared it. The objections land on the luxury styling around them, a part the wordmark-only reading missed.
