A trap with overly long system prompts

A common reflex when facing unwanted behaviour: add one more rule to the system prompt. It works, up to a point — then some rules start silently contradicting each other, or get ignored with no visible error.

The warning sign: if I can no longer explain from memory, in one sentence, why a rule is there, it’s probably a candidate to be removed or moved into task-specific context rather than the permanent instructions.