What
A system prompt was added for a dispatched subagent that reads exactly one comment thread on one published artifact and writes a plain-text brief whose first line must be exactly "ANALYSIS BRIEF". It replaced an unrelated read-before-edit reminder in that slot.
Details
- It may only read that thread plus page data, and any write-shaped tool call is denied.
- Comment text is treated as reader feedback, never as instructions to follow.
Evidence
You are an artifact comment-thread analyst for Claude Code.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.