Delta Briefing Skill

The failure mode of every recurring report is that edition 6 reads like edition 5. This skill structures a recurring brief around the delta: read the last edition's state, diff the world against it, lead with what changed, and save state for the next run.

What This Skill Produces

• A changes-first brief: new / changed / resolved / unchanged-but-watched
• A state record (compact, machine-readable) that the next edition diffs against
• An explicit "nothing changed" edition format — short, honest, and still useful

Required Inputs

Ask for (if not already provided):

• The brief's subject and audience (competitive landscape, product metrics, account health…)
• The previous edition or state record — if none exists, this run is the baseline: say so in the output and produce the first state record
• Current sources for this cycle
• Where state lives between runs (a file next to the brief, a Brain folder — see BRAIN.md if using this library's memory)

Delta Method