reduce

Extract

From the conversation/context/user:

• The text as it stands — the rule, doc, prompt, or answer to be reduced.
• What it must cover — the cases, points, or duties it exists for: stated in the context, or recovered by you from it.

Gate

Proceed only when: the text is already written, what it must cover is in hand, and the set is closed — nothing unseen is coming.

Anything else, say which in one plain line — never reduce anyway:

• Nothing is written yet → there is nothing to reduce.
• What it must cover can't be stated or recovered → every cut is blind — no way to say what a shorter version must keep doing.
• Something unseen will meet it — a real case shows a class no rule yet decides, or the rule decides only the cases it came from → use widen skill.

Derive

Do not trim the text. Deleting sentences keeps whichever ones were already there — not the shortest way to cover the set. Set the old wording aside, take what it must cover, and derive the shortest statement that covers all of it.

If what it must cover has moved since the text was written — cases now in hand it never faced, an objective it never served — the old wording is void twice over: derive from the coverage as it stands today, and what comes out is a new derivation of the current set, never the old statement refit to it.

Between candidate statements, prefer the shortest one that covers everything over the one that keeps the original's shape.

The whole run — derivation, shortening, recovery — happens inside this turn; the first thing handed back is the finished result.

Shorten

Push the derived statement shorter, pass by pass. When a pass makes it stop covering something, it went too far — back off by the minimum that recovers it. The overshoot is how you find the floor; what ships covers everything.

The passes end at the floor: every remaining cut costs coverage, and its minimal back-off restores the words that were there. A clause that survives every pass is load-bearing, not fat.