Add a fact-binding rule for technical drafts

[iliesaya]

The skill optimises for compression, and compression is where factual links break. On a draft containing numbers and named entities that failure is invisible: two adjacent paragraphs, each correct and each about a different subject, get merged during tightening, and a measurement belonging to one now explains the other. Nothing is misspelled and no number changed.

This happened to me on a technical email. The merged paragraph attributed a solidification result from one alloy to a solubility figure from a different alloy. It read better than the original and survived several re-readings before an outside reviewer caught it.

Nothing in the skill prevented it. "Keep the user's meaning" guards against adding claims, not against rebinding existing ones. "Protect the specific fact" guards against smoothing a detail into generic language, not against moving it to the wrong subject. And "Keep structure unless it's hurting the piece" sanctions reorganising with only a requirement to say why, not to re-verify. eval.md ran 24 checks and none asked whether the facts survived.

SKILL.md gains a section that switches on for drafts with numbers, units, named entities, attributions or causal claims:

• numbers, units, names and attributions are frozen
• no merging, splitting or reordering across a subject boundary without re-checking each fact against the original
• subject-fact binding verified as a separate pass, read against the original rather than from memory
• qualifiers that state a basis or a condition are protected; the ones that express only reluctance are still fair game
• the synonym-cycling ban must not collapse two terms that denote two different quantities
• if tightening requires knowing whether something is true, stop and ask

It also requires the What changed section to list separately every touched sentence carrying a number or a name, so the writer can re-verify exactly those. Without that list they have to re-check the whole draft, which means they will not.

eval.md gains six matching checks, gated on technical content, ranked above every other check on the page so voice never wins over a broken fact.

[petergyang]

Thanks for documenting the failure case so clearly. The fact-integrity idea is valuable, especially preserving subject-to-fact binding, technical qualifiers, numbers, and names. Could you rebase and reduce this to two or three concise safeguards? The current section and sentence-by-sentence change reporting are too heavy for the core skill.