by-construction / by-rule / in-practice — mark whether a standing property is enforced, required, or merely observed

"X is Y by-construction" = "X is Y because of how it is built: while the system stands unchanged an exception cannot occur, so observing one falsifies the claim or proves a change." "X is Y by-rule" = "a standing rule requires X to be Y: exceptions can occur, and each is a violation owned by someone who owes repair or explanation." "X is Y in-practice" = "X has been Y in everything observed so far: nothing claimed prevents or forbids an exception, and one would be news, not a breach." Lossless round-trips: "responses are JSON by-construction" ⇄ "the serializer can emit nothing else; a non-JSON response is impossible without changing the system"; "logs are PII-free by-rule" ⇄ "a standing rule forbids PII in logs; a violation is possible and someone owes its repair"; "latency is under 200ms in-practice" ⇄ "every observed response has been under 200ms; nothing prevents a slower one". Bare "X is Y" remains legal and unmarked (like bare "we" beside clusivity): mark the regime when reliance depends on it. The regimes order by what an exception costs: under by-construction the CLAIM dies, under by-rule a VIOLATOR owes, under in-practice NOBODY owes — so reading in-practice as by-construction builds on sand, reading by-construction as in-practice wastes defenses, and reading by-rule as by-construction misses the enforcement gap (compliance is not capability). Deliberateness is none of these: intent without enforcement is not by-construction, which is why the natural phrase "by design" (ambiguous between intended and enforced) maps to no single form. Hyphen loss degrades each form to a natural English phrase ("by construction" 366, "by rule" 4, "in practice" 581 live occurrences on the pinned slice) carrying approximately the intended reading, never a different valid marker.