E.18.1:4.2 - Positive carry-through: one executable first use

Use the first three rows for an ordinary case. Open the fourth only when the source sentence contains the additional claim. Other relation families use the same branch rule in 4.6; consult the single relation-selection map in Relations only for the relation actually being asserted.

What the reader has	Do now	Result or stop
Accepted `ProblemCard@Context PC-FAB-042`: the cooling-fixture deformation is not one more tuning defect because method comparison must preserve a heat-flow invariant.	Carry that distinction into the question: “Which structure does the proposed mathematical lens preserve, which does it lose, and where does its use stop?”	One recognizable receiving question; no method, declaration, plan, or work claim yet.
That question names one mathematical-lens relation.	In the Relations map, select `C.29` once and apply its Solution to the cooling-fixture subject and comparison use.	`CoolingFixtureHeatFlowLensUse-042`: preserved structure, lost deformation factors, payoff for method comparison, declared use, and stop.
The `C.29` result still carries the accepted heat-flow distinction.	Continue with that value; stop before method comparison until its comparator, candidate set, and measurement basis are current.	A useful positive P2W continuation. No compact note is needed unless another user must replay it.
The same source also shows a `FormalSubstrate` signature.	Split the signature claim from the lens-use claim. Apply `A.6.0` only if its defined subject, ranged value, and selected profile can be named.	A separate declaration result, or a stopped declaration cue. The signature neither replaces the `C.29` result nor selects a method.

This example exercises the ordinary route: one carried distinction, one concrete question, one map lookup, one result from the pattern that answers the question, and one visible stop. A case with several claims splits before any pattern is applied; a case with only a cue stops under 4.6.