A.19.SOURCE-SET-SPACE-SUBSTRATE:4.12 - Operator kit: choose, declare, self-check, apply governing neighbor

Use this compact kit whenever the task is practical declaration rather than one more explanatory paragraph.

Decision point	What to do now	Admissible result	Stop or apply another pattern when…
`1. What is the line acting on?`	Name `SourceSetFamily`, and when several same-family source sets or set results are live also make the concrete source set recoverable.	The reader can tell which source set or set result the line is about.	The source set still floats behind one vague family word.
`2. Are search and outcome in one declared space or in two?`	Point `SearchSpaceRef` and `OutcomeSpaceRef` to declared `CharacteristicSpace`, then choose `sameDeclaredSpaceAs` or `distinctDeclaredSpaceFrom`.	The space-role split is explicit.	The same-space versus cross-space question is still being guessed from context.
`3. What relation is actually being claimed?`	Write one explicit `SourceToOutcomeRelation` with direction, mode, and carrier.	The reader can inspect what is related to what, through which carrier and relation mode.	You are still leaning on one umbrella word such as `projection`, `portfolio`, or `maps into`.
`4. What qualification is honest?`	Choose the governing `DistortionPosture` token and add one note only when it really sharpens the case.	The line is honest about loss, uncertainty, learning/adaptation, or other qualification.	Qualification remains atmospheric prose or one fake default of transparency.
`5. Which heavier qualifiers are truly active?`	Add only the qualifier fields that the current case actually uses.	Qualifiers stay subordinate to the substrate.	The next question is really interpretive-view work, publication, or policy.

Use this minimal worksheet when drafting or repairing one substrate line:

SourceSetFamily       = ...
SourceSetRef?        = ...
SearchSpaceRef          = ...
OutcomeSpaceRef         = ...
SpaceRefRelationKind    = sameDeclaredSpaceAs | distinctDeclaredSpaceFrom
SourceToOutcomeRelation = <direction, mode, carrier>
DistortionPosture       = <token; optional note>
Optional qualifiers       = <only those actually active>

Run this self-check before you leave the line:

if the worksheet cannot be filled without one hidden assumption, the declaration is not ready yet;
if the next needed prose is mainly “how should the reader inspect this substrate?”, continue in A.19.DECLARED-SUBSTRATE-INTERPRETIVE-VIEW;
if the next needed prose is “what gets published, shipped, retained, or enacted?”, apply G.5, G.10, C.19, or C.24;
if the current line changes because one neighbor wants different naming, glossing, or repair vocabulary, keep the substrate declaration here and let F.18, A.0, or A.6.P handle that neighboring requirement explicitly.