name the layer, not only the primitive

The constitution asks which primitive a feature is. It never asked *where* the
feature belongs, and that let a whole feature get built at the wrong layer.

Four layers, outermost wins: content on disk, engine (facts only the engine can
produce), theme (markup), browser (CSS, then JS). Two rules fall out — the engine
never edits authored text to change how it looks, and a feature needing no engine
fact is not an engine feature. architecture.md carries the table and the test;
CLAUDE.md carries the one-line version, since it is the file always loaded.

The example is named in the docs on purpose. A rule with a scar attached is one an
agent can apply; a rule stated in the abstract gets reasoned around.

HARNESS.md

@@ -52,6 +52,13 @@ must do — not the theme. `verify.sh` fails if the embedded reference theme cha
 changing, because in practice those two drift together — and it fails on a `<script>` tag in that theme,
 because a reference theme that grows taste stops being a reference (ADR-0026).
 
+**The agent names the layer as well as the primitive.** Content on disk, engine, theme, browser — and it builds
+at the outermost layer that can do the job (`CLAUDE.md` §2, `docs/architecture.md`). This exists because a whole
+feature was built at the wrong one: widow prevention as a Markdown transform that inserted a non-breaking space
+into an author's prose. It worked and it had tests; `text-wrap: pretty` does it better with no bytes in the
+content, so the feature was deleted (ADR-0045). If a feature only rearranges how something looks, expect the
+agent to push back toward CSS or a template.
+
 **The core ceiling moved once, on purpose.** `CORE_LOC_MAX` went 2000 → 2800 (ADR-0041) because the original
 figure was costed before any code existed and never budgeted what `cmd/` would hold — `check`, `new`, `-dev`,
 change detection. Treat a *second* raise as evidence that something belongs in `internal/ext/` instead: the