[owjs3901]

Summary

Emotion code that the build can't compile now fails with a located build error instead of silently staying at runtime (#682). Emotion's cx also composes known classes in argument order.

• EMO-11 / SC-11: Section.withComponent(make()) on a styled component the file defines is a located error. Section compiles to a plain function, so keeping the call made the module throw when it loaded. other.withComponent(...) on an unknown object is still left alone. The retarget test drops the Kept line, and a new rstest covers the error with the exact message and location. The make() filter in retained_render_assertions::retarget is gone.
• EMO-05: an @emotion/react import with no Devup UI equivalent (ThemeContext, withEmotionCache, a default import, import * as E) is a located error that names the export. Before this it was an eprintln! warning, and @emotion/react stayed a runtime dependency. Type-only imports still pass.
• EMO-16 part 2: @emotion/css/create-instance is a located error while @emotion/css is aliased. This covers every way it can be loaded: import, export … from, export *, require(), import x = require() and import(). The new module_loads helper finds these (the vanilla-extract PR adds the same file).
• EMO-16 part 1: confirmed real. cx(blue, red) came out as "a-b a-a", so stylesheet order decided and blue won. cx now composes its arguments like css() composition when at least one argument is a class css() gave. Class maps are lowered to conditions, so cx(blue, on && red, 'ext', { picked: true }) merges with later wins. A template literal, a computed class-map key, or a class map nested inside an array or condition still uses the old join path.
• Docs: limitations no longer lists withComponent(make()) under "cascade decides" or merge as not compiled, and it lists the new errors. The migration/overview page no longer says the package can always be dropped.

New build errors:

• `withComponent()` cannot use `make()` at build time: …
• `@emotion/react` has no Devup UI equivalent of `ThemeContext` …
• `@emotion/css/create-instance` creates an Emotion instance at runtime …

Refs #689
Refs #690

Test plan

• cargo test -p extractor --lib -- emotion import_alias css_prop styled module_loads cx (3451 passed)
• New snapshots reviewed: emotion_cx_merges_known_styles_in_order, emotion_runtime_imports_are_located_errors. One existing snapshot changed: emotion_cx_takes_class_names, where only the class order inside b differs.
• cargo clippy -p extractor --all-targets -- -D warnings, cargo fmt --all
• CI: full test suite + tarpaulin 100%

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
libs/extractor/src/import_alias_visit.rs	100.00% <100.00%> (ø)
libs/extractor/src/lib.rs	100.00% <100.00%> (ø)
libs/extractor/src/module_loads.rs	100.00% <100.00%> (ø)
libs/extractor/src/visit.rs	100.00% <100.00%> (ø)

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