[tiensonqin]

Summary

Fix retained MyGo menu row composition at the menu boundary: nonempty labels grow, canonical tooltip-keys render in a visible trailing slot, checks follow Web placement and conditional gutter semantics, and typed dropdown owners receive a chevron. Empty owned labels add no spacer; custom child content remains mounted while closed dropdown panels remain lazy.

docs/api-migrations.md records the default rendering changes and concrete downstream migration. Generic buttons, mutation validation, schema admission, wire vocabulary, dependency pins, and application-owned menu styling are unchanged. Native OS menus retain their OS-controlled presentation.

Validation

• Full MyGo adapter tests, race tests, vet, and production-tag vet: exit 0 with committed public dependencies and GOWORK=off.
• Linux build and Darwin/arm64 + Windows/amd64 cross-builds: exit 0.
• Compatibility check against public MyGo 43c83de431ec using a temporary modfile: tests, vet and build exit 0; committed pins unchanged.
• opam exec -- dune build @web platform/native/ and core dune runtest test/: exit 0.
• Web npm run check: exit 0 (156 tests); tooling/schema tests: exit 0 (24 tests).
• Gated temporary slot harness: fails on exact 1f44501e because the canonical shortcut is absent, passes after the fix, then deleted; no tests retained or existing assertions changed.
• Formatting and staged/cumulative diff checks: exit 0; exactly two tracked files changed, no generated/dependency artifacts.
• Published module v0.0.0-20261029151342-ba39a5080a18 resolves through proxy.golang.org and sum.golang.org. Its extracted Go module builds, passes production-tag vet and existing menu tests: exit 0.

Additional native SDL runtime suite: exit 1 because this machine has SDL 2.0.20 and cannot resolve SDL_RenderGetWindow. Native compilation passed; this is not an all-native-tests-passed claim.

Full tests run from the extracted Go submodule exit 1: the existing TestAllSupportedKindsRender expects ../../schema/mygo-manifest.json from the complete repository, outside that submodule. The complete repository's tests pass; no test assertions or manifest lookup behavior were changed.

Real production Web/native visual qualification is pending. Start from matched menus containing an owned label, canonical shortcut, selected/unselected rows and empty-label custom content; compare slot alignment, remove the last selection/shortcut, then exercise true submenu open/close and dismissal. Application-specific spacing/background recipes must be validated in the consuming application; headless checks do not establish visual parity.

Link to Devin session: https://app.devin.ai/sessions/8fb8206975da46adad697ea4f962c885
Open in Devin Desktop: https://app.devin.ai/desktop/session/8fb8206975da46adad697ea4f962c885?variant=devin
Requested by: @tiensonqin

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring