Inside a multiplexed secondary profile scope, `_profile_buzz_extra` read the buzz block only from
`gateway.platforms.buzz`, while the runtime loader (`gateway/config_loader.py::platform_section`,
the same seam that feeds this plugin's `apply_yaml_config_fn`) also resolves a top-level `buzz:`
block and the documented `platforms.buzz` shape. A fully configured secondary profile therefore
failed `check_requirements` closed on every boot ("Platform 'Buzz' requirements not met").
Resolve the section through `platform_section` so the gate sees exactly what the loader sees.
Row L1 (profile-scoped gate reads config), topology T2 (multiplexed secondary profile).
Salvaged from #126060 by @liuhao1024 (authorship kept); the test is trimmed to one A->B->A
invariant across two profile homes. Supersedes #126067 (same mechanism, later).
Co-authored-by: liuhao1024 <sunsky.lau@gmail.com>
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