The General row and the preset page already re-read on `settings/changed`, but
the hero chip did not — so changing the default and starting a session without
reloading composed the previous default. That is the one session the setting
claims to govern ("对此后新建的会话生效"), and the chip is what decides it.
A staged pick still wins: `load()` prefers the stage over the refreshed
fallback, so a refresh never overwrites a choice the user just made.
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