## What changed
- Treat batch writes containing only `model`, `model_reasoning_effort`,
`plan_mode_reasoning_effort`, `service_tier`, or `personality` as defaults for
future sessions, even when `reloadUserConfig` is requested.
- Keep runtime config reloads and skill/plugin cache invalidation for other
config changes, and document which settings remain session-static.
- Preserve cached skill listings after session-default writes until a forced
reload, with test coverage for each supported default.
GitOrigin-RevId: 6d988014cf4758ceb9422a11f7c2bd5fc6b9f90a
jif
808d3c2702