## What changed
- Add `async_elastic_budgeting` and `async_elastic_sections` under `[features.guardianv2]`, independently of synchronous budgeting and disabled by default.
- Apply section limits and elastic allocation to new classifier evidence after accounting for setup and retained conversation history. Preserve the configured elastic policy when applying model defaults.
- Keep permission context whole during elastic allocation and record truncation observations when image preparation rejects an image.
## Testing
Add coverage for configuration validation, fixed and elastic conversation budgeting, retained history and cursor preservation, and complete classifier requests that retain evidence beyond the fixed entry limit.
GitOrigin-RevId: 2955f0482f7c3e18325e296fc2ccb6592ffcb73a
