## What changed
- Add `auto_review.node_repl_policy` to model messages for `node_repl` and `cua_repl` reviews.
- Use the reviewer model's configured policy, falling back to the bundled policy when the field is absent and skipping injection when it is explicitly empty.
- Include the effective policy in Guardian session reuse checks and reject unsafe parent-model fallback transitions that would change it.
## Testing
- Cover catalog, bundled, and explicitly empty policies across Node and CUA review paths.
- Verify that policy changes invalidate cached reviewer sessions and incompatible fallback transitions.
GitOrigin-RevId: 51c0bdfed9b464091b6eb47d91ca5a0990d7a315