Drupal Eval Commons companion issue for ai_best_practices
## Purpose
This is a companion pointer to the primary Drupal Eval Commons umbrella filed on `drupal/ai`: see [#3586445](https://git.drupalcode.org/project/ai/-/work_items/3586445).
The umbrella issue is the coordination space for shared eval data across:
- `drupal/ai`
- `ai_eval`
- `ai_agents_test`
- `ai_best_practices`
This companion exists so people following `ai_best_practices` can track the cross-module work from this queue as well.
## Why this project is involved
`ai_best_practices` is directly involved in at least three parts of the proposed structure:
- Layer 3: the in-tree tooling layer (\[#3586440\]) is the orchestration sibling to the registry/storage question on the primary umbrella; it covers how skills, evals, and guidelines get aggregated into and placed inside a Drupal project
- Layer 4: browser / community submission work in \[#3588426\]
- Layer 5: the `drupal_builder` domain bundle
The proposal in the primary umbrella is that Layers 3 (tooling), 4 (browser), and 5 (domain bundle) remain here, while the cross-module coordination happens on `drupal/ai`.
## Scope
This issue is not meant to create a second design discussion.
Substantive discussion should happen on the primary umbrella: [#3586445](https://git.drupalcode.org/project/ai/-/work_items/3586445).
This companion is only for:
- visibility in the `ai_best_practices` queue
- cross-linking from \[#3588426\]
- pointing contributors to the primary coordination thread
## Related local issues
- \[#3586440\] (tooling vision; orchestration sibling to umbrella Layer 3)
- \[#3588426\] (browser / community submission; umbrella Layer 4)
- \[#3588906\] (evals distribution; Layer 4 infrastructure dependency)
issue