# What does this PR do?
Adds supplementary static content to root API spec pages. This is useful for giving context behind a specific API group, adding information on supported features or work in progress, etc.
This PR introduces supplementary information for Agents (experimental, deprecated) and Responses (stable) APIs.
<!-- Provide a short summary of what this PR does and why. Link to relevant issues if applicable. -->
<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->
## Test Plan
Documentation server renders rich static content for the Agents API group:
<!-- Describe the tests you ran to verify your changes with result summaries. *Provide clear instructions so the plan can be easily re-executed.* -->
# What does this PR do?
First step towards cleaning up the API reference section of the docs.
- Separates API reference into 3 sections: stable (`v1`), experimental (`v1alpha` and `v1beta`), and deprecated (`deprecated=True`)
- Each section is accessible via the dropdown menu and `docs/api-overview`
<img width="1237" height="321" alt="Screenshot 2025-09-30 at 5 47 30 PM" src="https://github.com/user-attachments/assets/fe0e498c-b066-46ed-a48e-4739d3b6724c" />
<img width="860" height="510" alt="Screenshot 2025-09-30 at 5 47 49 PM" src="https://github.com/user-attachments/assets/a92a8d8c-94bf-42d5-9f5b-b47bb2b14f9c" />
- Deprecated APIs: Added styling to the sidebar, and a notice on the endpoint pages
<img width="867" height="428" alt="Screenshot 2025-09-30 at 5 47 43 PM" src="https://github.com/user-attachments/assets/9e6e050d-c782-461b-8084-5ff6496d7bd9" />
Closes#3628
TODO in follow-up PRs:
- Add the ability to annotate API groups with supplementary content (so we can have longer descriptions of complex APIs like Responses)
- Clean up docstrings to show API endpoints (or short semantic titles) in the sidebar
## Test Plan
- Local testing
- Made sure API conformance test still passes
