[NickAkhmetov]

Summary

• Show a 504 Gateway Timeout page for upstream API timeouts, and 502/503 pages for unreachable/unavailable APIs.
• Reuse connections to search, entity, and assets APIs to prevent indefinite hanging requests.
• Add titles for the new 502 and 503 error pages, which otherwise rendered as "Unexpected Error".
• Bump portal-visualization[full] to >=0.5.14, which adds the shared session and request timeouts this branch depends on.

Design Documentation/Original Tickets

N/A

Testing

Added unit tests, adjusted mocks so that requests are properly scoped by session

Screenshots/Video

Include screenshots or video demonstrating any significant visual or behavioral changes.

Checklist

• Code follows the project's coding standards
  • Lint checks pass locally
  • New CHANGELOG-your-feature-name-here.md is present in the root directory, describing the change(s) in full sentences.
• Unit tests covering the new feature have been added
• All existing tests pass
• Any relevant documentation in JIRA/Confluence has been updated to reflect the new feature
• Any new functionalities have appropriate analytics functionalities added

Additional Notes

Depends on x-atlas-consortia/portal-visualization#157, released as portal-visualization 0.5.14.

🤖 Generated with Claude Code

[john-conroy]

Do we need to update the error pages?

[NickAkhmetov]

@john-conroy Yes, good catch. The new 502 and 503 handlers render the React error page, but its title map in pages/Error/utils.ts stopped at 504, so those pages showed "Unexpected Error". 9d78e8d adds "Bad Gateway" and "Service Unavailable" titles. The body text falls through to the generic "If this problem persists, submit a bug report", which fits transient upstream failures, so I left ErrorBody unchanged.

[john-conroy]

Thanks for addressing my previous comments.

Not directly impacted by this PR, but _get_sitemap_entities_cached and _get_publication_data_types_and_organs will cache an errored result. Both catch the exception and return an empty value ([] and ([], [])), and @cache (functools.cache) stores that like a normal result.

[NickAkhmetov]

Good catch. This is fixed in #4107: _get_sitemap_entities_cached and _get_publication_data_types_and_organs now raise instead of returning an empty value, and their callers catch, so a failure is never memoized. The sitemap one is now an lru_cache keyed on the hour bucket, behind a try/except wrapper (_get_sitemap_entities). The template-keys lookup got the same treatment. All three also fetch with use_groups_token=False, since the results are shared across visitors.