Speed up cached devcontainer responses

[thecooltimv-bit]

/claim #24

Summary

This PR speeds up repeated /generate requests for repositories that already have a stored devcontainer result in the database.

Previously, the route checked whether the URL existed in the database, but still fetched repository context before returning the cached result. That meant cached database hits still paid the cost of unnecessary repository-context work.

This change adds an early cached-response fast path before fetching repo context when:

• the URL already exists in the database
• an existing record is available
• regenerate is not requested

It also narrows the Supabase select in check_url_exists() to only the fields needed for the cached response.

Changes

• Return cached database records before calling fetch_repo_context()
• Avoid selecting unnecessary fields from Supabase for the cache check
• Add regression coverage proving repo context is not fetched on cached hits
• Add coverage for the narrowed Supabase select query

Tests

Ran:

py -m pytest tests/test_cached_database_short_circuit.py tests/test_check_url_exists_query.py -q

Result:

2 passed, 1 warning

[thecooltimv-bit]

The targeted regression tests pass locally:

py -m pytest tests/test_cached_database_short_circuit.py tests/test_check_url_exists_query.py -q

Result: 2 passed, 1 warning.

The failing checks appear to be Continuous AI agent errors rather than test failures from this patch. Happy to adjust if there is a specific maintainer-requested change.

[thecooltimv-bit]

The targeted regression tests pass locally:

py -m pytest tests/test_cached_database_short_circuit.py tests/test_check_url_exists_query.py -q

Result: 2 passed, 1 warning.

The failing checks appear to be Continuous AI agent errors rather than test failures from this patch. Happy to adjust if there is a specific maintainer-requested change.