Source Capabilities

Machine-readable source capability matrix. Public, no auth, no credits.

Returns:

• sources[]: per-source entry with key, title, region, status, capabilities (list of supported categories), aliases_to (if applicable)
• by_capability{}: inverse index for each capability type, listing all sources that support it
• capabilities[]: canonical list of capability category names

Example use cases:

• Customer building a "best book for NBA props" comparison: filter by_capability.props ∩ regions==us
• SDK init: cache the matrix, then locally filter when user picks a market type
• AI agent: answer "which books carry NHL game-line live odds?" in one fetch

sleep_iter_53 #551: emits ETag + supports If-None-Match. Source landscape changes only when we add a new book or flip a status; ETag round-trips work for SDK boot polling.