content-source-routerlisted

# Content Source Router ## Coverage - File-extension dispatch — `.md` routes to the markdown source, `.mdx` routes to the MDX source, no extension or `.cms.json` routes to the CMS source - Content-path prefix dispatch — `content/posts/**` routes to local sources; `content/cms-synced/**` routes to the CMS source even if the file extension is `.md` - Explicit source hints — internal callers (preview tools, manual reconciliation) pass an explicit `source` parameter that bypasses inspection - Coverage-gap surfacing — when no detection rule matches a request, the router returns a structured "unknown source" result; it never silently picks a default - Adding a new source — the workflow for landing a fourth source (Notion API, Sanity, etc.) without breaking the existing three (registration, routing precedence, fixture test, end-to-end content-fetch sanity) ## Philosophy A content router is a dispatch surface that has to be exactly right or the rest of the site reads the wrong content. Every misroute is either a 404 (the user sees nothing) or a wrong-content render (the user sees a different post than the URL implies). The discipline is the same anti-default doctrine the `skill-router` applies to skills: prefer an explicit signal over an inferred one, prefer an unambiguous match over a "best guess," and prefer surfacing a coverage gap loudly over silently routing to a default. ## Routing Rules The router evaluates four signals in priority order. The first signal that produces a