Salmanap/signals

[salmanap]

This PR adds support for agentic interaction signals that serve as a close and fast proxy of good/bad agentic interactions with users.

In general, to fix this type of issue you should avoid deriving resource URLs (especially ones used in markup-like contexts) from user-controlled request data. Instead, construct such URLs from trusted configuration, or validate and restrict any dynamic components (for example, enforce allowed schemes/hosts).

Here, the cleanest fix without changing functionality is to stop falling back to request.nextUrl.origin when constructing baseUrl. The logo is a static asset (/Logomark.png), so there is no real need to incorporate the request’s origin; it can safely be served relative to the deployment base URL taken from environment variables. We can therefore:

• Compute baseUrl only from NEXT_PUBLIC_APP_URL or VERCEL_URL.
• If neither is set, fall back to a safe relative path rather than using request.nextUrl.origin. For example, set logoUrl to "/Logomark.png" when no trusted base URL is configured.
• Keep the rest of the JSX and logic unchanged.

Concretely, in apps/www/src/app/api/og/[slug]/route.tsx:

• Replace the existing baseUrl computation that uses request.nextUrl.origin with one that uses only environment variables.
• Derive logoUrl conditionally: if baseUrl is defined, use ${baseUrl}/Logomark.png, otherwise just "/Logomark.png".

No new imports or helper functions are required.

---

In general, to fix incomplete URL substring sanitization, you must avoid checking hostnames with generic string operations (includes, indexOf) on the full URL string. Instead, parse the URL using a standard URL parser, extract the hostname (and optionally the protocol/port), and compare against a strict whitelist of allowed hosts. This ensures that the allowed host cannot be smuggled in via the path/query, or as part of another domain name.

For this specific code in apps/www/src/app/blog/[slug]/layout.tsx, we should stop using url.includes("...") on process.env.NEXT_PUBLIC_APP_URL. The best way, without changing the overall behavior, is:

• Parse process.env.NEXT_PUBLIC_APP_URL with the built-in URL class.
• Extract hostname (and possibly protocol) from that parsed object.
• Define an allowedHosts array: ["archgw-tau.vercel.app", "plano.katanemo.com", "localhost"].
• Check whether the parsed hostname is exactly in that list.
• Only if the host is allowed, set baseUrl to the normalized URL string (e.g., urlObj.origin) or to the original env value if we want to preserve scheme and port. For localhost:3000 we should accept localhost with port 3000, so we can additionally check hostname === "localhost" && urlObj.port === "3000" as allowed.
• Wrap parsing in a try/catch so that an invalid URL in the env var does not crash metadata generation; if parsing fails or host is not allowed, we keep the existing default http://localhost:3000.

This change is localized to the if (process.env.NEXT_PUBLIC_APP_URL) block around lines 53–61. No new external dependencies are required; the standard URL class is available in the Node/Next.js runtime. The VERCEL_URL branch is already using strict equality checks on the hostname and does not need modification.