updated generic adapter

backend/src/fetch/generic.rs

@@ -52,7 +52,26 @@ pub async fn fetch(
 ) -> anyhow::Result<Option<FetchedProduct>> {
     let resp = client.get(raw_url).send().await?;
     if !resp.status().is_success() {
-        anyhow::bail!("product page returned HTTP {}", resp.status());
+        let status = resp.status();
+        // Cloudflare/Akamai bot managers answer 403/503 with an active
+        // challenge a plain HTTP client can't solve (needs a real browser).
+        // Name it so the failure is actionable, not a mystery "403".
+        let challenged = resp
+            .headers()
+            .get("cf-mitigated")
+            .is_some_and(|v| v.to_str().map(|s| s.contains("challenge")).unwrap_or(false))
+            || matches!(status.as_u16(), 403 | 503)
+                && resp
+                    .headers()
+                    .get("server")
+                    .and_then(|v| v.to_str().ok())
+                    .is_some_and(|s| s.eq_ignore_ascii_case("cloudflare"));
+        if challenged {
+            anyhow::bail!(
+                "this shop is behind anti-bot protection (Cloudflare) and can't be price-checked automatically"
+            );
+        }
+        anyhow::bail!("product page returned HTTP {status}");
     }
     let body = resp.text().await?;