good stuff

server-rs/src/routes/telemetry.rs

@@ -0,0 +1,77 @@
+use axum::http::{HeaderMap, StatusCode};
+use axum::response::Json;
+use axum::Extension;
+use metrics::{counter, gauge};
+use serde::Deserialize;
+
+use crate::auth::OptionalUser;
+
+#[derive(Deserialize)]
+pub struct TelemetryPayload {
+    session_seconds: u64,
+    filter_count: u64,
+    /// Sent once on first beacon: the entry page path
+    #[serde(default)]
+    entry_path: Option<String>,
+    /// Sent once on first beacon: the document.referrer domain (or "direct")
+    #[serde(default)]
+    referrer: Option<String>,
+}
+
+pub async fn post_telemetry(
+    Extension(user): Extension<OptionalUser>,
+    headers: HeaderMap,
+    Json(payload): Json<TelemetryPayload>,
+) -> StatusCode {
+    let user_label = match &user.0 {
+        Some(u) => u.email.clone(),
+        None => "anonymous".to_string(),
+    };
+
+    let ua = headers
+        .get("user-agent")
+        .and_then(|v| v.to_str().ok())
+        .unwrap_or("unknown");
+    let browser = parse_browser(ua);
+
+    gauge!("user_session_seconds", "user" => user_label.clone(), "browser" => browser.clone())
+        .set(payload.session_seconds as f64);
+    gauge!("user_active_filters", "user" => user_label, "browser" => browser)
+        .set(payload.filter_count as f64);
+
+    // Entrypoint tracking (sent once per session)
+    if let Some(path) = &payload.entry_path {
+        let referrer = payload.referrer.as_deref().unwrap_or("direct");
+        counter!("entrypoint_total", "path" => normalize_entry_path(path), "referrer" => referrer.to_string())
+            .increment(1);
+    }
+
+    StatusCode::NO_CONTENT
+}
+
+/// Normalize entry paths to prevent cardinality explosion.
+/// Keep known routes, parameterize dynamic segments.
+fn normalize_entry_path(path: &str) -> String {
+    match path {
+        "/" | "/dashboard" | "/pricing" | "/learn" | "/saved" | "/invites" | "/account" => {
+            path.to_string()
+        }
+        p if p.starts_with("/invite/") => "/invite/:code".to_string(),
+        p if p.starts_with("/s/") => "/s/:code".to_string(),
+        _ => "/other".to_string(),
+    }
+}
+
+fn parse_browser(ua: &str) -> String {
+    if ua.contains("Firefox") {
+        "Firefox".into()
+    } else if ua.contains("Edg/") {
+        "Edge".into()
+    } else if ua.contains("Chrome") {
+        "Chrome".into()
+    } else if ua.contains("Safari") {
+        "Safari".into()
+    } else {
+        "Other".into()
+    }
+}