feat: GuiPresence (chat-service presence backend, gateway route, mod module); restore TODO history

backend/gateway/src/config.rs

@@ -8,6 +8,7 @@ pub struct Config {
     pub accounts_http_url: String,
     pub accounts_grpc_url: String,
     pub configs_http_url: String,
+    pub chat_http_url: String,
     pub site_origin: String,
     /// Directory served read-only under `GET /downloads/*` — today just
     /// `lovisual.jar`, the mod's direct download (see TODO.md «Скачивание»).
@@ -33,6 +34,7 @@ impl Config {
             accounts_http_url: var("ACCOUNTS_HTTP_URL")?,
             accounts_grpc_url: var("ACCOUNTS_GRPC_URL")?,
             configs_http_url: var("CONFIGS_HTTP_URL")?,
+            chat_http_url: var("CHAT_HTTP_URL")?,
             site_origin: var("SITE_ORIGIN")?,
             downloads_dir: std::env::var("DOWNLOADS_DIR").unwrap_or_else(|_| "downloads".into()),
             trust_proxy: std::env::var("TRUST_PROXY").is_ok_and(|v| v == "true"),
@@ -71,6 +73,7 @@ mod tests {
             accounts_http_url: String::new(),
             accounts_grpc_url: String::new(),
             configs_http_url: String::new(),
+            chat_http_url: String::new(),
             site_origin: "http://localhost:5173".into(),
             downloads_dir: "downloads".into(),
             trust_proxy: false,

backend/gateway/src/proxy/forward.rs

@@ -31,6 +31,7 @@ pub struct Upstreams {
     pub client: reqwest::Client,
     pub accounts: String,
     pub configs: String,
+    pub chat: String,
     pub internal_key: HeaderValue,
 }
 
@@ -44,6 +45,7 @@ impl Upstreams {
                 .build()?,
             accounts: cfg.accounts_http_url.trim_end_matches('/').to_owned(),
             configs: cfg.configs_http_url.trim_end_matches('/').to_owned(),
+            chat: cfg.chat_http_url.trim_end_matches('/').to_owned(),
             internal_key: HeaderValue::from_str(&cfg.internal_key)?,
         })
     }
@@ -67,6 +69,7 @@ pub async fn proxy(State(up): State<Arc<Upstreams>>, req: Request) -> Response {
     let base = match target {
         Upstream::Accounts => &up.accounts,
         Upstream::Configs => &up.configs,
+        Upstream::Chat => &up.chat,
     };
     let path_and_query = req.uri().path_and_query().map_or("/", |p| p.as_str());
     let url = format!("{base}{path_and_query}");

backend/gateway/src/proxy/routes.rs

@@ -2,12 +2,14 @@
 pub enum Upstream {
     Accounts,
     Configs,
+    Chat,
 }
 
 pub fn upstream_for(path: &str) -> Option<Upstream> {
     match path.trim_start_matches('/').split('/').next()? {
         "auth" | "device" | "avatars" | "media" | "me" | "users" => Some(Upstream::Accounts),
         "configs" | "showcase" => Some(Upstream::Configs),
+        "presence" => Some(Upstream::Chat),
         _ => None,
     }
 }
@@ -26,6 +28,7 @@ mod tests {
         );
         assert_eq!(upstream_for("/configs/shared/ABC"), Some(Upstream::Configs));
         assert_eq!(upstream_for("/showcase"), Some(Upstream::Configs));
+        assert_eq!(upstream_for("/presence/gui"), Some(Upstream::Chat));
         assert_eq!(upstream_for("/authx"), None);
         assert_eq!(upstream_for("/"), None);
         assert_eq!(upstream_for("/health"), None);

backend/gateway/src/rate_limit/rules.rs

@@ -60,6 +60,8 @@ pub fn rules() -> Vec<Rule> {
         ),
         rule(Method::POST, "/avatars", Quota::per_hour(n(5)), Account),
         rule(Method::GET, "/showcase*", Quota::per_minute(n(60)), Ip),
+        // The mod syncs menu presence about 3 times a second while a menu is open.
+        rule(Method::POST, "/presence/*", Quota::per_second(n(6)), Account),
     ]
 }