Add update check functionality

Implement version checking and update notifications in the GUI

app/src-tauri/src/bridge.rs

@@ -422,6 +422,69 @@ pub async fn health(state: BridgeState<'_>) -> Result<Value, String> {
     data_of(state.request(Cmd::Health).await.map_err(|e| e.to_string())?)
 }
 
+// ---- Update check ----
+
+/// Where the GUI looks for the published app version. Overridable via
+/// SPACESH_UPDATE_URL for local testing against a staging server.
+const DEFAULT_UPDATE_URL: &str = "https://spaceshell.ru/download/latest.json";
+
+#[derive(serde::Serialize)]
+pub struct UpdateInfo {
+    current: String,
+    latest: String,
+    has_update: bool,
+    url: String,
+}
+
+/// Parse a `major.minor.patch` string (tolerating a leading `v` and a
+/// `-prerelease` suffix) into a comparable tuple; missing parts are 0.
+fn parse_ver(v: &str) -> (u64, u64, u64) {
+    let core = v.trim().trim_start_matches('v').split('-').next().unwrap_or("");
+    let mut it = core.split('.').map(|p| p.parse::<u64>().unwrap_or(0));
+    (it.next().unwrap_or(0), it.next().unwrap_or(0), it.next().unwrap_or(0))
+}
+
+/// Fetch the server manifest and compare against the bundled app version.
+/// `current` is the Tauri package version (single source of truth: tauri.conf.json),
+/// which `make dmg` bumps on every build.
+#[tauri::command]
+pub async fn check_update(app: AppHandle) -> Result<UpdateInfo, String> {
+    let current = app.package_info().version.to_string();
+    let manifest_url =
+        std::env::var("SPACESH_UPDATE_URL").ok().filter(|s| !s.is_empty()).unwrap_or_else(|| DEFAULT_UPDATE_URL.to_string());
+
+    let client = reqwest::Client::builder()
+        .timeout(Duration::from_secs(10))
+        .build()
+        .map_err(|e| e.to_string())?;
+    let manifest: Value = client
+        .get(&manifest_url)
+        .send()
+        .await
+        .map_err(|e| e.to_string())?
+        .json()
+        .await
+        .map_err(|e| e.to_string())?;
+
+    let latest = manifest.get("version").and_then(|v| v.as_str()).unwrap_or("").to_string();
+    let url = manifest
+        .get("url")
+        .and_then(|v| v.as_str())
+        .unwrap_or("https://spaceshell.ru/download/spacesh.dmg")
+        .to_string();
+    let has_update = !latest.is_empty() && parse_ver(&latest) > parse_ver(&current);
+
+    Ok(UpdateInfo { current, latest, has_update, url })
+}
+
+/// Open a URL in the default browser (macOS `open`). Used by the update popover's
+/// download action — the GUI itself never streams the .dmg.
+#[tauri::command]
+pub fn open_external(url: String) -> Result<(), String> {
+    std::process::Command::new("open").arg(&url).spawn().map_err(|e| e.to_string())?;
+    Ok(())
+}
+
 // ---- Settings commands ----
 
 #[tauri::command]