added version number, fixed infinite update loop

src/updater.rs

@@ -154,6 +154,37 @@ pub async fn download_and_apply(
     Ok(current_exe)
 }
 
+// ── Update-target file ───────────────────────────────────────────────────────
+// Written just before exec. On next startup we compare the expected version
+// with CARGO_PKG_VERSION. A mismatch means the replacement didn't work
+// (wrong asset, failed rename, etc.) and we show an error instead of looping.
+
+fn update_target_path() -> std::path::PathBuf {
+    crate::config::config_path()
+        .parent()
+        .expect("config dir has parent")
+        .join(".update_target")
+}
+
+/// Write the expected version to disk before exec'ing the new binary.
+pub fn write_update_target(new_version: &str) {
+    let _ = std::fs::write(update_target_path(), new_version);
+}
+
+/// Read and delete the update-target file.
+/// Returns `Some(expected_version)` if a previous run attempted an update.
+/// The caller should compare it with `env!("CARGO_PKG_VERSION")` and show
+/// an error if they differ.
+pub fn take_update_target() -> Option<String> {
+    let path = update_target_path();
+    if !path.exists() {
+        return None;
+    }
+    let version = std::fs::read_to_string(&path).ok()?;
+    let _ = std::fs::remove_file(&path);
+    Some(version.trim().to_string())
+}
+
 /// Replaces current process via execv (Unix). Never returns on success.
 /// `exe_path` must be the path captured *before* the binary was replaced —
 /// do NOT call std::env::current_exe() here, it returns "(deleted)" on Linux.