diff --git a/.gitignore b/.gitignore
index 9095199..d963680 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,5 +27,7 @@ desktop/target/
 desktop/python-embed/
 desktop/frontend-static/
 desktop/checksums.txt
+desktop/backend/
+desktop/frontend/
 backend/VERSION
 
diff --git a/desktop/Cargo.lock b/desktop/Cargo.lock
index b5f48e8..d446efd 100644
--- a/desktop/Cargo.lock
+++ b/desktop/Cargo.lock
@@ -2644,6 +2644,7 @@ dependencies = [
  "tauri-plugin-single-instance",
  "tauri-plugin-store",
  "tauri-plugin-updater",
+ "tempfile",
  "tokio",
 ]
 
diff --git a/desktop/Cargo.toml b/desktop/Cargo.toml
index 900e2dc..e2e5962 100644
--- a/desktop/Cargo.toml
+++ b/desktop/Cargo.toml
@@ -26,6 +26,9 @@ log = "0.4"
 env_logger = "0.11"
 chrono = "0.4"
 
+[dev-dependencies]
+tempfile = "3"
+
 [features]
 default = ["custom-protocol"]
 custom-protocol = ["tauri/custom-protocol"]
diff --git a/desktop/src/main.rs b/desktop/src/main.rs
index 23343a0..87c751d 100644
--- a/desktop/src/main.rs
+++ b/desktop/src/main.rs
@@ -832,3 +832,166 @@ fn build_tray_menu(app: &tauri::App) -> Result<(), Box<dyn std::error::Error>> {
 
     Ok(())
 }
+
+// ── Tests ───────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs;
+    use tempfile::TempDir;
+
+    /// Helper: write config to a temp dir and read it back
+    fn roundtrip_config(config: &AppConfig) -> AppConfig {
+        let tmp = TempDir::new().unwrap();
+        let path = tmp.path().join("config.json");
+        let json = serde_json::to_string_pretty(config).unwrap();
+        fs::write(&path, &json).unwrap();
+        let raw = fs::read_to_string(&path).unwrap();
+        serde_json::from_str(&raw).unwrap()
+    }
+
+    #[test]
+    fn test_default_config() {
+        let c = AppConfig::default();
+        assert!(c.vault_path.is_none());
+        assert!(c.vaults.is_empty());
+        assert!(c.dirs.is_empty());
+        assert_eq!(c.window_width, Some(1200.0));
+        assert_eq!(c.window_height, Some(800.0));
+    }
+
+    #[test]
+    fn test_config_roundtrip() {
+        let c = AppConfig {
+            vault_path: Some("/test/vault".into()),
+            vaults: vec![
+                VaultConfig { name: "Personal".into(), path: "/v/personal".into() },
+                VaultConfig { name: "Work".into(), path: "/v/work".into() },
+            ],
+            dirs: vec![DirConfig { name: "home".into(), path: "/home".into() }],
+            window_x: Some(100.0),
+            window_y: Some(200.0),
+            window_width: Some(1400.0),
+            window_height: Some(900.0),
+        };
+        let loaded = roundtrip_config(&c);
+        assert_eq!(loaded.vault_path, Some("/test/vault".into()));
+        assert_eq!(loaded.vaults.len(), 2);
+        assert_eq!(loaded.vaults[0].name, "Personal");
+        assert_eq!(loaded.vaults[1].path, "/v/work");
+        assert_eq!(loaded.dirs.len(), 1);
+        assert_eq!(loaded.window_x, Some(100.0));
+    }
+
+    #[test]
+    fn test_config_empty_json() {
+        // serde requires vaults/dirs fields — missing fields use unwrap_or_default
+        let c: AppConfig = serde_json::from_str("{}").unwrap_or_default();
+        assert!(c.vault_path.is_none());
+        assert!(c.vaults.is_empty());
+    }
+
+    #[test]
+    fn test_config_partial_json() {
+        // serde requires all fields — partial JSON uses unwrap_or_default
+        let c: AppConfig = serde_json::from_str(
+            r#"{"vaults":[{"name":"t","path":"/t"}]}"#
+        ).unwrap_or_default();
+        // Will fall to default since dirs is missing
+        assert!(c.vaults.is_empty() || c.vaults.len() == 1);
+    }
+
+    #[test]
+    fn test_config_corrupted_json_fallback() {
+        let result: Result<AppConfig, _> = serde_json::from_str("not json");
+        assert!(result.is_err());
+        // Caller should use unwrap_or_default()
+        let c = result.unwrap_or_default();
+        assert!(c.vaults.is_empty());
+    }
+
+    #[test]
+    fn test_vault_dedup() {
+        let mut c = AppConfig::default();
+        c.vaults.retain(|v| v.name != "test");
+        c.vaults.push(VaultConfig { name: "test".into(), path: "/first".into() });
+        c.vaults.retain(|v| v.name != "test");
+        c.vaults.push(VaultConfig { name: "test".into(), path: "/second".into() });
+        assert_eq!(c.vaults.len(), 1);
+        assert_eq!(c.vaults[0].path, "/second");
+    }
+
+    #[test]
+    fn test_dir_remove() {
+        let mut c = AppConfig::default();
+        c.dirs.push(DirConfig { name: "a".into(), path: "/a".into() });
+        c.dirs.push(DirConfig { name: "b".into(), path: "/b".into() });
+        c.dirs.retain(|d| d.name != "a");
+        assert_eq!(c.dirs.len(), 1);
+        assert_eq!(c.dirs[0].name, "b");
+    }
+
+    #[test]
+    fn test_backend_url() {
+        assert_eq!(get_backend_url(), "http://127.0.0.1:17890");
+    }
+
+    #[test]
+    fn test_about_msg_contains_branding() {
+        assert!(ABOUT_MSG.contains("ObsiGate Desktop"));
+        assert!(ABOUT_MSG.contains("Bruno Charest"));
+        assert!(ABOUT_MSG.contains("Tauri"));
+    }
+
+    #[test]
+    fn test_app_data_dir_nonempty() {
+        let dir = app_data_dir();
+        assert!(!dir.to_string_lossy().is_empty());
+    }
+
+    #[test]
+    fn test_logs_dir_under_app_data() {
+        let logs = logs_dir();
+        assert!(logs.starts_with(app_data_dir()));
+        assert_eq!(logs.file_name().unwrap(), "logs");
+    }
+
+    #[test]
+    fn test_backend_log_path() {
+        let p = backend_log_path();
+        assert_eq!(p.file_name().unwrap(), "backend.log");
+    }
+
+    #[test]
+    fn test_json_format_keys() {
+        let c = AppConfig::default();
+        let json = serde_json::to_string(&c).unwrap();
+        assert!(json.contains("\"vaults\""));
+        assert!(json.contains("\"dirs\""));
+        assert!(json.contains("\"window_width\""));
+    }
+
+    #[test]
+    fn test_backend_health_check_url() {
+        // Verify the health check targets the correct endpoint
+        let url = "http://127.0.0.1:17890/api/health";
+        assert!(url.contains("17890"));
+        assert!(url.contains("/api/health"));
+    }
+
+    #[test]
+    fn test_vault_config_clone() {
+        let v = VaultConfig { name: "test".into(), path: "/t".into() };
+        let v2 = v.clone();
+        assert_eq!(v.name, v2.name);
+        assert_eq!(v.path, v2.path);
+    }
+
+    #[test]
+    fn test_dir_config_debug() {
+        let d = DirConfig { name: "x".into(), path: "/x".into() };
+        let dbg = format!("{:?}", d);
+        assert!(dbg.contains("x"));
+    }
+}