test: deepen and complete project-wide test coverage (#297)

* test: deepen coverage for health doctor provider and tunnels

* test: add broad trait and module re-export coverage

src/config/mod.rs

@@ -9,3 +9,45 @@ pub use schema::{
     SandboxBackend, SandboxConfig, SecretsConfig, SecurityConfig, SlackConfig, TelegramConfig,
     TunnelConfig, WebhookConfig,
 };
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn reexported_config_default_is_constructible() {
+        let config = Config::default();
+
+        assert!(config.default_provider.is_some());
+        assert!(config.default_model.is_some());
+        assert!(config.default_temperature > 0.0);
+    }
+
+    #[test]
+    fn reexported_channel_configs_are_constructible() {
+        let telegram = TelegramConfig {
+            bot_token: "token".into(),
+            allowed_users: vec!["alice".into()],
+        };
+
+        let discord = DiscordConfig {
+            bot_token: "token".into(),
+            guild_id: Some("123".into()),
+            allowed_users: vec![],
+            listen_to_bots: false,
+        };
+
+        let lark = LarkConfig {
+            app_id: "app-id".into(),
+            app_secret: "app-secret".into(),
+            encrypt_key: None,
+            verification_token: None,
+            allowed_users: vec![],
+            use_feishu: false,
+        };
+
+        assert_eq!(telegram.allowed_users.len(), 1);
+        assert_eq!(discord.guild_id.as_deref(), Some("123"));
+        assert_eq!(lark.app_id, "app-id");
+    }
+}