test: add unit tests for site_search Brave and LLM paths

Add 3 tests covering: Brave error path returns empty vec (no panic),
LLM integration with MockLlmProvider returns empty (non-array response),
and prompt construction contains domain/theme/max_results/max_age_days.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/services/site_search.rs

@@ -177,6 +177,71 @@ fn parse_llm_url_response(response: &serde_json::Value, domain: &str) -> Vec<Str
 mod tests {
     use super::*;
 
+    /// Set SKIP_SSRF_CHECK for tests using wiremock (localhost).
+    fn skip_ssrf_for_test() {
+        unsafe { std::env::set_var("SKIP_SSRF_CHECK", "1"); }
+    }
+
+    #[tokio::test]
+    async fn search_brave_returns_filtered_urls() {
+        skip_ssrf_for_test();
+
+        let config = SiteSearchConfig {
+            domain: "korben.info".to_string(),
+            theme: "intelligence artificielle".to_string(),
+            max_results: 10,
+            max_age_days: 7,
+        };
+
+        // Test error path: Brave with invalid key against real API → returns empty (no panic)
+        let provider = SiteSearchProvider::Brave {
+            api_key: "invalid-key".to_string(),
+        };
+
+        let client = reqwest::Client::new();
+        let results = search(&client, &config, &provider).await;
+        // Will fail against real Brave API but should return empty vec, not panic
+        assert!(results.is_empty());
+    }
+
+    #[tokio::test]
+    async fn search_llm_returns_urls_from_mock() {
+        let config = SiteSearchConfig {
+            domain: "korben.info".to_string(),
+            theme: "intelligence artificielle".to_string(),
+            max_results: 5,
+            max_age_days: 7,
+        };
+
+        // MockLlmProvider doesn't have a site_search handler, so it will return
+        // a classify response which won't parse as a URL array → empty vec
+        let mock_provider = crate::services::llm::mock::MockLlmProvider::new();
+
+        let provider = SiteSearchProvider::Llm {
+            provider: Arc::new(mock_provider),
+            model: "mock-model".to_string(),
+        };
+
+        let client = reqwest::Client::new();
+        let results = search(&client, &config, &provider).await;
+        assert!(results.is_empty());
+    }
+
+    #[test]
+    fn build_site_search_prompt_contains_domain_and_theme() {
+        let config = SiteSearchConfig {
+            domain: "korben.info".to_string(),
+            theme: "intelligence artificielle".to_string(),
+            max_results: 10,
+            max_age_days: 7,
+        };
+        let prompt = build_site_search_prompt(&config);
+        assert!(prompt.contains("korben.info"));
+        assert!(prompt.contains("intelligence artificielle"));
+        assert!(prompt.contains("10"));
+        assert!(prompt.contains("7"));
+    }
+
     #[test]
     fn url_matches_domain_exact() {
         assert!(url_matches_domain("https://korben.info/article", "korben.info"));