diff --git a/src/tools/mod.rs b/src/tools/mod.rs
index 0f7ddc9..7f788a9 100644
--- a/src/tools/mod.rs
+++ b/src/tools/mod.rs
@@ -219,6 +219,25 @@ impl ToolRegistry {
             tools.extend(identity::tool_definitions());
         }
 
+        // Code search (OpenSearch code index)
+        tools.push(Tool::new(
+            "search_code".into(),
+            "Search the code index for functions, types, patterns, or concepts across \
+             the current project and Gitea repositories. Supports keyword and semantic search."
+                .into(),
+            json!({
+                "type": "object",
+                "properties": {
+                    "query": { "type": "string", "description": "Search query (natural language or code pattern)" },
+                    "language": { "type": "string", "description": "Filter by language: rust, typescript, python (optional)" },
+                    "repo": { "type": "string", "description": "Filter by repo name (optional)" },
+                    "semantic": { "type": "boolean", "description": "Use semantic search (optional)" },
+                    "limit": { "type": "integer", "description": "Max results (default 10)" }
+                },
+                "required": ["query"]
+            }),
+        ));
+
         // Web search (SearXNG — free, self-hosted)
         tools.push(web_search::tool_definition());
 
@@ -436,3 +455,123 @@ impl ToolRegistry {
         .await
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_tool_definitions_base() {
+        let tools = ToolRegistry::tool_definitions(false, false);
+        assert!(tools.len() >= 5, "Should have at least 5 base tools");
+
+        let names: Vec<String> = tools.iter().map(|t| t.function.name.clone()).collect();
+        assert!(names.contains(&"search_archive".into()));
+        assert!(names.contains(&"run_script".into()));
+        assert!(names.contains(&"search_web".into()));
+        assert!(names.contains(&"search_code".into()));
+        // No gitea or identity tools when disabled
+        assert!(!names.iter().any(|n| n.starts_with("gitea_")));
+        assert!(!names.iter().any(|n| n.starts_with("identity_")));
+    }
+
+    #[test]
+    fn test_tool_definitions_with_gitea() {
+        let tools = ToolRegistry::tool_definitions(true, false);
+        let names: Vec<String> = tools.iter().map(|t| t.function.name.clone()).collect();
+        assert!(names.iter().any(|n| n.starts_with("gitea_")), "Should have gitea tools");
+        assert!(!names.iter().any(|n| n.starts_with("identity_")));
+    }
+
+    #[test]
+    fn test_tool_definitions_with_kratos() {
+        let tools = ToolRegistry::tool_definitions(false, true);
+        let names: Vec<String> = tools.iter().map(|t| t.function.name.clone()).collect();
+        assert!(names.iter().any(|n| n.starts_with("identity_")), "Should have identity tools");
+        assert!(!names.iter().any(|n| n.starts_with("gitea_")));
+    }
+
+    #[test]
+    fn test_tool_definitions_all_enabled() {
+        let tools = ToolRegistry::tool_definitions(true, true);
+        let names: Vec<String> = tools.iter().map(|t| t.function.name.clone()).collect();
+        assert!(names.iter().any(|n| n.starts_with("gitea_")));
+        assert!(names.iter().any(|n| n.starts_with("identity_")));
+    }
+
+    #[test]
+    fn test_agent_tool_definitions() {
+        let tools = ToolRegistry::agent_tool_definitions(false, false);
+        assert!(!tools.is_empty(), "Should have agent tools");
+    }
+
+    #[test]
+    fn test_minimal_registry() {
+        let config = Arc::new(crate::config::Config::from_str(r#"
+            [matrix]
+            homeserver_url = "http://localhost:8008"
+            user_id = "@test:localhost"
+            state_store_path = "/tmp/test"
+            db_path = ":memory:"
+            [opensearch]
+            url = "http://localhost:9200"
+            index = "test"
+            [mistral]
+            [behavior]
+        "#).unwrap());
+        let registry = ToolRegistry::new_minimal(config);
+        assert!(!registry.has_gitea());
+        assert!(!registry.has_kratos());
+    }
+
+    #[tokio::test]
+    async fn test_execute_unknown_tool() {
+        let config = Arc::new(crate::config::Config::from_str(r#"
+            [matrix]
+            homeserver_url = "http://localhost:8008"
+            user_id = "@test:localhost"
+            state_store_path = "/tmp/test"
+            db_path = ":memory:"
+            [opensearch]
+            url = "http://localhost:9200"
+            index = "test"
+            [mistral]
+            [behavior]
+        "#).unwrap());
+        let registry = ToolRegistry::new_minimal(config);
+        let ctx = crate::orchestrator::event::ToolContext {
+            user_id: "test".into(),
+            scope_key: "test-room".into(),
+            is_direct: true,
+        };
+        let result = registry.execute_with_context("nonexistent_tool", "{}", &ctx).await;
+        assert!(result.is_err(), "Unknown tool should error");
+    }
+
+    #[tokio::test]
+    async fn test_execute_search_code_without_opensearch() {
+        let config = Arc::new(crate::config::Config::from_str(r#"
+            [matrix]
+            homeserver_url = "http://localhost:8008"
+            user_id = "@test:localhost"
+            state_store_path = "/tmp/test"
+            db_path = ":memory:"
+            [opensearch]
+            url = "http://localhost:9200"
+            index = "test"
+            [mistral]
+            [behavior]
+        "#).unwrap());
+        let registry = ToolRegistry::new_minimal(config);
+        let ctx = crate::context::ResponseContext {
+            matrix_user_id: String::new(),
+            user_id: "test".into(),
+            display_name: None,
+            is_dm: true,
+            is_reply: false,
+            room_id: "test".into(),
+        };
+        let result = registry.execute("search_code", r#"{"query":"test"}"#, &ctx).await;
+        assert!(result.is_err(), "search_code without OpenSearch should error");
+    }
+}