Add local project indexing and search guidance

app/src/ai/runtime/rig_request.rs

@@ -917,13 +917,19 @@ fn build_system_prompt(
                 .join(", "),
         );
         prompt.push_str(".\nNever invent tool names or parameters. Check command exit codes and tool error results before claiming success.\n");
+        let has_search_codebase = tools.iter().any(|tool| tool.name == "search_codebase");
+        if has_search_codebase {
+            prompt.push_str(
+                "For source-code discovery, semantic questions, or finding an unfamiliar implementation, MUST use `search_codebase` first. Never use `grep` to discover or search source code when `search_codebase` is available; reserve `grep` for exact known text in non-code files. Use `file_glob` only to locate filenames and `read_files` for focused follow-up context.\n",
+            );
+        }
         if tools.iter().any(|tool| tool.name == "run_shell_command") {
             let has_file_tools = tools
                 .iter()
                 .any(|tool| matches!(tool.name.as_str(), "file_glob" | "grep" | "read_files"));
             if has_file_tools {
                 prompt.push_str(
-                    "Prefer `file_glob`, `grep`, and `read_files` for file discovery, content search, and file reading when they are available. Reserve `run_shell_command` for operations those specialized tools cannot perform; do not use shell `find`, `grep`, `rg`, `cat`, `head`, or `tail` as substitutes.\n",
+                    "Prefer `file_glob` for filenames and `read_files` for focused content when they are available. Reserve `run_shell_command` for operations specialized tools cannot perform; do not use shell `find`, `grep`, `rg`, `cat`, `head`, or `tail` as substitutes.\n",
                 );
             }
         }

app/src/ai/runtime/rig_request_tests.rs

@@ -154,15 +154,18 @@ fn builds_a_rig_turn_directly_from_galaxy_request_state() {
 }
 
 #[test]
-fn system_prompt_prefers_specialized_file_tools_over_shell_substitutes() {
+fn system_prompt_prioritizes_semantic_code_search_over_regex_search() {
     let mut params = RequestParams::new_for_test();
-    params.input = vec![user_query("Find every Rust file containing ProviderRun")];
+    params.input = vec![user_query(
+        "Find the implementation that handles ProviderRun",
+    )];
 
     let prepared = prepare_rig_turn(
         &config(),
         params,
         vec![
             ToolType::RunShellCommand,
+            ToolType::SearchCodebase,
             ToolType::FileGlob,
             ToolType::Grep,
             ToolType::ReadFiles,
@@ -171,7 +174,11 @@ fn system_prompt_prefers_specialized_file_tools_over_shell_substitutes() {
     );
     let prompt = prepared.request.system_prompt.expect("system prompt");
 
-    assert!(prompt.contains("Prefer `file_glob`, `grep`, and `read_files`"));
+    assert!(prompt.contains("MUST use `search_codebase` first"));
+    assert!(prompt.contains("Never use `grep` to discover or search source code"));
+    assert!(
+        prompt.contains("Prefer `file_glob` for filenames and `read_files` for focused content")
+    );
     assert!(prompt.contains("do not use shell `find`, `grep`, `rg`, `cat`, `head`, or `tail`"));
 }