fix(prompt): make tool taxonomy mode-aware

crates/tui/src/prompts.rs

@@ -511,24 +511,45 @@ const TOOL_TAXONOMY_DISCOVERY: &[&str] = &["grep_files", "file_search"];
 const TOOL_TAXONOMY_GIT: &[&str] = &["git_status", "git_diff"];
 const TOOL_TAXONOMY_VERIFICATION: &[&str] = &["run_tests"];
 
-fn render_core_tool_taxonomy_block() -> String {
-    let core_tools = crate::core::engine::default_active_native_tool_names();
-    format!(
-        "## Core Tool Taxonomy\n\nUse {} for discovery. Use {} for git inspection. Use {} for verification.",
-        render_core_tool_group(TOOL_TAXONOMY_DISCOVERY, core_tools),
-        render_core_tool_group(TOOL_TAXONOMY_GIT, core_tools),
-        render_core_tool_group(TOOL_TAXONOMY_VERIFICATION, core_tools)
-    )
+fn render_core_tool_taxonomy_block(mode: AppMode) -> String {
+    let core_tools = core_taxonomy_tools_for_mode(mode);
+    let mut sentences = Vec::new();
+
+    if let Some(discovery) = render_core_tool_group(TOOL_TAXONOMY_DISCOVERY, &core_tools) {
+        sentences.push(format!("Use {discovery} for discovery."));
+    }
+    if let Some(git) = render_core_tool_group(TOOL_TAXONOMY_GIT, &core_tools) {
+        sentences.push(format!("Use {git} for git inspection."));
+    }
+    if let Some(verification) = render_core_tool_group(TOOL_TAXONOMY_VERIFICATION, &core_tools) {
+        sentences.push(format!("Use {verification} for verification."));
+    }
+
+    debug_assert!(
+        !sentences.is_empty(),
+        "core tool taxonomy has no active tool groups"
+    );
+    format!("## Core Tool Taxonomy\n\n{}", sentences.join(" "))
 }
 
-fn render_core_tool_group(group: &[&str], core_tools: &[&str]) -> String {
-    group
+fn core_taxonomy_tools_for_mode(mode: AppMode) -> Vec<&'static str> {
+    let core_tools = crate::core::engine::default_active_native_tool_names();
+    core_tools
+        .iter()
+        .copied()
+        .filter(|tool| mode != AppMode::Plan || *tool != "run_tests")
+        .collect()
+}
+
+fn render_core_tool_group(group: &[&str], core_tools: &[&str]) -> Option<String> {
+    let rendered = group
         .iter()
         .copied()
         .filter(|tool| core_tools.contains(tool))
         .map(|tool| format!("`{tool}`"))
         .collect::<Vec<_>>()
-        .join("/")
+        .join("/");
+    (!rendered.is_empty()).then_some(rendered)
 }
 
 /// Authority recap block — appended at the end of the system prompt,
@@ -566,7 +587,7 @@ pub fn compose_prompt_with_approval_and_model(
     approval_mode: ApprovalMode,
     model_id: &str,
 ) -> String {
-    let tool_taxonomy = render_core_tool_taxonomy_block();
+    let tool_taxonomy = render_core_tool_taxonomy_block(mode);
     let base_prompt = apply_model_template(BASE_PROMPT.trim(), model_id);
     let parts: [&str; 5] = [
         tool_taxonomy.as_str(),
@@ -1036,13 +1057,41 @@ mod tests {
             ApprovalMode::Suggest,
             "deepseek-v4-pro",
         );
+        let expected_taxonomy = render_core_tool_taxonomy_block(AppMode::Agent);
 
         assert!(
-            prompt.starts_with("## Core Tool Taxonomy\n\nUse `grep_files`/`file_search` for discovery. Use `git_status`/`git_diff` for git inspection. Use `run_tests` for verification."),
+            prompt.starts_with(&expected_taxonomy),
             "composed prompt should start with the compact generated tool taxonomy"
         );
     }
 
+    #[test]
+    fn plan_prompt_taxonomy_omits_run_tests() {
+        let prompt = compose_prompt_with_approval_and_model(
+            AppMode::Plan,
+            Personality::Calm,
+            ApprovalMode::Never,
+            "deepseek-v4-pro",
+        );
+        let expected_taxonomy = render_core_tool_taxonomy_block(AppMode::Plan);
+
+        assert!(
+            prompt.starts_with(&expected_taxonomy),
+            "Plan prompt should start with its mode-specific tool taxonomy"
+        );
+        assert!(
+            expected_taxonomy.contains("for discovery")
+                && expected_taxonomy.contains("for git inspection"),
+            "Plan taxonomy should keep read-only discovery and git guidance"
+        );
+        assert!(
+            !expected_taxonomy.contains("run_tests")
+                && !expected_taxonomy.contains("for verification")
+                && !expected_taxonomy.contains("Use  "),
+            "Plan taxonomy must not advertise unavailable verification tools: {expected_taxonomy:?}"
+        );
+    }
+
     #[test]
     fn core_tool_taxonomy_only_references_default_active_tools() {
         let core_tools = crate::core::engine::default_active_native_tool_names();
@@ -1402,6 +1451,17 @@ mod tests {
             !text.contains("Reforço de Idioma"),
             "English locale must not get a pt-BR closer: {text:?}"
         );
+        assert!(
+            !contains_cjk(BASE_PROMPT),
+            "base prompt must not contain static CJK priming tokens"
+        );
+        for mode in [AppMode::Agent, AppMode::Plan, AppMode::Yolo] {
+            let taxonomy = render_core_tool_taxonomy_block(mode);
+            assert!(
+                !contains_cjk(&taxonomy),
+                "tool taxonomy must not contain static CJK priming tokens: {taxonomy:?}"
+            );
+        }
         // Do not assert on arbitrary CJK in the full system prompt: project
         // context may legitimately contain localized file names, README text,
         // or user-authored instructions. The locale bookend markers above are