feat: gate claw runtime selection by availability

android/app/src/test/java/com/hyzq/boss/MasterAgentPromptActivityTest.java

@@ -156,6 +156,43 @@ public class MasterAgentPromptActivityTest {
         assertTrue(viewTreeContainsText(content, "新的当前对话提示词"));
     }
 
+    @Test
+    public void renderPromptProfileShowsClawUnavailableHintWhenBackendCannotBeSelected() throws Exception {
+        TestMasterAgentPromptActivity activity = Robolectric
+                .buildActivity(
+                        TestMasterAgentPromptActivity.class,
+                        new Intent()
+                                .putExtra(MasterAgentPromptActivity.EXTRA_PROJECT_ID, "master-agent")
+                                .putExtra(MasterAgentPromptActivity.EXTRA_PROJECT_NAME, "主 Agent")
+                )
+                .setup()
+                .get();
+
+        JSONObject payload = new JSONObject()
+                .put("promptPolicy", new JSONObject().put("globalPrompt", "全局主提示词"))
+                .put("userPrompt", new JSONObject().put("content", "用户私有主提示词"))
+                .put("projectControls", new JSONObject()
+                        .put("promptOverride", "当前对话提示词")
+                        .put("backendOverride", "claw-runtime"))
+                .put("clawAvailability", new JSONObject()
+                        .put("status", "misconfigured")
+                        .put("selectable", false)
+                        .put("reason", "script_not_found")
+                        .put("reasonLabel", "未检测到有效的 Claw 启动脚本，将自动回退到默认后端。"));
+
+        ReflectionHelpers.callInstanceMethod(
+                activity,
+                "renderPromptProfile",
+                ReflectionHelpers.ClassParameter.from(JSONObject.class, payload)
+        );
+
+        Spinner backendSpinner = ReflectionHelpers.getField(activity, "backendSpinner");
+        assertEquals(1, backendSpinner.getAdapter().getCount());
+        View content = activity.findViewById(R.id.screen_content);
+        assertTrue(viewTreeContainsText(content, "Claw Runtime 当前不可用"));
+        assertTrue(viewTreeContainsText(content, "未检测到有效的 Claw 启动脚本"));
+    }
+
     private static boolean viewTreeContainsText(View root, String expectedText) {
         if (root instanceof TextView) {
             CharSequence text = ((TextView) root).getText();