fix: fail-loud on missing evolve/diagnose templates (no silent empty)

tests/unit/test_evolve_prompts_present.py

@@ -23,3 +23,32 @@ def test_evolve_template_present_and_contract(name: str, required_tokens: list[s
     assert text.strip(), f"模板为空: {path}"
     for token in required_tokens:
         assert token in text, f"{name} 缺输出契约关键词 {token!r}（与解析代码不对齐）"
+
+
+def test_video_split_loader_fail_loud_on_missing(tmp_path, monkeypatch):
+    """video_split_cli 的真实 diagnose 加载器缺模板必须 FileNotFoundError。"""
+    monkeypatch.chdir(tmp_path)  # 空目录，无 prompts/*.md
+    from app.harness.video_split_cli import _load_diagnose_prompts
+
+    with pytest.raises(FileNotFoundError, match="缺进化/诊断模板"):
+        _load_diagnose_prompts()
+
+
+def test_runner_evolve_loader_fail_loud_on_missing(tmp_path, monkeypatch):
+    """runner 的真实 evolve 加载器缺模板必须 FileNotFoundError。"""
+    monkeypatch.chdir(tmp_path)
+    from app.harness.runner import Runner
+
+    r = object.__new__(Runner)  # 绕过 __init__，仅测无状态加载器方法
+    with pytest.raises(FileNotFoundError, match="缺进化/诊断模板"):
+        r._load_evolve_prompts()
+
+
+def test_runner_diagnose_loader_fail_loud_on_missing(tmp_path, monkeypatch):
+    """runner 的真实 diagnose 加载器缺模板必须 FileNotFoundError。"""
+    monkeypatch.chdir(tmp_path)
+    from app.harness.runner import Runner
+
+    r = object.__new__(Runner)
+    with pytest.raises(FileNotFoundError, match="缺进化/诊断模板"):
+        r._load_diagnose_prompts()