🐛 Fix silent overwrite of main.py and README.md in current directory mode

src/fastapi_new/new.py

@@ -190,6 +190,24 @@ def new(
         if not current_dir and config.path.exists():
             _exit_with_error(toolkit, f"Directory '{config.name}' already exists.")
 
+        # In current directory mode there is no new directory to protect
+        # existing work, so check the files the template writes. Without
+        # this, running the command in the wrong directory silently
+        # destroys an existing main.py and README.md.
+        if current_dir:
+            existing = [
+                name
+                for name in ("main.py", "README.md")
+                if (config.path / name).exists()
+            ]
+            if existing:
+                _exit_with_error(
+                    toolkit,
+                    "Refusing to overwrite existing file(s): "
+                    + ", ".join(existing)
+                    + ". Move them aside or run in an empty directory.",
+                )
+
         if shutil.which("uv") is None:
             _exit_with_error(
                 toolkit,

tests/test_new.py

@@ -98,6 +98,18 @@ def test_rejects_existing_directory(temp_project_dir: Path) -> None:
     assert "Directory 'existing_project' already exists." in result.output
 
 
+def test_refuses_to_overwrite_existing_files_in_current_dir(
+    temp_project_dir: Path,
+) -> None:
+    (temp_project_dir / "main.py").write_text("precious code")
+    (temp_project_dir / "README.md").write_text("precious readme")
+    result = runner.invoke(app, [])
+    assert result.exit_code == 1
+    assert "Refusing to overwrite" in result.output
+    assert (temp_project_dir / "main.py").read_text() == "precious code"
+    assert (temp_project_dir / "README.md").read_text() == "precious readme"
+
+
 def test_rejects_python_below_3_10(temp_project_dir: Path) -> None:
     result = runner.invoke(app, ["test_project", "--python", "3.9"])
     assert result.exit_code == 1