fix(scripts): make configure.py --help print usage without generating files (#7404)

configure.py did not parse its arguments, so `--help` printed no usage and
ran the bootstrap as a side effect (creating config.yaml, .env and
frontend/.env in a fresh checkout), and any unrecognized flag was silently
ignored the same way. Parse arguments with argparse before touching the
filesystem: --help now prints usage and exits 0, unknown flags exit 2, and
the no-argument invocation used by `make configure` is unchanged.

Extend the regression tests from #7102 with two offline subprocess cases
covering both new behaviors.

Fixes #7382

backend/tests/test_configure_script.py

@@ -64,3 +64,38 @@ def test_configure_preserves_existing_configuration(config_checkout: Path, confi
     assert config_path.read_text(encoding="utf-8") == "existing: true\n"
     assert not (config_checkout / ".env").exists()
     assert not (config_checkout / "frontend" / ".env").exists()
+
+
+def test_configure_help_prints_usage_without_generating_files(config_checkout: Path):
+    result = subprocess.run(
+        [sys.executable, str(config_checkout / "scripts" / "configure.py"), "--help"],
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        check=False,
+        timeout=30,
+    )
+
+    assert result.returncode == 0, result.stderr
+    assert "usage: configure.py" in result.stdout
+    assert "Cross-platform config bootstrap script for DeerFlow." in result.stdout
+    assert not (config_checkout / "config.yaml").exists()
+    assert not (config_checkout / ".env").exists()
+    assert not (config_checkout / "frontend" / ".env").exists()
+
+
+def test_configure_rejects_unknown_flags_without_generating_files(config_checkout: Path):
+    result = subprocess.run(
+        [sys.executable, str(config_checkout / "scripts" / "configure.py"), "--not-a-real-flag"],
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        check=False,
+        timeout=30,
+    )
+
+    assert result.returncode == 2
+    assert "unrecognized arguments" in result.stderr
+    assert not (config_checkout / "config.yaml").exists()
+    assert not (config_checkout / ".env").exists()
+    assert not (config_checkout / "frontend" / ".env").exists()

scripts/configure.py

@@ -3,6 +3,7 @@
 
 from __future__ import annotations
 
+import argparse
 import shutil
 import sys
 from pathlib import Path
@@ -17,7 +18,13 @@ def copy_if_missing(src: Path, dst: Path) -> None:
     shutil.copyfile(src, dst)
 
 
-def main() -> int:
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(
+        prog="configure.py",
+        description="Cross-platform config bootstrap script for DeerFlow.",
+    )
+    parser.parse_args(argv)
+
     project_root = Path(__file__).resolve().parent.parent
 
     existing_config = [