diff --git a/scripts/_entrypoint.py b/scripts/_entrypoint.py
new file mode 100644
index 0000000..36accf1
--- /dev/null
+++ b/scripts/_entrypoint.py
@@ -0,0 +1,13 @@
+"""Bootstrap direct script execution from the repository checkout."""
+
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+
+def add_repository_root_to_path() -> None:
+    """Make project packages importable when a script is run by file path."""
+    repository_root = str(Path(__file__).resolve().parent.parent)
+    if repository_root not in sys.path:
+        sys.path.insert(0, repository_root)
diff --git a/scripts/check_environment.py b/scripts/check_environment.py
index fc33c8a..1fcd222 100644
--- a/scripts/check_environment.py
+++ b/scripts/check_environment.py
@@ -3,7 +3,12 @@
 import sys
 from importlib.metadata import PackageNotFoundError, version
 
-from ingestion.common.environment import (
+if __package__ in {None, ""}:
+    from _entrypoint import add_repository_root_to_path
+
+    add_repository_root_to_path()
+
+from ingestion.common.environment import (  # noqa: E402
     MINIMUM_PYTHON_VERSION,
     is_supported_python,
 )
diff --git a/scripts/check_github_connection.py b/scripts/check_github_connection.py
index 98b6bd7..0996e77 100644
--- a/scripts/check_github_connection.py
+++ b/scripts/check_github_connection.py
@@ -2,10 +2,15 @@
 
 from typing import Any
 
-from ingestion.common.config import ConfigurationError, Settings
-from ingestion.common.logging import configure_logging
-from ingestion.github.client import GitHubClient
-from ingestion.github.exceptions import GitHubAPIError
+if __package__ in {None, ""}:
+    from _entrypoint import add_repository_root_to_path
+
+    add_repository_root_to_path()
+
+from ingestion.common.config import ConfigurationError, Settings  # noqa: E402
+from ingestion.common.logging import configure_logging  # noqa: E402
+from ingestion.github.client import GitHubClient  # noqa: E402
+from ingestion.github.exceptions import GitHubAPIError  # noqa: E402
 
 
 def require_mapping(
diff --git a/tests/test_diagnostic_entrypoints.py b/tests/test_diagnostic_entrypoints.py
new file mode 100644
index 0000000..cf65c73
--- /dev/null
+++ b/tests/test_diagnostic_entrypoints.py
@@ -0,0 +1,70 @@
+"""Regression tests for supported diagnostic invocation forms."""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+REPOSITORY_ROOT = Path(__file__).resolve().parent.parent
+
+
+def run_diagnostic(
+    command: list[str], *, without_token: bool = False
+) -> subprocess.CompletedProcess[str]:
+    """Run a diagnostic from the checkout without inheriting import helpers."""
+    environment = os.environ.copy()
+    environment.pop("PYTHONPATH", None)
+    if without_token:
+        environment["GITHUB_TOKEN"] = ""
+
+    return subprocess.run(
+        [sys.executable, *command],
+        cwd=REPOSITORY_ROOT,
+        env=environment,
+        capture_output=True,
+        text=True,
+        timeout=30,
+        check=False,
+    )
+
+
+@pytest.mark.parametrize(
+    "command",
+    [
+        ["scripts/check_environment.py"],
+        ["-m", "scripts.check_environment"],
+    ],
+    ids=["direct", "module"],
+)
+def test_environment_diagnostic_supports_both_invocation_forms(
+    command: list[str],
+) -> None:
+    """The environment diagnostic must run both directly and as a module."""
+    result = run_diagnostic(command)
+
+    assert result.returncode == 0, result.stderr
+    assert "[SUCCESS] The development environment is ready." in result.stdout
+
+
+@pytest.mark.parametrize(
+    "command",
+    [
+        ["scripts/check_github_connection.py"],
+        ["-m", "scripts.check_github_connection"],
+    ],
+    ids=["direct", "module"],
+)
+def test_github_diagnostic_imports_in_both_invocation_forms_without_network(
+    command: list[str],
+) -> None:
+    """Both entrypoints must reach configuration before requiring a token."""
+    result = run_diagnostic(command, without_token=True)
+    combined_output = result.stdout + result.stderr
+
+    assert result.returncode == 1
+    assert "[ERROR] GITHUB_TOKEN is missing." in result.stdout
+    assert "ModuleNotFoundError" not in combined_output