diff --git a/pyproject.toml b/pyproject.toml
index 337f7d20..320e9312 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -58,6 +58,7 @@ agentdescent = ["integrations/*.md", "integrations/*.json"]
 [tool.pytest.ini_options]
 testpaths = ["tests"]
 addopts = "-q"
-# Put the repo root on sys.path so `import agentdescent` / `import examples`
-# resolve under a bare `pytest` invocation (CI), not just `python -m pytest`.
-pythonpath = ["."]
+# Put both the repo root and tests directory on sys.path. The root resolves
+# package imports; tests keeps legacy top-level test helpers importable after
+# making `tests` an explicit package for subprocess-based refs.
+pythonpath = [".", "tests"]
diff --git a/scripts/__init__.py b/scripts/__init__.py
new file mode 100644
index 00000000..d2b633e4
--- /dev/null
+++ b/scripts/__init__.py
@@ -0,0 +1 @@
+"""Repository scripts imported by tests and development tools."""
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 00000000..229772d2
--- /dev/null
+++ b/tests/__init__.py
@@ -0,0 +1 @@
+"""Local test helpers imported by subprocess-based integration tests."""
diff --git a/tests/test_test_package_resolution.py b/tests/test_test_package_resolution.py
new file mode 100644
index 00000000..c4e9caef
--- /dev/null
+++ b/tests/test_test_package_resolution.py
@@ -0,0 +1,38 @@
+"""Local test helpers must win over unrelated installed packages."""
+
+import os
+from pathlib import Path
+import subprocess
+import sys
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def test_repository_test_and_script_packages_win_over_installed_packages(tmp_path):
+    fake_site = tmp_path / "site-packages"
+    for name in ("tests", "scripts"):
+        conflicting = fake_site / name
+        conflicting.mkdir(parents=True)
+        (conflicting / "__init__.py").write_text(
+            f"# simulated installed {name} package\n"
+        )
+
+    env = os.environ.copy()
+    env["PYTHONPATH"] = os.pathsep.join((str(fake_site), str(ROOT / "tests")))
+    code = (
+        "import tests.test_evolvespec, scripts.audit_workloads, faults, audit_ppi_cases; "
+        "import tests, scripts; print(tests.__file__); print(scripts.__file__)"
+    )
+    result = subprocess.run(
+        [sys.executable, "-c", code],
+        cwd=ROOT,
+        env=env,
+        text=True,
+        capture_output=True,
+        check=False,
+    )
+
+    assert result.returncode == 0, result.stdout + result.stderr
+    assert str(ROOT / "tests" / "__init__.py") in result.stdout
+    assert str(ROOT / "scripts" / "__init__.py") in result.stdout