ci: block repository media assets (#256)

* ci: block repository media assets

* test: stabilize cascade scanner loop test

tests/unit/test_scripts/test_check_repo_assets.py

@@ -0,0 +1,80 @@
+"""Self-tests for ``scripts/check_repo_assets.py``."""
+
+from __future__ import annotations
+
+import importlib.util
+import sys
+from pathlib import Path
+
+_REPO_ROOT = Path(__file__).resolve().parents[3]
+_CHECKER_PATH = _REPO_ROOT / "scripts" / "check_repo_assets.py"
+
+
+def _load_checker():
+    assert _CHECKER_PATH.exists(), "repo asset checker should exist"
+    spec = importlib.util.spec_from_file_location("_repo_asset_checker", _CHECKER_PATH)
+    assert spec and spec.loader
+    mod = importlib.util.module_from_spec(spec)
+    sys.modules[spec.name] = mod
+    spec.loader.exec_module(mod)
+    return mod
+
+
+def test_clean_source_and_docs_paths_are_allowed() -> None:
+    checker = _load_checker()
+
+    violations = checker.find_violations(
+        [
+            "README.md",
+            "docs/engineering.md",
+            "src/everos/__init__.py",
+            "use-cases/claude-code-plugin/dashboard/dashboard.html",
+        ]
+    )
+
+    assert violations == []
+
+
+def test_image_extensions_are_blocked() -> None:
+    checker = _load_checker()
+
+    violations = checker.find_violations(["docs/banner.png", "icons/logo.svg"])
+
+    assert [violation.path for violation in violations] == [
+        "docs/banner.png",
+        "icons/logo.svg",
+    ]
+    assert {violation.reason for violation in violations} == {"image file"}
+
+
+def test_video_extensions_are_blocked() -> None:
+    checker = _load_checker()
+
+    violations = checker.find_violations(["demo/launch.mp4", "docs/clip.webm"])
+
+    assert [violation.path for violation in violations] == [
+        "demo/launch.mp4",
+        "docs/clip.webm",
+    ]
+    assert {violation.reason for violation in violations} == {"video file"}
+
+
+def test_asset_and_media_directories_are_blocked() -> None:
+    checker = _load_checker()
+
+    violations = checker.find_violations(
+        [
+            "assets/banner.txt",
+            "docs/images/diagram.txt",
+            "use-cases/example/media/story.md",
+            "use-cases/example/videos/walkthrough.md",
+        ]
+    )
+
+    assert [violation.path for violation in violations] == [
+        "assets/banner.txt",
+        "docs/images/diagram.txt",
+        "use-cases/example/media/story.md",
+        "use-cases/example/videos/walkthrough.md",
+    ]
+    assert {violation.reason for violation in violations} == {"asset/media directory"}