Fix docs-only gate for binary files

src/hyrule_engineering_loop/gate_runner.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import json
 import subprocess
 import sys
 from pathlib import Path
@@ -90,14 +91,17 @@ def select_gate_commands_for_mutations(paths: Iterable[str]) -> list[list[str]]:
     if any(path.endswith(".py") for path in normalized):
         return [[sys.executable, "-m", "compileall", "-q", "."]]
     if all(path.startswith("docs/") or path.endswith((".md", ".txt", ".rst")) for path in normalized):
-        return [
-            [
-                sys.executable,
-                "-c",
-                (
-                    "from pathlib import Path; "
-                    "[p.read_text(encoding='utf-8') for p in Path('.').rglob('*') if p.is_file()]"
-                ),
-            ]
-        ]
+        paths_literal = repr(json.dumps(normalized))
+        script = (
+            "import json\n"
+            "from pathlib import Path\n"
+            f"for raw in json.loads({paths_literal}):\n"
+            "    path = Path(raw)\n"
+            "    if not path.exists():\n"
+            "        continue\n"
+            "    if not path.is_file():\n"
+            "        raise SystemExit(f'not a file: {raw}')\n"
+            "    path.read_text(encoding='utf-8')\n"
+        )
+        return [[sys.executable, "-c", script]]
     return [[sys.executable, "-c", "from pathlib import Path; assert any(Path('.').rglob('*'))"]]

tests/test_gate_runner.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from hyrule_engineering_loop.gate_runner import run_gate_commands, select_gate_commands_for_mutations
+
+
+def test_docs_gate_reads_only_mutated_text_paths(tmp_path) -> None:
+    (tmp_path / "docs").mkdir()
+    (tmp_path / "docs" / "note.md").write_text("hello\n", encoding="utf-8")
+    (tmp_path / "binary.bin").write_bytes(b"\xb8\x00not utf8")
+
+    commands = select_gate_commands_for_mutations(["engineering-loop:docs/note.md"])
+    results, errors = run_gate_commands(commands, cwd=tmp_path)
+
+    assert errors == []
+    assert results[0]["returncode"] == 0
+
+
+def test_docs_gate_reports_non_utf8_mutated_file(tmp_path) -> None:
+    (tmp_path / "docs").mkdir()
+    (tmp_path / "docs" / "note.md").write_bytes(b"\xb8\x00not utf8")
+
+    commands = select_gate_commands_for_mutations(["docs/note.md"])
+    results, errors = run_gate_commands(commands, cwd=tmp_path)
+
+    assert results[0]["returncode"] == 1
+    assert errors
+    assert "UnicodeDecodeError" in errors[0]["stderr"]