1 files changed, 110 insertions, 0 deletions
diff --git a/hooks/tests/test_rulesets_write_boundary.py b/hooks/tests/test_rulesets_write_boundary.py
new file mode 100644
index 0000000..826a941
--- /dev/null
+++ b/hooks/tests/test_rulesets_write_boundary.py
@@ -0,0 +1,110 @@
+import json
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+
+SCRIPT = Path(__file__).parents[1] / "rulesets-write-boundary.py"
+
+
+def run_hook(payload: dict, rulesets: Path) -> dict | None:
+    proc = subprocess.run(
+        [sys.executable, str(SCRIPT)],
+        input=json.dumps(payload),
+        text=True,
+        capture_output=True,
+        env={**os.environ, "RULESETS_ROOT": str(rulesets)},
+        check=True,
+    )
+    return json.loads(proc.stdout) if proc.stdout else None
+
+
+def test_allows_write_from_rulesets_session(tmp_path):
+    rulesets = tmp_path / "rulesets"
+    rulesets.mkdir()
+    target = rulesets / "file"
+    result = run_hook(
+        {
+            "cwd": str(rulesets),
+            "tool_name": "Write",
+            "tool_input": {"file_path": str(target)},
+        },
+        rulesets,
+    )
+    assert result is None
+
+
+def test_blocks_absolute_cross_project_write(tmp_path):
+    rulesets = tmp_path / "rulesets"
+    other = tmp_path / "other"
+    rulesets.mkdir()
+    other.mkdir()
+    result = run_hook(
+        {
+            "cwd": str(other),
+            "tool_name": "Edit",
+            "tool_input": {"file_path": str(rulesets / "rule.md")},
+        },
+        rulesets,
+    )
+    assert result["hookSpecificOutput"]["permissionDecision"] == "deny"
+    assert "inbox-send rulesets" in result["hookSpecificOutput"][
+        "permissionDecisionReason"
+    ]
+
+
+def test_blocks_write_reached_through_symlink(tmp_path):
+    rulesets = tmp_path / "rulesets"
+    other = tmp_path / "other"
+    installed = tmp_path / "installed"
+    rulesets.mkdir()
+    other.mkdir()
+    (rulesets / "rules").mkdir()
+    installed.symlink_to(rulesets / "rules", target_is_directory=True)
+    result = run_hook(
+        {
+            "cwd": str(other),
+            "tool_name": "Write",
+            "tool_input": {"file_path": str(installed / "todo-format.md")},
+        },
+        rulesets,
+    )
+    assert result["hookSpecificOutput"]["permissionDecision"] == "deny"
+    assert str(rulesets) in result["systemMessage"]
+
+
+def test_blocks_apply_patch_target(tmp_path):
+    rulesets = tmp_path / "rulesets"
+    other = tmp_path / "other"
+    rulesets.mkdir()
+    other.mkdir()
+    patch = (
+        f"*** Begin Patch\n*** Update File: {rulesets / 'file'}\n"
+        "@@\n-old\n+new\n*** End Patch\n"
+    )
+    result = run_hook(
+        {
+            "cwd": str(other),
+            "tool_name": "apply_patch",
+            "tool_input": {"input": patch},
+        },
+        rulesets,
+    )
+    assert result["hookSpecificOutput"]["permissionDecision"] == "deny"
+
+
+def test_allows_unrelated_write(tmp_path):
+    rulesets = tmp_path / "rulesets"
+    other = tmp_path / "other"
+    rulesets.mkdir()
+    other.mkdir()
+    result = run_hook(
+        {
+            "cwd": str(other),
+            "tool_name": "Edit",
+            "tool_input": {"file_path": str(other / "file")},
+        },
+        rulesets,
+    )
+    assert result is None