fix: reject absolute urls in the content resolver, register the mutants

Review CODE-REVIEW-225-r1.

M1: urlsplit(url).path was trusted even when the url carried a scheme or an
authority, so "https://evil.example/houseplan_files/files/m1/doc.pdf"
resolved onto a local file while _looks_internal kept calling it external —
the mirror image of the inconsistency this resolver exists to prevent. Only a
same-document reference is resolved by its path now.

M2: the three mutants the spec described are registered in
scripts/mutation-gate.mjs instead of living as a one-off manual run. The
traversal entry drops both structural checks at once on purpose: taken one at
a time the defence is layered (sanitize_marker_id turns ".." into "misc") and
the mutant would be equivalent — established by running it.

Issue: #225
User-Visible: no

custom_components/houseplan/import_export.py

@@ -357,7 +357,16 @@ def _internal_path(root: Path, url: str) -> tuple[str, Path] | None:
     # every backup holding one refused to import (issue #225). Path segments
     # keep doing the guarding: dropping the query cannot widen what a segment
     # is allowed to be.
-    url = urlsplit(url).path
+    #
+    # Only a same-document reference may be trusted this way: with a scheme or
+    # an authority the path belongs to another host, and taking it would let
+    # "https://evil.example/houseplan_files/files/m1/doc.pdf" resolve onto a
+    # local file (review CODE-REVIEW-225-r1, M1). Such a url stays external,
+    # which is also what _looks_internal says about it.
+    parsed = urlsplit(url)
+    if parsed.scheme or parsed.netloc:
+        return None
+    url = parsed.path
     content_plan = CONTENT_URL + "/plans/_/"
     if url.startswith(content_plan) or url.startswith(PLANS_URL + "/"):
         prefix = content_plan if url.startswith(content_plan) else PLANS_URL + "/"

scripts/mutation-gate.mjs

@@ -703,6 +703,47 @@ export const MUTANTS = [
       replace: '    .dev:not(.unavail):hover {',
     }],
   },
+  {
+    id: 'internal-path-ignores-query',
+    guard: 'node scripts/backend-test-guard.mjs issue_225',
+    because: 'разбор url строкой вместо urlsplit возвращает баг #225: кэш-бастер '
+      + '?v=… делает имя файла не равным самому себе, ссылка читается как '
+      + 'внутренняя-но-неканоническая, и бэкап с вложением снова не импортируется',
+    patches: [{
+      file: 'custom_components/houseplan/import_export.py',
+      find: '    parsed = urlsplit(url)\n    if parsed.scheme or parsed.netloc:\n        return None\n    url = parsed.path',
+      replace: '    url = url.split("?", 1)[0]',
+    }],
+  },
+  {
+    id: 'internal-path-trusts-foreign-host',
+    guard: 'node scripts/backend-test-guard.mjs issue_225',
+    because: 'доверие к path при наличии scheme/netloc позволяет '
+      + '"https://evil.example/houseplan_files/files/m1/doc.pdf" разрешиться в локальный '
+      + 'файл, хотя _looks_internal считает такую ссылку внешней (ревью r1, M1)',
+    patches: [{
+      file: 'custom_components/houseplan/import_export.py',
+      find: '    if parsed.scheme or parsed.netloc:\n        return None',
+      replace: '    if False:\n        return None',
+    }],
+  },
+  {
+    id: 'internal-path-allows-traversal',
+    guard: 'node scripts/backend-test-guard.mjs issue_225',
+    because: 'структурные проверки пути — единственное, что режет traversal после '
+      + 'отделения query; снимать их нельзя. Мутант снимает обе сразу: по одной '
+      + 'защита эшелонирована (sanitize-сравнение ловит "..") и мутант был бы '
+      + 'эквивалентным — выяснено прогоном при реализации',
+    patches: [{
+      file: 'custom_components/houseplan/import_export.py',
+      find: '        if not raw_name or "/" in raw_name:\n            return None',
+      replace: '        raw_name = raw_name.split("/")[-1]\n        if not raw_name:\n            return None',
+    }, {
+      file: 'custom_components/houseplan/import_export.py',
+      find: '            tail = url[len(prefix):].split("/")\n            if len(tail) != 2:\n                return None',
+      replace: '            tail = url[len(prefix):].split("/")[-2:]',
+    }],
+  },
 ];
 
 // --- механика ---------------------------------------------------------------

tests_backend/test_ha_import_export.py

@@ -164,6 +164,26 @@ def test_issue_225_external_url_is_still_external(tmp_path: Path) -> None:
     assert import_export_api._looks_internal("https://example.invalid/floor.svg?v=1") is False
 
 
+@pytest.mark.parametrize("url", [
+    f"https://evil.example{FILES_URL}/m1/doc.pdf",
+    f"https://evil.example{CONTENT_URL}/files/m1/doc.pdf?v=1",
+    f"//evil.example{FILES_URL}/m1/doc.pdf",
+    f"https://evil.example{PLANS_URL}/f1.svg",
+])
+def test_issue_225_absolute_url_never_resolves_onto_a_local_file(
+    tmp_path: Path, url: str,
+) -> None:
+    """AC5: only a same-document reference may be resolved by its path.
+
+    A scheme or an authority means the path belongs to another host. Taking it
+    would let a crafted document describe an outside link as a local file —
+    the same inconsistency the resolver is meant to prevent, mirrored
+    (review CODE-REVIEW-225-r1, M1).
+    """
+    assert import_export_api._internal_path(tmp_path, url) is None
+    assert import_export_api._looks_internal(url) is False
+
+
 @pytest.mark.parametrize("same_source, expected_state, expected_confirmation", [
     (True, "available", False),
     (False, "detach_required", True),