feat(filesystem): enhance local mount path normalization and add error handling for missing parent directories

surfsense_backend/tests/unit/middleware/test_file_intent_middleware.py

@@ -79,7 +79,7 @@ async def test_file_write_null_filename_uses_semantic_default_path():
 
 
 @pytest.mark.asyncio
-async def test_file_write_null_filename_infers_json_extension():
+async def test_file_write_null_filename_defaults_to_markdown_path():
     llm = _FakeLLM(
         '{"intent":"file_write","confidence":0.71,"suggested_filename":null}'
     )
@@ -94,7 +94,7 @@ async def test_file_write_null_filename_infers_json_extension():
     assert result is not None
     contract = result["file_operation_contract"]
     assert contract["intent"] == FileOperationIntent.FILE_WRITE.value
-    assert contract["suggested_path"] == "/notes.json"
+    assert contract["suggested_path"] == "/notes.md"
 
 
 @pytest.mark.asyncio

surfsense_backend/tests/unit/middleware/test_filesystem_verification.py

@@ -34,6 +34,11 @@ class _RuntimeNoSuggestedPath:
     state = {"file_operation_contract": {}}
 
 
+class _RuntimeWithSuggestedPath:
+    def __init__(self, suggested_path: str) -> None:
+        self.state = {"file_operation_contract": {"suggested_path": suggested_path}}
+
+
 def test_verify_written_content_prefers_raw_sync() -> None:
     middleware = SurfSenseFilesystemMiddleware.__new__(SurfSenseFilesystemMiddleware)
     expected = "line1\nline2"
@@ -162,3 +167,47 @@ def test_normalize_local_mount_path_prefixes_posix_absolute_path_for_linux_and_m
     resolved = middleware._normalize_local_mount_path("/var/log/app.log", runtime)  # type: ignore[arg-type]
 
     assert resolved == "/pc_backups/var/log/app.log"
+
+
+def test_normalize_local_mount_path_prefers_unique_existing_parent_mount(
+    tmp_path: Path,
+) -> None:
+    root_a = tmp_path / "RootA"
+    root_b = tmp_path / "RootB"
+    (root_a / "other").mkdir(parents=True)
+    (root_b / "nested" / "deep").mkdir(parents=True)
+    backend = MultiRootLocalFolderBackend(
+        (("root_a", str(root_a)), ("root_b", str(root_b)))
+    )
+    runtime = _RuntimeNoSuggestedPath()
+    middleware = SurfSenseFilesystemMiddleware.__new__(SurfSenseFilesystemMiddleware)
+    middleware._get_backend = lambda _runtime: backend  # type: ignore[method-assign]
+
+    resolved = middleware._normalize_local_mount_path(  # type: ignore[arg-type]
+        "/nested/deep/new-note.md",
+        runtime,
+    )
+
+    assert resolved == "/root_b/nested/deep/new-note.md"
+
+
+def test_normalize_local_mount_path_uses_suggested_mount_when_ambiguous(
+    tmp_path: Path,
+) -> None:
+    root_a = tmp_path / "RootA"
+    root_b = tmp_path / "RootB"
+    root_a.mkdir(parents=True)
+    root_b.mkdir(parents=True)
+    backend = MultiRootLocalFolderBackend(
+        (("root_a", str(root_a)), ("root_b", str(root_b)))
+    )
+    runtime = _RuntimeWithSuggestedPath("/root_b/notes/context.md")
+    middleware = SurfSenseFilesystemMiddleware.__new__(SurfSenseFilesystemMiddleware)
+    middleware._get_backend = lambda _runtime: backend  # type: ignore[method-assign]
+
+    resolved = middleware._normalize_local_mount_path(  # type: ignore[arg-type]
+        "/brand-new-note.md",
+        runtime,
+    )
+
+    assert resolved == "/root_b/brand-new-note.md"

surfsense_backend/tests/unit/middleware/test_local_folder_backend.py

@@ -9,6 +9,7 @@ pytestmark = pytest.mark.unit
 
 def test_local_backend_write_read_edit_roundtrip(tmp_path: Path):
     backend = LocalFolderBackend(str(tmp_path))
+    (tmp_path / "notes").mkdir()
 
     write = backend.write("/notes/test.md", "line1\nline2")
     assert write.error is None
@@ -51,9 +52,20 @@ def test_local_backend_glob_and_grep(tmp_path: Path):
 
 def test_local_backend_read_raw_returns_exact_content(tmp_path: Path):
     backend = LocalFolderBackend(str(tmp_path))
+    (tmp_path / "notes").mkdir()
     expected = "# Title\n\nline 1\nline 2\n"
     write = backend.write("/notes/raw.md", expected)
     assert write.error is None
 
     raw = backend.read_raw("/notes/raw.md")
     assert raw == expected
+
+
+def test_local_backend_write_rejects_missing_parent_directory(tmp_path: Path):
+    backend = LocalFolderBackend(str(tmp_path))
+
+    write = backend.write("/tempoo/new-note.md", "# New note")
+
+    assert write.error is not None
+    assert "parent directory" in write.error
+    assert not (tmp_path / "tempoo").exists()