fix(webdav): address PR #764 review round 2

Addresses the four points raised in the automated review on PR #764:

1. Scope guards on the four search tools (search_files, find_by_name,
   find_by_type, list_favorites) so an excluded `scope` raises ToolError
   instead of silently returning an empty result. Previously an LLM
   could probe the asymmetry between list_directory (raises) and the
   search tools (silent) to infer that an excluded directory exists.
   The 4 search tools now mirror the early-guard pattern from
   list_directory and avoid an unnecessary upstream query for known-
   excluded scopes.

2. Concurrent per-tag resolution in get_excluded_file_paths via
   anyio.create_task_group(). Previously the 2N network calls (1
   PROPFIND + 1 REPORT per tag) ran serially. Per-tag fail-open
   behaviour is preserved by extracting _resolve_one_tag, which
   swallows its own exceptions so a single tag failure does not abort
   the surrounding task group.

3. WebDAVClient.get_tag_by_name and get_files_by_tag now route through
   _make_request, inheriting the @retry_on_429 decorator. Previously
   they bypassed it; with tag exclusion invoked on every WebDAV tool
   call, a transient 429 from the systemtags endpoint was hitting the
   fail-open path instead of being transparently retried.

4. Test coverage: 6 new tests in test_webdav_tools_exclusion.py (4
   scope-guard, 2 missing filter tests for find_by_type and
   list_favorites) and 2 new tests in test_tag_exclusion.py (a
   concurrency proof using an event-barrier that would deadlock under
   sequential execution, and a fail-open-under-task-group test with
   order-independent side_effect callables).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/client/webdav.py

@@ -1132,13 +1132,12 @@ class WebDAVClient(BaseNextcloudClient):
   </d:prop>
 </d:propfind>"""
 
-        response = await self._client.request(
+        response = await self._make_request(
             "PROPFIND",
             "/remote.php/dav/systemtags/",
             headers={"Depth": "1"},
             content=propfind_body,
         )
-        response.raise_for_status()
 
         # Parse XML response
         root = ET.fromstring(response.content)
@@ -1216,12 +1215,11 @@ class WebDAVClient(BaseNextcloudClient):
   </oc:filter-rules>
 </oc:filter-files>"""
 
-        response = await self._client.request(
+        response = await self._make_request(
             "REPORT",
             f"{self._get_webdav_base_path()}/",
             content=report_body,
         )
-        response.raise_for_status()
 
         # Parse XML response
         root = ET.fromstring(response.content)

nextcloud_mcp_server/server/tag_exclusion.py

@@ -23,6 +23,8 @@ is created with ``user_assignable=false``.
 
 import logging
 
+import anyio
+
 from nextcloud_mcp_server.client.webdav import WebDAVClient
 from nextcloud_mcp_server.config import get_settings
 
@@ -37,12 +39,65 @@ def get_excluded_tag_names() -> list[str]:
     return [t.strip() for t in raw.split(",") if t.strip()]
 
 
+async def _resolve_one_tag(
+    tag_name: str,
+    webdav: WebDAVClient,
+    excluded: set[str],
+    lock: anyio.Lock,
+) -> None:
+    """Resolve a single tag's paths and merge into *excluded* under *lock*.
+
+    Swallows its own exceptions so a failure for one tag does not abort
+    the surrounding task group (preserves fail-open per-tag semantics).
+    """
+    try:
+        tag = await webdav.get_tag_by_name(tag_name)
+    except Exception as e:
+        logger.warning(
+            "Tag exclusion lookup failed for tag %r (%s); "
+            "skipping — files tagged with this tag will be visible",
+            tag_name,
+            e,
+        )
+        return
+
+    if tag is None:
+        logger.debug("Excluded tag %r does not exist — skipping", tag_name)
+        return
+
+    try:
+        files = await webdav.get_files_by_tag(tag["id"])
+    except Exception as e:
+        logger.warning(
+            "Tag exclusion file enumeration failed for tag %r (%s); "
+            "skipping — files tagged with this tag will be visible",
+            tag_name,
+            e,
+        )
+        return
+
+    async with lock:
+        for f in files:
+            path = _normalise_path(f["path"])
+            excluded.add(path)
+            if f.get("is_directory"):
+                logger.debug(
+                    "Excluding directory %r (tag %r) — descendants will be hidden",
+                    path,
+                    tag_name,
+                )
+
+
 async def get_excluded_file_paths(webdav: WebDAVClient) -> set[str]:
     """Resolve excluded tags to the set of paths they cover.
 
     Tagged directories are added as their own normalised path; descendants
     are blocked via prefix match in :func:`is_path_excluded`.
 
+    Per-tag resolution is fanned out via ``anyio.create_task_group`` so
+    that the 2N network calls (1 PROPFIND + 1 REPORT per tag) run
+    concurrently rather than serially.
+
     **Failure mode is fail-open per tag**: if the systemtags endpoint is
     unreachable or returns an error for a given tag, that tag is skipped
     with a warning rather than propagating the error. Reasoning: the
@@ -56,42 +111,10 @@ async def get_excluded_file_paths(webdav: WebDAVClient) -> set[str]:
         return set()
 
     excluded: set[str] = set()
-    for tag_name in tag_names:
-        try:
-            tag = await webdav.get_tag_by_name(tag_name)
-        except Exception as e:
-            logger.warning(
-                "Tag exclusion lookup failed for tag %r (%s); "
-                "skipping — files tagged with this tag will be visible",
-                tag_name,
-                e,
-            )
-            continue
-
-        if tag is None:
-            logger.debug("Excluded tag %r does not exist — skipping", tag_name)
-            continue
-
-        try:
-            files = await webdav.get_files_by_tag(tag["id"])
-        except Exception as e:
-            logger.warning(
-                "Tag exclusion file enumeration failed for tag %r (%s); "
-                "skipping — files tagged with this tag will be visible",
-                tag_name,
-                e,
-            )
-            continue
-
-        for f in files:
-            path = _normalise_path(f["path"])
-            excluded.add(path)
-            if f.get("is_directory"):
-                logger.debug(
-                    "Excluding directory %r (tag %r) — descendants will be hidden",
-                    path,
-                    tag_name,
-                )
+    lock = anyio.Lock()
+    async with anyio.create_task_group() as tg:
+        for tag_name in tag_names:
+            tg.start_soon(_resolve_one_tag, tag_name, webdav, excluded, lock)
 
     if excluded:
         # `len(excluded)` counts directly-tagged entries — descendants of

nextcloud_mcp_server/server/webdav.py

@@ -392,6 +392,13 @@ def configure_webdav_tools(mcp: FastMCP):
         """
         client = await get_client(ctx)
 
+        # Resolve once and use for both the scope guard and the result filter.
+        excluded = await get_excluded_file_paths(client.webdav)
+        if scope and is_path_excluded(scope, excluded):
+            raise ToolError(
+                f"Access denied: scope {scope!r} is tagged with an excluded tag"
+            )
+
         # Build where conditions based on filters
         conditions = []
 
@@ -462,8 +469,7 @@ def configure_webdav_tools(mcp: FastMCP):
             limit=limit,
         )
 
-        # Filter out tagged-excluded paths.
-        excluded = await get_excluded_file_paths(client.webdav)
+        # Filter out tagged-excluded paths from the result set.
         if excluded:
             results = [
                 r for r in results if not is_path_excluded(r.get("path", ""), excluded)
@@ -511,10 +517,14 @@ def configure_webdav_tools(mcp: FastMCP):
             SearchFilesResponse with list of matching files
         """
         client = await get_client(ctx)
+        excluded = await get_excluded_file_paths(client.webdav)
+        if scope and is_path_excluded(scope, excluded):
+            raise ToolError(
+                f"Access denied: scope {scope!r} is tagged with an excluded tag"
+            )
         results = await client.webdav.find_by_name(
             pattern=pattern, scope=scope, limit=limit
         )
-        excluded = await get_excluded_file_paths(client.webdav)
         if excluded:
             results = [
                 r for r in results if not is_path_excluded(r.get("path", ""), excluded)
@@ -550,10 +560,14 @@ def configure_webdav_tools(mcp: FastMCP):
             SearchFilesResponse with list of matching files
         """
         client = await get_client(ctx)
+        excluded = await get_excluded_file_paths(client.webdav)
+        if scope and is_path_excluded(scope, excluded):
+            raise ToolError(
+                f"Access denied: scope {scope!r} is tagged with an excluded tag"
+            )
         results = await client.webdav.find_by_type(
             mime_type=mime_type, scope=scope, limit=limit
         )
-        excluded = await get_excluded_file_paths(client.webdav)
         if excluded:
             results = [
                 r for r in results if not is_path_excluded(r.get("path", ""), excluded)
@@ -588,8 +602,12 @@ def configure_webdav_tools(mcp: FastMCP):
             SearchFilesResponse with list of favorite files
         """
         client = await get_client(ctx)
-        results = await client.webdav.list_favorites(scope=scope, limit=limit)
         excluded = await get_excluded_file_paths(client.webdav)
+        if scope and is_path_excluded(scope, excluded):
+            raise ToolError(
+                f"Access denied: scope {scope!r} is tagged with an excluded tag"
+            )
+        results = await client.webdav.list_favorites(scope=scope, limit=limit)
         if excluded:
             results = [
                 r for r in results if not is_path_excluded(r.get("path", ""), excluded)