feat(N3): Backend respektiert X-Workspace-ID bei Listen — contacts/dms/mail/calendar (#367)

- Core-Resolver resolve_workspace_scope(): Zuweisungs-Check, leere Werte fallen weg; Exemptions System-Admin + workspaces:configure_modules (Editor-Deadlock)
- require_workspace_scope(module_key) FastAPI-Dependency (deps.py)
- expand_folder_scope(): Ordner-Subtree (zyklensicher) für ContactFolder + DMS Folder; scope_uuid_set() fail-closed
- contacts: folder_ids-Subtree + contact_types auf GET /contacts, List-Cache bei aktivem Scope deaktiviert (Cache-Leak-Gefahr)
- dms: folder_ids-Subtree + file_types (semantische Matcher) auf /files, Baum-Reduktion auf /folders
- mail: account_ids auf /mails, /threads, /accounts
- calendar: calendar_ids auf /calendar/entries, /calendars
- Frontend-Defaults: getModuleConfig() im workspaceStore, ContactsList default_saved_view_id, Calendar default_view
- Tests: 21/21 neu (TDD rot→grün), Regression 81 passed, Checker 0, tsc clean, Vitest grün, Build OK

app/services/workspace_scope_service.py

@@ -17,15 +17,179 @@ Without an active workspace there is no filter (backward compatible).
 from __future__ import annotations
 
 import logging
+import uuid
 from typing import Any
 
 from pydantic import ValidationError
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.models.workspace import Workspace, WorkspaceModule, WorkspaceUser
 from app.schemas.workspace import WorkspaceModuleScopes
 
 logger = logging.getLogger(__name__)
 
 
+async def resolve_workspace_scope(
+    db: AsyncSession,
+    current_user: dict[str, Any],
+    x_workspace_id: str | None,
+    module_key: str,
+) -> dict[str, Any] | None:
+    """Resolve the active workspace scope config for a module (Phase N3).
+
+    Returns the module's scope values (e.g. ``{"folder_ids": [...]}``) or
+    ``None`` when no restriction applies:
+    - no X-Workspace-ID header / invalid UUID → no filter (backward compatible)
+    - system admins → exempt
+    - holders of ``workspaces:configure_modules`` → exempt (editor deadlock:
+      the N2 scope editor loads its value options through the same endpoints)
+    - user not assigned to the workspace → no filter (fail-open to RLS/ABAC;
+      the /context endpoint reports ``not_assigned`` separately)
+    - module not configured or config has only empty values → no filter
+
+    Security invariant: the returned config is applied as a pure
+    AND-restriction by the callers — a workspace can never grant visibility.
+    """
+    if not x_workspace_id:
+        return None
+    try:
+        ws_id = uuid.UUID(x_workspace_id)
+    except (ValueError, AttributeError, TypeError):
+        return None
+
+    if current_user.get("is_system_admin"):
+        return None
+
+    from app.core.permissions import check_permission
+
+    if check_permission(current_user, "workspaces:configure_modules"):
+        return None
+
+    try:
+        tenant_id = uuid.UUID(current_user["tenant_id"])
+        user_id = uuid.UUID(current_user["user_id"])
+    except (KeyError, ValueError, TypeError):
+        return None
+
+    # Workspace exists, is active and belongs to the tenant
+    ws = (
+        await db.execute(
+            select(Workspace).where(
+                Workspace.id == ws_id,
+                Workspace.tenant_id == tenant_id,
+                Workspace.is_active == True,  # noqa: E712
+            )
+        )
+    ).scalar_one_or_none()
+    if ws is None:
+        return None
+
+    # User must be assigned to the workspace
+    wu = (
+        await db.execute(
+            select(WorkspaceUser).where(
+                WorkspaceUser.workspace_id == ws_id,
+                WorkspaceUser.user_id == user_id,
+                WorkspaceUser.tenant_id == tenant_id,
+            )
+        )
+    ).scalar_one_or_none()
+    if wu is None:
+        return None
+
+    # Module config for the requested module
+    wm = (
+        await db.execute(
+            select(WorkspaceModule).where(
+                WorkspaceModule.workspace_id == ws_id,
+                WorkspaceModule.tenant_id == tenant_id,
+                WorkspaceModule.module_key == module_key,
+            )
+        )
+    ).scalar_one_or_none()
+    if wm is None:
+        return None
+
+    config = wm.config or {}
+    # Empty values (empty list / None / "") mean no restriction per dimension
+    active = {k: v for k, v in config.items() if v}
+    return active or None
+
+
+async def expand_folder_scope(
+    db: AsyncSession,
+    model: type,
+    root_ids: list[str],
+) -> set[uuid.UUID] | None:
+    """Expand folder scope IDs to the full subtree (self + descendants).
+
+    Works for any folder model with ``id``/``parent_id`` (ContactFolder,
+    DMS Folder). Returns ``None`` when no valid IDs remain — callers treat
+    that as no restriction. Cycles are tolerated (visited set).
+    """
+    if not root_ids:
+        return None
+    try:
+        frontier = {uuid.UUID(v) for v in root_ids}
+    except (ValueError, TypeError, AttributeError):
+        return None
+    if not frontier:
+        return None
+
+    rows = (
+        await db.execute(select(model.id, model.parent_id))
+    ).all()
+    children_of: dict[uuid.UUID | None, set[uuid.UUID]] = {}
+    for fid, parent in rows:
+        children_of.setdefault(parent, set()).add(fid)
+
+    result = set(frontier)
+    queue = list(frontier)
+    while queue:
+        current = queue.pop()
+        for child in children_of.get(current, set()):
+            if child not in result:
+                result.add(child)
+                queue.append(child)
+    return result
+
+
+def scope_uuid_set(raw: Any) -> set[uuid.UUID] | None:
+    """Convert a scope dimension value into a set of UUIDs (Phase N3).
+
+    Returns ``None`` when the value is absent or not a list (no restriction).
+    Returns an EMPTY set when the list contains no valid UUIDs — callers use
+    it with ``.in_(empty)`` so a configured-but-garbage scope restricts to
+    nothing (fail-closed AND-restriction). Real editor configs always carry
+    valid UUIDs; this only guards against hand-corrupted JSONB.
+    """
+    if not isinstance(raw, list) or not raw:
+        return None
+    result: set[uuid.UUID] = set()
+    for value in raw:
+        try:
+            result.add(uuid.UUID(value))
+        except (ValueError, TypeError, AttributeError):
+            continue
+    return result
+
+
+DMS_FILE_TYPE_MATCHERS: dict[str, Any] = {
+    "application/pdf": lambda mime: mime == "application/pdf",
+    "image/": lambda mime: mime.startswith("image/"),
+    "spreadsheet": lambda mime: "spreadsheet" in mime or "excel" in mime,
+    "word": lambda mime: "word" in mime,
+    "other": lambda mime: (
+        mime != "application/pdf"
+        and not mime.startswith("image/")
+        and "spreadsheet" not in mime
+        and "excel" not in mime
+        and "word" not in mime
+    ),
+}
+
+
 def _parse_contribution(plugin_name: str, contribution: Any) -> WorkspaceModuleScopes | None:
     """Validate a single raw contribution; ``None`` when invalid (fail-closed).