feat!: require explicit user on every tenant-data endpoint

Remove the implicit jpmschweitzer default tenant (DEFAULT_USER) from
src/core/multi_tenancy.py and every endpoint and request model that
inherited it (~40 endpoints across /query, /wiki, /vector, /graph,
/ingest, /volatile, /documents, /stats, /rag).

- Add validate_required_user() + RequiredUser pydantic type in
  multi_tenancy and a shared require_user FastAPI dependency
  (RequiredUserQuery) that rejects missing, empty, and whitespace-only
  users with 422, following the /maintenance/* pattern.
- Wiki page create / smart-create / dossier request models now require
  user (no fallback in wiki_service).
- /maintenance/cleanup/test-data derives the tenant from the page path
  instead of using the production tenant collection.
- Wiki.js change listener skips changes when no tenant user can be
  derived from the notification email instead of defaulting to the
  production tenant.
- Consolidation service internal helpers no longer default to the
  production tenant.
- Tool catalog marks user as required with honest descriptions.
- OpenAPI descriptions updated honestly; CHANGELOG notes that callers
  (tatlock, Scheduler ingest tasks) must now send explicit user.
- Offline tests: 422 coverage for query/body endpoints, required-user
  validator tests; updated legacy tests that assumed a default tenant.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/core/dependencies.py

@@ -10,7 +10,7 @@ Provides FastAPI dependencies for service clients with:
 
 from functools import lru_cache
 from typing import Annotated
-from fastapi import Depends
+from fastapi import Depends, HTTPException, Query
 import logging
 
 import redis.asyncio as aioredis
@@ -38,6 +38,35 @@ logger = logging.getLogger(__name__)
 SettingsDep = Annotated[Settings, Depends(get_settings)]
 
 
+# Tenant user dependency
+def require_user(
+    user: str = Query(
+        ...,
+        description=(
+            "User identifier (tenant). Required — every operation is scoped to "
+            "this tenant's namespace (Qdrant collection, Neo4j labels, wiki path, "
+            "Redis keys). Requests without an explicit non-empty user are "
+            "rejected with 422. There is no default tenant."
+        ),
+    )
+) -> str:
+    """
+    FastAPI dependency: required tenant user query parameter.
+
+    Rejects missing (FastAPI returns 422 automatically), empty, and
+    whitespace-only user values. Use via the RequiredUserQuery alias.
+    """
+    from src.core.multi_tenancy import validate_required_user
+
+    try:
+        return validate_required_user(user)
+    except ValueError as e:
+        raise HTTPException(status_code=422, detail=str(e))
+
+
+RequiredUserQuery = Annotated[str, Depends(require_user)]
+
+
 # Client factory functions with @lru_cache for singletons
 @lru_cache
 def get_neo4j_client() -> Neo4jClient:

src/core/multi_tenancy.py

@@ -8,9 +8,9 @@ Provides utilities for user namespace management across:
 """
 
 import re
+from typing import Annotated
 
-# Default user for all operations
-DEFAULT_USER = "jpmschweitzer"
+from pydantic import AfterValidator
 
 
 def sanitize_user_id(user_id: str) -> str:
@@ -186,6 +186,45 @@ def validate_user_id(user_id: str) -> bool:
     return True
 
 
+def validate_required_user(user: str) -> str:
+    """
+    Validate that a tenant user identifier is present and usable.
+
+    There is NO default tenant: every operation that touches tenant data
+    must receive an explicit user. Empty or whitespace-only values are
+    rejected, as are values that fail :func:`validate_user_id`.
+
+    Args:
+        user: Raw user identifier from a request
+
+    Returns:
+        The stripped user identifier
+
+    Raises:
+        ValueError: If the user is missing, blank, or invalid
+
+    Examples:
+        >>> validate_required_user("llm_tester")
+        'llm_tester'
+        >>> validate_required_user("  ")
+        Traceback (most recent call last):
+        ...
+        ValueError: user is required and must be a non-empty, non-whitespace string
+    """
+    if user is None or not str(user).strip():
+        raise ValueError(
+            "user is required and must be a non-empty, non-whitespace string"
+        )
+    stripped = str(user).strip()
+    if not validate_user_id(stripped):
+        raise ValueError(f"Invalid user identifier: {user!r}")
+    return stripped
+
+
+# Pydantic annotated type for request models: a required, validated tenant user.
+RequiredUser = Annotated[str, AfterValidator(validate_required_user)]
+
+
 def is_path_in_user_namespace(path: str, user_id: str) -> bool:
     """
     Check if a Wiki.js path belongs to user's namespace.