feat: add GET /stats endpoint with system statistics

Returns counts for:
- Neo4j: nodes by type (Document, Entity, Collection, Search)
- Qdrant: vectors per collection
- Wiki.js: total page count
- Paperless: documents, tags, correspondents, document types

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

TODO.md

@@ -41,12 +41,3 @@ Check for duplicate or highly similar documents using vector similarity and grap
 3. Check graph relationships
 4. Return candidates with similarity scores
 
-## System Statistics
-
-#### `GET /stats`
-Get system statistics (wiki pages, neo4j nodes, qdrant vectors).
-
-**Implementation needed:**
-- Query Neo4j for node count
-- Query Qdrant for vector count
-- Query Wiki.js for page count

src/main.py

@@ -18,7 +18,7 @@ from pathlib import Path
 
 from src.config import Settings, get_settings, __version__
 from src.core.dependencies import (
-    verify_api_key, QdrantDep, WikiJSDep, OllamaDep, Neo4jDep
+    verify_api_key, QdrantDep, WikiJSDep, OllamaDep, Neo4jDep, PaperlessDep
 )
 from src.core.multi_tenancy import DEFAULT_USER
 
@@ -85,6 +85,14 @@ class HealthResponse(BaseModel):
     services: Dict[str, Any]
 
 
+class StatsResponse(BaseModel):
+    """System statistics response model."""
+    neo4j: Dict[str, int]
+    qdrant: Dict[str, Any]
+    wiki_pages: int
+    paperless: Dict[str, Any]
+
+
 # Routes
 @app.get("/", tags=["Root"])
 async def root() -> Dict[str, str]:
@@ -141,6 +149,85 @@ async def health(settings: Settings = Depends(get_settings)) -> HealthResponse:
     )
 
 
+@app.get("/stats", response_model=StatsResponse, tags=["System"])
+async def stats(
+    user: str = Query(default=DEFAULT_USER, description="User identifier"),
+    neo4j: Neo4jDep = None,
+    qdrant: QdrantDep = None,
+    wikijs: WikiJSDep = None,
+    paperless: PaperlessDep = None,
+    api_key: str = Depends(verify_api_key)
+) -> StatsResponse:
+    """
+    Get system statistics.
+
+    Returns counts for:
+    - Neo4j: nodes by type (Document, Entity, Collection, Search)
+    - Qdrant: vectors per collection
+    - Wiki.js: total page count
+    - Paperless: documents, tags, correspondents, document types
+    """
+    # Neo4j node counts by label
+    neo4j_stats = {}
+    try:
+        for label in ["Document", "Entity", "Collection", "Search"]:
+            result = await neo4j.execute_query(
+                f"MATCH (n:{label}) RETURN count(n) as count"
+            )
+            neo4j_stats[label.lower() + "_nodes"] = result[0]["count"] if result else 0
+    except Exception as e:
+        logger.error(f"Failed to get Neo4j stats: {e}")
+        neo4j_stats = {"error": str(e)}
+
+    # Qdrant collection stats
+    qdrant_stats = {}
+    try:
+        collections = await qdrant.list_collections()
+        qdrant_stats["collections"] = len(collections)
+        qdrant_stats["total_vectors"] = sum(c.get("vectors_count", 0) for c in collections)
+        qdrant_stats["by_collection"] = {
+            c["name"]: c["vectors_count"] for c in collections
+        }
+    except Exception as e:
+        logger.error(f"Failed to get Qdrant stats: {e}")
+        qdrant_stats = {"error": str(e)}
+
+    # Wiki.js page count
+    wiki_pages = 0
+    try:
+        pages = await wikijs.list_all_pages(user)
+        wiki_pages = len(pages)
+    except Exception as e:
+        logger.warning(f"Failed to get Wiki.js stats: {e}")
+
+    # Paperless-ngx document stats
+    paperless_stats = {}
+    try:
+        # Get document count (page_size=1 for efficiency, we just need the count)
+        docs_result = await paperless.list_documents(page_size=1)
+        paperless_stats["documents"] = docs_result.get("count", 0)
+
+        # Get metadata counts
+        tags = await paperless.list_tags()
+        paperless_stats["tags"] = len(tags)
+
+        correspondents = await paperless.list_correspondents()
+        paperless_stats["correspondents"] = len(correspondents)
+
+        doc_types = await paperless.list_document_types()
+        paperless_stats["document_types"] = len(doc_types)
+    except Exception as e:
+        logger.warning(f"Failed to get Paperless stats: {e}")
+        paperless_stats = {"error": str(e)}
+
+    return StatsResponse(
+        neo4j=neo4j_stats,
+        qdrant=qdrant_stats,
+        wiki_pages=wiki_pages,
+        paperless=paperless_stats
+    )
+
+
 @app.post("/ingest/check-updates", tags=["Ingestion"])
 async def check_updates(
     documents: Dict[str, Any],