diff --git a/app/routers/query.py b/app/routers/query.py
new file mode 100644
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--- /dev/null
+++ b/app/routers/query.py
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+"""
+app/routers/query.py — Query-Endpunkte (WP-04)
+
+Zweck:
+    Stellt POST /query bereit und ruft den passenden Retriever-Modus auf.
+Kompatibilität:
+    Python 3.12+, FastAPI 0.110+
+Version:
+    0.1.0  (Erstanlage)
+Stand:
+    2025-10-07
+Bezug:
+    - app/core/retriever.py
+    - app/models/dto.py
+Nutzung:
+    app.include_router(query.router, prefix="/query", tags=["query"])
+Änderungsverlauf:
+    0.1.0 (2025-10-07) – Erstanlage.
+"""
+
+from __future__ import annotations
+from fastapi import APIRouter, HTTPException
+from app.models.dto import QueryRequest, QueryResponse
+from app.core.retriever import hybrid_retrieve, semantic_retrieve
+
+router = APIRouter()
+
+@router.post("", response_model=QueryResponse)
+def post_query(req: QueryRequest) -> QueryResponse:
+    try:
+        if req.mode == "semantic":
+            return semantic_retrieve(req)
+        # default: hybrid
+        return hybrid_retrieve(req)
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    except Exception as e:
+        raise HTTPException(status_code=500, detail=f"query failed: {e}")