GraphRAG Studio — initial commit: multimodal RAG system with KG visualization

Full-stack application for document-to-knowledge-graph pipeline:
- Backend: FastAPI + LangGraph ReAct agent + DeepSeek + MinerU parsing
- Frontend: React 19 + Vite + D3.js + shadcn/ui
- Pipeline: MinerU parsing → LangExtract entity extraction → KG building

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/routers/kg.py

@@ -0,0 +1,72 @@
+"""C 组：知识图谱（6 个端点）"""
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+from models.schemas import APIResponse
+from services import kg_service as svc
+
+router = APIRouter(prefix="/kg", tags=["Knowledge Graph"])
+
+
+@router.get("/nodes")
+async def list_nodes(
+    type: str | None = None,
+    doc_id: str | None = None,
+    confidence: str | None = None,
+    page: int = 1,
+    page_size: int = 50,
+):
+    page_size = min(page_size, 200)
+    result = svc.get_nodes(page, page_size, type, doc_id, confidence)
+    if result["total"] == 0 and not any([type, doc_id, confidence]):
+        return JSONResponse(
+            status_code=400,
+            content=APIResponse.err(3002, "Knowledge graph is empty. Index documents first.").model_dump(),
+        )
+    return APIResponse.ok(result)
+
+
+@router.get("/edges")
+async def list_edges(
+    doc_id: str | None = None,
+    relation: str | None = None,
+    page: int = 1,
+    page_size: int = 100,
+):
+    page_size = min(page_size, 500)
+    result = svc.get_edges(page, page_size, doc_id, relation)
+    return APIResponse.ok(result)
+
+
+@router.get("/nodes/{node_id}")
+async def get_node_detail(node_id: str):
+    node = svc.get_node_detail(node_id)
+    if not node:
+        return JSONResponse(
+            status_code=404,
+            content=APIResponse.err(3001, f"Node '{node_id}' not found").model_dump(),
+        )
+    return APIResponse.ok(node)
+
+
+@router.get("/nodes/{node_id}/neighbors")
+async def get_node_neighbors(node_id: str, hops: int = 1):
+    result = svc.get_neighbors(node_id, hops)
+    if result is None:
+        return JSONResponse(
+            status_code=404,
+            content=APIResponse.err(3001, f"Node '{node_id}' not found").model_dump(),
+        )
+    return APIResponse.ok(result)
+
+
+@router.get("/stats")
+async def get_kg_stats():
+    stats = svc.get_stats()
+    return APIResponse.ok(stats)
+
+
+@router.get("/export")
+async def export_kg(format: str = "json", doc_id: str | None = None):
+    result = svc.export_kg(doc_id)
+    return APIResponse.ok(result)