feat(integrations): add LangChain integration — retriever, vectorstor… (#1155)

* feat(integrations): add LangChain integration — retriever, vectorstore, tools

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(langchain): address Qodo review on HybridSearch hits and tools

Read nested HybridSearch metadata so retriever/vectorstore Documents
are not empty, make the agent tools real BaseTool subclasses, and
stop slicing tool JSON into invalid payloads.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
Derek Tapley
2026-08-26 18:29:22 +05:00
committed by GitHub
co-authored by Cursor
parent 8a990c8bf5
commit f0aa581318
14 changed files with 1469 additions and 14 deletions
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"""
Semantica Framework Integrations
Optional integration packages for agentic frameworks (Google ADK, Claude Agent SDK, Agno, etc.).
Optional integration packages for agentic frameworks (Google ADK, Claude Agent SDK, Agno, CrewAI, LangChain, etc.).
Each integration is self-contained, independently installable via extras_require, and maintains
zero impact on core Semantica - keeping the semantic layer lean while maximizing ecosystem reach.
"""
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# Semantica × LangChain
Drop Semantica into existing LangChain / LangGraph pipelines: GraphRAG-style
retrieval, a `VectorStore` adapter, and agent tools.
## Install
```bash
pip install semantica[langchain]
# or just the core adapter dependency:
pip install langchain-core
```
## Retriever (GraphRAG)
```python
from integrations.langchain import SemanticaRetriever
from semantica.context import ContextGraph
from semantica.vector_store import HybridSearch
graph = ContextGraph()
hybrid = HybridSearch()
retriever = SemanticaRetriever(graph=graph, hybrid=hybrid, hops=2, top_k=10)
# Use with any LangChain chain that accepts a retriever:
from langchain.chains import RetrievalQA
qa = RetrievalQA.from_chain_type(llm=llm, retriever=retriever)
```
Hybrid search seeds retrieval; then graph edges are walked `hops` steps so
results go beyond flat vector similarity.
## VectorStore
```python
from integrations.langchain import SemanticaVectorStore
store = SemanticaVectorStore(hybrid=hybrid)
store.add_texts(["document one", "document two"], metadatas=[{"source": "a"}, {"source": "b"}])
docs = store.similarity_search("document", k=2)
docs, scores = store.similarity_search_with_score("document", k=2)
```
## Agent tools (LangGraph / tool-calling agents)
```python
from integrations.langchain import SemanticaKGTool, SemanticaDecisionTool
from langgraph.prebuilt import create_react_agent
tools = [
SemanticaKGTool(graph),
SemanticaDecisionTool(graph),
]
agent = create_react_agent(model, tools)
```
- `semantica_query_graph` — query the shared context graph (keyword / NL)
- `semantica_query_decisions` — search the recorded decision log
## Compatibility
- Requires `langchain-core >= 0.3`.
- All classes degrade gracefully when `langchain-core` is absent: they remain
importable (carrying the full Semantica API), and `build()` returns `None`,
so agents can branch on `LANGCHAIN_AVAILABLE`.
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"""
Semantica × LangChain Integration
=================================
First-class integration between the Semantica semantic intelligence stack and
the `LangChain <https://github.com/langchain-ai/langchain>`_ / LangGraph
ecosystem.
Public surface
--------------
SemanticaRetriever — ``BaseRetriever`` with multi-hop GraphRAG (walks graph
edges from hybrid-search hits)
SemanticaVectorStore — ``VectorStore`` adapter over Semantica's hybrid search
(drop-in for RetrievalQA / LCEL chains)
SemanticaKGTool — ``BaseTool`` for querying the context graph
SemanticaDecisionTool — ``BaseTool`` exposing the recorded decision log
Quick start
-----------
pip install semantica[langchain]
>>> from integrations.langchain import (
... SemanticaRetriever,
... SemanticaVectorStore,
... SemanticaKGTool,
... SemanticaDecisionTool,
... )
Compatibility
-------------
Requires ``langchain-core >= 0.3``. All classes degrade gracefully when
``langchain-core`` is not installed — they are still importable and carry the
full Semantica API, but cannot be bound to LangChain chains/agents.
"""
from .retriever import LANGCHAIN_AVAILABLE, SemanticaRetriever
from .tools import SemanticaDecisionTool, SemanticaKGTool
from .vectorstore import SemanticaVectorStore
__all__ = [
"SemanticaRetriever",
"SemanticaVectorStore",
"SemanticaKGTool",
"SemanticaDecisionTool",
"LANGCHAIN_AVAILABLE",
]
__version__ = "0.1.0"
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"""
SemanticaRetriever — LangChain ``BaseRetriever`` with multi-hop GraphRAG.
Hybrid search seeds the retrieval, then graph edges are walked for ``hops``
steps so results go beyond flat vector similarity.
"""
from __future__ import annotations
from typing import Any, Dict, List, Optional, Tuple
from semantica.utils.logging import get_logger
logger = get_logger(__name__)
# ---------------------------------------------------------------------------
# Optional: LangChain core
# ---------------------------------------------------------------------------
LANGCHAIN_AVAILABLE = False
LANGCHAIN_IMPORT_ERROR: Optional[str] = None
_BaseRetriever: Any = object
_Document: Any = None
def _get_document(**kwargs: Any) -> Any:
"""Instantiate a langchain Document lazily (keeps the import optional)."""
if _Document is None: # pragma: no cover - exercised only with langchain
raise RuntimeError(LANGCHAIN_IMPORT_ERROR or "langchain-core not installed")
return _Document(**kwargs)
try:
from langchain_core.documents import Document as _Document # type: ignore
from langchain_core.retrievers import (
BaseRetriever as _BaseRetriever, # type: ignore
)
LANGCHAIN_AVAILABLE = True
except ImportError: # pragma: no cover - exercised only without langchain
LANGCHAIN_IMPORT_ERROR = (
"langchain-core is not installed. Install with: pip install langchain-core"
)
logger.debug(LANGCHAIN_IMPORT_ERROR)
def _hit_layers(hit: Dict[str, Any]) -> Tuple[Dict[str, Any], Dict[str, Any]]:
"""Nested HybridSearch metadata and ContextGraph.query node, if present."""
metadata = hit.get("metadata") if isinstance(hit.get("metadata"), dict) else {}
node = hit.get("node") if isinstance(hit.get("node"), dict) else {}
return metadata, node
def _hit_id(hit: Dict[str, Any]) -> Optional[str]:
"""Graph node id, preferring metadata over a HybridSearch vector id."""
metadata, node = _hit_layers(hit)
return (
hit.get("node_id")
or metadata.get("node_id")
or node.get("id")
or node.get("node_id")
or hit.get("id")
)
def _hit_content(hit: Dict[str, Any], fallback: str = "") -> str:
metadata, node = _hit_layers(hit)
props = node.get("properties") if isinstance(node.get("properties"), dict) else {}
return (
hit.get("content")
or hit.get("text")
or metadata.get("content")
or metadata.get("text")
or props.get("content")
or fallback
)
def _hit_type(hit: Dict[str, Any]) -> str:
metadata, node = _hit_layers(hit)
return (
hit.get("node_type")
or hit.get("type")
or metadata.get("node_type")
or metadata.get("type")
or node.get("type")
or node.get("node_type")
or "node"
)
def _hit_score(hit: Dict[str, Any], default: float = 1.0) -> float:
return float(hit.get("score") if hit.get("score") is not None else hit.get("distance") or default)
class SemanticaRetriever(_BaseRetriever): # type: ignore[misc]
"""GraphRAG-style retriever over a Semantica ``ContextGraph``.
Args:
graph: A semantica.context.ContextGraph instance.
hybrid: A semantica.vector_store.HybridSearch instance used to seed
retrieval. If omitted, a best-effort keyword search on the graph
is used.
hops: Number of graph-edge expansion hops (default 2).
top_k: Number of seed hits (default 10).
"""
graph: Any
hybrid: Any = None
hops: int = 2
top_k: int = 10
def __init__(
self,
graph: Any,
hybrid: Any = None,
hops: int = 2,
top_k: int = 10,
**kwargs: Any,
) -> None:
"""Explicit init so the retriever works with and without langchain."""
if LANGCHAIN_AVAILABLE:
# BaseRetriever is a Pydantic model: pass the declared fields
# through so validation succeeds.
super().__init__(
graph=graph,
hybrid=hybrid,
hops=hops,
top_k=top_k,
**kwargs,
)
else:
# Without langchain-core, BaseRetriever is a plain object
super().__init__() # type: ignore[call-arg]
self.graph = graph
self.hybrid = hybrid
self.hops = hops
self.top_k = top_k
def _get_relevant_documents(self, query: str, **kwargs: Any) -> List[Any]:
"""LangChain BaseRetriever entry point."""
seed = self._seed_results(query)
if not seed:
return []
# Expand each seed node through the graph
expanded: Dict[str, Dict[str, Any]] = {}
for hit in seed:
node_id = _hit_id(hit)
if not node_id:
continue
metadata, _ = _hit_layers(hit)
expanded[node_id] = {
"content": _hit_content(hit, fallback=str(node_id)),
"node_type": _hit_type(hit),
"score": _hit_score(hit),
"metadata": metadata,
}
try:
neighbors = self.graph.get_neighbors(node_id, hops=self.hops)
for neighbor in neighbors:
nid = neighbor.get("node_id") or neighbor.get("id")
if nid and nid not in expanded:
expanded[nid] = {
"content": neighbor.get("content")
or neighbor.get("text")
or neighbor.get("name")
or str(nid),
"node_type": neighbor.get("node_type")
or neighbor.get("type")
or "node",
"score": float(neighbor.get("weight") or 0.5),
"metadata": {},
}
except Exception as exc: # graph expansion is best-effort
logger.debug("graph expansion failed for %s: %s", node_id, exc)
# Order: seed hits first (they have real scores), then neighbors.
# Keep a deterministic id->payload list (sets are unordered — see Qodo).
ordered_pairs: List[tuple] = []
seen_ids = set()
for hit in seed:
nid = _hit_id(hit)
if nid and nid in expanded and nid not in seen_ids:
ordered_pairs.append((nid, expanded[nid]))
seen_ids.add(nid)
for nid, item in expanded.items():
if nid not in seen_ids:
ordered_pairs.append((nid, item))
seen_ids.add(nid)
return [
_get_document(
page_content=item["content"],
metadata={
**item["metadata"],
"node_id": nid,
"node_type": item["node_type"],
"score": item["score"],
},
)
for nid, item in ordered_pairs
]
def _seed_results(self, query: str) -> List[Dict[str, Any]]:
"""Get seed results from hybrid search or a graph keyword scan."""
if self.hybrid is not None:
try:
return self.hybrid.search(query, k=self.top_k)
except Exception as exc:
logger.debug("hybrid search failed, falling back: %s", exc)
# Best-effort keyword scan over graph nodes (ContextGraph.query)
try:
return self.graph.query(query, limit=self.top_k)
except Exception:
return []
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"""
SemanticaKGTool / SemanticaDecisionTool — LangChain ``BaseTool`` adapters
for LangChain / LangGraph agents.
"""
from __future__ import annotations
import json
from typing import Any, Optional, Type
from pydantic import BaseModel, ConfigDict, Field
from semantica.utils.logging import get_logger
logger = get_logger(__name__)
# ---------------------------------------------------------------------------
# Optional: LangChain core
# ---------------------------------------------------------------------------
LANGCHAIN_AVAILABLE = False
LANGCHAIN_IMPORT_ERROR: Optional[str] = None
_BaseTool: Any = object
try:
from langchain_core.tools import BaseTool as _BaseTool # type: ignore
LANGCHAIN_AVAILABLE = True
except ImportError: # pragma: no cover
LANGCHAIN_IMPORT_ERROR = (
"langchain-core is not installed. Install with: pip install langchain-core"
)
logger.debug(LANGCHAIN_IMPORT_ERROR)
def _json(payload: Any) -> str:
return json.dumps(payload, default=str, ensure_ascii=False)
class QueryGraphInput(BaseModel):
query: str = Field(..., description="Natural-language or keyword graph query")
limit: int = Field(10, description="Maximum matching nodes to return")
class QueryDecisionsInput(BaseModel):
category: str = Field(
"",
description="Keyword to search recorded decisions; empty returns insights",
)
limit: int = Field(10, description="Maximum results when searching by keyword")
class SemanticaKGTool(_BaseTool): # type: ignore[misc]
"""LangChain tool for querying a Semantica ``ContextGraph``.
Args:
graph: A semantica.context.ContextGraph instance.
Example:
>>> tool = SemanticaKGTool(graph)
>>> agent = create_react_agent(model, tools=[tool])
"""
model_config = ConfigDict(arbitrary_types_allowed=True)
name: str = "semantica_query_graph"
description: str = (
"Query Semantica's shared context graph with a natural-language "
"keyword query. Returns matching entities and relationships."
)
args_schema: Type[BaseModel] = QueryGraphInput
graph: Any = None
def __init__(self, graph: Any = None, **kwargs: Any) -> None:
if LANGCHAIN_AVAILABLE:
super().__init__(graph=graph, **kwargs)
else:
super().__init__()
self.graph = graph
def build(self) -> Any:
"""Return this tool, or None if langchain-core is missing."""
return self if LANGCHAIN_AVAILABLE else None
def _run(self, query: str, limit: int = 10, **kwargs: Any) -> str:
try:
return _json(self.graph.query(query, limit=limit))
except Exception as exc:
return _json({"error": str(exc)})
async def _arun(self, query: str, limit: int = 10, **kwargs: Any) -> str:
return self._run(query, limit=limit)
class SemanticaDecisionTool(_BaseTool): # type: ignore[misc]
"""LangChain tool for searching Semantica's recorded decision log.
Args:
graph: A semantica.context.ContextGraph instance.
"""
model_config = ConfigDict(arbitrary_types_allowed=True)
name: str = "semantica_query_decisions"
description: str = (
"Search Semantica's recorded decision log with a keyword query. "
"Returns decisions, rationale, and context."
)
args_schema: Type[BaseModel] = QueryDecisionsInput
graph: Any = None
def __init__(self, graph: Any = None, **kwargs: Any) -> None:
if LANGCHAIN_AVAILABLE:
super().__init__(graph=graph, **kwargs)
else:
super().__init__()
self.graph = graph
def build(self) -> Any:
"""Return this tool, or None if langchain-core is missing."""
return self if LANGCHAIN_AVAILABLE else None
def _run(self, category: str = "", limit: int = 10, **kwargs: Any) -> str:
try:
if category:
return _json(self.graph.query(category, limit=limit))
return _json(self.graph.get_decision_insights())
except Exception as exc:
return _json({"error": str(exc)})
async def _arun(self, category: str = "", limit: int = 10, **kwargs: Any) -> str:
return self._run(category=category, limit=limit)
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"""
SemanticaVectorStore — LangChain ``VectorStore`` adapter over Semantica's
hybrid search (``semantica.vector_store.HybridSearch``).
"""
from __future__ import annotations
from typing import Any, Dict, Iterable, List, Optional
from semantica.utils.logging import get_logger
from .retriever import _hit_content, _hit_id, _hit_score, _hit_type, _hit_layers
logger = get_logger(__name__)
# ---------------------------------------------------------------------------
# Optional: LangChain core
# ---------------------------------------------------------------------------
LANGCHAIN_AVAILABLE = False
LANGCHAIN_IMPORT_ERROR: Optional[str] = None
_VectorStoreBase: Any = object
_Document: Any = None
def _make_document(**kwargs: Any) -> Any:
if _Document is None: # pragma: no cover
raise RuntimeError(LANGCHAIN_IMPORT_ERROR or "langchain-core not installed")
return _Document(**kwargs)
try:
from langchain_core.documents import Document as _Document # type: ignore
from langchain_core.vectorstores import (
VectorStore as _VectorStoreBase, # type: ignore
)
LANGCHAIN_AVAILABLE = True
except ImportError: # pragma: no cover
LANGCHAIN_IMPORT_ERROR = (
"langchain-core is not installed. Install with: pip install langchain-core"
)
logger.debug(LANGCHAIN_IMPORT_ERROR)
def _document_from_hit(hit: Dict[str, Any], include_score: bool = True) -> Any:
metadata, _ = _hit_layers(hit)
node_id = _hit_id(hit)
doc_meta = {
**metadata,
"node_id": node_id,
"node_type": _hit_type(hit),
}
if include_score:
doc_meta["score"] = _hit_score(hit, default=0.0)
return _make_document(
page_content=_hit_content(hit),
metadata=doc_meta,
)
class SemanticaVectorStore(_VectorStoreBase): # type: ignore[misc]
"""Wrap Semantica hybrid search as a LangChain ``VectorStore``.
Args:
hybrid: A semantica.vector_store.HybridSearch instance.
vector_store: Optional Semantica vector store passed through to
``HybridSearch.add_texts``.
"""
hybrid: Any
vector_store: Any = None
def __init__(self, hybrid: Any, vector_store: Any = None, **kwargs: Any) -> None:
if LANGCHAIN_AVAILABLE:
super().__init__(**kwargs)
else:
super().__init__()
self.hybrid = hybrid
self.vector_store = vector_store
# -- required VectorStore API ------------------------------------------
def add_texts(
self,
texts: Iterable[str],
metadatas: Optional[List[Dict[str, Any]]] = None,
**kwargs: Any,
) -> List[str]:
"""Embed and store texts; return the generated IDs.
Delegates to the Semantica ``VectorStore.add_documents`` backing the
HybridSearch instance (or to ``hybrid.vector_store`` if provided).
"""
if self.vector_store is not None:
return self.vector_store.add_documents(
list(texts), metadata=metadatas, **kwargs
)
vs = getattr(self.hybrid, "vector_store", None)
if vs is not None and hasattr(vs, "add_documents"):
return vs.add_documents(list(texts), metadata=metadatas, **kwargs)
raise ValueError(
"SemanticaVectorStore requires a Semantica vector store with "
"add_documents (pass vector_store=... to the HybridSearch or to "
"SemanticaVectorStore)"
)
def similarity_search(self, query: str, k: int = 4, **kwargs: Any) -> List[Any]:
"""Return documents most similar to the query."""
return [_document_from_hit(hit) for hit in self.hybrid.search(query, k=k)]
def similarity_search_with_score(
self, query: str, k: int = 4, **kwargs: Any
) -> List[Any]:
"""Return (document, score) pairs."""
return [
(
_document_from_hit(hit, include_score=False),
_hit_score(hit, default=0.0),
)
for hit in self.hybrid.search(query, k=k)
]
@classmethod
def from_texts(
cls,
texts: List[str],
embedding: Any = None,
metadatas: Optional[List[Dict[str, Any]]] = None,
**kwargs: Any,
) -> "SemanticaVectorStore":
"""Build a store from a list of texts (LangChain convention).
Requires a pre-configured ``hybrid`` instance passed via kwargs.
"""
hybrid = kwargs.pop("hybrid", None)
if hybrid is None:
raise ValueError(
"SemanticaVectorStore.from_texts requires a 'hybrid' "
"HybridSearch instance as a keyword argument"
)
store = cls(hybrid=hybrid, **kwargs)
store.add_texts(texts, metadatas=metadatas)
return store