verificate-langchain

A veto gate for AI-written code in LangChain / LangGraph. Your agent writes code; Verificate runs it through 17 deterministic reality gates (mock/placeholder veto, invented-API checks, false-completion detection) plus a frontier-model review, and can veto. An agent that ships confident-but-wrong code loses its user's trust — this is the safety net that keeps it shipping.

pip install verificate-langchain

25 free validations per machine — no signup, no token. After that, pass a token (30-day trial, no card: https://verificate.ai/auth/signup).

One-shot check

from verificate_langchain import validate

v = await validate("def refund(order_id, amount):\n    pass  # TODO real refund")
print(v.approved)     # False — the mock refund path is vetoed
print(v.findings)     # ['[code_reality_gate] Placeholder detected ...', ...]

Verdict is truthy iff approved, so if await validate(code): ship(code) reads naturally.

As a LangGraph guardrail node

from verificate_langchain import VerificateGuardrail
from langgraph.graph import StateGraph, START, END

gate = VerificateGuardrail(max_attempts=3)           # optional token=...

g = StateGraph(dict)
g.add_node("write", write_code)                       # your codegen node, sets state["code"]
g.add_node("gate", gate.node)                         # sets state["verdict"] / ["findings"]
g.add_edge(START, "write")
g.add_edge("write", "gate")
g.add_conditional_edges("gate", gate.route, {"fix": "write", "done": END, "give_up": END})
app = g.compile()

The output must pass through the gate node — the veto is structural, not an optional tool call the agent can skip under pressure.

Load the raw tools

from verificate_langchain import load_verificate_tools

tools = await load_verificate_tools()   # validate_ai_output, validate_plan, analyze_code, generate_code
agent = create_react_agent(model, tools + your_other_tools)

What it catches (real, verbatim)

"N+1 synchronous API calls … 100 sequential HTTP roundtrips … will trigger Stripe rate limiting" · "stripe.Inventory is not a valid Stripe SDK resource" · "Stripe API requires integer cents"

Read-only: code is analyzed, never executed, never trained on. https://verificate.ai/privacy

Uses the official langchain-mcp-adapters against the hosted Verificate MCP server. All clients + one-click installs: https://github.com/Verificate-Dev/verificate-mcp-quickstart