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LangGraph with RunVouch

LangGraph gives you cycles by design. A cycle that never converges, on a nightly schedule, is a bill. LangSmith shows you the trace afterwards; RunVouch stops the run when it crosses the cap.

How it runs on LangGraph

Around the graph invocation with the Python client; report each tool node call with run.tool() so identical inputs are detected as a retry storm.

Store the key

An environment variable wherever the graph runs (cron, container, Lambda).

Wrap the job

import runvouch
from graph import app   # your compiled StateGraph

runvouch.agent("research-digest", cadence_s=86400, cap_run_cost=2, evidence_required=True)

with runvouch.vouch("research-digest", evidence=lambda: {"digest": len(result["digest"]) > 200}) as run:
    result = None
    for event in app.stream({"topic": "..."}, stream_mode="updates"):
        for node, update in event.items():
            run.tool(node, update.get("tool_input", {}), cost=update.get("cost", 0))
    result = app.get_state(config).values

rv fails open: if RunVouch is unreachable the job still runs and you get one warning line.

Register the cadence and caps

rv agent nightly-report --cadence 24h --grace 30m --max-runtime 1h --evidence --cap-run-cost 2

Register the agent once, from anywhere with the key. Cadence is what turns a schedule that stopped into an alert; --evidence makes a run without evidence a failure; the caps pause the agent when it overspends.

What goes silent on LangGraph

• Cycles with a high recursion limit look like progress; 40 identical tool inputs in one run is RETRY_STORM.
• A graph that ends with an empty final state is a completed run; evidence says whether the digest exists.
• Nothing in LangGraph knows the schedule; MISSED comes from the agent's cadence.

What RunVouch detects

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