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Basic usage

from agent_sentinel import guarded_action

@guarded_action(name="search_web", cost_usd=0.02, tags=["tool", "search"])
def search_web(query: str) -> dict:
    return {"results": ["..."], "query": query}
Calling search_web(...) will:
  • Measure duration
  • Record inputs/outputs
  • Append a ledger entry

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Async functions

from agent_sentinel import guarded_action

@guarded_action(name="call_llm", cost_usd=0.05, tags=["llm"])
async def call_llm(prompt: str) -> str:
    return "..."

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Exceptions

Agent Sentinel does not swallow your exceptions. If your function raises, the exception propagates normally — the SDK records the action as outcome="error" and logs the error string.

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Fail-open vs fail-closed

  • Fail-open: ledger writes and remote sync should never crash your agent.
  • Fail-closed: policy violations intentionally raise before execution (see Policies).

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Replay mode integration

If replay mode is active, decorated actions return recorded outputs instead of executing (and are logged with outcome="replayed"). See Replay.