Stochastic-Deterministic Boundary (SDB)
Formalize the seam between an LLM proposal and a system action as a four-part contract — proposer, verifier, commit step, reject signal — so the contract itself, not the agent's good intent, gates side-effects.
Problem
Without a named contract at the boundary, validation is implicit and inconsistent. An LLM proposes something; somewhere downstream it commits; somewhere there may be a check. Audit cannot say 'every action passed verification' because verification is not architecturally enforced. The team has no shared vocabulary for the seam where stochastic generation becomes deterministic effect.
Solution
Treat the SDB as the load-bearing primitive of the runtime. Define the four parts explicitly per action class: Proposer is the LLM call that emits a candidate action; Verifier is a deterministic function that returns accept/reject with reason; Commit is the side-effect that fires only on accept; Reject is a structured signal (typed error, retry hint, escalation token) that downstream systems can react to. Audit reports group by SDB instance. Pair with supervisor-plus-gate, policy-as-code-gate, eval-as-contract.
When to use
- Production runtime where LLM outputs drive consequential actions.
- Team needs shared vocabulary across multiple action classes.
- Audit requires demonstrable per-action validation.
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