Fallback Is the Contract

An LLM-backed agent runs first; on failure or timeout a deterministic rule engine guarantees a finalised outcome

Fallback Is the Contract An LLM-backed agent runs first; on failure or timeout a deterministic rule engine guarantees a finalised outcome 01 / Case lifecycle 02 / Deterministic fallback 03 / Outcomes Received · case opens · Case lifecycle · entry 01 Received case opens entry Enrich · gather context · Case lifecycle 02 Enrich gather context LLM Agent · primary attempt · Case lifecycle · model 03 LLM Agent primary attempt model Verify · output valid? · Case lifecycle · gate 04 Verify output valid? gate Finalised · guaranteed exit · Case lifecycle · done 05 Finalised guaranteed exit done Rule Fallback · deterministic engine · Deterministic fallback · no model Rule Fallback deterministic engine no model fail / timeout deterministic exit Legend active state waiting terminal success failure / exit

Primary Path

  • • The LLM-backed agent runs first on every case
  • • A verify gate confirms the model output before finalising
  • • Finalised is a single guaranteed terminal state

Fallback Contract

  • • Any failure or timeout diverts to the rule engine
  • • The deterministic fallback needs no model to run
  • • Every case still lands on the same finalised state

Why It Matters

  • • Fallback, not best-effort, is the reliability contract
  • • The case can never hang in a non-terminal state
  • • Determinism bounds worst-case latency and cost

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