← Knowledge Base

Use this checklist before approving any LLM introduction. It maps to the 4-Level Decision Model and follows the DBJ Enterprise Taxonomy levels: Conceptual, Logical, Physical, Implementation. Every item must be answered “yes” for approval.

Work through the four sections and bring the completed checklist to the Architecture Board.

Capability: <name>

Section 1 — Business Capability (Conceptual Level)

Does this capability genuinely require language reasoning?

  • The capability involves unstructured text, ambiguous intent, or contextual reasoning — Yes / No
  • A deterministic alternative (rules, workflow, search) was evaluated and ruled out — Yes / No
  • Written justification exists for why non-LLM approaches are insufficient — Yes / No

Gate: If a rule-based solution could do the job — stop here. ADR rejected.

Section 2 — Service Design (Logical Level)

Is the LLM architecturally contained?

  • LLM is implemented as a single, isolated service — Yes / No
  • There is a defined input/output contract for the service — Yes / No
  • The LLM does not act as orchestrator, policy engine, or cross-domain decision maker — Yes / No
  • Success metrics are defined (accuracy, error rate, hallucination rate, or equivalent) — Yes / No

Gate: If the LLM is central to the architecture — stop here. The proposal is rejected: do not proceed, do not submit to the Architecture Board. Redesign so the LLM is a peripheral service, then restart the checklist.

Section 3 — Operations (Physical Level)

Is production readiness defined?

  • Monthly cost projection is documented, including scaling behavior — Yes / No
  • Response time target is defined — Yes / No
  • Availability target is defined — Yes / No
  • Monitoring plan is in place — Yes / No
  • Fallback behavior is defined (what happens when the LLM fails or returns unusable output) — Yes / No

Gate: If failure mode is undefined — stop here. ADR rejected.

Section 4 — Implementation (Implementation Level)

Can the LLM be removed or replaced cleanly?

  • The model can be swapped without rewriting domain logic — Yes / No
  • No vendor API leaks into core business code — Yes / No
  • Business rules exist in code, not in prompts — Yes / No
  • An anti-corruption layer separates the LLM from the rest of the system — Yes / No

Gate: If removing the LLM would collapse the system — stop here. ADR rejected.

Approval Condition

All four sections must pass. No exceptions.

Semantic necessity
AND bounded service
AND operational readiness
AND replaceability

Any failed gate = architectural violation. Redesign before resubmitting.

Reference: Fred Brooks — Second-System Effect