--- id: DOM-PFM-ELG-002 title: Rule Use realises: CON-PFM-ELG-002 product_area: platform module: eligibility revision: 1 status: draft design_intent: confirmed origin: >- Eligibility Engine architecture approved by Andrew 2026-10-17 (D-08 fail policy, D-27 private rules, D-31 plans for in-process evaluation, recorded in PLAT-M11 "Decisions"); PLAT-M11 plan D4 (refuse unless forced) and D6 (the product card), 2026-10-21 implementation_evidence: observed source_sha: services-platform: ad3f6a6582843008ed0f5a17b131878d15829af1 react-console: baf6dae382d6f41dce976c7f848667ccc37e076f owned_by: SVC-PFM-ELG-eligibility readable_by: [] lifecycle: STATE-PFM-ELG-003 custom_fields: none identity: >- A generated use identity connects one consumer application, purpose and record reference to a rule. The workspace uniqueness constraint prevents duplicating that same connection. attributes: - name: consumer kind: reference required: true computed: false notes: >- Names the consumer application, declared purpose and its record reference, with a readable usage label. - name: rule kind: reference required: true computed: false notes: Identifies the definition evaluated by this connection. - name: version choice kind: enum required: true computed: false notes: >- Either follows the published release effective on the evaluation day or pins a published or superseded release. - name: parameters kind: collection required: true computed: false notes: >- Supplies declared parameter values with type, collection, choice and bound validation; required values without defaults must be supplied. - name: uncertainty policy kind: enum required: true computed: false notes: >- Selects closed, open-with-review or defer behavior, using the purpose default unless overridden. - name: availability kind: enum required: true computed: false notes: Stores active or suspended availability. - name: evaluation plan kind: computed required: false computed: true notes: >- Provides a compiled plan with reporting statements, provider steps and SQL-only form, keyed by input fingerprint. Optional caches sit above its durable copy; the plan version tag supports not-modified replies. - name: version read kind: number required: true computed: false notes: Carries the current record version required by change requests. relationships: - to: DOM-PFM-ELG-001 cardinality: Multiple uses can select one definition. ownership: The use stores the definition link and active connections block archive. cross_service: false - to: DOM-PFM-ELG-003 cardinality: One use can produce multiple recorded evaluations. ownership: Decision history survives deletion of its originating use. cross_service: false invariants: - id: INV-DOM-PFM-ELG-002-01 statement: A workspace cannot store the same consumer-to-rule connection twice. enforced_at: - database provenance: observed source: >- services-platform:modules/eligibility/db/eligibility-bindings.table.ts:eligibility_bindings_consumer_uq - id: INV-DOM-PFM-ELG-002-02 statement: Pinned uses require a release number; following uses must omit it. enforced_at: - service - database provenance: observed source: >- services-platform:modules/eligibility/db/eligibility-bindings.table.ts:eligibility_bindings_pin_check - id: INV-DOM-PFM-ELG-002-03 statement: >- A new or changed pin must select a published or superseded release belonging to this rule. enforced_at: - service provenance: observed source: >- services-platform:modules/eligibility/lifecycle.ts:bindingCompatibilityRefusal - id: INV-DOM-PFM-ELG-002-04 statement: >- Creation and change check compatibility with the purpose and selected expression, then recheck publication changes while holding the rule lock. enforced_at: - service provenance: observed source: >- services-platform:modules/eligibility/services/bindings/consumer-bindings.ts:bindDefinition - id: INV-DOM-PFM-ELG-002-05 statement: Evaluation rejects suspended uses instead of reporting them ineligible. enforced_at: - service - database provenance: observed source: >- services-platform:modules/eligibility/services/evaluate/hosted-evaluate.ts:prepareEvaluations - id: INV-DOM-PFM-ELG-002-06 statement: >- Removing a use deletes associated plans without deleting its retained decision history. enforced_at: - service - database provenance: observed source: >- services-platform:modules/eligibility/services/bindings/consumer-bindings.ts:unbind - id: INV-DOM-PFM-ELG-002-07 statement: >- Console plan responses omit internal statements, providers and explanation templates; service consumers receive the full plan. enforced_at: - service provenance: observed source: >- services-platform:modules/eligibility/services/compile/binding-plan.ts:redactBindingPlan physical: - platform.eligibility_bindings - platform.eligibility_plans evidence: - >- services-platform at ad3f6a6: db/eligibility-bindings.table.ts, eligibility-plans.table.ts; binding-fit.ts; lifecycle.ts; services/bindings/consumer-bindings.ts; services/compile/plan-cache.ts, binding-plan.ts; aws/api/bindings.routes.ts, eligibility-service.routes.ts; docs/eligibility.md §7.7, §8.3, §10.1. - >- react-console at baf6dae: components/eligibility/embeds/eligibility-card.tsx, use-consumer-binding.ts. --- # Rule Use ## What It Models A rule use applies shared qualification logic to a particular application decision. ## Identity and Attributes It combines the consumer reference, release selection, parameters, uncertainty policy and availability. ## Relationships Eligibility owns the connection; the consuming application retains its own business record. ## Invariants Compatibility is a service check, while uniqueness and pin shape also have database constraints. ## How It Is Stored and Shared Eligibility stores uses and plans. Applications call its evaluation and binding contracts; neither record declares custom fields. ## Open Design Questions Changing products between rules is not atomic in the current browser orchestration, and ownership checks on the consumer record remain a planning disagreement.