> ## Documentation Index > Fetch the complete documentation index at: https://juspay-78-sa-banks.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Legacy Decision Gateway > Legacy compatibility route. New integrations should use /decide-gateway. ## OpenAPI ````yaml decision_engine_openapi-specs.json POST /decision_gateway openapi: 3.1.0 info: title: Decision Engine description: >- Open-source payment gateway routing service by Juspay. Selects the optimal payment processor for each transaction in real-time using success-rate scoring, rule-based routing, and elimination logic. ## Authentication This API supports two authentication methods: 1. **JWT Bearer Token** - For dashboard/user sessions - Header: `Authorization: Bearer ` - Obtain via `/auth/login` endpoint 2. **API Key** - For service-to-service/programmatic access - Header: `x-api-key: DE_<64_char_hex>` - Create via `/api-key/create` endpoint Protected endpoints require one of these authentication methods. version: 1.4.0 contact: name: Juspay url: https://github.com/juspay/decision-engine license: name: AGPL-3.0 url: https://www.gnu.org/licenses/agpl-3.0.html servers: - url: http://localhost:8080 description: Local development - url: https://sandbox.hyperswitch.io description: 'Hyperswitch sandbox with x-feature: decision-engine' security: [] tags: - name: Health description: Service liveness, readiness, and diagnostics - name: Auth description: Dashboard auth and merchant selection - name: API Keys description: Service-to-service API key management - name: Gateway Decision description: Core routing decision APIs - name: Score Feedback description: Feed transaction outcomes back to improve SR scoring - name: Merchant Account description: Merchant configuration management - name: Routing Rules description: Euclid declarative routing rules engine - name: Rule Configuration description: Service-level SR/elimination config - name: Config description: Routing key and dimension metadata - name: Analytics description: ClickHouse-backed analytics and audit reads - name: Compatibility description: Legacy compatibility routes - name: Connector Costs - name: Merchant Features - name: Autopilot paths: /decision_gateway: post: tags: - Compatibility summary: Legacy decision gateway description: Legacy compatibility route. New integrations should use /decide-gateway. operationId: legacyDecisionGateway requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/LegacyDeciderRequest' responses: '200': description: Gateway decision result content: application/json: schema: $ref: '#/components/schemas/DecidedGateway' '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/DeciderErrorResponse' security: - BearerAuth: [] - ApiKeyAuth: [] components: schemas: LegacyDeciderRequest: type: object required: - orderReference - orderMetadata - txnDetail - txnCardInfo - merchantAccount properties: orderReference: type: object additionalProperties: true description: >- Full internal order object. `merchantId` inside it identifies the merchant. `udfs` is an ARRAY of strings, not an object, and `id` is an integer. orderMetadata: type: object required: - partitionKey properties: partitionKey: type: - string - 'null' description: Required key. May be null. additionalProperties: true description: >- Full internal order-metadata object. Required. Note: `partitionKey` must be PRESENT in this object (it may be `null`). It is an `Option` field with a custom `deserialize_with` and no `serde(default)`, so serde requires the key even though the value is nullable. txnDetail: type: object required: - partitionKey properties: partitionKey: type: - string - 'null' description: Required key. May be null. additionalProperties: true description: >- Full internal transaction object. Note: `partitionKey` must be PRESENT in this object (it may be `null`). It is an `Option` field with a custom `deserialize_with` and no `serde(default)`, so serde requires the key even though the value is nullable. txnCardInfo: type: object required: - partitionKey properties: partitionKey: type: - string - 'null' description: Required key. May be null. additionalProperties: true description: >- Full internal card/payment-method object. Note: `partitionKey` must be PRESENT in this object (it may be `null`). It is an `Option` field with a custom `deserialize_with` and no `serde(default)`, so serde requires the key even though the value is nullable. merchantAccount: type: object additionalProperties: true description: >- Full internal merchant account object. `gatewaySuccessRateBasedDeciderInput` is a required string - `null` is rejected. txnOfferDetails: type: - array - 'null' items: type: object additionalProperties: true cardToken: type: - string - 'null' txnType: type: - string - 'null' shouldCreateMandate: type: - boolean - 'null' enforceGatewayList: type: - array - 'null' items: type: string example: - stripe - adyen priorityLogicOutput: type: - object - 'null' additionalProperties: true priorityLogicScript: type: - string - 'null' isEdccApplied: type: - boolean - 'null' shouldConsumeResult: type: - boolean - 'null' description: >- Legacy decider payload built from full internal transaction objects. This is NOT the `/decide-gateway` shape - posting that body here is rejected with a 400. `orderMetadata`, `txnDetail` and `txnCardInfo` must each carry a `partitionKey` key (value may be null). DecidedGateway: type: object properties: decided_gateway: type: string example: stripe routing_approach: type: string example: SR_SELECTION_V3_ROUTING description: >- Routing approach used. SR_SELECTION_MULTI_OBJECTIVE indicates the multi-objective post-step promoted a cheaper gateway over the SR head. gateway_priority_map: type: object additionalProperties: type: number example: stripe: 0.94 adyen: 0.87 paypal: 0.72 routing_dimension: type: string routing_dimension_level: type: string reset_approach: type: string is_scheduled_outage: type: boolean is_rust_based_decider: type: boolean debit_routing_output: $ref: '#/components/schemas/DebitRoutingOutput' latency: type: number multi_objective_info: oneOf: - $ref: '#/components/schemas/MultiObjectiveInfo' - type: 'null' description: >- Populated when the multi-objective post-step ran (multi_objective_routing_enabled feature flag or enableMultiObjective request field, outside hedging). Null otherwise. fallback_gateways: type: array items: type: string example: - adyen filter_wise_gateways: type: - object - 'null' priority_logic_tag: type: - string - 'null' priority_logic_output: type: - object - 'null' gateway_mga_id_map: type: - object - 'null' is_dynamic_mga_enabled: type: boolean gateway_before_evaluation: type: - string - 'null' description: >- Gateway the SR head selected before the multi-objective / debit-routing post-step replaced it. DeciderErrorResponse: type: object properties: status: type: string example: '400' error_code: type: string example: DATA_NOT_FOUND error_message: type: string example: merchant iframe preferences not found priority_logic_tag: type: - string - 'null' routing_approach: type: - string - 'null' filter_wise_gateways: type: - object - 'null' error_info: type: object properties: code: type: string example: MERCHANT_IFRAME_PREFERENCES_NOT_FOUND user_message: type: string developer_message: type: string priority_logic_output: type: - object - 'null' is_dynamic_mga_enabled: type: boolean description: Error envelope returned by the gateway-decision routes. DebitRoutingOutput: type: object properties: co_badged_card_networks_info: type: array items: type: object properties: network: type: string example: NYCE saving_percentage: type: number example: 1.2 issuer_country: type: string example: US is_regulated: type: boolean example: false regulated_name: type: - string - 'null' card_type: type: string example: Debit MultiObjectiveInfo: type: object description: >- Present when the multi-objective (cost-aware) post-step ran. Explains why the gateway was picked: the SR head was kept (AUTH_WON) or a higher economic-value PSP was promoted (COST_WON). Economic value is auth rate × settlement value, where settlement value = txn amount − cost of payment processing (acquirer, issuer & network fee). properties: outcome: type: string enum: - COST_WON - AUTH_WON example: COST_WON reason: type: string example: >- Promoted 'adyen' over 'stripe' on expected value — saves 80.00 bps for 3.00pp auth. srHead: oneOf: - $ref: '#/components/schemas/PspSummary' - type: 'null' description: The PSP the SR scorer would have picked. chosen: oneOf: - $ref: '#/components/schemas/PspSummary' - type: 'null' description: The PSP the post-step actually chose. Equals srHead when auth won. costSavedBps: type: - number - 'null' description: >- Fee saved in bps when outcome is COST_WON (srHead.costBps - chosen.costBps). example: 80 qualifiedCount: type: integer description: Number of PSPs that had cost data and were ranked on expected value. example: 3 margin: type: number description: >- Merchant margin (fraction of ticket) applied for this transaction. Configured via the successRate config margin field; defaults to 1.0. example: 0.2 evGapTop2: type: - number - 'null' description: >- Expected-value gap between the top-two EV-ranked PSPs, as a fraction of ticket. Null when fewer than two PSPs had cost data. example: 0.00182 PspSummary: type: object properties: psp: type: string example: adyen authRate: type: number example: 0.91 costBps: type: - number - 'null' example: 100 securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: JWT description: JWT token obtained from /auth/login ApiKeyAuth: type: apiKey in: header name: x-api-key description: API key created via /api-key/create ````