> ## Documentation Index > Fetch the complete documentation index at: https://docs.moonbounce.ai/llms.txt > Use this file to discover all available pages before exploring further. # Choose the model a decision runs on > Sets the model a decision runs on in the calling key's environment, for every question, as a new revision of the setting. Evaluations run on it from the next call, and a switch also moves imported examples, previews and suggestions. The weights and cut points in a structure were set against one model's answers and are not checked against another's, so switch with a test key first and backtest there: each environment has its own setting. Always 200: `changed` is false, and no revision is written, when the body matches the current revision. A model this deployment does not offer is 400 CAPABILITY_UNSUPPORTED. 404 DECISION_UNKNOWN when the decision doesn't exist. An Idempotency-Key covers the body as sent, so retry with the same body; it replays even if the model's configuration changed. ## OpenAPI ````yaml /openapi.json put /v1/decisions/{decision_id}/model openapi: 3.1.0 info: title: Moonbounce Decisions API version: 0.0.0 description: >- Moonbounce decisions: evaluate an item's state against a decision structure (System One questions, attributes you supply and aggregations over both), record feedback and import labeled examples, review a ranked queue, and improve the structure through suggestions that ship as code diffs, each with a preview (backtest) and an evidence label. **Authentication.** Send an API key as `Authorization: Bearer ` on every operation except `GET /health` and `POST /v1/validate`. Call the API from a server, never a browser: a key must not reach one, and the API sends no CORS headers. A key belongs to one organization and one environment: production, or test for a key with the `env:test` permission. Test traffic never counts as production traffic. **Requests.** JSON bodies (`Content-Type: application/json`) of at most 1 MB, parsed strictly: duplicate keys, lone surrogates, integers outside ±(2^53 - 1), `__proto__` keys, U+0000 and nesting deeper than 64 are a 400. **Retries.** Send an `Idempotency-Key` on every POST under /v1 that takes one (all but `POST /v1/validate` and `POST /v1/review/items/fill`, whose retry is another fill within the day's budget). Keep it for the request's retries. The same key with the same request returns the first stored result, marked `Idempotent-Replayed: true`, for 24 hours (410 if that result was since deleted); with another request it is 422 IDEMPOTENCY_KEY_REUSED. Keys are scoped to the organization and environment across every operation, so use a fresh key per request. A request that failed before its result was stored runs again when retried. 429 and 503 under /v1 may carry `Retry-After` (seconds); a daily QUOTA_EXCEEDED cap instead names its reset time. **Errors.** Every error under /v1 is `{"error": {"type", "message", "reason"?, "param"?, "details"?}}` (ErrorBody); `GET /health` answers its own shape. Every response carries a `Request-Id` header. Rate limits apply per key, and per client IP for requests without a valid key; a 429 RATE_LIMITED carries `Retry-After`. servers: - url: https://api.moonbounce.ai description: Production security: [] paths: /v1/decisions/{decision_id}/model: put: tags: - models summary: Choose the model a decision runs on description: >- Sets the model a decision runs on in the calling key's environment, for every question, as a new revision of the setting. Evaluations run on it from the next call, and a switch also moves imported examples, previews and suggestions. The weights and cut points in a structure were set against one model's answers and are not checked against another's, so switch with a test key first and backtest there: each environment has its own setting. Always 200: `changed` is false, and no revision is written, when the body matches the current revision. A model this deployment does not offer is 400 CAPABILITY_UNSUPPORTED. 404 DECISION_UNKNOWN when the decision doesn't exist. An Idempotency-Key covers the body as sent, so retry with the same body; it replays even if the model's configuration changed. operationId: setModel parameters: - schema: $ref: '#/components/schemas/DecisionId' required: true description: >- A name you choose for this decision, such as `refund-exception`: a lowercase letter, then up to 127 of `a-z 0-9 _ . -`. Unique in your organization and shared by its test and production keys. The first registration or evaluation under a new one creates the decision. name: decision_id in: path - schema: type: string minLength: 1 maxLength: 255 pattern: ^[\x20-\x7e]+$ description: >- Makes a retry safe. For 24 hours, the same key with the same request returns the first stored result (with Idempotent-Replayed: true); the same key with a different request is a 422 IDEMPOTENCY_KEY_REUSED. Keys are scoped to the organization and environment across every operation, so use a fresh key per request. A request that failed before its result was stored runs again when retried with its key. required: false description: >- Makes a retry safe. For 24 hours, the same key with the same request returns the first stored result (with Idempotent-Replayed: true); the same key with a different request is a 422 IDEMPOTENCY_KEY_REUSED. Keys are scoped to the organization and environment across every operation, so use a fresh key per request. A request that failed before its result was stored runs again when retried with its key. name: idempotency-key in: header requestBody: required: true content: application/json: examples: clef: summary: Move the decision to Clef in the key's environment value: model: '@cf/cloudflare/clef' schema: $ref: '#/components/schemas/ModelSettingWrite' responses: '200': description: The setting, changed or not headers: Idempotent-Replayed: schema: type: string enum: - 'true' description: >- Present and `true` when this is the stored result of an earlier request with the same Idempotency-Key. required: false description: >- Present and `true` when this is the stored result of an earlier request with the same Idempotency-Key. content: application/json: examples: changed: summary: A new revision value: decision_id: refund-exception environment: test model: '@cf/cloudflare/clef' pinned: false revision: 2 source: setting created_at: '2026-11-06T16:00:00.000Z' changed: true schema: $ref: '#/components/schemas/ModelSettingWritten' '400': description: 'Invalid request: `param` names the field at fault when one applies' content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '401': description: Missing or invalid API key (reason KEY_INVALID) content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '403': description: The key may not do this content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '404': description: Not found, or not in this key's organization and environment content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '410': description: >- The Idempotency-Key's first result was deleted, so it cannot be replayed content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '413': description: The HTTP body exceeds 1 MB (reason BODY_TOO_LARGE) content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '422': description: >- The request is well formed but cannot be processed (IDEMPOTENCY_KEY_REUSED requires a fresh key; REQUEST_TOO_LARGE requires a smaller request) content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '429': description: >- RATE_LIMITED: retry after Retry-After seconds; QUOTA_EXCEEDED: details.reset_at gives the daily reset time (no Retry-After) headers: Retry-After: schema: type: string description: Seconds to wait before retrying, when waiting helps. required: false description: Seconds to wait before retrying, when waiting helps. content: application/json: schema: $ref: '#/components/schemas/ErrorBody' '503': description: >- Temporarily unavailable, with Retry-After (for example reason AUTH_UNAVAILABLE, ENGINE_UNAVAILABLE or STORE_UNAVAILABLE): retry with the same Idempotency-Key headers: Retry-After: schema: type: string description: Seconds to wait before retrying, when waiting helps. required: true description: Seconds to wait before retrying, when waiting helps. content: application/json: schema: $ref: '#/components/schemas/ErrorBody' security: - bearerAuth: - decisions:develop components: schemas: DecisionId: type: string pattern: ^[a-z][a-z0-9_.-]{0,127}$ description: >- A name you choose for this decision, such as `refund-exception`: a lowercase letter, then up to 127 of `a-z 0-9 _ . -`. Unique in your organization and shared by its test and production keys. The first registration or evaluation under a new one creates the decision. ModelSettingWrite: type: object properties: model: type: string minLength: 1 maxLength: 128 description: >- A model id from `GET /v1/models`, such as `jev-1.14.0`. `*-latest` and `*-preview` aliases are refused; whether an id fixes the model's behavior is its `pinned` flag. Open: new models are added without a contract change. example: jev-1.14.0 required: - model additionalProperties: false ModelSettingWritten: allOf: - $ref: '#/components/schemas/ModelSetting' - type: object properties: changed: type: boolean description: >- False when the body matched the current revision, so nothing was written. required: - changed ErrorBody: type: object properties: error: type: object properties: type: $ref: '#/components/schemas/ErrorType' reason: type: string pattern: ^[A-Z][A-Z0-9_]+$ description: >- Set where a caller can act on it, one of the reasons in the ErrorReason schema. New reasons may be added: treat an unknown one by the status and `type`. message: type: string description: For people; don't parse it. param: type: string description: >- The request field at fault, as a dotted path (`attribute_values.region`, `claims.1.value`). details: type: object properties: issues: type: array items: $ref: '#/components/schemas/ErrorIssue' additionalProperties: {} required: - type - message additionalProperties: true x-moonbounce-sdk-known-fields: true required: - error additionalProperties: true x-moonbounce-sdk-known-fields: true ModelSetting: type: object properties: decision_id: $ref: '#/components/schemas/DecisionIdOutput' environment: $ref: '#/components/schemas/Environment' model: type: string minLength: 1 maxLength: 128 description: >- A model id from `GET /v1/models`, such as `jev-1.14.0`. `*-latest` and `*-preview` aliases are refused; whether an id fixes the model's behavior is its `pinned` flag. Open: new models are added without a contract change. example: jev-1.14.0 pinned: type: boolean description: >- Whether the model is pinned (see `GET /v1/models`). False when this deployment doesn't offer it. revision: type: - integer - 'null' minimum: 1 description: >- Which edit of the setting this is: 1 for the first stored here, then 2, 3... Evaluations report the one they ran on as `model.revision`. Null when nothing is stored in this environment and the deployment default applies. source: type: string enum: - setting - default description: >- `setting`: a stored revision. `default`: none is stored here, so the deployment default applies. created_at: type: - string - 'null' format: date-time description: When the revision was stored. required: - decision_id - environment - model - pinned - revision - source - created_at ErrorType: type: string enum: - invalid_request - authentication - permission_denied - not_found - conflict - rate_limited - engine_failed - unavailable - internal ErrorIssue: type: object properties: param: type: string code: type: string pattern: ^[A-Z][A-Z0-9_]+$ description: >- Stable, extensible issue code; unknown codes still have a parameter and human-readable message. message: type: string required: - param - code - message additionalProperties: true x-moonbounce-sdk-known-fields: true DecisionIdOutput: type: string pattern: ^[a-z][a-z0-9_.-]{0,127}$ description: >- A name you choose for this decision, such as `refund-exception`: a lowercase letter, then up to 127 of `a-z 0-9 _ . -`. Unique in your organization and shared by its test and production keys. The first registration or evaluation under a new one creates the decision. Environment: type: string enum: - production - test description: >- The environment of the key that made the call: `production` or `test`. Evaluations, feedback, reviews and suggestions are separate per environment; decisions and their versions belong to the whole organization. securitySchemes: bearerAuth: type: http scheme: bearer description: >- An API key, sent as `Authorization: Bearer `. Each operation lists the scope its key needs: `decisions:evaluate` (evaluate and read evaluations), `decisions:feedback` (your app's feedback) or `decisions:develop` (everything else, including owner feedback and the review queue). An operation listing no scope takes any scoped key. A key with no scope, or without the operation's, gets 403 INSUFFICIENT_SCOPE. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.