> ## Documentation Index
> Fetch the complete documentation index at: https://docs.verlon.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Update a gate

> **Use when:** caller wants to change a gate's configuration (model, fallbacks, parameters, system prompt, allowed overrides)

Partial update of a gate's configuration. Validates model references at the API boundary; reject unknown models in `fallbackModels` and `modelPool`, but only when those fields are being explicitly set (so edits to other fields on a gate with pre-existing typo'd fallbacks aren't blocked). Triggers history + activity log entries when significant fields change.



## OpenAPI

````yaml /api-reference/openapi.json patch /v1/gates/:id
openapi: 3.1.0
info:
  title: Verlon AI API
  version: 1.0.0
  description: >-
    Verlon AI is the managed AI infrastructure platform for developers building
    LLM-powered apps and agents. Beyond routing requests across providers,
    Verlon continuously evaluates response quality, runs experiments against
    live traffic, and automatically tunes gate configurations — so your platform
    doesn't just serve traffic, it learns from it.


    **Coding agents:** authentication, error semantics, gate concepts, and
    integration conventions are documented at https://verlon.ai/AGENTS.md — read
    that document first if you have not already. It is the canonical
    agent-facing contract; this specification is the canonical endpoint
    reference. Both are authoritative for their respective scopes.
  contact:
    name: Verlon AI
    url: https://verlon.ai
  license:
    name: Proprietary
servers:
  - url: https://api.verlon.ai
    description: Production
security:
  - bearerAuth: []
paths:
  /v1/gates/:id:
    patch:
      tags:
        - Gates
      summary: Update a gate
      description: >-
        **Use when:** caller wants to change a gate's configuration (model,
        fallbacks, parameters, system prompt, allowed overrides)


        Partial update of a gate's configuration. Validates model references at
        the API boundary; reject unknown models in `fallbackModels` and
        `modelPool`, but only when those fields are being explicitly set (so
        edits to other fields on a gate with pre-existing typo'd fallbacks
        aren't blocked). Triggers history + activity log entries when
        significant fields change.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties: {}
      responses:
        '200':
          description: >-
            Gate updated; response includes the updated gate, `hasChanges`, and
            `changedFields` array.
        '400':
          description: >-
            Validation error — unsupported model, invalid range, malformed
            quality floor, etc.
        '401':
          description: Missing or invalid Bearer credentials
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '404':
          description: Gate not found or not owned by the caller.
        '500':
          description: Internal server error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      security:
        - bearerAuth: []
components:
  schemas:
    ErrorResponse:
      type: object
      properties:
        error:
          type: string
          description: Stable error code (e.g. `invalid_request`)
        message:
          type: string
          description: Human-readable error message
        details: {}
      required:
        - error
        - message
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API Key
      description: >-
        Verlon API key (newly minted keys are prefixed `sk-vrln-`; legacy
        `verlon_*` and `layer_*` keys from prior prefix migrations continue to
        validate). Generated from the dashboard under Settings → API Keys, or
        via `verlon key create` in the CLI.

````