openapi: 3.1.0
info:
  title: EvolutionaryScale Forge ESM Cambrian API
  description: >
    Hosted inference API for the ESM Cambrian (ESM C) protein representation
    learning family. ESM C is a drop-in replacement for ESM2 with comparable
    or better accuracy at substantially reduced memory footprint. Provides
    encode and logits operations for sequence embedding workflows. Available
    in 300M, 600M, and 6B parameter checkpoints.
  version: 2024-12-01
  contact:
    name: EvolutionaryScale Forge
    url: https://forge.evolutionaryscale.ai
  license:
    name: Cambrian Inference Clickthrough License Agreement
    url: https://www.evolutionaryscale.ai/policies/cambrian-inference-clickthrough-license-agreement
servers:
  - url: https://forge.evolutionaryscale.ai
    description: EvolutionaryScale Forge Production
security:
  - BearerAuth: []
tags:
  - name: Embeddings
    description: Sequence-only tokenization and representation extraction.
  - name: Sampling
    description: Per-residue logits and hidden state retrieval.
paths:
  /api/v1/esmc/encode:
    post:
      summary: Encode Protein Sequence With ESM C
      description: >
        Tokenize an `ESMProtein` (sequence track only) into an
        `ESMProteinTensor` ready for logits / embedding retrieval. ESM C
        operates over the sequence track exclusively.
      operationId: esmcEncode
      tags:
        - Embeddings
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ESMCEncodeRequest'
            examples:
              SimpleEncode:
                $ref: '#/components/examples/SimpleEncodeExample'
      responses:
        '200':
          description: Sequence tensor for the supplied protein.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ESMProteinTensor'
        '4XX':
          $ref: '#/components/responses/ErrorResponse'
  /api/v1/esmc/logits:
    post:
      summary: Get ESM C Logits And Embeddings
      description: >
        Returns per-residue sequence logits and (optionally) embeddings or
        hidden states for an `ESMProteinTensor` produced by `esmc/encode`.
        Use for representation learning, classification heads, mutational
        effect prediction, and similar downstream tasks.
      operationId: esmcLogits
      tags:
        - Sampling
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ESMCLogitsRequest'
      responses:
        '200':
          description: Logits and embedding output.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LogitsOutput'
        '4XX':
          $ref: '#/components/responses/ErrorResponse'
components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      description: Forge API token issued via forge.evolutionaryscale.ai.
  schemas:
    ESMProtein:
      type: object
      properties:
        sequence:
          type: string
          description: Amino acid sequence using one-letter codes.
          example: "MKTAYIAKQRQISFVKAHFSRQLEERLGLIEVQ"
    ESMProteinTensor:
      type: object
      properties:
        sequence:
          type: array
          items:
            type: integer
    LogitsConfig:
      type: object
      properties:
        sequence:
          type: boolean
          default: true
        return_embeddings:
          type: boolean
          default: false
        return_hidden_states:
          type: boolean
          default: false
        ith_hidden_layer:
          type: integer
          default: -1
    LogitsOutput:
      type: object
      properties:
        logits:
          type: object
          properties:
            sequence:
              type: array
              items:
                type: array
                items:
                  type: number
        embeddings:
          type: array
          items:
            type: array
            items:
              type: number
        hidden_states:
          type: array
          items:
            type: array
            items:
              type: array
              items:
                type: number
    ESMCEncodeRequest:
      type: object
      required:
        - model
        - protein
      properties:
        model:
          type: string
          example: esmc-300m-2024-12
          enum:
            - esmc-300m-2024-12
            - esmc-600m-2024-12
            - esmc-6b-2024-12
        protein:
          $ref: '#/components/schemas/ESMProtein'
    ESMCLogitsRequest:
      type: object
      required:
        - model
        - protein_tensor
      properties:
        model:
          type: string
          example: esmc-300m-2024-12
        protein_tensor:
          $ref: '#/components/schemas/ESMProteinTensor'
        config:
          $ref: '#/components/schemas/LogitsConfig'
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            type:
              type: string
            message:
              type: string
            code:
              type: string
  responses:
    ErrorResponse:
      description: Error returned by the Forge API.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  examples:
    SimpleEncodeExample:
      summary: Encode a short protein sequence
      value:
        model: esmc-300m-2024-12
        protein:
          sequence: "AAAAA"