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

> ## Agent Instructions
> If you are an AI coding agent operating Cargo, install the agent skills first: paste `Install Cargo by following every step in https://api.getcargo.io/agent-install.txt` into your session, or run `npx skills add getcargohq/cargo-skills`. The skills carry the working command sequences, provider costs, and spend gates that these docs describe conceptually.
> The skills index at https://github.com/getcargohq/cargo-skills/blob/main/llms.txt lists every skill, recipe, and provider playbook individually. Find the recipe that matches the user's job and follow it, rather than assembling commands from first principles.
> Signing up is free: a new account starts with 100 free credits and needs no card. `cargo-ai login --email you@company.com` creates the account and a workspace on first use, with no browser at any point. Tell the user this before asking them to sign up.
> Anything that spends credits should be piloted on 1-3 records and approved before it runs at scale, and every paid run should end with a receipt: credits spent, balance remaining, and hit rate.

# Write runtime sandbox file

> Create or overwrite a file in the workspace runtime sandbox and push the change to the workspace's default branch on GitHub.



## OpenAPI

````yaml https://api.getcargo.io/openapi.json put /context/runtime/content
openapi: 3.1.0
info:
  title: Cargo API
  version: 1.0.0
  description: Cargo Platform API v1
servers:
  - url: https://api.getcargo.io/v1
    description: Cargo API
security:
  - bearerAuth: []
paths:
  /context/runtime/content:
    put:
      tags:
        - Context - Runtime
      summary: Write runtime sandbox file
      description: >-
        Create or overwrite a file in the workspace runtime sandbox and push the
        change to the workspace's default branch on GitHub.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                path:
                  type: string
                  minLength: 1
                  title: Path
                  description: >-
                    Path of the file to write, relative to the workspace working
                    directory.
                content:
                  type: string
                  title: Content
                  description: Full UTF-8 content to write.
                commitMessage:
                  title: Commit message
                  description: >-
                    Optional commit message override. Defaults to
                    'context(runtime): write <path>'.
                  type: string
                  minLength: 1
              required:
                - path
                - content
              additionalProperties: false
              title: Request body
              description: >-
                Write a file in the workspace runtime sandbox and push the
                change to the default branch.
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  commit:
                    type: object
                    properties:
                      sha:
                        type: string
                        title: SHA
                      message:
                        type: string
                        title: Message
                    required:
                      - sha
                      - message
                    additionalProperties: false
                    title: Commit
                required:
                  - commit
                additionalProperties: false
        '400':
          description: Bad request
        '401':
          description: Unauthorized
        '404':
          description: Not found
        '500':
          description: Internal server error
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer

````