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

> ## Agent Instructions
> To build and serve your own model, start at /deploy/development/quickstart and /deploy/development/overview. Deploying is the default path: reactor init scaffolds a workspace, reactor auth login authenticates, and reactor model deploy registers the model, publishes the release with the weights/ folder, and activates it on Reactor's GPUs, in one command from that workspace. Docker must be running, because the publish step builds the image locally. Bump model.version in reactor.yaml before redeploying a change, because a release that already has an image is reactivated as it is. Deployment access is granted per account, so contact team@reactor.inc if a deploy is refused. Every key in reactor.yaml is documented at /deploy/platform/reactor-yaml. Model code imports reactor_runtime; Python client code imports reactor_sdk. The runtime overview explains the model interface. Running the model on your own machine with reactor run is optional and needs a GPU you attach with --gpus; /deploy/development/local-testing covers that loop and pairs a complete brightness model with a Python client test in a separate brightness-test workspace.
> Reactor hosts multiple models, each with its own connect slug (modelName) and command/event schema. The video model catalog — slug, typed SDK package, and links to its schema — is at /model-api-reference/overview. Robotics policy documentation starts at /robotics/overview; The launch policies are Cosmos Nano DROID (/robotics/cosmos/nano-policy-droid/), DreamZero DROID (/robotics/dreamzero/droid/), and FLUX Action DROID (/robotics/flux-action/droid/), organized by model family and embodiment. Some models expose one slug per experience (e.g. HappyOyster); always take the slug from the model's own pages, never guess it.
> Fastest path to a working app: `npx create-reactor-app my-app --model=<slug>` scaffolds a complete app with secure auth wired up. Typed TypeScript SDKs are published as @reactor-models/<model>; Python uses the base reactor-sdk package.
> Auth: exchange an API key (rk_...) for a JWT via POST https://api.reactor.inc/tokens from your server. Never put the API key in client-side code.
> Append .md to any docs URL for clean Markdown. Search these docs via the MCP server at https://docs.reactor.inc/mcp.

# Start a multipart upload

> Starts a multipart upload of one weight file, for files too large for a single `PUT`
(over 5 GiB) and up to 5 TiB. The response splits the file into parts of `part_size`
bytes (64 MiB by default) and returns a presigned URL for each. `PUT` each part's bytes
to its `url`, keep the `ETag` response header of each part, then call
`POST .../weights/multipart/complete`.

With `sha256` set (and `force` unset), an identical file from an earlier release returns
`copied: true` with no parts: skip the upload.

Callable by an `account_admin` or `developer` of the owning account when model serving is
enabled for the account.




## OpenAPI

````yaml /openapi.yaml post /models/{id}/releases/{release}/weights/multipart
openapi: 3.1.0
info:
  title: Reactor Platform API
  version: '1'
  description: >
    The Reactor Platform API mints session tokens, starts and operates sessions,
    negotiates media

    transport, and manages your account, models, and deployments. Every path is
    relative to

    `https://api.reactor.inc`. See the
    [Introduction](/platform-api/introduction) and

    [Authentication](/platform-api/authentication) pages for credentials,
    versioning, and errors.
  contact:
    name: Reactor support
    url: https://docs.reactor.inc/resources/support
servers:
  - url: https://api.reactor.inc
    description: Production
security:
  - apiKey: []
tags:
  - name: Status
    description: >-
      Public, unauthenticated endpoints for service health, pricing, and the
      values the API accepts.
  - name: Tokens
    description: >
      Exchange a long-lived API key for a short-lived, session-scoped token that
      a client can use

      to create and operate sessions without holding the key.
  - name: Users
    description: >
      Read your own user record, your account's roster, and account memberships,
      and manage

      member roles as an account admin.
  - name: API Keys
    description: >-
      Revoke API keys. Use the [Dashboard](https://reactor.inc/dashboard) to
      list or create keys. The CLI can also create a key with `reactor auth
      login`.
  - name: Sessions
    description: >
      Create, inspect, and end sessions. A session holds one running model for
      one client

      application; media and messages flow over a transport you attach to it
      afterwards.
  - name: Transport
    description: >
      Attach a client to a session. WebRTC signaling carries ICE servers, SDP,
      and ICE candidates;

      a LiveKit room connection lets the session join a room you host.
  - name: Files
    description: >
      Upload files a model reads, either for one running session or ahead of
      time for sessions you

      have not started yet.
  - name: Recordings
    description: >
      Fetch the recorded video of a session as an HLS playlist, during the
      session or after it ends.
  - name: Accounts
    description: >
      Read and manage the account your credential acts in: its name and slug,
      its credit

      balance, its effective quotas, and its accelerator capacity.
  - name: Invitations
    description: >
      Invite people to your account by email, and manage pending invitations.
      The recipient

      accepts from the emailed link while signed in to the dashboard.
  - name: Usage
    description: >
      List the sessions your account has run, filter them by status, date,
      model, or API key,

      and read exact session totals for a date window.
  - name: Models
    description: >
      Register, read, update, and delete the models your account serves, and
      list the models you can

      use. The `reactor model` CLI commands are built on these endpoints.
  - name: Releases
    description: >
      Register a model's versioned releases, push their container image, and
      deploy a release with a

      per-region instance plan.
  - name: Model Weights
    description: >
      Upload and inspect the weights bundle of a release: single-request
      uploads, multipart uploads

      for large files, and the server-side finalize that marks a bundle
      complete.
  - name: Model Schemas
    description: >
      Attach an OpenAPI schema to a release that describes the model's commands,
      messages, and

      tracks. Schemas of public models are readable without credentials.
  - name: Model Access
    description: |
      Share a private model with other accounts, one environment at a time.
  - name: Projects
    description: >
      A project is the deploy identity of a model you serve on Reactor. Each
      model is one

      project, with its own UUID. Creating a project also creates its
      `production` environment.
  - name: Environments
    description: >
      An environment is a named deploy target of a project, such as `production`
      or `staging`.

      Each write to an environment creates its next revision, and the newest
      revision is what the

      environment runs. Environment access grants let another account start
      sessions on one

      environment.
  - name: Revisions
    description: >
      A revision is an immutable, numbered snapshot of one environment: its
      model image, weights,

      resources, instances, and variables. An environment's revisions, newest
      first, are its change

      log.
  - name: Images
    description: >
      Model images are the container images pushed to your model's repository,
      named by digest.

      Experimental: this API can change without notice.
  - name: Weight Sets
    description: >
      A weight set is a version-2 weights bundle, named by its set digest. Push
      the files, then put

      the manifest. Available when weight sets are enabled for your account.
      Experimental: this API

      can change without notice.
  - name: Tags
    description: >
      A tag is a movable name on one model image or one weight set of a project.
      A release of the

      model is a read-only tag. Experimental: this API can change without
      notice.
paths:
  /models/{id}/releases/{release}/weights/multipart:
    parameters:
      - $ref: '#/components/parameters/ModelId'
      - $ref: '#/components/parameters/ModelRelease'
    post:
      tags:
        - Model Weights
      summary: Start a multipart upload
      description: >
        Starts a multipart upload of one weight file, for files too large for a
        single `PUT`

        (over 5 GiB) and up to 5 TiB. The response splits the file into parts of
        `part_size`

        bytes (64 MiB by default) and returns a presigned URL for each. `PUT`
        each part's bytes

        to its `url`, keep the `ETag` response header of each part, then call

        `POST .../weights/multipart/complete`.


        With `sha256` set (and `force` unset), an identical file from an earlier
        release returns

        `copied: true` with no parts: skip the upload.


        Callable by an `account_admin` or `developer` of the owning account when
        model serving is

        enabled for the account.
      operationId: createModelWeightsMultipart
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ModelMultipartInitRequest'
            example:
              name: model.safetensors
              size: 21474836480
              sha256: 9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08
      responses:
        '201':
          description: The upload was started, or an identical file was found.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ModelMultipartInitResponse'
              example:
                upload_id: 2~xYzAbC123
                key: >-
                  partners/8c8b7e12-a4c1-4627-b0a0-5d2e9f3a7b61/weights/your-model/7b3f1bc2-a4e5-4d78-b9c1-0e6c2f9a1d34/v1.2.3-gabcdef0/files/model.safetensors
                part_size: 67108864
                parts:
                  - part_number: 1
                    url: >-
                      https://storage.example.com/...?partNumber=1&uploadId=2~xYzAbC123
                    content_length: 67108864
                  - part_number: 2
                    url: >-
                      https://storage.example.com/...?partNumber=2&uploadId=2~xYzAbC123
                    content_length: 67108864
        '400':
          description: >-
            `name` is missing or unsafe, or `size` is not between 1 byte and 5
            TiB.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          description: >-
            You do not own the model (returned whether or not it exists), or
            model serving is not enabled for your account.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: The release is not registered for this model.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '503':
          $ref: '#/components/responses/ServiceUnavailable'
components:
  parameters:
    ModelId:
      name: id
      in: path
      required: true
      description: >-
        The model's ID (not its project ID). Find it with `GET
        /models?name=your-org/your-model`.
      schema:
        type: string
        format: uuid
    ModelRelease:
      name: release
      in: path
      required: true
      description: The release tag, such as `v1.2.3-gabcdef0`.
      schema:
        type: string
        example: v1.2.3-gabcdef0
  schemas:
    ModelMultipartInitRequest:
      type: object
      required:
        - name
        - size
      properties:
        name:
          type: string
          example: model.safetensors
        size:
          type: integer
          format: int64
          minimum: 1
          maximum: 5497558138880
        sha256:
          type: string
          description: >-
            Hex SHA-256 of the file, to look for an identical file in earlier
            releases.
        force:
          type: boolean
          default: false
          description: Skip the identical-file lookup.
    ModelMultipartInitResponse:
      type: object
      required:
        - key
      properties:
        upload_id:
          type: string
        key:
          type: string
          description: The file's storage key.
        part_size:
          type: integer
          format: int64
        parts:
          type: array
          items:
            $ref: '#/components/schemas/ModelMultipartPartUrl'
        copied:
          type: boolean
          description: '`true` when an identical file was found; skip the upload.'
        source_path:
          type: string
    Error:
      type: object
      required:
        - error
      properties:
        error:
          type: string
          description: >-
            A stable error code (for example `not_found`) on newer routes, or a
            sentence on older ones. When `message` is present, branch on
            `error`.
        message:
          type: string
          description: >-
            A human-readable explanation. Do not parse it; its wording may
            change.
        resource:
          type: string
          description: The type of the resource a `not_found` refers to.
        reason:
          type: string
          description: >-
            A more specific cause for `failed_precondition`, `aborted`, and some
            `invalid_request` errors.
    ModelMultipartPartUrl:
      type: object
      required:
        - part_number
        - url
        - content_length
      properties:
        part_number:
          type: integer
          minimum: 1
          maximum: 10000
        url:
          type: string
          format: uri
          description: '`PUT` the part''s bytes here.'
        content_length:
          type: integer
          format: int64
          description: The exact byte length of this part.
  responses:
    Unauthorized:
      description: The credential is missing, invalid, or expired.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    ServiceUnavailable:
      description: A dependency is temporarily unavailable. Retry with backoff.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    apiKey:
      type: http
      scheme: bearer
      description: >-
        A Reactor API key (`rk_...`), sent as `Authorization: Bearer rk_...`.
        Keep it on a server.

````

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