> ## 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 weights upload

> Starts a multipart upload for one large file of the weight set, and returns one presigned
`PUT` URL per part. Upload each part, keep each response's `ETag`, then complete the upload.
A file already stored at its size returns `copied: true` and needs no upload.

Files can be up to 5 TiB. Available when weight sets are enabled for your account. Requires
the `account_admin` or `developer` role and Serve access.




## OpenAPI

````yaml /openapi.yaml post /projects/{proj_id}/weights/{set}/uploads/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:
  /projects/{proj_id}/weights/{set}/uploads/multipart:
    parameters:
      - $ref: '#/components/parameters/ProjectProjId'
      - $ref: '#/components/parameters/ProjectFullSetDigest'
    post:
      tags:
        - Weight Sets
      summary: Start a multipart weights upload
      description: >
        Starts a multipart upload for one large file of the weight set, and
        returns one presigned

        `PUT` URL per part. Upload each part, keep each response's `ETag`, then
        complete the upload.

        A file already stored at its size returns `copied: true` and needs no
        upload.


        Files can be up to 5 TiB. Available when weight sets are enabled for
        your account. Requires

        the `account_admin` or `developer` role and Serve access.
      operationId: createWeightsMultipartUpload
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ProjectMultipartInitRequest'
            example:
              name: model.safetensors
              size: 12884901888
              sha256: 2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae
      responses:
        '201':
          description: The upload was started, or the file is already stored.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProjectMultipartInitResponse'
              example:
                upload_id: 2~nC3yQeXbVZ8a
                key: >-
                  partners/7d2e4f6a-1b3c-4d5e-8f9a-0b1c2d3e4f5a/blobs/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae
                part_size: 536870912
                parts:
                  - part_number: 1
                    url: https://storage.example.com/part?n=1&signature=...
                    content_length: 536870912
                  - part_number: 2
                    url: https://storage.example.com/part?n=2&signature=...
                    content_length: 536870912
        '400':
          description: >-
            The body is malformed, `name` or `sha256` is missing, 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: No write access to the project, or Serve access is not enabled.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '409':
          description: '`failed_precondition` with `reason` `set_objects_off`.'
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '503':
          $ref: '#/components/responses/ServiceUnavailable'
components:
  parameters:
    ProjectProjId:
      name: proj_id
      in: path
      required: true
      description: The project's ID, a UUID. It is not the model's ID.
      schema:
        type: string
        format: uuid
    ProjectFullSetDigest:
      name: set
      in: path
      required: true
      description: >-
        The full set digest, `sha256:<64 hex>` or the 64 hex characters. A tag
        or prefix is not accepted.
      schema:
        type: string
  schemas:
    ProjectMultipartInitRequest:
      type: object
      required:
        - name
        - size
        - sha256
      properties:
        name:
          type: string
          description: The file's path in the manifest.
        size:
          type: integer
          format: int64
          minimum: 1
          description: Bytes, up to 5 TiB.
        sha256:
          type: string
          description: The file's SHA-256, as 64 hex characters.
        force:
          type: boolean
          default: false
    ProjectMultipartInitResponse:
      type: object
      required:
        - key
      properties:
        upload_id:
          type: string
        key:
          type: string
        part_size:
          type: integer
          format: int64
        parts:
          type: array
          items:
            $ref: '#/components/schemas/ProjectMultipartPartUrl'
        copied:
          type: boolean
          description: True when the file is already stored. Upload nothing.
        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.
    ProjectMultipartPartUrl:
      type: object
      properties:
        part_number:
          type: integer
        url:
          type: string
          description: Upload the part here with HTTP `PUT`.
        content_length:
          type: integer
          format: int64
          description: The part's size in bytes. Omitted on refresh.
  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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