> ## Documentation Index > Fetch the complete documentation index at: https://docs.replicas.dev/llms.txt > Use this file to discover all available pages before exploring further. # Fork chat > Starts a new chat that continues from this chat's history, optionally on another coding agent and with a first message. The replica must be active. ## OpenAPI ````yaml /openapi.json post /v1/replica/{id}/chats/{chat_id}/fork openapi: 3.1.0 info: title: Replicas API version: 2.0.0 description: >- Create and control workspaces, and manage the environments, automations, and learnings they run with. servers: - url: https://api.replicas.dev description: Production API security: - apiKey: [] tags: - name: Replica description: >- A replica is a Replicas workspace: a cloud sandbox where a coding agent works on your repositories. - name: Chats description: Manage the agent chats inside a replica. - name: Message queue description: Messages waiting for the agent to finish its turn. - name: Commands and terminals description: Run commands and open shells in a replica. - name: Pull requests description: Inspect and act on pull requests a replica opened. - name: Previews description: Public URLs for ports in a replica. - name: Canvas description: Plans, reports, and other files agents produce. - name: Sharing description: Add replicas to members' Shared view. - name: Environments description: >- Environments define what a workspace starts with. The `global` environment applies to every workspace. - name: Environment variables description: Variables injected into workspaces. - name: Environment files description: Files written into workspaces. - name: Environment skills description: Agent skills installed into workspaces. - name: Environment MCPs description: MCP servers available to workspace agents. - name: Hooks description: Scripts that run when warm pool snapshots build and when workspaces start. - name: Warm pools description: Pre-built workspaces that start faster. - name: Automations description: Run agents on schedules and events. - name: Repositories description: Repositories and repository sets connected to the organization. - name: Learnings description: Organization skills every workspace agent loads. - name: Agent credentials description: >- API keys and endpoints that coding agents use. Connect Claude, Codex, and Muse subscriptions with the CLI. - name: Plugins description: Connect integrations that workspace agents can use. - name: Organization description: Who you are and who is in your organization. - name: Media description: Screenshots, recordings, and other files workspaces produce. - name: Slack description: Route Slack threads to workspaces. - name: Workspace identity description: OIDC keys for verifying workspace identity tokens. paths: /v1/replica/{id}/chats/{chat_id}/fork: post: tags: - Chats summary: Fork chat description: >- Starts a new chat that continues from this chat's history, optionally on another coding agent and with a first message. The replica must be active. operationId: forkReplicaChat parameters: - name: id in: path required: true description: Replica ID schema: type: string format: uuid - name: chat_id in: path required: true description: Chat ID schema: type: string - $ref: '#/components/parameters/ApiVersion' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ForkChatRequest' responses: '201': description: Created content: application/json: schema: $ref: '#/components/schemas/ForkWorkspaceChatResponse' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '404': $ref: '#/components/responses/NotFound' '409': $ref: '#/components/responses/Conflict' '500': $ref: '#/components/responses/InternalServerError' components: parameters: ApiVersion: name: X-Replicas-Api-Version in: header description: >- API version. `2026-10-07` returns `snake_case` responses. See [versioning](/features/api#versioning). required: false schema: type: string enum: - '2026-10-07' schemas: ForkChatRequest: type: object description: >- Request body for continuing an existing chat on another coding agent harness properties: provider: type: string enum: - claude - codex - cursor - opencode - pi description: >- Harness to continue the chat on. It must have credentials connected in the workspace. model: type: string description: Model for the forked chat. Defaults to the harness default. thinking_level: type: string enum: - low - medium - high - xhigh - max - ultra - ultracode description: Reasoning effort for the forked chat title: type: string description: >- Title for the forked chat. Defaults to a title derived from the source chat. message: type: string description: >- Optional first instruction for the new harness, sent alongside the inherited context. Empty or whitespace-only values preserve the default continuation behavior. id: type: string format: uuid description: Optional client-generated chat ID. client_request_id: type: string description: Opaque client-chosen id echoed back in the `chat.created` event enable_interactive_tools: type: boolean description: Allow the forked chat's first turn to use interactive tools required: - provider ForkWorkspaceChatResponse: type: object properties: chat: $ref: '#/components/schemas/WorkspaceChat' required: - chat WorkspaceChat: type: object properties: id: type: string format: uuid provider: type: string enum: - claude - codex - cursor - muse - opencode - pi model: type: string description: Selected model retained for future messages in this chat. title: type: string created_at: type: string format: date-time updated_at: type: string format: date-time processing: type: boolean parent_chat_id: type: - string - 'null' format: uuid last_message_text: type: - string - 'null' fork: description: >- Fork lineage and progress, when this chat was forked from another chat in the workspace oneOf: - $ref: '#/components/schemas/ChatFork' - type: 'null' required: - id - provider - title - created_at - updated_at - processing - parent_chat_id Error: type: object properties: error: type: string description: Error message details: type: - string - 'null' description: Additional error details code: type: string description: Machine-readable error code when available required: - error ChatFork: type: object description: Set on a chat that was forked from another chat in the same workspace properties: source: type: object description: The chat this one was forked from properties: chat_id: type: string format: uuid provider: type: string enum: - claude - codex - cursor - opencode - pi title: type: string required: - chat_id - provider - title trigger: type: string enum: - manual - auto description: >- `manual` for a requested fork, `auto` when the source harness hit its usage limit and the owner opted into automatic fallback reason: type: string enum: - rate_limit - out_of_credits description: Why an automatic fork happened state: type: string enum: - preparing - ready - failed description: >- `preparing` while the transcript handoff is assembled; `processing` stays true until it leaves this state error: type: string description: Failure reason when `state` is `failed` started_at: type: string format: date-time completed_at: type: string format: date-time required: - source - trigger - state - started_at responses: BadRequest: description: Bad request - Missing or invalid parameters content: application/json: schema: $ref: '#/components/schemas/Error' Unauthorized: description: Unauthorized - Invalid or missing API key content: application/json: schema: $ref: '#/components/schemas/Error' NotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/Error' Conflict: description: >- Conflict - Resource already exists or operation conflicts with current state content: application/json: schema: $ref: '#/components/schemas/Error' InternalServerError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: apiKey: type: http scheme: bearer description: Organization or personal API key from **Settings → API Keys**. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.