> ## Documentation Index > Fetch the complete documentation index at: https://docs.checkfu.com/llms.txt > Use this file to discover all available pages before exploring further. # Spawn a child Session > Creates one child Session with its first thread from the parent Session's drive plane, selecting the child's Agent and Environment and seeding its opening content. Returns the child Session and thread identities; the parent keeps running and the child admits under the same live authority as any Session create. Checkfu support posture: alpha; hosted. Required evidence journey: session-turn. Deployment-specific readiness and the latest proven release are available from GET /v1/support/capabilities. ## OpenAPI ````yaml /openapi.json post /v1/sessions/{id}/children openapi: 3.1.0 info: title: Checkfu API version: '2026-08-31' description: >- Authentication is declared per operation: API-key, runtime, or connector bearer; Automation signature; or credential-free pairing redemption. Every general Checkfu REST request requires the dated `Checkfu-Version` header (one of: 2026-08-31); the three MCP JSON-RPC transports use `MCP-Protocol-Version`, A2A uses `A2A-Version`, and the provider OAuth callback carries neither Checkfu header. API keys resolve one Workspace without a request selector; authenticated responses identify it with `Checkfu-Workspace-Id`. servers: - url: https://api.checkfu.com security: - bearerAuth: [] tags: - name: organizations - name: sourceRepositories - name: tenants - name: workspaces - name: principals - name: principalGroups - name: principalAccessCredentials - name: apiKeys - name: agents - name: harnesses - name: harnessRuntime - name: computerProfiles - name: permissionAssignments - name: actionPolicies - name: files - name: memoryStores - name: dreams - name: modelCredentials - name: modelRoutingProfiles - name: blueprintInstallations - name: toolSources - name: skills - name: skillSources - name: agentSources - name: agentBlueprints - name: skillProposals - name: instructionProposals - name: catalog - name: concepts - name: support - name: bootstrapRequests - name: connections - name: connectionVaults - name: connectionAssignments - name: connectedRuntimes - name: fileTrees - name: collaboration - name: automationGraphs - name: automations - name: actionApprovals - name: standingApprovals - name: usage - name: models - name: outcomes - name: budgets - name: billing - name: sessions - name: audit - name: sessionExports - name: runs - name: runnerPools - name: transcripts - name: sessionWatches - name: sessionHandoffs - name: sessionCapsules - name: sessionTrajectories - name: webhookEndpoints - name: integrationGateway - name: workEnvironments - name: computers - name: computerScreens - name: computerBrowserObservations - name: computerBrowserActions - name: environments - name: vaults - name: apiMcp - name: a2a paths: /v1/sessions/{id}/children: post: tags: - sessions summary: Spawn a child Session description: >- Creates one child Session with its first thread from the parent Session's drive plane, selecting the child's Agent and Environment and seeding its opening content. Returns the child Session and thread identities; the parent keeps running and the child admits under the same live authority as any Session create. Checkfu support posture: alpha; hosted. Required evidence journey: session-turn. Deployment-specific readiness and the latest proven release are available from GET /v1/support/capabilities. operationId: sessions.spawnChild parameters: - name: id in: path schema: $ref: '#/components/schemas/SessionId' required: true - name: checkfu-version in: header schema: type: string enum: - '2026-08-31' required: true - name: idempotency-key in: header schema: type: string allOf: - maxLength: 255 - minLength: 1 required: true requestBody: content: application/json: schema: type: object properties: agent: $ref: '#/components/schemas/ManagedAgentsSessionAgentParams' environment_id: $ref: '#/components/schemas/EnvironmentId' content: type: string title: anyOf: - type: string - type: 'null' required: - agent - environment_id - content additionalProperties: false required: true responses: '201': description: Success content: application/json: schema: type: object properties: child_session_id: $ref: '#/components/schemas/SessionId' child_thread_id: type: string required: - child_session_id - child_thread_id additionalProperties: false headers: checkfu-workspace-id: description: The Workspace resolved from the authenticated bearer credential. required: true schema: $ref: '#/components/schemas/WorkspaceId' '400': description: Typed Checkfu wire error content: application/json: schema: $ref: '#/components/schemas/ValidationMalformedError' '401': description: Typed Checkfu wire error content: application/json: schema: type: object required: - error properties: error: type: object required: - type - message - more properties: type: type: string enum: - auth.invalid_key message: type: string more: type: string enum: - >- https://docs.checkfu.com/reference/errors#auth-invalid-key description: >- Stable public documentation and remedy for this error type. additionalProperties: false additionalProperties: false '403': description: >- The organization, tenant, or workspace backing this key is administratively disabled. | Deployment governance or retention policy denied the request. content: application/json: schema: anyOf: - type: object required: - error properties: error: type: object properties: type: type: string enum: - auth.disabled_tenancy message: type: string more: type: string enum: - >- https://docs.checkfu.com/reference/errors#auth-disabled-tenancy description: >- Stable public documentation and remedy for this error type. required: - type - message - more additionalProperties: false additionalProperties: false - $ref: '#/components/schemas/PolicyDeniedError' '404': description: >- The requested resource does not exist in the resolved deployment boundary. content: application/json: schema: $ref: '#/components/schemas/ValidationNotFoundError' '409': description: The request conflicts with the resource's current state. content: application/json: schema: $ref: '#/components/schemas/ValidationConflictError' '429': description: Typed Checkfu wire error headers: retry-after: description: >- Delay in seconds for rate limits or deployment quotas with a known release or UTC reset boundary required: false schema: type: integer minimum: 1 content: application/json: schema: type: object required: - error properties: error: type: object required: - type - message - more properties: type: type: string enum: - budget.exceeded message: type: string more: type: string enum: - >- https://docs.checkfu.com/reference/errors#budget-exceeded description: >- Stable public documentation and remedy for this error type. additionalProperties: false additionalProperties: false '500': description: >- An unexpected internal failure occurred; the message contains an opaque incident reference. content: application/json: schema: $ref: '#/components/schemas/RuntimeInternalError' security: - bearerAuth: [] components: schemas: SessionId: type: string allOf: - pattern: ^sess_[0-9a-f]{32}$ ManagedAgentsSessionAgentParams: anyOf: - $ref: '#/components/schemas/AgentId' - $ref: '#/components/schemas/ManagedAgentsAgentParams' - $ref: '#/components/schemas/ManagedAgentsAgentWithOverridesParams' EnvironmentId: type: string allOf: - pattern: ^env_[0-9a-f]{32}$ WorkspaceId: type: string allOf: - pattern: ^wrkspc_[0-9a-f]{32}$ ValidationMalformedError: type: object properties: error: type: object properties: type: type: string enum: - validation.malformed message: type: string more: type: string enum: - https://docs.checkfu.com/reference/errors#validation-malformed description: Stable public documentation and remedy for this error type. required: - type - message - more additionalProperties: false required: - error additionalProperties: false description: >- The request could not be decoded or violated a declared input constraint. PolicyDeniedError: type: object properties: error: type: object properties: type: type: string enum: - policy.denied message: type: string more: type: string enum: - https://docs.checkfu.com/reference/errors#policy-denied description: Stable public documentation and remedy for this error type. required: - type - message - more additionalProperties: false required: - error additionalProperties: false description: Deployment governance or retention policy denied the request. ValidationNotFoundError: type: object properties: error: type: object properties: type: type: string enum: - validation.not_found message: type: string more: type: string enum: - https://docs.checkfu.com/reference/errors#validation-not-found description: Stable public documentation and remedy for this error type. required: - type - message - more additionalProperties: false required: - error additionalProperties: false description: >- The requested resource does not exist in the resolved deployment boundary. ValidationConflictError: type: object properties: error: type: object properties: type: type: string enum: - validation.conflict message: type: string more: type: string enum: - https://docs.checkfu.com/reference/errors#validation-conflict description: Stable public documentation and remedy for this error type. required: - type - message - more additionalProperties: false required: - error additionalProperties: false description: The request conflicts with the resource's current state. RuntimeInternalError: type: object properties: error: type: object properties: type: type: string enum: - runtime.internal message: type: string more: type: string enum: - https://docs.checkfu.com/reference/errors#runtime-internal description: Stable public documentation and remedy for this error type. required: - type - message - more additionalProperties: false required: - error additionalProperties: false description: >- An unexpected internal failure occurred; the message contains an opaque incident reference. AgentId: type: string allOf: - pattern: ^agent_[0-9a-f]{32}$ ManagedAgentsAgentParams: type: object properties: type: type: string enum: - agent id: $ref: '#/components/schemas/AgentId' version: type: integer allOf: - exclusiveMinimum: 0 required: - type - id additionalProperties: false ManagedAgentsAgentWithOverridesParams: type: object properties: type: type: string enum: - agent_with_overrides id: $ref: '#/components/schemas/AgentId' version: type: integer allOf: - exclusiveMinimum: 0 harness: $ref: '#/components/schemas/ManagedAgentsHarnessReference' mcp_servers: $ref: '#/components/schemas/Arrays_2' model: $ref: '#/components/schemas/ManagedAgentsModelConfigParams' skills: type: array items: $ref: '#/components/schemas/Union_28' system: anyOf: - $ref: '#/components/schemas/ManagedAgentsSessionSystem' - type: 'null' tools: $ref: '#/components/schemas/Arrays_3' required: - type - id additionalProperties: false ManagedAgentsHarnessReference: type: string allOf: - pattern: ^[a-z0-9](?:[a-z0-9._-]{0,93})(?:@(?:latest|[1-9][0-9]{0,8}))?$ description: >- a harness catalog name this deployment serves: checkfu, claude-code, codex, cursor, hermes, openclaw, openclaw-connected, opencode, pi Arrays_2: type: array items: $ref: '#/components/schemas/Objects_12' allOf: - maxItems: 20 ManagedAgentsModelConfigParams: anyOf: - type: string - type: object properties: id: type: string effort: anyOf: - anyOf: - $ref: '#/components/schemas/Union_23' - $ref: '#/components/schemas/Union_24' - type: 'null' inference_geo: anyOf: - $ref: '#/components/schemas/Union_11' - type: 'null' speed: anyOf: - type: string enum: - standard - fast - type: 'null' required: - id additionalProperties: false Union_28: anyOf: - type: object properties: type: type: string enum: - anthropic skill_id: type: string version: anyOf: - type: string - type: 'null' required: - type - skill_id additionalProperties: false - type: object properties: type: type: string enum: - custom skill_id: type: string version: anyOf: - type: string - type: 'null' required: - type - skill_id additionalProperties: false ManagedAgentsSessionSystem: type: string Arrays_3: type: array items: $ref: '#/components/schemas/ManagedAgentsToolParams' allOf: - maxItems: 128 Objects_12: type: object properties: type: type: string enum: - url name: type: string allOf: - minLength: 1 - maxLength: 255 url: type: string allOf: - minLength: 1 - maxLength: 2048 required: - type - name - url additionalProperties: false Union_23: type: string enum: - low - medium - high - xhigh - max Union_24: anyOf: - type: object properties: type: type: string enum: - low required: - type additionalProperties: false - type: object properties: type: type: string enum: - medium required: - type additionalProperties: false - type: object properties: type: type: string enum: - high required: - type additionalProperties: false - type: object properties: type: type: string enum: - xhigh required: - type additionalProperties: false - type: object properties: type: type: string enum: - max required: - type additionalProperties: false Union_11: type: string enum: - global - us ManagedAgentsToolParams: anyOf: - type: object properties: type: type: string enum: - agent_toolset_20260401 configs: type: array items: $ref: '#/components/schemas/ManagedAgentsAgentToolConfigParams' default_config: anyOf: - $ref: '#/components/schemas/Objects_16' - type: 'null' required: - type additionalProperties: false - type: object properties: type: type: string enum: - mcp_toolset mcp_server_name: type: string allOf: - minLength: 1 - maxLength: 255 configs: type: array items: type: object properties: name: type: string allOf: - minLength: 1 - maxLength: 128 enabled: type: boolean permission_policy: $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' required: - name additionalProperties: false default_config: anyOf: - $ref: '#/components/schemas/Objects_16' - type: 'null' required: - type - mcp_server_name additionalProperties: false - $ref: '#/components/schemas/Objects_17' ManagedAgentsAgentToolConfigParams: anyOf: - type: object properties: name: type: string enum: - bash type: type: string enum: - bash enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - edit type: type: string enum: - edit enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - glob type: type: string enum: - glob enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - grep type: type: string enum: - grep enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - read type: type: string enum: - read enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - web_fetch type: type: string enum: - web_fetch enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' allowed_domains: $ref: '#/components/schemas/Arrays_4' blocked_domains: $ref: '#/components/schemas/Arrays_4' max_content_tokens: anyOf: - type: integer allOf: - exclusiveMinimum: 0 - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - web_search type: type: string enum: - web_search enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' allowed_domains: $ref: '#/components/schemas/Arrays_4' blocked_domains: $ref: '#/components/schemas/Arrays_4' user_location: anyOf: - $ref: '#/components/schemas/Objects_15' - type: 'null' required: - name additionalProperties: false - type: object properties: name: type: string enum: - write type: type: string enum: - write enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' required: - name additionalProperties: false Objects_16: type: object properties: enabled: anyOf: - type: boolean - type: 'null' permission_policy: anyOf: - $ref: '#/components/schemas/ManagedAgentsPermissionPolicy' - type: 'null' additionalProperties: false ManagedAgentsPermissionPolicy: anyOf: - type: object properties: type: type: string enum: - always_allow required: - type additionalProperties: false - type: object properties: type: type: string enum: - always_ask required: - type additionalProperties: false Objects_17: type: object properties: type: type: string enum: - custom name: type: string allOf: - minLength: 1 - maxLength: 128 - pattern: ^[A-Za-z0-9_-]+$ description: type: string allOf: - minLength: 1 input_schema: $ref: '#/components/schemas/ManagedAgentsCustomToolInputSchema' required: - type - name - description - input_schema additionalProperties: false Arrays_4: type: array items: type: string allOf: - minLength: 1 - maxLength: 255 allOf: - minItems: 1 - maxItems: 64 Objects_15: type: object properties: type: type: string enum: - approximate city: anyOf: - type: string - type: 'null' country: anyOf: - $ref: '#/components/schemas/ManagedAgentsIsoCountryCode' - type: 'null' region: anyOf: - type: string - type: 'null' timezone: anyOf: - $ref: '#/components/schemas/ManagedAgentsIanaTimeZone' - type: 'null' required: - type additionalProperties: false ManagedAgentsCustomToolInputSchema: type: object properties: type: type: string enum: - object properties: anyOf: - type: object additionalProperties: $ref: '#/components/schemas/JsonValue' - type: 'null' required: anyOf: - type: array items: type: string - type: 'null' required: - type additionalProperties: $ref: '#/components/schemas/JsonValue' description: JSON Schema for custom tool input parameters. ManagedAgentsIsoCountryCode: type: string allOf: - pattern: ^[A-Z]{2}$ ManagedAgentsIanaTimeZone: type: string allOf: - minLength: 1 - maxLength: 255 JsonValue: description: >- A value in the JSON data model: null, boolean, finite number, string, array, or object. securitySchemes: bearerAuth: type: http scheme: bearer ````