> ## Documentation Index > Fetch the complete documentation index at: https://docs.firedrill.run/llms.txt > Use this file to discover all available pages before exploring further. # Start the reserved interaction > Uses the exact reservation generation/version and current original owner. Only replayed=false authorizes one invocation. Persist invocation intent before sending; after a lost start response retry the same key to recover the receipt, never automatically invoke on replay. Request Tool access with the returned claim identity. ## OpenAPI ````yaml /api-reference/openapi.json post /v1/projects/{projectId}/runs/{hostedRunId}/interaction-claims/{claimId}/start openapi: 3.1.0 info: title: Firedrill Control API version: 1.0.0 description: >- The control plane for drills, drill runs, and the worlds they run in. Errors always carry the canonical envelope; unsafe operations require an Idempotency-Key; long work returns an operation resource. servers: - url: https://api.firedrill.run security: - controlCredential: [] paths: /v1/projects/{projectId}/runs/{hostedRunId}/interaction-claims/{claimId}/start: post: summary: Start the reserved interaction description: >- Uses the exact reservation generation/version and current original owner. Only replayed=false authorizes one invocation. Persist invocation intent before sending; after a lost start response retry the same key to recover the receipt, never automatically invoke on replay. Request Tool access with the returned claim identity. operationId: interactionClaims.start parameters: - name: projectId in: path required: true schema: type: string pattern: ^prj_[0-9a-z]{12,32}$ - name: hostedRunId in: path required: true schema: type: string pattern: ^hrun_[0-9a-z]{12,32}$ - name: claimId in: path required: true schema: type: string pattern: ^iclaim_[0-9a-z]{12,32}$ - name: Idempotency-Key in: header required: true schema: type: string minLength: 8 maxLength: 128 pattern: ^[A-Za-z0-9._:-]+$ requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/MutateInteractionClaimRequest' responses: '200': description: Original or newly accepted ownership receipt content: application/json: schema: $ref: '#/components/schemas/InteractionClaimResponse' '400': description: Canonical error envelope content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '401': description: Canonical error envelope content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '403': description: Canonical error envelope content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '404': description: Canonical error envelope content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '409': description: Canonical error envelope content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' default: description: Canonical error envelope content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' components: schemas: MutateInteractionClaimRequest: type: object properties: generation: type: integer minimum: 0 exclusiveMinimum: true maximum: 9007199254740991 expectedVersion: type: integer minimum: -9007199254740991 maximum: 9007199254740991 runnerId: type: string pattern: ^[A-Za-z0-9][A-Za-z0-9._:-]{0,159}$ required: - generation - expectedVersion - runnerId additionalProperties: false InteractionClaimResponse: type: object properties: claim: type: object properties: schemaVersion: type: number enum: - 1 claimId: type: string pattern: ^iclaim_[0-9a-z]{12,32}$ organizationId: type: string pattern: ^org_[0-9a-z]{12,32}$ projectId: type: string pattern: ^prj_[0-9a-z]{12,32}$ hostedRunId: type: string pattern: ^hrun_[0-9a-z]{12,32}$ interactionId: type: string minLength: 1 maxLength: 96 pattern: ^[a-z][a-z0-9]*(?:[-_][a-z0-9]+)*$ expectedRunRevision: type: integer minimum: 0 exclusiveMinimum: true maximum: 9007199254740991 runnerId: type: string pattern: ^[A-Za-z0-9][A-Za-z0-9._:-]{0,159}$ simulationWorkId: type: string pattern: ^simwork_[0-9a-z]{12,32}$ generation: type: integer minimum: 0 exclusiveMinimum: true maximum: 9007199254740991 version: type: integer minimum: -9007199254740991 maximum: 9007199254740991 state: type: string enum: - reserved - started - submitted - expired - uncertain - cancelled createdAtMs: type: integer minimum: -9007199254740991 maximum: 9007199254740991 updatedAtMs: type: integer minimum: -9007199254740991 maximum: 9007199254740991 expiresAtMs: type: integer minimum: -9007199254740991 maximum: 9007199254740991 startedAtMs: type: integer minimum: -9007199254740991 maximum: 9007199254740991 finishedAtMs: type: integer minimum: -9007199254740991 maximum: 9007199254740991 completionOperationId: type: string pattern: ^op_[0-9a-z]{12,32}$ required: - schemaVersion - claimId - organizationId - projectId - hostedRunId - interactionId - expectedRunRevision - runnerId - generation - version - state - createdAtMs - updatedAtMs - expiresAtMs additionalProperties: false replayed: type: boolean required: - claim - replayed additionalProperties: false ErrorEnvelope: type: object properties: code: type: string pattern: ^(control|world)\.[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$ message: type: string minLength: 1 correlationId: type: string minLength: 1 retryable: type: boolean retryAfterMs: type: integer exclusiveMinimum: 0 maximum: 9007199254740991 operationId: type: string source: type: string enum: - platform - simulated_provider issues: type: array items: type: object properties: path: type: string code: type: string message: type: string required: - path - code - message additionalProperties: false details: type: object propertyNames: type: string additionalProperties: {} evidence: type: object properties: sessionId: type: string runId: type: string journalSeq: type: integer minimum: 0 maximum: 9007199254740991 buildHash: type: string additionalProperties: false required: - code - message - correlationId - retryable - source additionalProperties: true securitySchemes: controlCredential: type: http scheme: bearer description: Opaque control credential ````