> ## Documentation Index > Fetch the complete documentation index at: https://checkfu.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Download one file a Session produced > Returns the exact bytes of one Session file, selected by its absolute output path, as `application/octet-stream`. The file must appear in listSessionFiles with `kind: "captured"`; an excluded file, an unknown path, and an erased body are one not-found, so retention state is never inferable from a read. Files are captured at settlement, so a listed file is immediately readable — there is no indexing delay to retry through. `offset` and `length` read one byte range and are supplied together — either one alone is a malformed request, since a defaulted half would decide on your behalf how much of the body you receive. `length` is at most 8388608 (8 MiB), the most one response carries. The range is served exactly or not at all: the response always holds exactly `length` bytes starting at `offset`, and a range that runs past the end of the body is a bare not-found rather than a short read. Size ranges from the listing — every `captured` entry names its exact `size` — because that refusal deliberately names nothing. The same 8 MiB ceiling bounds a read with NO range: a larger body is refused as a malformed request naming its size and this ceiling, rather than served or silently truncated. Current Runners can capture one file through 67108864 bytes (64 MiB), so use successive exact ranges to reconstruct a larger captured file. Each range currently streams the governed body from byte 0 and discards everything before `offset`, so a file read in N equal parts moves roughly N/2 times its bytes; this is bounded but callers should choose the largest useful range. 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 get /v1/sessions/{id}/files/content openapi: 3.1.0 info: title: Checkfu API version: '2026-08-27' 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: 2026-08-27); 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: sandboxProfiles - 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: skillProposals - name: instructionProposals - name: catalog - name: concepts - name: support - name: connections - name: connectionVaults - name: connectionAssignments - name: connectedRuntimes - name: projects - 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: webhookEndpoints - name: integrationGateway - name: agentDeployments - name: workEnvironments - name: computers - name: computerScreens - name: computerBrowserObservations - name: computerBrowserActions - name: environments - name: vaults - name: apiMcp - name: a2a paths: /v1/sessions/{id}/files/content: get: tags: - sessions summary: Download one file a Session produced description: >- Returns the exact bytes of one Session file, selected by its absolute output path, as `application/octet-stream`. The file must appear in listSessionFiles with `kind: "captured"`; an excluded file, an unknown path, and an erased body are one not-found, so retention state is never inferable from a read. Files are captured at settlement, so a listed file is immediately readable — there is no indexing delay to retry through. `offset` and `length` read one byte range and are supplied together — either one alone is a malformed request, since a defaulted half would decide on your behalf how much of the body you receive. `length` is at most 8388608 (8 MiB), the most one response carries. The range is served exactly or not at all: the response always holds exactly `length` bytes starting at `offset`, and a range that runs past the end of the body is a bare not-found rather than a short read. Size ranges from the listing — every `captured` entry names its exact `size` — because that refusal deliberately names nothing. The same 8 MiB ceiling bounds a read with NO range: a larger body is refused as a malformed request naming its size and this ceiling, rather than served or silently truncated. Current Runners can capture one file through 67108864 bytes (64 MiB), so use successive exact ranges to reconstruct a larger captured file. Each range currently streams the governed body from byte 0 and discards everything before `offset`, so a file read in N equal parts moves roughly N/2 times its bytes; this is bounded but callers should choose the largest useful range. 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.getSessionFile parameters: - name: id in: path schema: $ref: '#/components/schemas/SessionId' required: true - name: checkfu-version in: header schema: type: string enum: - '2026-08-27' required: true - name: path in: query schema: $ref: '#/components/schemas/SessionOutputPath' required: true - name: offset in: query schema: type: integer minimum: 0 maximum: 9007199254740991 required: false - name: length in: query schema: type: integer minimum: 1 maximum: 8388608 required: false responses: '200': description: Success content: application/octet-stream: schema: type: string format: binary 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' '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: $ref: '#/components/schemas/RuntimeInternalError' security: - bearerAuth: [] components: schemas: SessionId: type: string allOf: - pattern: ^sess_[0-9a-f]{32}$ SessionOutputPath: type: string 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. 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. securitySchemes: bearerAuth: type: http scheme: bearer ````