> ## Documentation Index > Fetch the complete documentation index at: https://docs.revoengine.com/llms.txt > Use this file to discover all available pages before exploring further. # Create a file upload session for a message attachment. > Create a file upload session for a message attachment. The request enforces thread membership and content visibility for the authenticated caller. ## OpenAPI ````yaml /api-reference/openapi.json post /api/v1/chat/threads/{threadId}/messages/{messageId}/uploads openapi: 3.0.0 info: title: RevoEngine Platform API description: Official RevoEngine Platform API documentation. version: 1.3.0 contact: name: Support email: support@revoengine.com termsOfService: https://docs.revoengine.com/tos servers: - url: https://api.revoengine.com description: Production security: [] tags: - name: Accounts description: Users, service accounts, API keys, status, and platform access. externalDocs: description: Identity and access guide url: https://docs.revoengine.com/operate/identity-and-access - name: Activity description: Snapshot-backed activity and version history. externalDocs: description: Observability guide url: https://docs.revoengine.com/operate/observability - name: Agent Memory description: Administrative access to durable Agent memory. externalDocs: description: Agent memory and workspaces guide url: https://docs.revoengine.com/ai/memory-and-workspaces - name: Agent Plugins description: Agent plugin definitions, synchronization, testing, and lifecycle. externalDocs: description: Agent plugins guide url: https://docs.revoengine.com/ai/plugins - name: Agents description: >- Agent definitions, runs, sessions, inboxes, memory, tools, workspaces, and lifecycle. externalDocs: description: Autonomous Agents guide url: https://docs.revoengine.com/ai/agents - name: Assistant description: >- Assistant threads, messages, responses, goals, reports, sharing, attachments, and control. externalDocs: description: Assistant guide url: https://docs.revoengine.com/ai/assistant - name: Automation description: >- Jobs, templates, schedules, events, webhooks, execution history, and lifecycle. externalDocs: description: Automation guide url: https://docs.revoengine.com/operate/automation - name: Chat description: Collaborative chat threads, messages, reactions, uploads, and attachments. externalDocs: description: Team Chat guide url: https://docs.revoengine.com/operate/chat - name: Component deployments description: >- Custom Node.js runtime deployment attempts, readiness, activation, and rollback. externalDocs: description: Custom Node.js guide url: https://docs.revoengine.com/build/custom-nodejs - name: Components description: Components, elements, versions, validation, activation, and lifecycle. externalDocs: description: Components guide url: https://docs.revoengine.com/build/components - name: Config description: Instance configuration, usage, logs, and cache administration. externalDocs: description: Instance settings guide url: https://docs.revoengine.com/platform/instance-settings - name: Database Cache description: Instance Database cache values and statistics. externalDocs: description: Database Cache guide url: https://docs.revoengine.com/operate/database-cache - name: Database Views description: Database Views, previews, refreshes, exports, and controlled data actions. externalDocs: description: Database Views guide url: https://docs.revoengine.com/operate/database-views - name: Databases description: Database definitions, data, audits, exports, cloning, and lifecycle. externalDocs: description: Databases guide url: https://docs.revoengine.com/operate/databases - name: Endpoints description: >- Endpoint definitions, activation, validation, generated OpenAPI, and statistics. externalDocs: description: Endpoints guide url: https://docs.revoengine.com/operate/endpoints - name: Files description: Compatibility file listing, preview, download, and deletion operations. externalDocs: description: Files compatibility guide url: https://docs.revoengine.com/operate/files - name: Groups description: Groups, membership, avatars, and lifecycle. externalDocs: description: Groups guide url: https://docs.revoengine.com/operate/groups - name: Me description: Current user profile, keys, avatar, and session information. externalDocs: description: Authentication guide url: https://docs.revoengine.com/developers/authentication - name: Preferences description: User and instance preference values. externalDocs: description: Platform UI guide url: https://docs.revoengine.com/platform/ui-tour - name: Role Groups description: Role groups, members, assigned roles, and lifecycle. externalDocs: description: Permissions guide url: https://docs.revoengine.com/operate/permissions - name: Roles description: Available platform roles and role details. externalDocs: description: Permissions guide url: https://docs.revoengine.com/operate/permissions - name: Search description: Cross-domain search over objects visible to the caller. externalDocs: description: Search and discovery guide url: https://docs.revoengine.com/platform/search - name: Secrets description: >- Secret definitions, revisions, activation, reveal, disable, and destruction. externalDocs: description: Secrets guide url: https://docs.revoengine.com/operate/secrets - name: Storage description: >- Storage workspaces, folders, objects, upload sessions, signed access, and lifecycle. externalDocs: description: Storage guide url: https://docs.revoengine.com/operate/storage externalDocs: description: Documentation url: https://docs.revoengine.com paths: /api/v1/chat/threads/{threadId}/messages/{messageId}/uploads: post: tags: - Chat summary: Create a file upload session for a message attachment. description: >- Create a file upload session for a message attachment. The request enforces thread membership and content visibility for the authenticated caller. operationId: ChatController_createUploadSession parameters: - name: threadId required: true in: path schema: type: string - name: messageId required: true in: path schema: type: string requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateStorageUploadSessionDto' responses: '200': description: OK. security: - bearer: [] components: schemas: CreateStorageUploadSessionDto: type: object properties: retention: description: >- Retention for the finalized file. Duration starts at finalization; null means no expiration. nullable: true type: object allOf: - $ref: '#/components/schemas/StorageRetentionDto' parentStorageEntryId: type: string description: >- Parent folder id. Required for create mode when uploading into a folder. example: 00000000-0000-4000-8000-000000000000 storageProviderConfigId: type: string description: >- Optional configured storage id for root-level uploads. Omit for managed default storage. Ignored when parentStorageEntryId is provided or when replacing an existing file. example: 00000000-0000-4000-8000-000000000001 replaceStorageEntryId: type: string description: Existing storage entry id to replace instead of creating a new file. example: 00000000-0000-4000-8000-000000000002 replaceExpectedVersion: type: number description: >- Expected current version of the file being replaced. The upload is rejected if the file changed after overwrite confirmation. example: 3 minimum: 0 name: type: string description: File name. Required for create mode. example: contracts.csv contentTypeHint: type: string description: Expected content type. example: text/csv sizeHint: type: number description: Expected size in bytes. example: 1048576 minimum: 0 tier: type: string description: >- Logical storage lifecycle tier. Select only when creating a new file or upload session; existing files keep their tier. HOT: Active files used in live workflows, previews, and frequent downloads. WARM: Completed or less-active business files that are still occasionally accessed. COLD: Compliance snapshots, historic imports, and retained evidence that is rarely opened. FROZEN: Deep archive or legal-hold data kept mainly for audit or recovery obligations. enum: - HOT - WARM - COLD - FROZEN example: HOT uploadMode: type: string description: >- Upload mode. Use "direct" for provider resumable uploads, "chunked" for explicit numbered parts, and "incremental" for server-assigned part numbering by default. Incremental sessions can still re-upload a specific part number when repairing an upload. enum: - direct - chunked - incremental example: incremental computeStats: type: string description: Default post-finalize compute mode for this upload session. enum: - none - sync - async example: async metadata: type: object description: >- File metadata. Values may use any JSON type. Maximum 16 KiB and 64 top-level keys. Top-level keys starting with "__" are reserved for backend use. example: scope: integration source: sdk refId: type: string description: Optional external reference id. refType: type: string description: Optional external reference type. refVer: type: number description: Optional external reference version. restricted: type: boolean description: Whether the finalized entry should be restricted. groups: description: Explicit allowed group ids for the finalized entry. type: array items: type: string users: description: Explicit allowed user ids for the finalized entry. type: array items: type: string StorageRetentionDto: type: object properties: ttlSeconds: type: number description: >- Positive lifetime in seconds. The lifetime starts when the file is finalized. minimum: 1 expiresAt: type: string description: Absolute future expiration timestamp in ISO 8601 format. example: '2026-08-01T12:00:00.000Z' securitySchemes: bearer: scheme: bearer bearerFormat: JWT description: Bearer JWT token or API Key (sk-*). type: http ````