Live event stream (SSE)

Server-Sent Events stream of the job's live state. On connect the

client receives the current snapshot (a status event, the latest progress, and the most recent preview if any), then future updates. The stream ends after either the terminal status event or a terminal error event (see the error event below).

Live push only — NOT a replayable log: events carry no id, there is no Last-Event-ID resume, and frames emitted while disconnected are gone. Each progress event is a complete snapshot, so a single one fully re-syncs a reconnecting client; the authoritative state is always GET /api/v2/jobs/{id}.

OpenAPI

````yaml /openapi-v2.yaml get /api/v2/jobs/{id}/events openapi: 3.0.3 info: title: Comfy API v2 version: 2.0.0

description: |

The official, versioned HTTP API for running ComfyUI workflows from external applications: upload inputs, submit a workflow, observe execution, retrieve results.

Design principles:

Poll-first. Every capability is reachable via plain GET polling; the SSE stream is a live enhancement, never the source of truth.
Everything is resumable. Submission is idempotent; job state and outputs are retrievable by ID until expires_at.
UUID identity, content-addressed dedup. Assets are UUID-identified records over blobs keyed by a server-computed blake3 hash. The hash is nullable and may be computed lazily.
Follow links, don't build URLs. Responses embed follow-up URLs.

Additive changes only within v2; breaking changes require v3. servers:

url: http://127.0.0.1:8189 description: Self-hosted (comfy-api-proxy)
url: https://cloud.comfy.org description: Comfy Cloud
url: https://{deployment}.run.comfy.app description: Serverless deployment variables: deployment: description: >- DNS-safe deployment id (subdomain label). Staging uses {deployment}.stg.run.comfy.app. default: dep-1234abcd-56ef-7890-abcd-ef1234567890 security:
bearerAuth: []
{} tags:
name: assets description: UUID-identified records over content-addressed blobs.
name: jobs description: One execution of a workflow — durable, pollable, cancelable. paths: /api/v2/jobs/{id}/events: get: tags:
jobs summary: Live event stream (SSE) description: | Server-Sent Events stream of the job's live state. On connect the client receives the current snapshot (a status event, the latest progress, and the most recent preview if any), then future updates. The stream ends after either the terminal status event or a terminal error event (see the error event below).

$ref: '#/components/parameters/JobId' responses: '200': description: >- SSE stream; see x-sse-events for the event catalog. Sent with Cache-Control: no-cache, no-store, no-transform and X-Accel-Buffering: no so intermediaries neither cache, compress nor buffer the stream. content: text/event-stream: schema: type: string description: >- Stream of event:/data: frames. Data payloads are the JSON schemas listed in x-sse-events. '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '429': description: >- too_many_streams — the caller already has the maximum number of concurrent GET .../events streams open. Close an existing stream (or wait for one to reach a terminal status) before opening another; GET /api/v2/jobs/{id} remains available as a plain poll regardless of this limit. Or rate_limited, the caller past a request rate limit; retry after Retry-After. headers: Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '500': $ref: '#/components/responses/UpstreamError' '501': description: >- not_implemented — this deployment does not yet serve live event streaming. GET /api/v2/jobs/{id} remains available as a plain poll in the meantime. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '503': $ref: '#/components/responses/DeploymentLookupUnavailable' components: parameters: JobId: name: id in: path required: true schema: type: string example: 7f3d2c1b-9a8e-4d6f-b012-3c4d5e6f7a8b responses: Unauthorized: description: >- unauthorized: missing or invalid credentials. A credential that could not be checked answers auth_unavailable (503) instead. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' Forbidden: description: >- forbidden — authenticated but not allowed. On a serverless deployment, also sso_required — the key is valid, but the account must sign in through its organization's single sign-on, which does not accept this key; it can come back on any operation. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' NotFound: description: 'not_found.' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' UpstreamError: description: >- upstream_error — an unexpected failure reaching or processing the request in this implementation's backing services. The message is always a generic, safe-to-display string; implementation detail (the specific upstream, its error text, transport failures) is never included here — see each implementation's own error-mapping notes. Every operation in this contract can fail this way. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' DeploymentLookupUnavailable: description: >- On deployment-scoped surfaces, deployment_lookup_unavailable: the deployment this address names could not be looked up just now. The request was refused before it did anything (nothing was created, read, changed or canceled), so the same request can be sent again after Retry-After. Every operation at a deployment's address can answer this way. A job submit can also answer this 503 with database_unavailable: the job could not be saved just now and nothing was started, so the same request can be sent again after Retry-After. No other operation answers database_unavailable. On Comfy Cloud an asset upload can also answer this 503 with upload_busy: the server is busy with other uploads and nothing was stored, so the same upload can be sent again after Retry-After. Any operation can also answer this 503 with auth_unavailable: the credential could not be checked just now, so the same request can be sent again after Retry-After. A job status read can also answer it with output_unavailable: an output of the job could not be prepared just now, and the job is unchanged. A transient storage failure clears on a later read after Retry-After; an output whose stored address is broken answers it on every read until the platform repairs the output. headers: Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' headers: RetryAfter: schema: type: integer description: Seconds to wait before retrying. schemas: ErrorEnvelope: type: object description: | Shared error envelope with machine-readable codes. Core codes (v1): invalid_workflow (422), workflow_format_ui (422), missing_asset (422), hash_mismatch (409), blob_not_found (404), idempotency_key_reuse (422), upload_timed_out (422: an asset upload stopped sending or was too slow; retry from a faster connection), queue_full (429 + Retry-After), rate_limited (429 + Retry-After: the caller is past a request rate limit; retry), insufficient_credits (402), not_found (404), unauthorized (401), forbidden (403). Deployment-scoped surfaces add: deployment_not_ready (429 + Retry-After — the deployment can still reach ready; retry), deployment_unavailable (429 + Retry-After: the deployment is ready but its GPU provider is not taking work on it yet; retry), deployment_lookup_unavailable (503 + Retry-After, on any operation: the deployment the address names could not be looked up just now; nothing was done, so retry), database_unavailable (503 + Retry-After, only on a job submit: the job could not be saved just now and nothing was started, so retry), auth_unavailable (503 + Retry-After, on any operation: the credential could not be checked just now, which says nothing about the credential, so retry), output_unavailable (503 + Retry-After, only on a job status read: an output of the job could not be prepared just now; the job is unchanged, so retry after Retry-After, and report the job if it keeps answering), deployment_stopped (422 — terminal deployment state; a retry cannot succeed without operator action), invalid_request (422: a malformed asset upload or asset-from-hash field, or a jobs-list limit that is not a positive integer), validation_error (422, Cloud: an asset upload or asset-from-hash field was refused, e.g. a tag over the tag limits), content_blocked (451: content moderation flagged the asset's bytes) and sso_required (403: the key is valid, but the account must sign in through its organization's single sign-on, which does not accept this key). Comfy Cloud's asset upload adds invalid_content_type (422: the request is not multipart/form-data with a boundary), invalid_body (422: a malformed multipart body or upload field), validation_error (422: the platform refused the upload, for example an image over the size cap or a disallowed tag) and upload_busy (503 + Retry-After: the server is busy with other uploads and nothing was stored, so retry). Job labels add: metadata_invalid (422: a submitted metadata breaks a limit; details.key names the key, except for too many pairs, which has no details), metadata_not_supported (422: this surface keeps no job labels yet), invalid_metadata_filter (400) and invalid_cursor (400). A surface that does not list jobs yet answers not_implemented (501). A 429 is disambiguated by error.code alone; clients should treat any 429 + Retry-After as "back off and retry". required:
error properties: error: type: object required:
code
message properties: code: type: string example: invalid_workflow message: type: string example: 'Node 12 (KSampler): required input ''model'' is not connected' organization_id: type: string description: >- On sso_required: the organization whose single sign-on governs this key, the one that holds the account, else the one that holds the key's workspace. It is the organization query parameter of Comfy Cloud's single sign-on start; treat it as opaque. Absent when the organization is unknown, and on every other code. example: org_01HXYZEXAMPLE details: type: object nullable: true additionalProperties: true description: >- Machine-readable detail for the code. When it carries node_errors, that is keyed by node id and each value is a JobNodeError, the same shape as a job's error.node_errors, whether the refusal came at submit (for example unknown_node_class, a node class the deployment's build does not contain) or from ComfyUI after dispatch. With unknown_node_class errors it carries unknown_node_classes, the missing classes; with waits_for_browser errors, browser_wait_node_classes, the classes that wait for a browser. A submit refusal names at most fifty nodes. For invalid_node, invalid_inputs and invalid_class_type, when it found more than fifty, node_errors_truncated is true and malformed_node_count carries the full count; for waits_for_browser, browser_wait_node_count does. For unknown_node_class it names only nodes whose class is one of the at most ten listed in unknown_node_classes; when those nodes number more than fifty, node_errors_truncated is true and unknown_node_count is how many nodes have a listed class. Nodes whose class is past those ten are neither named nor counted. example: node_errors: '12': class_type: SomeCustomNode errors:
type: unknown_node_class message: >- this deployment's build does not contain the node class SomeCustomNode. unknown_node_classes:
SomeCustomNode securitySchemes: bearerAuth: type: http scheme: bearer description: >- Authorization: Bearer <credential>. The credential is one of: an account-scoped API key (comfyui-…), accepted on Cloud and serverless; a Comfy Cloud session JWT; or an OAuth access token issued for the Comfy Cloud resource. Which kinds a given deployment accepts is deployment configuration — an API key always works on Cloud and serverless, and a deployment that does not accept JWT bearers answers 401 with a message saying so. Self-hosted accepts unauthenticated requests by default and can be configured with a static bearer token.

````