> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-comfy-docs-comfyapi-search.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Comfy Router capabilities and limits
> Choose Router or a partner proxy, plan for long-running calls, and understand recovery, rate limits, and asset storage.
Router supports synchronous and queued delivery. Synchronous delivery returns the finished result in one response. Queued delivery returns a request handle and is rolling out by workspace.
## What Router supports
| Requirement | Router support | Alternative or next step |
| ------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------- |
| Generate with one request | `POST /v2/models/{provider}/{model}` returns the finished result. | Start with the [Quickstart](/development/comfy-router/quickstart). |
| Submit a request and collect it later | Supported through `POST /v2/models/{provider}/{model}/requests` and rolling out by workspace. | See [Queued delivery](/development/comfy-router/queue). |
| Show progress or stream output | Queued delivery reports queue state and can include queue position, but no percentage progress, streaming output, or preview frames. | Poll the returned `status_url`, or use a supported proxy operation for provider-specific progress. |
| Recover after a lost connection | After receiving a queued request handle, use its returned URLs. If submission is interrupted before that, retry with the same idempotency key. Synchronous calls can sometimes be collected the same way. | Preserve the idempotency key and follow [retry guidance](/development/comfy-router/api#retry-outcomes). |
| Reconcile Comfy charges | No universal Comfy cost or credit-balance field on the response. | Use [workspace billing](https://platform.comfy.org). |
| Store results permanently | Asset URLs can expire, including rehosted and replayed URLs. | Download the assets; see [result assets](/development/comfy-router/reference#result-assets). |
## Queued delivery availability
Queued delivery returns a `request_id` and URLs for status, result collection, and cancellation. It is rolling out by workspace; workspaces without access receive `403` with `not_enabled`. Cancellation is best effort, and Router does not provide a completion webhook. See [Queued delivery](/development/comfy-router/queue) for examples and the full lifecycle.
## Synchronous calls are cut off at a server deadline
Router's default deadline is **10 minutes**, configurable by the deployment. Set your client timeout above it so Router can return its error and request ID first.
`504` / `deadline_exceeded` means Router stopped waiting; `504` / `provider_timeout` means the provider timed out. A timeout or lost connection does not prove that a generation was unbilled, and it does not cancel accepted provider work. Read [timeouts and collection](/development/comfy-router/api#timeouts-and-collection) before retrying.
## Recovery depends on the provider
Router can retain a provider handle for an accepted submit-and-poll generation. Reuse the same `Idempotency-Key` to collect it later; completed replayable responses can also come from the key record.
Not every disconnected call is recoverable. Preserve the request and key before sending, then use the [retry outcome table](/development/comfy-router/api#retry-outcomes). A new key creates a new call and may incur another charge.
## Requests are rate limited per caller
| Response | Cause | Action |
| ------------------------------------ | -------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------- |
| `429` / `concurrency_limit_exceeded` | Too many concurrent calls, or insufficient headroom under the committed-spend ceiling. | Reduce concurrent work. The spend headers distinguish the spend ceiling from the call-count limit. |
| `429` / `rate_limited` | The request allowance is exhausted. | Wait for `Retry-After` before retrying. |
The request-rate limit applies to invocation and catalog/schema reads, including requests refused before generation. It follows the authenticated caller, not the source IP. Calls with the caller's provider key are exempt; provider limits still apply.
Cache catalog and schema reads. Revalidate schemas with `ETag` and `If-None-Match`. See [Headers](/development/comfy-router/headers) for retry and committed-spend fields.
## No live progress while a request runs
Synchronous delivery returns only the final response. Queued delivery exposes queue state and can include queue position, but neither mode provides streamed tokens, server-sent events, percentage updates, or intermediate preview frames. A provider's internal progress is not forwarded.
Show an indeterminate progress indicator after a queued request begins running. If you need provider-specific progress or streaming, use a partner-proxy operation that exposes it.
## Comfy charges and usage
The response can contain provider usage or cost fields. They do not represent a universal Comfy charge. `X-Comfy-Credits-Used` is optional and is not replayed. Use the Comfy platform for balances, usage, and invoices.
The catalog provides billing facts, including `billing.charges_on_policy_rejection`, rather than prices. Handle `yes`, `no`, and `unknown` explicitly. See [billing](/development/comfy-router/api#model-billing-facts).
## Router does not cover every partner operation
Router runs models. File uploads, account reads, asset management, streaming, and provider job controls can require partner-proxy routes under `/proxy/…`. Check the [Comfy API specification](/openapi-v2.yaml); support varies by provider.
## Model outputs and stored assets
Input and output fields vary by model. Moving from a provider SDK or proxy can change both the route and how you read the result.
Some assets are rehosted on Comfy storage; others are provider URLs or inline bytes. See [Result assets](/development/comfy-router/reference#result-assets) for lifetimes and replay behavior.
## Next
Generate your first image through Comfy Router.
Choose a model, inspect its schema, and handle results and retries.