> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apiyi.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Seed 2.1 Turbo Responses API Reference
> Seed 2.1 Turbo (dola-seed-2-1-turbo-260628) Responses API reference and interactive playground: native multi-turn previous_response_id and chained explicit caching.
Use the Playground on the right: put `Bearer sk-your-api-key` in **Authorization**, fill in `input`, and send. In the response `output` array, `type: "reasoning"` items are thinking summaries — `type: "message"` is the actual answer.
For multi-turn conversations, pass the previous response's `id` (`resp_` prefix) as the next call's `previous_response_id` — no need to resend history. Explicit caching and thinking control are covered in the [Seed 2.1 Turbo Overview](/en/api-capabilities/dola-seed-2-1-turbo/overview).
* A small `max_output_tokens` gets eaten by thinking, returning `status: "incomplete"` with **empty text** — start at 1500
* Explicit caching `caching: {"type": "enabled"}` only hits when **chained** via `previous_response_id`; merely repeating the same prefix never hits (and disables the implicit prefix cache too)
## Parameter Quick Reference
| Parameter | Type | Required | Default | Notes |
| ---------------------- | -------------- | -------- | ---------- | ------------------------------------------------------------------------------------ |
| `model` | string | ✓ | — | Fixed: `dola-seed-2-1-turbo-260628` |
| `input` | string / array | ✓ | — | String or message array (including `function_call_output` items) |
| `max_output_tokens` | int | | — | Output budget including thinking; 1500+ recommended |
| `reasoning.effort` | string | | — | `low` / `medium` / `high`; measured \~371 (low) vs \~1317 (high) reasoning tokens |
| `previous_response_id` | string | | — | Previous response id for native multi-turn; enables full-context explicit cache hits |
| `caching.type` | string | | `disabled` | `enabled` turns on explicit caching (requires chaining) |
| `store` | bool | | `true` | Store this response for later reference |
| `stream` | bool | | `false` | SSE event stream (`response.created` → `response.completed`) |
| `text.format` | object | | — | Structured output, supports `json_schema` + `strict` |
| `tools` | array | | — | Function-calling tool list (flat format) |
## Response Highlights
* When `status` is `incomplete`, check `incomplete_details.reason` (usually `length`: thinking ate the budget)
* Thinking spend: `usage.output_tokens_details.reasoning_tokens`
* Cache hits: `usage.input_tokens_details.cached_tokens` (chained turn 2 hit the full prior context in our tests, roughly halving latency)
* The response `caching` field echoes the cache mode actually in effect
## OpenAPI
````yaml api-reference/dola-seed-2-1-turbo-responses-openapi-en.yaml POST /v1/responses
openapi: 3.1.0
info:
title: Seed 2.1 Turbo Responses API
description: >
ByteDance Seed 2.1 Turbo (`dola-seed-2-1-turbo-260628`) — native Responses
API endpoint.
- Full Responses semantics: event stream, reasoning items, multi-turn via
`previous_response_id`
- **Explicit caching**: `caching: {"type": "enabled"}` combined with
`previous_response_id` chaining hits the entire previous context on turn 2
(measured: 7873 cached tokens, ~2x faster)
- Reasoning is on by default: a small `max_output_tokens` gets eaten by
thinking, yielding `status: incomplete` with empty text - use 1500+
- Supports `reasoning.effort` tiers, structured output (`text.format`), and
function calling
**Authentication**: add `Authorization: Bearer YOUR_API_KEY` header
**Get an API Key**: create a token in the APIYI console at
`api.apiyi.com/token`
version: 1.0.0
servers:
- url: https://api.apiyi.com
description: Primary endpoint
- url: https://vip.apiyi.com
description: Backup endpoint
security:
- bearerAuth: []
paths:
/v1/responses:
post:
tags:
- Text Generation
summary: Responses API with Seed 2.1 Turbo (native multi-turn / explicit cache)
description: >
Call the Responses API with `dola-seed-2-1-turbo-260628`.
- For multi-turn conversations pass `previous_response_id` instead of
resending history
- With `caching.enabled`, cache hits require `previous_response_id`
chaining; merely repeating the same prefix does not hit
operationId: createSeedResponse
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/SeedResponsesRequest'
example:
model: dola-seed-2-1-turbo-260628
input: Introduce yourself in one sentence
max_output_tokens: 1500
responses:
'200':
description: >-
Generation succeeded. The output array contains reasoning and
message items
content:
application/json:
schema:
$ref: '#/components/schemas/SeedResponsesResponse'
'400':
description: Invalid parameters
'401':
description: Unauthorized - invalid API Key
'429':
description: Rate limit exceeded or insufficient balance
'503':
description: >-
Wrong model name or no available channel for your group (this model
returns 503 instead of 404 for unknown model names)
security:
- bearerAuth: []
components:
schemas:
SeedResponsesRequest:
type: object
required:
- model
- input
properties:
model:
type: string
description: Model ID, fixed to dola-seed-2-1-turbo-260628
enum:
- dola-seed-2-1-turbo-260628
default: dola-seed-2-1-turbo-260628
input:
type: string
description: >-
Input content. Either a string or a message array ([{role, content},
...], including function_call_output items)
example: Introduce yourself in one sentence
max_output_tokens:
type: integer
description: >-
Max output tokens (thinking included). Too small yields incomplete
with empty text - use 1500+
default: 1500
reasoning:
type: object
description: >-
Thinking depth control. Measured: effort low ~371, high ~1317
reasoning tokens
properties:
effort:
type: string
enum:
- low
- medium
- high
previous_response_id:
type: string
description: >-
Previous response id (resp_ prefix) for native multi-turn; combine
with caching.enabled for explicit cache hits
caching:
type: object
description: >-
Explicit cache switch. enabled only hits when chained via
previous_response_id
properties:
type:
type: string
enum:
- enabled
- disabled
store:
type: boolean
description: >-
Whether to store this response for later previous_response_id
reference
stream:
type: boolean
description: >-
Stream via SSE (response.created → response.output_text.delta →
response.completed)
default: false
text:
type: object
description: >-
Structured output. Supports {"format": {"type": "json_schema", name,
strict, schema}}
tools:
type: array
description: >-
Function-calling tool list (flat Responses format: {type, name,
description, parameters})
items:
type: object
SeedResponsesResponse:
type: object
properties:
id:
type: string
description: >-
Response ID (resp_ prefix), usable as the next turn's
previous_response_id
status:
type: string
description: >-
completed / incomplete (incomplete when thinking eats the token
budget)
output:
type: array
description: >-
Output items: reasoning (thinking summary), message (text),
function_call, etc.
items:
type: object
usage:
type: object
description: >-
Usage. output_tokens_details.reasoning_tokens = thinking spend;
input_tokens_details.cached_tokens = cache hits
caching:
type: object
description: The cache mode actually in effect for this request
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: API Key from the APIYI console
````