LangChain

MirAPI exposes an OpenAI-compatible endpoint, so LangChain’s ChatOpenAI class works with it directly and you do not need a dedicated integration package. Point base_url at MirAPI and call any chat model in the catalog, such as deepseek-chat.

What you need

Element	Value
Base URL	`https://api.mirapi.ai/v1`
API key	`sk-...` (set as `MIRAPI_API_KEY`)
Model	`deepseek-chat`

Install

pip install langchain-openai

npm install @langchain/openai

Configure

Python:

import os
from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    base_url="https://api.mirapi.ai/v1",
    api_key=os.environ["MIRAPI_API_KEY"],
    model="deepseek-chat",
)

TypeScript:

import { ChatOpenAI } from "@langchain/openai";

const llm = new ChatOpenAI({
  model: "deepseek-chat",
  apiKey: process.env.MIRAPI_API_KEY,
  configuration: {
    baseURL: "https://api.mirapi.ai/v1",
  },
});

Verify with a message

response = llm.invoke("Reply with exactly: connected to MirAPI")
print(response.content)

The output should contain connected to MirAPI.

Stream responses

for chunk in llm.stream("Count from 1 to 5."):
    print(chunk.content, end="")

const stream = await llm.stream("Count from 1 to 5.");
for await (const chunk of stream) {
  process.stdout.write(chunk.content as string);
}

Streaming uses standard SSE and ends with data: [DONE], which LangChain handles for you.

Tool calling

from langchain_core.tools import tool

@tool
def add(a: int, b: int) -> int:
    """Add two integers."""
    return a + b

llm_with_tools = llm.bind_tools([add])
response = llm_with_tools.invoke("What is 3 + 5?")
print(response.tool_calls)

bind_tools maps to the OpenAI tools/tool_choice format. The model must support tool calling, so check its capability flag in the model catalog.

Structured output

from pydantic import BaseModel

class Recipe(BaseModel):
    name: str
    ingredients: list[str]

structured = llm.with_structured_output(Recipe)
recipe = structured.invoke("Suggest a simple pasta recipe")
print(recipe)

Structured output maps to response_format (json_schema / JSON mode). The model must support JSON output.

Parameters

Parameter	Purpose
`model`	Model ID, verbatim from `GET /v1/models`
`temperature`	Sampling temperature
`max_tokens`	Cap on output tokens
`streaming`	Enable SSE streaming
`reasoning_effort`	Reasoning intensity (reasoning-capable models)
`response_format`	Structured output (JSON mode / JSON Schema)
`tools` / `tool_choice`	Tool calling

Reasoning tokens are billed as output. Prompt caching is automatic for OpenAI-compatible models, and cache reads are cheaper than regular input.

Errors and troubleshooting

Status	Meaning	Action
401	Missing, invalid, or unknown key	Fix the API key
403	Key valid but rejected (empty balance, model whitelist, quota, IP allowlist)	Resolve the cause, then retry
413	Payload too large	Reduce the request size
429	Rate limited (no `Retry-After` header)	Jittered exponential backoff: 1s → 2s → 4s, cap ~30s
500	Gateway or upstream failure	Idempotent requests are safe to retry

Errors use the OpenAI envelope {"error":{"message","type","param","code"}}, with type set to new_api_error (gateway) or upstream_error (upstream). Each message ends with a request ID; include it in support tickets. The gateway does not retry for you.

Billing

Chat usage is billed per token, with separate prices for input, output, and cache reads. Cache reads are cheaper than regular input, and reasoning tokens are billed as output. MirAPI uses a prepaid USD balance with no subscription and no monthly fee, and the balance never expires. When the balance runs out, requests return 403; top up and the same key works again immediately.

Troubleshooting

Keep /v1 in base_url. LangChain appends /chat/completions to the base URL.
Use model names verbatim from GET /v1/models; the vendor/ prefix is for Platform browsing only and is not part of the API name.
403 with a valid key usually means the model is not whitelisted or the balance is exhausted.
429 has no Retry-After header, so implement backoff yourself.