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The Python SDK (opentracy) is the native entry point. Use it if you’re starting a new project or if you want features (auto-routing, distillation, trace ingestion) that aren’t part of the OpenAI API shape.

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Install

pip install opentracy
One install pulls a platform-specific wheel with the Go engine binary, the ONNX embedder, and pre-trained routing weights bundled in. No extras needed for the core path. 
pip install "opentracy[distill]"    # adds training deps (torch, unsloth, peft, trl)
pip install "opentracy[research]"   # adds sentence-transformers for the Python router backend
pip install "opentracy[server]"     # adds FastAPI + ClickHouse for self-hosting
pip install "opentracy[anthropic]"  # native Anthropic SDK path
pip install "opentracy[all]"        # everything

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The four things you’ll do

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1. One-off completion

Just a chat completion, no routing, no trace. 
import opentracy as ot

resp = ot.completion(
    model="openai/gpt-4o-mini",
    messages=[{"role": "user", "content": "What's 2+2?"}],
    temperature=0,
)
print(resp.choices[0].message.content)
Full API: completion reference.

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2. Explicit router with fallbacks

When you want deterministic rules (“try GPT-4o first, then Claude, then DeepSeek”), use the Router class: 
router = ot.Router(
    model_list=[
        {"model_name": "smart", "model": "openai/gpt-4o"},
        {"model_name": "smart", "model": "anthropic/claude-sonnet-4-6"},
    ],
    fallbacks=[{"smart": ["deepseek/deepseek-chat"]}],
    strategy="round-robin",   # or "least-cost", "lowest-latency", "weighted-random"
    num_retries=2,
    timeout=60,
)

resp = router.completion(
    model="smart",   # logical alias, resolved to one of the deployments
    messages=[{"role": "user", "content": "..."}],
)
Full API: Router reference.

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3. Semantic auto-router

Load the pre-trained router once; it picks the right model per prompt: 
auto = ot.load_router(cost_weight=0.5)

decision = auto.route("Write a haiku about autumn")
print(decision.selected_model)      # e.g. "ministral-3b-latest"
print(decision.cluster_id)          # e.g. 87
print(decision.expected_error)      # e.g. 0.212
print(decision.all_scores)          # full score dict
Combined with ot.completion this becomes a cost-optimizing client: 
def smart_call(prompt: str, api_key: str) -> str:
    d = auto.route(prompt)
    resp = ot.completion(
        model=d.selected_model,
        messages=[{"role": "user", "content": prompt}],
        api_key=api_key,
    )
    return resp.choices[0].message.content
Full API: load_router reference.

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4. Distillation

from opentracy import Distiller

d = Distiller(base_url="http://localhost:8000")

# Requires the engine + REST API to be running. See "Self-host" guide.
job = d.create(
    name="support-ticket-triage",
    dataset_id="ds_abc123",
    teacher_model="openai/gpt-4o",
    student_model="llama-3.2-1b",
    num_prompts=500,
    n_samples=4,
    training_steps=100,
)

job = d.wait(job["id"])
artifacts = d.artifacts(job["id"])
Full API: Distiller reference.

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Async

Everything that has a sync version has async: 
import asyncio
import opentracy as ot

async def main():
    resp = await ot.acompletion(
        model="openai/gpt-4o-mini",
        messages=[{"role": "user", "content": "hello"}],
    )
    print(resp.choices[0].message.content)

asyncio.run(main())
acompletion shares its request-preparation path with the sync version, so force_engine, force_direct, fallbacks, and engine-prefix handling all behave identically.

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Trace ingestion

If you have existing logs from another LLM provider and want to use them for dataset building or distillation in OpenTracy, you can import them directly: 
from opentracy import add_trace, add_traces, import_traces

# Single trace
add_trace({
    "prompt": "Classify: ...",
    "response": "billing",
    "model": "openai/gpt-4o",
    "total_cost_usd": 0.00025,
    "latency_ms": 340,
    "metadata": {"source": "legacy-log-export"},
})

# Batch
add_traces([{...}, {...}, {...}])

# From a JSONL file
import_traces("path/to/exported-traces.jsonl")

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Engine routing opt-in

By default the SDK calls providers directly. To route through an OpenTracy engine (for observability, aliases, etc.), set the env var once: 
export OPENTRACY_ENGINE_URL="http://localhost:8080"
From that point on, ot.completion(...) routes through the engine. Per-call overrides: 
# Always engine (even if OPENTRACY_ENGINE_URL is unset):
ot.completion(..., force_engine=True)

# Always direct (even if OPENTRACY_ENGINE_URL is set):
ot.completion(..., force_direct=True)
Why isn’t this automatic? Because silently routing through whatever happens to be listening on localhost:8080 is a footgun. Opt-in is explicit.

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13 providers via create_client

If you want a first-class LLMClient object (for profiling, or to fit into custom routing code), create_client covers every provider: 
c = ot.create_client("openai",   "gpt-4o-mini")       # dedicated class
c = ot.create_client("deepseek", "deepseek-chat")     # UnifiedClient wrapper
c = ot.create_client("together", "meta-llama/Llama-3")# UnifiedClient wrapper

out = c.generate("Hello", max_tokens=64, temperature=0.0)
print(out.text, out.latency_ms, out.tokens_used)
Five providers have dedicated classes (OpenAI, Anthropic, Google, Groq, Mistral); the remaining seven (DeepSeek, Perplexity, Cerebras, Sambanova, Together, Fireworks, Cohere) route through a UnifiedClient that speaks the OpenAI-chat protocol. Bedrock is registered but raises a clear error on construction — AWS SigV4 is not handled by UnifiedClient yet; use ot.completion(force_engine=True) instead.

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Public API — the 18 names

Everything import opentracy as ot exposes publicly: 
# Core
ot.completion, ot.acompletion, ot.Router, ot.ModelResponse, ot.StreamChunk, ot.parse_model
# Multi-provider
ot.create_client, ot.LLMResponse
# Pricing
ot.model_cost, ot.get_model_info, ot.supported_models
# Trace ingestion
ot.add_trace, ot.add_traces, ot.import_traces
# Distillation
ot.Distiller, ot.TrainingClient, ot.DistillerError
# Version
ot.__version__
Legacy research APIs (load_router, UniRouteRouter, RouterEvaluator, LLMJudge, …) resolve lazily via __getattr__ — they import the first time you touch them, so they don’t slow down the initial import opentracy.
Legacy code using import lunar_router as lr keeps working via a backwards-compat shim that redirects to opentracy and emits a DeprecationWarning. New code should use import opentracy as ot.

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Next

Self-host

Run engine + ClickHouse + UI locally or in your cloud.

API Reference

Every parameter and return value.