nozle-sdk 0.4.0

Nozle SDK — usage tracking, margin intelligence, and entitlement checks for AI billing

Nozle Python SDK

Backend-only Python SDK for Nozle billing, exact-decimal credits, Entity lifecycle, ledger usage, margin intelligence, and LLM usage capture. Version 0.4.0 mirrors the backend contract exposed by @nozle-js/node 0.4.0.

Install

pip install nozle-sdk

Python 3.9 through 3.13 are supported. The package is typed and includes py.typed.

Authentication

• pk_ publishable keys may call only plans().
• sk_ secret keys are required for every customer read, mutation, event, credit, Entity, usage, and margin operation.
• Protected operations reject pk_ locally before network I/O.

Keep secret keys on a trusted backend. This package is not a browser SDK. When a request originates in a browser, authenticate it in your backend and derive the Nozle customer_id from that authenticated user, team, or organization. Do not treat a browser-supplied customer ID as authoritative.

from nozle import Nozle

nozle = Nozle(
    api_key="sk_backend_...",
    base_url="https://api.nozle.ai",
    events_url="https://core.nozle.ai",
    timeout=15,
)

Public namespaces

The client exposes customers, credit_systems, credits, entities, usage, and margin.

Plans and checkout

plans = nozle.plans()

checkout = nozle.checkout(
    "customer-123",
    "pro",
    return_url="https://merchant.example/billing/complete",
)

Checkout can return any production transition shape:

• {"type": "stripe", "client_secret": "..."}
• {"type": "stripe", "url": "https://..."}
• {"type": "completed", "status": "..."}
• {"type": "scheduled", "status": "..."}

The deprecated success_url= argument remains an alias for return_url=. The SDK never sends both fields and rejects conflicting values.

Backend subscription creation remains available with nozle.subscribe(customer_id, plan_code). Both checkout and subscription creation require an sk_ key.

Customers and Credit Systems

customer = nozle.customers.upsert(
    "customer-123",
    name="Acme",
    email="[e-mail]",
)

# Follows every active Core page and returns one normalized list.
systems = nozle.credit_systems.list()

Customer and Entity credits

balance = nozle.credits.get_balance("customer-123", "ai_credits")
balances = nozle.credits.list_balances("customer-123")
operations = nozle.credits.list_operations(
    "customer-123",
    credit_system_code="ai_credits",
    limit=50,
    cursor=None,
)

entity_balance = nozle.credits.get_entity_balance(
    "customer-123", "user-42", "ai_credits"
)
entity_balances = nozle.credits.list_entity_balances("customer-123", "user-42")
entity_operations = nozle.credits.list_entity_operations(
    "customer-123", "user-42", limit=50
)

allocation = nozle.credits.allocate(
    "customer-123",
    "user-42",
    credit_system_code="ai_credits",
    amount="100.000000000001",
    idempotency_key="allocation-user-42-v1",
)

Every credit amount is returned as a string and is never converted to float. Allocation and deallocation amounts must be positive decimal strings with at most 12 decimal places. Mutation idempotency keys are mandatory and must fit within 255 UTF-8 bytes.

Entities

entity = nozle.entities.get("customer-123", "user-42")
page = nozle.entities.list("customer-123", status="active", limit=50)

result = nozle.entities.upsert(
    "customer-123",
    "user-42",
    status="active",
    name="Asha",
    metadata={"team": "support"},
    idempotency_key="entity-user-42-v1",
)

nozle.entities.suspend(
    "customer-123", "user-42", idempotency_key="suspend-user-42-v1"
)
nozle.entities.activate(
    "customer-123", "user-42", idempotency_key="activate-user-42-v1"
)

nozle.entities.bulk_upsert(
    "customer-123",
    [
        {"external_id": "user-42", "status": "active"},
        {"external_id": "user-43", "status": "suspended"},
    ],
    idempotency_key="entity-import-v1",
)

Entity IDs use UTF-8 byte limits, list limits are 1–100, and bulk upserts accept 1–500 unique Entity IDs.

Ledger usage

usage.check() is advisory and does not mutate a balance. usage.track() atomically records consumption and requires an idempotency key.

preview = nozle.usage.check(
    "customer-123",
    "agent_execution",
    entity_id="user-42",
    credit_system_code="ai_credits",
    properties={"model": "gpt-5"},
    occurred_at="2026-07-20T12:00:00.750Z",
)

consumption = nozle.usage.track(
    "customer-123",
    "agent_execution",
    entity_id="user-42",
    properties={"model": "gpt-5"},
    timestamp="2026-07-20T12:00:00.750Z",
    idempotency_key="execution-123",
)

The SDK does not automatically retry mutation requests. Retry only with the same idempotency key after deciding the failure is safe to retry.

Existing operations

nozle.track(
    "customer-123",
    "api_call",
    metadata={"tokens": 100},
    subscription_id="subscription-123",
)

entitlement = nozle.can("customer-123", "code_completion")
deduction = nozle.check_and_deduct("customer-123", "code_completion", credits=5)
health = nozle.ping()

summary = nozle.margin.summary()
by_customer = nozle.margin.by_customer()
trend = nozle.margin.trend(granularity="week")

If track() is called without subscription_id, the SDK resolves and caches the customer's single active subscription through Core.

OpenAI and Anthropic wrappers

Install an optional provider dependency:

pip install "nozle-sdk[openai]"
pip install "nozle-sdk[anthropic]"

from openai import OpenAI
from nozle import Nozle, wrap_openai

nozle = Nozle("sk_backend_...")
openai = wrap_openai(
    OpenAI(),
    nozle,
    customer_id="customer-123",
    metric_code="llm_tokens",
    feature="assistant",
)

response = openai.chat.completions.create(
    model="gpt-5",
    messages=[{"role": "user", "content": "Hello"}],
)

Synchronous clients, asynchronous clients, synchronous streams, and asynchronous streams are supported for OpenAI and Anthropic. The wrappers emit these event properties:

• model
• input_tokens
• output_tokens
• latency_ms
• optional feature

Provider failures are propagated. If the provider succeeds but Nozle tracking fails, the successful provider response or completed stream is preserved and a NozleTrackingWarning is emitted without credential-bearing error details.

Errors

NozleAPIError exposes operation, status_code, and credential-safe response_details. Local contract failures use NozleValidationError or NozleAuthenticationError; transport failures use NozleTransportError. Exception messages redact API keys and secret-shaped response fields.

License

AGPL-3.0-or-later