Bursar Python SDK for AI credits and usage billing

The Python SDK for Bursar. It meters usage, prices operations, and manages balances against the shared canonical PostgreSQL schema and the same versioned configuration document as the JavaScript SDK. Python 3.12 and 3.13 are supported.

Installation

python -m pip install "bursar[postgres]"

Extras: postgres (default recommended), stripe or dodo for that payment provider, s3 (optional billing archive), google-adk (model-call admission and settlement plugin), and test (dev/test tooling).

Apply the SQL baseline before starting an application:

export BURSAR_MIGRATION_DATABASE_URL=postgresql://bursar_migrator@db.example.com/bursar
bursar migrate

bursar migrate applies the ordered SQL files, records checksums, and is safe to re-run. Use a dedicated migration principal; applications connect with a separate least-privilege runtime principal. See the CLI guide for the separate migration, operator, and application credentials.

Usage

from decimal import Decimal

from bursar import Bursar, PostgresStore

store = PostgresStore(
    database_url,
    tenant_id=tenant_id,
    provider_environment="test",
)
bursar = Bursar(credit_store=store)

grant = bursar.credits.add_credits(
    user_id,
    Decimal("500"),
    entry_type="purchase",
    idempotency_key="checkout:42",
)
charge = bursar.credits.deduct_credits(
    user_id,
    Decimal("20"),
    idempotency_key="job:42",
)
refund = bursar.credits.refund_credits(charge.entry_id, idempotency_key="refund:job:42")

page = bursar.credits.list_ledger_entries(user_id, limit=25)
while page.next_cursor is not None:
    page = bursar.credits.list_ledger_entries(user_id, limit=25, cursor=page.next_cursor)

LedgerEntry, LedgerCursor, and LedgerPage are available from bursar.credits.types; pagination is cursor-only. PostgresStore is the production, tenant-scoped store; CreditStore is the abstract base for custom implementations.

Publish one versioned configuration document through the facade — billing and auto-recharge read the same active document:

bursar.catalog.publish_and_activate(config)

Optional S3 and ClickHouse storage

PostgreSQL remains authoritative. S3 and ClickHouse are optional delivery targets, managed by create_bursar_runtime from bursar.storage:

from bursar.storage import BursarRuntimeOptions, create_bursar_runtime

runtime = create_bursar_runtime(
    BursarRuntimeOptions(
        postgres=os.environ["DATABASE_URL"],
        operator_postgres=os.environ["BURSAR_OPERATOR_DATABASE_URL"],
        tenant_id=os.environ["BURSAR_TENANT_ID"],
        provider_environment="test",
    )
)
runtime.start()
bursar = runtime.bursar

With no S3/ClickHouse configuration the runtime creates no background worker and analytics query PostgreSQL directly. See the storage guide for the full S3 and ClickHouse setup.

Development

cd python
uv sync --group dev        # runtime + dev/test deps
uv run pytest              # full suite; integration tests need Postgres
uv run ruff check src/ tests/ scripts/
uv run pyright src/ --warnings

Real-Postgres tests resolve DATABASE_URL when BURSAR_ALLOW_DATABASE_RESET=1, else spin up a disposable PostgreSQL 17 + pg_partman 5 + pg_jsonschema 0.3 testcontainer. See CONTRIBUTING.md.

License

AGPL-3.0.