"""Controller DB layer.

SQLAlchemy 2.0 declarative schema for the workflows, attempts,
events, flake-history, and ci-observations tables. The same schema
serves SQLite (tests + local dev) and Postgres (production; multi-
machine workers per plan v5).

The DB connection is configured by ``CLEVERAGENTS_DB_URL``:
    postgresql+psycopg2://user@host:5432/cleveragents
    sqlite:///./controller.db
    sqlite:///:memory:           (tests)

The dequeue helper (``dequeue.py``) abstracts over the two dialects'
different concurrency primitives:
- Postgres: ``SELECT … FOR UPDATE SKIP LOCKED``
- SQLite: ``BEGIN IMMEDIATE`` + serialized UPDATE
"""

from .models import (
    Base,
    CIObservation,
    ControllerEvent,
    FlakeHistory,
    Workflow,
    WorkflowAttempt,
)
from .session import (
    build_engine,
    create_all,
    session_scope,
)
from .dequeue import (
    DequeueResult,
    dequeue_one,
)
from .payload_guard import (
    PayloadTooLargeError,
    enforce_input_payload_size,
)

__all__ = [
    # models
    "Base",
    "CIObservation",
    "ControllerEvent",
    "FlakeHistory",
    "Workflow",
    "WorkflowAttempt",
    # session
    "build_engine",
    "create_all",
    "session_scope",
    # dequeue
    "DequeueResult",
    "dequeue_one",
    # payload guard
    "PayloadTooLargeError",
    "enforce_input_payload_size",
]