"""Application error hierarchy.

Every expected failure is a subclass of :class:`LedgerlyError`, so the CLI
layer can translate failures into stable exit codes instead of inspecting
message text (single source of truth for error semantics).
"""

__all__ = ["ConflictError", "LedgerlyError", "NotFoundError", "ValidationError"]


class LedgerlyError(Exception):
    """Base class for all expected Ledgerly failures."""


class ValidationError(LedgerlyError):
    """Input does not satisfy a domain rule (R1-R10)."""


class NotFoundError(LedgerlyError):
    """The requested entity does not exist (R8, R12)."""


class ConflictError(LedgerlyError):
    """The request conflicts with current state (e.g. a category in use, R9)."""