class AgentError(Exception):
    """Base error with a stable public code."""

    code = "AGENT_INTERNAL_ERROR"
    status_code = 500
    retryable: bool | None = False

    def __init__(self, message: str) -> None:
        super().__init__(message)
        self.message = message
        declared = type(self).retryable
        self.retryable = self.status_code >= 500 if declared is None else declared

    @property
    def is_retryable(self) -> bool:
        return bool(self.retryable)


class ValidationAgentError(AgentError):
    code = "AGENT_INPUT_INVALID"
    status_code = 422


class UnauthorizedAgentError(AgentError):
    code = "AUTHENTICATION_REQUIRED"
    status_code = 401


class AgentTypeNotFoundError(ValidationAgentError):
    code = "AGENT_TYPE_NOT_FOUND"
    status_code = 404


class ForbiddenAgentError(AgentError):
    code = "AGENT_PERMISSION_DENIED"
    status_code = 403


class OnboardingRequiredError(ForbiddenAgentError):
    code = "ONBOARDING_REQUIRED"


class ConflictAgentError(AgentError):
    code = "RUN_NOT_CANCELLABLE"
    status_code = 409


class IdempotencyConflictError(ConflictAgentError):
    code = "IDEMPOTENCY_CONFLICT"


class RecoverableAgentError(AgentError):
    code = "DEPENDENCY_UNAVAILABLE"
    status_code = 503
    retryable = True


class RunLeaseLostError(ConflictAgentError):
    code = "RUN_NOT_CANCELLABLE"


class ResourceNotFoundError(AgentError):
    code = "SESSION_NOT_FOUND"
    status_code = 404


class RunNotFoundError(ResourceNotFoundError):
    code = "RUN_NOT_FOUND"


class InvalidCursorError(AgentError):
    code = "INVALID_CURSOR"
    status_code = 400


class RateLimitedError(AgentError):
    code = "RATE_LIMITED"
    status_code = 429
    retryable = True


class SseNotAcceptableError(AgentError):
    code = "SSE_NOT_ACCEPTABLE"
    status_code = 406