feat(errors): add redacted typed failures

smartthings_local/errors.py

@@ -0,0 +1,103 @@
+"""Public, redacted exception types for smartthings-local."""
+
+__all__ = [
+    'AuthenticationError',
+    'AuthorizationError',
+    'BlockwiseError',
+    'EndpointError',
+    'MalformedMessageError',
+    'ObserveError',
+    'ProbeError',
+    'SessionClosedError',
+    'SessionError',
+    'SessionTimeoutError',
+    'SmartThingsLocalError',
+]
+
+
+class SmartThingsLocalError(Exception):
+    """Base class for classified library failures.
+
+    Subclasses expose a stable ``code`` and a fixed, non-sensitive message.
+    They intentionally do not accept arbitrary detail because backend errors
+    can contain remote endpoints, local paths, or credential metadata.
+    """
+
+    code = 'smartthings_local_error'
+    message = 'SmartThings Local operation failed'
+
+    def __init__(self):
+        super().__init__(self.message)
+
+    def __repr__(self):
+        return f'{type(self).__name__}(code={self.code!r})'
+
+
+class EndpointError(SmartThingsLocalError, OSError):
+    """An endpoint could not be resolved, bound, or connected."""
+
+    code = 'endpoint'
+    message = 'endpoint operation failed'
+
+
+class ProbeError(SmartThingsLocalError, ConnectionError):
+    """A DTLS probe failed before producing a protocol result."""
+
+    code = 'probe'
+    message = 'DTLS probe failed'
+
+
+class SessionError(SmartThingsLocalError, ConnectionError):
+    """A connected-session operation failed."""
+
+    code = 'session'
+    message = 'session operation failed'
+
+
+class AuthenticationError(SessionError):
+    """The peer or local credentials could not be authenticated."""
+
+    code = 'authentication'
+    message = 'authentication failed'
+
+
+class AuthorizationError(SmartThingsLocalError, PermissionError):
+    """The authenticated peer is not authorized for an operation."""
+
+    code = 'authorization'
+    message = 'operation is not authorized'
+
+
+class SessionTimeoutError(SmartThingsLocalError, TimeoutError):
+    """A bounded session operation exceeded its deadline."""
+
+    code = 'timeout'
+    message = 'session operation timed out'
+
+
+class SessionClosedError(SessionError):
+    """An operation was attempted on a closed session."""
+
+    code = 'session_closed'
+    message = 'session is closed'
+
+
+class MalformedMessageError(SmartThingsLocalError, ValueError):
+    """A protocol message could not be decoded safely."""
+
+    code = 'malformed_message'
+    message = 'malformed protocol message'
+
+
+class BlockwiseError(SessionError):
+    """A Block1 or Block2 transfer violated its bounded contract."""
+
+    code = 'blockwise'
+    message = 'blockwise transfer failed'
+
+
+class ObserveError(SessionError):
+    """A CoAP Observe relation could not be established or maintained."""
+
+    code = 'observe'
+    message = 'Observe relation failed'