1 files changed, 21 insertions, 0 deletions
diff --git a/src/mcp_sd15/errors.py b/src/mcp_sd15/errors.py
new file mode 100644
index 0000000..59ba567
--- /dev/null
+++ b/src/mcp_sd15/errors.py
@@ -0,0 +1,21 @@
+"""Application error types exposed at architectural boundaries."""
+
+
+class SD15Error(Exception):
+    """Base application error."""
+
+
+class ConfigError(SD15Error):
+    """Configuration is invalid or incomplete."""
+
+
+class InvalidRequestError(SD15Error):
+    """A tool request is invalid."""
+
+
+class InvalidImageError(InvalidRequestError):
+    """An input is not a supported image."""
+
+
+class GenerationError(SD15Error):
+    """The inference backend failed."""