feat(workbench): add runtime GIS and sample integrations

app/domain/domain_errors.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+
+class DomainError(Exception):
+    """A domain rejection with a stable API error payload."""
+
+    def __init__(self, code: str, message: str, *, refs: list | None = None,
+                 recovery: str = "none", status: int = 422):
+        super().__init__(message)
+        self.code, self.message, self.status = code, message, status
+        self.refs, self.recovery = refs or [], recovery
+
+    def payload(self) -> dict:
+        return {"code": self.code, "message": self.message,
+                "retryable": self.recovery == "retry_same_request",
+                "related_refs": self.refs, "recovery_action": self.recovery,
+                "retry_after_seconds": None}
+
+
+def require(condition: bool, code: str, message: str, **kwargs) -> None:
+    if not condition:
+        raise DomainError(code, message, **kwargs)