fix: align protocol error semantics

crates/wip-host/tests/host.rs

@@ -235,6 +235,10 @@ impl ObjectProvider for TestProvider {
                 )
             }
             "/empty" => (Document::open("empty", None, Rc::clone(&self.calls)), 0),
+            "/invalid-object" => (
+                Document::open("wrong-name", None, Rc::clone(&self.calls)),
+                0,
+            ),
             "/broken" => (
                 Document::open("broken", Some("broken-ref"), Rc::clone(&self.calls)),
                 3,
@@ -624,9 +628,15 @@ fn immutable_interface_rejects_a_supplied_validator() {
 }
 
 #[test]
-fn invalid_results_and_backend_failures_keep_distinct_protocol_codes() {
+fn invalid_host_responses_and_uncertain_operation_failures_use_canonical_codes() {
     let (_, provider, _) = registry_and_provider();
 
+    assert_failure(
+        provider.fetch("/invalid-object").unwrap_err(),
+        CallErrorKind::Internal,
+        ProtocolErrorCode::Internal,
+    );
+
     assert_failure(
         provider
             .call_operation(request(
@@ -639,7 +649,7 @@ fn invalid_results_and_backend_failures_keep_distinct_protocol_codes() {
             ))
             .unwrap_err(),
         CallErrorKind::InvalidResult,
-        ProtocolErrorCode::InvalidResult,
+        ProtocolErrorCode::OperationOutcomeUnknown,
     );
     assert_failure(
         provider
@@ -653,6 +663,6 @@ fn invalid_results_and_backend_failures_keep_distinct_protocol_codes() {
             ))
             .unwrap_err(),
         CallErrorKind::Implementation,
-        ProtocolErrorCode::Internal,
+        ProtocolErrorCode::OperationOutcomeUnknown,
     );
 }