Add structured MCP tool errors

crates/crank-community-mcp/tests/unit.rs

@@ -1,2 +1,4 @@
 #[path = "unit/manifest.rs"]
 mod manifest;
+#[path = "unit/tool_error.rs"]
+mod tool_error;

crates/crank-community-mcp/tests/unit/tool_error.rs

@@ -0,0 +1,45 @@
+use crank_adapter_rest::RestAdapterError;
+use crank_community_mcp::tool_error::tool_error_contract_from_runtime;
+use crank_runtime::RuntimeError;
+use serde_json::json;
+
+#[test]
+fn maps_upstream_429_to_recoverable_structured_tool_error() {
+    let contract = tool_error_contract_from_runtime(
+        &RuntimeError::RestAdapter(RestAdapterError::UnexpectedStatus {
+            status: 429,
+            body: json!({
+                "error": "rate limit exceeded",
+                "internal_trace": "do not leak"
+            }),
+        }),
+        "req-429",
+    );
+
+    assert_eq!(contract.error_code, "upstream_rate_limited");
+    assert!(contract.recoverable);
+    assert_eq!(contract.upstream_status, Some(429));
+    assert_eq!(contract.request_id, "req-429");
+    assert_eq!(contract.suggested_action, Some("Повторите запрос позже."));
+    assert!(!contract.message.contains("internal_trace"));
+}
+
+#[test]
+fn maps_mapping_error_to_non_recoverable_structured_tool_error() {
+    let contract = tool_error_contract_from_runtime(
+        &RuntimeError::InvalidPreparedRequest {
+            field: "query.base".to_owned(),
+            reason: "expected string".to_owned(),
+        },
+        "req-map",
+    );
+
+    assert_eq!(contract.error_code, "runtime_error");
+    assert!(!contract.recoverable);
+    assert_eq!(contract.upstream_status, None);
+    assert_eq!(contract.request_id, "req-map");
+    assert_eq!(
+        contract.suggested_action,
+        Some("Проверьте параметры вызова инструмента.")
+    );
+}