feat: add v0.1 runtime skeleton

src/common/errors.ts

@@ -0,0 +1,28 @@
+import type { FailureKind, JsonRecord } from "./types.js";
+
+export class AgentRunError extends Error {
+  readonly failureKind: FailureKind;
+  readonly details: JsonRecord | null;
+  readonly httpStatus: number;
+
+  constructor(failureKind: FailureKind, message: string, options: { httpStatus?: number; details?: JsonRecord } = {}) {
+    super(message);
+    this.name = "AgentRunError";
+    this.failureKind = failureKind;
+    this.httpStatus = options.httpStatus ?? 400;
+    this.details = options.details ?? null;
+  }
+}
+
+export function errorToJson(error: unknown): JsonRecord {
+  if (error instanceof AgentRunError) {
+    return {
+      name: error.name,
+      failureKind: error.failureKind,
+      message: error.message,
+      details: error.details,
+    };
+  }
+  if (error instanceof Error) return { name: error.name, message: error.message, stack: error.stack ?? null };
+  return { name: "UnknownError", message: String(error) };
+}