feat(agent): render local interactive answers and fold completed process

src/features/agent/answer-ui/contract.ts

@@ -0,0 +1,63 @@
+import type { Spec } from "@json-render/core";
+import { z } from "zod";
+import { answerUiCatalog, ANSWER_UI_VERSION } from "./catalog";
+
+const key = z.string().regex(/^[a-zA-Z0-9_-]{1,80}$/);
+const element = z
+  .object({ type: z.string(), props: z.record(z.unknown()), children: z.array(key).max(48) })
+  .strict();
+const specSchema = z.object({ root: key, elements: z.record(element) }).strict();
+const payloadSchema = z
+  .object({
+    version: z.literal(ANSWER_UI_VERSION),
+    block_id: key,
+    fallback_text: z.string().min(1).max(4000),
+    spec: specSchema
+  })
+  .strict();
+
+export type AnswerUiBlock = {
+  version: typeof ANSWER_UI_VERSION;
+  block_id: string;
+  fallback_text: string;
+  spec: Spec;
+};
+export type AnswerUiPart =
+  { type: "text"; text: string } | { type: "answer-ui"; block: AnswerUiBlock };
+
+export function parseAnswerUiBlock(value: unknown): AnswerUiBlock | null {
+  const parsed = payloadSchema.safeParse(value);
+  if (!parsed.success || JSON.stringify(parsed.data).length > 100000) return null;
+  const { spec } = parsed.data;
+  const nodes = Object.keys(spec.elements);
+  if (!nodes.length || nodes.length > 48 || nodes.some((name) => !key.safeParse(name).success))
+    return null;
+  const definitions = answerUiCatalog.data.components;
+  for (const node of Object.values(spec.elements)) {
+    const definition = Object.hasOwn(definitions, node.type)
+      ? definitions[node.type as keyof typeof definitions]
+      : undefined;
+    if (!definition?.props.safeParse(node.props).success) return null;
+    if (!["Stack", "Section"].includes(node.type) && node.children.length) return null;
+    if (node.type === "Chart") {
+      const data = node.props as { x_data: unknown[]; series: Array<{ data: unknown[] }> };
+      if (data.series.some((series) => series.data.length !== data.x_data.length)) return null;
+    }
+    if (node.type === "Table") {
+      const data = node.props as { columns: unknown[]; rows: unknown[][] };
+      if (data.rows.some((row) => row.length !== data.columns.length)) return null;
+    }
+    if (node.type === "FollowUpForm") {
+      const data = node.props as { fields: Array<{ name: string }> };
+      if (new Set(data.fields.map((field) => field.name)).size !== data.fields.length) return null;
+    }
+  }
+  const visited = new Set<string>();
+  const visit = (id: string, depth: number): boolean => {
+    if (depth > 12 || visited.has(id) || !Object.hasOwn(spec.elements, id)) return false;
+    visited.add(id);
+    return spec.elements[id].children.every((child) => visit(child, depth + 1));
+  };
+  if (!visit(spec.root, 0) || visited.size !== nodes.length) return null;
+  return parsed.data;
+}