Migrate to Zod 4

Single-arg z.record(z.number()) -> z.record(z.string(), z.number()) in
templates.ts (also fixes the choice_scores Record<number> inference in llm.ts),
and replace the zod-4-incompatible zod-to-json-schema with native
z.toJSONSchema in ragas.ts. Package typechecks cleanly under Zod 4.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: starfolkbot

js/ragas.ts

@@ -109,9 +109,16 @@ import OpenAI from "openai";
 import { ListContains } from "./list";
 import { EmbeddingSimilarity } from "./string";
 import { z } from "zod";
-import zodToJsonSchema from "zod-to-json-schema";
 import { makePartial, ScorerWithPartial } from "./partial";
 
+function zodToJsonSchema(schema: z.ZodType): Record<string, unknown> {
+  return z.toJSONSchema(schema, {
+    target: "draft-7",
+    io: "input",
+    unrepresentable: "any",
+  });
+}
+
 type RagasArgs = {
   input?: string;
   context?: string | string[];

js/templates.ts

@@ -13,7 +13,7 @@ import translation from "../templates/translation.yaml";
 
 export const modelGradedSpecSchema = z.object({
   prompt: z.string(),
-  choice_scores: z.record(z.number()),
+  choice_scores: z.record(z.string(), z.number()),
   model: z.string().optional(),
   use_cot: z.boolean().optional(),
   temperature: z.number().optional(),