Function schemaToJsonSchema

packages/core/src/action.ts:227–258

* Convert a Standard Schema to JSON Schema for the Claude API. * Tries vendor-specific toJSONSchema first (Zod v4), then falls back * to a basic introspection of the schema shape.

(
  schema: StandardSchemaV1,
  _description?: string,
)

 * to a basic introspection of the schema shape.
 */
function schemaToJsonSchema(
  schema: StandardSchemaV1,
  _description?: string,
): ActionTool["parameters"] {
  const s = schema as any;

  // Prefer Zod's own JSON Schema output — it handles descriptions,
  // enums, coerce, and all type wrappers correctly.
  if (s["~standard"]?.jsonSchema?.input) {
    try {
      const result = s["~standard"].jsonSchema.input({
        target: "draft-07",
      }) as any;
      // Strip $schema — the Claude API validates against draft 2020-12
      // and a mismatched $schema declaration can cause rejections.
      if (result && typeof result === "object") {
        delete result.$schema;
      }
      return result as ActionTool["parameters"];
    } catch {
      // Fall through to manual converter
    }
  }

  // Fallback: manual conversion from Zod v4 internal defs
  if (s._zod?.def) {
    return zodDefToJsonSchema(s._zod.def);
  }

  // Last resort: empty object schema
  return { type: "object" as const, properties: {} };
}

/**
 * Convert a Zod v4 internal def to JSON Schema.