fix(rag): detect top-level JSON arrays in auto format detection

.changeset/curly-donkeys-detect.md

@@ -0,0 +1,5 @@
+---
+"@voltagent/rag": patch
+---
+
+fix(rag): detect top-level JSON arrays in `detectFormat` so the `auto` chunking strategy routes them to the JSON chunker instead of the recursive one

packages/rag/src/__tests__/format-detector.spec.ts

@@ -0,0 +1,27 @@
+import { describe, expect, it } from "vitest";
+import { chunkByStrategy } from "../document/transformers";
+import { detectFormat } from "../utils/format-detector";
+
+describe("detectFormat", () => {
+  it("detects a top-level JSON array", () => {
+    expect(detectFormat('[{"id":1},{"id":2}]')).toBe("json");
+  });
+
+  it("detects a top-level JSON object", () => {
+    expect(detectFormat('{"id":1}')).toBe("json");
+  });
+
+  it("falls through when the brackets do not parse as JSON", () => {
+    expect(detectFormat("[unclosed]")).toBe("text");
+    expect(detectFormat("{not json")).toBe("text");
+  });
+});
+
+describe("chunkByStrategy auto", () => {
+  it("routes a top-level JSON array to the JSON chunker", () => {
+    const chunks = chunkByStrategy("auto", '[{"name":"alice"},{"name":"bob"}]');
+    expect(chunks.length).toBeGreaterThan(0);
+    expect(chunks[0]?.metadata?.fields).toBe(2);
+    expect(chunks.map((chunk) => chunk.content).join("\n")).toContain("0.name: alice");
+  });
+});

packages/rag/src/utils/format-detector.ts

@@ -19,7 +19,10 @@ export function detectFormat(input: string): DetectedFormat {
   if (!text) return "text";
 
   // JSON: quick check + parse
-  if ((text.startsWith("{") || text.startsWith("[")) && text.endsWith("}")) {
+  if (
+    (text.startsWith("{") && text.endsWith("}")) ||
+    (text.startsWith("[") && text.endsWith("]"))
+  ) {
     try {
       JSON.parse(text);
       return "json";