From 166f106b7fde7ec8bfe31d2c3d44ab4e323f45b5 Mon Sep 17 00:00:00 2001
From: ChenRussell <792608290@qq.com>
Date: Fri, 13 Mar 2026 18:26:20 +0800
Subject: [PATCH] fix: ensure builtin engine handles simple formats correctly

Builtin engine was incorrectly falling back to simple engine for md/txt/csv files. Added explicit builtin engine check in selection logic.

Fixes #755
---
 internal/application/service/knowledge.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/internal/application/service/knowledge.go b/internal/application/service/knowledge.go
index 36664879..868efd5a 100644
--- a/internal/application/service/knowledge.go
+++ b/internal/application/service/knowledge.go
@@ -7449,7 +7449,11 @@ func (s *knowledgeService) resolveDocReader(engine, fileType string, isURL bool,
 		return docparser.NewMinerUReader(overrides)
 	case "mineru_cloud":
 		return docparser.NewMinerUCloudReader(overrides)
+	case "builtin":
+		// 明确指定使用 builtin 引擎（docreader），不使用 simple format 兜底
+		return s.documentReader
 	default:
+		// 未指定引擎时的兜底逻辑：simple format 使用 Go 原生处理，其他使用 docreader
 		if !isURL && docparser.IsSimpleFormat(fileType) {
 			return &docparser.SimpleFormatReader{}
 		}