fix(strm): 115 元数据上传幂等，避免重复上传 (#29)

上传/重试前按父目录+文件名+SHA1 探活，已有同内容副本则跳过并清脏副本；
成功后回写新 file_id；同步扫描认可 30 分钟内同路径同大小的 done 任务，
缩短「任务已完成但列表未反映」导致的再入队窗口。

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: truewhile <truewhile@users.noreply.github.com>

internal/service/cloud115/open.go

@@ -119,6 +119,60 @@ func (c *OpenClient) GetFsListFlat(ctx context.Context, cid string, offset, limi
 	return files, resp.Count, nil
 }
 
+// FindNamedContentInParent 在父目录下查找与本地内容一致的同名文件。
+// 匹配条件：文件名完全一致、大小一致，且 SHA1 为空或与 expectedSHA1 大小写不敏感相等。
+// 同时返回该目录下全部同名文件（含未匹配的脏副本），便于上传前清理。
+// 目录过大时分页扫描，最多拉取 maxListPages 页（每页 pageSize 条）。
+func (c *OpenClient) FindNamedContentInParent(ctx context.Context, parentCID, fileName, expectedSHA1 string, expectedSize int64) (matched *RemoteFile, sameName []RemoteFile, err error) {
+	fileName = strings.TrimSpace(fileName)
+	if fileName == "" {
+		return nil, nil, nil
+	}
+	const pageSize = 200
+	const maxListPages = 20 // 最多扫描 4000 项，元数据父目录通常远小于此
+	expectedSHA1 = strings.TrimSpace(expectedSHA1)
+	offset := 0
+	for page := 0; page < maxListPages; page++ {
+		files, _, listErr := c.GetFsList(ctx, parentCID, offset, pageSize)
+		if listErr != nil {
+			return nil, sameName, listErr
+		}
+		if len(files) == 0 {
+			break
+		}
+		for i := range files {
+			f := files[i]
+			if f.Category == TypeDir {
+				continue
+			}
+			// fta=0/2 表示未上传完成，不可作为已存在副本
+			if f.Fta == "0" || f.Fta == "2" {
+				continue
+			}
+			if f.FileName != fileName {
+				continue
+			}
+			sameName = append(sameName, f)
+			if matched != nil {
+				continue
+			}
+			if f.FileSize != expectedSize {
+				continue
+			}
+			remoteSha := strings.TrimSpace(f.Sha1)
+			if remoteSha == "" || remoteSha == "-" || strings.EqualFold(remoteSha, expectedSHA1) {
+				cp := f
+				matched = &cp
+			}
+		}
+		if len(files) < pageSize {
+			break
+		}
+		offset += len(files)
+	}
+	return matched, sameName, nil
+}
+
 // GetFsDetailByCid 查询文件（夹）详情。
 func (c *OpenClient) GetFsDetailByCid(ctx context.Context, fileId string) (*RemoteFileDetail, error) {
 	params := map[string]string{"file_id": fileId}

internal/service/cloud115/open_find_test.go

@@ -0,0 +1,54 @@
+package cloud115
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"testing"
+)
+
+func TestFindNamedContentInParentMatchAndSameName(t *testing.T) {
+	sha := "AABBCCDDEEFF00112233445566778899AABBCCDD"
+	mockAPI(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/open/ufile/files" {
+			t.Errorf("unexpected path %s", r.URL.Path)
+		}
+		w.Write([]byte(fmt.Sprintf(`{"state":true,"data":[
+			{"fid":"dir-1","fc":"0","fn":"sub","fs":0},
+			{"fid":"keep","fc":"1","fn":"a.nfo","fs":10,"sha1":%q,"fta":"1"},
+			{"fid":"dirty","fc":"1","fn":"a.nfo","fs":10,"sha1":"OTHER","fta":"1"},
+			{"fid":"other","fc":"1","fn":"b.nfo","fs":10,"sha1":%q,"fta":"1"},
+			{"fid":"incomplete","fc":"1","fn":"a.nfo","fs":10,"sha1":%q,"fta":"0"}
+		]}`, sha, sha, sha)))
+	})
+	c := NewOpenClient("100195125", "at1", "rt1")
+	matched, sameName, err := c.FindNamedContentInParent(context.Background(), "parent", "a.nfo", sha, 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if matched == nil || matched.FileId != "keep" {
+		t.Fatalf("matched = %+v, want keep", matched)
+	}
+	if len(sameName) != 2 { // keep + dirty；incomplete 被 fta 过滤
+		t.Fatalf("sameName len=%d, want 2 (incomplete excluded)", len(sameName))
+	}
+}
+
+func TestFindNamedContentInParentNoMatch(t *testing.T) {
+	mockAPI(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(`{"state":true,"data":[
+			{"fid":"x","fc":"1","fn":"a.nfo","fs":9,"sha1":"OTHER","fta":"1"}
+		]}`))
+	})
+	c := NewOpenClient("100195125", "at1", "rt1")
+	matched, sameName, err := c.FindNamedContentInParent(context.Background(), "parent", "a.nfo", "WANT", 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if matched != nil {
+		t.Fatalf("expected no match, got %+v", matched)
+	}
+	if len(sameName) != 1 {
+		t.Fatalf("sameName should still list name hits, got %d", len(sameName))
+	}
+}