fix(api): add index tiebreaker to commit status ordering (#39508)

Commit status list orders only by `created_unix`/`updated_unix`, which
have 1-second resolution while CI often posts many statuses per second.
With LIMIT/OFFSET paging, databases (e.g. PostgreSQL using a Sort plan)
may order tied rows differently per page, so `GET
/repos/{owner}/{repo}/commits/{ref}/statuses` returns some statuses
twice and never returns others.

This became visible after https://github.com/go-gitea/gitea/pull/36521
made requests without `page` paginated. Clients like Renovate that page
until `X-Total-Count` can miss a context's newest status and see a stale
`pending`, blocking automerge.

Fix: add `index` (unique per commit) as a tiebreaker to the
timestamp-based orders.

Co-authored-by: silverwind <me@silverwind.io>

models/git/commit_status.go

@@ -311,17 +311,17 @@ func (opts *CommitStatusOptions) ToConds() builder.Cond {
 func (opts *CommitStatusOptions) ToOrders() string {
 	switch opts.SortType {
 	case "oldest":
-		return "created_unix ASC"
+		return "created_unix ASC, `index` ASC"
 	case "recentupdate":
-		return "updated_unix DESC"
+		return "updated_unix DESC, `index` DESC"
 	case "leastupdate":
-		return "updated_unix ASC"
+		return "updated_unix ASC, `index` ASC"
 	case "leastindex":
 		return "`index` DESC"
 	case "highestindex":
 		return "`index` ASC"
 	default:
-		return "created_unix DESC"
+		return "created_unix DESC, `index` DESC" // timestamps have 1s resolution, `index` keeps paging stable
 	}
 }
 

models/git/commit_status_test.go

@@ -32,28 +32,15 @@ func TestGetCommitStatuses(t *testing.T) {
 	})
 	assert.NoError(t, err)
 	assert.Equal(t, 5, int(maxResults))
-	assert.Len(t, statuses, 5)
-
-	assert.Equal(t, "ci/awesomeness", statuses[0].Context)
-	assert.Equal(t, commitstatus.CommitStatusPending, statuses[0].State)
+	var indexes []int64
+	for _, status := range statuses {
+		indexes = append(indexes, status.Index)
+	}
+	assert.Equal(t, []int64{5, 4, 3, 2, 1}, indexes)
+	assert.Equal(t, "deploy/awesomeness", statuses[0].Context)
+	assert.Equal(t, commitstatus.CommitStatusError, statuses[0].State)
 	assert.Equal(t, "https://try.gitea.io/api/v1/repos/user2/repo1/statuses/1234123412341234123412341234123412341234", statuses[0].APIURL(t.Context()))
 
-	assert.Equal(t, "cov/awesomeness", statuses[1].Context)
-	assert.Equal(t, commitstatus.CommitStatusWarning, statuses[1].State)
-	assert.Equal(t, "https://try.gitea.io/api/v1/repos/user2/repo1/statuses/1234123412341234123412341234123412341234", statuses[1].APIURL(t.Context()))
-
-	assert.Equal(t, "cov/awesomeness", statuses[2].Context)
-	assert.Equal(t, commitstatus.CommitStatusSuccess, statuses[2].State)
-	assert.Equal(t, "https://try.gitea.io/api/v1/repos/user2/repo1/statuses/1234123412341234123412341234123412341234", statuses[2].APIURL(t.Context()))
-
-	assert.Equal(t, "ci/awesomeness", statuses[3].Context)
-	assert.Equal(t, commitstatus.CommitStatusFailure, statuses[3].State)
-	assert.Equal(t, "https://try.gitea.io/api/v1/repos/user2/repo1/statuses/1234123412341234123412341234123412341234", statuses[3].APIURL(t.Context()))
-
-	assert.Equal(t, "deploy/awesomeness", statuses[4].Context)
-	assert.Equal(t, commitstatus.CommitStatusError, statuses[4].State)
-	assert.Equal(t, "https://try.gitea.io/api/v1/repos/user2/repo1/statuses/1234123412341234123412341234123412341234", statuses[4].APIURL(t.Context()))
-
 	statuses, maxResults, err = db.FindAndCount[git_model.CommitStatus](t.Context(), &git_model.CommitStatusOptions{
 		ListOptions: db.ListOptions{Page: 2, PageSize: 50},
 		RepoID:      repo1.ID,