Add in_reply_to field for threading pull review comments via API

modules/structs/pull_review.go

@@ -89,6 +89,9 @@ type CreatePullReviewComment struct {
 	OldLineNum int64 `json:"old_position"`
 	// if comment to new file line or 0
 	NewLineNum int64 `json:"new_position"`
+	// if comment is a reply to an existing review thread, the review ID (pull_request_review_id) to reply to;
+	// the new comment will be threaded under that review
+	InReplyTo int64 `json:"in_reply_to"`
 }
 
 // SubmitPullReviewOptions are options to submit a pending pull request review

routers/api/v1/repo/pull_review.go

@@ -420,6 +420,8 @@ func CreatePullReview(ctx *context.APIContext) {
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/PullReview"
+	//   "204":
+	//     description: no content (reply-only request with no review body)
 	//   "404":
 	//     "$ref": "#/responses/notFound"
 	//   "422":
@@ -436,8 +438,20 @@ func CreatePullReview(ctx *context.APIContext) {
 		return
 	}
 
-	// determine review type
-	reviewType, isWrong := preparePullReviewType(ctx, pr, opts.Event, opts.Body, len(opts.Comments) > 0)
+	// separate reply comments from pending comments
+	var pendingComments []api.CreatePullReviewComment
+	var replyComments []api.CreatePullReviewComment
+	for _, c := range opts.Comments {
+		if c.InReplyTo > 0 {
+			replyComments = append(replyComments, c)
+		} else {
+			pendingComments = append(pendingComments, c)
+		}
+	}
+
+	// determine review type (reply comments count as "having comments" for validation)
+	hasComments := len(pendingComments) > 0 || len(replyComments) > 0
+	reviewType, isWrong := preparePullReviewType(ctx, pr, opts.Event, opts.Body, hasComments)
 	if isWrong {
 		return
 	}
@@ -465,8 +479,40 @@ func CreatePullReview(ctx *context.APIContext) {
 		opts.CommitID = headCommitID
 	}
 
-	// create review comments
-	for _, c := range opts.Comments {
+	// create reply comments (posted immediately, not part of the pending review)
+	for _, c := range replyComments {
+		line := c.NewLineNum
+		if c.OldLineNum > 0 {
+			line = c.OldLineNum * -1
+		}
+
+		if _, err := pull_service.CreateCodeComment(ctx,
+			ctx.Doer,
+			ctx.Repo.GitRepo,
+			pr.Issue,
+			line,
+			c.Body,
+			c.Path,
+			false,       // not a pending review
+			c.InReplyTo, // review ID to reply to
+			opts.CommitID,
+			nil,
+		); err != nil {
+			ctx.APIErrorInternal(err)
+			return
+		}
+	}
+
+	// if there are no pending comments and no review body, skip creating a review
+	// unless the user wants to approve or request changes (which are meaningful without comments)
+	if len(pendingComments) == 0 && len(opts.Body) == 0 &&
+		reviewType != issues_model.ReviewTypeApprove && reviewType != issues_model.ReviewTypeReject {
+		ctx.Status(http.StatusNoContent)
+		return
+	}
+
+	// create pending review comments
+	for _, c := range pendingComments {
 		line := c.NewLineNum
 		if c.OldLineNum > 0 {
 			line = c.OldLineNum * -1

tests/integration/api_pull_review_test.go

@@ -437,6 +437,99 @@ func TestAPIPullReviewCommentResolveEndpoints(t *testing.T) {
 	MakeRequest(t, req, http.StatusForbidden)
 }
 
+func TestAPIPullReviewCommentReply(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	ctx := t.Context()
+	pullIssue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{ID: 3})
+	require.NoError(t, pullIssue.LoadAttributes(ctx))
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: pullIssue.RepoID})
+
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	require.NoError(t, pullIssue.LoadPullRequest(ctx))
+	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
+	require.NoError(t, err)
+	defer gitRepo.Close()
+
+	latestCommitID, err := gitRepo.GetRefCommitID(pullIssue.PullRequest.GetGitHeadRefName())
+	require.NoError(t, err)
+
+	// Create a code comment to reply to (this creates a review)
+	comment, err := pull_service.CreateCodeComment(ctx, doer, gitRepo, pullIssue, 1, "original comment", "README.md", false, 0, latestCommitID, nil)
+	require.NoError(t, err)
+	require.NotNil(t, comment)
+	originalReviewID := comment.ReviewID
+
+	session := loginUser(t, doer.Name)
+	token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteRepository)
+
+	// Test: reply to an existing review comment using in_reply_to
+	req := NewRequestWithJSON(t, http.MethodPost, fmt.Sprintf("/api/v1/repos/%s/%s/pulls/%d/reviews", repo.OwnerName, repo.Name, pullIssue.Index), &api.CreatePullReviewOptions{
+		Event: "COMMENT",
+		Comments: []api.CreatePullReviewComment{
+			{
+				Path:       "README.md",
+				Body:       "reply to original comment",
+				NewLineNum: 1,
+				InReplyTo:  originalReviewID,
+			},
+		},
+	}).AddTokenAuth(token)
+	// Reply-only reviews return 204 No Content (no new review is created)
+	MakeRequest(t, req, http.StatusNoContent)
+
+	// Verify the reply comment was created under the original review
+	reviews, err := issues_model.FindReviews(ctx, issues_model.FindReviewOptions{
+		IssueID:    pullIssue.ID,
+		ReviewerID: doer.ID,
+	})
+	require.NoError(t, err)
+
+	// Find the original review and check it has the reply
+	var foundReply bool
+	for _, review := range reviews {
+		if review.ID == originalReviewID {
+			require.NoError(t, review.LoadCodeComments(ctx))
+			for _, commentsPerLine := range review.CodeComments {
+				for _, comments := range commentsPerLine {
+					for _, c := range comments {
+						if c.Content == "reply to original comment" {
+							foundReply = true
+						}
+					}
+				}
+			}
+		}
+	}
+	assert.True(t, foundReply, "reply comment should be threaded under the original review")
+
+	// Test: mix of reply and non-reply comments creates a review
+	req = NewRequestWithJSON(t, http.MethodPost, fmt.Sprintf("/api/v1/repos/%s/%s/pulls/%d/reviews", repo.OwnerName, repo.Name, pullIssue.Index), &api.CreatePullReviewOptions{
+		Body:  "mixed review",
+		Event: "COMMENT",
+		Comments: []api.CreatePullReviewComment{
+			{
+				Path:       "README.md",
+				Body:       "another reply",
+				NewLineNum: 1,
+				InReplyTo:  originalReviewID,
+			},
+			{
+				Path:       "README.md",
+				Body:       "new standalone comment",
+				NewLineNum: 1,
+			},
+		},
+	}).AddTokenAuth(token)
+	resp := MakeRequest(t, req, http.StatusOK)
+	var review api.PullReview
+	DecodeJSON(t, resp, &review)
+	assert.EqualValues(t, "COMMENT", review.State)
+	assert.Equal(t, "mixed review", review.Body)
+	// Only the non-reply comment should be in the new review
+	assert.Equal(t, 1, review.CodeCommentsCount)
+}
+
 func TestAPIPullReviewStayDismissed(t *testing.T) {
 	// This test against issue https://github.com/go-gitea/gitea/issues/28542
 	// where old reviews surface after a review request got dismissed.