Add API endpoint to reply to pull request review comments (#36683)

Adds a dedicated endpoint for replying to pull request review comments,

```
POST /repos/{owner}/{repo}/pulls/{index}/comments/{id}/replies
{ "body": "..." }
```

The reply is threaded under the same review as the parent comment.

Ref: https://gitea.com/gitea/gitea-mcp/issues/129
Fixes: https://github.com/go-gitea/gitea/issues/37419
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/v1/api.go

@@ -1369,6 +1369,7 @@ func Routes() *web.Router {
 						m.Combo("/requested_reviewers", reqToken()).
 							Delete(bind(api.PullReviewRequestOptions{}), repo.DeleteReviewRequests).
 							Post(bind(api.PullReviewRequestOptions{}), repo.CreateReviewRequests)
+						m.Post("/comments/{id}/replies", reqToken(), mustNotBeArchived, bind(api.CreatePullReviewCommentReplyOptions{}), repo.CreatePullReviewCommentReply)
 					})
 					m.Get("/{base}/*", repo.GetPullRequestByBaseHead)
 				}, mustAllowPulls, reqRepoReader(unit.TypeCode), context.ReferencesGitRepo())

routers/api/v1/repo/pull_review.go

@@ -208,6 +208,88 @@ func GetPullReviewComments(ctx *context.APIContext) {
 	ctx.JSON(http.StatusOK, apiComments)
 }
 
+// CreatePullReviewCommentReply replies to a pull request review comment.
+// The URL mirrors GitHub's endpoint, {index} is verified against the parent comment's pull request.
+func CreatePullReviewCommentReply(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/pulls/{index}/comments/{id}/replies repository repoCreatePullReviewCommentReply
+	// ---
+	// summary: Reply to a pull request review comment
+	// consumes:
+	// - application/json
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: index
+	//   in: path
+	//   description: index of the pull request
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// - name: id
+	//   in: path
+	//   description: id of the review comment to reply to
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// - name: body
+	//   in: body
+	//   required: true
+	//   schema:
+	//     "$ref": "#/definitions/CreatePullReviewCommentReplyOptions"
+	// responses:
+	//   "201":
+	//     "$ref": "#/responses/PullReviewComment"
+	//   "400":
+	//     "$ref": "#/responses/validationError"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+
+	opts := web.GetForm(ctx).(*api.CreatePullReviewCommentReplyOptions)
+
+	parent := getPullReviewCommentToResolve(ctx)
+	if parent == nil {
+		return
+	}
+	if parent.Issue.Index != ctx.PathParamInt64("index") {
+		ctx.APIErrorNotFound()
+		return
+	}
+	if parent.ReviewID == 0 {
+		ctx.APIError(http.StatusBadRequest, "comment is not a review comment")
+		return
+	}
+
+	comment, err := pull_service.CreateCodeComment(ctx,
+		ctx.Doer, ctx.Repo.GitRepo, parent.Issue,
+		parent.Line, opts.Body, parent.TreePath,
+		false, parent.ReviewID,
+		"", nil,
+	)
+	if err != nil {
+		ctx.APIErrorInternal(err)
+		return
+	}
+	if err := comment.LoadPoster(ctx); err != nil {
+		ctx.APIErrorInternal(err)
+		return
+	}
+	comment.Issue = parent.Issue
+
+	ctx.JSON(http.StatusCreated, convert.ToPullReviewComment(ctx, comment, ctx.Doer))
+}
+
 // ResolvePullReviewComment resolves a review comment in a pull request
 func ResolvePullReviewComment(ctx *context.APIContext) {
 	// swagger:operation POST /repos/{owner}/{repo}/pulls/comments/{id}/resolve repository repoResolvePullReviewComment

routers/api/v1/swagger/options.go

@@ -168,6 +168,9 @@ type swaggerParameterBodies struct {
 	// in:body
 	CreatePullReviewComment api.CreatePullReviewComment
 
+	// in:body
+	CreatePullReviewCommentReplyOptions api.CreatePullReviewCommentReplyOptions
+
 	// in:body
 	SubmitPullReviewOptions api.SubmitPullReviewOptions