Frontend iframe renderer framework: 3D models, OpenAPI (#37233)

Introduces a frontend external-render framework that runs renderer
plugins inside an `iframe` (loaded via `srcdoc` to keep the CSP
`sandbox` directive working without origin-related console noise), and
migrates the 3D viewer and OpenAPI/Swagger renderers onto it. PDF and
asciicast paths are refactored to share the same `data-render-name`
mechanism.

Adds e2e coverage for 3D, PDF, asciicast and OpenAPI render paths, plus
a regression for the `RefTypeNameSubURL` double-escape on non-ASCII
branch names.

Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/repo/render.go

@@ -43,7 +43,8 @@ func RenderFile(ctx *context.Context) {
 		CurrentRefPath:  ctx.Repo.RefTypeNameSubURL(),
 		CurrentTreePath: path.Dir(ctx.Repo.TreePath),
 	}).WithRelativePath(ctx.Repo.TreePath).WithStandalonePage(markup.StandalonePageOptions{
-		CurrentWebTheme: ctx.TemplateContext.CurrentWebTheme(),
+		CurrentWebTheme:   ctx.TemplateContext.CurrentWebTheme(),
+		RenderQueryString: ctx.Req.URL.RawQuery,
 	})
 	renderer, rendererInput, err := rctx.DetectMarkupRendererByReader(blobReader)
 	if err != nil {

routers/web/repo/view_file.go

@@ -21,6 +21,7 @@ import (
 	"code.gitea.io/gitea/modules/git/attribute"
 	"code.gitea.io/gitea/modules/highlight"
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/context"
@@ -76,14 +77,17 @@ func handleFileViewRenderMarkup(ctx *context.Context, prefetchBuf []byte, utf8Re
 		return false
 	}
 
-	ctx.Data["MarkupType"] = rctx.RenderOptions.MarkupType
-
 	var err error
 	ctx.Data["EscapeStatus"], ctx.Data["FileContent"], err = markupRenderToHTML(ctx, rctx, renderer, utf8Reader)
 	if err != nil {
 		ctx.ServerError("Render", err)
 		return true
 	}
+
+	opts, ok := markup.GetExternalRendererOptions(renderer)
+	usingIframe := ok && opts.DisplayInIframe
+	ctx.Data["MarkupType"] = rctx.RenderOptions.MarkupType
+	ctx.Data["RenderAsMarkup"] = util.Iif(usingIframe, "markup-iframe", "markup-inplace")
 	return true
 }
 
@@ -235,8 +239,6 @@ func prepareFileView(ctx *context.Context, entry *git.TreeEntry) {
 	case fInfo.blobOrLfsSize >= setting.UI.MaxDisplayFileSize:
 		ctx.Data["IsFileTooLarge"] = true
 	case handleFileViewRenderMarkup(ctx, buf, contentReader):
-		// it also sets ctx.Data["FileContent"] and more
-		ctx.Data["IsMarkup"] = true
 	case handleFileViewRenderSource(ctx, attrs, fInfo, contentReader):
 		// it also sets ctx.Data["FileContent"] and more
 		ctx.Data["IsDisplayingSource"] = true

routers/web/repo/view_readme.go

@@ -195,16 +195,16 @@ func prepareToRenderReadmeFile(ctx *context.Context, subfolder string, readmeFil
 	}).WithRelativePath(readmeFullPath)
 	renderer := rctx.DetectMarkupRenderer(buf)
 	if renderer != nil {
-		ctx.Data["IsMarkup"] = true
+		ctx.Data["RenderAsMarkup"] = "markup-inplace"
 		ctx.Data["MarkupType"] = rctx.RenderOptions.MarkupType
 		ctx.Data["EscapeStatus"], ctx.Data["FileContent"], err = markupRenderToHTML(ctx, rctx, renderer, rd)
 		if err != nil {
 			log.Error("Render failed for %s in %-v: %v Falling back to rendering source", readmeFile.Name(), ctx.Repo.Repository, err)
-			delete(ctx.Data, "IsMarkup")
+			delete(ctx.Data, "RenderAsMarkup")
 		}
 	}
 
-	if ctx.Data["IsMarkup"] != true {
+	if ctx.Data["RenderAsMarkup"] == nil {
 		ctx.Data["IsPlainText"] = true
 		content, err := io.ReadAll(rd)
 		if err != nil {