feat(backend): add video scene preview generation and endpoint

- Register a new route `GET /d/{boxID}/scene/{fileID}` to serve video scene previews.
- Implement the `VideoScenesPreview` handler to serve existing previews or generate them on-demand.
- Add helper functions to analyze video frames (e.g., luma calculation to filter out dark frames) and render the final scene thumbnail.
- Update the `fileView` struct to include scene URL and status fields.

backend/libs/handlers/app.go

@@ -132,8 +132,12 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("POST /d/{boxID}/f/{fileID}/react", a.ReactToFile)
 	mux.HandleFunc("GET /d/{boxID}/f/{fileID}", a.DownloadFile)
 	mux.HandleFunc("GET /d/{boxID}/f/{fileID}/download", a.DownloadFileContent)
+	mux.HandleFunc("GET /d/{boxID}/f/{fileID}/og-image.jpg", a.FileOGImage)
 	mux.HandleFunc("GET /d/{boxID}/thumb/{fileID}", a.Thumbnail)
+	mux.HandleFunc("GET /d/{boxID}/scene/{fileID}", a.VideoScenesPreview)
 	mux.HandleFunc("GET /d/{boxID}/og-image.jpg", a.BoxOGImage)
+	mux.HandleFunc("GET /robots.txt", a.RobotsTxt)
+	mux.HandleFunc("GET /sitemap.xml", a.SitemapXML)
 	mux.HandleFunc("GET /health", a.Health)
 	mux.HandleFunc("GET /healthz", notFound)
 	mux.HandleFunc("GET /api/v1/health", notFound)

backend/libs/handlers/download.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"warpbox.dev/backend/libs/helpers"
+	"warpbox.dev/backend/libs/jobs"
 	"warpbox.dev/backend/libs/services"
 	"warpbox.dev/backend/libs/web"
 )
@@ -40,12 +41,15 @@ type fileView struct {
 	ID           string
 	Name         string
 	Size         string
+	SizeBytes    int64
 	ContentType  string
 	PreviewKind  string
 	URL          string
 	DownloadURL  string
 	ThumbnailURL string
+	SceneURL     string
 	HasThumbnail bool
+	HasScene     bool
 	IconURL      string
 	IconRetroURL string
 	ReactURL     string
@@ -103,14 +107,17 @@ func (a *App) DownloadPage(w http.ResponseWriter, r *http.Request) {
 	}
 	locked := a.uploadService.IsProtected(box) && !a.isBoxUnlocked(r, box)
 	if isSocialPreviewBot(r) && !locked && len(box.Files) == 1 {
-		if box.Files[0].Processing {
+		file := box.Files[0]
+		if file.Processing {
 			http.Error(w, "file is still processing", http.StatusAccepted)
 			return
 		}
-		a.serveFileContent(w, r, box, box.Files[0], false)
-		a.logger.Info("single-file box served inline for social preview", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2008, "box_id", box.ID, "file_id", box.Files[0].ID)...)
+		if shouldServeRawSocialMedia(file) {
+			a.serveFileContent(w, r, box, file, false)
+			a.logger.Info("single-file media served inline for social preview", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2008, "box_id", box.ID, "file_id", file.ID)...)
 			return
 		}
+	}
 	visitorID := a.reactionVisitorID(w, r)
 	reactionsByFile, reactedByFile, err := a.reactionService.SummaryForBox(box.ID, visitorID)
 	if err != nil {
@@ -131,15 +138,37 @@ func (a *App) DownloadPage(w http.ResponseWriter, r *http.Request) {
 	expiresLabel := boxExpiryLabel(box.ExpiresAt, "Jan 2, 2006 15:04 MST")
 	title := "Shared files on Warpbox"
 	description := fmt.Sprintf("%d file%s shared via Warpbox · expires %s", len(box.Files), plural(len(box.Files)), expiresLabel)
+	ogImage := absoluteURL(r, fmt.Sprintf("/d/%s/og-image.jpg", box.ID))
+	imageAlt := fmt.Sprintf("%d shared file%s on Warp Box", len(box.Files), plural(len(box.Files)))
+	imageType := "image/jpeg"
+	if !locked && len(box.Files) == 1 && !box.Files[0].Processing {
+		file := box.Files[0]
+		view := a.fileView(box, file)
+		fileSize := helpers.FormatBytes(file.Size)
+		title = file.Name
+		description = fileShareDescription(fileSize, file.ContentType, box.ExpiresAt)
+		ogImage = socialImageURL(r, box, file, view)
+		imageAlt = fmt.Sprintf("Download card for %s", file.Name)
+		imageType = socialImageType(file)
+	}
 	if locked && box.Obfuscate {
 		title = "Protected Warpbox link"
 		description = "This shared box is password protected."
 	}
 
+	pageURL := absoluteURL(r, fmt.Sprintf("/d/%s", box.ID))
+
+	// All user uploads are private/temporary — noindex by default.
+	robots := web.RobotsNone
+
 	a.renderPage(w, r, http.StatusOK, "download.html", web.PageData{
 		Title:        title,
 		Description:  description,
-		ImageURL:    absoluteURL(r, fmt.Sprintf("/d/%s/og-image.jpg", box.ID)),
+		CanonicalURL: pageURL,
+		Robots:       robots,
+		ImageURL:     ogImage,
+		ImageAlt:     imageAlt,
+		ImageType:    imageType,
 		Data: downloadPageData{
 			Box:           boxView{ID: box.ID},
 			Files:         files,
@@ -162,6 +191,43 @@ func plural(n int) string {
 	return "s"
 }
 
+func shouldServeRawSocialMedia(file services.File) bool {
+	return file.PreviewKind == "image" || file.PreviewKind == "video"
+}
+
+func fileShareDescription(size, contentType string, expiresAt time.Time) string {
+	if strings.TrimSpace(contentType) == "" {
+		contentType = "file"
+	}
+	return fmt.Sprintf("%s · %s · click to preview or download · expires %s", size, contentType, boxExpiryLabel(expiresAt, "Jan 2, 2006"))
+}
+
+func socialImageURL(r *http.Request, box services.Box, file services.File, view fileView) string {
+	if file.PreviewKind == "image" {
+		return absoluteURL(r, view.DownloadURL+"?inline=1")
+	}
+	if file.PreviewKind == "video" && view.HasThumbnail {
+		return absoluteURL(r, view.ThumbnailURL)
+	}
+	return absoluteURL(r, fmt.Sprintf("/d/%s/f/%s/og-image.jpg", box.ID, file.ID))
+}
+
+func socialImageType(file services.File) string {
+	if file.PreviewKind == "image" {
+		return file.ContentType
+	}
+	return "image/jpeg"
+}
+
+func socialOGType(file services.File) string {
+	switch file.PreviewKind {
+	case "video":
+		return "video.other"
+	default:
+		return "website"
+	}
+}
+
 func (a *App) DownloadFile(w http.ResponseWriter, r *http.Request) {
 	box, file, ok := a.loadFileForRequest(w, r)
 	if !ok {
@@ -174,24 +240,45 @@ func (a *App) DownloadFile(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, "file is still processing", http.StatusAccepted)
 			return
 		}
+		if shouldServeRawSocialMedia(file) {
 			a.serveFileContent(w, r, box, file, false)
-		a.logger.Info("file served inline for social preview", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2009, "box_id", box.ID, "file_id", file.ID)...)
+			a.logger.Info("media file served inline for social preview", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2009, "box_id", box.ID, "file_id", file.ID)...)
 			return
 		}
+	}
 	view := a.fileView(box, file)
+	fileSize := helpers.FormatBytes(file.Size)
 	title := file.Name
-	description := fmt.Sprintf("%s shared via Warpbox", helpers.FormatBytes(file.Size))
-	imageURL := absoluteURL(r, view.ThumbnailURL)
+	description := fileShareDescription(fileSize, file.ContentType, box.ExpiresAt)
+	imageURL := socialImageURL(r, box, file, view)
+	imageAlt := fmt.Sprintf("Download card for %s", file.Name)
+	ogType := socialOGType(file)
+	mediaURL := ""
+	if file.PreviewKind == "video" {
+		mediaURL = absoluteURL(r, view.DownloadURL+"?inline=1")
+	}
 	if locked && box.Obfuscate {
 		title = "Protected Warpbox file"
 		description = "This shared file is password protected."
 		imageURL = absoluteURL(r, "/static/img/file-placeholder.webp")
+		imageAlt = "Password protected file on Warp Box"
+		ogType = "website"
+		mediaURL = ""
 	}
 
+	pageURL := absoluteURL(r, fmt.Sprintf("/d/%s/f/%s", box.ID, file.ID))
+
 	a.renderPage(w, r, http.StatusOK, "preview.html", web.PageData{
 		Title:        title,
 		Description:  description,
+		CanonicalURL: pageURL,
+		Robots:       web.RobotsNone,
+		OGType:       ogType,
 		ImageURL:     imageURL,
+		ImageAlt:     imageAlt,
+		ImageType:    socialImageType(file),
+		MediaURL:     mediaURL,
+		MediaType:    file.ContentType,
 		Data: previewPageData{
 			Box:         boxView{ID: box.ID},
 			File:        view,
@@ -203,6 +290,7 @@ func (a *App) DownloadFile(w http.ResponseWriter, r *http.Request) {
 }
 
 func (a *App) DownloadFileContent(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("X-Robots-Tag", "noindex, nofollow, noarchive")
 	box, file, ok := a.loadFileForRequest(w, r)
 	if !ok {
 		return
@@ -222,6 +310,7 @@ func (a *App) DownloadFileContent(w http.ResponseWriter, r *http.Request) {
 }
 
 func (a *App) Thumbnail(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("X-Robots-Tag", "noindex, nofollow, noarchive")
 	box, file, ok := a.loadFileForRequest(w, r)
 	if !ok {
 		return
@@ -233,6 +322,17 @@ func (a *App) Thumbnail(w http.ResponseWriter, r *http.Request) {
 
 	object, err := a.uploadService.OpenThumbnailObject(r.Context(), box, file)
 	if err != nil {
+		if thumbnail := a.generateMissingThumbnailForRequest(r, box, file); thumbnail != "" {
+			file.Thumbnail = thumbnail
+			object, err = a.uploadService.OpenThumbnailObject(r.Context(), box, file)
+			if err == nil {
+				defer object.Body.Close()
+				w.Header().Set("Content-Type", "image/jpeg")
+				w.Header().Set("Cache-Control", "public, max-age=604800, immutable")
+				http.ServeContent(w, r, file.ID+"-thumbnail.jpg", object.ModTime, readSeekCloser(object.Body))
+				return
+			}
+		}
 		// The thumbnail isn't generated yet (background job pending). Serve the
 		// placeholder but mark it non-cacheable, otherwise the browser would
 		// keep showing the placeholder until a hard refresh once the real
@@ -247,6 +347,91 @@ func (a *App) Thumbnail(w http.ResponseWriter, r *http.Request) {
 	http.ServeContent(w, r, file.ID+"-thumbnail.jpg", object.ModTime, readSeekCloser(object.Body))
 }
 
+func (a *App) VideoScenesPreview(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("X-Robots-Tag", "noindex, nofollow, noarchive")
+	box, file, ok := a.loadFileForRequest(w, r)
+	if !ok {
+		return
+	}
+	if !jobs.NeedsVideoScenes(file) {
+		http.NotFound(w, r)
+		return
+	}
+	if a.uploadService.IsProtected(box) && box.Obfuscate && !a.isBoxUnlocked(r, box) {
+		a.servePlaceholderThumbnail(w, r)
+		return
+	}
+
+	object, err := a.uploadService.OpenSceneThumbnailObject(r.Context(), box, file)
+	if err != nil {
+		if scene := a.generateMissingVideoScenesForRequest(r, box, file); scene != "" {
+			file.SceneThumbnail = scene
+			object, err = a.uploadService.OpenSceneThumbnailObject(r.Context(), box, file)
+			if err == nil {
+				defer object.Body.Close()
+				w.Header().Set("Content-Type", "image/jpeg")
+				w.Header().Set("Cache-Control", "public, max-age=604800, immutable")
+				http.ServeContent(w, r, file.ID+"-scenes.jpg", object.ModTime, readSeekCloser(object.Body))
+				return
+			}
+		}
+		a.servePlaceholderThumbnail(w, r)
+		return
+	}
+	defer object.Body.Close()
+	w.Header().Set("Content-Type", "image/jpeg")
+	w.Header().Set("Cache-Control", "public, max-age=604800, immutable")
+	http.ServeContent(w, r, file.ID+"-scenes.jpg", object.ModTime, readSeekCloser(object.Body))
+}
+
+func (a *App) generateMissingThumbnailForRequest(r *http.Request, box services.Box, file services.File) string {
+	if file.Thumbnail != "" || !jobs.NeedsThumbnail(file) {
+		return ""
+	}
+	thumbnail, err := jobs.GenerateThumbnailForFile(a.uploadService, box, file)
+	if err != nil || thumbnail == "" {
+		if err != nil {
+			a.logger.Warn("on-demand thumbnail generation failed", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4102, "box_id", box.ID, "file_id", file.ID, "error", err.Error())...)
+		}
+		return ""
+	}
+	for i := range box.Files {
+		if box.Files[i].ID == file.ID {
+			box.Files[i].Thumbnail = thumbnail
+			break
+		}
+	}
+	if err := a.uploadService.SaveBox(box); err != nil {
+		a.logger.Warn("on-demand thumbnail metadata save failed", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4103, "box_id", box.ID, "file_id", file.ID, "error", err.Error())...)
+		return ""
+	}
+	return thumbnail
+}
+
+func (a *App) generateMissingVideoScenesForRequest(r *http.Request, box services.Box, file services.File) string {
+	if file.SceneThumbnail != "" || !jobs.NeedsVideoScenes(file) {
+		return ""
+	}
+	scene, err := jobs.GenerateVideoScenesForFile(a.uploadService, box, file)
+	if err != nil || scene == "" {
+		if err != nil {
+			a.logger.Warn("on-demand video scenes preview generation failed", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4105, "box_id", box.ID, "file_id", file.ID, "error", err.Error())...)
+		}
+		return ""
+	}
+	for i := range box.Files {
+		if box.Files[i].ID == file.ID {
+			box.Files[i].SceneThumbnail = scene
+			break
+		}
+	}
+	if err := a.uploadService.SaveBox(box); err != nil {
+		a.logger.Warn("on-demand video scenes preview metadata save failed", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4106, "box_id", box.ID, "file_id", file.ID, "error", err.Error())...)
+		return ""
+	}
+	return scene
+}
+
 // servePlaceholderThumbnail serves the fallback image with no-store so the
 // browser re-requests on the next load and picks up the real thumbnail as soon
 // as it has been generated.
@@ -342,6 +527,7 @@ func readSeekCloser(source io.ReadCloser) io.ReadSeeker {
 }
 
 func (a *App) DownloadZip(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("X-Robots-Tag", "noindex, nofollow, noarchive")
 	box, err := a.uploadService.GetBox(r.PathValue("boxID"))
 	if err != nil {
 		a.logger.Warn("zip request missing box", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4044, "box_id", r.PathValue("boxID"))...)
@@ -384,12 +570,15 @@ func (a *App) fileViewWithReactions(box services.Box, file services.File, reacti
 		ID:           file.ID,
 		Name:         file.Name,
 		Size:         helpers.FormatBytes(file.Size),
+		SizeBytes:    file.Size,
 		ContentType:  file.ContentType,
 		PreviewKind:  file.PreviewKind,
 		URL:          fmt.Sprintf("/d/%s/f/%s", box.ID, file.ID),
 		DownloadURL:  fmt.Sprintf("/d/%s/f/%s/download", box.ID, file.ID),
 		ThumbnailURL: fmt.Sprintf("/d/%s/thumb/%s", box.ID, file.ID),
-		HasThumbnail: file.Thumbnail != "",
+		SceneURL:     fmt.Sprintf("/d/%s/scene/%s", box.ID, file.ID),
+		HasThumbnail: file.Thumbnail != "" || jobs.NeedsThumbnail(file),
+		HasScene:     file.SceneThumbnail != "" || jobs.NeedsVideoScenes(file),
 		IconURL:      fileIconURL("standard", icon.Standard),
 		IconRetroURL: fileIconURL("retro", icon.Retro),
 		ReactURL:     fmt.Sprintf("/d/%s/f/%s/react", box.ID, file.ID),

backend/libs/handlers/meta.go

@@ -0,0 +1,59 @@
+package handlers
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+)
+
+// RobotsTxt serves /robots.txt dynamically so the Sitemap URL reflects the
+// configured base URL rather than a hard-coded placeholder.
+func (a *App) RobotsTxt(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.Header().Set("Cache-Control", "public, max-age=86400")
+	fmt.Fprintf(w, `User-agent: *
+Allow: /
+
+# Private routes — do not crawl
+Disallow: /admin/
+Disallow: /api/
+Disallow: /app/
+Disallow: /account/
+Disallow: /d/*/f/*/download
+Disallow: /d/*/zip
+Disallow: /d/*/thumb/
+Disallow: /d/*/scene/
+Disallow: /d/*/og-image.jpg
+Disallow: /d/*/unlock
+Disallow: /d/*/manage/
+
+Sitemap: %s/sitemap.xml
+`, strings.TrimRight(siteBaseURL(r, a.cfg.BaseURL), "/"))
+}
+
+// SitemapXML serves a minimal /sitemap.xml containing only the public,
+// indexable homepage. Box/file pages are noindex and deliberately excluded.
+func (a *App) SitemapXML(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.Header().Set("Cache-Control", "public, max-age=3600")
+	baseURL := strings.TrimRight(siteBaseURL(r, a.cfg.BaseURL), "/")
+	lastMod := time.Now().UTC().Format("2006-01-02")
+	fmt.Fprintf(w, `<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+  <url>
+    <loc>%s/</loc>
+    <lastmod>%s</lastmod>
+    <changefreq>weekly</changefreq>
+    <priority>1.0</priority>
+  </url>
+</urlset>
+`, baseURL, lastMod)
+}
+
+func siteBaseURL(r *http.Request, configured string) string {
+	if configured != "" {
+		return configured
+	}
+	return absoluteURL(r, "/")
+}

backend/libs/handlers/ogimage.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"bytes"
+	"fmt"
 	"image"
 	"image/color"
 	"image/draw"
@@ -11,10 +12,18 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/basicfont"
+	"golang.org/x/image/font/opentype"
+	"golang.org/x/image/math/fixed"
 	xdraw "golang.org/x/image/draw"
 	_ "golang.org/x/image/webp"
+
+	"warpbox.dev/backend/libs/helpers"
+	"warpbox.dev/backend/libs/services"
 )
 
 // Open Graph image dimensions recommended for large summary cards
@@ -74,6 +83,22 @@ func (a *App) BoxOGImage(w http.ResponseWriter, r *http.Request) {
 	a.serveOGImage(w, r, renderCollage(thumbs))
 }
 
+// FileOGImage renders a branded card for files that should not be served as raw
+// media to social preview bots: text, Markdown, HTML, PDF, audio, archives, etc.
+func (a *App) FileOGImage(w http.ResponseWriter, r *http.Request) {
+	box, file, ok := a.loadFileForRequest(w, r)
+	if !ok {
+		return
+	}
+	if a.uploadService.IsProtected(box) && box.Obfuscate && !a.isBoxUnlocked(r, box) {
+		a.serveOGImage(w, r, a.ogPlaceholder())
+		return
+	}
+
+	icon := a.ogFileIcon(file)
+	a.serveOGImage(w, r, a.renderFileCard(file, icon))
+}
+
 func (a *App) serveOGImage(w http.ResponseWriter, r *http.Request, img image.Image) {
 	var buf bytes.Buffer
 	if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: 85}); err != nil {
@@ -115,6 +140,158 @@ func (a *App) ogPlaceholder() image.Image {
 	return canvas
 }
 
+func (a *App) ogFileIcon(file services.File) image.Image {
+	if a.fileIcons == nil {
+		return nil
+	}
+	icon := a.fileIcons.lookup(file.Name, file.ContentType)
+	if icon.Retro == "" {
+		return nil
+	}
+	path := filepath.Join(a.cfg.StaticDir, "file-icons", "retro", icon.Retro)
+	f, err := os.Open(path)
+	if err != nil {
+		return nil
+	}
+	defer f.Close()
+	img, _, err := image.Decode(f)
+	if err != nil {
+		return nil
+	}
+	return img
+}
+
+func (a *App) renderFileCard(file services.File, icon image.Image) image.Image {
+	canvas := image.NewRGBA(image.Rect(0, 0, ogImageWidth, ogImageHeight))
+	draw.Draw(canvas, canvas.Bounds(), &image.Uniform{ogBackground}, image.Point{}, draw.Src)
+
+	panel := image.Rect(70, 72, ogImageWidth-70, ogImageHeight-72)
+	draw.Draw(canvas, panel, &image.Uniform{color.RGBA{R: 0x17, G: 0x14, B: 0x2d, A: 0xff}}, image.Point{}, draw.Src)
+	draw.Draw(canvas, image.Rect(panel.Min.X, panel.Min.Y, panel.Max.X, panel.Min.Y+6), &image.Uniform{color.RGBA{R: 0xa7, G: 0x8b, B: 0xfa, A: 0xff}}, image.Point{}, draw.Src)
+
+	titleFace := a.ogFont(44, true)
+	bodyFace := a.ogFont(28, false)
+	metaFace := a.ogFont(24, false)
+	buttonFace := a.ogFont(26, true)
+
+	if icon != nil {
+		xdraw.NearestNeighbor.Scale(canvas, image.Rect(110, 142, 230, 262), icon, icon.Bounds(), xdraw.Over, nil)
+	} else {
+		draw.Draw(canvas, image.Rect(110, 142, 230, 262), &image.Uniform{color.RGBA{R: 0x21, G: 0x1b, B: 0x3e, A: 0xff}}, image.Point{}, draw.Src)
+	}
+
+	titleLines := wrapOGText(file.Name, titleFace, 850)
+	if len(titleLines) > 2 {
+		titleLines = titleLines[:2]
+		titleLines[1] = trimOGText(titleLines[1], titleFace, 850)
+	}
+	y := 156
+	for _, line := range titleLines {
+		drawOGText(canvas, titleFace, line, 265, y, color.RGBA{R: 0xf5, G: 0xf3, B: 0xff, A: 0xff})
+		y += 52
+	}
+
+	size := helpers.FormatBytes(file.Size)
+	typeLabel := strings.TrimSpace(file.ContentType)
+	if typeLabel == "" {
+		typeLabel = "application/octet-stream"
+	}
+	drawOGText(canvas, bodyFace, fmt.Sprintf("%s · %s", size, typeLabel), 265, y+12, color.RGBA{R: 0xaa, G: 0xa4, B: 0xd6, A: 0xff})
+
+	info := fileCardInfo(file)
+	for i, line := range wrapOGText(info, metaFace, 900) {
+		if i >= 2 {
+			break
+		}
+		drawOGText(canvas, metaFace, line, 110, 355+i*34, color.RGBA{R: 0xd8, G: 0xd2, B: 0xff, A: 0xff})
+	}
+
+	button := image.Rect(110, 474, 430, 548)
+	draw.Draw(canvas, button, &image.Uniform{color.RGBA{R: 0x8b, G: 0x5c, B: 0xf6, A: 0xff}}, image.Point{}, draw.Src)
+	drawOGText(canvas, buttonFace, "Click to download", 142, 520, color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff})
+	drawOGText(canvas, metaFace, "warpbox.dev", 910, 520, color.RGBA{R: 0xaa, G: 0xa4, B: 0xd6, A: 0xff})
+	return canvas
+}
+
+func fileCardInfo(file services.File) string {
+	switch {
+	case strings.HasPrefix(file.ContentType, "audio/"):
+		return "Audio file shared through Warpbox. Open the link to preview in your browser or download the original."
+	case file.ContentType == "text/markdown":
+		return "Markdown file shared through Warpbox. Open the link to view the rendered preview, source, or download."
+	case strings.Contains(file.ContentType, "html"):
+		return "HTML file shared through Warpbox. Open the link to preview rendered HTML, source, or download."
+	case strings.Contains(file.ContentType, "pdf"):
+		return "PDF file shared through Warpbox. Open the link to download the original file."
+	case strings.HasPrefix(file.ContentType, "text/"):
+		return "Text file shared through Warpbox. Open the link to preview the content or download."
+	default:
+		return "File shared through Warpbox. Open the link to preview available details or download the original."
+	}
+}
+
+func (a *App) ogFont(size float64, bold bool) font.Face {
+	name := "PixeloidSans.ttf"
+	if bold {
+		name = "PixeloidSans-Bold.ttf"
+	}
+	data, err := os.ReadFile(filepath.Join(a.cfg.StaticDir, "fonts", "pixeloid_sans", name))
+	if err != nil {
+		return basicfont.Face7x13
+	}
+	parsed, err := opentype.Parse(data)
+	if err != nil {
+		return basicfont.Face7x13
+	}
+	face, err := opentype.NewFace(parsed, &opentype.FaceOptions{Size: size, DPI: 72, Hinting: font.HintingFull})
+	if err != nil {
+		return basicfont.Face7x13
+	}
+	return face
+}
+
+func drawOGText(dst *image.RGBA, face font.Face, text string, x, y int, c color.Color) {
+	d := font.Drawer{
+		Dst:  dst,
+		Src:  image.NewUniform(c),
+		Face: face,
+		Dot:  fixed.P(x, y),
+	}
+	d.DrawString(text)
+}
+
+func wrapOGText(text string, face font.Face, maxWidth int) []string {
+	words := strings.Fields(text)
+	if len(words) == 0 {
+		return []string{text}
+	}
+	lines := []string{}
+	current := words[0]
+	for _, word := range words[1:] {
+		next := current + " " + word
+		if ogTextWidth(face, next) <= maxWidth {
+			current = next
+			continue
+		}
+		lines = append(lines, current)
+		current = word
+	}
+	lines = append(lines, current)
+	return lines
+}
+
+func trimOGText(text string, face font.Face, maxWidth int) string {
+	for ogTextWidth(face, text+"...") > maxWidth && len(text) > 1 {
+		text = text[:len(text)-1]
+	}
+	return strings.TrimSpace(text) + "..."
+}
+
+func ogTextWidth(face font.Face, text string) int {
+	bounds, _ := font.BoundString(face, text)
+	return (bounds.Max.X - bounds.Min.X).Ceil()
+}
+
 // renderCollage tiles up to four thumbnails into the OG canvas with a small gap.
 func renderCollage(thumbs []image.Image) image.Image {
 	canvas := image.NewRGBA(image.Rect(0, 0, ogImageWidth, ogImageHeight))

backend/libs/handlers/pages.go

@@ -61,7 +61,10 @@ func (a *App) Home(w http.ResponseWriter, r *http.Request) {
 	expiryOptions, defaultExpiry := a.homeExpiryOptions(settings, user, loggedIn, isAdmin)
 	a.renderPage(w, r, http.StatusOK, "home.html", web.PageData{
 		Title:        "Upload your files",
-		Description: "Upload and share files through a self-hosted Warpbox instance.",
+		Description:  "Upload and share files fast. Drop a file, get a link — private, temporary transfers that expire on your terms.",
+		CanonicalURL: absoluteURL(r, "/"),
+		ImageURL:     absoluteURL(r, "/static/og-default.png"),
+		ImageAlt:     "Warp Box — simple file sharing and fast downloads",
 		CurrentUser:  currentUser,
 		Data: homeData{
 			MaxUploadSize:        maxUploadSize,
@@ -95,7 +98,7 @@ func (a *App) homeExpiryOptions(settings services.UploadPolicySettings, user ser
 }
 
 func buildExpiryOptions(maxDays int, unlimited bool) ([]expiryOption, int) {
-	ladder := []int{60, 720, 1440, 2880, 4320, 7200, 10080, 14400, 20160, 43200, 86400, 129600, 259200, 525600}
+	ladder := []int{60, 360, 720, 1440, 2880, 4320, 7200, 10080, 14400, 20160, 43200, 86400, 129600, 259200, 525600}
 
 	capMinutes := maxDays * 24 * 60
 	if unlimited || capMinutes <= 0 {

backend/libs/handlers/upload_stage3_test.go

@@ -106,7 +106,7 @@ func TestUploadTextResponseReturnsOnlyBoxURL(t *testing.T) {
 	}
 }
 
-func TestSocialPreviewBotGetsRawSingleFileBox(t *testing.T) {
+func TestSocialPreviewBotGetsCardForSingleNonMediaBox(t *testing.T) {
 	app, cleanup := newTestApp(t)
 	defer cleanup()
 	payload := uploadThroughApp(t, app)
@@ -120,15 +120,19 @@ func TestSocialPreviewBotGetsRawSingleFileBox(t *testing.T) {
 	if response.Code != http.StatusOK {
 		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
 	}
-	if strings.Contains(response.Body.String(), "Shared files on Warpbox") {
-		t.Fatalf("social preview bot received HTML download page")
+	body := response.Body.String()
+	if !strings.Contains(body, `/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/og-image.jpg"`) {
+		t.Fatalf("social preview bot did not receive file card metadata: %s", body)
 	}
-	if response.Body.String() != "hello" {
-		t.Fatalf("social preview body = %q", response.Body.String())
+	if !strings.Contains(body, `class="file-thumb" src="/d/`+payload.BoxID+`/thumb/`+payload.Files[0].ID+`"`) {
+		t.Fatalf("download page did not render text thumbnail image: %s", body)
+	}
+	if !strings.Contains(body, "Click to preview or download") && !strings.Contains(body, "click to preview or download") {
+		t.Fatalf("social preview body missing preview/download description: %s", body)
 	}
 }
 
-func TestSocialPreviewBotGetsRawFilePreview(t *testing.T) {
+func TestSocialPreviewBotGetsCardForNonMediaFilePreview(t *testing.T) {
 	app, cleanup := newTestApp(t)
 	defer cleanup()
 	payload := uploadThroughApp(t, app)
@@ -143,11 +147,74 @@ func TestSocialPreviewBotGetsRawFilePreview(t *testing.T) {
 	if response.Code != http.StatusOK {
 		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
 	}
-	if strings.Contains(response.Body.String(), "preview-title") {
-		t.Fatalf("social preview bot received HTML preview page")
+	body := response.Body.String()
+	if !strings.Contains(body, `/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/og-image.jpg"`) {
+		t.Fatalf("social preview bot did not receive file card metadata: %s", body)
+	}
+	if !strings.Contains(body, `name="twitter:card" content="summary_large_image"`) {
+		t.Fatalf("social preview body missing twitter card metadata: %s", body)
+	}
+}
+
+func TestSocialPreviewBotGetsRawImageFilePreview(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	request := multipartUploadRequest(t, "/api/v1/upload", "file", "image.png", "\x89PNG\r\n\x1a\nimage")
+	request.Header.Set("Accept", "application/json")
+	uploadResponse := httptest.NewRecorder()
+	app.Upload(uploadResponse, request)
+	if uploadResponse.Code != http.StatusCreated {
+		t.Fatalf("upload status = %d, body = %s", uploadResponse.Code, uploadResponse.Body.String())
+	}
+	var payload services.UploadResult
+	if err := json.Unmarshal(uploadResponse.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("json.Unmarshal returned error: %v", err)
+	}
+
+	previewRequest := httptest.NewRequest(http.MethodGet, "/d/"+payload.BoxID+"/f/"+payload.Files[0].ID, nil)
+	previewRequest.Header.Set("User-Agent", "Discordbot/2.0")
+	previewRequest.SetPathValue("boxID", payload.BoxID)
+	previewRequest.SetPathValue("fileID", payload.Files[0].ID)
+	response := httptest.NewRecorder()
+	app.DownloadFile(response, previewRequest)
+
+	if response.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
+	}
+	if strings.Contains(response.Body.String(), "preview-title") {
+		t.Fatalf("image social preview bot received HTML preview page")
+	}
+	if !strings.HasPrefix(response.Body.String(), "\x89PNG\r\n\x1a\n") {
+		t.Fatalf("image social preview body = %q", response.Body.String())
+	}
+}
+
+func TestFilePreviewPageIncludesPreviewMetadata(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+	payload := uploadThroughApp(t, app)
+
+	request := httptest.NewRequest(http.MethodGet, "/d/"+payload.BoxID+"/f/"+payload.Files[0].ID, nil)
+	request.SetPathValue("boxID", payload.BoxID)
+	request.SetPathValue("fileID", payload.Files[0].ID)
+	response := httptest.NewRecorder()
+	app.DownloadFile(response, request)
+
+	if response.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
+	}
+	body := response.Body.String()
+	for _, want := range []string{
+		`data-size-bytes="5"`,
+		`data-source-url="/d/` + payload.BoxID,
+		`data-download-url="/d/` + payload.BoxID,
+		`data-icon-url="/static/file-icons/`,
+		`data-preview-tabs`,
+	} {
+		if !strings.Contains(body, want) {
+			t.Fatalf("preview page missing %q: %s", want, body)
 		}
-	if response.Body.String() != "hello" {
-		t.Fatalf("social preview body = %q", response.Body.String())
 	}
 }
 

backend/libs/jobs/thumbnails.go

@@ -3,18 +3,27 @@ package jobs
 import (
 	"bytes"
 	"context"
+	"fmt"
+	"html"
 	"image"
+	"image/color"
+	"image/draw"
 	_ "image/gif"
 	"image/jpeg"
-	_ "image/jpeg"
 	_ "image/png"
 	"io"
 	"log/slog"
 	"os"
 	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/basicfont"
+	"golang.org/x/image/math/fixed"
 	_ "golang.org/x/image/webp"
 	"warpbox.dev/backend/libs/config"
 	"warpbox.dev/backend/libs/services"
@@ -101,26 +110,41 @@ func generateMissingThumbnailsForBox(uploadService *services.UploadService, logg
 	changed := false
 	for i := range box.Files {
 		file := &box.Files[i]
-		if file.Thumbnail != "" || !needsThumbnail(*file) {
+		needsPrimary := file.Thumbnail == "" && needsThumbnail(*file)
+		needsScenes := file.SceneThumbnail == "" && needsVideoScenes(*file)
+		if !needsPrimary && !needsScenes {
 			continue
 		}
 		result.Scanned++
 
+		if needsPrimary {
 			thumbnail, err := generateThumbnail(uploadService, box, *file)
 			if err != nil {
 				logger.Warn("thumbnail generation failed", "source", "thumbnail", "severity", "warn", "code", 4101, "file_id", file.ID, "error", err.Error())
 				result.Failed++
-			continue
-		}
-		if thumbnail == "" {
+			} else if thumbnail == "" {
 				result.Failed++
-			continue
-		}
-
+			} else {
 				file.Thumbnail = thumbnail
 				changed = true
 				result.Generated++
 			}
+		}
+
+		if needsScenes {
+			sceneThumbnail, err := generateVideoScenesThumbnail(uploadService, box, *file)
+			if err != nil {
+				logger.Warn("video scenes preview generation failed", "source", "thumbnail", "severity", "warn", "code", 4104, "file_id", file.ID, "error", err.Error())
+				result.Failed++
+			} else if sceneThumbnail == "" {
+				result.Failed++
+			} else {
+				file.SceneThumbnail = sceneThumbnail
+				changed = true
+				result.Generated++
+			}
+		}
+	}
 
 	if changed {
 		if err := uploadService.SaveBox(box); err != nil {
@@ -131,7 +155,27 @@ func generateMissingThumbnailsForBox(uploadService *services.UploadService, logg
 }
 
 func needsThumbnail(file services.File) bool {
-	return file.PreviewKind == "image" || file.PreviewKind == "video"
+	return file.PreviewKind == "image" || file.PreviewKind == "video" || isTextThumbnailCandidate(file)
+}
+
+func needsVideoScenes(file services.File) bool {
+	return file.PreviewKind == "video" || strings.HasPrefix(strings.ToLower(file.ContentType), "video/")
+}
+
+func NeedsThumbnail(file services.File) bool {
+	return needsThumbnail(file)
+}
+
+func NeedsVideoScenes(file services.File) bool {
+	return needsVideoScenes(file)
+}
+
+func GenerateThumbnailForFile(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
+	return generateThumbnail(uploadService, box, file)
+}
+
+func GenerateVideoScenesForFile(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
+	return generateVideoScenesThumbnail(uploadService, box, file)
 }
 
 func generateThumbnail(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
@@ -157,11 +201,58 @@ func generateThumbnail(uploadService *services.UploadService, box services.Box,
 		}
 		_, err = uploadService.PutThumbnailObject(context.Background(), box, thumbnailName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
 		return thumbnailName, err
+	case isTextThumbnailCandidate(file):
+		data, err := createTextThumbnail(file, object.Body)
+		if err != nil {
+			return "", err
+		}
+		_, err = uploadService.PutThumbnailObject(context.Background(), box, thumbnailName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
+		return thumbnailName, err
 	default:
 		return "", nil
 	}
 }
 
+func generateVideoScenesThumbnail(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
+	if !needsVideoScenes(file) {
+		return "", nil
+	}
+	sceneName := "@scene@" + file.ID + ".jpg"
+	object, err := uploadService.OpenFileObject(context.Background(), box, file)
+	if err != nil {
+		return "", err
+	}
+	defer object.Body.Close()
+
+	data, err := createVideoScenesThumbnail(file, object.Body)
+	if err != nil {
+		return "", err
+	}
+	_, err = uploadService.PutThumbnailObject(context.Background(), box, sceneName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
+	return sceneName, err
+}
+
+func isTextThumbnailCandidate(file services.File) bool {
+	contentType := strings.ToLower(strings.TrimSpace(file.ContentType))
+	if i := strings.IndexByte(contentType, ';'); i >= 0 {
+		contentType = strings.TrimSpace(contentType[:i])
+	}
+	if strings.HasPrefix(contentType, "text/") {
+		return true
+	}
+	switch contentType {
+	case "application/json", "application/ld+json", "application/xml", "application/javascript", "application/x-javascript", "application/markdown":
+		return true
+	}
+	ext := strings.TrimPrefix(strings.ToLower(filepath.Ext(file.Name)), ".")
+	switch ext {
+	case "c", "cc", "conf", "cpp", "cs", "css", "csv", "diff", "dockerfile", "go", "h", "hpp", "htm", "html", "ini", "java", "js", "json", "jsx", "kt", "log", "lua", "md", "mdown", "markdown", "php", "pl", "properties", "py", "rb", "rs", "sh", "sql", "swift", "toml", "ts", "tsx", "txt", "xml", "yaml", "yml", "zig":
+		return true
+	default:
+		return false
+	}
+}
+
 func createImageThumbnail(source io.Reader) ([]byte, error) {
 	img, _, err := image.Decode(source)
 	if err != nil {
@@ -190,17 +281,511 @@ func createVideoThumbnail(source io.Reader) ([]byte, error) {
 	if err := sourceFile.Close(); err != nil {
 		return nil, err
 	}
+	sourcePath := sourceFile.Name()
+	candidates := []string{"00:00:01", "00:00:03", "00:00:06"}
+	var fallback []byte
+	for _, timestamp := range candidates {
 		targetFile, err := os.CreateTemp("", "warpbox-thumb-*.jpg")
 		if err != nil {
 			return nil, err
 		}
 		targetPath := targetFile.Name()
 		targetFile.Close()
-	defer os.Remove(targetPath)
-	if err := exec.Command("ffmpeg", "-y", "-loglevel", "error", "-ss", "00:00:01", "-i", sourceFile.Name(), "-frames:v", "1", "-vf", "scale=360:-1", targetPath).Run(); err != nil {
+		if err := extractVideoFrame(sourcePath, timestamp, targetPath, "scale=360:-1"); err != nil {
+			os.Remove(targetPath)
+			continue
+		}
+		data, err := os.ReadFile(targetPath)
+		os.Remove(targetPath)
+		if err != nil {
+			continue
+		}
+		if len(fallback) == 0 {
+			fallback = data
+		}
+		if usableVideoFrame(data) {
+			return data, nil
+		}
+	}
+
+	scenes, err := createVideoScenesThumbnailFromPath(services.File{Name: "video", ContentType: "video"}, sourcePath)
+	if err == nil {
+		img, err := jpeg.Decode(bytes.NewReader(scenes))
+		if err == nil {
+			thumb := resizeNearest(img, 360, 240)
+			var target bytes.Buffer
+			if err := jpeg.Encode(&target, thumb, &jpeg.Options{Quality: 82}); err == nil {
+				return target.Bytes(), nil
+			}
+		}
+	}
+	if len(fallback) > 0 {
+		return fallback, nil
+	}
+	return nil, fmt.Errorf("could not extract a usable video thumbnail")
+}
+
+func createVideoScenesThumbnail(file services.File, source io.Reader) ([]byte, error) {
+	sourceFile, err := os.CreateTemp("", "warpbox-video-*")
+	if err != nil {
 		return nil, err
 	}
-	return os.ReadFile(targetPath)
+	defer os.Remove(sourceFile.Name())
+	if _, err := io.Copy(sourceFile, source); err != nil {
+		sourceFile.Close()
+		return nil, err
+	}
+	if err := sourceFile.Close(); err != nil {
+		return nil, err
+	}
+	return createVideoScenesThumbnailFromPath(file, sourceFile.Name())
+}
+
+func createVideoScenesThumbnailFromPath(file services.File, sourcePath string) ([]byte, error) {
+	info := probeVideoInfo(sourcePath, file)
+	timestamps := videoSceneTimestamps(info.Duration)
+	frames := make([]videoSceneFrame, 0, len(timestamps))
+
+	for _, timestamp := range timestamps {
+		targetFile, err := os.CreateTemp("", "warpbox-scene-*.jpg")
+		if err != nil {
+			continue
+		}
+		targetPath := targetFile.Name()
+		targetFile.Close()
+		if err := extractVideoFrame(sourcePath, timestamp, targetPath, "scale=640:-1"); err != nil {
+			os.Remove(targetPath)
+			continue
+		}
+		data, err := os.ReadFile(targetPath)
+		os.Remove(targetPath)
+		if err != nil {
+			continue
+		}
+		img, err := jpeg.Decode(bytes.NewReader(data))
+		if err != nil {
+			continue
+		}
+		frames = append(frames, videoSceneFrame{Timestamp: timestamp, Image: img})
+	}
+
+	return renderVideoScenesThumbnail(file, info, frames), nil
+}
+
+func extractVideoFrame(sourcePath, timestamp, targetPath, scaleFilter string) error {
+	return exec.Command("ffmpeg", "-y", "-loglevel", "error", "-ss", timestamp, "-i", sourcePath, "-frames:v", "1", "-vf", scaleFilter, targetPath).Run()
+}
+
+type videoSceneFrame struct {
+	Timestamp string
+	Image     image.Image
+}
+
+type videoInfo struct {
+	Codec     string
+	Width     int
+	Height    int
+	Duration  float64
+	FrameRate string
+}
+
+func probeVideoInfo(sourcePath string, file services.File) videoInfo {
+	info := videoInfo{Codec: "unknown", FrameRate: "unknown"}
+	output, err := exec.Command("ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=codec_name,width,height,duration,avg_frame_rate", "-of", "default=noprint_wrappers=1", sourcePath).Output()
+	if err != nil {
+		if file.ContentType != "" {
+			info.Codec = file.ContentType
+		}
+		return info
+	}
+	for _, line := range strings.Split(string(output), "\n") {
+		key, value, ok := strings.Cut(strings.TrimSpace(line), "=")
+		if !ok || value == "" || value == "N/A" {
+			continue
+		}
+		switch key {
+		case "codec_name":
+			info.Codec = value
+		case "width":
+			info.Width, _ = strconv.Atoi(value)
+		case "height":
+			info.Height, _ = strconv.Atoi(value)
+		case "duration":
+			info.Duration, _ = strconv.ParseFloat(value, 64)
+		case "avg_frame_rate":
+			info.FrameRate = simplifyFrameRate(value)
+		}
+	}
+	return info
+}
+
+func simplifyFrameRate(value string) string {
+	if value == "0/0" || value == "" {
+		return "unknown"
+	}
+	parts := strings.Split(value, "/")
+	if len(parts) != 2 {
+		return value
+	}
+	n, errN := strconv.ParseFloat(parts[0], 64)
+	d, errD := strconv.ParseFloat(parts[1], 64)
+	if errN != nil || errD != nil || d == 0 {
+		return value
+	}
+	return fmt.Sprintf("%.2f fps", n/d)
+}
+
+func videoSceneTimestamps(duration float64) []string {
+	if duration > 4 {
+		points := []float64{0.12, 0.33, 0.58, 0.82}
+		timestamps := make([]string, 0, len(points))
+		for _, point := range points {
+			seconds := duration * point
+			if seconds < 1 {
+				seconds = 1
+			}
+			timestamps = append(timestamps, secondsToTimestamp(seconds))
+		}
+		return timestamps
+	}
+	return []string{"00:00:01", "00:00:03", "00:00:06", "00:00:10"}
+}
+
+func secondsToTimestamp(seconds float64) string {
+	total := int(seconds + 0.5)
+	hours := total / 3600
+	minutes := total % 3600 / 60
+	secs := total % 60
+	return fmt.Sprintf("%02d:%02d:%02d", hours, minutes, secs)
+}
+
+func usableVideoFrame(data []byte) bool {
+	img, err := jpeg.Decode(bytes.NewReader(data))
+	if err != nil {
+		return false
+	}
+	return averageLuma(img) >= 18
+}
+
+func averageLuma(img image.Image) float64 {
+	bounds := img.Bounds()
+	width := bounds.Dx()
+	height := bounds.Dy()
+	if width <= 0 || height <= 0 {
+		return 0
+	}
+	stepX := max(1, width/80)
+	stepY := max(1, height/80)
+	var total float64
+	var samples int
+	for y := bounds.Min.Y; y < bounds.Max.Y; y += stepY {
+		for x := bounds.Min.X; x < bounds.Max.X; x += stepX {
+			r, g, b, _ := img.At(x, y).RGBA()
+			total += 0.2126*float64(r>>8) + 0.7152*float64(g>>8) + 0.0722*float64(b>>8)
+			samples++
+		}
+	}
+	if samples == 0 {
+		return 0
+	}
+	return total / float64(samples)
+}
+
+func renderVideoScenesThumbnail(file services.File, info videoInfo, frames []videoSceneFrame) []byte {
+	canvas := image.NewRGBA(image.Rect(0, 0, 1200, 630))
+	drawSolid(canvas, canvas.Bounds(), color.RGBA{R: 0x0b, G: 0x0b, B: 0x12, A: 0xff})
+	drawSolid(canvas, image.Rect(0, 0, 1200, 630), color.RGBA{R: 0x10, G: 0x13, B: 0x1f, A: 0xff})
+	drawSolid(canvas, image.Rect(36, 36, 1164, 594), color.RGBA{R: 0x17, G: 0x17, B: 0x22, A: 0xff})
+	drawSolid(canvas, image.Rect(36, 36, 1164, 96), color.RGBA{R: 0x20, G: 0x1b, B: 0x34, A: 0xff})
+	drawSolid(canvas, image.Rect(36, 96, 1164, 100), color.RGBA{R: 0x7c, G: 0x3a, B: 0xed, A: 0xff})
+
+	face := basicfont.Face7x13
+	drawThumbText(canvas, face, "VIDEO SCENES PREVIEW", 62, 63, color.RGBA{R: 0xc4, G: 0xb5, B: 0xfd, A: 0xff})
+	drawThumbText(canvas, face, trimThumbnailText(file.Name, 72), 62, 84, color.RGBA{R: 0xff, G: 0xfb, B: 0xeb, A: 0xff})
+
+	meta := videoMetaLines(file, info)
+	y := 122
+	for _, line := range meta {
+		drawThumbText(canvas, face, line, 62, y, color.RGBA{R: 0xcb, G: 0xd5, B: 0xe1, A: 0xff})
+		y += 20
+	}
+
+	cells := []image.Rectangle{
+		image.Rect(62, 212, 586, 388),
+		image.Rect(614, 212, 1138, 388),
+		image.Rect(62, 414, 586, 566),
+		image.Rect(614, 414, 1138, 566),
+	}
+	for i, rect := range cells {
+		drawSolid(canvas, rect, color.RGBA{R: 0x0f, G: 0x17, B: 0x22, A: 0xff})
+		if i < len(frames) {
+			drawImageCover(canvas, rect, frames[i].Image)
+			drawSolid(canvas, image.Rect(rect.Min.X, rect.Min.Y, rect.Min.X+88, rect.Min.Y+24), color.RGBA{R: 0x00, G: 0x00, B: 0x00, A: 0xcc})
+			drawThumbText(canvas, face, frames[i].Timestamp, rect.Min.X+10, rect.Min.Y+17, color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff})
+		} else {
+			drawThumbText(canvas, face, "No frame available", rect.Min.X+18, rect.Min.Y+34, color.RGBA{R: 0x94, G: 0xa3, B: 0xb8, A: 0xff})
+		}
+	}
+
+	var target bytes.Buffer
+	_ = jpeg.Encode(&target, canvas, &jpeg.Options{Quality: 86})
+	return target.Bytes()
+}
+
+func videoMetaLines(file services.File, info videoInfo) []string {
+	resolution := "unknown resolution"
+	if info.Width > 0 && info.Height > 0 {
+		resolution = fmt.Sprintf("%dx%d", info.Width, info.Height)
+	}
+	duration := "unknown duration"
+	if info.Duration > 0 {
+		duration = secondsToHumanDuration(info.Duration)
+	}
+	contentType := file.ContentType
+	if contentType == "" {
+		contentType = "video"
+	}
+	return []string{
+		"Duration: " + duration + "     Codec: " + info.Codec,
+		"Resolution: " + resolution + "     Frame rate: " + info.FrameRate,
+		"Type: " + contentType + "     Generated by Warpbox",
+	}
+}
+
+func secondsToHumanDuration(seconds float64) string {
+	total := int(seconds + 0.5)
+	hours := total / 3600
+	minutes := total % 3600 / 60
+	secs := total % 60
+	if hours > 0 {
+		return fmt.Sprintf("%d:%02d:%02d", hours, minutes, secs)
+	}
+	return fmt.Sprintf("%d:%02d", minutes, secs)
+}
+
+func drawImageCover(dst *image.RGBA, rect image.Rectangle, src image.Image) {
+	bounds := src.Bounds()
+	srcW := bounds.Dx()
+	srcH := bounds.Dy()
+	dstW := rect.Dx()
+	dstH := rect.Dy()
+	if srcW <= 0 || srcH <= 0 || dstW <= 0 || dstH <= 0 {
+		return
+	}
+
+	srcRatio := float64(srcW) / float64(srcH)
+	dstRatio := float64(dstW) / float64(dstH)
+	crop := bounds
+	if srcRatio > dstRatio {
+		newW := int(float64(srcH) * dstRatio)
+		x0 := bounds.Min.X + (srcW-newW)/2
+		crop = image.Rect(x0, bounds.Min.Y, x0+newW, bounds.Max.Y)
+	} else if srcRatio < dstRatio {
+		newH := int(float64(srcW) / dstRatio)
+		y0 := bounds.Min.Y + (srcH-newH)/2
+		crop = image.Rect(bounds.Min.X, y0, bounds.Max.X, y0+newH)
+	}
+
+	for y := rect.Min.Y; y < rect.Max.Y; y++ {
+		for x := rect.Min.X; x < rect.Max.X; x++ {
+			u := float64(x-rect.Min.X) / float64(dstW)
+			v := float64(y-rect.Min.Y) / float64(dstH)
+			srcX := crop.Min.X + min(crop.Dx()-1, int(u*float64(crop.Dx())))
+			srcY := crop.Min.Y + min(crop.Dy()-1, int(v*float64(crop.Dy())))
+			dst.Set(x, y, src.At(srcX, srcY))
+		}
+	}
+}
+
+func createTextThumbnail(file services.File, source io.Reader) ([]byte, error) {
+	data, err := io.ReadAll(io.LimitReader(source, 128*1024))
+	if err != nil {
+		return nil, err
+	}
+	sourceText := strings.ReplaceAll(string(data), "\r\n", "\n")
+	sourceText = strings.ReplaceAll(sourceText, "\r", "\n")
+
+	mode := textThumbnailMode(file)
+	title := strings.ToUpper(mode)
+	var lines []string
+	if mode == "HTML" {
+		lines = renderedHTMLThumbnailLines(sourceText)
+	} else if mode == "MARKDOWN" {
+		lines = renderedMarkdownThumbnailLines(sourceText)
+	} else {
+		title = "CODE"
+		lines = codeThumbnailLines(sourceText)
+	}
+	return renderTextThumbnail(file.Name, title, lines), nil
+}
+
+func textThumbnailMode(file services.File) string {
+	contentType := strings.ToLower(strings.TrimSpace(file.ContentType))
+	if i := strings.IndexByte(contentType, ';'); i >= 0 {
+		contentType = strings.TrimSpace(contentType[:i])
+	}
+	ext := strings.TrimPrefix(strings.ToLower(filepath.Ext(file.Name)), ".")
+	if ext == "html" || ext == "htm" || contentType == "text/html" {
+		return "HTML"
+	}
+	if ext == "md" || ext == "mdown" || ext == "markdown" || contentType == "text/markdown" || contentType == "application/markdown" {
+		return "MARKDOWN"
+	}
+	return "CODE"
+}
+
+func renderedHTMLThumbnailLines(source string) []string {
+	text := regexp.MustCompile(`(?is)<script[^>]*>.*?</script>`).ReplaceAllString(source, " ")
+	text = regexp.MustCompile(`(?is)<style[^>]*>.*?</style>`).ReplaceAllString(text, " ")
+	text = regexp.MustCompile(`(?i)</?(p|div|section|article|main|header|footer|br|li|ul|ol|h[1-6]|tr|table|blockquote|pre|code)[^>]*>`).ReplaceAllString(text, "\n")
+	text = regexp.MustCompile(`(?s)<[^>]+>`).ReplaceAllString(text, " ")
+	text = html.UnescapeString(text)
+	return documentThumbnailLines(text)
+}
+
+func renderedMarkdownThumbnailLines(source string) []string {
+	text := regexp.MustCompile("(?s)```.*?```").ReplaceAllStringFunc(source, func(block string) string {
+		block = strings.Trim(block, "` \n\t")
+		lines := strings.Split(block, "\n")
+		if len(lines) > 1 {
+			lines = lines[1:]
+		}
+		return "\n" + strings.Join(lines, "\n") + "\n"
+	})
+	text = regexp.MustCompile(`(?m)^#{1,6}\s*`).ReplaceAllString(text, "")
+	text = regexp.MustCompile(`!\[([^\]]*)\]\([^)]+\)`).ReplaceAllString(text, "$1")
+	text = regexp.MustCompile(`\[([^\]]+)\]\([^)]+\)`).ReplaceAllString(text, "$1")
+	text = regexp.MustCompile("`([^`]+)`").ReplaceAllString(text, "$1")
+	text = strings.NewReplacer("**", "", "__", "", "*", "", "_", "", "~~", "").Replace(text)
+	return documentThumbnailLines(text)
+}
+
+func documentThumbnailLines(source string) []string {
+	source = regexp.MustCompile(`[ \t]+`).ReplaceAllString(source, " ")
+	rawLines := strings.Split(source, "\n")
+	lines := make([]string, 0, 9)
+	for _, raw := range rawLines {
+		raw = strings.TrimSpace(raw)
+		if raw == "" {
+			continue
+		}
+		for _, line := range wrapTextThumbnailLine(raw, 43) {
+			lines = append(lines, line)
+			if len(lines) >= 9 {
+				return lines
+			}
+		}
+	}
+	if len(lines) == 0 {
+		return []string{"Rendered preview is empty."}
+	}
+	return lines
+}
+
+func codeThumbnailLines(source string) []string {
+	rawLines := strings.Split(source, "\n")
+	lines := make([]string, 0, 10)
+	for _, raw := range rawLines {
+		raw = strings.ReplaceAll(raw, "\t", "  ")
+		raw = strings.TrimRight(raw, " ")
+		if strings.TrimSpace(raw) == "" && len(lines) == 0 {
+			continue
+		}
+		if len(raw) > 48 {
+			raw = raw[:45] + "..."
+		}
+		lines = append(lines, raw)
+		if len(lines) >= 10 {
+			break
+		}
+	}
+	if len(lines) == 0 {
+		return []string{"(empty file)"}
+	}
+	return lines
+}
+
+func renderTextThumbnail(name, mode string, lines []string) []byte {
+	canvas := image.NewRGBA(image.Rect(0, 0, 360, 240))
+	drawSolid(canvas, canvas.Bounds(), color.RGBA{R: 0x0b, G: 0x0b, B: 0x16, A: 0xff})
+	drawSolid(canvas, image.Rect(10, 10, 350, 230), color.RGBA{R: 0x17, G: 0x14, B: 0x2d, A: 0xff})
+	drawSolid(canvas, image.Rect(10, 10, 350, 16), color.RGBA{R: 0xa7, G: 0x8b, B: 0xfa, A: 0xff})
+
+	face := basicfont.Face7x13
+	drawThumbText(canvas, face, trimThumbnailText(name, 38), 22, 36, color.RGBA{R: 0xf5, G: 0xf3, B: 0xff, A: 0xff})
+	drawThumbText(canvas, face, mode+" PREVIEW", 22, 55, color.RGBA{R: 0x67, G: 0xe8, B: 0xf9, A: 0xff})
+
+	codePane := image.Rect(22, 72, 338, 210)
+	if mode == "CODE" {
+		drawSolid(canvas, codePane, color.RGBA{R: 0x0f, G: 0x11, B: 0x1a, A: 0xff})
+	} else {
+		drawSolid(canvas, codePane, color.RGBA{R: 0x21, G: 0x1b, B: 0x3e, A: 0xff})
+	}
+
+	y := 91
+	for _, line := range lines {
+		drawThumbText(canvas, face, line, 32, y, color.RGBA{R: 0xf8, G: 0xfa, B: 0xfc, A: 0xff})
+		y += 14
+		if y > 202 {
+			break
+		}
+	}
+
+	var target bytes.Buffer
+	_ = jpeg.Encode(&target, canvas, &jpeg.Options{Quality: 84})
+	return target.Bytes()
+}
+
+func drawSolid(dst *image.RGBA, rect image.Rectangle, c color.Color) {
+	draw.Draw(dst, rect, &image.Uniform{c}, image.Point{}, draw.Src)
+}
+
+func drawThumbText(dst *image.RGBA, face font.Face, text string, x, y int, c color.Color) {
+	d := font.Drawer{
+		Dst:  dst,
+		Src:  image.NewUniform(c),
+		Face: face,
+		Dot:  fixed.P(x, y),
+	}
+	d.DrawString(text)
+}
+
+func wrapTextThumbnailLine(text string, maxChars int) []string {
+	if len(text) <= maxChars {
+		return []string{text}
+	}
+	words := strings.Fields(text)
+	if len(words) == 0 {
+		return []string{text[:maxChars-3] + "..."}
+	}
+	lines := []string{}
+	current := ""
+	for _, word := range words {
+		if current == "" {
+			current = word
+			continue
+		}
+		if len(current)+1+len(word) <= maxChars {
+			current += " " + word
+			continue
+		}
+		lines = append(lines, trimThumbnailText(current, maxChars))
+		current = word
+	}
+	if current != "" {
+		lines = append(lines, trimThumbnailText(current, maxChars))
+	}
+	return lines
+}
+
+func trimThumbnailText(text string, maxChars int) string {
+	if len(text) <= maxChars {
+		return text
+	}
+	if maxChars <= 3 {
+		return text[:maxChars]
+	}
+	return strings.TrimSpace(text[:maxChars-3]) + "..."
 }
 
 func resizeNearest(src image.Image, maxWidth, maxHeight int) *image.RGBA {

backend/libs/jobs/thumbnails_test.go

@@ -4,12 +4,14 @@ import (
 	"bytes"
 	"image"
 	"image/color"
+	"image/jpeg"
 	"image/png"
 	"io"
 	"log/slog"
 	"mime/multipart"
 	"net/http/httptest"
 	"net/textproto"
+	"strings"
 	"testing"
 
 	"warpbox.dev/backend/libs/services"
@@ -46,6 +48,76 @@ func TestGenerateMissingThumbnailsForBox(t *testing.T) {
 	}
 }
 
+func TestCreateTextThumbnailRendersMarkdownAsJPEG(t *testing.T) {
+	data, err := createTextThumbnail(services.File{
+		Name:        "notes.md",
+		ContentType: "text/markdown",
+	}, strings.NewReader("# Meeting notes\n\n```go\nfunc main() {}\n```\n\nA rendered Markdown preview."))
+	if err != nil {
+		t.Fatalf("createTextThumbnail returned error: %v", err)
+	}
+
+	img, err := jpeg.Decode(bytes.NewReader(data))
+	if err != nil {
+		t.Fatalf("jpeg.Decode returned error: %v", err)
+	}
+	if img.Bounds().Dx() != 360 || img.Bounds().Dy() != 240 {
+		t.Fatalf("thumbnail size = %dx%d, want 360x240", img.Bounds().Dx(), img.Bounds().Dy())
+	}
+}
+
+func TestNeedsThumbnailIncludesCodeTextFiles(t *testing.T) {
+	if !needsThumbnail(services.File{Name: "main.go", ContentType: "text/plain"}) {
+		t.Fatalf("Go source file should get a text thumbnail")
+	}
+}
+
+func TestUsableVideoFrameRejectsBlackFrame(t *testing.T) {
+	var dark bytes.Buffer
+	if err := jpeg.Encode(&dark, solidTestImage(color.RGBA{A: 255}), nil); err != nil {
+		t.Fatalf("jpeg.Encode dark returned error: %v", err)
+	}
+	if usableVideoFrame(dark.Bytes()) {
+		t.Fatalf("black video frame should not be usable")
+	}
+
+	var bright bytes.Buffer
+	if err := jpeg.Encode(&bright, solidTestImage(color.RGBA{R: 180, G: 80, B: 40, A: 255}), nil); err != nil {
+		t.Fatalf("jpeg.Encode bright returned error: %v", err)
+	}
+	if !usableVideoFrame(bright.Bytes()) {
+		t.Fatalf("bright video frame should be usable")
+	}
+}
+
+func TestRenderVideoScenesThumbnailReturnsLargeJPEG(t *testing.T) {
+	data := renderVideoScenesThumbnail(
+		services.File{Name: "clip.mp4", ContentType: "video/mp4"},
+		videoInfo{Codec: "h264", Width: 1920, Height: 1080, Duration: 125, FrameRate: "24.00 fps"},
+		[]videoSceneFrame{
+			{Timestamp: "00:00:10", Image: solidTestImage(color.RGBA{R: 140, G: 40, B: 80, A: 255})},
+			{Timestamp: "00:00:35", Image: solidTestImage(color.RGBA{R: 40, G: 120, B: 150, A: 255})},
+		},
+	)
+	img, err := jpeg.Decode(bytes.NewReader(data))
+	if err != nil {
+		t.Fatalf("jpeg.Decode returned error: %v", err)
+	}
+	if img.Bounds().Dx() != 1200 || img.Bounds().Dy() != 630 {
+		t.Fatalf("scene preview size = %dx%d, want 1200x630", img.Bounds().Dx(), img.Bounds().Dy())
+	}
+}
+
+func solidTestImage(c color.Color) image.Image {
+	img := image.NewRGBA(image.Rect(0, 0, 32, 24))
+	for y := 0; y < img.Bounds().Dy(); y++ {
+		for x := 0; x < img.Bounds().Dx(); x++ {
+			img.Set(x, y, c)
+		}
+	}
+	return img
+}
+
 func newThumbnailTestUploadService(t *testing.T) *services.UploadService {
 	t.Helper()
 	service, err := services.NewUploadService(1024*1024, t.TempDir(), "http://example.test", slog.New(slog.NewTextHandler(io.Discard, nil)))

backend/libs/middleware/security.go

@@ -9,7 +9,7 @@ func SecurityHeaders(next http.Handler) http.Handler {
 		header.Set("X-Frame-Options", "DENY")
 		header.Set("Referrer-Policy", "strict-origin-when-cross-origin")
 		header.Set("Permissions-Policy", "camera=(), microphone=(), geolocation=()")
-		header.Set("Content-Security-Policy", "default-src 'self'; img-src 'self' data: blob:; media-src 'self' blob:; font-src 'self'; style-src 'self'; script-src 'self'; base-uri 'self'; frame-ancestors 'none'")
+		header.Set("Content-Security-Policy", "default-src 'self'; img-src 'self' data: blob:; media-src 'self' blob:; font-src 'self'; style-src 'self' 'unsafe-inline'; script-src 'self'; frame-src 'self' about:; base-uri 'self'; frame-ancestors 'none'")
 
 		next.ServeHTTP(w, r)
 	})

backend/libs/services/upload.go

@@ -128,8 +128,10 @@ type File struct {
 	ContentType             string    `json:"contentType"`
 	PreviewKind             string    `json:"previewKind"`
 	Thumbnail               string    `json:"thumbnail,omitempty"`
+	SceneThumbnail          string    `json:"sceneThumbnail,omitempty"`
 	ObjectKey               string    `json:"objectKey,omitempty"`
 	ThumbnailObjectKey      string    `json:"thumbnailObjectKey,omitempty"`
+	SceneThumbnailObjectKey string    `json:"sceneThumbnailObjectKey,omitempty"`
 	Processing              bool      `json:"processing,omitempty"`
 	ProcessingError         string    `json:"processingError,omitempty"`
 	UploadedAt              time.Time `json:"uploadedAt"`
@@ -397,7 +399,7 @@ func (s *UploadService) writeIncomingFilesToBox(ctx context.Context, box *Box, f
 		storedName := "@each@" + fileID + strings.ToLower(filepath.Ext(incoming.Name()))
 		objectKey := boxObjectKey(box.ID, storedName)
 		contentType := incoming.ContentType()
-		if contentType == "" {
+		if contentType == "" || contentType == "application/octet-stream" {
 			buffer := make([]byte, 512)
 			n, _ := file.Read(buffer)
 			contentType = http.DetectContentType(buffer[:n])
@@ -731,6 +733,9 @@ func (s *UploadService) RemoveFileFromBox(boxID, fileID string) (bool, error) {
 		if key := s.ThumbnailObjectKey(box, file); key != "" {
 			_ = backend.Delete(context.Background(), key)
 		}
+		if key := s.SceneThumbnailObjectKey(box, file); key != "" {
+			_ = backend.Delete(context.Background(), key)
+		}
 	}
 
 	box.Files = append(box.Files[:index], box.Files[index+1:]...)
@@ -818,6 +823,16 @@ func (s *UploadService) ThumbnailObjectKey(box Box, file File) string {
 	return boxObjectKey(box.ID, file.Thumbnail)
 }
 
+func (s *UploadService) SceneThumbnailObjectKey(box Box, file File) string {
+	if file.SceneThumbnailObjectKey != "" {
+		return file.SceneThumbnailObjectKey
+	}
+	if file.SceneThumbnail == "" {
+		return ""
+	}
+	return boxObjectKey(box.ID, file.SceneThumbnail)
+}
+
 func (s *UploadService) OpenFileObject(ctx context.Context, box Box, file File) (StorageObject, error) {
 	if file.Processing {
 		return StorageObject{}, fmt.Errorf("file is still processing")
@@ -841,6 +856,18 @@ func (s *UploadService) OpenThumbnailObject(ctx context.Context, box Box, file F
 	return backend.Get(ctx, key)
 }
 
+func (s *UploadService) OpenSceneThumbnailObject(ctx context.Context, box Box, file File) (StorageObject, error) {
+	key := s.SceneThumbnailObjectKey(box, file)
+	if key == "" {
+		return StorageObject{}, os.ErrNotExist
+	}
+	backend, err := s.storage.Backend(s.BoxStorageBackendID(box))
+	if err != nil {
+		return StorageObject{}, err
+	}
+	return backend.Get(ctx, key)
+}
+
 func (s *UploadService) PutThumbnailObject(ctx context.Context, box Box, name string, body io.Reader, size int64, contentType string) (string, error) {
 	backend, err := s.storage.Backend(s.BoxStorageBackendID(box))
 	if err != nil {

backend/libs/services/upload_test.go

@@ -360,14 +360,14 @@ func TestResumableCleanupRemovesExpiredSessionsAndChunks(t *testing.T) {
 		Name:        "note.txt",
 		Size:        4,
 		ContentType: "text/plain",
-	}}, UploadOptions{MaxDays: 1}, 4, time.Millisecond, "")
+	}}, UploadOptions{MaxDays: 1}, 4, time.Hour, "")
 	if err != nil {
 		t.Fatalf("CreateResumableSession returned error: %v", err)
 	}
 	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, 0, strings.NewReader("hell")); err != nil {
 		t.Fatalf("PutResumableChunk returned error: %v", err)
 	}
-	cleaned, err := service.CleanupExpiredResumableSessions(time.Now().UTC().Add(time.Hour))
+	cleaned, err := service.CleanupExpiredResumableSessions(session.ExpiresAt.Add(time.Second))
 	if err != nil {
 		t.Fatalf("CleanupExpiredResumableSessions returned error: %v", err)
 	}

backend/libs/web/renderer.go

@@ -7,6 +7,9 @@ import (
 	"time"
 )
 
+// RobotsNone is used for private, protected, expired, or temporary pages.
+const RobotsNone = "noindex,nofollow,noarchive"
+
 type Renderer struct {
 	templates  map[string]*template.Template
 	appName    string
@@ -18,9 +21,16 @@ type PageData struct {
 	AppName      string
 	AppVersion   string
 	BaseURL      string
+	CanonicalURL string
+	Robots       string
+	OGType       string
 	Title        string
 	Description  string
 	ImageURL     string
+	ImageAlt     string
+	ImageType    string
+	MediaURL     string
+	MediaType    string
 	CurrentYear  int
 	CurrentUser  any
 	CSRFToken    string

backend/static/css/20-upload.css

@@ -52,6 +52,10 @@
   margin-top: -0.25rem;
 }
 
+.upload-options .form-footer .upload-new-button[hidden] {
+  display: none !important;
+}
+
 .hero-copy {
   text-align: center;
 }

backend/static/css/30-download.css

@@ -15,6 +15,379 @@
   text-align: center;
 }
 
+.preview-view {
+  width: min(72rem, calc(100% - 2rem));
+  min-height: auto;
+  padding-block: clamp(2rem, 7vh, 4.5rem);
+  display: block;
+}
+
+.preview-card {
+  width: 100%;
+  margin: 0 auto;
+  text-align: left;
+}
+
+.preview-card .card-content {
+  padding: clamp(1rem, 2.4vw, 1.5rem);
+}
+
+.preview-header {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 1rem;
+  margin-bottom: 1rem;
+}
+
+.preview-title-group {
+  min-width: 0;
+}
+
+.preview-header .file-name {
+  margin: 0;
+  font-size: clamp(1.35rem, 2.4vw, 2rem);
+  line-height: 1.12;
+}
+
+.preview-header .download-subtitle {
+  margin: 0.45rem 0 0;
+}
+
+.preview-window {
+  overflow: hidden;
+  border: 1px solid color-mix(in srgb, var(--border) 78%, var(--primary));
+  border-radius: var(--radius);
+  background:
+    linear-gradient(180deg, color-mix(in srgb, var(--card) 94%, transparent), color-mix(in srgb, var(--background) 92%, transparent));
+  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.28);
+}
+
+.preview-window-titlebar {
+  min-height: 3rem;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+  padding: 0.72rem 0.9rem;
+  border-bottom: 1px solid var(--border);
+  background: color-mix(in srgb, var(--muted) 62%, transparent);
+}
+
+.preview-window-titlebar > div:first-child {
+  min-width: 0;
+  display: flex;
+  align-items: baseline;
+  gap: 0.6rem;
+}
+
+.preview-window-titlebar strong {
+  font-size: 0.92rem;
+}
+
+.preview-window-titlebar span {
+  overflow: hidden;
+  color: var(--muted-foreground);
+  font-size: 0.78rem;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.preview-window-tools {
+  display: inline-flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 0.35rem;
+}
+
+.preview-fullscreen-button {
+  appearance: none;
+  min-height: 2rem;
+  padding: 0.35rem 0.7rem;
+  border: 1px solid color-mix(in srgb, var(--border) 82%, var(--primary));
+  border-radius: calc(var(--radius) - 0.35rem);
+  background: color-mix(in srgb, var(--muted) 74%, transparent);
+  color: var(--foreground);
+  font: inherit;
+  font-size: 0.78rem;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.preview-fullscreen-button:hover {
+  background: color-mix(in srgb, var(--primary) 18%, var(--muted));
+}
+
+.preview-fullscreen-button[hidden] {
+  display: none !important;
+}
+
+.preview-window-actions {
+  display: inline-flex;
+  gap: 0.35rem;
+}
+
+.preview-window-actions span {
+  width: 0.72rem;
+  height: 0.72rem;
+  border: 1px solid color-mix(in srgb, var(--border) 75%, var(--foreground));
+  border-radius: 999px;
+  background: var(--muted);
+}
+
+.preview-tabs {
+  display: flex;
+  gap: 0.35rem;
+  padding: 0.55rem 0.7rem;
+  border-bottom: 1px solid var(--border);
+  background: color-mix(in srgb, var(--card) 78%, transparent);
+}
+
+.preview-tabs[hidden] {
+  display: none !important;
+}
+
+.preview-tab {
+  appearance: none;
+  min-height: 2rem;
+  padding: 0.35rem 0.7rem;
+  border: 1px solid transparent;
+  border-radius: calc(var(--radius) - 0.35rem);
+  background: transparent;
+  color: var(--muted-foreground);
+  font: inherit;
+  font-size: 0.8rem;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.preview-tab:hover,
+.preview-tab.is-active {
+  border-color: color-mix(in srgb, var(--border) 82%, var(--primary));
+  background: color-mix(in srgb, var(--muted) 78%, transparent);
+  color: var(--foreground);
+}
+
+.preview-stage {
+  overflow: hidden;
+  min-height: clamp(18rem, 64vh, 38rem);
+  display: grid;
+  place-items: center;
+  background:
+    linear-gradient(45deg, color-mix(in srgb, var(--muted) 18%, transparent) 25%, transparent 25%),
+    linear-gradient(-45deg, color-mix(in srgb, var(--muted) 18%, transparent) 25%, transparent 25%),
+    color-mix(in srgb, var(--background) 88%, #000);
+  background-position: 0 0, 0.5rem 0.5rem;
+  background-size: 1rem 1rem;
+}
+
+.preview-stage > * {
+  grid-area: 1 / 1;
+}
+
+.preview-stage > img,
+.preview-stage > video {
+  max-height: clamp(18rem, 64vh, 38rem);
+  width: 100%;
+  object-fit: contain;
+}
+
+.preview-stage > audio {
+  width: min(42rem, calc(100% - 2rem));
+}
+
+.default-preview,
+.large-preview-gate {
+  width: min(26rem, calc(100% - 2rem));
+  display: grid;
+  place-items: center;
+  gap: 0.9rem;
+  padding: 2rem;
+  color: var(--muted-foreground);
+  text-align: center;
+}
+
+.default-preview img {
+  width: 5.5rem;
+  height: 5.5rem;
+  object-fit: contain;
+}
+
+.default-preview div {
+  min-width: 0;
+  display: grid;
+  gap: 0.25rem;
+}
+
+.default-preview strong {
+  max-width: 100%;
+  overflow: hidden;
+  color: var(--foreground);
+  font-size: 1rem;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.default-preview span {
+  font-size: 0.86rem;
+}
+
+.large-preview-gate {
+  border: 1px solid color-mix(in srgb, var(--border) 82%, var(--danger));
+  border-radius: var(--radius);
+  background: color-mix(in srgb, var(--card) 92%, #000);
+}
+
+.large-preview-gate strong {
+  color: var(--foreground);
+  font-size: 1rem;
+}
+
+.large-preview-gate p {
+  margin: 0;
+  line-height: 1.45;
+}
+
+.large-preview-gate div {
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: center;
+  gap: 0.5rem;
+}
+
+.native-preview {
+  width: 100%;
+  height: clamp(18rem, 64vh, 38rem);
+}
+
+.video-scenes-preview {
+  object-fit: contain;
+  background: color-mix(in srgb, var(--background) 88%, black 12%);
+}
+
+.native-audio-preview {
+  align-self: center;
+  width: min(42rem, calc(100% - 2rem));
+  height: auto;
+}
+
+.preview-placeholder {
+  display: grid;
+  place-items: center;
+  gap: 0.8rem;
+  padding: 2rem;
+  color: var(--muted-foreground);
+  text-align: center;
+}
+
+.preview-placeholder[hidden],
+.default-preview[hidden],
+.native-preview[hidden],
+.large-preview-gate[hidden],
+.code-preview[hidden],
+.render-preview[hidden] {
+  display: none !important;
+}
+
+.preview-placeholder img {
+  width: 5rem;
+  height: 5rem;
+  object-fit: contain;
+  opacity: 0.78;
+}
+
+.preview-placeholder p {
+  margin: 0;
+  font-size: 0.9rem;
+}
+
+.code-preview {
+  min-width: 0;
+  width: 100%;
+  height: clamp(18rem, 64vh, 38rem);
+  overflow: auto;
+  background: #1b1724;
+}
+
+.code-preview pre[class*="language-"] {
+  width: max-content;
+  min-width: 100%;
+  min-height: 100%;
+  margin: 0;
+  border: 0;
+  border-radius: 0;
+  box-shadow: none;
+  background: transparent;
+  font-size: 0.88rem;
+  line-height: 1.55;
+  overflow: visible;
+  text-shadow: none;
+}
+
+.code-preview pre {
+  width: max-content;
+  min-width: 100%;
+  min-height: 100%;
+  margin: 0;
+  padding: 1rem;
+  overflow: visible;
+  color: #f5f3ff;
+  font-family: Consolas, Monaco, "Andale Mono", "Ubuntu Mono", monospace;
+  font-size: 0.88rem;
+  line-height: 1.55;
+  white-space: pre;
+}
+
+.code-preview pre[class*="language-"] > code {
+  white-space: pre;
+}
+
+.code-preview code[class*="language-"] {
+  text-shadow: none;
+}
+
+.code-preview .token.punctuation {
+  opacity: 0.9;
+}
+
+.render-preview {
+  width: 100%;
+  height: clamp(18rem, 64vh, 38rem);
+  border: 0;
+  background: var(--background);
+}
+
+.preview-window:fullscreen,
+.preview-window.is-render-fullscreen {
+  width: 100dvw;
+  height: 100dvh;
+  max-width: none;
+  display: grid;
+  grid-template-rows: auto auto minmax(0, 1fr);
+  border: 0;
+  border-radius: 0;
+  background: var(--background);
+}
+
+.preview-window.is-render-fullscreen {
+  position: fixed;
+  inset: 0;
+  z-index: 1000;
+}
+
+.preview-window:fullscreen .preview-stage,
+.preview-window.is-render-fullscreen .preview-stage {
+  min-height: 0;
+  height: 100%;
+  place-items: stretch;
+}
+
+.preview-window:fullscreen .render-preview,
+.preview-window.is-render-fullscreen .render-preview {
+  width: 100%;
+  height: 100%;
+}
+
 .file-emblem {
   width: 4rem;
   height: 4rem;
@@ -801,23 +1174,36 @@ html.reaction-picker-open body {
   text-align: right;
 }
 
-.preview-stage {
-  overflow: hidden;
-  margin-bottom: 1rem;
-  border: 1px solid var(--border);
-  border-radius: var(--radius);
-  background: var(--background);
+@media (max-width: 720px) {
+  .preview-view {
+    width: min(100%, calc(100% - 1rem));
+    padding-block: 1rem;
   }
 
-.preview-stage img,
-.preview-stage video {
-  width: 100%;
-  max-height: 55vh;
-  display: block;
-  object-fit: contain;
+  .preview-header {
+    flex-direction: column;
+    align-items: stretch;
   }
 
-.preview-stage audio {
-  width: calc(100% - 2rem);
-  margin: 1rem;
+  .preview-header .button {
+    justify-content: center;
+  }
+
+  .preview-window-titlebar > div:first-child {
+    display: grid;
+    gap: 0.2rem;
+  }
+
+  .preview-stage,
+  .code-preview,
+  .render-preview,
+  .native-preview {
+    min-height: 18rem;
+    height: min(60vh, 32rem);
+  }
+
+  .preview-stage > img,
+  .preview-stage > video {
+    max-height: min(60vh, 32rem);
+  }
 }

backend/static/css/80-markdown-preview.css

@@ -0,0 +1,299 @@
+:root {
+  color-scheme: dark;
+  --md-bg: #0b0b16;
+  --md-fg: #f5f3ff;
+  --md-muted: #aaa4d6;
+  --md-panel: #17142d;
+  --md-panel-2: #211b3e;
+  --md-border: rgba(168, 150, 255, 0.24);
+  --md-link: #67e8f9;
+  --md-accent: #a78bfa;
+  --md-code-bg: #1b1724;
+  --md-block-code-bg: #0f111a;
+  --md-block-code-fg: #f8fafc;
+  --md-block-code-border: rgba(248, 250, 252, 0.16);
+  --md-shadow: rgba(0, 0, 0, 0.28);
+  --md-font: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+  --md-mono: Consolas, Monaco, "Andale Mono", "Ubuntu Mono", monospace;
+}
+
+:root[data-theme="classic"] {
+  --md-bg: #09090b;
+  --md-fg: #fafafa;
+  --md-muted: #a1a1aa;
+  --md-panel: #18181b;
+  --md-panel-2: #27272a;
+  --md-border: rgba(255, 255, 255, 0.13);
+  --md-link: #e4e4e7;
+  --md-accent: #d4d4d8;
+  --md-code-bg: #111113;
+  --md-block-code-bg: #09090b;
+  --md-block-code-fg: #fafafa;
+  --md-block-code-border: rgba(250, 250, 250, 0.15);
+  --md-shadow: rgba(0, 0, 0, 0.3);
+}
+
+:root[data-theme="retro"] {
+  color-scheme: light;
+  --md-bg: #c0c0c0;
+  --md-fg: #000000;
+  --md-muted: #404040;
+  --md-panel: #ffffff;
+  --md-panel-2: #dfdfdf;
+  --md-border: #000000;
+  --md-link: #000078;
+  --md-accent: #000078;
+  --md-code-bg: #ffffff;
+  --md-block-code-bg: #000000;
+  --md-block-code-fg: #f5f5f5;
+  --md-block-code-border: #808080;
+  --md-shadow: transparent;
+  --md-font: "PixeloidSans", "PixelOperator", "Microsoft Sans Serif", Tahoma, sans-serif;
+  --md-mono: "PixelOperatorMono", Consolas, monospace;
+}
+
+:root[data-theme="gruvbox"] {
+  --md-bg: #1d2021;
+  --md-fg: #ebdbb2;
+  --md-muted: #bdae93;
+  --md-panel: #282828;
+  --md-panel-2: #32302f;
+  --md-border: rgba(235, 219, 178, 0.2);
+  --md-link: #fabd2f;
+  --md-accent: #d79921;
+  --md-code-bg: #1b1d1e;
+  --md-block-code-bg: #161819;
+  --md-block-code-fg: #fbf1c7;
+  --md-block-code-border: rgba(251, 241, 199, 0.18);
+  --md-shadow: rgba(0, 0, 0, 0.26);
+}
+
+:root[data-theme="cyberpunk"] {
+  --md-bg: #08070d;
+  --md-fg: #fff36f;
+  --md-muted: #9bfaff;
+  --md-panel: #16131f;
+  --md-panel-2: #251d34;
+  --md-border: rgba(255, 242, 0, 0.34);
+  --md-link: #00f0ff;
+  --md-accent: #ff2a6d;
+  --md-code-bg: #100d18;
+  --md-block-code-bg: #07060b;
+  --md-block-code-fg: #f8fafc;
+  --md-block-code-border: rgba(0, 240, 255, 0.26);
+  --md-shadow: rgba(255, 42, 109, 0.14);
+}
+
+@font-face {
+  font-family: "PixeloidSans";
+  src: url("/static/fonts/pixeloid_sans/PixeloidSans.ttf") format("truetype");
+  font-weight: normal;
+  font-display: swap;
+}
+
+@font-face {
+  font-family: "PixeloidSans";
+  src: url("/static/fonts/pixeloid_sans/PixeloidSans-Bold.ttf") format("truetype");
+  font-weight: bold;
+  font-display: swap;
+}
+
+@font-face {
+  font-family: "PixelOperatorMono";
+  src: url("/static/fonts/pixel_operator/PixelOperatorMono.ttf") format("truetype");
+  font-weight: normal;
+  font-display: swap;
+}
+
+* {
+  box-sizing: border-box;
+}
+
+html {
+  min-height: 100%;
+  background:
+    radial-gradient(circle at 18% -10%, color-mix(in srgb, var(--md-accent) 18%, transparent), transparent 24rem),
+    var(--md-bg);
+  color: var(--md-fg);
+  font-family: var(--md-font);
+}
+
+html[data-theme="retro"] {
+  background-color: #000000;
+  background-image: url("/static/backgrounds/stars1.gif");
+  background-repeat: repeat;
+  image-rendering: pixelated;
+}
+
+html[data-theme="cyberpunk"] {
+  background:
+    linear-gradient(rgba(255, 242, 0, 0.035) 1px, transparent 1px),
+    linear-gradient(90deg, rgba(0, 240, 255, 0.03) 1px, transparent 1px),
+    var(--md-bg);
+  background-size: 100% 3px, 3rem 100%, auto;
+}
+
+body {
+  min-height: 100vh;
+  margin: 0;
+  padding: clamp(1rem, 4vw, 2.25rem);
+  font-size: 16px;
+  line-height: 1.65;
+}
+
+main {
+  max-width: 54rem;
+  margin: 0 auto;
+  padding: clamp(1rem, 3vw, 2rem);
+  border: 1px solid var(--md-border);
+  border-radius: 10px;
+  background: color-mix(in srgb, var(--md-panel) 90%, transparent);
+  box-shadow: 0 20px 60px var(--md-shadow);
+}
+
+html[data-theme="retro"] main {
+  border-radius: 0;
+  background: var(--md-panel);
+  box-shadow:
+    inset -1px -1px 0 #404040,
+    inset 1px 1px 0 #ffffff,
+    inset -2px -2px 0 #808080,
+    inset 2px 2px 0 #dfdfdf;
+}
+
+html[data-theme="cyberpunk"] main {
+  border-radius: 0;
+  box-shadow: 4px 4px 0 rgba(255, 42, 109, 0.5), 0 0 24px rgba(0, 240, 255, 0.12);
+  clip-path: polygon(0 0, calc(100% - 0.9rem) 0, 100% 0.9rem, 100% 100%, 0.9rem 100%, 0 calc(100% - 0.9rem));
+}
+
+h1,
+h2,
+h3,
+h4,
+h5,
+h6 {
+  margin: 1.4em 0 0.55em;
+  color: var(--md-fg);
+  line-height: 1.2;
+}
+
+h1:first-child,
+h2:first-child,
+h3:first-child {
+  margin-top: 0;
+}
+
+h1 {
+  font-size: clamp(1.75rem, 5vw, 2.45rem);
+}
+
+h2 {
+  padding-bottom: 0.35rem;
+  border-bottom: 1px solid var(--md-border);
+  font-size: 1.45rem;
+}
+
+p,
+ul,
+ol,
+blockquote,
+pre,
+table {
+  margin: 0 0 1rem;
+}
+
+a {
+  color: var(--md-link);
+  text-underline-offset: 0.18em;
+}
+
+a:hover {
+  color: var(--md-accent);
+}
+
+img,
+video {
+  max-width: 100%;
+  height: auto;
+  border-radius: 8px;
+}
+
+html[data-theme="retro"] img,
+html[data-theme="retro"] video {
+  border-radius: 0;
+  image-rendering: pixelated;
+}
+
+hr {
+  height: 1px;
+  border: 0;
+  background: var(--md-border);
+}
+
+blockquote {
+  margin-left: 0;
+  padding: 0.75rem 1rem;
+  border-left: 4px solid var(--md-accent);
+  background: color-mix(in srgb, var(--md-panel-2) 58%, transparent);
+  color: var(--md-muted);
+}
+
+pre {
+  overflow: auto;
+  padding: 1rem;
+  border: 1px solid var(--md-block-code-border) !important;
+  border-radius: 8px;
+  background: var(--md-block-code-bg) !important;
+  color: var(--md-block-code-fg) !important;
+}
+
+code {
+  font-family: var(--md-mono);
+}
+
+pre code,
+pre > code,
+pre code[class*="language-"] {
+  padding: 0 !important;
+  border: 0 !important;
+  background: transparent !important;
+  color: inherit !important;
+}
+
+:not(pre) > code {
+  padding: 0.12rem 0.28rem;
+  border: 1px solid var(--md-border);
+  border-radius: 0.25rem;
+  background: color-mix(in srgb, var(--md-code-bg) 82%, transparent);
+}
+
+html[data-theme="retro"] pre,
+html[data-theme="retro"] :not(pre) > code {
+  border-radius: 0;
+}
+
+table {
+  width: 100%;
+  border-collapse: collapse;
+}
+
+th,
+td {
+  padding: 0.5rem 0.65rem;
+  border: 1px solid var(--md-border);
+}
+
+th {
+  background: color-mix(in srgb, var(--md-panel-2) 70%, transparent);
+  color: var(--md-fg);
+}
+
+tr:nth-child(even) td {
+  background: color-mix(in srgb, var(--md-panel-2) 28%, transparent);
+}
+
+::selection {
+  background: var(--md-accent);
+  color: var(--md-bg);
+}

backend/static/humans.txt

@@ -0,0 +1,6 @@
+/* TEAM */
+Built by: Danlegt
+
+/* SITE */
+Language: English
+Software: Warp Box

backend/static/js/40-upload.js

@@ -117,9 +117,7 @@
         uploadQueue.hidden = true;
         uploadQueue.replaceChildren();
       }
-      if (newUpload) {
-        newUpload.hidden = true;
-      }
+      updateNewUploadVisibility();
       if (fileSummary) {
         fileSummary.textContent = "Upload complete.";
       }
@@ -189,9 +187,16 @@
       uploadQueue.hidden = true;
       uploadQueue.replaceChildren();
     }
-    if (newUpload) {
-      newUpload.hidden = !(resumeMode && recoveredDraft);
+    updateNewUploadVisibility();
   }
+
+  function updateNewUploadVisibility() {
+    if (!newUpload) {
+      return;
+    }
+    const visible = Boolean(resumeMode && recoveredDraft);
+    newUpload.hidden = !visible;
+    newUpload.style.display = visible ? "" : "none";
   }
 
   function setLoading(isLoading, submit) {
@@ -216,6 +221,41 @@
     }
   }
 
+  function updateUploadProgress(percent, bytesPerSecond) {
+    const clamped = Math.max(0, Math.min(100, Math.round(percent || 0)));
+    const rate = formatTransferRate(bytesPerSecond);
+    updateStatus(rate ? `${clamped}% · ${rate}` : `${clamped}%`);
+  }
+
+  function createTransferRateTracker(initialBytes) {
+    const startedAt = performance.now();
+    const baseline = Math.max(0, initialBytes || 0);
+    let lastRate = 0;
+    return function track(currentBytes) {
+      const elapsedSeconds = (performance.now() - startedAt) / 1000;
+      const transferred = Math.max(0, (currentBytes || 0) - baseline);
+      if (elapsedSeconds < 0.25 || transferred <= 0) {
+        return lastRate;
+      }
+      lastRate = transferred / elapsedSeconds;
+      return lastRate;
+    };
+  }
+
+  function formatTransferRate(bytesPerSecond) {
+    if (!Number.isFinite(bytesPerSecond) || bytesPerSecond <= 0) {
+      return "";
+    }
+    const units = ["b/s", "Kb/s", "Mb/s", "Gb/s"];
+    let value = bytesPerSecond * 8;
+    let unit = 0;
+    while (value >= 1000 && unit < units.length - 1) {
+      value /= 1000;
+      unit += 1;
+    }
+    return `${value >= 10 || unit === 0 ? value.toFixed(0) : value.toFixed(1)} ${units[unit]}`;
+  }
+
   function renderResult(payload) {
     if (!result || !resultList || !resultMeta || !openBox) {
       return;
@@ -248,16 +288,18 @@
   function uploadWithProgress(url, formData, files) {
     return new Promise((resolve, reject) => {
       const request = new XMLHttpRequest();
+      const rateTracker = createTransferRateTracker(0);
       request.open("POST", url);
       request.setRequestHeader("Accept", "application/json");
 
       request.upload.addEventListener("progress", (event) => {
+        const rate = rateTracker(event.loaded || 0);
         if (!event.lengthComputable) {
-          updateStatus("Uploading...");
+          updateStatus(rate > 0 ? `Uploading · ${formatTransferRate(rate)}` : "Uploading...");
           return;
         }
         const percent = Math.round((event.loaded / event.total) * 100);
-        updateStatus(`${percent}%`);
+        updateUploadProgress(percent, rate);
         setTotalProgress(percent);
         setFileProgress(files, percent);
       });
@@ -348,7 +390,9 @@
       completedByFile[index] = uploadedBytesForSessionFile(sessionFile, session.chunkSize);
       setSingleFileProgress(index, files[index], percentForBytes(completedByFile[index], files[index].size));
     });
-    setTotalProgress(percentForBytes(completedByFile.reduce((sum, bytes) => sum + bytes, 0), totalBytes));
+    const initiallyUploadedBytes = completedByFile.reduce((sum, bytes) => sum + bytes, 0);
+    const rateTracker = createTransferRateTracker(initiallyUploadedBytes);
+    setTotalProgress(percentForBytes(initiallyUploadedBytes, totalBytes));
 
     for (let fileIndex = 0; fileIndex < files.length; fileIndex++) {
       const file = files[fileIndex];
@@ -362,9 +406,11 @@
         const end = Math.min(file.size, start + session.chunkSize);
         await uploadChunkWithRetry(session, sessionFile, chunkIndex, file.slice(start, end), (loaded) => {
           const currentTotal = completedByFile.reduce((sum, bytes) => sum + bytes, 0) + loaded;
-          setTotalProgress(percentForBytes(currentTotal, totalBytes));
+          const percent = percentForBytes(currentTotal, totalBytes);
+          const rate = rateTracker(currentTotal);
+          setTotalProgress(percent);
           setSingleFileProgress(fileIndex, file, percentForBytes(completedByFile[fileIndex] + loaded, file.size));
-          updateStatus(`${percentForBytes(currentTotal, totalBytes)}%`);
+          updateUploadProgress(percent, rate);
         });
         completedByFile[fileIndex] += end - start;
         uploaded.add(chunkIndex);
@@ -749,6 +795,7 @@
     selectedFiles = [];
     renderResumeQueue(recoveredDraft.session, selectedFiles);
     updateSelectedState();
+    updateNewUploadVisibility();
     updateStatus("Drop or reselect missing files to continue. Extra files will be added to this upload.");
   }
 

backend/static/js/45-preview.js

@@ -0,0 +1,739 @@
+(function () {
+  var preview = document.querySelector("[data-source-url][data-file-name][data-content-type]");
+  if (!preview) {
+    return;
+  }
+
+  var SMALL_TEXT_BYTES = 50 * 1024;
+  var LARGE_PREVIEW_BYTES = 500 * 1024;
+
+  var state = {
+    fileName: preview.dataset.fileName || "",
+    contentType: (preview.dataset.contentType || "").toLowerCase(),
+    previewKind: preview.dataset.previewKind || "",
+    sizeBytes: Number(preview.dataset.sizeBytes || 0),
+    sizeLabel: preview.dataset.fileSize || "",
+    sourceURL: preview.dataset.sourceUrl || "",
+    downloadURL: preview.dataset.downloadUrl || "",
+    iconURL: preview.dataset.iconUrl || "",
+    sceneURL: preview.dataset.sceneUrl || "",
+    activeMode: "",
+    defaultMode: "default",
+    pendingMode: "",
+    textSource: "",
+    textLoaded: false,
+    rawLoaded: false,
+    prismLoaded: false,
+    renderLoaded: false,
+    sceneLoaded: false,
+    renderFullscreenFallback: false,
+    confirmedLargeModes: {},
+    tabs: []
+  };
+
+  var els = {
+    tabs: preview.querySelector("[data-preview-tabs]"),
+    modeLabel: preview.querySelector("[data-preview-mode-label]"),
+    defaultPane: preview.querySelector("[data-default-preview]"),
+    imagePane: preview.querySelector("[data-image-preview]"),
+    videoPane: preview.querySelector("[data-video-preview]"),
+    videoScenesPane: preview.querySelector("[data-video-scenes-preview]"),
+    browserAudioPane: preview.querySelector("[data-browser-audio-preview]"),
+    rawPane: preview.querySelector("[data-raw-preview]"),
+    rawOutput: preview.querySelector("[data-raw-output]"),
+    codePane: preview.querySelector("[data-code-preview]"),
+    codeOutput: preview.querySelector("[data-code-output]"),
+    renderPane: preview.querySelector("[data-render-preview]"),
+    fullscreenButton: preview.querySelector("[data-render-fullscreen]"),
+    gatePane: preview.querySelector("[data-large-preview-gate]"),
+    gateConfirm: preview.querySelector("[data-large-preview-confirm]"),
+    gateCancel: preview.querySelector("[data-large-preview-cancel]"),
+    placeholder: preview.querySelector("[data-preview-placeholder]")
+  };
+
+  var fileType = detectFileType();
+  state.tabs = buildTabs(fileType);
+  state.defaultMode = chooseDefaultMode(fileType, state.tabs);
+
+  bindLargeGate();
+  bindThemeChanges();
+  bindRenderFullscreen();
+  renderTabs();
+  selectMode(state.defaultMode);
+
+  function detectFileType() {
+    var extension = extensionFor(state.fileName);
+    var baseType = state.contentType.split(";")[0].trim();
+    var language = languageFor(extension, baseType);
+    var isImage = state.previewKind === "image" || baseType.indexOf("image/") === 0 && baseType !== "image/svg+xml";
+    var isVideo = state.previewKind === "video" || baseType.indexOf("video/") === 0;
+    var isAudio = state.previewKind === "audio" || baseType.indexOf("audio/") === 0;
+
+    return {
+      extension: extension,
+      baseType: baseType,
+      language: language,
+      isTextLike: Boolean(language),
+      isHTML: language === "html",
+      isMarkdown: language === "markdown",
+      isImage: isImage,
+      isVideo: isVideo,
+      isAudio: isAudio,
+      isMobile: window.matchMedia && window.matchMedia("(max-width: 720px), (pointer: coarse)").matches
+    };
+  }
+
+  function buildTabs(type) {
+    var tabs = [{ mode: "default", label: "Default" }];
+
+    if (type.isImage) {
+      tabs.push({ mode: "image", label: "Image Preview" });
+      return tabs;
+    }
+
+    if (type.isVideo) {
+      tabs.push({ mode: "video", label: "Video Preview" });
+      if (state.sceneURL && els.videoScenesPane) {
+        tabs.push({ mode: "scenes", label: "Scenes Preview" });
+      }
+      return tabs;
+    }
+
+    if (type.isAudio) {
+      tabs.push({ mode: "browser-audio", label: "Browser Preview" });
+      return tabs;
+    }
+
+    if (type.isTextLike) {
+      if (type.isHTML || type.isMarkdown) {
+        tabs.push({ mode: "render", label: "Render Preview" });
+      }
+      tabs.push({ mode: "raw", label: "Raw Preview" });
+      tabs.push({ mode: "code", label: "Code Preview" });
+    }
+
+    return tabs;
+  }
+
+  function chooseDefaultMode(type, tabs) {
+    if (type.isImage) {
+      return "image";
+    }
+    if (type.isVideo) {
+      return "video";
+    }
+    if (state.sizeBytes > LARGE_PREVIEW_BYTES) {
+      if (type.isAudio && hasMode(tabs, "browser-audio")) {
+        return "browser-audio";
+      }
+      return "default";
+    }
+    if (type.isAudio) {
+      return "browser-audio";
+    }
+    if (type.isTextLike && state.sizeBytes > SMALL_TEXT_BYTES) {
+      return "raw";
+    }
+    if (type.isMarkdown) {
+      return "render";
+    }
+    if (type.isTextLike) {
+      return "code";
+    }
+    return "default";
+  }
+
+  function renderTabs() {
+    if (!els.tabs) {
+      return;
+    }
+    els.tabs.innerHTML = "";
+    state.tabs.forEach(function (tab) {
+      var button = document.createElement("button");
+      button.className = "preview-tab";
+      button.type = "button";
+      button.dataset.previewTab = tab.mode;
+      button.textContent = tab.label;
+      button.addEventListener("click", function () {
+        selectMode(tab.mode);
+      });
+      els.tabs.appendChild(button);
+    });
+  }
+
+  function selectMode(mode) {
+    if (!hasMode(state.tabs, mode)) {
+      mode = "default";
+    }
+
+    if (mode !== "render") {
+      exitRenderFullscreen();
+    }
+
+    if (requiresLargeConfirmation(mode)) {
+      showLargeGate(mode);
+      return;
+    }
+
+    state.activeMode = mode;
+    updateTabs(mode);
+    updateRenderFullscreenButton();
+    hideAllPanes();
+    setModeLabel(labelForMode(mode));
+
+    if (mode === "default") {
+      show(els.defaultPane);
+    } else if (mode === "image") {
+      show(els.imagePane);
+    } else if (mode === "video") {
+      show(els.videoPane);
+    } else if (mode === "scenes") {
+      show(els.videoScenesPane);
+      ensureScenesPreview();
+    } else if (mode === "browser-audio") {
+      show(els.browserAudioPane);
+    } else if (mode === "raw") {
+      show(els.rawPane);
+      ensureRawPreview();
+    } else if (mode === "code") {
+      show(els.codePane);
+      ensurePrismPreview();
+    } else if (mode === "render") {
+      show(els.renderPane);
+      if (fileType.isMarkdown) {
+        ensureMarkdownRenderPreview();
+      } else {
+        ensureHTMLRenderPreview();
+      }
+    }
+  }
+
+  function requiresLargeConfirmation(mode) {
+    if (state.sizeBytes <= LARGE_PREVIEW_BYTES || state.confirmedLargeModes[mode]) {
+      return false;
+    }
+    return mode === "raw" || mode === "code" || mode === "render";
+  }
+
+  function showLargeGate(mode) {
+    state.pendingMode = mode;
+    updateTabs(state.activeMode || state.defaultMode);
+    updateRenderFullscreenButton(false);
+    hideAllPanes();
+    show(els.gatePane);
+    setModeLabel("Large preview");
+  }
+
+  function bindLargeGate() {
+    if (els.gateConfirm) {
+      els.gateConfirm.addEventListener("click", function () {
+        if (!state.pendingMode) {
+          return;
+        }
+        state.confirmedLargeModes[state.pendingMode] = true;
+        selectMode(state.pendingMode);
+      });
+    }
+    if (els.gateCancel) {
+      els.gateCancel.addEventListener("click", function () {
+        state.pendingMode = "";
+        selectMode(state.activeMode || state.defaultMode || "default");
+      });
+    }
+  }
+
+  function bindThemeChanges() {
+    var themeSelect = document.querySelector("[data-theme-select]");
+    if (!themeSelect) {
+      return;
+    }
+    themeSelect.addEventListener("change", function () {
+      window.setTimeout(function () {
+        if (!fileType.isMarkdown || !state.renderLoaded) {
+          return;
+        }
+        state.renderLoaded = false;
+        if (state.activeMode === "render") {
+          ensureMarkdownRenderPreview();
+        }
+      }, 0);
+    });
+  }
+
+  function bindRenderFullscreen() {
+    if (!els.fullscreenButton) {
+      return;
+    }
+
+    els.fullscreenButton.addEventListener("click", function () {
+      if (isRenderFullscreen()) {
+        exitRenderFullscreen();
+        return;
+      }
+      enterRenderFullscreen();
+    });
+
+    document.addEventListener("fullscreenchange", updateRenderFullscreenButton);
+  }
+
+  function ensureTextLoaded() {
+    if (state.textLoaded) {
+      return Promise.resolve(state.textSource);
+    }
+
+    showLoading("Loading preview...");
+    return fetch(state.sourceURL, { credentials: "same-origin" })
+      .then(function (response) {
+        if (!response.ok) {
+          throw new Error("Preview failed");
+        }
+        return response.text();
+      })
+      .then(function (source) {
+        state.textSource = source;
+        state.textLoaded = true;
+        hide(els.placeholder);
+        return source;
+      })
+      .catch(function (error) {
+        showError("Preview unavailable");
+        throw error;
+      });
+  }
+
+  function ensureRawPreview() {
+    if (state.rawLoaded) {
+      return;
+    }
+
+    ensureTextLoaded().then(function (source) {
+      els.rawOutput.textContent = source;
+      state.rawLoaded = true;
+      if (state.activeMode === "raw") {
+        hide(els.placeholder);
+        show(els.rawPane);
+      }
+    });
+  }
+
+  function ensurePrismPreview() {
+    if (state.prismLoaded) {
+      return;
+    }
+
+    showLoading("Loading syntax preview...");
+    Promise.all([ensureTextLoaded(), loadPrism()])
+      .then(function (results) {
+        var source = results[0];
+        var language = fileType.language;
+        if (language === "json") {
+          source = formatJSON(source);
+        }
+        els.codeOutput.className = "language-" + language;
+        els.codeOutput.textContent = source;
+        if (window.Prism) {
+          window.Prism.highlightElement(els.codeOutput);
+        }
+        state.prismLoaded = true;
+        if (state.activeMode === "code") {
+          hide(els.placeholder);
+          show(els.codePane);
+        }
+      })
+      .catch(function () {
+        showError("Syntax preview unavailable");
+      });
+  }
+
+  function ensureHTMLRenderPreview() {
+    if (state.renderLoaded) {
+      return;
+    }
+
+    showLoading("Rendering preview...");
+    ensureTextLoaded()
+      .then(function (source) {
+        els.renderPane.srcdoc = withBaseElement(source);
+        state.renderLoaded = true;
+        if (state.activeMode === "render") {
+          hide(els.placeholder);
+          show(els.renderPane);
+        }
+      })
+      .catch(function () {
+        showError("Render preview unavailable");
+      });
+  }
+
+  function ensureMarkdownRenderPreview() {
+    if (state.renderLoaded) {
+      return;
+    }
+
+    showLoading("Rendering Markdown...");
+    Promise.all([ensureTextLoaded(), loadMarkdownLibs()])
+      .then(function (results) {
+        var markdown = results[0];
+        var html = parseMarkdown(markdown);
+        var clean = window.DOMPurify.sanitize(html);
+        els.renderPane.srcdoc = markdownDocument(clean);
+        state.renderLoaded = true;
+        if (state.activeMode === "render") {
+          hide(els.placeholder);
+          show(els.renderPane);
+        }
+      })
+      .catch(function () {
+        showError("Markdown preview unavailable");
+      });
+  }
+
+  function showLoading(message) {
+    if (!els.placeholder) {
+      return;
+    }
+    var text = els.placeholder.querySelector("p");
+    if (text) {
+      text.textContent = message;
+    }
+    show(els.placeholder);
+  }
+
+  function showError(message) {
+    hideAllPanes();
+    var text = els.placeholder && els.placeholder.querySelector("p");
+    if (text) {
+      text.textContent = message;
+    }
+    show(els.placeholder);
+  }
+
+  function hideAllPanes() {
+    hide(els.defaultPane);
+    hide(els.imagePane);
+    hide(els.videoPane);
+    hide(els.videoScenesPane);
+    hide(els.browserAudioPane);
+    hide(els.rawPane);
+    hide(els.codePane);
+    hide(els.renderPane);
+    hide(els.gatePane);
+    hide(els.placeholder);
+  }
+
+  function enterRenderFullscreen() {
+    if (state.activeMode !== "render") {
+      return;
+    }
+
+    if (preview.requestFullscreen) {
+      var request = preview.requestFullscreen();
+      if (request && typeof request.catch === "function") {
+        request.catch(function () {
+          state.renderFullscreenFallback = true;
+          preview.classList.add("is-render-fullscreen");
+          updateRenderFullscreenButton();
+        });
+      }
+      return;
+    }
+
+    state.renderFullscreenFallback = true;
+    preview.classList.add("is-render-fullscreen");
+    updateRenderFullscreenButton();
+  }
+
+  function exitRenderFullscreen() {
+    if (document.fullscreenElement === preview && document.exitFullscreen) {
+      var exit = document.exitFullscreen();
+      if (exit && typeof exit.catch === "function") {
+        exit.catch(function () {});
+      }
+    }
+    state.renderFullscreenFallback = false;
+    preview.classList.remove("is-render-fullscreen");
+    updateRenderFullscreenButton();
+  }
+
+  function isRenderFullscreen() {
+    return document.fullscreenElement === preview || state.renderFullscreenFallback;
+  }
+
+  function updateRenderFullscreenButton(forceVisible) {
+    if (!els.fullscreenButton) {
+      return;
+    }
+
+    var visible = typeof forceVisible === "boolean" ? forceVisible : state.activeMode === "render";
+    els.fullscreenButton.hidden = !visible;
+    els.fullscreenButton.textContent = isRenderFullscreen() ? "Exit Full Screen" : "Full Screen";
+    els.fullscreenButton.setAttribute("aria-pressed", isRenderFullscreen() ? "true" : "false");
+  }
+
+  function updateTabs(mode) {
+    if (!els.tabs) {
+      return;
+    }
+    Array.prototype.forEach.call(els.tabs.querySelectorAll("[data-preview-tab]"), function (button) {
+      button.classList.toggle("is-active", button.dataset.previewTab === mode);
+    });
+  }
+
+  function show(element) {
+    if (element) {
+      element.hidden = false;
+    }
+  }
+
+  function hide(element) {
+    if (element) {
+      element.hidden = true;
+    }
+  }
+
+  function setModeLabel(label) {
+    if (els.modeLabel) {
+      els.modeLabel.textContent = label;
+    }
+  }
+
+  function hasMode(tabs, mode) {
+    return tabs.some(function (tab) {
+      return tab.mode === mode;
+    });
+  }
+
+  function labelForMode(mode) {
+    var labels = {
+      "default": "Default",
+      "image": "Image preview",
+      "video": "Video preview",
+      "scenes": "Scenes preview",
+      "browser-audio": "Browser preview",
+      "raw": "Raw preview",
+      "code": "Code preview",
+      "render": "Render preview"
+    };
+    return labels[mode] || "Preview";
+  }
+
+  function ensureScenesPreview() {
+    if (state.sceneLoaded || !els.videoScenesPane) {
+      return;
+    }
+    var src = els.videoScenesPane.dataset.sceneSrc || state.sceneURL;
+    if (!src) {
+      return;
+    }
+    els.videoScenesPane.src = src;
+    state.sceneLoaded = true;
+  }
+
+  function loadPrism() {
+    if (window.Prism) {
+      return Promise.resolve();
+    }
+
+    window.Prism = window.Prism || {};
+    window.Prism.manual = true;
+    return Promise.all([
+      loadStyle("/static/lib/prismjs/prism.css"),
+      loadScript("/static/lib/prismjs/prism.js")
+    ]);
+  }
+
+  function loadMarkdownLibs() {
+    if (window.marked && window.DOMPurify) {
+      return Promise.resolve();
+    }
+
+    return Promise.all([
+      loadScript("/static/lib/markdown/marked.umd.js"),
+      loadScript("/static/lib/markdown/purify.min.js")
+    ]);
+  }
+
+  function loadScript(src) {
+    return new Promise(function (resolve, reject) {
+      var existing = document.querySelector('script[src="' + src + '"]');
+      if (existing) {
+        if (existing.dataset.loaded === "true") {
+          resolve();
+          return;
+        }
+        existing.addEventListener("load", resolve, { once: true });
+        existing.addEventListener("error", reject, { once: true });
+        return;
+      }
+
+      var script = document.createElement("script");
+      script.async = true;
+      script.src = src;
+      script.addEventListener("load", function () {
+        script.dataset.loaded = "true";
+        resolve();
+      }, { once: true });
+      script.addEventListener("error", reject, { once: true });
+      document.head.appendChild(script);
+    });
+  }
+
+  function loadStyle(href) {
+    if (document.querySelector('link[href="' + href + '"]')) {
+      return Promise.resolve();
+    }
+    return new Promise(function (resolve, reject) {
+      var link = document.createElement("link");
+      link.rel = "stylesheet";
+      link.href = href;
+      link.addEventListener("load", resolve, { once: true });
+      link.addEventListener("error", reject, { once: true });
+      document.head.appendChild(link);
+    });
+  }
+
+  function parseMarkdown(source) {
+    if (window.marked && typeof window.marked.parse === "function") {
+      return window.marked.parse(source);
+    }
+    if (window.marked && window.marked.marked && typeof window.marked.marked.parse === "function") {
+      return window.marked.marked.parse(source);
+    }
+    throw new Error("Marked unavailable");
+  }
+
+  function markdownDocument(body) {
+    var theme = currentTheme();
+    var base = '<base href="' + escapeAttribute(new URL(state.sourceURL, window.location.href).href) + '">';
+    return '<!doctype html><html data-theme="' + escapeAttribute(theme) + '"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1">' +
+      base +
+      '<link rel="stylesheet" href="/static/css/80-markdown-preview.css">' +
+      '<style>' + markdownThemeStyle(theme) + '</style>' +
+      '</head><body><main>' + body + '</main></body></html>';
+  }
+
+  function markdownThemeStyle(theme) {
+    var themes = {
+      revamp: ["dark", "#0b0b16", "#f5f3ff", "#aaa4d6", "#17142d", "#211b3e", "rgba(168,150,255,0.24)", "#67e8f9", "#a78bfa", "#1b1724", "#0f111a", "#f8fafc", "rgba(248,250,252,0.16)", "rgba(0,0,0,0.28)", "Inter,system-ui,-apple-system,BlinkMacSystemFont,\"Segoe UI\",sans-serif", "Consolas,Monaco,\"Andale Mono\",\"Ubuntu Mono\",monospace"],
+      classic: ["dark", "#09090b", "#fafafa", "#a1a1aa", "#18181b", "#27272a", "rgba(255,255,255,0.13)", "#e4e4e7", "#d4d4d8", "#111113", "#09090b", "#fafafa", "rgba(250,250,250,0.15)", "rgba(0,0,0,0.3)", "Inter,system-ui,-apple-system,BlinkMacSystemFont,\"Segoe UI\",sans-serif", "Consolas,Monaco,\"Andale Mono\",\"Ubuntu Mono\",monospace"],
+      retro: ["light", "#c0c0c0", "#000000", "#404040", "#ffffff", "#dfdfdf", "#000000", "#000078", "#000078", "#ffffff", "#000000", "#f5f5f5", "#808080", "transparent", "\"PixeloidSans\",\"PixelOperator\",\"Microsoft Sans Serif\",Tahoma,sans-serif", "\"PixelOperatorMono\",Consolas,monospace"],
+      gruvbox: ["dark", "#1d2021", "#ebdbb2", "#bdae93", "#282828", "#32302f", "rgba(235,219,178,0.2)", "#fabd2f", "#d79921", "#1b1d1e", "#161819", "#fbf1c7", "rgba(251,241,199,0.18)", "rgba(0,0,0,0.26)", "Inter,system-ui,-apple-system,BlinkMacSystemFont,\"Segoe UI\",sans-serif", "Consolas,Monaco,\"Andale Mono\",\"Ubuntu Mono\",monospace"],
+      cyberpunk: ["dark", "#08070d", "#fff36f", "#9bfaff", "#16131f", "#251d34", "rgba(255,242,0,0.34)", "#00f0ff", "#ff2a6d", "#100d18", "#07060b", "#f8fafc", "rgba(0,240,255,0.26)", "rgba(255,42,109,0.14)", "Inter,system-ui,-apple-system,BlinkMacSystemFont,\"Segoe UI\",sans-serif", "Consolas,Monaco,\"Andale Mono\",\"Ubuntu Mono\",monospace"]
+    };
+    var t = themes[theme] || themes.revamp;
+    var vars = "color-scheme:" + t[0] + ";--md-bg:" + t[1] + ";--md-fg:" + t[2] + ";--md-muted:" + t[3] + ";--md-panel:" + t[4] + ";--md-panel-2:" + t[5] + ";--md-border:" + t[6] + ";--md-link:" + t[7] + ";--md-accent:" + t[8] + ";--md-code-bg:" + t[9] + ";--md-block-code-bg:" + t[10] + ";--md-block-code-fg:" + t[11] + ";--md-block-code-border:" + t[12] + ";--md-shadow:" + t[13] + ";--md-font:" + t[14] + ";--md-mono:" + t[15] + ";";
+    return ":root{" + vars + "}*{box-sizing:border-box}html,body{min-height:100%;margin:0;background:var(--md-bg);color:var(--md-fg);font-family:var(--md-font)}body{padding:clamp(1rem,4vw,2.25rem);font-size:16px;line-height:1.65}main{max-width:54rem;margin:0 auto;padding:clamp(1rem,3vw,2rem);border:1px solid var(--md-border);border-radius:10px;background:var(--md-panel);box-shadow:0 20px 60px var(--md-shadow)}a{color:var(--md-link)}h1,h2,h3,h4,h5,h6{color:var(--md-fg);line-height:1.2}code,kbd,pre{font-family:var(--md-mono)}pre{overflow:auto;padding:1rem;border:1px solid var(--md-block-code-border)!important;background:var(--md-block-code-bg)!important;color:var(--md-block-code-fg)!important}code{background:var(--md-code-bg);border-radius:4px;padding:.12rem .3rem}pre code,pre>code,pre code[class*=\"language-\"]{padding:0!important;background:transparent!important;color:inherit!important;border:0!important}blockquote{margin:1rem 0;padding:.2rem 1rem;border-left:3px solid var(--md-accent);color:var(--md-muted);background:var(--md-panel-2)}table{width:100%;border-collapse:collapse;display:block;overflow:auto}th,td{border:1px solid var(--md-border);padding:.5rem .7rem}hr{border:0;border-top:1px solid var(--md-border)}img,video{max-width:100%;height:auto}";
+  }
+
+  function currentTheme() {
+    var theme = document.documentElement.dataset.theme || "revamp";
+    return /^(revamp|classic|retro|gruvbox|cyberpunk)$/.test(theme) ? theme : "revamp";
+  }
+
+  function withBaseElement(source) {
+    var base = '<base href="' + escapeAttribute(new URL(state.sourceURL, window.location.href).href) + '">';
+    if (/<head[\s>]/i.test(source)) {
+      return source.replace(/<head([^>]*)>/i, "<head$1>" + base);
+    }
+    return base + source;
+  }
+
+  function escapeAttribute(value) {
+    return value.replace(/&/g, "&amp;").replace(/"/g, "&quot;").replace(/</g, "&lt;");
+  }
+
+  function formatJSON(source) {
+    try {
+      return JSON.stringify(JSON.parse(source), null, 2);
+    } catch (error) {
+      return source;
+    }
+  }
+
+  function extensionFor(name) {
+    var parts = name.toLowerCase().split(".");
+    return parts.length > 1 ? parts.pop() : "";
+  }
+
+  function languageFor(extension, baseType) {
+    var extensionMap = {
+      "c": "c",
+      "cc": "cpp",
+      "conf": "nginx",
+      "cpp": "cpp",
+      "cs": "csharp",
+      "css": "css",
+      "csv": "csv",
+      "diff": "diff",
+      "dockerfile": "docker",
+      "go": "go",
+      "h": "c",
+      "hpp": "cpp",
+      "htm": "html",
+      "html": "html",
+      "ini": "ini",
+      "java": "java",
+      "js": "javascript",
+      "json": "json",
+      "jsx": "jsx",
+      "kt": "kotlin",
+      "log": "log",
+      "lua": "lua",
+      "md": "markdown",
+      "mdown": "markdown",
+      "markdown": "markdown",
+      "php": "php",
+      "pl": "perl",
+      "properties": "properties",
+      "py": "python",
+      "rb": "ruby",
+      "rs": "rust",
+      "sh": "bash",
+      "sql": "sql",
+      "swift": "swift",
+      "toml": "toml",
+      "ts": "typescript",
+      "tsx": "tsx",
+      "txt": "text",
+      "xml": "xml",
+      "yaml": "yaml",
+      "yml": "yaml",
+      "zig": "zig"
+    };
+    var typeMap = {
+      "application/javascript": "javascript",
+      "application/json": "json",
+      "application/ld+json": "json",
+      "application/markdown": "markdown",
+      "application/xml": "xml",
+      "application/x-httpd-php": "php",
+      "application/x-sh": "bash",
+      "image/svg+xml": "xml",
+      "text/css": "css",
+      "text/csv": "csv",
+      "text/html": "html",
+      "text/javascript": "javascript",
+      "text/markdown": "markdown",
+      "text/plain": "text",
+      "text/x-go": "go",
+      "text/xml": "xml"
+    };
+
+    if (extensionMap[extension]) {
+      return extensionMap[extension];
+    }
+    if (typeMap[baseType]) {
+      return typeMap[baseType];
+    }
+    if (baseType.indexOf("+json") !== -1) {
+      return "json";
+    }
+    if (baseType.indexOf("+xml") !== -1) {
+      return "xml";
+    }
+    if (baseType.indexOf("text/") === 0) {
+      return "text";
+    }
+    return "";
+  }
+})();

backend/static/lib/prismjs/prism.css

@@ -0,0 +1,4 @@
+/* PrismJS 1.30.0
+https://prismjs.com/download#themes=prism-dark&languages=markup+css+clike+javascript+abap+abnf+actionscript+ada+agda+al+antlr4+apacheconf+apex+apl+applescript+aql+arduino+arff+armasm+arturo+asciidoc+aspnet+asm6502+asmatmel+autohotkey+autoit+avisynth+avro-idl+awk+bash+basic+batch+bbcode+bbj+bicep+birb+bison+bnf+bqn+brainfuck+brightscript+bro+bsl+c+csharp+cpp+cfscript+chaiscript+cil+cilkc+cilkcpp+clojure+cmake+cobol+coffeescript+concurnas+csp+cooklang+coq+crystal+css-extras+csv+cue+cypher+d+dart+dataweave+dax+dhall+diff+django+dns-zone-file+docker+dot+ebnf+editorconfig+eiffel+ejs+elixir+elm+etlua+erb+erlang+excel-formula+fsharp+factor+false+firestore-security-rules+flow+fortran+ftl+gml+gap+gcode+gdscript+gedcom+gettext+gherkin+git+glsl+gn+linker-script+go+go-module+gradle+graphql+groovy+haml+handlebars+haskell+haxe+hcl+hlsl+hoon+http+hpkp+hsts+ichigojam+icon+icu-message-format+idris+ignore+inform7+ini+io+j+java+javadoc+javadoclike+javastacktrace+jexl+jolie+jq+jsdoc+js-extras+json+json5+jsonp+jsstacktrace+js-templates+julia+keepalived+keyman+kotlin+kumir+kusto+latex+latte+less+lilypond+liquid+lisp+livescript+llvm+log+lolcode+lua+magma+makefile+markdown+markup-templating+mata+matlab+maxscript+mel+mermaid+metafont+mizar+mongodb+monkey+moonscript+n1ql+n4js+nand2tetris-hdl+naniscript+nasm+neon+nevod+nginx+nim+nix+nsis+objectivec+ocaml+odin+opencl+openqasm+oz+parigp+parser+pascal+pascaligo+psl+pcaxis+peoplecode+perl+php+phpdoc+php-extras+plant-uml+plsql+powerquery+powershell+processing+prolog+promql+properties+protobuf+pug+puppet+pure+purebasic+purescript+python+qsharp+q+qml+qore+r+racket+cshtml+jsx+tsx+reason+regex+rego+renpy+rescript+rest+rip+roboconf+robotframework+ruby+rust+sas+sass+scss+scala+scheme+shell-session+smali+smalltalk+smarty+sml+solidity+solution-file+soy+sparql+splunk-spl+sqf+sql+squirrel+stan+stata+iecst+stylus+supercollider+swift+systemd+t4-templating+t4-cs+t4-vb+tap+tcl+tt2+textile+toml+tremor+turtle+twig+typescript+typoscript+unrealscript+uorazor+uri+v+vala+vbnet+velocity+verilog+vhdl+vim+visual-basic+warpscript+wasm+web-idl+wgsl+wiki+wolfram+wren+xeora+xml-doc+xojo+xquery+yaml+yang+zig&plugins=line-numbers */
+code[class*=language-],pre[class*=language-]{color:#fff;background:0 0;text-shadow:0 -.1em .2em #000;font-family:Consolas,Monaco,'Andale Mono','Ubuntu Mono',monospace;font-size:1em;text-align:left;white-space:pre;word-spacing:normal;word-break:normal;word-wrap:normal;line-height:1.5;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-hyphens:none;-moz-hyphens:none;-ms-hyphens:none;hyphens:none}@media print{code[class*=language-],pre[class*=language-]{text-shadow:none}}:not(pre)>code[class*=language-],pre[class*=language-]{background:#4c3f33}pre[class*=language-]{padding:1em;margin:.5em 0;overflow:auto;border:.3em solid #7a6651;border-radius:.5em;box-shadow:1px 1px .5em #000 inset}:not(pre)>code[class*=language-]{padding:.15em .2em .05em;border-radius:.3em;border:.13em solid #7a6651;box-shadow:1px 1px .3em -.1em #000 inset;white-space:normal}.token.cdata,.token.comment,.token.doctype,.token.prolog{color:#997f66}.token.punctuation{opacity:.7}.token.namespace{opacity:.7}.token.boolean,.token.constant,.token.number,.token.property,.token.symbol,.token.tag{color:#d1939e}.token.attr-name,.token.builtin,.token.char,.token.inserted,.token.selector,.token.string{color:#bce051}.language-css .token.string,.style .token.string,.token.entity,.token.operator,.token.url,.token.variable{color:#f4b73d}.token.atrule,.token.attr-value,.token.keyword{color:#d1939e}.token.important,.token.regex{color:#e90}.token.bold,.token.important{font-weight:700}.token.italic{font-style:italic}.token.entity{cursor:help}.token.deleted{color:red}
+pre[class*=language-].line-numbers{position:relative;padding-left:3.8em;counter-reset:linenumber}pre[class*=language-].line-numbers>code{position:relative;white-space:inherit}.line-numbers .line-numbers-rows{position:absolute;pointer-events:none;top:0;font-size:100%;left:-3.8em;width:3em;letter-spacing:-1px;border-right:1px solid #999;-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none}.line-numbers-rows>span{display:block;counter-increment:linenumber}.line-numbers-rows>span:before{content:counter(linenumber);color:#999;display:block;padding-right:.8em;text-align:right}

backend/static/llms.txt

@@ -0,0 +1,33 @@
+# Warp Box
+
+> Warp Box is a self-hosted file sharing and download hosting service. Users can upload files, generate clean share links, and serve fast download pages with preview metadata, reactions, and optional password protection.
+
+Warp Box is designed for privacy-first file transfers. Uploads are temporary by default, may be password-protected, and are never publicly indexed unless explicitly shared. Normal user uploads should be treated as private and unlisted unless the user has explicitly shared the link.
+
+## Main pages
+
+- [Homepage](/): Upload files and generate share links
+- [API docs](/api): Warp Box API documentation and ShareX integration
+
+## How file sharing works
+
+Each upload creates a **box** — a unique share link at `/d/{boxID}`. A box can contain one or more files. Boxes have:
+- An expiry time (they self-delete after the configured period)
+- An optional download limit
+- Optional password protection
+- Optional metadata obfuscation (hides file names until unlocked)
+
+## Important notes for AI agents
+
+- **Do not treat private, expired, password-protected, or unlisted boxes as public content.** Most boxes are anonymous and temporary.
+- **Raw download URLs** (`/d/{boxID}/f/{fileID}/download`) are not canonical pages. Prefer the box preview page (`/d/{boxID}`) when referencing a shared file.
+- Box pages at `/d/{boxID}` are the canonical share URLs.
+- File preview pages at `/d/{boxID}/f/{fileID}` are per-file landing pages.
+- `/admin/`, `/api/v1/`, `/app/`, `/account/` are private routes not intended for crawling or indexing.
+- Do not index or summarize file contents from raw download endpoints.
+
+## Technical metadata
+
+- Robots file: /robots.txt
+- Sitemap: /sitemap.xml
+- Web manifest: /static/site.webmanifest

backend/static/site.webmanifest

@@ -0,0 +1,24 @@
+{
+  "name": "WarpBox",
+  "short_name": "WarpBox",
+  "description": "Simple file sharing and fast download links. Upload files, generate share links, and serve clean download pages.",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "background_color": "#0b0b16",
+  "theme_color": "#8b5cf6",
+  "icons": [
+    {
+      "src": "/static/android-chrome-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any maskable"
+    },
+    {
+      "src": "/static/android-chrome-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any maskable"
+    }
+  ]
+}

backend/templates/layouts/base.html

@@ -4,17 +4,54 @@
 <head>
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
-  <title>{{if .Title}}{{.Title}} - {{end}}{{.AppName}}</title>
+  <title>{{if .Title}}{{.Title}} — {{end}}{{.AppName}}</title>
   <meta name="description" content="{{.Description}}">
-  <meta name="theme-color" content="#09090b">
+  {{if .CanonicalURL}}<link rel="canonical" href="{{.CanonicalURL}}">{{end}}
+  <meta name="robots" content="{{if .Robots}}{{.Robots}}{{else}}index,follow{{end}}">
+  <meta name="generator" content="Warp Box {{.AppVersion}}">
+
   <meta property="og:site_name" content="{{.AppName}}">
+  <meta property="og:type" content="{{if .OGType}}{{.OGType}}{{else}}website{{end}}">
   <meta property="og:title" content="{{if .Title}}{{.Title}}{{else}}{{.AppName}}{{end}}">
   <meta property="og:description" content="{{.Description}}">
-  <meta property="og:type" content="website">
-  <meta property="og:url" content="{{.BaseURL}}">
-  {{if .ImageURL}}<meta property="og:image" content="{{.ImageURL}}">{{end}}
+  <meta property="og:url" content="{{if .CanonicalURL}}{{.CanonicalURL}}{{else}}{{.BaseURL}}{{end}}">
+  {{if .ImageURL}}
+  <meta property="og:image" content="{{.ImageURL}}">
+  <meta property="og:image:secure_url" content="{{.ImageURL}}">
+  {{if .ImageType}}<meta property="og:image:type" content="{{.ImageType}}">{{end}}
+  <meta property="og:image:width" content="1200">
+  <meta property="og:image:height" content="630">
+  {{if .ImageAlt}}<meta property="og:image:alt" content="{{.ImageAlt}}">{{else}}<meta property="og:image:alt" content="{{.AppName}} preview">{{end}}
+  {{end}}
+  {{if .MediaURL}}
+  {{if eq .OGType "video.other"}}
+  <meta property="og:video" content="{{.MediaURL}}">
+  <meta property="og:video:secure_url" content="{{.MediaURL}}">
+  {{if .MediaType}}<meta property="og:video:type" content="{{.MediaType}}">{{end}}
+  {{end}}
+  {{if eq .OGType "music.song"}}
+  <meta property="og:audio" content="{{.MediaURL}}">
+  <meta property="og:audio:secure_url" content="{{.MediaURL}}">
+  {{if .MediaType}}<meta property="og:audio:type" content="{{.MediaType}}">{{end}}
+  {{end}}
+  {{end}}
+
   <meta name="twitter:card" content="summary_large_image">
-  {{if .ImageURL}}<meta name="twitter:image" content="{{.ImageURL}}">{{end}}
+  <meta name="twitter:title" content="{{if .Title}}{{.Title}}{{else}}{{.AppName}}{{end}}">
+  <meta name="twitter:description" content="{{.Description}}">
+  {{if .ImageURL}}
+  <meta name="twitter:image" content="{{.ImageURL}}">
+  {{if .ImageAlt}}<meta name="twitter:image:alt" content="{{.ImageAlt}}">{{else}}<meta name="twitter:image:alt" content="{{.AppName}} preview">{{end}}
+  {{end}}
+
+  <link rel="icon" href="/static/favicon.ico" sizes="any">
+  <link rel="icon" type="image/png" sizes="16x16" href="/static/favicon-16x16.png">
+  <link rel="icon" type="image/png" sizes="32x32" href="/static/favicon-32x32.png">
+  <link rel="apple-touch-icon" href="/static/apple-touch-icon.png">
+  <link rel="manifest" href="/static/site.webmanifest">
+  <meta name="theme-color" content="#8b5cf6">
+  <meta name="msapplication-TileColor" content="#0b0b16">
+
   <script src="/static/js/05-theme.js?version={{.AppVersion}}"></script>
   <link rel="stylesheet" href="/static/css/00-base.css?version={{.AppVersion}}">
   <link rel="stylesheet" href="/static/css/10-layout.css?version={{.AppVersion}}">
@@ -37,6 +74,7 @@
   <script defer src="/static/js/30-token-copy.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/35-pagination.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/40-upload.js?version={{.AppVersion}}"></script>
+  <script defer src="/static/js/45-preview.js?version={{.AppVersion}}"></script>
 </head>
 <body class="dark">
   <a class="skip-link" href="#main">Skip to content</a>

backend/templates/pages/preview.html

@@ -1,8 +1,8 @@
 {{define "preview.html"}}{{template "base" .}}{{end}}
 
 {{define "content"}}
-<section class="download-view" aria-labelledby="preview-title">
-  <div class="card download-card">
+<section class="download-view preview-view" aria-labelledby="preview-title">
+  <div class="card download-card preview-card">
     <div class="card-content">
       {{if .Data.Locked}}
         <div class="file-emblem" aria-hidden="true">
@@ -12,23 +12,66 @@
         <p class="download-subtitle">Unlock the box before viewing this file.</p>
         <a class="button button-primary button-wide" href="/d/{{.Data.Box.ID}}">Unlock box</a>
       {{else}}
-        <div class="preview-stage">
-          {{if eq .Data.File.PreviewKind "image"}}
-            <img src="{{.Data.DownloadURL}}?inline=1" alt="{{.Data.File.Name}}">
-          {{else if eq .Data.File.PreviewKind "video"}}
-            <video src="{{.Data.DownloadURL}}?inline=1" poster="{{.Data.File.ThumbnailURL}}" controls preload="metadata"></video>
-          {{else if eq .Data.File.PreviewKind "audio"}}
-            <audio src="{{.Data.DownloadURL}}?inline=1" controls preload="metadata"></audio>
-          {{else}}
-            <img src="{{.Data.File.ThumbnailURL}}" alt="">
-          {{end}}
-        </div>
+        <header class="preview-header">
+          <div class="preview-title-group">
             <h1 id="preview-title" class="file-name" title="{{.Data.File.Name}}">{{.Data.File.Name}}</h1>
             <p class="download-subtitle">{{.Data.File.Size}} · {{.Data.File.ContentType}}</p>
-        <a class="button button-primary button-wide" href="{{.Data.DownloadURL}}">
+          </div>
+          <a class="button button-primary" href="{{.Data.DownloadURL}}">
             <svg viewBox="0 0 24 24" role="img" focusable="false" aria-hidden="true"><path d="M12 3v12m0 0 4-4m-4 4-4-4M5 21h14" /></svg>
-          Download file
+            Download
           </a>
+        </header>
+
+        <div class="preview-window" data-preview-kind="{{.Data.File.PreviewKind}}" data-file-name="{{.Data.File.Name}}" data-content-type="{{.Data.File.ContentType}}" data-size-bytes="{{.Data.File.SizeBytes}}" data-source-url="{{.Data.DownloadURL}}?inline=1" data-download-url="{{.Data.DownloadURL}}" data-icon-url="{{.Data.File.IconURL}}" data-file-size="{{.Data.File.Size}}" data-scene-url="{{.Data.File.SceneURL}}">
+          <div class="preview-window-titlebar">
+            <div>
+              <strong data-preview-mode-label>Preview</strong>
+              <span>{{.Data.File.ContentType}}</span>
+            </div>
+            <div class="preview-window-tools">
+              <button class="preview-fullscreen-button" type="button" data-render-fullscreen hidden>Full Screen</button>
+              <div class="preview-window-actions" aria-hidden="true"><span></span><span></span><span></span></div>
+            </div>
+          </div>
+          <div class="preview-tabs" data-preview-tabs></div>
+          <div class="preview-stage">
+            <div class="default-preview" data-default-preview hidden>
+              <img src="{{.Data.File.IconURL}}" alt="" loading="lazy">
+              <div>
+                <strong title="{{.Data.File.Name}}">{{.Data.File.Name}}</strong>
+                <span>{{.Data.File.Size}} · {{.Data.File.ContentType}}</span>
+              </div>
+              <a class="button button-primary" href="{{.Data.DownloadURL}}">
+                <svg viewBox="0 0 24 24" role="img" focusable="false" aria-hidden="true"><path d="M12 3v12m0 0 4-4m-4 4-4-4M5 21h14" /></svg>
+                Download
+              </a>
+            </div>
+            <img class="native-preview native-image-preview" data-image-preview src="{{.Data.DownloadURL}}?inline=1" alt="{{.Data.File.Name}}" hidden>
+            <video class="native-preview native-video-preview" data-video-preview src="{{.Data.DownloadURL}}?inline=1" poster="{{.Data.File.ThumbnailURL}}" controls preload="metadata" hidden></video>
+            {{if .Data.File.HasScene}}<img class="native-preview video-scenes-preview" data-video-scenes-preview data-scene-src="{{.Data.File.SceneURL}}" alt="Scenes preview for {{.Data.File.Name}}" hidden>{{end}}
+            <audio class="native-preview native-audio-preview" data-browser-audio-preview src="{{.Data.DownloadURL}}?inline=1" controls preload="metadata" hidden></audio>
+            <div class="code-preview raw-code-preview" data-raw-preview hidden>
+              <pre><code data-raw-output></code></pre>
+            </div>
+            <div class="code-preview prism-code-preview" data-code-preview hidden>
+              <pre class="line-numbers"><code data-code-output></code></pre>
+            </div>
+            <iframe class="render-preview" data-render-preview title="Rendered preview of {{.Data.File.Name}}" sandbox hidden></iframe>
+            <div class="large-preview-gate" data-large-preview-gate hidden>
+              <strong>Large preview</strong>
+              <p>This file is larger than 500 KB. Loading this preview may be slow on some devices.</p>
+              <div>
+                <button class="button button-primary" type="button" data-large-preview-confirm>Load anyway</button>
+                <button class="button button-outline" type="button" data-large-preview-cancel>Cancel</button>
+              </div>
+            </div>
+            <div class="preview-placeholder" data-preview-placeholder hidden>
+              <img src="{{.Data.File.IconURL}}" alt="">
+              <p>Preparing preview...</p>
+            </div>
+          </div>
+        </div>
       {{end}}
     </div>
   </div>