feat(backend): handle processing errors and add PWA routes

- Block file downloads and previews with a 424 StatusFailedDependency if file processing failed or the box has issues. - Register routes for `/service-worker.js` and `/share-target` to support PWA features. - Update README.md with an AI usage disclosure.
2026-06-08 11:53:37 +03:00
parent dbfdacc396
commit d11aec96e5
26 changed files with 1186 additions and 35 deletions
--- a/README.md
+++ b/README.md
@@ -357,3 +357,9 @@ bbolt database and JSON logs always remain local under `./data/db` and `./data/l

 The static handler sets long-lived immutable caching for images, video, audio, and fonts, shorter
 caching for CSS/JS, and gzip compression for compressible responses.
+
+## AI Usage
+
+I have used AI to accelerate development, all of the code has been reviewed by humans. I have mostly used self-hosted models as well as big models from big companies for a monthly subscription fee. 
+
+I have nothing against AI as long as you can tell me what every single line of your code does. That's how I personally view things.
--- a/backend/libs/handlers/app.go
+++ b/backend/libs/handlers/app.go
@@ -54,6 +54,8 @@ func (a *App) renderPage(w http.ResponseWriter, r *http.Request, status int, pag
 func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /", a.Home)
 	mux.HandleFunc("GET /api", a.APIDocs)
+	mux.HandleFunc("GET /service-worker.js", a.ServiceWorker)
+	mux.HandleFunc("POST /share-target", a.ShareTargetFallback)
 	mux.HandleFunc("GET /register", a.Register)
 	mux.HandleFunc("POST /register", a.RegisterPost)
 	mux.HandleFunc("GET /login", a.Login)
--- a/backend/libs/handlers/download.go
+++ b/backend/libs/handlers/download.go
@@ -59,6 +59,8 @@ type fileView struct {
 	ReactionMore int
 	Reacted      bool
 	Processing   bool
+	Failed       bool
+	Error        string
 }

 type reactionView struct {
@@ -242,12 +244,32 @@ func (a *App) DownloadFile(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, "file is still processing", http.StatusAccepted)
 			return
 		}
+		if file.ProcessingError != "" {
+			a.logger.Warn("failed file preview blocked for social bot", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4241, "box_id", box.ID, "file_id", file.ID, "error", file.ProcessingError)...)
+			http.Error(w, "file processing failed: "+file.ProcessingError, http.StatusFailedDependency)
+			return
+		}
+		if services.BoxHasTrouble(box) {
+			a.logger.Warn("failed box preview blocked for social bot", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4245, "box_id", box.ID, "file_id", file.ID, "error", services.BoxTroubleReason(box))...)
+			http.Error(w, "box processing failed: "+services.BoxTroubleReason(box), http.StatusFailedDependency)
+			return
+		}
 		if shouldServeRawSocialMedia(file) {
 			a.serveFileContent(w, r, box, file, false)
 			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
 		}
 	}
+	if file.ProcessingError != "" && !locked {
+		a.logger.Warn("failed file preview blocked", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4242, "box_id", box.ID, "file_id", file.ID, "error", file.ProcessingError)...)
+		http.Error(w, "file processing failed: "+file.ProcessingError, http.StatusFailedDependency)
+		return
+	}
+	if services.BoxHasTrouble(box) && !locked {
+		a.logger.Warn("failed box preview blocked", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4246, "box_id", box.ID, "file_id", file.ID, "error", services.BoxTroubleReason(box))...)
+		http.Error(w, "box processing failed: "+services.BoxTroubleReason(box), http.StatusFailedDependency)
+		return
+	}
 	view := a.fileView(box, file)
 	fileSize := helpers.FormatBytes(file.Size)
 	title := file.Name
@@ -306,6 +328,16 @@ func (a *App) DownloadFileContent(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "file is still processing", http.StatusAccepted)
 		return
 	}
+	if file.ProcessingError != "" {
+		a.logger.Warn("failed file download blocked", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4243, "box_id", box.ID, "file_id", file.ID, "error", file.ProcessingError)...)
+		http.Error(w, "file processing failed: "+file.ProcessingError, http.StatusFailedDependency)
+		return
+	}
+	if services.BoxHasTrouble(box) {
+		a.logger.Warn("failed box download blocked", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4247, "box_id", box.ID, "file_id", file.ID, "error", services.BoxTroubleReason(box))...)
+		http.Error(w, "box processing failed: "+services.BoxTroubleReason(box), http.StatusFailedDependency)
+		return
+	}

 	a.serveFileContent(w, r, box, file, r.URL.Query().Get("inline") != "1")
 	a.logger.Info("file content served", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2005, "box_id", box.ID, "file_id", file.ID, "attachment", r.URL.Query().Get("inline") != "1")...)
@@ -321,6 +353,11 @@ func (a *App) Thumbnail(w http.ResponseWriter, r *http.Request) {
 		a.servePlaceholderThumbnail(w, r)
 		return
 	}
+	if services.BoxHasTrouble(box) || services.FileHasTrouble(file) {
+		a.logger.Warn("thumbnail request skipped trouble file", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4110, "box_id", box.ID, "file_id", file.ID, "error", troubleReasonForLog(box, file))...)
+		a.servePlaceholderThumbnail(w, r)
+		return
+	}

 	object, err := a.uploadService.OpenThumbnailObject(r.Context(), box, file)
 	if err != nil {
@@ -363,6 +400,11 @@ func (a *App) VideoScenesPreview(w http.ResponseWriter, r *http.Request) {
 		a.servePlaceholderThumbnail(w, r)
 		return
 	}
+	if services.BoxHasTrouble(box) || services.FileHasTrouble(file) {
+		a.logger.Warn("video scenes preview request skipped trouble file", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4111, "box_id", box.ID, "file_id", file.ID, "error", troubleReasonForLog(box, file))...)
+		a.servePlaceholderThumbnail(w, r)
+		return
+	}

 	object, err := a.uploadService.OpenSceneThumbnailObject(r.Context(), box, file)
 	if err != nil {
@@ -400,6 +442,11 @@ func (a *App) ArchiveListing(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "password required", http.StatusUnauthorized)
 		return
 	}
+	if services.BoxHasTrouble(box) || services.FileHasTrouble(file) {
+		a.logger.Warn("archive listing request skipped trouble file", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4112, "box_id", box.ID, "file_id", file.ID, "error", troubleReasonForLog(box, file))...)
+		http.Error(w, "archive preview unavailable: file processing failed", http.StatusFailedDependency)
+		return
+	}

 	if strings.ToLower(filepath.Ext(file.ArchiveListing)) != ".json" {
 		if listing := a.generateMissingArchiveListingForRequest(r, box, file); listing != "" {
@@ -432,7 +479,7 @@ func (a *App) ArchiveListing(w http.ResponseWriter, r *http.Request) {
 }

 func (a *App) generateMissingThumbnailForRequest(r *http.Request, box services.Box, file services.File) string {
-	if file.Thumbnail != "" || !jobs.NeedsThumbnail(file) {
+	if file.Thumbnail != "" || !jobs.NeedsThumbnail(file) || services.BoxHasTrouble(box) || services.FileHasTrouble(file) || file.Processing {
 		return ""
 	}
 	thumbnail, err := jobs.GenerateThumbnailForFile(a.uploadService, box, file)
@@ -456,7 +503,7 @@ func (a *App) generateMissingThumbnailForRequest(r *http.Request, box services.B
 }

 func (a *App) generateMissingVideoScenesForRequest(r *http.Request, box services.Box, file services.File) string {
-	if file.SceneThumbnail != "" || !jobs.NeedsVideoScenes(file) {
+	if file.SceneThumbnail != "" || !jobs.NeedsVideoScenes(file) || services.BoxHasTrouble(box) || services.FileHasTrouble(file) || file.Processing {
 		return ""
 	}
 	scene, err := jobs.GenerateVideoScenesForFile(a.uploadService, box, file)
@@ -480,7 +527,7 @@ func (a *App) generateMissingVideoScenesForRequest(r *http.Request, box services
 }

 func (a *App) generateMissingArchiveListingForRequest(r *http.Request, box services.Box, file services.File) string {
-	if strings.ToLower(filepath.Ext(file.ArchiveListing)) == ".json" || !jobs.NeedsArchiveListing(file) {
+	if strings.ToLower(filepath.Ext(file.ArchiveListing)) == ".json" || !jobs.NeedsArchiveListing(file) || services.BoxHasTrouble(box) || services.FileHasTrouble(file) || file.Processing {
 		return ""
 	}
 	listing, err := jobs.GenerateArchiveListingForFile(a.uploadService, box, file)
@@ -504,6 +551,13 @@ func (a *App) generateMissingArchiveListingForRequest(r *http.Request, box servi
 	return listing
 }

+func troubleReasonForLog(box services.Box, file services.File) string {
+	if services.FileHasTrouble(file) {
+		return file.ProcessingError
+	}
+	return services.BoxTroubleReason(box)
+}
+
 // 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.
@@ -651,6 +705,22 @@ func (a *App) DownloadZip(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "password required", http.StatusUnauthorized)
 		return
 	}
+	for _, file := range box.Files {
+		if file.Processing {
+			http.Error(w, "file is still processing", http.StatusAccepted)
+			return
+		}
+		if file.ProcessingError != "" {
+			a.logger.Warn("zip download blocked by failed file", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4244, "box_id", box.ID, "file_id", file.ID, "error", file.ProcessingError)...)
+			http.Error(w, "file processing failed: "+file.ProcessingError, http.StatusFailedDependency)
+			return
+		}
+	}
+	if services.BoxHasTrouble(box) {
+		a.logger.Warn("zip download blocked by failed box", withRequestLogAttrs(r, "source", "download", "severity", "warn", "code", 4248, "box_id", box.ID, "error", services.BoxTroubleReason(box))...)
+		http.Error(w, "box processing failed: "+services.BoxTroubleReason(box), http.StatusFailedDependency)
+		return
+	}

 	w.Header().Set("Content-Type", "application/zip")
 	w.Header().Set("Content-Disposition", contentDisposition("attachment", "warpbox-"+box.ID+".zip"))
@@ -685,9 +755,9 @@ func (a *App) fileViewWithReactions(box services.Box, file services.File, reacti
 		ThumbnailURL: fmt.Sprintf("/d/%s/thumb/%s", box.ID, file.ID),
 		SceneURL:     fmt.Sprintf("/d/%s/scene/%s", box.ID, file.ID),
 		ArchiveURL:   fmt.Sprintf("/d/%s/archive/%s", box.ID, file.ID),
-		HasThumbnail: file.Thumbnail != "" || jobs.NeedsThumbnail(file),
-		HasScene:     file.SceneThumbnail != "" || jobs.NeedsVideoScenes(file),
-		HasArchive:   file.ArchiveListing != "" || jobs.NeedsArchiveListing(file),
+		HasThumbnail: !services.BoxHasTrouble(box) && !services.FileHasTrouble(file) && (file.Thumbnail != "" || jobs.NeedsThumbnail(file)),
+		HasScene:     !services.BoxHasTrouble(box) && !services.FileHasTrouble(file) && (file.SceneThumbnail != "" || jobs.NeedsVideoScenes(file)),
+		HasArchive:   !services.BoxHasTrouble(box) && !services.FileHasTrouble(file) && (file.ArchiveListing != "" || jobs.NeedsArchiveListing(file)),
 		IconURL:      fileIconURL("standard", icon.Standard),
 		IconRetroURL: fileIconURL("retro", icon.Retro),
 		ReactURL:     fmt.Sprintf("/d/%s/f/%s/react", box.ID, file.ID),
@@ -695,6 +765,8 @@ func (a *App) fileViewWithReactions(box services.Box, file services.File, reacti
 		ReactionMore: reactionOverflowCount(reactionViews),
 		Reacted:      reacted,
 		Processing:   file.Processing,
+		Failed:       services.BoxHasTrouble(box) || services.FileHasTrouble(file),
+		Error:        troubleReasonForLog(box, file),
 	}
 }

--- a/backend/libs/handlers/pages.go
+++ b/backend/libs/handlers/pages.go
@@ -10,6 +10,7 @@ import (

 type homeData struct {
 	MaxUploadSize        string
+	MaxUploadBytes       int64
 	LimitSummary         string
 	Collections          []collectionView
 	IsAdmin              bool
@@ -57,7 +58,7 @@ func (a *App) Home(w http.ResponseWriter, r *http.Request) {
 		"actor", actor,
 		"user_id", user.ID,
 	)...)
-	maxUploadSize, limitSummary := a.homeUploadPolicyLabels(settings, user, loggedIn, isAdmin)
+	maxUploadSize, maxUploadBytes, limitSummary := a.homeUploadPolicyLabels(settings, user, loggedIn, isAdmin)
 	expiryOptions, defaultExpiry := a.homeExpiryOptions(settings, user, loggedIn, isAdmin)
 	a.renderPage(w, r, http.StatusOK, "home.html", web.PageData{
 		Title:        "Upload your files",
@@ -68,6 +69,7 @@ func (a *App) Home(w http.ResponseWriter, r *http.Request) {
 		CurrentUser:  currentUser,
 		Data: homeData{
 			MaxUploadSize:        maxUploadSize,
+			MaxUploadBytes:       maxUploadBytes,
 			LimitSummary:         limitSummary,
 			Collections:          collections,
 			IsAdmin:              isAdmin,
@@ -155,22 +157,25 @@ func expiryLabel(minutes int) string {
 	}
 }

-func (a *App) homeUploadPolicyLabels(settings services.UploadPolicySettings, user services.User, loggedIn, isAdmin bool) (string, string) {
+func (a *App) homeUploadPolicyLabels(settings services.UploadPolicySettings, user services.User, loggedIn, isAdmin bool) (string, int64, string) {
 	if isAdmin {
-		return "No file size limit", "Admin uploads bypass storage and daily caps."
+		return "No file size limit", -1, "Admin uploads bypass storage and daily caps."
 	}
 	if !loggedIn {
 		if !settings.AnonymousUploadsEnabled {
-			return "Anonymous uploads disabled", "Sign in to upload files."
+			return "Anonymous uploads disabled", 0, "Sign in to upload files."
 		}
-		return services.FormatMegabytesLabel(settings.AnonymousMaxUploadMB), "Daily anonymous cap: " + services.FormatMegabytesLabel(settings.AnonymousDailyUploadMB) + " per IP · " + strconv.Itoa(settings.AnonymousMaxDays) + " day max."
+		return services.FormatMegabytesLabel(settings.AnonymousMaxUploadMB), services.MegabytesToBytes(settings.AnonymousMaxUploadMB), "Daily anonymous cap: " + services.FormatMegabytesLabel(settings.AnonymousDailyUploadMB) + " per IP · " + strconv.Itoa(settings.AnonymousMaxDays) + " day max."
 	}
 	policy := a.settingsService.EffectivePolicyForUser(settings, user)
 	maxUpload := a.uploadService.MaxUploadSizeLabel()
+	maxUploadBytes := a.uploadService.MaxUploadSize()
 	if policy.MaxUploadMB < 0 {
 		maxUpload = "unlimited"
+		maxUploadBytes = -1
 	} else if policy.MaxUploadMB > 0 {
 		maxUpload = services.FormatMegabytesLabel(policy.MaxUploadMB)
+		maxUploadBytes = services.MegabytesToBytes(policy.MaxUploadMB)
 	}
 	quota := "unlimited"
 	if policy.StorageQuotaSet {
@@ -180,5 +185,5 @@ func (a *App) homeUploadPolicyLabels(settings services.UploadPolicySettings, use
 	if policy.MaxDays < 0 {
 		expiryLimit = "no expiry limit."
 	}
-	return maxUpload, "Daily cap: " + services.FormatMegabytesLabel(policy.DailyUploadMB) + " · Storage quota: " + quota + " · " + expiryLimit
+	return maxUpload, maxUploadBytes, "Daily cap: " + services.FormatMegabytesLabel(policy.DailyUploadMB) + " · Storage quota: " + quota + " · " + expiryLimit
 }
--- a/backend/libs/handlers/resumable.go
+++ b/backend/libs/handlers/resumable.go
@@ -180,7 +180,7 @@ func (a *App) CompleteResumableUpload(w http.ResponseWriter, r *http.Request) {
 	if !ok {
 		return
 	}
-	if session.Status == services.ResumableStatusCompleted || session.Status == services.ResumableStatusProcessing {
+	if session.Status == services.ResumableStatusCompleted {
 		result, completed, err := a.uploadService.CompleteResumableSession(r.Context(), session.ID)
 		if err != nil {
 			a.logger.Warn("resumable upload completion replay failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4004, "session_id", session.ID, "error", err.Error())...)
@@ -191,6 +191,17 @@ func (a *App) CompleteResumableUpload(w http.ResponseWriter, r *http.Request) {
 		helpers.WriteJSON(w, http.StatusOK, result)
 		return
 	}
+	if session.Status == services.ResumableStatusProcessing {
+		result, err := a.uploadService.FinalizeProcessingResumableSession(r.Context(), session.ID)
+		if err != nil {
+			a.logger.Warn("resumable upload completion replay failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4004, "session_id", session.ID, "error", err.Error())...)
+			helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		a.logger.Info("resumable upload completion replayed", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2004, "session_id", session.ID, "box_id", result.BoxID, "files", len(result.Files))...)
+		helpers.WriteJSON(w, http.StatusOK, result)
+		return
+	}
 	user, loggedIn, _ := a.currentUserWithAuthError(r)
 	isAdminUpload := loggedIn && user.Role == services.UserRoleAdmin
 	settings, policy, ok := a.loadUploadPolicyForAPI(w, r, user, loggedIn)
--- a/backend/libs/handlers/static.go
+++ b/backend/libs/handlers/static.go
@@ -34,6 +34,17 @@ func (a *App) EmojiAsset(w http.ResponseWriter, r *http.Request) {
 	http.ServeFile(w, r, path)
 }

+func (a *App) ServiceWorker(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/javascript; charset=utf-8")
+	w.Header().Set("Cache-Control", "public, max-age=86400")
+	w.Header().Set("Service-Worker-Allowed", "/")
+	http.ServeFile(w, r, filepath.Join(a.cfg.StaticDir, "js", "service-worker.js"))
+}
+
+func (a *App) ShareTargetFallback(w http.ResponseWriter, r *http.Request) {
+	http.Redirect(w, r, "/?share-target=unsupported", http.StatusSeeOther)
+}
+
 func setStaticCacheHeaders(w http.ResponseWriter, path string) {
 	ext := strings.ToLower(filepath.Ext(path))

--- a/backend/libs/handlers/static_test.go
+++ b/backend/libs/handlers/static_test.go
@@ -1,7 +1,11 @@
 package handlers

 import (
+	"encoding/json"
+	"net/http"
 	"net/http/httptest"
+	"os"
+	"path/filepath"
 	"testing"
 )

@@ -24,3 +28,76 @@ func TestSetStaticCacheHeaders(t *testing.T) {
 		}
 	}
 }
+
+func TestWebManifestIncludesShareTarget(t *testing.T) {
+	data, err := os.ReadFile(filepath.Join("..", "..", "static", "site.webmanifest"))
+	if err != nil {
+		t.Fatalf("ReadFile returned error: %v", err)
+	}
+	var manifest struct {
+		ShareTarget struct {
+			Action  string `json:"action"`
+			Method  string `json:"method"`
+			EncType string `json:"enctype"`
+			Params  struct {
+				Title string `json:"title"`
+				Text  string `json:"text"`
+				URL   string `json:"url"`
+				Files []struct {
+					Name   string   `json:"name"`
+					Accept []string `json:"accept"`
+				} `json:"files"`
+			} `json:"params"`
+		} `json:"share_target"`
+	}
+	if err := json.Unmarshal(data, &manifest); err != nil {
+		t.Fatalf("json.Unmarshal returned error: %v", err)
+	}
+	if manifest.ShareTarget.Action != "/share-target" || manifest.ShareTarget.Method != "POST" || manifest.ShareTarget.EncType != "multipart/form-data" {
+		t.Fatalf("unexpected share_target config: %+v", manifest.ShareTarget)
+	}
+	if manifest.ShareTarget.Params.Title != "title" || manifest.ShareTarget.Params.Text != "text" || manifest.ShareTarget.Params.URL != "url" {
+		t.Fatalf("unexpected share_target params: %+v", manifest.ShareTarget.Params)
+	}
+	if len(manifest.ShareTarget.Params.Files) != 1 || manifest.ShareTarget.Params.Files[0].Name != "files" || len(manifest.ShareTarget.Params.Files[0].Accept) != 1 || manifest.ShareTarget.Params.Files[0].Accept[0] != "*/*" {
+		t.Fatalf("unexpected share_target files: %+v", manifest.ShareTarget.Params.Files)
+	}
+}
+
+func TestServiceWorkerServedFromRootScope(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	request := httptest.NewRequest(http.MethodGet, "/service-worker.js", nil)
+	response := httptest.NewRecorder()
+	app.ServiceWorker(response, request)
+
+	if response.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
+	}
+	if got := response.Header().Get("Service-Worker-Allowed"); got != "/" {
+		t.Fatalf("Service-Worker-Allowed = %q, want /", got)
+	}
+	if got := response.Header().Get("Content-Type"); got != "text/javascript; charset=utf-8" {
+		t.Fatalf("Content-Type = %q", got)
+	}
+	if response.Body.Len() == 0 {
+		t.Fatalf("service worker body missing")
+	}
+}
+
+func TestShareTargetFallbackRedirectsHome(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	request := httptest.NewRequest(http.MethodPost, "/share-target", nil)
+	response := httptest.NewRecorder()
+	app.ShareTargetFallback(response, request)
+
+	if response.Code != http.StatusSeeOther {
+		t.Fatalf("status = %d, want %d", response.Code, http.StatusSeeOther)
+	}
+	if got := response.Header().Get("Location"); got != "/?share-target=unsupported" {
+		t.Fatalf("Location = %q", got)
+	}
+}
--- a/backend/libs/handlers/upload.go
+++ b/backend/libs/handlers/upload.go
@@ -53,6 +53,11 @@ func (a *App) Upload(w http.ResponseWriter, r *http.Request) {
 	}
 	if err := r.ParseMultipartForm(parseLimit); err != nil {
 		a.logger.Warn("upload form parse failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4000, "user_id", user.ID, "error", err.Error())...)
+		var maxBytesErr *http.MaxBytesError
+		if errors.As(err, &maxBytesErr) {
+			helpers.WriteJSONError(w, http.StatusRequestEntityTooLarge, "upload exceeds the configured upload limit")
+			return
+		}
 		helpers.WriteJSONError(w, http.StatusBadRequest, "upload form could not be read")
 		return
 	}
@@ -244,7 +249,7 @@ func (a *App) checkUploadPolicyForSizes(r *http.Request, user services.User, log
 		maxBytes := services.MegabytesToBytes(policy.MaxUploadMB)
 		for _, fileSize := range fileSizes {
 			if fileSize > maxBytes {
-				return http.StatusRequestEntityTooLarge, "file exceeds upload size limit"
+				return http.StatusRequestEntityTooLarge, "file exceeds upload size limit of " + services.FormatMegabytesLabel(policy.MaxUploadMB)
 			}
 		}
 	}
--- a/backend/libs/handlers/upload_stage3_test.go
+++ b/backend/libs/handlers/upload_stage3_test.go
@@ -218,6 +218,44 @@ func TestFilePreviewPageIncludesPreviewMetadata(t *testing.T) {
 	}
 }

+func TestDownloadPageShowsProcessingFailure(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+	payload := uploadThroughApp(t, app)
+	box, err := app.uploadService.GetBox(payload.BoxID)
+	if err != nil {
+		t.Fatalf("GetBox returned error: %v", err)
+	}
+	box.Files[0].Processing = false
+	box.Files[0].ProcessingError = "Access Denied."
+	if err := app.uploadService.SaveBox(box); err != nil {
+		t.Fatalf("SaveBox returned error: %v", err)
+	}
+
+	request := httptest.NewRequest(http.MethodGet, "/d/"+payload.BoxID, nil)
+	request.SetPathValue("boxID", payload.BoxID)
+	response := httptest.NewRecorder()
+	app.DownloadPage(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{
+		"Upload processing failed",
+		"Access Denied.",
+		"is-failed",
+		"Failed",
+	} {
+		if !strings.Contains(body, want) {
+			t.Fatalf("download page missing %q: %s", want, body)
+		}
+	}
+	if strings.Contains(body, `data-download-url="/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/download"`) {
+		t.Fatalf("failed file still exposed download context: %s", body)
+	}
+}
+
 func TestFileDownloadUsesOriginalFilename(t *testing.T) {
 	app, cleanup := newTestApp(t)
 	defer cleanup()
--- a/backend/libs/jobs/thumbnails.go
+++ b/backend/libs/jobs/thumbnails.go
@@ -45,6 +45,10 @@ func GenerateThumbnailsForBoxAsync(uploadService *services.UploadService, logger
 			logger.Warn("thumbnail box lookup failed", "source", "thumbnail", "severity", "warn", "code", 4204, "box_id", boxID, "error", err.Error())
 			return
 		}
+		if services.BoxHasTrouble(box) {
+			logger.Warn("thumbnail one-shot skipped trouble box", "source", "thumbnail", "severity", "warn", "code", 4206, "box_id", boxID, "error", services.BoxTroubleReason(box))
+			return
+		}

 		result, err := generateMissingThumbnailsForBox(uploadService, logger, box)
 		if err != nil {
@@ -91,6 +95,9 @@ func generateMissingThumbnails(uploadService *services.UploadService, logger *sl
 		if !box.ExpiresAt.After(now) {
 			continue
 		}
+		if services.BoxHasTrouble(box) {
+			continue
+		}

 		boxResult, err := generateMissingThumbnailsForBox(uploadService, logger, box)
 		result.Scanned += boxResult.Scanned
@@ -109,10 +116,16 @@ func generateMissingThumbnailsForBox(uploadService *services.UploadService, logg
 	if !box.ExpiresAt.After(time.Now().UTC()) {
 		return result, nil
 	}
+	if services.BoxHasTrouble(box) {
+		return result, nil
+	}

 	changed := false
 	for i := range box.Files {
 		file := &box.Files[i]
+		if file.Processing || services.FileHasTrouble(*file) {
+			continue
+		}
 		needsPrimary := file.Thumbnail == "" && needsThumbnail(*file)
 		needsScenes := file.SceneThumbnail == "" && needsVideoScenes(*file)
 		needsArchive := !archiveListingCurrent(*file) && needsArchiveListing(*file)
@@ -206,6 +219,15 @@ func GenerateArchiveListingForFile(uploadService *services.UploadService, box se
 }

 func generateThumbnail(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
+	if services.BoxHasTrouble(box) {
+		return "", fmt.Errorf("box is marked as trouble: %s", services.BoxTroubleReason(box))
+	}
+	if file.Processing {
+		return "", fmt.Errorf("file is still processing")
+	}
+	if services.FileHasTrouble(file) {
+		return "", fmt.Errorf("file processing failed: %s", file.ProcessingError)
+	}
 	thumbnailName := "@thumb@" + file.ID + ".jpg"
 	object, err := uploadService.OpenFileObject(context.Background(), box, file)
 	if err != nil {
@@ -244,6 +266,15 @@ func generateVideoScenesThumbnail(uploadService *services.UploadService, box ser
 	if !needsVideoScenes(file) {
 		return "", nil
 	}
+	if services.BoxHasTrouble(box) {
+		return "", fmt.Errorf("box is marked as trouble: %s", services.BoxTroubleReason(box))
+	}
+	if file.Processing {
+		return "", fmt.Errorf("file is still processing")
+	}
+	if services.FileHasTrouble(file) {
+		return "", fmt.Errorf("file processing failed: %s", file.ProcessingError)
+	}
 	sceneName := "@scene@" + file.ID + ".jpg"
 	object, err := uploadService.OpenFileObject(context.Background(), box, file)
 	if err != nil {
@@ -263,6 +294,15 @@ func generateArchiveListing(uploadService *services.UploadService, box services.
 	if !needsArchiveListing(file) {
 		return "", nil
 	}
+	if services.BoxHasTrouble(box) {
+		return "", fmt.Errorf("box is marked as trouble: %s", services.BoxTroubleReason(box))
+	}
+	if file.Processing {
+		return "", fmt.Errorf("file is still processing")
+	}
+	if services.FileHasTrouble(file) {
+		return "", fmt.Errorf("file processing failed: %s", file.ProcessingError)
+	}
 	listingName := "@archive@" + file.ID + ".json"
 	object, err := uploadService.OpenFileObject(context.Background(), box, file)
 	if err != nil {
--- a/backend/libs/jobs/thumbnails_test.go
+++ b/backend/libs/jobs/thumbnails_test.go
@@ -50,6 +50,36 @@ func TestGenerateMissingThumbnailsForBox(t *testing.T) {
 	}
 }

+func TestGenerateMissingThumbnailsForTroubleBoxSkipsWork(t *testing.T) {
+	service := newThumbnailTestUploadService(t)
+	result := createThumbnailTestBox(t, service)
+	box, err := service.GetBox(result.BoxID)
+	if err != nil {
+		t.Fatalf("GetBox returned error: %v", err)
+	}
+	box.Trouble = true
+	box.TroubleReason = "storage backend failed"
+	if err := service.SaveBox(box); err != nil {
+		t.Fatalf("SaveBox returned error: %v", err)
+	}
+
+	jobResult, err := generateMissingThumbnailsForBox(service, slog.New(slog.NewTextHandler(io.Discard, nil)), box)
+	if err != nil {
+		t.Fatalf("generateMissingThumbnailsForBox returned error: %v", err)
+	}
+	if jobResult != (ThumbnailJobResult{}) {
+		t.Fatalf("job result = %+v, want no work for trouble box", jobResult)
+	}
+
+	updated, err := service.GetBox(result.BoxID)
+	if err != nil {
+		t.Fatalf("GetBox after job returned error: %v", err)
+	}
+	if updated.Files[0].Thumbnail != "" {
+		t.Fatalf("thumbnail was generated for trouble box: %+v", updated.Files[0])
+	}
+}
+
 func TestCreateTextThumbnailRendersMarkdownAsJPEG(t *testing.T) {
 	data, err := createTextThumbnail(services.File{
 		Name:        "notes.md",
--- a/backend/libs/services/resumable.go
+++ b/backend/libs/services/resumable.go
@@ -369,19 +369,20 @@ func (s *UploadService) FinalizeProcessingResumableSession(ctx context.Context,
 	}
 	backend, err := s.storage.Backend(box.StorageBackendID)
 	if err != nil {
+		_ = s.markProcessingBoxFailed(box, err)
 		return UploadResult{}, err
 	}
 	for i, incoming := range staged {
 		source, err := incoming.Open()
 		if err != nil {
+			_ = s.markProcessingBoxFailed(box, err)
 			return UploadResult{}, err
 		}
 		file := box.Files[i]
 		if err := s.writeUploadedObject(ctx, backend, file.ObjectKey, source, incoming.Size(), 0, incoming.ContentType()); err != nil {
 			source.Close()
 			_ = backend.Delete(context.Background(), file.ObjectKey)
-			box.Files[i].ProcessingError = err.Error()
-			_ = s.saveBoxRecord(box)
+			_ = s.markProcessingBoxFailed(box, err)
 			return UploadResult{}, err
 		}
 		source.Close()
@@ -406,6 +407,35 @@ func (s *UploadService) FinalizeProcessingResumableSession(ctx context.Context,
 	return s.resultForBox(box, ""), nil
 }

+func (s *UploadService) markProcessingBoxFailed(box Box, cause error) error {
+	message := "upload processing failed"
+	if cause != nil && strings.TrimSpace(cause.Error()) != "" {
+		message = cause.Error()
+	}
+	s.logger.Warn("resumable upload box marked failed", "source", "user-upload", "severity", "warn", "code", 4021, "box_id", box.ID, "backend_id", s.BoxStorageBackendID(box), "files", len(box.Files), "error", message)
+	now := time.Now().UTC()
+	box.Trouble = true
+	box.TroubleReason = message
+	for i := range box.Files {
+		if box.Files[i].Processing || box.Files[i].ProcessingError == "" {
+			box.Files[i].Processing = false
+			box.Files[i].ProcessingError = message
+			if box.Files[i].UploadedAt.IsZero() {
+				box.Files[i].UploadedAt = now
+			}
+		}
+	}
+	if err := s.saveBoxRecord(box); err != nil {
+		s.logger.Warn("failed to save failed upload box state", "source", "user-upload", "severity", "warn", "code", 4022, "box_id", box.ID, "backend_id", s.BoxStorageBackendID(box), "error", err.Error())
+		return err
+	}
+	if err := s.writeBoxMetadata(box); err != nil {
+		s.logger.Warn("failed to write failed upload box metadata", "source", "user-upload", "severity", "warn", "code", 4023, "box_id", box.ID, "backend_id", s.BoxStorageBackendID(box), "error", err.Error())
+		return err
+	}
+	return nil
+}
+
 func (s *UploadService) CompleteUploadedResumableSession(ctx context.Context, sessionID string) (UploadResult, ResumableSession, error) {
 	session, err := s.GetResumableSession(sessionID)
 	if err != nil {
--- a/backend/libs/services/storage_s3.go
+++ b/backend/libs/services/storage_s3.go
@@ -35,26 +35,35 @@ func (b *s3StorageBackend) ID() string   { return b.cfg.ID }
 func (b *s3StorageBackend) Type() string { return StorageBackendS3 }

 func (b *s3StorageBackend) Put(ctx context.Context, key string, body io.Reader, size int64, contentType string) error {
+	cleanKey := cleanObjectKey(key)
 	opts := minio.PutObjectOptions{ContentType: contentType}
-	_, err := b.client.PutObject(ctx, b.cfg.Bucket, cleanObjectKey(key), body, size, opts)
-	return err
+	_, err := b.client.PutObject(ctx, b.cfg.Bucket, cleanKey, body, size, opts)
+	if err != nil {
+		return fmt.Errorf("s3 put object %q in bucket %q failed: %w", cleanKey, b.cfg.Bucket, err)
+	}
+	return nil
 }

 func (b *s3StorageBackend) Get(ctx context.Context, key string) (StorageObject, error) {
-	object, err := b.client.GetObject(ctx, b.cfg.Bucket, cleanObjectKey(key), minio.GetObjectOptions{})
+	cleanKey := cleanObjectKey(key)
+	object, err := b.client.GetObject(ctx, b.cfg.Bucket, cleanKey, minio.GetObjectOptions{})
 	if err != nil {
-		return StorageObject{}, err
+		return StorageObject{}, fmt.Errorf("s3 get object %q from bucket %q failed: %w", cleanKey, b.cfg.Bucket, err)
 	}
 	info, err := object.Stat()
 	if err != nil {
 		object.Close()
-		return StorageObject{}, err
+		return StorageObject{}, fmt.Errorf("s3 stat object %q in bucket %q failed: %w", cleanKey, b.cfg.Bucket, err)
 	}
 	return StorageObject{Key: key, Size: info.Size, ContentType: info.ContentType, ModTime: info.LastModified, Body: object}, nil
 }

 func (b *s3StorageBackend) Delete(ctx context.Context, key string) error {
-	return b.client.RemoveObject(ctx, b.cfg.Bucket, cleanObjectKey(key), minio.RemoveObjectOptions{})
+	cleanKey := cleanObjectKey(key)
+	if err := b.client.RemoveObject(ctx, b.cfg.Bucket, cleanKey, minio.RemoveObjectOptions{}); err != nil {
+		return fmt.Errorf("s3 delete object %q from bucket %q failed: %w", cleanKey, b.cfg.Bucket, err)
+	}
+	return nil
 }

 func (b *s3StorageBackend) DeletePrefix(ctx context.Context, prefix string) error {
@@ -62,7 +71,7 @@ func (b *s3StorageBackend) DeletePrefix(ctx context.Context, prefix string) erro
 	objects := b.client.ListObjects(ctx, b.cfg.Bucket, minio.ListObjectsOptions{Prefix: prefix, Recursive: true})
 	for object := range objects {
 		if object.Err != nil {
-			return object.Err
+			return fmt.Errorf("s3 list prefix %q in bucket %q failed: %w", prefix, b.cfg.Bucket, object.Err)
 		}
 		if err := b.Delete(ctx, object.Key); err != nil {
 			return err
@@ -75,7 +84,7 @@ func (b *s3StorageBackend) Usage(ctx context.Context) (int64, error) {
 	var total int64
 	for object := range b.client.ListObjects(ctx, b.cfg.Bucket, minio.ListObjectsOptions{Recursive: true}) {
 		if object.Err != nil {
-			return 0, object.Err
+			return 0, fmt.Errorf("s3 usage list bucket %q failed: %w", b.cfg.Bucket, object.Err)
 		}
 		total += object.Size
 	}
@@ -85,7 +94,7 @@ func (b *s3StorageBackend) Usage(ctx context.Context) (int64, error) {
 func (b *s3StorageBackend) Test(ctx context.Context) error {
 	exists, err := b.client.BucketExists(ctx, b.cfg.Bucket)
 	if err != nil {
-		return err
+		return fmt.Errorf("s3 bucket check for %q failed: %w", b.cfg.Bucket, err)
 	}
 	if !exists {
 		return fmt.Errorf("bucket %q does not exist", b.cfg.Bucket)
--- a/backend/libs/services/upload.go
+++ b/backend/libs/services/upload.go
@@ -117,6 +117,8 @@ type Box struct {
 	Obfuscate        bool      `json:"obfuscate"`
 	CreatorIP        string    `json:"creatorIp,omitempty"`
 	StorageBackendID string    `json:"storageBackendId,omitempty"`
+	Trouble          bool      `json:"trouble,omitempty"`
+	TroubleReason    string    `json:"troubleReason,omitempty"`
 	Files            []File    `json:"files"`
 }

@@ -139,6 +141,37 @@ type File struct {
 	UploadedAt              time.Time `json:"uploadedAt"`
 }

+func BoxHasTrouble(box Box) bool {
+	if box.Trouble || strings.TrimSpace(box.TroubleReason) != "" {
+		return true
+	}
+	for _, file := range box.Files {
+		if FileHasTrouble(file) {
+			return true
+		}
+	}
+	return false
+}
+
+func BoxTroubleReason(box Box) string {
+	if strings.TrimSpace(box.TroubleReason) != "" {
+		return box.TroubleReason
+	}
+	for _, file := range box.Files {
+		if strings.TrimSpace(file.ProcessingError) != "" {
+			return file.ProcessingError
+		}
+	}
+	if box.Trouble {
+		return "box has failed processing"
+	}
+	return ""
+}
+
+func FileHasTrouble(file File) bool {
+	return strings.TrimSpace(file.ProcessingError) != ""
+}
+
 type UploadResult struct {
 	BoxID        string       `json:"boxId"`
 	BoxURL       string       `json:"boxUrl"`
--- a/backend/libs/services/upload_test.go
+++ b/backend/libs/services/upload_test.go
@@ -230,6 +230,47 @@ func TestResumableCompleteRejectsMissingChunks(t *testing.T) {
 	}
 }

+func TestProcessingResumableFailureMarksBoxFailed(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{{
+		Name:        "note.txt",
+		Size:        4,
+		ContentType: "text/plain",
+	}}, UploadOptions{MaxDays: 1, StorageBackendID: "missing"}, 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("note")); err != nil {
+		t.Fatalf("PutResumableChunk returned error: %v", err)
+	}
+	result, processing, err := service.CreateProcessingBoxFromResumable(session.ID)
+	if err != nil {
+		t.Fatalf("CreateProcessingBoxFromResumable returned error: %v", err)
+	}
+	if processing.Status != ResumableStatusProcessing {
+		t.Fatalf("session status = %q, want processing", processing.Status)
+	}
+	if _, err := service.FinalizeProcessingResumableSession(testContext(), session.ID); err == nil {
+		t.Fatalf("FinalizeProcessingResumableSession accepted missing backend")
+	}
+	box := getTestBox(t, service, result.BoxID)
+	if len(box.Files) != 1 {
+		t.Fatalf("box files = %+v", box.Files)
+	}
+	if box.Files[0].Processing {
+		t.Fatalf("failed file is still marked processing: %+v", box.Files[0])
+	}
+	if box.Files[0].ProcessingError == "" {
+		t.Fatalf("failed file did not store processing error: %+v", box.Files[0])
+	}
+	if !box.Trouble {
+		t.Fatalf("failed box was not marked as trouble: %+v", box)
+	}
+	if box.TroubleReason == "" {
+		t.Fatalf("failed box did not store trouble reason: %+v", box)
+	}
+}
+
 func TestResumablePartialCompleteKeepsOnlyFinishedFiles(t *testing.T) {
 	service := newTestUploadService(t)
 	session, err := service.CreateResumableSession([]ResumableFileInput{
--- a/backend/static/css/19-popups.css
+++ b/backend/static/css/19-popups.css
@@ -0,0 +1,173 @@
+.warpbox-popups {
+  position: fixed;
+  z-index: 120;
+  inset-block-start: calc(1rem + env(safe-area-inset-top));
+  inset-inline-end: calc(1rem + env(safe-area-inset-right));
+  width: min(26rem, calc(100vw - 2rem));
+  display: grid;
+  gap: 0.75rem;
+  pointer-events: none;
+}
+
+.warpbox-popup {
+  pointer-events: auto;
+  border: 1px solid var(--border);
+  border-radius: calc(var(--radius) - 0.25rem);
+  background: color-mix(in srgb, var(--card) 96%, transparent);
+  color: var(--card-foreground);
+  box-shadow: var(--shadow);
+  opacity: 0;
+  transform: translateY(-0.55rem);
+  transition: opacity 160ms ease, transform 160ms ease;
+  overflow: hidden;
+}
+
+.warpbox-popup.is-visible {
+  opacity: 1;
+  transform: translateY(0);
+}
+
+.warpbox-popup-chrome {
+  display: grid;
+  grid-template-columns: auto minmax(0, 1fr) auto;
+  gap: 0.85rem;
+  align-items: start;
+  padding: 0.95rem;
+}
+
+.warpbox-popup-icon {
+  width: 1.6rem;
+  height: 1.6rem;
+  display: grid;
+  place-items: center;
+  border-radius: 999px;
+  background: color-mix(in srgb, var(--primary) 20%, transparent);
+  color: var(--primary);
+  font-weight: 800;
+  line-height: 1;
+}
+
+.warpbox-popup-warning .warpbox-popup-icon {
+  background: color-mix(in srgb, var(--primary) 26%, transparent);
+  color: var(--primary-hover);
+}
+
+.warpbox-popup-error .warpbox-popup-icon {
+  background: color-mix(in srgb, var(--danger) 18%, transparent);
+  color: var(--danger);
+}
+
+.warpbox-popup-title {
+  display: block;
+  margin: 0 0 0.18rem;
+  font-size: 0.92rem;
+  line-height: 1.2;
+}
+
+.warpbox-popup-message {
+  margin: 0;
+  color: var(--muted-foreground);
+  font-size: 0.84rem;
+  line-height: 1.45;
+  overflow-wrap: anywhere;
+}
+
+.warpbox-popup-close {
+  min-height: 1.8rem;
+  width: 1.8rem;
+  padding: 0;
+  border-color: var(--border);
+  color: var(--muted-foreground);
+  background: var(--surface-1);
+  font-size: 1rem;
+  line-height: 1;
+}
+
+.warpbox-popup-close:hover {
+  color: var(--foreground);
+  background: var(--surface-1-hover);
+}
+
+.warpbox-popup-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 0.55rem;
+  padding: 0 0.95rem 0.95rem;
+}
+
+:root[data-theme="retro"] .warpbox-popups {
+  inset-block-start: 2.65rem;
+  font-family: "PixeloidSans", "PixelOperator", "Microsoft Sans Serif", Tahoma, sans-serif;
+}
+
+:root[data-theme="retro"] .warpbox-popup {
+  border: 1px solid #000000;
+  background: #c0c0c0;
+  color: #000000;
+  box-shadow: inset -1px -1px 0 #404040, inset 1px 1px 0 #ffffff, inset -2px -2px 0 #808080, inset 2px 2px 0 #dfdfdf, 3px 3px 0 rgba(0, 0, 0, 0.45);
+}
+
+:root[data-theme="retro"] .warpbox-popup::before {
+  content: "Warpbox";
+  display: block;
+  margin: 0.18rem 0.18rem 0;
+  padding: 0.22rem 0.35rem;
+  background: linear-gradient(to right, #000078, 80%, #0f80cd);
+  color: #ffffff;
+  font-size: 0.78rem;
+  font-weight: 700;
+}
+
+:root[data-theme="retro"] .warpbox-popup-error::before {
+  content: "Warpbox - Error";
+}
+
+:root[data-theme="retro"] .warpbox-popup-warning::before {
+  content: "Warpbox - Warning";
+}
+
+:root[data-theme="retro"] .warpbox-popup-info::before {
+  content: "Warpbox - Info";
+}
+
+:root[data-theme="retro"] .warpbox-popup-chrome {
+  padding: 0.8rem;
+}
+
+:root[data-theme="retro"] .warpbox-popup-icon {
+  border: 1px solid #000000;
+  background: #ffffff;
+  color: #000078;
+  box-shadow: inset 1px 1px 0 #808080, inset -1px -1px 0 #ffffff;
+}
+
+:root[data-theme="retro"] .warpbox-popup-warning .warpbox-popup-icon {
+  color: #9a5b00;
+}
+
+:root[data-theme="retro"] .warpbox-popup-error .warpbox-popup-icon {
+  color: #c00000;
+}
+
+:root[data-theme="retro"] .warpbox-popup-message {
+  color: #000000;
+}
+
+:root[data-theme="retro"] .warpbox-popup-close {
+  width: 1.45rem;
+  height: 1.25rem;
+  min-height: 1.25rem;
+  background: #c0c0c0;
+  color: #000000;
+  border: 1px solid #000000;
+  box-shadow: inset -1px -1px 0 #404040, inset 1px 1px 0 #ffffff, inset -2px -2px 0 #808080, inset 2px 2px 0 #dfdfdf;
+  font-size: 0.78rem;
+  font-weight: 700;
+}
+
+@media (max-width: 640px) {
+  .warpbox-popups {
+    inset-inline: 1rem;
+    width: auto;
+  }
+}
--- a/backend/static/css/20-upload.css
+++ b/backend/static/css/20-upload.css
@@ -56,6 +56,10 @@
  display: none !important;
 }

+.install-pwa-button[hidden] {
+  display: none !important;
+}
+
 .hero-copy {
  text-align: center;
 }
@@ -395,6 +399,10 @@ button {
  text-align: right;
 }

+.upload-file-state-shared {
+  color: var(--primary);
+}
+
 .upload-recovery-overlay {
  position: fixed;
  inset: 0;
--- a/backend/static/css/30-download.css
+++ b/backend/static/css/30-download.css
@@ -698,6 +698,12 @@
  text-decoration: none;
 }

+.button.is-disabled {
+  opacity: .62;
+  cursor: not-allowed;
+  pointer-events: none;
+}
+
 .upload-processing-alert {
  margin: 1rem 0;
  padding: .85rem 1rem;
@@ -707,6 +713,11 @@
  color: var(--foreground);
 }

+.upload-processing-alert-error {
+  border-color: color-mix(in srgb, var(--danger) 55%, transparent);
+  background: color-mix(in srgb, var(--danger) 14%, transparent);
+}
+
 .thumb-link {
  flex: 0 0 4.75rem;
  width: 4.75rem;
@@ -870,6 +881,24 @@
  cursor: wait;
 }

+.file-card.is-failed {
+  border-color: color-mix(in srgb, var(--danger) 55%, var(--border));
+  background: color-mix(in srgb, var(--danger) 8%, var(--background));
+}
+
+.file-card.is-failed .file-open {
+  cursor: not-allowed;
+}
+
+.file-error {
+  display: block;
+  max-width: 100%;
+  margin-top: 0.18rem;
+  color: var(--danger);
+  white-space: normal;
+  overflow-wrap: anywhere;
+}
+
 .file-reaction-dock {
  position: static;
  z-index: 2;
--- a/backend/static/js/02-pwa.js
+++ b/backend/static/js/02-pwa.js
@@ -0,0 +1,43 @@
+(function () {
+  let installPrompt = null;
+
+  if ("serviceWorker" in navigator) {
+    window.addEventListener("load", () => {
+      navigator.serviceWorker.register("/service-worker.js").catch(() => {
+        /* Service workers are progressive enhancement here. */
+      });
+    });
+  }
+
+  window.addEventListener("beforeinstallprompt", (event) => {
+    const button = document.querySelector("[data-install-pwa]");
+    if (!button) {
+      return;
+    }
+    event.preventDefault();
+    installPrompt = event;
+    button.hidden = false;
+    button.addEventListener("click", async () => {
+      if (!installPrompt) {
+        return;
+      }
+      button.disabled = true;
+      try {
+        await installPrompt.prompt();
+        await installPrompt.userChoice;
+      } finally {
+        installPrompt = null;
+        button.hidden = true;
+        button.disabled = false;
+      }
+    }, { once: true });
+  });
+
+  window.addEventListener("appinstalled", () => {
+    const button = document.querySelector("[data-install-pwa]");
+    if (button) {
+      button.hidden = true;
+    }
+    installPrompt = null;
+  });
+})();
--- a/backend/static/js/03-popups.js
+++ b/backend/static/js/03-popups.js
@@ -0,0 +1,174 @@
+(function () {
+  const DEFAULT_DURATION = 6200;
+  const VARIANTS = ["info", "warning", "error"];
+  const GENERIC_ERROR_MESSAGE = "Something went wrong on this page. Please try again in a moment.";
+
+  window.Warpbox = window.Warpbox || {};
+  let lastGlobalErrorAt = 0;
+
+  function ensureRegion() {
+    let region = document.querySelector("[data-warpbox-popups]");
+    if (region) {
+      return region;
+    }
+    region = document.createElement("div");
+    region.className = "warpbox-popups";
+    region.setAttribute("data-warpbox-popups", "");
+    region.setAttribute("aria-live", "polite");
+    region.setAttribute("aria-atomic", "false");
+    document.body.append(region);
+    return region;
+  }
+
+  function normalizeOptions(options, message) {
+    if (typeof options === "string") {
+      options = { message: options };
+    } else {
+      options = options || {};
+    }
+    if (message) {
+      options.message = message;
+    }
+    const variant = VARIANTS.includes(options.variant) ? options.variant : "info";
+    return {
+      variant,
+      title: options.title || defaultTitle(variant),
+      message: options.message || "",
+      duration: Number.isFinite(options.duration) ? options.duration : DEFAULT_DURATION,
+      actions: Array.isArray(options.actions) ? options.actions : [],
+    };
+  }
+
+  function defaultTitle(variant) {
+    if (variant === "error") {
+      return "Error";
+    }
+    if (variant === "warning") {
+      return "Warning";
+    }
+    return "Info";
+  }
+
+  function notify(options, message) {
+    const config = normalizeOptions(options, message);
+    const region = ensureRegion();
+    const popup = document.createElement("section");
+    popup.className = "warpbox-popup warpbox-popup-" + config.variant;
+    popup.setAttribute("role", config.variant === "error" ? "alert" : "status");
+
+    const chrome = document.createElement("div");
+    chrome.className = "warpbox-popup-chrome";
+
+    const icon = document.createElement("span");
+    icon.className = "warpbox-popup-icon";
+    icon.setAttribute("aria-hidden", "true");
+    icon.textContent = config.variant === "error" ? "!" : config.variant === "warning" ? "?" : "i";
+
+    const body = document.createElement("div");
+    body.className = "warpbox-popup-body";
+
+    const title = document.createElement("strong");
+    title.className = "warpbox-popup-title";
+    title.textContent = config.title;
+
+    const text = document.createElement("p");
+    text.className = "warpbox-popup-message";
+    text.textContent = config.message;
+
+    body.append(title, text);
+
+    const close = document.createElement("button");
+    close.type = "button";
+    close.className = "warpbox-popup-close";
+    close.setAttribute("aria-label", "Dismiss notification");
+    close.textContent = "x";
+    close.addEventListener("click", () => dismiss(popup));
+
+    chrome.append(icon, body, close);
+    popup.append(chrome);
+
+    if (config.actions.length > 0) {
+      const actions = document.createElement("div");
+      actions.className = "warpbox-popup-actions";
+      config.actions.forEach((action) => {
+        const button = document.createElement("button");
+        button.type = "button";
+        button.className = "button " + (action.kind === "primary" ? "button-primary" : "button-outline");
+        button.textContent = action.label || "Action";
+        button.addEventListener("click", () => {
+          if (typeof action.onClick === "function") {
+            action.onClick();
+          }
+          if (action.dismiss !== false) {
+            dismiss(popup);
+          }
+        });
+        actions.append(button);
+      });
+      popup.append(actions);
+    }
+
+    region.append(popup);
+    window.requestAnimationFrame(() => popup.classList.add("is-visible"));
+
+    let timer = null;
+    if (config.duration > 0) {
+      timer = window.setTimeout(() => dismiss(popup), config.duration);
+    }
+
+    return {
+      element: popup,
+      close: function closePopup() {
+        if (timer) {
+          window.clearTimeout(timer);
+        }
+        dismiss(popup);
+      },
+    };
+  }
+
+  function dismiss(popup) {
+    if (!popup || popup.dataset.closing === "true") {
+      return;
+    }
+    popup.dataset.closing = "true";
+    popup.classList.remove("is-visible");
+    window.setTimeout(() => popup.remove(), 180);
+  }
+
+  window.Warpbox.notify = notify;
+  window.Warpbox.info = function info(message, options) {
+    return notify({ ...(options || {}), variant: "info", message });
+  };
+  window.Warpbox.warning = function warning(message, options) {
+    return notify({ ...(options || {}), variant: "warning", message });
+  };
+  window.Warpbox.error = function error(message, options) {
+    return notify({ ...(options || {}), variant: "error", message });
+  };
+
+  function showGlobalError() {
+    const now = Date.now();
+    if (now - lastGlobalErrorAt < 2500) {
+      return;
+    }
+    lastGlobalErrorAt = now;
+    notify({
+      variant: "error",
+      title: "Page error",
+      message: GENERIC_ERROR_MESSAGE,
+      duration: 9000,
+    });
+  }
+
+  window.addEventListener("error", function (event) {
+    if (event && event.target && event.target !== window) {
+      return;
+    }
+    showGlobalError();
+  });
+
+  window.addEventListener("unhandledrejection", function () {
+    showGlobalError();
+  });
+})();
--- a/backend/static/js/40-upload.js
+++ b/backend/static/js/40-upload.js
@@ -15,6 +15,8 @@
  const manageLink = document.querySelector("#manage-link");
  const newUpload = document.querySelector("#new-upload");
  const RESUMABLE_SESSIONS_KEY = "warpbox-resumable-sessions";
+  const SHARE_CACHE = "warpbox-share-target-v1";
+  const SHARE_LATEST_KEY = "/__warpbox_share_target__/latest";

  if (!form || !dropZone || !fileInput) {
    return;
@@ -47,6 +49,9 @@
  let uploadLocked = false;
  let recoveredDraft = null;
  let resumeMode = false;
+  let sharedTargetDraft = null;
+  const maxUploadBytes = parseInt(form.dataset.maxUploadBytes || "-1", 10);
+  const maxUploadLabel = form.dataset.maxUploadLabel || (maxUploadBytes > 0 && window.Warpbox.formatBytes ? window.Warpbox.formatBytes(maxUploadBytes) : "the configured limit");

  ["dragenter", "dragover"].forEach((eventName) => {
    dropZone.addEventListener(eventName, (event) => {
@@ -93,6 +98,12 @@
    event.preventDefault();
    if (selectedFiles.length === 0) {
      updateStatus("Choose at least one file first.");
+      notify("warning", "Choose at least one file first.", {
+        title: "No files selected",
+      });
+      return;
+    }
+    if (!validateSelectedFilesWithinLimit(selectedFiles)) {
      return;
    }

@@ -108,8 +119,10 @@
    try {
      const payload = await uploadResumable(form.action, formData, selectedFiles);
      renderResult(payload);
+      await clearSharedTargetPayload();
      form.reset();
      selectedFiles = [];
+      sharedTargetDraft = null;
      resumeMode = false;
      recoveredDraft = null;
      fileInput.value = "";
@@ -123,6 +136,7 @@
      }
    } catch (error) {
      updateStatus(error.message || "Upload failed");
+      notifyUploadError(error);
    } finally {
      setLoading(false, submit);
    }
@@ -136,26 +150,168 @@

  if (newUpload) {
    newUpload.addEventListener("click", () => {
+      if (sharedTargetDraft) {
+        clearSharedTargetPayload().finally(() => resetFreshUploadState());
+        return;
+      }
      cancelRecoveredDraft().catch((error) => {
        updateStatus(error.message || "Upload draft could not be deleted");
      });
    });
  }

+  if (isShareTargetLaunch()) {
+    loadSharedTargetFiles();
+  } else {
    recoverResumableSessions();
+  }

  function addSelectedFiles(files) {
    if (uploadLocked) {
      return;
    }
+    const rejected = [];
    Array.from(files || []).forEach((file) => {
+      if (fileExceedsUploadLimit(file)) {
+        rejected.push(file);
+        return;
+      }
      if (!selectedFiles.some((existing) => fileIdentity(existing) === fileIdentity(file))) {
        selectedFiles.push(file);
      }
    });
+    if (rejected.length > 0) {
+      notifyRejectedFiles(rejected);
+    }
    updateSelectedState();
  }

+  function fileExceedsUploadLimit(file) {
+    return Number.isFinite(maxUploadBytes) && maxUploadBytes > 0 && file && file.size > maxUploadBytes;
+  }
+
+  function validateSelectedFilesWithinLimit(files) {
+    const rejected = Array.from(files || []).filter(fileExceedsUploadLimit);
+    if (rejected.length === 0) {
+      return true;
+    }
+    selectedFiles = selectedFiles.filter((file) => !fileExceedsUploadLimit(file));
+    notifyRejectedFiles(rejected);
+    updateSelectedState();
+    return false;
+  }
+
+  function notifyRejectedFiles(files) {
+    const names = files.slice(0, 3).map((file) => `"${file.name}" (${window.Warpbox.formatBytes(file.size)})`).join(", ");
+    const extra = files.length > 3 ? `, and ${files.length - 3} more` : "";
+    const message = `${names}${extra} ${files.length === 1 ? "is" : "are"} over the ${maxUploadLabel} upload limit.`;
+    updateStatus(message);
+    notify("error", message, {
+      title: "Upload limit exceeded",
+      duration: 9000,
+    });
+  }
+
+  function notifyUploadError(error) {
+    const message = error && error.message ? error.message : "Upload failed";
+    const lower = message.toLowerCase();
+    const isLimit = lower.includes("limit") || lower.includes("quota") || lower.includes("too large") || lower.includes("exceeds");
+    notify("error", message, {
+      title: isLimit ? "Upload limit reached" : "Upload failed",
+      duration: isLimit ? 9000 : 7200,
+    });
+  }
+
+  function notify(variant, message, options) {
+    if (window.Warpbox && typeof window.Warpbox.notify === "function") {
+      window.Warpbox.notify({ ...(options || {}), variant, message });
+    }
+  }
+
+  function isShareTargetLaunch() {
+    const params = new URLSearchParams(window.location.search || "");
+    return params.has("share-target");
+  }
+
+  async function loadSharedTargetFiles() {
+    if (!("caches" in window) || typeof File === "undefined") {
+      updateStatus("Shared files could not be loaded in this browser.");
+      recoverResumableSessions();
+      return;
+    }
+    updateStatus("Loading shared files...");
+    try {
+      const cache = await caches.open(SHARE_CACHE);
+      const metadataResponse = await cache.match(SHARE_LATEST_KEY);
+      if (!metadataResponse) {
+        updateStatus(new URLSearchParams(window.location.search).get("share-target") === "unsupported"
+          ? "Install Warpbox as an app to share files into it from your device."
+          : "No shared files were found.");
+        recoverResumableSessions();
+        return;
+      }
+      const metadata = await metadataResponse.json();
+      if (metadata.error) {
+        updateStatus(metadata.error);
+        recoverResumableSessions();
+        return;
+      }
+      const files = [];
+      for (const item of metadata.files || []) {
+        if (!item.key) {
+          continue;
+        }
+        const response = await cache.match(item.key);
+        if (!response) {
+          continue;
+        }
+        const blob = await response.blob();
+        files.push(new File([blob], item.name || "shared-file", {
+          type: item.type || blob.type || "application/octet-stream",
+          lastModified: item.lastModified || Date.now(),
+        }));
+      }
+      sharedTargetDraft = metadata;
+      selectedFiles = files;
+      resumeMode = false;
+      recoveredDraft = null;
+      validateSelectedFilesWithinLimit(selectedFiles);
+      if (selectedFiles.length > 0) {
+        renderQueue(selectedFiles, "queued", { shared: true });
+        updateStatus("Shared files ready.");
+      } else {
+        updateStatus("No files were included in this share.");
+      }
+      updateSelectedState();
+    } catch (error) {
+      updateStatus(error.message || "Shared files could not be loaded.");
+      recoverResumableSessions();
+    }
+  }
+
+  async function clearSharedTargetPayload() {
+    const draft = sharedTargetDraft;
+    sharedTargetDraft = null;
+    if (!draft || !("caches" in window)) {
+      sharedTargetDraft = null;
+      return;
+    }
+    try {
+      const cache = await caches.open(SHARE_CACHE);
+      for (const item of draft.files || []) {
+        if (item.key) {
+          await cache.delete(item.key);
+        }
+      }
+      if (draft.id) {
+        await cache.delete("/__warpbox_share_target__/meta/" + encodeURIComponent(draft.id));
+      }
+      await cache.delete(SHARE_LATEST_KEY);
+    } catch (error) {
+      /* ignore cache cleanup failures */
+    }
+  }
+
  function removeSelectedFile(index) {
    if (uploadLocked) {
      return;
@@ -175,12 +331,18 @@
        fileSummary.textContent = count === 0
          ? "Reselect missing files to resume, or add extra files to this upload."
          : `${count} local file${count === 1 ? "" : "s"} ready for the recovered upload.`;
+      } else if (sharedTargetDraft) {
+        fileSummary.textContent = count === 0
+          ? "No shared files were received."
+          : `${count} shared file${count === 1 ? "" : "s"} ready. Review options, then upload.`;
      } else {
        fileSummary.textContent = count === 0 ? "Choose one or more files to begin." : `${count} file${count === 1 ? "" : "s"} ready.`;
      }
    }
    if (resumeMode && recoveredDraft) {
      renderResumeQueue(recoveredDraft.session, selectedFiles);
+    } else if (sharedTargetDraft && count > 0) {
+      renderQueue(selectedFiles, "queued", { shared: true });
    } else if (count > 0) {
      renderQueue(selectedFiles, "queued");
    } else if (uploadQueue) {
@@ -194,7 +356,7 @@
    if (!newUpload) {
      return;
    }
-    const visible = Boolean(resumeMode && recoveredDraft);
+    const visible = Boolean((resumeMode && recoveredDraft) || sharedTargetDraft);
    newUpload.hidden = !visible;
    newUpload.style.display = visible ? "" : "none";
  }
@@ -803,6 +965,7 @@
    selectedFiles = [];
    resumeMode = false;
    recoveredDraft = null;
+    sharedTargetDraft = null;
    fileInput.value = "";
    result.hidden = true;
    if (resultList) {
@@ -913,20 +1076,22 @@
    return Math.max(0, Math.min(100, Math.round((bytes / total) * 100)));
  }

-  function renderQueue(files, status) {
+  function renderQueue(files, status, options) {
    if (!uploadQueue) {
      return;
    }
+    const shared = Boolean(options && options.shared);
    uploadQueue.hidden = files.length === 0;
    uploadQueue.replaceChildren();
    files.forEach((file, index) => {
      uploadQueue.append(createFileRow({
        name: file.name,
-        meta: window.Warpbox.formatBytes(file.size),
+        meta: shared ? `${window.Warpbox.formatBytes(file.size)} · Shared from device` : window.Warpbox.formatBytes(file.size),
        progress: status === "queued" ? 0 : 100,
        status,
        index,
        removable: status === "queued",
+        shared,
      }));
    });
  }
@@ -965,6 +1130,12 @@
      badge.textContent = "Needs local file";
      side.append(badge);
    }
+    if (file.shared) {
+      const badge = document.createElement("small");
+      badge.className = "upload-file-state upload-file-state-shared";
+      badge.textContent = "Shared from device";
+      side.append(badge);
+    }
    if (file.removable) {
      const remove = document.createElement("button");
      remove.className = "upload-file-remove";
--- a/backend/static/js/service-worker.js
+++ b/backend/static/js/service-worker.js
@@ -0,0 +1,110 @@
+self.addEventListener("fetch", (event) => {
+  const url = new URL(event.request.url);
+  if (event.request.method === "POST" && url.origin === self.location.origin && url.pathname === "/share-target") {
+    event.respondWith(handleShareTarget(event.request));
+  }
+});
+
+const SHARE_CACHE = "warpbox-share-target-v1";
+const SHARE_PREFIX = "/__warpbox_share_target__/";
+const LATEST_KEY = SHARE_PREFIX + "latest";
+
+async function handleShareTarget(request) {
+  const id = Date.now().toString(36) + "-" + Math.random().toString(36).slice(2, 10);
+  try {
+    const formData = await request.formData();
+    const files = collectSharedFiles(formData);
+    const cache = await caches.open(SHARE_CACHE);
+    const metadata = {
+      id,
+      title: stringValue(formData.get("title")),
+      text: stringValue(formData.get("text")),
+      url: stringValue(formData.get("url")),
+      createdAt: new Date().toISOString(),
+      files: [],
+    };
+
+    await deletePreviousShare(cache);
+    for (let index = 0; index < files.length; index += 1) {
+      const file = files[index];
+      const key = SHARE_PREFIX + "file/" + encodeURIComponent(id) + "/" + index;
+      metadata.files.push({
+        key,
+        name: file.name || "shared-file",
+        type: file.type || "application/octet-stream",
+        size: file.size || 0,
+        lastModified: file.lastModified || Date.now(),
+      });
+      await cache.put(key, new Response(file, {
+        headers: {
+          "Content-Type": file.type || "application/octet-stream",
+          "Cache-Control": "no-store",
+        },
+      }));
+    }
+
+    await cache.put(LATEST_KEY, jsonResponse(metadata));
+    await cache.put(SHARE_PREFIX + "meta/" + encodeURIComponent(id), jsonResponse(metadata));
+  } catch (error) {
+    await storeShareError(id, error);
+  }
+
+  return Response.redirect("/?share-target=1&share-id=" + encodeURIComponent(id), 303);
+}
+
+function collectSharedFiles(formData) {
+  const files = [];
+  ["files", "file", "sharex"].forEach((name) => {
+    formData.getAll(name).forEach((value) => {
+      if (value instanceof File && value.size > 0) {
+        files.push(value);
+      }
+    });
+  });
+  return files;
+}
+
+function stringValue(value) {
+  return typeof value === "string" ? value : "";
+}
+
+function jsonResponse(payload) {
+  return new Response(JSON.stringify(payload), {
+    headers: {
+      "Content-Type": "application/json",
+      "Cache-Control": "no-store",
+    },
+  });
+}
+
+async function storeShareError(id, error) {
+  const cache = await caches.open(SHARE_CACHE);
+  await cache.put(LATEST_KEY, jsonResponse({
+    id,
+    error: error && error.message ? error.message : "Shared files could not be staged.",
+    createdAt: new Date().toISOString(),
+    files: [],
+  }));
+}
+
+async function deletePreviousShare(cache) {
+  const previous = await cache.match(LATEST_KEY);
+  if (!previous) {
+    return;
+  }
+  let metadata = null;
+  try {
+    metadata = await previous.json();
+  } catch (error) {
+    metadata = null;
+  }
+  for (const file of metadata && metadata.files ? metadata.files : []) {
+    if (file.key) {
+      await cache.delete(file.key);
+    }
+  }
+  if (metadata && metadata.id) {
+    await cache.delete(SHARE_PREFIX + "meta/" + encodeURIComponent(metadata.id));
+  }
+  await cache.delete(LATEST_KEY);
+}
--- a/backend/static/site.webmanifest
+++ b/backend/static/site.webmanifest
@@ -7,6 +7,22 @@
  "display": "standalone",
  "background_color": "#0b0b16",
  "theme_color": "#8b5cf6",
+  "share_target": {
+    "action": "/share-target",
+    "method": "POST",
+    "enctype": "multipart/form-data",
+    "params": {
+      "title": "title",
+      "text": "text",
+      "url": "url",
+      "files": [
+        {
+          "name": "files",
+          "accept": ["*/*"]
+        }
+      ]
+    }
+  },
  "icons": [
    {
      "src": "/static/android-chrome-192x192.png",
--- a/backend/templates/layouts/base.html
+++ b/backend/templates/layouts/base.html
@@ -59,6 +59,7 @@
  <link rel="stylesheet" href="/static/css/16-retro.css?version={{.AppVersion}}">
  <link rel="stylesheet" href="/static/css/17-gruvbox.css?version={{.AppVersion}}">
  <link rel="stylesheet" href="/static/css/18-cyberpunk.css?version={{.AppVersion}}">
+  <link rel="stylesheet" href="/static/css/19-popups.css?version={{.AppVersion}}">
  <link rel="stylesheet" href="/static/css/20-upload.css?version={{.AppVersion}}">
  <link rel="stylesheet" href="/static/css/30-download.css?version={{.AppVersion}}">
  <link rel="stylesheet" href="/static/css/40-docs.css?version={{.AppVersion}}">
@@ -67,6 +68,8 @@
  <link rel="stylesheet" href="/static/css/70-tokens.css?version={{.AppVersion}}">
  <link rel="stylesheet" href="/static/css/90-responsive.css?version={{.AppVersion}}">
  <script defer src="/static/js/00-utils.js?version={{.AppVersion}}"></script>
+  <script defer src="/static/js/02-pwa.js?version={{.AppVersion}}"></script>
+  <script defer src="/static/js/03-popups.js?version={{.AppVersion}}"></script>
  <script defer src="/static/js/10-file-browser.js?version={{.AppVersion}}"></script>
  <script defer src="/static/js/12-reactions.js?version={{.AppVersion}}"></script>
  <script defer src="/static/js/20-storage-admin.js?version={{.AppVersion}}"></script>
--- a/backend/templates/pages/download.html
+++ b/backend/templates/pages/download.html
@@ -25,11 +25,17 @@

      {{if .Data.Files}}
        {{$processing := false}}{{range .Data.Files}}{{if .Processing}}{{$processing = true}}{{end}}{{end}}
+        {{$failed := false}}{{range .Data.Files}}{{if .Failed}}{{$failed = true}}{{end}}{{end}}
        {{if $processing}}
          <div class="upload-processing-alert" role="status">
            Some files are still processing. You can share this link now, but processing files will become available shortly.
          </div>
        {{end}}
+        {{if $failed}}
+          <div class="upload-processing-alert upload-processing-alert-error" role="alert">
+            Upload processing failed for one or more files. The original upload could not be finalized by the storage backend.
+          </div>
+        {{end}}
        {{$single := eq (len .Data.Files) 1}}
        <div class="badge-row">
          <span class="badge badge-expiry">Expires {{.Data.ExpiresLabel}}</span>
@@ -37,6 +43,11 @@
        </div>

        {{if not .Data.Locked}}
+          {{if or $processing $failed}}
+            <span class="button button-outline button-wide is-disabled" aria-disabled="true">
+              {{if $failed}}Download unavailable{{else}}Files processing{{end}}
+            </span>
+          {{else}}
          {{if $single}}
            {{$first := index .Data.Files 0}}
            <a class="button button-primary button-wide" href="{{$first.DownloadURL}}" download="{{$first.Name}}">
@@ -50,6 +61,7 @@
            </a>
          {{end}}
          {{end}}
+        {{end}}

        <div class="file-browser-window" data-file-browser-window>
          <div class="file-browser-titlebar">
@@ -80,8 +92,8 @@
          </div>
          <div class="download-list file-browser is-thumbs" data-file-browser>
            {{range .Data.Files}}
-              <article class="download-item file-card {{if .Processing}}is-processing{{end}}" data-kind="{{.PreviewKind}}" {{if not .Processing}}data-file-context data-preview-url="{{.URL}}" data-view-url="{{.DownloadURL}}?inline=1" data-download-url="{{.DownloadURL}}"{{end}} data-file-name="{{.Name}}" data-reaction-card data-react-url="{{.ReactURL}}" data-reacted="{{if .Reacted}}true{{else}}false{{end}}">
-                {{if .Processing}}<div class="file-open" aria-label="{{.Name}} is processing">{{else}}<a class="file-open" href="{{.DownloadURL}}?inline=1"{{if not $single}} target="_blank" rel="noopener noreferrer"{{end}} aria-label="Open {{.Name}}">{{end}}
+              <article class="download-item file-card {{if .Processing}}is-processing{{end}} {{if .Failed}}is-failed{{end}}" data-kind="{{.PreviewKind}}" {{if and (not .Processing) (not .Failed)}}data-file-context data-preview-url="{{.URL}}" data-view-url="{{.DownloadURL}}?inline=1" data-download-url="{{.DownloadURL}}"{{end}} data-file-name="{{.Name}}" data-reaction-card data-react-url="{{.ReactURL}}" data-reacted="{{if .Reacted}}true{{else}}false{{end}}">
+                {{if or .Processing .Failed}}<div class="file-open" aria-label="{{.Name}} {{if .Failed}}failed processing{{else}}is processing{{end}}">{{else}}<a class="file-open" href="{{.DownloadURL}}?inline=1"{{if not $single}} target="_blank" rel="noopener noreferrer"{{end}} aria-label="Open {{.Name}}">{{end}}
                  <span class="file-media">
                    {{if .HasThumbnail}}
                      <img class="file-thumb" src="{{.ThumbnailURL}}" alt="" loading="lazy">
@@ -92,11 +104,12 @@
                  </span>
                  <span class="file-main">
                    <strong class="file-name" title="{{.Name}}">{{.Name}}</strong>
-                    <small>{{.Size}} · {{if .Processing}}Processing{{else}}{{.ContentType}}{{end}}</small>
+                    <small>{{.Size}} · {{if .Failed}}Failed{{else if .Processing}}Processing{{else}}{{.ContentType}}{{end}}</small>
+                    {{if .Failed}}<small class="file-error">{{.Error}}</small>{{end}}
                  </span>
-                  <span class="file-type">{{if .Processing}}Processing{{else}}{{.ContentType}}{{end}}</span>
+                  <span class="file-type">{{if .Failed}}Failed{{else if .Processing}}Processing{{else}}{{.ContentType}}{{end}}</span>
                  <span class="file-size">{{.Size}}</span>
-                {{if .Processing}}</div>{{else}}</a>{{end}}
+                {{if or .Processing .Failed}}</div>{{else}}</a>{{end}}
                {{if not $.Data.Locked}}
                  <div class="file-reaction-dock" data-reaction-dock>
                    <div class="file-reactions" data-reaction-list>
--- a/backend/templates/pages/home.html
+++ b/backend/templates/pages/home.html
@@ -10,7 +10,7 @@
    {{end}}
  </div>

-  <form class="upload-grid" id="upload-form" action="/api/v1/upload" method="post" enctype="multipart/form-data">
+  <form class="upload-grid" id="upload-form" action="/api/v1/upload" method="post" enctype="multipart/form-data" data-max-upload-bytes="{{.Data.MaxUploadBytes}}" data-max-upload-label="{{.Data.MaxUploadSize}}">
    <div class="card upload-main">
      <div class="card-content">
        {{if .CurrentUser}}
@@ -76,6 +76,7 @@

        <div class="form-footer">
          <p id="file-summary">Choose one or more files to begin.</p>
+          <button class="button button-outline install-pwa-button" type="button" data-install-pwa hidden>Install Warpbox</button>
          <button class="button button-primary" type="submit">Upload files</button>
          <button class="button button-danger upload-new-button" type="button" id="new-upload" hidden>New upload</button>
        </div>