fix(handlers): bypass box creation limits for batched uploads

Update `createOrAppendBox` to accept the upload policy and admin status, allowing policy enforcement to be handled during the box creation/append decision process. This ensures that appending files to an existing batch does not incorrectly trigger daily or active box creation limits, as no new box is being created.

Also, add unit tests to verify that batched uploads successfully bypass both daily and active box creation caps.

backend/libs/handlers/upload.go

@@ -121,7 +121,12 @@ func (a *App) Upload(w http.ResponseWriter, r *http.Request) {
 		CreatorIP:         uploadClientIP(r),
 		StorageBackendID:  effectivePolicy.StorageBackendID,
 	}
-	result, boxesAdded, err := a.createOrAppendBox(r, user, loggedIn, files, opts)
+	result, boxesAdded, status, policyMessage, err := a.createOrAppendBox(r, user, loggedIn, effectivePolicy, files, opts, !isAdminUpload)
+	if policyMessage != "" {
+		a.logger.Warn("upload rejected by policy", "source", "quota", "severity", "warn", "code", status, "ip", uploadClientIP(r), "user_id", user.ID, "message", policyMessage, "bytes", totalBytes, "files", len(files))
+		helpers.WriteJSONError(w, status, policyMessage)
+		return
+	}
 	if err != nil {
 		a.logger.Warn("upload failed", "source", "user-upload", "severity", "warn", "code", 4001, "ip", uploadClientIP(r), "user_id", user.ID, "error", err.Error())
 		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
@@ -154,14 +159,19 @@ func (a *App) Upload(w http.ResponseWriter, r *http.Request) {
 // uploadGroupWindow are folded into one box. Without the header the behaviour is
 // identical to creating a fresh box every time. Returns the result and how many
 // boxes were created (1 for a new box, 0 for an append) for usage accounting.
-func (a *App) createOrAppendBox(r *http.Request, user services.User, loggedIn bool, files []*multipart.FileHeader, opts services.UploadOptions) (services.UploadResult, int, error) {
+func (a *App) createOrAppendBox(r *http.Request, user services.User, loggedIn bool, policy services.EffectiveUploadPolicy, files []*multipart.FileHeader, opts services.UploadOptions, enforceBoxLimits bool) (services.UploadResult, int, int, string, error) {
 	batch := strings.TrimSpace(r.Header.Get(uploadBatchHeader))
 	if batch == "" {
+		if enforceBoxLimits {
+			if status, message := a.checkBoxCreationPolicy(r, user, loggedIn, policy); message != "" {
+				return services.UploadResult{}, 0, status, message, nil
+			}
+		}
 		result, err := a.uploadService.CreateBox(files, opts)
 		if err != nil {
-			return services.UploadResult{}, 0, err
+			return services.UploadResult{}, 0, 0, "", err
 		}
-		return result, 1, nil
+		return result, 1, 0, "", nil
 	}
 
 	// Group key is scoped to the uploader so batches never cross accounts/IPs.
@@ -184,20 +194,25 @@ func (a *App) createOrAppendBox(r *http.Request, user services.User, loggedIn bo
 				result.ManageURL = entry.manageURL
 				result.DeleteURL = entry.deleteURL
 				entry.at = time.Now()
-				return result, 0, nil
+				return result, 0, 0, "", nil
 			}
 		}
 	}
 
+	if enforceBoxLimits {
+		if status, message := a.checkBoxCreationPolicy(r, user, loggedIn, policy); message != "" {
+			return services.UploadResult{}, 0, status, message, nil
+		}
+	}
 	result, err := a.uploadService.CreateBox(files, opts)
 	if err != nil {
-		return services.UploadResult{}, 0, err
+		return services.UploadResult{}, 0, 0, "", err
 	}
 	entry.boxID = result.BoxID
 	entry.manageURL = result.ManageURL
 	entry.deleteURL = result.DeleteURL
 	entry.at = time.Now()
-	return result, 1, nil
+	return result, 1, 0, "", nil
 }
 
 // batchBoxMatches guards that a batched append only ever touches a box owned by
@@ -230,16 +245,6 @@ func (a *App) checkUploadPolicy(r *http.Request, user services.User, loggedIn bo
 		if policy.DailyUploadMB > 0 && usage.UploadedBytes+totalBytes > services.MegabytesToBytes(policy.DailyUploadMB) {
 			return http.StatusTooManyRequests, "anonymous daily upload limit reached"
 		}
-		if policy.DailyBoxes > 0 && usage.UploadedBoxes+1 > policy.DailyBoxes {
-			return http.StatusTooManyRequests, "anonymous daily box limit reached"
-		}
-		activeBoxes, err := a.uploadService.ActiveBoxCountForIP(uploadClientIP(r))
-		if err != nil {
-			return http.StatusInternalServerError, "active box limit could not be checked"
-		}
-		if policy.ActiveBoxes > 0 && activeBoxes+1 > policy.ActiveBoxes {
-			return http.StatusTooManyRequests, "anonymous active box limit reached"
-		}
 		if status, message := a.checkStorageBackendCapacity(policy.StorageBackendID, settings, totalBytes); message != "" {
 			return status, message
 		}
@@ -253,16 +258,6 @@ func (a *App) checkUploadPolicy(r *http.Request, user services.User, loggedIn bo
 	if policy.DailyUploadMB > 0 && usage.UploadedBytes+totalBytes > services.MegabytesToBytes(policy.DailyUploadMB) {
 		return http.StatusTooManyRequests, "daily upload limit reached"
 	}
-	if policy.DailyBoxes > 0 && usage.UploadedBoxes+1 > policy.DailyBoxes {
-		return http.StatusTooManyRequests, "daily box limit reached"
-	}
-	activeBoxes, err := a.uploadService.ActiveBoxCountForUser(user.ID)
-	if err != nil {
-		return http.StatusInternalServerError, "active box limit could not be checked"
-	}
-	if policy.ActiveBoxes > 0 && activeBoxes+1 > policy.ActiveBoxes {
-		return http.StatusTooManyRequests, "active box limit reached"
-	}
 	activeStorage, err := a.uploadService.UserActiveStorageUsed(user.ID)
 	if err != nil {
 		return http.StatusInternalServerError, "storage quota could not be checked"
@@ -276,6 +271,42 @@ func (a *App) checkUploadPolicy(r *http.Request, user services.User, loggedIn bo
 	return 0, ""
 }
 
+func (a *App) checkBoxCreationPolicy(r *http.Request, user services.User, loggedIn bool, policy services.EffectiveUploadPolicy) (int, string) {
+	now := time.Now().UTC()
+	if !loggedIn {
+		usage, err := a.settingsService.UsageForIP(uploadClientIP(r), now)
+		if err != nil {
+			return http.StatusInternalServerError, "upload usage could not be checked"
+		}
+		if policy.DailyBoxes > 0 && usage.UploadedBoxes+1 > policy.DailyBoxes {
+			return http.StatusTooManyRequests, "anonymous daily box limit reached"
+		}
+		activeBoxes, err := a.uploadService.ActiveBoxCountForIP(uploadClientIP(r))
+		if err != nil {
+			return http.StatusInternalServerError, "active box limit could not be checked"
+		}
+		if policy.ActiveBoxes > 0 && activeBoxes+1 > policy.ActiveBoxes {
+			return http.StatusTooManyRequests, "anonymous active box limit reached"
+		}
+		return 0, ""
+	}
+	usage, err := a.settingsService.UsageForUser(user.ID, now)
+	if err != nil {
+		return http.StatusInternalServerError, "upload usage could not be checked"
+	}
+	if policy.DailyBoxes > 0 && usage.UploadedBoxes+1 > policy.DailyBoxes {
+		return http.StatusTooManyRequests, "daily box limit reached"
+	}
+	activeBoxes, err := a.uploadService.ActiveBoxCountForUser(user.ID)
+	if err != nil {
+		return http.StatusInternalServerError, "active box limit could not be checked"
+	}
+	if policy.ActiveBoxes > 0 && activeBoxes+1 > policy.ActiveBoxes {
+		return http.StatusTooManyRequests, "active box limit reached"
+	}
+	return 0, ""
+}
+
 func (a *App) recordUploadUsage(r *http.Request, user services.User, loggedIn bool, totalBytes int64, boxes int) error {
 	now := time.Now().UTC()
 	if loggedIn {