improve flow

website/src/lib/engine/engine.ts

@@ -33,9 +33,6 @@ import {
     type WaypointDetails,
 } from './types';
 
-/** The error of the outcomes while the stored files come from a newer version of the app. */
-const OUTDATED = 'saved by a newer version';
-
 /**
  * Thin wrapper around the WASM engine.
  *
@@ -70,7 +67,7 @@ class Engine {
     readonly order: Readable<string[]> = { subscribe: this._order.subscribe };
     /** Statistics of what is currently selected. */
     readonly statistics: Readable<SelectionStatistics> = this._statistics.store;
-    /** Whether the stored files are from a newer version of the app: they cannot be changed. */
+    /** Whether the stored files are from a newer version of the app: changes are not kept, the page has to be reloaded. */
     readonly outdated: Readable<boolean> = { subscribe: this._outdated.subscribe };
     readonly canUndo: Readable<boolean> = { subscribe: this._canUndo.subscribe };
     readonly canRedo: Readable<boolean> = { subscribe: this._canRedo.subscribe };
@@ -116,6 +113,7 @@ class Engine {
                 wasm: this.wasm!,
                 visibility: this._visibility,
                 sync: (update) => this.sync(this.wasm!, update),
+                outdated: () => this._outdated.set(true),
                 hasFiles: () => get(this._order).length > 0,
                 loadFiles: (files) => this.loadFiles(files),
                 deselect: () => this.select([]),
@@ -702,16 +700,13 @@ class Engine {
         this._lastError.set(outcome.error);
         if (outcome.error === 'nothing to do') {
             console.debug('engine:', outcome.error);
-        } else if (outcome.error !== undefined && outcome.error !== OUTDATED) {
+        } else if (outcome.error !== undefined) {
             console.warn('engine:', outcome.error);
         }
     }
 
     /** Updates what is kept of the engine with what a call changed. */
     private sync(wasm: Wasm, update: Outcome) {
-        if (update.error === OUTDATED) {
-            this._outdated.set(true);
-        }
         this._canUndo.set(wasm.can_undo());
         this._canRedo.set(wasm.can_redo());
         this._canPaste.set(wasm.can_paste());

website/src/lib/engine/storage.ts

@@ -16,6 +16,8 @@ export type StorageHost = {
     visibility: Map<string, Visibility>;
     /** Applies what a call changed to what the facade keeps of the files. */
     sync(update: Outcome): void;
+    /** Tells that what is stored comes from a newer version of the app: nothing can be saved. */
+    outdated(): void;
     hasFiles(): boolean;
     loadFiles(files: { data: Uint8Array; name: string }[]): Promise<boolean>;
     deselect(): Promise<boolean>;
@@ -27,7 +29,11 @@ export type StorageHost = {
  * what they hold (see `sync_storage`). The same happens when a write of this tab is refused
  * because of that, and when the tab is shown again (a hidden tab can miss messages).
  */
-function followOtherTabs(host: StorageHost): { saved: () => void; behind: () => void } {
+function followOtherTabs(host: StorageHost): {
+    saved: () => void;
+    behind: () => void;
+    newer: () => void;
+} {
     const { wasm } = host;
     let reading = Promise.resolve();
     const refresh = () => {
@@ -47,7 +53,11 @@ function followOtherTabs(host: StorageHost): { saved: () => void; behind: () =>
             }
         });
     }
-    return { saved: () => channel?.postMessage('saved'), behind: refresh };
+    return {
+        saved: () => channel?.postMessage('saved'),
+        behind: refresh,
+        newer: () => host.outdated(),
+    };
 }
 
 /**
@@ -61,7 +71,7 @@ export async function openStoredFiles(host: StorageHost): Promise<Record<string,
     let opened: StorageOpened;
     const tabs = followOtherTabs(host);
     try {
-        opened = await wasm.open_storage(STORAGE_NAME, tabs.saved, tabs.behind);
+        opened = await wasm.open_storage(STORAGE_NAME, tabs.saved, tabs.behind, tabs.newer);
     } catch (error) {
         console.error('The files cannot be kept in this browser', error);
         return {};