fix(canvas): 画布 - 防止旧内容覆盖并支持版本历史恢复

web/src/services/canvas-sync-drafts.ts

@@ -0,0 +1,40 @@
+import { nanoid } from "nanoid";
+import { localForageStorageForScope } from "@/lib/localforage-storage";
+import { getActiveUserScope } from "@/lib/user-scope";
+import { sameCanvasContent } from "@/lib/canvas/canvas-content";
+import { withCanvasStorePersistenceLock, type CanvasProject } from "@/stores/canvas/use-canvas-store";
+import { withGenerationArtifactCommitLock } from "@/services/generation-asset-repository";
+
+export type CanvasSyncDraft = { id: string; savedAt: string; project: CanvasProject };
+const draftKey = (projectId: string) => `infinite-canvas:sync-drafts:${projectId}`;
+const draftIndexKey = "infinite-canvas:sync-draft-index";
+
+export async function readAllCanvasSyncDrafts(scope = getActiveUserScope()) {
+    const raw = await localForageStorageForScope(scope).getItem(draftIndexKey);
+    const ids: string[] = raw ? JSON.parse(raw) : [];
+    return (await Promise.all(ids.map((id) => readCanvasSyncDrafts(id, scope)))).flat();
+}
+
+export async function readCanvasSyncDrafts(projectId: string, scope = getActiveUserScope()): Promise<CanvasSyncDraft[]> {
+    const raw = await localForageStorageForScope(scope).getItem(draftKey(projectId));
+    return raw ? JSON.parse(raw) : [];
+}
+
+export async function preserveCanvasSyncDraft(project: CanvasProject, scope = getActiveUserScope()) {
+    // A separate record survives replacement of the active canvas and a browser reload.
+    const snapshot = structuredClone(project);
+    return withGenerationArtifactCommitLock(scope, () =>
+        withCanvasStorePersistenceLock(scope, async () => {
+            const drafts = await readCanvasSyncDrafts(snapshot.id, scope);
+            if (!drafts.some((draft) => sameCanvasContent(draft.project, snapshot))) {
+                const storage = localForageStorageForScope(scope);
+                const rawIndex = await storage.getItem(draftIndexKey);
+                const ids: string[] = rawIndex ? JSON.parse(rawIndex) : [];
+                if (!ids.includes(snapshot.id)) await storage.setItem(draftIndexKey, JSON.stringify([...ids, snapshot.id]));
+                drafts.push({ id: nanoid(), savedAt: new Date().toISOString(), project: snapshot });
+                await storage.setItem(draftKey(snapshot.id), JSON.stringify(drafts));
+            }
+            return drafts.length;
+        }),
+    );
+}