feat(canvas): 条件读取与历史 - 减少画布同步传输并校准版本

web/src/lib/canvas/canvas-content.ts

@@ -12,11 +12,30 @@ export function sameCanvasContent(left: CanvasProject | undefined, right: Canvas
     if (!left || !right) return false;
     const a = canvasContentSnapshot(left) as Record<string, unknown>;
     const b = canvasContentSnapshot(right) as Record<string, unknown>;
-    return [...new Set([...Object.keys(a), ...Object.keys(b)])].every((key) => a[key] === b[key] || canonicalize(a[key]) === canonicalize(b[key]));
+    return [...new Set([...Object.keys(a), ...Object.keys(b)])].every((key) => {
+        if (a[key] === b[key]) return true;
+        if ((key === "nodes" || key === "connections") && Array.isArray(a[key]) && Array.isArray(b[key])) {
+            const leftItems = a[key] as unknown[];
+            const rightItems = b[key] as unknown[];
+            return leftItems.length === rightItems.length && leftItems.every((item, index) => item === rightItems[index] || canonicalValue(item) === canonicalValue(rightItems[index]));
+        }
+        return canonicalValue(a[key]) === canonicalValue(b[key]);
+    });
 }
 
 type ContentSnapshot = ReturnType<typeof canvasContentSnapshot>;
 const contentHashes = new WeakMap<CanvasProject["nodes"], { content: ContentSnapshot; hash: Promise<string> }>();
+// Canvas content trees are immutable, so unchanged node objects can reuse their serialized comparison value.
+const canonicalValueCache = new WeakMap<object, string>();
+
+function canonicalValue(value: unknown) {
+    if (!value || typeof value !== "object") return canonicalize(value);
+    const cached = canonicalValueCache.get(value);
+    if (cached) return cached;
+    const serialized = canonicalize(value);
+    canonicalValueCache.set(value, serialized);
+    return serialized;
+}
 
 // Store updates are immutable. Reuse a hash across viewport/revision-only copies;
 // any content field/reference change invalidates it. Weak keys bound its lifetime.