fix(canvas): independently verify product support structure before accepting replacements

lib/canvas/layout-replace-product-support.ts

@@ -0,0 +1,27 @@
+export const LAYOUT_REPLACE_SUPPORT_PROMPT = [
+  "只观察这张图中主体商品本身的下缘与支撑方式，不比较其他图片，不根据商品类别或广告文案猜测。",
+  "supportType只能选：flush=连续底座直接贴地；legs=可见独立柜腿、支撑脚或脚轮使柜体离地；suspended=明确悬挂；not_applicable=该类别不适用支撑结构检查（如服装、食品）；unclear=无法看清。",
+  "贴地底座的接触阴影不是腿。只有实际看到独立支撑才选legs，不要凭空想象隐藏的脚。关注实际商品，忽略海报图标、数字及其他独立摆件。",
+  '只返回JSON，supportType填写上述英文枚举之一：{"supportType":"从枚举中选择","confidence":0.95}。',
+].join("\n");
+
+export type LayoutReplaceSupport = "flush" | "legs" | "suspended" | "not_applicable" | "unclear";
+
+export function parseLayoutReplaceSupport(text: string) {
+  let value: { supportType?: unknown; confidence?: unknown };
+  try { value = JSON.parse(text.trim().replace(/^```(?:json)?\s*/i, "").replace(/\s*```$/, "")); }
+  catch { throw new Error("商品支撑结构检查未返回有效结论"); }
+  if (!value || !["flush", "legs", "suspended", "not_applicable", "unclear"].includes(String(value.supportType)) ||
+    typeof value.confidence !== "number" || value.confidence < 0 || value.confidence > 1) throw new Error("商品支撑结构检查不完整");
+  return { supportType: value.supportType as LayoutReplaceSupport, confidence: value.confidence };
+}
+
+export function compareLayoutReplaceSupport(source: ReturnType<typeof parseLayoutReplaceSupport>, result: ReturnType<typeof parseLayoutReplaceSupport>) {
+  if (source.supportType === "not_applicable") return { passed: true, reason: "" };
+  if (source.supportType === "unclear" || result.supportType === "unclear" || source.confidence < .8 || result.confidence < .8) {
+    return { passed: false, reason: "无法可靠确认商品下缘的支撑结构" };
+  }
+  const names = { flush: "贴地底座", legs: "独立腿脚或脚轮", suspended: "悬挂", not_applicable: "类别不适用", unclear: "不清晰" };
+  return source.supportType === result.supportType ? { passed: true, reason: "" }
+    : { passed: false, reason: `原商品为${names[source.supportType]}，结果却为${names[result.supportType]}，支撑结构已改变` };
+}

lib/canvas/layout-replace-verifier.ts

@@ -10,6 +10,7 @@ import { LAYOUT_REPLACE_PRODUCT_PROMPT, parseLayoutReplaceProductAnalysis } from
 import { LAYOUT_REPLACE_TEXT_PROMPT, parseLayoutReplaceTextBoxes, LAYOUT_REPLACE_TEXT_CHECK_PROMPT, parseLayoutReplaceTextCheck } from "./layout-replace-text-lock";
 import type { NormalizedReplacementBox } from "@/lib/ai/replacement-layout-lock";
 import { makeLayoutReplaceQualityBoard } from "./layout-replace-quality-board";
+import { LAYOUT_REPLACE_SUPPORT_PROMPT, parseLayoutReplaceSupport, compareLayoutReplaceSupport } from "./layout-replace-product-support";
 
 async function visionInput(buffer: Buffer) {
   const resized = await sharp(buffer, { failOn: "error" }).rotate()
@@ -86,6 +87,22 @@ export async function locateLayoutReplaceTemplateText(buffer: Buffer) {
   return result;
 }
 
+const supportChecks = new Map<string, { expires: number; result: ReturnType<typeof inspectProductSupport> }>();
+function inspectProductSupport(buffer: Buffer) {
+  return inspectLayoutImages([buffer], LAYOUT_REPLACE_SUPPORT_PROMPT, parseLayoutReplaceSupport);
+}
+export async function inspectLayoutReplaceSupport(buffer: Buffer) {
+  const key = createHash("sha256").update(buffer).digest("hex");
+  const cached = supportChecks.get(key);
+  if (cached && cached.expires > Date.now()) return cached.result;
+  if (supportChecks.size >= 64) supportChecks.delete(supportChecks.keys().next().value!);
+  const result = inspectProductSupport(buffer);
+  const entry = { expires: Date.now() + 30 * 60_000, result };
+  supportChecks.set(key, entry);
+  result.catch(() => { if (supportChecks.get(key) === entry) supportChecks.delete(key); });
+  return result;
+}
+
 export async function verifyCanvasLayoutReplacement(params: {
   sourceBuffer: Buffer;
   templateBuffer: Buffer;
@@ -101,6 +118,15 @@ export async function verifyCanvasLayoutReplacement(params: {
   const board = await makeLayoutReplaceQualityBoard({ template: params.templateBuffer, source: params.sourceBuffer,
     product: params.productBuffer || params.sourceBuffer, result: resultBuffer });
   const quality = await inspectLayoutImages([board], prompt, parseLayoutReplaceQuality);
+  if (quality.sourceProductPreserved) {
+    const [sourceSupport, resultSupport] = await Promise.all([
+      inspectLayoutReplaceSupport(params.productBuffer || params.sourceBuffer), inspectLayoutReplaceSupport(resultBuffer),
+    ]);
+    const support = compareLayoutReplaceSupport(sourceSupport, resultSupport);
+    if (!support.passed) return { ...quality, passed: false, sourceProductPreserved: false,
+      confidence: Math.min(quality.confidence, sourceSupport.confidence, resultSupport.confidence),
+      reasons: [...quality.reasons, support.reason] };
+  }
   if (!quality.passed || !params.textBoundingBoxes?.length) return quality;
   const text = await verifyLayoutReplaceText(params.templateBuffer, resultBuffer, params.textBoundingBoxes);
   return { ...quality, passed: text.passed, templateTextPreserved: text.passed,

tests/integration/layout-replace-validation.test.ts

@@ -6,6 +6,7 @@ import { runValidatedLayoutReplacement } from "@/lib/canvas/layout-replace-valid
 import { buildCanvasLayoutReplacePrompt, rankCanvasLayoutReplaceModels } from "@/lib/canvas/layout-replace-model-selection";
 import { parseLayoutReplaceProductBox, parseLayoutReplaceProductAnalysis, layoutReplaceProductCrop, layoutReplaceProductAspectRatio } from "@/lib/canvas/layout-replace-product-crop";
 import { makeLayoutReplaceQualityBoard } from "@/lib/canvas/layout-replace-quality-board";
+import { parseLayoutReplaceSupport, compareLayoutReplaceSupport } from "@/lib/canvas/layout-replace-product-support";
 import { parseLayoutReplaceTextBoxes, parseLayoutReplaceTextCheck } from "@/lib/canvas/layout-replace-text-lock";
 
 const verdict = { sourceProductPreserved: true, templateLayoutPreserved: true,
@@ -117,6 +118,18 @@ test("structured OCR differences preserve numeric changes and discard unchanged
   assert.equal(equivalent.passed, true);
 });
 
+test("independently observed support types reject added legs without confusing template legs with results", () => {
+  const observed = (supportType: string, confidence = .95) => parseLayoutReplaceSupport(JSON.stringify({ supportType, confidence }));
+  assert.equal(compareLayoutReplaceSupport(observed("flush"), observed("flush")).passed, true);
+  assert.equal(compareLayoutReplaceSupport(observed("flush"), observed("legs")).passed, false);
+  assert.equal(compareLayoutReplaceSupport(observed("legs"), observed("flush")).passed, false);
+  assert.equal(compareLayoutReplaceSupport(observed("suspended"), observed("legs")).passed, false);
+  assert.equal(compareLayoutReplaceSupport(observed("not_applicable"), observed("unclear")).passed, true);
+  assert.equal(compareLayoutReplaceSupport(observed("flush"), observed("unclear")).passed, false);
+  assert.equal(compareLayoutReplaceSupport(observed("flush"), observed("flush", .3)).passed, false);
+  assert.throws(() => parseLayoutReplaceSupport('{"supportType":"maybe","confidence":0.95}'));
+});
+
 test("quality rejection covers identity, background direction, copy loss, collage and low confidence", () => {
   assert.equal(quality().passed, true);
   for (const changes of [{ sourceProductPreserved: false }, { templateLayoutPreserved: false },