Fix reference image handling for lighting

- Reference image is always sent as second image to model (not limited
  to smart free mode), original image stays as first image
- Prompt explicitly tells model: first image is source, second is
  lighting reference to analyze and apply
- Preview always shows original image, reference image no longer
  replaces it in the globe preview
- Show uploaded reference image thumbnail with clear button in UI
- Add rim light prompt with specific position description and color

src/components/lighting/LightingEffectModal.tsx

@@ -1007,7 +1007,8 @@ export function LightingEffectModal({
   }, [isOpen, value]);
 
   const modalWidthClass = settings.smartMode ? "max-w-[760px]" : "max-w-[458px]";
-  const appliedPreviewImage = settings.referenceImage || sourceImage;
+  // 预览始终显示原始图片（sourceImage）作为打光主体，参考图不替代原图
+  const appliedPreviewImage = sourceImage;
 
   const selectedPreset = useMemo(
     () => LIGHTING_PRESETS.find((preset) => preset.id === settings.selectedPresetId),
@@ -1221,9 +1222,35 @@ export function LightingEffectModal({
                 <button
                   type="button"
                   onClick={() => referenceInputRef.current?.click()}
-                  className="rounded-lg border border-dashed border-neutral-700 bg-neutral-900 px-2 text-xs text-neutral-400 transition-colors hover:border-neutral-500 hover:text-neutral-100"
+                  className="relative h-20 w-20 shrink-0 overflow-hidden rounded-lg border border-dashed border-neutral-700 bg-neutral-900 text-xs text-neutral-400 transition-colors hover:border-neutral-500 hover:text-neutral-100"
                 >
-                  +<br />打光参考图
+                  {settings.referenceImage ? (
+                    <>
+                      {/* eslint-disable-next-line @next/next/no-img-element */}
+                      <img src={settings.referenceImage} alt="打光参考图" className="h-full w-full object-cover" />
+                      <div
+                        role="button"
+                        tabIndex={0}
+                        className="absolute right-0.5 top-0.5 flex h-4 w-4 items-center justify-center rounded-full bg-black/60 text-[10px] leading-none text-white hover:bg-red-600"
+                        onClick={(e) => {
+                          e.stopPropagation();
+                          patchSettings({ referenceImage: null });
+                        }}
+                        onKeyDown={(e) => {
+                          if (e.key === "Enter") {
+                            e.stopPropagation();
+                            patchSettings({ referenceImage: null });
+                          }
+                        }}
+                      >
+                        ×
+                      </div>
+                    </>
+                  ) : (
+                    <span className="flex h-full items-center justify-center text-center leading-tight">
+                      +<br />参考图
+                    </span>
+                  )}
                 </button>
               </div>
               <input

src/store/execution/nanoBananaExecutor.ts

@@ -106,8 +106,9 @@ export async function executeNanoBanana(
   const activeLighting = nodeData.lighting?.enabled ? nodeData.lighting : upstreamLighting;
   const lightingPrompt = images.length > 0 ? buildLightingPrompt(activeLighting) : "";
 
-  // 智能自由模式：将打光参考图追加到图片数组，作为第二张图传给模型
-  if (isSmartFreeMode(activeLighting) && activeLighting.referenceImage) {
+  // 打光参考图：将参考图追加到图片数组，作为第二张图传给模型
+  // 原始图片始终为第一张，参考图为第二张，模型根据参考图的打光风格对原图重打光
+  if (activeLighting?.enabled && activeLighting.referenceImage) {
     images = [...images, activeLighting.referenceImage];
   }
 

src/utils/__tests__/lighting.test.ts

@@ -113,7 +113,7 @@ describe("lighting utilities", () => {
       referenceImage: "data:image/png;base64,abc",
     });
 
-    expect(prompt).toContain("second image is provided");
-    expect(prompt).toContain("lighting reference");
+    expect(prompt).toContain("SECOND image is the lighting reference");
+    expect(prompt).toContain("FIRST image");
   });
 });

src/utils/lighting.ts

@@ -282,8 +282,11 @@ export function buildLightingPrompt(settings?: LightingSettings | null): string
     beamAngleInstruction(lighting.beamAngle),
   ];
 
+  // 轮廓光：在主光源之外追加第二个光源，位于主体后方
+  // 颜色与主光源一致，位置由用户在球体背面拖拽决定
   if (lighting.rimLight) {
     const rimPos = lighting.rimLightPosition ?? DEFAULT_LIGHTING_SETTINGS.rimLightPosition;
+    // 根据 3D 坐标判断轮廓光的水平/垂直/深度方位，生成可读描述
     const rimHoriz = rimPos.x <= -0.25 ? "camera-left" : rimPos.x >= 0.25 ? "camera-right" : "centered";
     const rimVert = rimPos.y <= -0.25 ? "above" : rimPos.y >= 0.25 ? "below" : "at subject level";
     const rimDepth = rimPos.z <= -0.25 ? "directly behind" : rimPos.z >= 0.25 ? "in front of" : "beside";
@@ -319,7 +322,8 @@ export function buildOptimizedLightingPrompt(
 ): string {
   const lightingPrompt = buildLightingPrompt(settings);
   const userPrompt = (basePrompt ?? "").trim();
-  const smartRef = isSmartFreeMode(settings);
+  const lighting = normalizeLightingSettings(settings);
+  const hasRefImage = !!lighting.referenceImage;
 
   // 打光未启用 → 原样返回用户提示词
   if (!lightingPrompt) {
@@ -332,7 +336,7 @@ export function buildOptimizedLightingPrompt(
 
   // 严格约束：锁定人物身份、构图、场景，只允许改变光照
   const constraints = [
-    "STRICT image-to-image relighting task: use the uploaded image as the locked source image.",
+    "STRICT image-to-image relighting task: the FIRST image is the source image to be relit — do not modify its content.",
     userIntent,
     lightingPrompt,
     "The output must show the same exact person from the source image: identical face identity, facial features, age, expression, hair, body shape, hands, pose, clothing, accessories, and camera/phone.",
@@ -342,10 +346,10 @@ export function buildOptimizedLightingPrompt(
     "Do not add or remove people or objects, do not beautify or re-age the person, do not replace the face, do not change hairstyle or clothing, do not crop the subject, and do not create a different scene.",
   ];
 
-  // 智能参考图模式：告知模型第二张图片是打光参考
-  if (smartRef) {
+  // 打光参考图：第二张图片是打光参考，分析其光照风格应用到原图
+  if (hasRefImage) {
     constraints.push(
-      "If a second image is provided, use it as the lighting reference — match its lighting style, direction, color temperature, and mood."
+      "The SECOND image is the lighting reference — analyze its lighting style, direction, color temperature, shadows, and mood, then apply the same lighting to the FIRST image."
     );
   }