diff --git a/app/api/canvas/local-edit/route.ts b/app/api/canvas/local-edit/route.ts
index a4e0d1b2c..a4a357d9d 100644
--- a/app/api/canvas/local-edit/route.ts
+++ b/app/api/canvas/local-edit/route.ts
@@ -398,35 +398,13 @@ function scaleRectAroundCenter(
 
 function getScaleAdjustTargetRect(
   region: NormalizedLocalEditRegion,
-  scalePercent: ScaleAdjustPercent
+  scalePercent?: ScaleAdjustPercent | null
 ) {
-  return region.targetRect || scaleRectAroundCenter(region.rect, scalePercent);
-}
-
-function deriveScaleAdjustPercentFromTargetRect(
-  sourceRect: NormalizedLocalEditRegion["rect"],
-  targetRect: NormalizedLocalEditRegion["rect"] | null | undefined
-) {
-  if (!targetRect || sourceRect.width <= 0 || sourceRect.height <= 0) {
-    return null;
+  if (region.targetRect) return region.targetRect;
+  if (typeof scalePercent === "number" && Number.isFinite(scalePercent)) {
+    return scaleRectAroundCenter(region.rect, scalePercent);
   }
-  const widthRatio = Math.max(0.05, targetRect.width / sourceRect.width);
-  const heightRatio = Math.max(0.05, targetRect.height / sourceRect.height);
-  const uniformRatio = Math.sqrt(widthRatio * heightRatio);
-  const percent = Math.round((uniformRatio - 1) * 100);
-  if (!Number.isFinite(percent) || percent === 0) return null;
-  return clamp(percent, MIN_SCALE_ADJUST_PERCENT, MAX_SCALE_ADJUST_PERCENT);
-}
-
-function deriveScaleAdjustPercentFromRegions(regions: NormalizedLocalEditRegion[]) {
-  for (const region of regions) {
-    const percent = deriveScaleAdjustPercentFromTargetRect(
-      region.rect,
-      region.targetRect
-    );
-    if (percent !== null) return percent;
-  }
-  return null;
+  return region.rect;
 }
 
 function expandRectWithMargins(
@@ -450,11 +428,31 @@ function expandRectWithMargins(
 function getScaleAdjustWorkspaceRect(
   sourceRect: NormalizedLocalEditRegion["rect"],
   targetRect: NormalizedLocalEditRegion["rect"],
-  scalePercent: ScaleAdjustPercent
+  scalePercent?: ScaleAdjustPercent | null
 ) {
-  if (scalePercent <= 0) return targetRect;
+  const sourceWidth = Math.max(0.0001, sourceRect.width);
+  const sourceHeight = Math.max(0.0001, sourceRect.height);
+  const widthGrowthRatio = Math.max(0, targetRect.width / sourceWidth - 1);
+  const heightGrowthRatio = Math.max(0, targetRect.height / sourceHeight - 1);
+  const areaGrowthRatio = Math.max(
+    0,
+    Math.sqrt(
+      Math.max(0.0001, targetRect.width * targetRect.height) /
+        Math.max(0.0001, sourceWidth * sourceHeight)
+    ) - 1
+  );
+  const explicitGrowthRatio = Math.max(
+    widthGrowthRatio,
+    heightGrowthRatio,
+    areaGrowthRatio
+  );
+  const fallbackScaleRatio =
+    typeof scalePercent === "number" && Number.isFinite(scalePercent)
+      ? Math.min(1, Math.max(0, scalePercent / 100))
+      : 0;
+  const scaleRatio = Math.max(explicitGrowthRatio, fallbackScaleRatio);
+  if (scaleRatio <= 0) return targetRect;
 
-  const scaleRatio = Math.min(1, Math.max(0, scalePercent / 100));
   const marginX = Math.min(
     0.12,
     Math.max(0.018, sourceRect.width * scaleRatio * 0.22)
@@ -469,7 +467,7 @@ function getScaleAdjustWorkspaceRect(
 
 function buildScaleAdjustCompositeRegions(
   regions: NormalizedLocalEditRegion[],
-  scalePercent: ScaleAdjustPercent
+  scalePercent?: ScaleAdjustPercent | null
 ) {
   return regions.flatMap((region) => {
     const targetRect = getScaleAdjustTargetRect(region, scalePercent);
@@ -478,7 +476,8 @@ function buildScaleAdjustCompositeRegions(
       targetRect,
       scalePercent
     );
-    return scalePercent > 0
+    return workspaceRect.width > targetRect.width ||
+      workspaceRect.height > targetRect.height
       ? [region.rect, targetRect, workspaceRect]
       : [region.rect, targetRect];
   });
@@ -691,7 +690,7 @@ function buildScaleAdjustAnnotationSvg(params: {
   width: number;
   height: number;
   regions: NormalizedLocalEditRegion[];
-  scalePercent: ScaleAdjustPercent;
+  scalePercent?: ScaleAdjustPercent | null;
 }) {
   const { width, height, regions, scalePercent } = params;
   const minSide = Math.max(1, Math.min(width, height));
@@ -782,7 +781,7 @@ function buildLocalEditPrompt(regions: NormalizedLocalEditRegion[]) {
 
 function buildScaleAdjustPrompt(
   regions: NormalizedLocalEditRegion[],
-  scalePercent: ScaleAdjustPercent,
+  scalePercent: ScaleAdjustPercent | null | undefined,
   cropReferences: ScaleAdjustCropReference[] = [],
   sourceSize?: { width: number; height: number }
 ) {
@@ -925,21 +924,27 @@ export async function POST(request: NextRequest) {
         { status: 400 }
       );
     }
-    if (operation === SCALE_ADJUST_OPERATION && scalePercent === null) {
-      scalePercent = deriveScaleAdjustPercentFromRegions(regions);
-      if (scalePercent === null) {
-        return NextResponse.json(
-          {
-            success: false,
-            error: "请提供比例调整幅度，或为每个区域提供有效的目标框 targetRect",
-          },
-          { status: 400 }
-        );
-      }
+    const hasScaleAdjustTargetRects =
+      operation === SCALE_ADJUST_OPERATION &&
+      regions.length > 0 &&
+      regions.every((region) => Boolean(region.targetRect));
+    if (
+      operation === SCALE_ADJUST_OPERATION &&
+      !hasScaleAdjustTargetRects &&
+      scalePercent === null
+    ) {
+      return NextResponse.json(
+        {
+          success: false,
+          error: "请为每个区域提供有效的目标框 targetRect，或提供比例调整幅度 scalePercent",
+        },
+        { status: 400 }
+      );
     }
 
     const shouldUseScaleAdjustDetailModel =
-      operation === SCALE_ADJUST_OPERATION && scalePercent !== null;
+      operation === SCALE_ADJUST_OPERATION &&
+      (hasScaleAdjustTargetRects || scalePercent !== null);
     const [pointsConfig, siteSettingsForModel, scaleAdjustModelCandidates] =
       await Promise.all([
       getPointsSystemConfig(),
@@ -968,14 +973,15 @@ export async function POST(request: NextRequest) {
     }
 
     const isScaleAdjustOperation =
-      operation === SCALE_ADJUST_OPERATION && scalePercent !== null;
+      operation === SCALE_ADJUST_OPERATION &&
+      (hasScaleAdjustTargetRects || scalePercent !== null);
     const displayPrompt = buildLocalEditDisplayPrompt({ operation, scalePercent });
 
     const annotationSvg = isScaleAdjustOperation
       ? buildScaleAdjustAnnotationSvg({
           height: sourceHeight,
           regions,
-          scalePercent: scalePercent as ScaleAdjustPercent,
+          scalePercent,
           width: sourceWidth,
         })
       : buildAnnotationSvg({
@@ -1015,7 +1021,7 @@ export async function POST(request: NextRequest) {
       isScaleAdjustOperation
         ? buildScaleAdjustPrompt(
             regions,
-            scalePercent as ScaleAdjustPercent,
+            scalePercent,
             scaleAdjustCropReferences,
             { width: sourceWidth, height: sourceHeight }
           )
@@ -1067,10 +1073,7 @@ export async function POST(request: NextRequest) {
     }
     const resolvedModel = detailFixedModel || requestedModel;
     const scaleAdjustCompositeRegions = isScaleAdjustOperation
-      ? buildScaleAdjustCompositeRegions(
-          regions,
-          scalePercent as ScaleAdjustPercent
-        )
+      ? buildScaleAdjustCompositeRegions(regions, scalePercent)
       : [];
 
     const imageRequest: CanvasGenerateImageRequest = {
@@ -1100,6 +1103,9 @@ export async function POST(request: NextRequest) {
         regionCount: regions.length,
         scalePercent,
         scaleAdjustCropReferenceCount: scaleAdjustCropReferenceImageUrls.length,
+        scaleAdjustProtectionMode: hasScaleAdjustTargetRects
+          ? "target-rect"
+          : "scale-percent",
         scaleAdjustTargetRegionCount: regions.filter((region) => region.targetRect)
           .length,
         scaleAdjustPromptStrategy: isScaleAdjustOperation
@@ -1129,7 +1135,21 @@ export async function POST(request: NextRequest) {
             protectedRegions: scaleAdjustCompositeRegions,
             sourceImageUrl,
             regions: regions.map((region) => region.rect),
-            scalePercent: scalePercent as ScaleAdjustPercent,
+            ...(typeof scalePercent === "number"
+              ? { scalePercent: scalePercent as ScaleAdjustPercent }
+              : {}),
+            ...(hasScaleAdjustTargetRects
+              ? {
+                  targetRegions: regions
+                    .map((region) => region.targetRect)
+                    .filter(
+                      (
+                        rect
+                      ): rect is NonNullable<NormalizedLocalEditRegion["targetRect"]> =>
+                        Boolean(rect)
+                    ),
+                }
+              : {}),
           }
         : undefined,
       localEditComposite: isScaleAdjustOperation
diff --git a/lib/canvas/generate-image.ts b/lib/canvas/generate-image.ts
index b13baa40f..7e955e764 100644
--- a/lib/canvas/generate-image.ts
+++ b/lib/canvas/generate-image.ts
@@ -54,7 +54,8 @@ export interface CanvasScaleAdjustVerificationConfig {
   protectedRegions?: CanvasLocalEditCompositeRegion[];
   sourceImageUrl: string;
   regions: CanvasLocalEditCompositeRegion[];
-  scalePercent: number;
+  targetRegions?: CanvasLocalEditCompositeRegion[];
+  scalePercent?: number;
 }
 
 export interface CanvasGenerateImageRequest {
@@ -331,13 +332,23 @@ function normalizeScaleAdjustVerificationConfig(
   if (!value || typeof value !== "object") return null;
   const sourceImageUrl = String(value.sourceImageUrl || "").trim();
   if (!/^https?:\/\//i.test(sourceImageUrl)) return null;
-  const scalePercent = Number(value.scalePercent);
-  if (!Number.isFinite(scalePercent) || Math.abs(scalePercent) < 1) return null;
   if (!Array.isArray(value.regions) || value.regions.length === 0) return null;
+  const rawScalePercent = Number(value.scalePercent);
+  const scalePercent =
+    Number.isFinite(rawScalePercent) && Math.abs(rawScalePercent) >= 1
+      ? rawScalePercent
+      : undefined;
 
   const regions = value.regions
     .map((region) => normalizeCanvasRegion(region))
     .filter((region): region is CanvasLocalEditCompositeRegion => Boolean(region));
+  const targetRegions = Array.isArray((value as { targetRegions?: unknown[] }).targetRegions)
+    ? (value as { targetRegions?: unknown[] }).targetRegions
+        ?.map((region) => normalizeCanvasRegion(region))
+        .filter((region): region is CanvasLocalEditCompositeRegion =>
+          Boolean(region)
+        ) || []
+    : [];
   const protectedRegions = Array.isArray(value.protectedRegions)
     ? value.protectedRegions
         .map((region) => normalizeCanvasRegion(region))
@@ -346,11 +357,13 @@ function normalizeScaleAdjustVerificationConfig(
         )
     : [];
 
-  return regions.length > 0
+  return regions.length > 0 &&
+    (targetRegions.length > 0 || typeof scalePercent === "number")
     ? {
         sourceImageUrl,
         regions,
-        scalePercent,
+        ...(targetRegions.length > 0 ? { targetRegions } : {}),
+        ...(typeof scalePercent === "number" ? { scalePercent } : {}),
         ...(protectedRegions.length > 0 ? { protectedRegions } : {}),
       }
     : null;
@@ -425,13 +438,32 @@ function getScaleAdjustProtectedRegions(
       expandCanvasRegion(region, SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN)
     );
   }
-  return verification.regions.flatMap((region) => [
-    expandCanvasRegion(region, SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN),
-    expandCanvasRegion(
-      scaleRegionAroundCenter(region, verification.scalePercent),
-      SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN
-    ),
-  ]);
+  if (verification.targetRegions?.length) {
+    return verification.regions.flatMap((region, index) => {
+      const targetRegion = verification.targetRegions?.[index];
+      return targetRegion
+        ? [
+            expandCanvasRegion(region, SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN),
+            expandCanvasRegion(
+              targetRegion,
+              SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN
+            ),
+          ]
+        : [expandCanvasRegion(region, SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN)];
+    });
+  }
+  if (typeof verification.scalePercent === "number") {
+    return verification.regions.flatMap((region) => [
+      expandCanvasRegion(region, SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN),
+      expandCanvasRegion(
+        scaleRegionAroundCenter(region, verification.scalePercent as number),
+        SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN
+      ),
+    ]);
+  }
+  return verification.regions.map((region) =>
+    expandCanvasRegion(region, SCALE_ADJUST_OUTSIDE_PROTECTED_MARGIN)
+  );
 }
 
 function getScaleAdjustOutsideSampleRegions(
@@ -756,7 +788,8 @@ async function applyScaleAdjustVerificationToImages(params: {
       debugLabel,
       imageCount: images.length,
       regionCount: verification.regions.length,
-      scalePercent: verification.scalePercent,
+      scalePercent: verification.scalePercent ?? null,
+      targetRegionCount: verification.targetRegions?.length || 0,
     });
     return images;
   }
@@ -810,7 +843,8 @@ async function applyScaleAdjustVerificationToImages(params: {
       protectedRegionCount: verification.protectedRegions?.length || 0,
       regionCount: verification.regions.length,
       regionDiffScores: diffScores.map((score) => Number(score.toFixed(2))),
-      scalePercent: verification.scalePercent,
+      scalePercent: verification.scalePercent ?? null,
+      targetRegionCount: verification.targetRegions?.length || 0,
     });
 
     if (outsideChanged) {