diff --git a/src/components/image-editor/ImageCanvasBackgroundMusicPresetMarquee.tsx b/src/components/image-editor/ImageCanvasBackgroundMusicPresetMarquee.tsx
index ff4af6791..750b46669 100644
--- a/src/components/image-editor/ImageCanvasBackgroundMusicPresetMarquee.tsx
+++ b/src/components/image-editor/ImageCanvasBackgroundMusicPresetMarquee.tsx
@@ -1,6 +1,12 @@
-import { ChevronLeft, ChevronRight } from 'lucide-react';
+import {
+  ChevronDown,
+  ChevronLeft,
+  ChevronRight,
+  ChevronUp,
+} from 'lucide-react';
 import {
   type PointerEvent as ReactPointerEvent,
+  type ReactNode,
   useCallback,
   useEffect,
   useId,
@@ -77,10 +83,13 @@ export function ImageCanvasBackgroundMusicPresetMarquee({
   presets,
   isLocked,
   onSelectPreset,
+  headerTrailing,
 }: {
   presets: readonly BackgroundMusicPromptPreset[];
   isLocked: boolean;
   onSelectPreset: (preset: BackgroundMusicPromptPreset) => void;
+  /** 标题行右端的展示位。字数计数要和「预设」同排，但它属于 composer 的状态。 */
+  headerTrailing?: ReactNode;
 }) {
   const trackId = useId();
   const [isExpanded, setIsExpanded] = useState(false);
@@ -325,13 +334,20 @@ export function ImageCanvasBackgroundMusicPresetMarquee({
           size="xs"
           shape="pill"
           className="image-canvas-editor__background-music-presets-toggle"
+          // 图标化后文案不再进入可访问名，必须由 aria-label 承担。
+          aria-label={isExpanded ? '收起' : '展开'}
           aria-expanded={isExpanded}
           aria-controls={trackId}
           disabled={isLocked}
           onClick={() => setIsExpanded((expanded) => !expanded)}
         >
-          {isExpanded ? '收起' : '展开'}
+          {isExpanded ? (
+            <ChevronUp aria-hidden="true" />
+          ) : (
+            <ChevronDown aria-hidden="true" />
+          )}
         </PlatformActionButton>
+        {headerTrailing}
       </div>
       {isExpanded ? (
         <div
diff --git a/src/components/image-editor/ImageCanvasGenerationComposerView.test.tsx b/src/components/image-editor/ImageCanvasGenerationComposerView.test.tsx
index f503c1c64..5619ee875 100644
--- a/src/components/image-editor/ImageCanvasGenerationComposerView.test.tsx
+++ b/src/components/image-editor/ImageCanvasGenerationComposerView.test.tsx
@@ -999,12 +999,25 @@ describe('ImageCanvasGenerationComposerView', () => {
       '.image-canvas-editor__generation-composer-footer',
     );
     expect(footer).toBeTruthy();
+    // 助手动作与模型、生成同处底部一行：左侧动作，右侧「Suno + 生成」。
     expect(footer?.children[0]?.className).toContain(
-      'image-canvas-editor__option-popover-anchor--model',
+      'image-canvas-editor__background-music-prompt-actions',
     );
     expect(footer?.children[1]?.className).toContain(
+      'image-canvas-editor__option-popover-anchor--model',
+    );
+    expect(footer?.children[2]?.className).toContain(
       'image-canvas-editor__generation-submit',
     );
+    // 字数计数和「预设」同排，收起预设时也必须还在。
+    const presetsHeader = panel.querySelector(
+      '.image-canvas-editor__background-music-presets-header',
+    );
+    expect(
+      presetsHeader?.querySelector(
+        '.image-canvas-editor__background-music-prompt-count',
+      )?.textContent,
+    ).toBe('0 / 200');
     const backgroundMusicModelButton = within(panel).getByRole('button', {
       name: '背景音乐模型 Suno',
     });
diff --git a/src/components/image-editor/ImageCanvasGenerationComposerView.tsx b/src/components/image-editor/ImageCanvasGenerationComposerView.tsx
index b13979dcd..2e900e3ac 100644
--- a/src/components/image-editor/ImageCanvasGenerationComposerView.tsx
+++ b/src/components/image-editor/ImageCanvasGenerationComposerView.tsx
@@ -1,4 +1,14 @@
-import { Check, ChevronDown, Cpu, Film, ImageIcon, Music } from 'lucide-react';
+import {
+  Check,
+  ChevronDown,
+  Cpu,
+  Film,
+  ImageIcon,
+  Music,
+  Sparkles,
+  Undo2,
+  WandSparkles,
+} from 'lucide-react';
 import {
   type CSSProperties,
   type Dispatch,
@@ -19,7 +29,6 @@ import {
 } from '../common/PlatformFloatingMenu';
 import { PlatformInlineOptionButton } from '../common/PlatformInlineOptionButton';
 import { PlatformStatusMessage } from '../common/PlatformStatusMessage';
-import { PlatformTextField } from '../common/PlatformTextField';
 import { ImageCanvasBackgroundMusicPresetMarquee } from './ImageCanvasBackgroundMusicPresetMarquee';
 import {
   appendBackgroundMusicPromptPreset,
@@ -908,84 +917,33 @@ function ImageCanvasAudioGenerationComposerView({
           onSubmit(backgroundMusicDialog);
         }}
       >
-        <PlatformTextField
-          variant="textarea"
+        {/* 与生图 / 生视频 / 角色 / 图标同源：自动增高到 max-h-32 后内部滚动。 */}
+        <AutoGrowTextArea
           aria-label="gpt_description_prompt"
           aria-describedby={promptCounterId}
           aria-invalid={isPromptOverLimit || undefined}
           value={backgroundMusicDialog.prompt}
           readOnly={isLocked}
           placeholder="你希望生成什么音乐？"
-          size="sm"
-          density="compact"
           className="image-canvas-editor__generation-prompt"
           onChange={(event) => updateBackgroundMusicPrompt(event.target.value)}
         />
-        <div className="image-canvas-editor__background-music-prompt-actions">
-          <span
-            id={promptCounterId}
-            className={
-              isPromptOverLimit
-                ? 'image-canvas-editor__background-music-prompt-count image-canvas-editor__background-music-prompt-count--over-limit'
-                : 'image-canvas-editor__background-music-prompt-count'
-            }
-          >
-            {`${promptCodePointCount} / ${BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS}`}
-          </span>
-          <PlatformActionButton
-            type="button"
-            tone="secondary"
-            size="xs"
-            shape="pill"
-            className="image-canvas-editor__background-music-prompt-action"
-            aria-label="AI 补全"
-            disabled={!canComplete}
-            onClick={() => {
-              void backgroundMusicPromptAssist.completePrompt(
-                backgroundMusicDialog.id,
-              );
-            }}
-          >
-            {assistState.status === 'completing' ? '补全中' : 'AI 补全'}
-          </PlatformActionButton>
-          <PlatformActionButton
-            type="button"
-            tone="secondary"
-            size="xs"
-            shape="pill"
-            className="image-canvas-editor__background-music-prompt-action"
-            aria-label="一键简化"
-            disabled={!canSimplify}
-            onClick={() => {
-              void backgroundMusicPromptAssist.simplifyPrompt(
-                backgroundMusicDialog.id,
-              );
-            }}
-          >
-            {assistState.status === 'simplifying' ? '简化中' : '一键简化'}
-          </PlatformActionButton>
-          {isUndoVisible ? (
-            <PlatformActionButton
-              type="button"
-              tone="secondary"
-              size="xs"
-              shape="pill"
-              className="image-canvas-editor__background-music-prompt-action"
-              disabled={!canUndo}
-              onClick={() => {
-                backgroundMusicPromptAssist.undoPrompt(
-                  backgroundMusicDialog.id,
-                );
-              }}
-            >
-              撤销
-            </PlatformActionButton>
-          ) : null}
-        </div>
         <ImageCanvasBackgroundMusicPresetMarquee
           presets={BACKGROUND_MUSIC_PROMPT_PRESETS}
           isLocked={isLocked}
           onSelectPreset={handlePresetClick}
+          headerTrailing={
+            <span
+              id={promptCounterId}
+              className={
+                isPromptOverLimit
+                  ? 'image-canvas-editor__background-music-prompt-count image-canvas-editor__background-music-prompt-count--over-limit'
+                  : 'image-canvas-editor__background-music-prompt-count'
+              }
+            >
+              {`${promptCodePointCount} / ${BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS}`}
+            </span>
+          }
         />
         {assistState.errorMessage ? (
           <PlatformStatusMessage
@@ -1010,6 +968,79 @@ function ImageCanvasAudioGenerationComposerView({
           </PlatformStatusMessage>
         ) : null}
         <div className="image-canvas-editor__generation-composer-footer">
+          <div className="image-canvas-editor__background-music-prompt-actions">
+            <PlatformActionButton
+              type="button"
+              tone="secondary"
+              size="xs"
+              shape="pill"
+              className="image-canvas-editor__background-music-prompt-action image-canvas-editor__background-music-prompt-action--complete"
+              aria-label="AI 补全"
+              disabled={!canComplete}
+              onClick={() => {
+                void backgroundMusicPromptAssist.completePrompt(
+                  backgroundMusicDialog.id,
+                );
+              }}
+            >
+              <span
+                className="image-canvas-editor__background-music-prompt-action-icon"
+                aria-hidden="true"
+              >
+                <Sparkles />
+              </span>
+              <span>
+                {assistState.status === 'completing' ? '补全中' : 'AI 补全'}
+              </span>
+            </PlatformActionButton>
+            <PlatformActionButton
+              type="button"
+              tone="secondary"
+              size="xs"
+              shape="pill"
+              className="image-canvas-editor__background-music-prompt-action image-canvas-editor__background-music-prompt-action--simplify"
+              aria-label="一键简化"
+              disabled={!canSimplify}
+              onClick={() => {
+                void backgroundMusicPromptAssist.simplifyPrompt(
+                  backgroundMusicDialog.id,
+                );
+              }}
+            >
+              <span
+                className="image-canvas-editor__background-music-prompt-action-icon"
+                aria-hidden="true"
+              >
+                <WandSparkles />
+              </span>
+              <span>
+                {assistState.status === 'simplifying' ? '简化中' : '一键简化'}
+              </span>
+            </PlatformActionButton>
+            {isUndoVisible ? (
+              <PlatformActionButton
+                type="button"
+                tone="ghost"
+                size="xs"
+                shape="pill"
+                className="image-canvas-editor__background-music-prompt-action image-canvas-editor__background-music-prompt-action--undo"
+                disabled={!canUndo}
+                onClick={() => {
+                  backgroundMusicPromptAssist.undoPrompt(
+                    backgroundMusicDialog.id,
+                  );
+                }}
+              >
+                <span
+                  className="image-canvas-editor__background-music-prompt-action-icon"
+                  aria-hidden="true"
+                >
+                  <Undo2 />
+                </span>
+                <span>撤销</span>
+              </PlatformActionButton>
+            ) : null}
+          </div>
           <div className="image-canvas-editor__option-popover-anchor image-canvas-editor__option-popover-anchor--model image-canvas-editor__readonly-generation-option">
             <PlatformInlineOptionButton
               className="image-canvas-editor__option-cluster image-canvas-editor__option-cluster--model"
diff --git a/src/index.css b/src/index.css
index c7cc03cf9..08b67f89f 100644
--- a/src/index.css
+++ b/src/index.css
@@ -16800,20 +16800,110 @@ button {
 /* BGM composer：Prompt 计数、助手动作与预设轨道。 */
 .image-canvas-editor__generation-composer--background-music {
   grid-template-columns: minmax(0, 1fr);
-  grid-template-rows: auto auto auto auto;
   width: min(44rem, calc(100% - 1.5rem));
+  /*
+   * 行数交给 `--image` 的 `auto auto auto` 与隐式行：多写的显式行即使高度为 0，行间距
+   * 仍然照算，收起预设时会凭空多出一段空白。同理 `min-height` 归零，否则 grid 默认的
+   * align-content: stretch 会把撑出来的余量摊到各行上。
+   */
+  min-height: 0;
+}
+
+/* 助手动作与「Suno + 生成」同处底部一行，共享 footer 的 5 列 grid 在这里换成 flex。 */
+.image-canvas-editor__generation-composer--background-music
+  .image-canvas-editor__generation-composer-footer {
+  display: flex;
+  align-items: center;
+  gap: 0.4rem;
+  padding-top: 0.5rem;
+}
+
+/* flex 布局下提交按钮硬编码的 grid-column 自动失效，无需为 BGM 覆盖它。 */
+.image-canvas-editor__generation-composer--background-music
+  .image-canvas-editor__option-popover-anchor--model {
+  margin-left: auto;
+}
+
+.image-canvas-editor__generation-composer--background-music
+  .image-canvas-editor__generation-submit {
+  height: 2.25rem;
+  min-height: 0;
 }
 
 .image-canvas-editor__background-music-prompt-actions {
-  grid-column: 1 / -1;
   display: flex;
   align-items: center;
   gap: 0.4rem;
   min-width: 0;
 }
 
+/*
+ * 助手动作按钮：`.platform-button` 给的是 2.9rem 高与 0.7rem/1rem 内边距，比同一面板里
+ * 2.25rem 的生成按钮高出一截。这里按两级选择器压回去，避免整排按钮比主操作还重。
+ */
+.image-canvas-editor__background-music-prompt-actions
+  .image-canvas-editor__background-music-prompt-action {
+  /* 2.25rem 是本 composer 的控件高度基准（模型 chip 与生成按钮同源）。 */
+  height: 2.25rem;
+  min-height: 0;
+  gap: 0.3rem;
+  /* `shape="pill"` 走的是 Tailwind 分层 utility，压不过未分层的 `.platform-button`
+   * 的 1rem 圆角，所以胶囊圆角必须在这里显式写死。 */
+  border: 1px solid rgba(15, 23, 42, 0.12);
+  border-radius: 999px;
+  background: transparent;
+  padding: 0 0.82rem;
+  color: #475569;
+  font-size: 0.78rem;
+  font-weight: 760;
+  box-shadow: none;
+}
+
+.image-canvas-editor__background-music-prompt-action-icon {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.image-canvas-editor__background-music-prompt-action-icon svg {
+  width: 0.85rem;
+  height: 0.85rem;
+}
+
+/* AI 补全是这一排的主操作，用品牌描边与中性的简化、撤销拉开层级。 */
+.image-canvas-editor__background-music-prompt-actions
+  .image-canvas-editor__background-music-prompt-action--complete {
+  border-color: var(--image-canvas-brand-border-strong);
+  color: var(--image-canvas-brand-accent);
+}
+
+.image-canvas-editor__background-music-prompt-action--complete:not(
+    :disabled
+  ):hover {
+  background: var(--image-canvas-brand-soft);
+}
+
+.image-canvas-editor__background-music-prompt-action--simplify:not(
+    :disabled
+  ):hover {
+  background: rgba(15, 23, 42, 0.04);
+}
+
+/* 撤销权重最低：无边框无底色，只在 hover 时给一层淡底。 */
+.image-canvas-editor__background-music-prompt-actions
+  .image-canvas-editor__background-music-prompt-action--undo {
+  border-color: transparent;
+  color: #64748b;
+}
+
+.image-canvas-editor__background-music-prompt-action--undo:not(
+    :disabled
+  ):hover {
+  background: rgba(15, 23, 42, 0.05);
+}
+
 .image-canvas-editor__background-music-prompt-count {
-  margin-right: auto;
+  margin-left: auto;
   color: #64748b;
   font-size: 0.72rem;
   font-weight: 700;
@@ -16843,6 +16933,32 @@ button {
   font-weight: 800;
 }
 
+/*
+ * 展开 / 收起只是「预设」标题旁的一个箭头，不该是实心 pill。命中区靠 1.75rem 方形保住，
+ * 不做成裸图标那种小到点不中的按钮。
+ */
+.image-canvas-editor__background-music-presets-toggle {
+  width: 1.75rem;
+  height: 1.75rem;
+  min-height: 0;
+  border: 0;
+  border-radius: 999px;
+  background: transparent;
+  padding: 0;
+  color: #64748b;
+  box-shadow: none;
+}
+
+.image-canvas-editor__background-music-presets-toggle:not(:disabled):hover {
+  background: rgba(15, 23, 42, 0.05);
+  color: #334155;
+}
+
+.image-canvas-editor__background-music-presets-toggle svg {
+  width: 0.9rem;
+  height: 0.9rem;
+}
+
 .image-canvas-editor__background-music-presets-track {
   position: relative;
   display: grid;
@@ -16853,15 +16969,25 @@ button {
   padding-bottom: 0.28rem;
 }
 
+/* 轨道两侧的箭头是辅助控件：默认贴边无框，hover 才浮出淡底。宽度保持 1.5rem，
+ * 细线两端的 1.74rem 缩进（箭头 1.5rem + 轨道 0.24rem 间距）因此不用跟着改。 */
 .image-canvas-editor__background-music-presets-arrow {
   display: inline-flex;
   align-items: center;
   justify-content: center;
   width: 1.5rem;
   height: 1.5rem;
-  border: 1px solid rgba(15, 23, 42, 0.08);
+  border: 0;
   border-radius: 999px;
-  background: #f8fafc;
+  background: transparent;
+  color: #94a3b8;
+  transition:
+    background-color 160ms ease,
+    color 160ms ease;
+}
+
+.image-canvas-editor__background-music-presets-arrow:not(:disabled):hover {
+  background: rgba(15, 23, 42, 0.05);
   color: #475569;
 }
 
@@ -16983,6 +17109,12 @@ button {
     flex-wrap: wrap;
   }
 
+  /* 一行放不下三个助手按钮加 Suno 和生成，窄屏必须允许换行。 */
+  .image-canvas-editor__generation-composer--background-music
+    .image-canvas-editor__generation-composer-footer {
+    flex-wrap: wrap;
+  }
+
   .image-canvas-editor__background-music-preset {
     max-width: 9rem;
   }