fix(tui): Tighten message and tool spacing

.qwen/design/tui-spacing-density-pr1.md

@@ -0,0 +1,79 @@
+# TUI Spacing And Density PR1
+
+## Why
+
+The current TUI often spends extra rows on spacing before assistant output,
+between status/tool blocks, and inside expanded tool groups. In common
+sessions this makes simple answers, file lists, tool output, error states,
+diffs, and long streaming output harder to scan because users need to scroll
+through blank space rather than content.
+
+This PR is the first focused pass for QwenLM/qwen-code#4588. It addresses only
+spacing and density so the review can compare row usage before and after
+without also reviewing thinking visibility, tool borders, SubAgent layout,
+branding, or theme color changes.
+
+## How
+
+The implementation keeps the existing information structure and rendering
+surfaces intact:
+
+- History item spacing is centralized near `HistoryItemDisplay`. User prompts
+  and standalone command views still start with a turn separator, while
+  assistant continuations, tool groups, status messages, tool summaries, and
+  related in-turn output no longer add an extra leading spacer row.
+- Expanded tool groups keep their current border and status/title structure,
+  but no longer insert blank rows between adjacent tool entries.
+- Tool results render directly below the tool title/status row. This removes
+  the extra blank line between the tool header and its output without changing
+  output content, truncation, shell focus, confirmation prompts, or compact
+  mode behavior.
+
+Markdown blank-line behavior is intentionally left unchanged. The renderer
+already collapses consecutive blank lines to one spacer and preserves complex
+blocks such as tables, code blocks, and math blocks.
+
+## Spacing Standard
+
+- Independent user turns keep one visual separator.
+- Assistant output and in-turn follow-up blocks do not add a second separator.
+- Tool header and tool result content are adjacent.
+- Expanded multi-tool groups do not insert blank rows between each tool entry.
+- Complex Markdown blocks keep their existing internal layout.
+
+## Expected Effect
+
+Under the same terminal width and same rendered content, target scenarios should
+use fewer visible rows:
+
+- Simple Q&A should drop at least one visible row.
+- Expanded tool output should drop at least one row for each rendered tool
+  result that previously had a blank header/result spacer.
+- Multi-tool groups should drop one row between each adjacent tool entry.
+- Project inspection, diff, file-list, error, and long-stream scenarios should
+  not gain rows unless terminal wrapping changes make that unavoidable.
+
+## Measurement
+
+The automated spacing assertions and terminal evidence use 100-column fixtures
+for the changed rules:
+
+| Scenario | Width | Baseline rows | PR1 rows | Delta | Evidence |
+| --- | ---: | ---: | ---: | ---: | --- |
+| Simple assistant reply | 100 | 2 | 1 | -1 | leading history spacer removed |
+| Tool header with one-line result | 100 | 3 | 2 | -1 | header and result are adjacent |
+| Three-tool expanded group with rendered results | 100 | 16 | 11 | -5 | one header/result spacer removed per tool result and one inter-tool separator removed between adjacent tools |
+| Full representative fixture | 100 | 26 | 19 | -7 | same rendered content captured in tmux |
+
+The snapshot diffs also cover the existing 80-column fixtures to confirm the
+same row-count deltas in the current component test harness.
+
+## Out Of Scope
+
+- Hiding thinking traces.
+- Removing tool borders.
+- Redesigning SubAgent output.
+- Changing startup branding or the banner.
+- Changing theme colors.
+- Adding per-turn assistant elapsed time.
+- Changing table inline-code highlighting.

.qwen/design/tui-user-message-half-line-pr2.md

@@ -0,0 +1,76 @@
+# TUI 间距优化 PR2 — 半行色带与紧凑间距
+
+## 背景
+
+PR1 通过去除工具组内部多余空行，初步收紧了 TUI 垂直间距。但在实际使用中仍有两个体验问题：
+
+1. **用户消息与助手回复之间缺少视觉分界** — 长对话中难以快速定位"我的提问从哪里开始"
+2. **块间距仍然偏大** — 输入区域上方、问答交替处各有一整行空白，浪费屏幕空间
+
+## 本次改动
+
+### 1. 用户消息半行色带
+
+在用户消息上下各添加一条半高的淡色线条，形成类似"色带"的视觉效果：
+
+```
+▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄   ← 淡色半行线（仅占半个字符高度）
+> 用户的提问内容
+▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀   ← 淡色半行线
+```
+
+- 颜色自动适配深色/浅色主题，在背景色基础上混入 15% 主题强调色，不会过于显眼
+- 不支持 24 位色的终端自动降级为普通显示
+
+### 2. 收紧问答间距
+
+| 位置 | 改动前 | 改动后 |
+|------|--------|--------|
+| 用户消息上方 | 1 行空白 | 0（由色带提供视觉分隔） |
+| 助手回复与工具之间 | 1 行空白 | 0 |
+| 工具与下一段回复之间 | 1 行空白 | 0 |
+
+同一轮对话内的"回复 → 工具调用 → 回复"序列不再有多余空行，信息更紧凑连贯。
+
+### 3. 输入区域分隔线
+
+底部输入框上方的 1 行空白替换为一条半高淡色分隔线，视觉更轻，占用空间减半。
+
+## 效果对比
+
+**改动前：**
+```
+（1 行空白）
+> 帮我读取 package.json
+（1 行空白）
+✦ 好的，我来读取文件。
+（1 行空白）
+┌ Read package.json ─────────┐
+│ ✓ Read  package.json       │
+└────────────────────────────┘
+（1 行空白）
+✦ 文件内容如下：...
+
+（1 行空白）
+┌─ 输入框 ──────────────────┐
+```
+
+**改动后：**
+```
+▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
+> 帮我读取 package.json
+▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
+✦ 好的，我来读取文件。
+┌ Read package.json ─────────┐
+│ ✓ Read  package.json       │
+└────────────────────────────┘
+✦ 文件内容如下：...
+▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
+┌─ 输入框 ──────────────────┐
+```
+
+## 未改动
+
+- 工具调用边框样式保持不变
+- Markdown 正文段落间距保持不变（1 行已是终端最小单位）
+- 深色/浅色主题色值不变

.qwen/e2e-tests/tui-spacing-density-pr1.md

@@ -0,0 +1,92 @@
+# TUI Spacing And Density PR1 Evidence
+
+## Goal
+
+Provide before/after evidence that PR1 reduces visible row usage without
+removing content or changing rendering scope.
+
+## Fixed Conditions
+
+- Terminal width: 100 columns.
+- Compare the same prompt/output fixture before and after this PR.
+- Strip ANSI control sequences before counting visible rows.
+- Count rendered rows from the first non-empty fixture row through the last
+  non-empty fixture row. This keeps internal blank spacer rows in the metric
+  because those are the rows this PR removes.
+- The fixture renders the real Ink TUI components directly, so it does not
+  require a model call or network access.
+
+## Scenarios
+
+- Simple Q&A.
+- File list output.
+- Long shell output.
+- File-read error output.
+- Multi-block project inspection output.
+- Diff output.
+- Long streaming output.
+
+## Commands
+
+Terminal capture:
+
+```bash
+git checkout origin/main
+REPO_ROOT="$PWD"
+/tmp/qwen-pr1-spacing-evidence/run-tmux-capture.sh "$REPO_ROOT" 'base origin/main 34b7d472e' base
+git switch feat/tui-spacing-density-pr1
+/tmp/qwen-pr1-spacing-evidence/run-tmux-capture.sh "$REPO_ROOT" 'PR1 fixed 848d6a166' fixed
+```
+
+VHS visual capture:
+
+```bash
+git checkout origin/main
+PATH=/Users/gawain/.nvm/versions/node/v24.15.0/bin:$PATH vhs /tmp/qwen-pr1-spacing-evidence/base.tape
+git switch feat/tui-spacing-density-pr1
+PATH=/Users/gawain/.nvm/versions/node/v24.15.0/bin:$PATH vhs /tmp/qwen-pr1-spacing-evidence/fixed.tape
+ffmpeg -y -i /tmp/qwen-pr1-spacing-evidence/base.gif -i /tmp/qwen-pr1-spacing-evidence/fixed.gif -filter_complex "[0:v]fps=5,scale=780:-1:flags=lanczos[left];[1:v]fps=5,scale=780:-1:flags=lanczos[right];[left][right]hstack=inputs=2,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" /tmp/qwen-pr1-spacing-evidence/base-vs-fixed-optimized.gif
+```
+
+## Evidence Artifacts
+
+- Release: <https://github.com/QwenLM/qwen-code/releases/tag/tui-spacing-density-pr1-evidence>
+- Side-by-side GIF: <https://github.com/QwenLM/qwen-code/releases/download/tui-spacing-density-pr1-evidence/base-vs-fixed-optimized.gif>
+- Final screenshot: <https://github.com/QwenLM/qwen-code/releases/download/tui-spacing-density-pr1-evidence/base-vs-fixed-final.png>
+- Base tmux capture: <https://github.com/QwenLM/qwen-code/releases/download/tui-spacing-density-pr1-evidence/base.tmux.txt>
+- Fixed tmux capture: <https://github.com/QwenLM/qwen-code/releases/download/tui-spacing-density-pr1-evidence/fixed.tmux.txt>
+- Base summary JSON: <https://github.com/QwenLM/qwen-code/releases/download/tui-spacing-density-pr1-evidence/base.summary.json>
+- Fixed summary JSON: <https://github.com/QwenLM/qwen-code/releases/download/tui-spacing-density-pr1-evidence/fixed.summary.json>
+
+## Expected Results
+
+- Simple Q&A: at least 1 fewer visible row.
+- Expanded tool output: at least 1 fewer visible row per rendered tool result
+  that previously had a blank header/result spacer.
+- Multi-tool expanded groups: 1 fewer visible row between each adjacent tool
+  entry.
+- No scenario should lose user-visible content.
+
+## Results
+
+| Scenario | Width | Baseline rows | PR1 rows | Delta | Notes |
+| --- | ---: | ---: | ---: | ---: | --- |
+| Simple Q&A | 100 | 2 | 1 | -1 | Assistant history item no longer starts with a spacer row |
+| File list or shell output | 100 | 3 | 2 | -1 | Tool header and first result row are adjacent |
+| File-read error | 100 | 3 | 2 | -1 | Error result uses the same tool header/result spacing |
+| Project inspection | 100 | 16 | 11 | -5 | Three expanded tools no longer have header/result spacer rows or blank inter-tool rows |
+| Diff output | 100 | 3 | 2 | -1 | Diff renderer remains unchanged; only tool header/result spacing changes |
+| Long streaming output | 100 | N + 2 | N + 1 | -1 | Content rows are unchanged; the extra header/result spacer is removed |
+| Full representative fixture | 100 | 26 | 19 | -7 | Same content rendered through real Ink components and captured in tmux |
+
+## What This Proves
+
+- The base branch reproduces the extra spacer rows in a real terminal capture.
+- PR1 removes the targeted spacer rows while preserving the same fixture content.
+- The row-count improvement is measurable under fixed 100-column conditions.
+
+## What This Does Not Prove
+
+- It does not cover later PR scopes such as thinking trace visibility, tool
+  border removal, SubAgent layout, branding, or theme colors.
+- It does not replace manual review for extremely narrow terminal wrapping.

packages/cli/src/ui/components/Composer.tsx

@@ -16,6 +16,11 @@ import { useUIActions } from '../contexts/UIActionsContext.js';
 import { useVimMode } from '../contexts/VimModeContext.js';
 import { useConfig } from '../contexts/ConfigContext.js';
 import { theme } from '../semantic-colors.js';
+import {
+  interpolateColor,
+  resolveColor,
+  supportsTrueColor,
+} from '../themes/color-utils.js';
 import { StreamingState, type HistoryItemToolGroup } from '../types.js';
 import { FeedbackDialog } from '../FeedbackDialog.js';
 import { t } from '../../i18n/index.js';
@@ -91,8 +96,22 @@ export const Composer = () => {
     [uiActions],
   );
 
+  const composerWidth = uiState.terminalWidth - 4;
+  const separatorColor = supportsTrueColor()
+    ? interpolateColor(
+        resolveColor(theme.background.primary || 'black') || 'black',
+        resolveColor(theme.text.secondary) || theme.text.secondary,
+        0.15,
+      )
+    : undefined;
+
   return (
-    <Box flexDirection="column" marginTop={1}>
+    <Box flexDirection="column" marginTop={separatorColor ? 0 : 1}>
+      {separatorColor && (
+        <Text color={separatorColor}>
+          {'▄'.repeat(Math.max(0, composerWidth))}
+        </Text>
+      )}
       {!uiState.embeddedShellFocused && !suppressBottomLoadingIndicator && (
         <LoadingIndicator
           // Hide loading phrases when enableLoadingPhrases is explicitly false.

packages/cli/src/ui/components/HistoryItemDisplay.test.tsx

@@ -58,6 +58,37 @@ describe('<HistoryItemDisplay />', () => {
     expect(lastFrame()).toContain('/theme');
   });
 
+  it('renders assistant replies without a leading spacer row', () => {
+    const item: HistoryItem = {
+      id: 1,
+      type: 'gemini',
+      text: 'Hello',
+    };
+    const { lastFrame } = renderWithProviders(
+      <HistoryItemDisplay item={item} terminalWidth={100} isPending={false} />,
+    );
+
+    const output = lastFrame() ?? '';
+    expect(output.startsWith('\n')).toBe(false);
+    expect(output).toContain('✦ Hello');
+  });
+
+  it('renders tool summaries without a leading spacer row', () => {
+    const item: HistoryItem = {
+      id: 1,
+      type: 'tool_use_summary',
+      summary: 'Read txt files',
+      precedingToolUseIds: ['c1'],
+    };
+    const { lastFrame } = renderWithProviders(
+      <HistoryItemDisplay item={item} terminalWidth={100} isPending={false} />,
+    );
+
+    const output = lastFrame() ?? '';
+    expect(output.startsWith('\n')).toBe(false);
+    expect(output).toContain('Read txt files');
+  });
+
   it('renders StatsDisplay for "stats" type', () => {
     const item: HistoryItem = {
       ...baseItem,

packages/cli/src/ui/components/HistoryItemDisplay.tsx

@@ -87,6 +87,37 @@ interface HistoryItemDisplayProps {
   sourceCopyIndexOffsets?: MarkdownSourceCopyIndexOffsets;
 }
 
+function getHistoryItemMarginTop(item: HistoryItem): number {
+  switch (item.type) {
+    case 'gemini':
+    case 'gemini_content':
+    case 'gemini_thought':
+    case 'gemini_thought_content':
+    case 'info':
+    case 'success':
+    case 'warning':
+    case 'error':
+    case 'retry_countdown':
+    case 'memory_saved':
+    case 'tool_group':
+    case 'tool_use_summary':
+    case 'notification':
+    case 'compression':
+    case 'summary':
+    case 'insight_progress':
+    case 'btw':
+    case 'away_recap':
+    case 'user':
+    case 'user_prompt_submit_blocked':
+    case 'stop_hook_loop':
+    case 'stop_hook_system_message':
+    case 'goal_status':
+      return 0;
+    default:
+      return 1;
+  }
+}
+
 const HistoryItemDisplayComponent: React.FC<HistoryItemDisplayProps> = ({
   item,
   availableTerminalHeight,
@@ -102,10 +133,7 @@ const HistoryItemDisplayComponent: React.FC<HistoryItemDisplayProps> = ({
   summaryAbsorbed = false,
   sourceCopyIndexOffsets,
 }) => {
-  const marginTop =
-    item.type === 'gemini_content' || item.type === 'gemini_thought_content'
-      ? 0
-      : 1;
+  const marginTop = getHistoryItemMarginTop(item);
 
   const { compactMode } = useCompactMode();
   const itemForDisplay = useMemo(() => escapeAnsiCtrlCodes(item), [item]);
@@ -122,7 +150,7 @@ const HistoryItemDisplayComponent: React.FC<HistoryItemDisplayProps> = ({
     >
       {/* Render standard message types */}
       {itemForDisplay.type === 'user' && (
-        <UserMessage text={itemForDisplay.text} />
+        <UserMessage text={itemForDisplay.text} width={contentWidth} />
       )}
       {itemForDisplay.type === 'notification' && (
         <InfoMessage text={itemForDisplay.text} />