fix(自学): 手机上读课好读多了：长代码不再被截掉半行（折行接着缩进），表格不再一字一行，填空的注释不再折成像另一行代码、空也大了；往下读时底栏收起、读到课末不再有两个「下一课」；点下一课落在新课开头而不是末尾；输出预测不再把同一个问题问两遍

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/oj/learn/components/CodeRunBlock.vue

@@ -10,6 +10,8 @@ import { explainRuntimeError } from "oj/problem/utils/runtimeError"
 import { useAuthModalStore } from "shared/store/authModal"
 import { useUserStore } from "shared/store/user"
 import { mainWrapExtensions, wrapMain } from "../wrapMain"
+import { hangWrapExtensions } from "../hangIndent"
+import { useBreakpoints } from "shared/composables/breakpoints"
 
 const CodeEditor = defineAsyncComponent(() => import("shared/components/CodeEditor.vue"))
 
@@ -35,7 +37,12 @@ const message = useMessage()
 const { copy } = useClipboard({ legacy: true })
 
 const original = computed(() => (props.wrapMain ? wrapMain(props.code) : props.code))
-const extensions = computed(() => (props.wrapMain ? mainWrapExtensions : []))
+const { isDesktop } = useBreakpoints()
+// 手机上折行（见 hangIndent.ts）；桌面正文 720 宽，长行少，照旧横着滚
+const extensions = computed(() => [
+  ...(props.wrapMain ? mainWrapExtensions : []),
+  ...(isDesktop.value ? [] : hangWrapExtensions),
+])
 const value = ref(original.value)
 const input = ref("")
 const running = ref(false)

apps/web/src/oj/learn/components/ExerciseDebug.vue

@@ -2,6 +2,7 @@
 import ExerciseResult from "./ExerciseResult.vue"
 import type { Exercise, ExerciseDebugData } from "utils/types"
 import { highlightLines } from "shared/highlight"
+import { hangStyle } from "../hangIndent"
 
 const props = defineProps<{ exercise: Exercise; lang?: string }>()
 const emit = defineEmits<{
@@ -93,7 +94,7 @@ function reset() {
 
     <n-space vertical :size="6">
       <div
-        v-for="(_line, idx) in data.lines"
+        v-for="(line, idx) in data.lines"
         :key="idx"
         :style="lineStyle(idx)"
         @click="toggle(idx)"
@@ -101,7 +102,7 @@ function reset() {
         <span style="color: #bbb; width: 22px; text-align: right; flex-shrink: 0">
           {{ idx + 1 }}
         </span>
-        <span v-html="lineHtml[idx]" style="white-space: pre; min-width: 0; overflow-x: auto" />
+        <span v-html="lineHtml[idx]" :style="{ minWidth: 0, ...hangStyle(line) }" />
       </div>
     </n-space>
 

apps/web/src/oj/learn/components/ExerciseFill.vue

@@ -2,6 +2,7 @@
 import ExerciseResult from "./ExerciseResult.vue"
 import type { Exercise, ExerciseFillData } from "utils/types"
 import { highlightWithHoles } from "shared/highlight"
+import { hangStyle } from "../hangIndent"
 
 const props = defineProps<{ exercise: Exercise; lang?: string }>()
 const emit = defineEmits<{
@@ -37,6 +38,32 @@ const segments = computed<Segment[]>(() => {
   )
 })
 
+/**
+ * 按行切开，每行自己折行、悬挂缩进（见 hangIndent.ts）。原来整段 pre-wrap，
+ * 手机上行尾的注释折下来顶格，看着像另起了一行代码。
+ * 高亮的 HTML 在换行处是断开的（见 shared/highlight.ts 的 walk），按 "\n" 切不会切坏标签。
+ */
+const lines = computed(() => {
+  const rows: { indent: string; parts: Segment[] }[] = [{ indent: "", parts: [] }]
+  for (const seg of segments.value) {
+    if (seg.type === "blank") {
+      rows[rows.length - 1].parts.push(seg)
+      continue
+    }
+    seg.html.split("\n").forEach((html, i) => {
+      if (i > 0) rows.push({ indent: "", parts: [] })
+      if (html) rows[rows.length - 1].parts.push({ type: "code", html })
+    })
+  }
+  for (const row of rows) {
+    const first = row.parts[0]
+    if (first?.type === "code") {
+      row.indent = first.html.replace(/<[^>]*>/g, "").match(/^[ \t]*/)![0]
+    }
+  }
+  return rows
+})
+
 const blankCount = computed(() => segments.value.filter((s) => s.type === "blank").length)
 const userInputs = ref<string[]>([])
 const wrongBlanks = ref<Set<number>>(new Set())
@@ -78,52 +105,59 @@ function inputWidth(idx: number): string {
       {{ data.question }}
     </p>
 
-    <pre
+    <div
       :style="{
         fontFamily: 'var(--learn-code-font)',
         fontSize: '16px',
-        lineHeight: '1.6',
+        lineHeight: '1.9',
         background: 'var(--learn-soft)',
         border: '1px solid var(--learn-line)',
         borderRadius: '6px',
-        padding: '12px',
-        overflowX: 'auto',
-        whiteSpace: 'pre-wrap',
-        margin: 0,
+        padding: '10px 12px',
       }"
-    ><template v-for="(seg, i) in segments" :key="i"
-      ><span v-if="seg.type === 'code'" v-html="seg.html" /><input
-        v-else
-        :value="userInputs[seg.index]"
-        :disabled="allCorrect"
-        autocapitalize="off"
-        autocorrect="off"
-        autocomplete="off"
-        spellcheck="false"
-        :style="{
-          width: inputWidth(seg.index),
-          fontFamily: 'var(--learn-code-font)',
-          fontSize: '16px',
-          padding: '0 6px',
-          borderRadius: '3px',
-          border: `1.5px solid ${
-            allCorrect
-              ? '#18a058'
-              : wrongBlanks.has(seg.index)
-                ? '#d03050'
-                : 'var(--learn-control-line)'
-          }`,
-          background: allCorrect
-            ? 'rgba(24,160,88,0.08)'
-            : wrongBlanks.has(seg.index)
-              ? 'rgba(208,48,80,0.07)'
-              : 'transparent',
-          outline: 'none',
-          color: 'inherit',
-          minWidth: '4ch',
-        }"
-        @input="userInputs[seg.index] = ($event.target as HTMLInputElement).value"
-      /></template></pre>
+    >
+      <div
+        v-for="(row, r) in lines"
+        :key="r"
+        :style="{ minHeight: '1.9em', ...hangStyle(row.indent) }"
+      >
+        <template v-for="(seg, i) in row.parts" :key="i"
+          ><span v-if="seg.type === 'code'" v-html="seg.html" /><input
+            v-else
+            :value="userInputs[seg.index]"
+            :disabled="allCorrect"
+            autocapitalize="off"
+            autocorrect="off"
+            autocomplete="off"
+            spellcheck="false"
+            :style="{
+              width: inputWidth(seg.index),
+              fontFamily: 'var(--learn-code-font)',
+              fontSize: '16px',
+              lineHeight: '1.4',
+              padding: '2px 6px',
+              textIndent: 0,
+              borderRadius: '4px',
+              border: `1.5px solid ${
+                allCorrect
+                  ? '#18a058'
+                  : wrongBlanks.has(seg.index)
+                    ? '#d03050'
+                    : 'var(--learn-control-line)'
+              }`,
+              background: allCorrect
+                ? 'rgba(24,160,88,0.08)'
+                : wrongBlanks.has(seg.index)
+                  ? 'rgba(208,48,80,0.07)'
+                  : 'var(--learn-pane)',
+              outline: 'none',
+              color: 'inherit',
+              minWidth: '5ch',
+            }"
+            @input="userInputs[seg.index] = ($event.target as HTMLInputElement).value"
+        /></template>
+      </div>
+    </div>
 
     <ExerciseResult
       v-if="wrongBlanks.size > 0 || allCorrect"

apps/web/src/oj/learn/components/ExercisePredict.vue

@@ -74,7 +74,11 @@ function reset() {
       }"
     ><code style="font-family: inherit" v-html="codeHtml" /></pre>
 
-    <p style="font-weight: 500; margin: 14px 0 8px">这段代码会输出什么？</p>
+    <!-- 题目本身多半就是这句，再写一遍就成了同一个问题问两次 -->
+    <p v-if="!data.question.includes('输出什么')" style="font-weight: 500; margin: 14px 0 8px">
+      这段代码会输出什么？
+    </p>
+    <div v-else style="height: 14px" />
     <n-input
       v-model:value="userInput"
       type="textarea"

apps/web/src/oj/learn/components/ExerciseSort.vue

@@ -4,6 +4,7 @@ import type { Exercise, ExerciseSortData } from "utils/types"
 import { shuffle } from "../composables/useShuffle"
 import { highlightLines } from "shared/highlight"
 import { useBreakpoints } from "shared/composables/breakpoints"
+import { hangStyle } from "../hangIndent"
 
 const props = defineProps<{ exercise: Exercise; lang?: string }>()
 const emit = defineEmits<{
@@ -140,7 +141,7 @@ const lineHtml = computed<string[]>(() => highlightLines(data.value.lines, props
         <span style="color: #bbb; cursor: grab">⠿</span>
         <span
           v-html="lineHtml[line.originalIdx]"
-          style="white-space: pre; min-width: 0; overflow-x: auto"
+          :style="{ minWidth: 0, ...hangStyle(line.text) }"
         />
       </div>
     </n-space>

apps/web/src/oj/learn/components/LessonBody.vue

@@ -66,6 +66,15 @@ function inline(text: string) {
   margin: 28px 0 12px;
   scroll-margin-top: 16px;
 }
+/* 手机上四列的表会把每格挤成一两个字一行（「浮」「点」「数」）：给格子留个最小宽度、表头不折，
+   放不下就整张横着滚（Markdown.vue 已经让表格自己滚） */
+.body :deep(.oj-markdown th),
+.body :deep(.oj-markdown td) {
+  min-width: 4em;
+}
+.body :deep(.oj-markdown th) {
+  white-space: nowrap;
+}
 .goals {
   margin: 4px 0 8px;
   padding: 12px 16px;

apps/web/src/oj/learn/hangIndent.ts

@@ -0,0 +1,78 @@
+import { RangeSetBuilder } from "@codemirror/state"
+import {
+  Decoration,
+  type DecorationSet,
+  EditorView,
+  ViewPlugin,
+  type ViewUpdate,
+} from "@codemirror/view"
+
+/**
+ * 手机上代码折行。原来是横着滚，可没有滚动条也看不出右边还有，
+ * 综合练习那种长 print 整整半行看不见。折下来的那截缩到这一行的代码下面再进两格，
+ * 一眼看得出还是同一行。
+ */
+
+/** 行首空白占几格，tab 按 4 */
+function leadingWidth(text: string): number {
+  let width = 0
+  for (const ch of text) {
+    if (ch === " ") width++
+    else if (ch === "\t") width += 4
+    else break
+  }
+  return width
+}
+
+/** 静态的代码行（练一练的排序、找错、填空）：折行，接着的那截悬挂缩进 */
+export function hangStyle(text: string): Record<string, string> {
+  const width = leadingWidth(text) + 2
+  return {
+    whiteSpace: "pre-wrap",
+    // 中文连着的一串别从中间断（「类」「型」各在一行），实在放不下才随便断
+    wordBreak: "keep-all",
+    overflowWrap: "anywhere",
+    paddingLeft: `${width}ch`,
+    textIndent: `-${width}ch`,
+  }
+}
+
+function hangDecorations(view: EditorView): DecorationSet {
+  const builder = new RangeSetBuilder<Decoration>()
+  for (const { from, to } of view.visibleRanges) {
+    for (let pos = from; pos <= to;) {
+      const line = view.state.doc.lineAt(pos)
+      const width = leadingWidth(line.text) + 2
+      // 6px 是 CodeMirror 给 .cm-line 的左内边距，盖掉了要补回来
+      builder.add(
+        line.from,
+        line.from,
+        Decoration.line({
+          attributes: {
+            style: `padding-left: calc(${width}ch + 6px); text-indent: -${width}ch; word-break: keep-all; overflow-wrap: anywhere`,
+          },
+        }),
+      )
+      pos = line.to + 1
+    }
+  }
+  return builder.finish()
+}
+
+const hangPlugin = ViewPlugin.fromClass(
+  class {
+    decorations: DecorationSet
+    constructor(view: EditorView) {
+      this.decorations = hangDecorations(view)
+    }
+    update(update: ViewUpdate) {
+      if (update.docChanged || update.viewportChanged) {
+        this.decorations = hangDecorations(update.view)
+      }
+    }
+  },
+  { decorations: (plugin) => plugin.decorations },
+)
+
+/** 编辑器（正文里能运行的代码块）：折行 + 悬挂缩进 */
+export const hangWrapExtensions = [EditorView.lineWrapping, hangPlugin]

apps/web/src/oj/learn/index.vue

@@ -138,7 +138,11 @@ async function init() {
   activeId.value = ""
   await nextTick()
   reader.value?.scrollTo({ top: 0 })
-  if (!isDesktop.value) window.scrollTo({ top: 0 })
+  // 手机上滚的是外层 n-layout 的容器，不是 window —— 原来 window.scrollTo 什么都没滚，
+  // 点「下一课」落在下一课的末尾
+  if (!isDesktop.value) scroller()?.scrollTo({ top: 0 })
+  pagerHidden.value = false
+  atEnd.value = false
 }
 
 watch(
@@ -178,6 +182,51 @@ function onSolved(exerciseId: number) {
   progress.value = { ...progress.value, [id]: { ...row, exerciseSolved: solvedCount.value } }
 }
 
+// ------------------------------------------------------------------ 手机底栏
+// 往下读时收起上一课 / 目录 / 下一课，往回翻再出来；读到课末也收着 ——
+// 课末卡片里就有「下一课」，两个摆在一起是重复的
+const mobileRoot = ref<HTMLElement | null>(null)
+const endRef = ref<HTMLElement | null>(null)
+const pagerHidden = ref(false)
+const atEnd = ref(false)
+
+/** 往上找真正在滚的那层。n-layout-content 自己也带 .n-layout-scroll-container 类却不滚，按类名找会找错 */
+function scroller(): HTMLElement | null {
+  for (let el = mobileRoot.value?.parentElement; el; el = el.parentElement) {
+    const overflow = getComputedStyle(el).overflowY
+    if ((overflow === "auto" || overflow === "scroll") && el.scrollHeight > el.clientHeight) {
+      return el
+    }
+  }
+  return null
+}
+
+let lastTop = 0
+function onMobileScroll(event: Event) {
+  const box = event.target as HTMLElement
+  const top = box.scrollTop
+  if (top < 60) pagerHidden.value = false
+  else if (top > lastTop + 6) pagerHidden.value = true
+  else if (top < lastTop - 6) pagerHidden.value = false
+  lastTop = top
+  const end = endRef.value?.getBoundingClientRect().top
+  atEnd.value = end !== undefined && end < box.getBoundingClientRect().bottom
+}
+
+// 滚动事件不冒泡，在 document 上用捕获拿，不用先找到容器再挂
+useEventListener(
+  document,
+  "scroll",
+  (event: Event) => {
+    const box = event.target
+    if (isDesktop.value || !(box instanceof HTMLElement)) return
+    // 只认包着本页的那层（目录抽屉、代码块里横着滚的不算）
+    if (!mobileRoot.value || !box.contains(mobileRoot.value)) return
+    onMobileScroll(event)
+  },
+  { capture: true, passive: true },
+)
+
 // ------------------------------------------------------------------ 读到哪一节
 const reader = ref<HTMLElement | null>(null)
 const activeId = ref("")
@@ -234,7 +283,9 @@ function jumpExercise(id: number) {
 
       <main class="main">
         <div ref="reader" class="reader" @scroll.passive="onScroll">
-          <article v-if="tutorial" class="article">
+          <!-- 按课重建：复用的话正文里的编辑器是就地换内容，CodeMirror 会把光标滚进视野，
+               刚滚回顶上的页面又被拽到某个代码块那儿 -->
+          <article v-if="tutorial" :key="tutorial.id" class="article">
             <div class="crumb muted">
               <span v-if="tutorial.project">{{ tutorial.project }}</span>
               <span v-if="tutorial.project">·</span>
@@ -302,7 +353,7 @@ function jumpExercise(id: number) {
     </div>
 
     <!-- 手机 -->
-    <div v-else class="mobile">
+    <div v-else ref="mobileRoot" class="mobile">
       <div class="mbar">
         <n-button @click="menuOpen = true">
           <template #icon><Icon icon="ph:list" /></template>
@@ -322,7 +373,7 @@ function jumpExercise(id: number) {
           </span>
         </span>
       </div>
-      <article v-if="tutorial" class="marticle">
+      <article v-if="tutorial" :key="tutorial.id" class="marticle">
         <div v-if="tutorial.project" class="crumb muted">{{ tutorial.project }}</div>
         <h1 class="h1 small">{{ parts.kp }}</h1>
         <div v-if="parts.scene" class="scene">{{ parts.scene }}</div>
@@ -334,24 +385,26 @@ function jumpExercise(id: number) {
           :solved-ids="solvedIds"
           @solved="onSolved"
         />
-        <LessonEnd
-          :step="step"
-          :total="titles.length"
-          :course-label="courseLabel"
-          :exercise-count="parsed.exerciseCount"
-          :solved-count="solvedCount"
-          :first-unsolved="firstUnsolved"
-          :problems="tutorial.problems"
-          :next="next"
-          :groups="groups"
-          :state-of="stateOf"
-          :done-count="done"
-          compact
-          @jump="jumpExercise"
-        />
+        <div ref="endRef">
+          <LessonEnd
+            :step="step"
+            :total="titles.length"
+            :course-label="courseLabel"
+            :exercise-count="parsed.exerciseCount"
+            :solved-count="solvedCount"
+            :first-unsolved="firstUnsolved"
+            :problems="tutorial.problems"
+            :next="next"
+            :groups="groups"
+            :state-of="stateOf"
+            :done-count="done"
+            compact
+            @jump="jumpExercise"
+          />
+        </div>
       </article>
       <n-spin v-else-if="loading" class="spin" />
-      <nav class="mpager">
+      <nav class="mpager" :class="{ hidden: pagerHidden || atEnd }">
         <n-button v-if="prev" size="large" @click="router.push(prev.to)">
           <template #icon><Icon icon="ph:caret-left-bold" /></template>
           上一课
@@ -374,7 +427,14 @@ function jumpExercise(id: number) {
         </n-button>
       </nav>
 
-      <n-drawer v-model:show="menuOpen" placement="bottom" height="85%" class="sheet">
+      <!-- 不自动聚焦：一打开焦点框套在「自学首页」上，手机上看着像出了错 -->
+      <n-drawer
+        v-model:show="menuOpen"
+        placement="bottom"
+        height="85%"
+        class="sheet"
+        :auto-focus="false"
+      >
         <n-drawer-content :native-scrollbar="false" closable>
           <template #header>
             <span class="sheet-head">
@@ -582,6 +642,10 @@ function jumpExercise(id: number) {
   display: flex;
   align-items: center;
   background: v-bind("theme.bodyColor");
+  transition: transform 0.2s ease;
+}
+.mpager.hidden {
+  transform: translateY(100%);
 }
 .sheet-head {
   display: flex;