diff --git a/apps/kimi-web/src/App.vue b/apps/kimi-web/src/App.vue
index d71852bc..8bca4045 100644
--- a/apps/kimi-web/src/App.vue
+++ b/apps/kimi-web/src/App.vue
@@ -38,7 +38,7 @@ import type { SwarmMember } from './composables/swarmGroups';
 import ServerAuthDialog from './components/ServerAuthDialog.vue';
 import { initServerAuth, onAuthRequired } from './api/daemon/serverAuth';
 import type { AppConfig, ThinkingLevel } from './api/types';
-import { commitLevel, effectiveThinkingLevel, segmentsFor } from './lib/modelThinking';
+import { commitLevel, defaultThinkingLevelFor, effectiveThinkingLevel, segmentsFor } from './lib/modelThinking';
 import { stripSkillPrefix } from './lib/slashCommands';
 import Button from './components/ui/Button.vue';
 import IconButton from './components/ui/IconButton.vue';
@@ -119,7 +119,7 @@ function nextThinkingLevel(current: ThinkingLevel | undefined): ThinkingLevel {
   // No stored preference means the model default is in effect — cycle from
   // there; a level the model doesn't declare (indexOf → -1) starts the cycle
   // at the first segment.
-  const idx = segs.indexOf(effectiveThinkingLevel(model, current));
+  const idx = segs.indexOf(effectiveThinkingLevel(model, current ?? defaultThinkingLevelFor(model)));
   const next = segs[(idx + 1) % segs.length] ?? segs[0] ?? 'off';
   return commitLevel(model, next);
 }
@@ -129,7 +129,7 @@ function nextThinkingLevel(current: ThinkingLevel | undefined): ThinkingLevel {
 // will actually run, not a blank.
 const statusPanelThinking = computed<ThinkingLevel>(() => {
   const model = client.models.value.find((m) => m.id === client.status.value.modelId);
-  return effectiveThinkingLevel(model, client.thinking.value);
+  return effectiveThinkingLevel(model, client.thinking.value ?? defaultThinkingLevelFor(model));
 });
 
 // First-run onboarding (language + welcome greeting). Shown until the user
diff --git a/apps/kimi-web/src/api/daemon/client.ts b/apps/kimi-web/src/api/daemon/client.ts
index 5ff57e74..08775c5a 100644
--- a/apps/kimi-web/src/api/daemon/client.ts
+++ b/apps/kimi-web/src/api/daemon/client.ts
@@ -933,6 +933,21 @@ export class DaemonKimiWebApi implements KimiWebApi {
     };
   }
 
+  /** POST /sessions/{id}/fs:mkdir — create a directory. FS_ALREADY_EXISTS (40919)
+   *  is treated as success (the directory is ready to use). */
+  async makeDirectory(
+    sessionId: string,
+    input: { path: string },
+  ): Promise<{ made: boolean; path: string }> {
+    const data = await this.http.post<{ made: boolean; path: string }>(
+      `/sessions/${encodeURIComponent(sessionId)}/fs:mkdir`,
+      { path: input.path },
+      { allowCodes: [40919] }, // FS_ALREADY_EXISTS
+    );
+    return { made: data?.made ?? false, path: input.path };
+  }
+
+
   async readFile(
     sessionId: string,
     input: { path: string; offset?: number; length?: number },
diff --git a/apps/kimi-web/src/api/types.ts b/apps/kimi-web/src/api/types.ts
index cbcde2d0..e16acbd3 100644
--- a/apps/kimi-web/src/api/types.ts
+++ b/apps/kimi-web/src/api/types.ts
@@ -706,6 +706,8 @@ export interface KimiWebApi {
   getTerminal(sessionId: string, terminalId: string): Promise<AppTerminal>;
   closeTerminal(sessionId: string, terminalId: string): Promise<{ closed: true }>;
   listDirectory(sessionId: string, input: { path?: string; depth?: number; includeGitStatus?: boolean }): Promise<{ items: FsEntry[]; childrenByPath?: Record<string, FsEntry[]>; truncated: boolean }>;
+  /** Create a directory. Returns FS_ALREADY_EXISTS (40919) when the path already exists — callers should treat that as success. */
+  makeDirectory(sessionId: string, input: { path: string }): Promise<{ made: boolean; path: string }>;
   readFile(sessionId: string, input: { path: string; offset?: number; length?: number }): Promise<{ path: string; content: string; encoding: 'utf-8' | 'base64'; size: number; truncated: boolean; etag: string; mime: string; languageId?: string; lineCount?: number; isBinary: boolean }>;
   searchFiles(sessionId: string, input: { query: string; limit?: number }): Promise<{ items: Array<{ path: string; name: string; kind: FsKind; score: number; matchPositions: number[] }>; truncated: boolean }>;
   grepFiles(sessionId: string, input: { pattern: string; regex?: boolean; caseSensitive?: boolean }): Promise<{ files: Array<{ path: string; matches: Array<{ line: number; col: number; text: string; before: string[]; after: string[] }> }>; filesScanned: number; truncated: boolean; elapsedMs: number }>;
diff --git a/apps/kimi-web/src/components/chat/Composer.vue b/apps/kimi-web/src/components/chat/Composer.vue
index 111c06fd..f3e33dcd 100644
--- a/apps/kimi-web/src/components/chat/Composer.vue
+++ b/apps/kimi-web/src/components/chat/Composer.vue
@@ -10,6 +10,7 @@ import type { FileItem } from './MentionMenu.vue';
 import type { ActivationBadges, ConversationStatus, PermissionMode, QueuedPromptView } from '../../types';
 import type { AppGoal, AppModel, AppSkill, ThinkingLevel } from '../../api/types';
 import {
+  defaultThinkingLevelFor,
   commitLevel,
   effectiveThinkingLevel,
   effortLabel,
@@ -617,7 +618,7 @@ const thinkingSegments = computed(() => segmentsFor(currentModel.value));
 // the model default, which is what the daemon will resolve for the prompt. A
 // level the model doesn't declare highlights no segment but still shows in the
 // suffix.
-const thinkingLevel = computed(() => effectiveThinkingLevel(currentModel.value, props.thinking));
+const thinkingLevel = computed(() => effectiveThinkingLevel(currentModel.value, props.thinking ?? defaultThinkingLevelFor(currentModel.value)));
 const activeThinkingSegment = computed(() => {
   const segs = thinkingSegments.value;
   return segs.includes(thinkingLevel.value) ? thinkingLevel.value : '';
diff --git a/apps/kimi-web/src/i18n/locales/en/study.ts b/apps/kimi-web/src/i18n/locales/en/study.ts
index 86f739d1..0843e52a 100644
--- a/apps/kimi-web/src/i18n/locales/en/study.ts
+++ b/apps/kimi-web/src/i18n/locales/en/study.ts
@@ -71,21 +71,38 @@ export default {
     outlineDesigning: 'Kimi is designing the outline from your material and goal…',
     outlineCounts: '{chapters} chapters · {pages} pages · {quizzes} quizzes',
     outlineReviseTitle: 'Ask for a change',
-    outlineRevisePlaceholder: 'e.g. “Add a chapter on boundary cases”…',
+    outlineRevisePlaceholder: 'Describe the outline change in one sentence…',
+    outlineReviseExample: 'For example: assume no prior knowledge; lead with examples; reduce to 6 lessons; move risk analysis first.',
     outlineReviseAction: 'Update outline',
     outlineReviseSent: 'Change requested — a new outline revision will appear here once it passes review.',
-    outlineReviseError: 'The outline could not be updated right now. Try again in a moment.',
+    outlineReviseWaiting: 'Kimi is revising and checking the outline. The current version stays in place until the new one is ready.',
+    outlineReviseSuccess: 'The new outline passed its checks and is ready for your confirmation.',
+    outlineReviseError: 'This change did not finish. The previous outline is intact, and you can retry now.',
     planRevision: 'Outline revision {revision}',
     generate: 'Generate course',
     generating: 'Generating lessons…',
     generationProgress: '{published} of {total} lessons ready',
-    upgradeTitle: 'Ready to go deeper?',
-    upgradeDesc: 'Upgrade to Deep mastery without uploading again — your quick survey stays as the starting point.',
-    upgradeAction: 'Upgrade to Deep',
+    upgradeTitle: 'Deepen this course',
+    upgradeDesc: 'No need to upload again. Kimi will read the source carefully and improve the whole course while keeping existing lessons until replacements pass review.',
+    upgradeAction: 'Deepen course',
     learningTitle: 'Your course is ready',
     lessonsReady: '{published} of {total} lessons published',
     lessonsUnavailable: 'Lesson files are not available yet — they appear here as they are published.',
     lessonLoadError: 'This lesson could not be loaded.',
+    lessonReviseAction: 'Revise this lesson',
+    lessonRegenerateAction: 'Regenerate this lesson',
+    lessonReviseTitle: 'Revise the current lesson in one sentence',
+    lessonRevisePlaceholder: 'Describe how you want this lesson adjusted…',
+    lessonReviseExample: 'For example: add a beginner-friendly example; slow down the second explanation; add a self-check tied to the learning objective.',
+    lessonReviseSubmit: 'Update lesson',
+    lessonActionCancel: 'Cancel',
+    lessonRegenerateConfirmTitle: 'Regenerate the current lesson?',
+    lessonRegenerateConfirmBody: 'Only this lesson will be replaced. The current version stays visible until the replacement passes its checks.',
+    lessonRegenerateConfirmAction: 'Regenerate lesson',
+    lessonReviseWaiting: 'Kimi is revising this lesson. The current version stays in place until the replacement passes its checks.',
+    lessonRegenerateWaiting: 'Kimi is regenerating this lesson. The current version stays in place until the replacement passes its checks.',
+    lessonChangeSuccess: 'The current lesson passed its checks and was updated.',
+    lessonChangeError: 'This update did not finish. The previous lesson is intact, and you can retry now.',
     type_lesson: 'Lesson',
     type_reference: 'Reference',
     type_quiz: 'Quiz',
diff --git a/apps/kimi-web/src/i18n/locales/zh/study.ts b/apps/kimi-web/src/i18n/locales/zh/study.ts
index 6c362f56..e224d558 100644
--- a/apps/kimi-web/src/i18n/locales/zh/study.ts
+++ b/apps/kimi-web/src/i18n/locales/zh/study.ts
@@ -71,21 +71,38 @@ export default {
     outlineDesigning: 'Kimi 正在根据材料和目标设计大纲…',
     outlineCounts: '{chapters} 章 · {pages} 页 · {quizzes} 个测验',
     outlineReviseTitle: '提出修改',
-    outlineRevisePlaceholder: '例如：“加一章关于边界情况的讲解”…',
+    outlineRevisePlaceholder: '用一句话说明你想怎样调整大纲…',
+    outlineReviseExample: '例如：面向零基础读者；先讲案例再讲原理；缩减为 6 节；把风险分析移到最前面。',
     outlineReviseAction: '更新大纲',
     outlineReviseSent: '已提交修改——通过检查后，新的大纲版本会出现在这里。',
-    outlineReviseError: '暂时无法更新大纲，请稍后再试。',
+    outlineReviseWaiting: 'Kimi 正在按你的要求修改并检查大纲，当前版本会保留到新版本就绪。',
+    outlineReviseSuccess: '新大纲已通过检查并更新。请确认后再开始生成课程。',
+    outlineReviseError: '这次修改没有完成，原大纲已保留。你可以直接重试。',
     planRevision: '大纲版本 {revision}',
     generate: '生成课程',
     generating: '正在生成课程…',
     generationProgress: '{total} 节课已就绪 {published} 节',
-    upgradeTitle: '想学得更深？',
-    upgradeDesc: '无需重新上传即可升级为深度精学，快速通读成果会保留为起点。',
-    upgradeAction: '升级为深度精学',
+    upgradeTitle: '深入完善课程',
+    upgradeDesc: '不用重新上传。Kimi 会仔细通读材料并完善整门课，已有课节会保留到新版本通过检查。',
+    upgradeAction: '深入完善',
     learningTitle: '课程已就绪',
     lessonsReady: '已发布 {published} / {total} 节课',
     lessonsUnavailable: '课程文件尚未就绪——发布后会出现在这里。',
     lessonLoadError: '这节课暂时无法加载。',
+    lessonReviseAction: '修改本节',
+    lessonRegenerateAction: '重新生成本节',
+    lessonReviseTitle: '用一句话修改当前课节',
+    lessonRevisePlaceholder: '说明你希望这节课怎样调整…',
+    lessonReviseExample: '例如：补一个零基础也能懂的例子；把第二部分讲得更慢；增加一道对应学习目标的自测题。',
+    lessonReviseSubmit: '更新本节',
+    lessonActionCancel: '取消',
+    lessonRegenerateConfirmTitle: '确定重新生成当前课节？',
+    lessonRegenerateConfirmBody: '只会替换当前课节。新版本通过检查前，你仍然会看到现在的内容。',
+    lessonRegenerateConfirmAction: '确定重新生成',
+    lessonReviseWaiting: 'Kimi 正在按要求修改本节，旧版本会保留到新版本通过检查。',
+    lessonRegenerateWaiting: 'Kimi 正在重新生成本节，旧版本会保留到新版本通过检查。',
+    lessonChangeSuccess: '当前课节已通过检查并更新。',
+    lessonChangeError: '这次更新没有完成，原课节已保留。你可以直接重试。',
     type_lesson: '课程',
     type_reference: '参考',
     type_quiz: '测验',
diff --git a/apps/kimi-web/src/study/StudyApp.vue b/apps/kimi-web/src/study/StudyApp.vue
index 73f75055..8749b757 100644
--- a/apps/kimi-web/src/study/StudyApp.vue
+++ b/apps/kimi-web/src/study/StudyApp.vue
@@ -1,7 +1,6 @@
 <!-- apps/kimi-web/src/study/StudyApp.vue -->
-<!-- Kimi Study product shell. Every screen renders against the product facade
-     (useStudyProduct) and the pure screen mapper — never against raw sessions,
-     models, permissions, or chat state. -->
+<!-- Kimi Study product shell. The core path is deliberately narrow:
+     upload material, generate with Quick, optionally deepen, then learn. -->
 <script setup lang="ts">
 import { computed, onMounted, provide, ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
@@ -14,19 +13,15 @@ import {
   deriveStudyScreen,
   STUDY_PRODUCT_INJECTION_KEY,
   useStudyProduct,
-  type CertifiedCatalogMaterial,
   type QuestionResponse,
   type StudyCourseBinding,
 } from './foundation';
 import StudyProductHome from './components/product/StudyProductHome.vue';
-import StudyModeSelect from './components/product/StudyModeSelect.vue';
 import StudyPreparing from './components/product/StudyPreparing.vue';
 import StudyOutline from './components/product/StudyOutline.vue';
 import StudyLearning from './components/product/StudyLearning.vue';
 import StudyQuestionCard from './components/product/StudyQuestionCard.vue';
 
-// Hydrate the server-transport credential (#token fragment or localStorage)
-// before the facade's first REST/WS call, mirroring the chat client's boot.
 initServerAuth();
 
 const { t } = useI18n();
@@ -35,7 +30,6 @@ useAppearance();
 const product = useStudyProduct();
 provide(STUDY_PRODUCT_INJECTION_KEY, product);
 const courses = ref<readonly StudyCourseBinding[]>([]);
-const catalog = ref<readonly CertifiedCatalogMaterial[]>([]);
 
 async function reloadCourses(): Promise<void> {
   try {
@@ -43,11 +37,6 @@ async function reloadCourses(): Promise<void> {
   } catch {
     courses.value = [];
   }
-  try {
-    catalog.value = await product.listCatalog();
-  } catch {
-    catalog.value = [];
-  }
 }
 
 onMounted(async () => {
@@ -63,8 +52,6 @@ const model = computed(() => deriveStudyScreen(product.view.value));
 const snapshot = computed(() => product.view.value.snapshot);
 const question = computed(() => product.view.value.question);
 
-// A 401 from the server means the transport credential is missing/expired —
-// offer a token entry instead of the generic "unreachable" screen.
 const needsServerCredential = computed(() =>
   model.value.screen === 'unavailable'
   && /401|unauthorized/i.test(model.value.readinessMessage ?? ''));
@@ -99,16 +86,16 @@ async function guard(action: () => Promise<unknown>): Promise<void> {
   try {
     await action();
   } catch {
-    // Failures transition the facade to the error screen; nothing to do here.
+    // Failures transition the facade to the error screen.
   }
 }
 
 function onUpload(file: File): Promise<void> {
-  return guard(() => product.upload(file));
-}
-
-function onSelectMode(mode: 'quick' | 'deep'): Promise<void> {
-  return guard(() => product.selectMode(mode));
+  return guard(async () => {
+    await product.upload(file);
+    // Quick is the product default. Deep remains an optional later enhancement.
+    await product.selectMode('quick');
+  });
 }
 
 function onOpen(courseId: string): Promise<void> {
@@ -118,10 +105,6 @@ function onOpen(courseId: string): Promise<void> {
   });
 }
 
-function onStartCatalog(material: CertifiedCatalogMaterial): Promise<void> {
-  return guard(() => product.startCatalog(material));
-}
-
 function onAnswer(response: QuestionResponse): Promise<void> {
   return guard(() => product.answerQuestion(response));
 }
@@ -206,22 +189,19 @@ function onRecheck(): Promise<void> {
       <StudyProductHome
         v-else-if="model.screen === 'home'"
         :courses="courses"
-        :catalog="catalog"
         :busy="model.busy"
         :auth-required="model.authRequired"
         :readiness-message="model.readinessMessage"
         @upload="onUpload"
         @open="onOpen"
-        @catalog="onStartCatalog"
         @recheck="onRecheck"
       />
 
-      <StudyModeSelect
-        v-else-if="model.screen === 'mode_select' && snapshot"
-        :source-title="snapshot.source.title"
-        :busy="model.busy"
-        @select="onSelectMode"
-      />
+      <!-- mode_select is intentionally transient: uploads immediately select Quick. -->
+      <div v-else-if="model.screen === 'mode_select'" class="study-center">
+        <Spinner size="lg" />
+        <p class="study-center-text">{{ t('study.product.loading') }}</p>
+      </div>
 
       <StudyPreparing
         v-else-if="model.screen === 'preparing' && snapshot"
diff --git a/apps/kimi-web/src/study/components/StudyCourseList.vue b/apps/kimi-web/src/study/components/StudyCourseList.vue
index aed50bff..ec91823d 100644
--- a/apps/kimi-web/src/study/components/StudyCourseList.vue
+++ b/apps/kimi-web/src/study/components/StudyCourseList.vue
@@ -133,6 +133,6 @@ function statusText(course: CourseSummary): string {
 
 .course-status-review {
   color: var(--color-accent);
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
 }
 </style>
diff --git a/apps/kimi-web/src/study/components/StudyGenerator.vue b/apps/kimi-web/src/study/components/StudyGenerator.vue
index 2b1d17ef..14e9d96d 100644
--- a/apps/kimi-web/src/study/components/StudyGenerator.vue
+++ b/apps/kimi-web/src/study/components/StudyGenerator.vue
@@ -375,7 +375,7 @@ function openLesson(file: string): void {
   align-items: center;
   gap: var(--space-2);
   font-size: 16px;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
   margin: 0;
 }
 
@@ -388,14 +388,14 @@ function openLesson(file: string): void {
 
 .reading-bar {
   height: 6px;
-  border-radius: 3px;
+  border-radius: var(--radius-xs);
   background: var(--color-surface-sunken);
   overflow: hidden;
 }
 
 .reading-bar-fill {
   height: 100%;
-  border-radius: 3px;
+  border-radius: var(--radius-xs);
   background: var(--color-accent);
   transition: width 0.4s ease;
 }
@@ -423,7 +423,7 @@ function openLesson(file: string): void {
 
 .course-title {
   font-size: 22px;
-  font-weight: 700;
+  font-weight: var(--weight-semibold);
   margin: 0 0 var(--space-3);
   line-height: 1.3;
 }
@@ -489,7 +489,7 @@ function openLesson(file: string): void {
   cursor: pointer;
   list-style: none;
   font-size: 15px;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
 }
 
 .chapter-summary::-webkit-details-marker {
@@ -549,7 +549,7 @@ function openLesson(file: string): void {
 
 .published-title {
   font-size: 13px;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
   color: var(--color-success);
   margin-bottom: var(--space-2);
 }
@@ -601,7 +601,7 @@ function openLesson(file: string): void {
 .chat-rail-title {
   flex: 1;
   min-width: 0;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
@@ -617,8 +617,8 @@ function openLesson(file: string): void {
 /* Coursebox generate button: centred pill, min(400px,100%) × 44, radius 50. */
 .primary-wide {
   width: min(400px, 100%);
-  border-radius: 50px !important;
-  font-weight: 600 !important;
+  border-radius: var(--radius-full);
+  font-weight: var(--weight-semibold) !important;
   transition:
     background 0.15s,
     transform 0.1s !important;
diff --git a/apps/kimi-web/src/study/components/StudyLearner.vue b/apps/kimi-web/src/study/components/StudyLearner.vue
index ade48f3c..0077a9b0 100644
--- a/apps/kimi-web/src/study/components/StudyLearner.vue
+++ b/apps/kimi-web/src/study/components/StudyLearner.vue
@@ -254,7 +254,7 @@ function backToOutline(): void {
 
 .toc-title {
   font-size: 12px;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
   color: var(--color-text-faint);
   padding: 0 6px;
 }
@@ -295,7 +295,7 @@ function backToOutline(): void {
 .toc-item-active {
   background: var(--color-selected);
   color: var(--color-text);
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
 }
 
 .toc-no {
@@ -334,7 +334,7 @@ function backToOutline(): void {
 
 .lesson-band-label {
   flex: none;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
   color: var(--color-accent);
 }
 
@@ -367,7 +367,7 @@ function backToOutline(): void {
   background: var(--color-bg);
   border-left: 1px solid var(--color-line);
   box-shadow: -8px 0 24px rgb(0 0 0 / 8%);
-  z-index: 20;
+  z-index: 1;
 }
 
 .tutor-slide-enter-active,
@@ -391,7 +391,7 @@ function backToOutline(): void {
 
 .tutor-title {
   font-size: 14px;
-  font-weight: 600;
+  font-weight: var(--weight-semibold);
 }
 
 .tutor-context {
diff --git a/apps/kimi-web/src/study/components/product/StudyLearning.vue b/apps/kimi-web/src/study/components/product/StudyLearning.vue
index 7e43ee47..d38698e6 100644
--- a/apps/kimi-web/src/study/components/product/StudyLearning.vue
+++ b/apps/kimi-web/src/study/components/product/StudyLearning.vue
@@ -37,6 +37,7 @@ const { t } = useI18n();
 const product = inject(STUDY_PRODUCT_INJECTION_KEY)!;
 
 const showUpgrade = computed(() => props.snapshot.profile?.mode === 'quick');
+const lessonOperation = computed(() => product.view.value.lessonOperation);
 
 const lessonsLabel = computed(() =>
   t('study.product.lessonsReady', {
@@ -56,6 +57,9 @@ const treeUnavailable = ref(false);
 const treeNavOpen = ref(false);
 const currentPath = ref<string | undefined>(undefined);
 const currentLesson = ref<LessonSource | undefined>(undefined);
+const lessonEditorOpen = ref(false);
+const lessonInstruction = ref('');
+const regenerationConfirmOpen = ref(false);
 let treeLoadEpoch = 0;
 
 async function publishTree(entries: readonly LessonEntry[], epoch: number): Promise<void> {
@@ -126,6 +130,11 @@ async function loadTree(): Promise<void> {
 }
 
 async function selectLesson(path: string): Promise<void> {
+  if (currentPath.value !== path) {
+    lessonEditorOpen.value = false;
+    lessonInstruction.value = '';
+    regenerationConfirmOpen.value = false;
+  }
   currentPath.value = path;
   if (typeof window !== 'undefined' && window.matchMedia('(max-width: 640px)').matches) {
     treeNavOpen.value = false;
@@ -170,6 +179,46 @@ async function nextLesson(): Promise<void> {
   if (entry !== undefined) await selectLesson(entry.path);
 }
 
+const currentLessonOperation = computed(() =>
+  lessonOperation.value.path === currentPath.value ? lessonOperation.value : undefined);
+
+const lessonCanChange = computed(() =>
+  currentPath.value !== undefined
+  && currentLesson.value?.state === 'ok'
+  && !props.busy);
+
+function toggleLessonEditor(): void {
+  lessonEditorOpen.value = !lessonEditorOpen.value;
+  regenerationConfirmOpen.value = false;
+}
+
+async function submitLessonChange(): Promise<void> {
+  const path = currentPath.value;
+  const instruction = lessonInstruction.value.trim();
+  if (path === undefined || instruction.length === 0 || props.busy) return;
+  try {
+    await product.requestLessonChange(path, instruction);
+  } catch {
+    // The controller exposes a recoverable failed state and keeps the reader.
+  }
+}
+
+function askToRegenerateLesson(): void {
+  regenerationConfirmOpen.value = true;
+  lessonEditorOpen.value = false;
+}
+
+async function regenerateLesson(): Promise<void> {
+  const path = currentPath.value;
+  if (path === undefined || props.busy) return;
+  regenerationConfirmOpen.value = false;
+  try {
+    await product.requestLessonRegeneration(path);
+  } catch {
+    // The controller exposes a recoverable failed state and keeps the reader.
+  }
+}
+
 // --- Tutor drawer: page-context questions, answer polling while waiting. ---
 const tutorOpen = ref(false);
 const exchanges = ref<readonly TutorExchange[]>([]);
@@ -233,6 +282,18 @@ async function sendTutor(): Promise<void> {
 onMounted(() => { void loadTree(); });
 onUnmounted(stopTutorPolling);
 watch(() => props.snapshot.generation.publishedLessons, () => { void loadTree(); });
+watch(
+  () => [
+    lessonOperation.value.status,
+    lessonOperation.value.path,
+    lessonOperation.value.resultRevision,
+  ] as const,
+  ([status, path]) => {
+    if (status === 'succeeded' && path !== undefined && path === currentPath.value) {
+      void selectLesson(path);
+    }
+  },
+);
 </script>
 
 <template>
@@ -320,13 +381,110 @@ watch(() => props.snapshot.generation.publishedLessons, () => { void loadTree();
       </aside>
 
       <section class="study-learn-reader" :aria-label="t('study.lessonLabel')">
-        <StudyLessonReader
-          v-if="currentLesson"
-          :source="currentLesson"
-          :show-practice-action="false"
-        />
-        <div v-else class="study-learn-reader-empty">
-          <Spinner size="lg" />
+        <div v-if="currentLesson" class="study-lesson-tools">
+          <div class="study-lesson-tools-actions">
+            <Button
+              variant="secondary"
+              size="sm"
+              :disabled="!lessonCanChange"
+              @click="toggleLessonEditor"
+            >
+              <Icon name="pencil" size="sm" />
+              <span>{{ t('study.product.lessonReviseAction') }}</span>
+            </Button>
+            <Button
+              variant="ghost"
+              size="sm"
+              :disabled="!lessonCanChange"
+              @click="askToRegenerateLesson"
+            >
+              <Icon name="sparkles" size="sm" />
+              <span>{{ t('study.product.lessonRegenerateAction') }}</span>
+            </Button>
+          </div>
+
+          <form
+            v-if="lessonEditorOpen"
+            class="study-lesson-edit"
+            @submit.prevent="submitLessonChange"
+          >
+            <label class="study-lesson-edit-label" for="study-lesson-instruction">
+              {{ t('study.product.lessonReviseTitle') }}
+            </label>
+            <textarea
+              id="study-lesson-instruction"
+              v-model="lessonInstruction"
+              class="study-lesson-edit-input"
+              rows="2"
+              :disabled="busy"
+              :placeholder="t('study.product.lessonRevisePlaceholder')"
+            />
+            <p class="study-lesson-edit-example">{{ t('study.product.lessonReviseExample') }}</p>
+            <div class="study-lesson-edit-actions">
+              <Button variant="ghost" size="sm" type="button" :disabled="busy" @click="lessonEditorOpen = false">
+                {{ t('study.product.lessonActionCancel') }}
+              </Button>
+              <Button
+                variant="primary"
+                size="sm"
+                type="submit"
+                :disabled="lessonInstruction.trim().length === 0"
+                :loading="currentLessonOperation?.status === 'submitting' || currentLessonOperation?.status === 'waiting'"
+              >
+                {{ t('study.product.lessonReviseSubmit') }}
+              </Button>
+            </div>
+          </form>
+
+          <div v-if="regenerationConfirmOpen" class="study-lesson-confirm">
+            <div>
+              <p class="study-lesson-confirm-title">{{ t('study.product.lessonRegenerateConfirmTitle') }}</p>
+              <p class="study-lesson-confirm-copy">{{ t('study.product.lessonRegenerateConfirmBody') }}</p>
+            </div>
+            <div class="study-lesson-edit-actions">
+              <Button variant="ghost" size="sm" :disabled="busy" @click="regenerationConfirmOpen = false">
+                {{ t('study.product.lessonActionCancel') }}
+              </Button>
+              <Button variant="secondary" size="sm" :disabled="busy" @click="regenerateLesson">
+                {{ t('study.product.lessonRegenerateConfirmAction') }}
+              </Button>
+            </div>
+          </div>
+
+          <p
+            v-if="currentLessonOperation?.status === 'submitting' || currentLessonOperation?.status === 'waiting'"
+            class="study-lesson-operation is-working"
+            aria-live="polite"
+          >
+            {{ currentLessonOperation.kind === 'revise'
+              ? t('study.product.lessonReviseWaiting')
+              : t('study.product.lessonRegenerateWaiting') }}
+          </p>
+          <p
+            v-else-if="currentLessonOperation?.status === 'succeeded'"
+            class="study-lesson-operation is-success"
+            aria-live="polite"
+          >
+            {{ t('study.product.lessonChangeSuccess') }}
+          </p>
+          <p
+            v-else-if="currentLessonOperation?.status === 'failed'"
+            class="study-lesson-operation is-error"
+            role="alert"
+          >
+            {{ t('study.product.lessonChangeError') }}
+          </p>
+        </div>
+
+        <div class="study-learn-reader-content">
+          <StudyLessonReader
+            v-if="currentLesson"
+            :source="currentLesson"
+            :show-practice-action="false"
+          />
+          <div v-else class="study-learn-reader-empty">
+            <Spinner size="lg" />
+          </div>
         </div>
       </section>
 
@@ -522,6 +680,14 @@ watch(() => props.snapshot.generation.publishedLessons, () => { void loadTree();
 .study-learn-reader {
   flex: 1;
   min-width: 0;
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+}
+
+.study-learn-reader-content {
+  flex: 1;
+  min-height: 0;
   overflow: hidden;
 }
 
@@ -532,6 +698,78 @@ watch(() => props.snapshot.generation.publishedLessons, () => { void loadTree();
   height: 100%;
 }
 
+.study-lesson-tools {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-2);
+  flex: none;
+  padding: var(--space-3) var(--space-4);
+  border-bottom: 1px solid var(--color-line);
+  background: var(--color-surface);
+}
+
+.study-lesson-tools-actions,
+.study-lesson-edit-actions {
+  display: flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: var(--space-2);
+  flex-wrap: wrap;
+}
+
+.study-lesson-edit,
+.study-lesson-confirm {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-2);
+  padding: var(--space-3);
+  border: 1px solid var(--color-line);
+  border-radius: var(--radius-md);
+  background: var(--color-bg);
+}
+
+.study-lesson-edit-label,
+.study-lesson-confirm-title {
+  font-size: var(--text-sm);
+  font-weight: var(--weight-medium);
+  color: var(--color-text);
+}
+
+.study-lesson-edit-input {
+  width: 100%;
+  resize: vertical;
+  min-height: 64px;
+  padding: var(--space-2) var(--space-3);
+  border: 1px solid var(--color-line);
+  border-radius: var(--radius-md);
+  background: var(--color-surface);
+  color: var(--color-text);
+  font-family: var(--font-ui);
+  font-size: var(--text-sm);
+  line-height: var(--leading-relaxed);
+}
+
+.study-lesson-edit-input:focus {
+  outline: none;
+  border-color: var(--color-accent-bd);
+}
+
+.study-lesson-edit-example,
+.study-lesson-confirm-copy,
+.study-lesson-operation {
+  font-size: var(--text-xs);
+  color: var(--color-text-muted);
+  line-height: var(--leading-relaxed);
+}
+
+.study-lesson-operation.is-success {
+  color: var(--color-success);
+}
+
+.study-lesson-operation.is-error {
+  color: var(--color-danger);
+}
+
 .study-tutor {
   width: 360px;
   flex: none;
diff --git a/apps/kimi-web/src/study/components/product/StudyModeSelect.vue b/apps/kimi-web/src/study/components/product/StudyModeSelect.vue
deleted file mode 100644
index 29d4714a..00000000
--- a/apps/kimi-web/src/study/components/product/StudyModeSelect.vue
+++ /dev/null
@@ -1,141 +0,0 @@
-<!-- apps/kimi-web/src/study/components/product/StudyModeSelect.vue -->
-<!-- One-time Quick/Deep decision shown after a successful upload. Catalog
-     courses never render this screen: their source work is already certified. -->
-<script setup lang="ts">
-import { useI18n } from 'vue-i18n';
-import Card from '../../../components/ui/Card.vue';
-import Icon from '../../../components/ui/Icon.vue';
-import Badge from '../../../components/ui/Badge.vue';
-
-defineProps<{
-  sourceTitle: string;
-  busy: boolean;
-}>();
-
-const emit = defineEmits<{
-  select: [mode: 'quick' | 'deep'];
-}>();
-
-const { t } = useI18n();
-</script>
-
-<template>
-  <div class="study-mode">
-    <header class="study-mode-head">
-      <h1 class="study-mode-title">{{ t('study.product.modeTitle', { title: sourceTitle }) }}</h1>
-      <p class="study-mode-hint">{{ t('study.product.modeHint') }}</p>
-    </header>
-
-    <div class="study-mode-cards">
-      <Card
-        class="study-mode-card"
-        :class="{ 'is-disabled': busy }"
-        tabindex="0"
-        role="button"
-        @click="emit('select', 'quick')"
-        @keydown.enter="emit('select', 'quick')"
-      >
-        <div class="study-mode-card-head">
-          <Icon name="bolt" size="md" />
-          <span class="study-mode-card-title">{{ t('study.product.quickTitle') }}</span>
-          <Badge variant="info" size="sm">{{ t('study.product.recommended') }}</Badge>
-        </div>
-        <p class="study-mode-card-desc">{{ t('study.product.quickDesc') }}</p>
-      </Card>
-
-      <Card
-        class="study-mode-card"
-        :class="{ 'is-disabled': busy }"
-        tabindex="0"
-        role="button"
-        @click="emit('select', 'deep')"
-        @keydown.enter="emit('select', 'deep')"
-      >
-        <div class="study-mode-card-head">
-          <Icon name="graduation-cap" size="md" />
-          <span class="study-mode-card-title">{{ t('study.product.deepTitle') }}</span>
-        </div>
-        <p class="study-mode-card-desc">{{ t('study.product.deepDesc') }}</p>
-      </Card>
-    </div>
-
-    <p v-if="busy" class="study-mode-starting">{{ t('study.product.starting') }}</p>
-  </div>
-</template>
-
-<style scoped>
-.study-mode {
-  display: flex;
-  flex-direction: column;
-  gap: var(--space-5);
-  max-width: 720px;
-  margin: 0 auto;
-  padding: var(--space-6) var(--space-4);
-}
-
-.study-mode-head {
-  display: flex;
-  flex-direction: column;
-  gap: var(--space-2);
-}
-
-.study-mode-title {
-  font-size: var(--text-xl);
-  font-weight: var(--weight-semibold);
-  line-height: var(--leading-tight);
-  color: var(--color-text);
-}
-
-.study-mode-hint {
-  font-size: var(--text-sm);
-  color: var(--color-text-muted);
-}
-
-.study-mode-cards {
-  display: grid;
-  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
-  gap: var(--space-4);
-}
-
-.study-mode-card {
-  display: flex;
-  flex-direction: column;
-  gap: var(--space-3);
-  cursor: pointer;
-  transition: border-color var(--duration-fast) var(--ease-out);
-}
-
-.study-mode-card:hover {
-  border-color: var(--color-accent-bd);
-}
-
-.study-mode-card.is-disabled {
-  pointer-events: none;
-  opacity: 0.6;
-}
-
-.study-mode-card-head {
-  display: flex;
-  align-items: center;
-  gap: var(--space-2);
-  color: var(--color-text-muted);
-}
-
-.study-mode-card-title {
-  flex: 1;
-  font-size: var(--text-base);
-  font-weight: var(--weight-semibold);
-  color: var(--color-text);
-}
-
-.study-mode-card-desc {
-  font-size: var(--text-sm);
-  color: var(--color-text-muted);
-  line-height: var(--leading-relaxed);
-}
-
-.study-mode-starting {
-  font-size: var(--text-sm);
-  color: var(--color-text-muted);
-}
-</style>
diff --git a/apps/kimi-web/src/study/components/product/StudyOutline.vue b/apps/kimi-web/src/study/components/product/StudyOutline.vue
index 2f265bcf..d9d0f04b 100644
--- a/apps/kimi-web/src/study/components/product/StudyOutline.vue
+++ b/apps/kimi-web/src/study/components/product/StudyOutline.vue
@@ -9,9 +9,11 @@
 import { computed, inject, onMounted, ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
 import Button from '../../../components/ui/Button.vue';
+import Banner from '../../../components/ui/Banner.vue';
 import Card from '../../../components/ui/Card.vue';
 import Icon from '../../../components/ui/Icon.vue';
 import Badge from '../../../components/ui/Badge.vue';
+import Textarea from '../../../components/ui/Textarea.vue';
 import {
   parseQuickPlanOutline,
   QUICK_PLAN_PATH,
@@ -54,14 +56,29 @@ const revisionLabel = computed(() => {
 });
 
 // --- Outline items from the workspace plan artifact (quick survey plans). ---
-const outline = ref<CourseOutline | undefined>(undefined);
+const loadedOutline = ref<{
+  readonly revision: string;
+  readonly outline: CourseOutline;
+} | undefined>(undefined);
+const outline = computed(() => {
+  const loaded = loadedOutline.value;
+  if (loaded === undefined || loaded.revision !== props.snapshot.plan.revision) return undefined;
+  return loaded.outline;
+});
+let outlineLoadEpoch = 0;
 
 async function loadOutlineItems(): Promise<void> {
-  outline.value = undefined;
-  if (!planReady.value) return;
+  const epoch = ++outlineLoadEpoch;
+  const revision = props.snapshot.plan.revision;
+  if (!planReady.value || revision === undefined) {
+    loadedOutline.value = undefined;
+    return;
+  }
   const loaded = await product.loadCourseText(QUICK_PLAN_PATH);
+  if (epoch !== outlineLoadEpoch || props.snapshot.plan.revision !== revision) return;
   if (loaded.status !== 'ready') return;
-  outline.value = parseQuickPlanOutline(loaded.content);
+  const parsed = parseQuickPlanOutline(loaded.content);
+  if (parsed !== undefined) loadedOutline.value = { revision, outline: parsed };
 }
 
 onMounted(() => { void loadOutlineItems(); });
@@ -69,23 +86,22 @@ watch(() => props.snapshot.plan.revision, () => { void loadOutlineItems(); });
 
 // --- Revisioned outline edits: every request targets the visible revision. ---
 const reviseText = ref('');
-const reviseSent = ref(false);
-const reviseError = ref(false);
-const revising = ref(false);
+const planChange = computed(() => product.view.value.planChange);
+const revising = computed(() =>
+  planChange.value.status === 'submitting' || planChange.value.status === 'waiting');
+
+watch(() => planChange.value.status, (status) => {
+  if (status === 'succeeded') reviseText.value = '';
+});
 
 async function submitRevision(): Promise<void> {
   const text = reviseText.value.trim();
   if (text.length === 0 || revising.value) return;
-  revising.value = true;
-  reviseError.value = false;
   try {
     await product.requestPlanChange(text);
-    reviseText.value = '';
-    reviseSent.value = true;
   } catch {
-    reviseError.value = true;
-  } finally {
-    revising.value = false;
+    // The controller preserves the previous outline and exposes a retryable
+    // failed state. Keep the learner's instruction in the textarea.
   }
 }
 </script>
@@ -150,24 +166,32 @@ async function submitRevision(): Promise<void> {
           <Icon name="file-edit" size="md" />
           <span class="study-outline-revise-title">{{ t('study.product.outlineReviseTitle') }}</span>
         </div>
-        <textarea
+        <Textarea
           v-model="reviseText"
-          class="study-outline-revise-input"
-          rows="2"
+          :rows="2"
           :placeholder="t('study.product.outlineRevisePlaceholder')"
+          :aria-label="t('study.product.outlineReviseTitle')"
+          :disabled="busy"
+          :error="planChange.status === 'failed'"
           @keydown.enter.exact.prevent="submitRevision"
         />
+        <p class="study-outline-revise-example">
+          {{ t('study.product.outlineReviseExample') }}
+        </p>
+        <Banner v-if="planChange.status === 'waiting'" variant="info">
+          {{ t('study.product.outlineReviseWaiting') }}
+        </Banner>
+        <Banner v-else-if="planChange.status === 'succeeded'" variant="info">
+          {{ t('study.product.outlineReviseSuccess') }}
+        </Banner>
+        <Banner v-else-if="planChange.status === 'failed'" variant="danger">
+          {{ t('study.product.outlineReviseError') }}
+        </Banner>
         <div class="study-outline-revise-actions">
-          <p v-if="reviseSent" class="study-outline-revise-note">
-            {{ t('study.product.outlineReviseSent') }}
-          </p>
-          <p v-else-if="reviseError" class="study-outline-revise-note study-outline-revise-note--error">
-            {{ t('study.product.outlineReviseError') }}
-          </p>
           <Button
             variant="secondary"
             size="sm"
-            :disabled="reviseText.trim().length === 0"
+            :disabled="reviseText.trim().length === 0 || busy"
             :loading="revising"
             @click="submitRevision"
           >
@@ -353,22 +377,10 @@ async function submitRevision(): Promise<void> {
   color: var(--color-text);
 }
 
-.study-outline-revise-input {
-  width: 100%;
-  resize: vertical;
-  padding: var(--space-3);
-  border: 1px solid var(--color-line);
-  border-radius: var(--radius-md);
-  background: var(--color-surface);
-  color: var(--color-text);
-  font-family: var(--font-ui);
-  font-size: var(--text-sm);
-  line-height: var(--leading-relaxed);
-}
-
-.study-outline-revise-input:focus {
-  outline: none;
-  border-color: var(--color-accent-bd);
+.study-outline-revise-example {
+  font-size: var(--text-xs);
+  line-height: var(--leading-normal);
+  color: var(--color-text-muted);
 }
 
 .study-outline-revise-actions {
@@ -378,16 +390,6 @@ async function submitRevision(): Promise<void> {
   gap: var(--space-3);
 }
 
-.study-outline-revise-note {
-  flex: 1;
-  font-size: var(--text-xs);
-  color: var(--color-text-muted);
-}
-
-.study-outline-revise-note--error {
-  color: var(--color-danger, var(--color-text-muted));
-}
-
 .study-upgrade {
   display: flex;
   align-items: center;
diff --git a/apps/kimi-web/src/study/components/product/StudyProductHome.vue b/apps/kimi-web/src/study/components/product/StudyProductHome.vue
index 64509851..fddc5654 100644
--- a/apps/kimi-web/src/study/components/product/StudyProductHome.vue
+++ b/apps/kimi-web/src/study/components/product/StudyProductHome.vue
@@ -1,6 +1,5 @@
 <!-- apps/kimi-web/src/study/components/product/StudyProductHome.vue -->
-<!-- Kimi Study home: material upload entry plus resumable course list.
-     No topic-prompt start — courses begin from real learner material. -->
+<!-- Kimi Study core home: one material upload entry and resumable courses. -->
 <script setup lang="ts">
 import { ref } from 'vue';
 import { useI18n } from 'vue-i18n';
@@ -8,11 +7,10 @@ import Button from '../../../components/ui/Button.vue';
 import Card from '../../../components/ui/Card.vue';
 import Icon from '../../../components/ui/Icon.vue';
 import Badge from '../../../components/ui/Badge.vue';
-import type { CertifiedCatalogMaterial, StudyCourseBinding } from '../../foundation';
+import type { StudyCourseBinding } from '../../foundation';
 
 const props = defineProps<{
   courses: readonly StudyCourseBinding[];
-  catalog: readonly CertifiedCatalogMaterial[];
   busy: boolean;
   authRequired: boolean;
   readinessMessage?: string;
@@ -21,12 +19,10 @@ const props = defineProps<{
 const emit = defineEmits<{
   upload: [file: File];
   open: [courseId: string];
-  catalog: [material: CertifiedCatalogMaterial];
   recheck: [];
 }>();
 
 const { t } = useI18n();
-
 const fileInput = ref<HTMLInputElement | null>(null);
 
 function pickFile(): void {
@@ -87,31 +83,6 @@ function formatUpdated(iso: string): string {
       <p class="study-hero-formats">{{ t('study.product.uploadFormats') }}</p>
     </section>
 
-    <section v-if="catalog.length > 0" class="study-courses">
-      <h2 class="study-section-title">{{ t('study.product.catalogTitle') }}</h2>
-      <div class="study-course-list">
-        <Card
-          v-for="material in catalog"
-          :key="material.packageRef"
-          class="study-course-item"
-          :class="{ 'is-disabled': authRequired }"
-          tabindex="0"
-          role="button"
-          @click="authRequired || emit('catalog', material)"
-          @keydown.enter="authRequired || emit('catalog', material)"
-        >
-          <div class="study-course-row">
-            <Icon name="graduation-cap" size="md" />
-            <div class="study-course-info">
-              <span class="study-course-title">{{ material.title }}</span>
-            </div>
-            <Badge variant="info" size="sm">{{ t('study.product.courseKindCatalog') }}</Badge>
-            <Icon name="chevron-right" size="md" />
-          </div>
-        </Card>
-      </div>
-    </section>
-
     <section class="study-courses">
       <h2 class="study-section-title">{{ t('study.product.myCourses') }}</h2>
       <div v-if="courses.length > 0" class="study-course-list">
@@ -125,15 +96,13 @@ function formatUpdated(iso: string): string {
           @keydown.enter="emit('open', course.courseId)"
         >
           <div class="study-course-row">
-            <Icon name="book" size="md" />
+            <Icon name="file-text" size="md" />
             <div class="study-course-info">
               <span class="study-course-title">{{ course.title }}</span>
               <span class="study-course-meta">{{ formatUpdated(course.updatedAt) }}</span>
             </div>
             <Badge variant="neutral" size="sm">
-              {{ course.sourceKind === 'catalog'
-                ? t('study.product.courseKindCatalog')
-                : t('study.product.courseKindUpload') }}
+              {{ t('study.product.courseKindUpload') }}
             </Badge>
             <Icon name="chevron-right" size="md" />
           </div>
@@ -245,15 +214,6 @@ function formatUpdated(iso: string): string {
   border-color: var(--color-accent-bd);
 }
 
-.study-course-item.is-disabled {
-  cursor: default;
-  opacity: 0.6;
-}
-
-.study-course-item.is-disabled:hover {
-  border-color: var(--color-line);
-}
-
 .study-course-row {
   display: flex;
   align-items: center;
diff --git a/apps/kimi-web/src/study/composables/useStudyProduct.ts b/apps/kimi-web/src/study/composables/useStudyProduct.ts
index cd59fb60..7fb13390 100644
--- a/apps/kimi-web/src/study/composables/useStudyProduct.ts
+++ b/apps/kimi-web/src/study/composables/useStudyProduct.ts
@@ -51,7 +51,12 @@ export function useStudyProduct(options: UseStudyProductOptions = {}) {
     // exact StudyProductView shape (readonly() would deep-freeze nested
     // mutable arrays and break assignability).
     view: computed(() => current.value),
-    isBusy: computed(() => ['uploading', 'starting'].includes(current.value.stage)),
+    isBusy: computed(() =>
+      ['uploading', 'starting'].includes(current.value.stage)
+      || current.value.planChange.status === 'submitting'
+      || current.value.planChange.status === 'waiting'
+      || current.value.lessonOperation.status === 'submitting'
+      || current.value.lessonOperation.status === 'waiting'),
     upload: controller.upload.bind(controller),
     selectMode: controller.selectMode.bind(controller),
     startCatalog: controller.startCatalog.bind(controller),
@@ -71,6 +76,8 @@ export function useStudyProduct(options: UseStudyProductOptions = {}) {
     sendTutorMessage: controller.sendTutorMessage.bind(controller),
     listTutorExchanges: controller.listTutorExchanges.bind(controller),
     requestPlanChange: controller.requestPlanChange.bind(controller),
+    requestLessonChange: controller.requestLessonChange.bind(controller),
+    requestLessonRegeneration: controller.requestLessonRegeneration.bind(controller),
   };
 }
 
diff --git a/apps/kimi-web/src/study/domain/lessonRevision.ts b/apps/kimi-web/src/study/domain/lessonRevision.ts
new file mode 100644
index 00000000..d08477a6
--- /dev/null
+++ b/apps/kimi-web/src/study/domain/lessonRevision.ts
@@ -0,0 +1,22 @@
+/** Stable, cross-language identity for one published lesson artifact. */
+
+const LESSON_PATH = /^lessons\/[a-zA-Z0-9][a-zA-Z0-9._-]*\.html$/;
+
+export function isLessonArtifactPath(path: string): boolean {
+  return LESSON_PATH.test(path);
+}
+
+/**
+ * FNV-1a over UTF-8 bytes. The bundled Skills implement the same small hash,
+ * so a stale agent turn can be rejected immediately before atomic replace.
+ * This is an identity token, not a cryptographic integrity claim.
+ */
+export function lessonArtifactRevision(source: string): string {
+  let hash = 0x811c9dc5;
+  for (const byte of new TextEncoder().encode(source)) {
+    hash ^= byte;
+    hash = Math.imul(hash, 0x01000193);
+  }
+  const unsignedHash = hash < 0 ? hash + 0x1_0000_0000 : hash;
+  return `fnv1a32:${unsignedHash.toString(16).padStart(8, '0')}`;
+}
diff --git a/apps/kimi-web/src/study/domain/studyPolicy.ts b/apps/kimi-web/src/study/domain/studyPolicy.ts
index 0581f974..4230aaeb 100644
--- a/apps/kimi-web/src/study/domain/studyPolicy.ts
+++ b/apps/kimi-web/src/study/domain/studyPolicy.ts
@@ -10,11 +10,11 @@ import { STUDY_PRODUCT_CONTRACT_REVISION } from './courseContract';
 export const STUDY_SKILL_PINS: Readonly<Record<'quick' | 'deep', StudySkillPin>> = {
   quick: {
     name: 'teach-quick',
-    contractRevision: 'teach-quick-v2',
+    contractRevision: 'teach-quick-v4',
   },
   deep: {
     name: 'teach-ria',
-    contractRevision: 'teach-ria-v2',
+    contractRevision: 'teach-ria-v4',
   },
 };
 
@@ -54,7 +54,7 @@ const PUBLIC_COPY_FORBIDDEN = [
   /\bskill\s+(?:pin|activation|directory)\b/i,
   /\bactivateSkill\b/i,
   /\bRIA\b/i,
-  /\bV[123]\b/i,
+  /\bV\d+\b/i,
   /\bA[12]\b/i,
   /\bchecker\b/i,
   /\bBOOK-READING-STATE\b/i,
@@ -95,6 +95,7 @@ export function buildSkillActivationArgs(context: SkillActivationContext): strin
     'Keep source/STUDY-SNAPSHOT.json current after every durable state transition.',
     'Never ask the learner to approve internal analysis; record automatic approvals with actor=auto_policy.',
     'Use AskUserQuestion for learner questions, exactly one question per card, with 2-4 options.',
+    'Write learner-facing lessons in natural Chinese, keep source claims traceable, and label teaching examples separately from source facts.',
   ];
 
   if (context.profile.mode === 'quick') {
diff --git a/apps/kimi-web/src/study/foundation.ts b/apps/kimi-web/src/study/foundation.ts
index 4f140921..fec8a6af 100644
--- a/apps/kimi-web/src/study/foundation.ts
+++ b/apps/kimi-web/src/study/foundation.ts
@@ -40,9 +40,19 @@ export type {
 
 export type { LessonSource, LessonStatus } from './domain/lessonDocument';
 
+export {
+  isLessonArtifactPath,
+  lessonArtifactRevision,
+} from './domain/lessonRevision';
+
 export type { TutorExchange } from './domain/tutorThread';
 
 export type {
+  StudyLessonOperationKind,
+  StudyLessonOperationState,
+  StudyLessonOperationStatus,
+  StudyPlanChangeState,
+  StudyPlanChangeStatus,
   StudyProductStage,
   StudyProductView,
 } from './product/studyProductController';
diff --git a/apps/kimi-web/src/study/product/studyProductController.ts b/apps/kimi-web/src/study/product/studyProductController.ts
index 834880da..da29014f 100644
--- a/apps/kimi-web/src/study/product/studyProductController.ts
+++ b/apps/kimi-web/src/study/product/studyProductController.ts
@@ -11,6 +11,7 @@ import {
   createUploadCourse,
 } from '../domain/courseState';
 import { buildTutorThread, type TutorExchange } from '../domain/tutorThread';
+import { isLessonArtifactPath, lessonArtifactRevision } from '../domain/lessonRevision';
 import type { StudyCourseBinding } from '../runtime/courseRegistry';
 import type {
   StudyQuestion,
@@ -30,6 +31,38 @@ export type StudyProductStage =
   | 'ready'
   | 'error';
 
+export type StudyPlanChangeStatus =
+  | 'idle'
+  | 'submitting'
+  | 'waiting'
+  | 'succeeded'
+  | 'failed';
+
+export interface StudyPlanChangeState {
+  readonly status: StudyPlanChangeStatus;
+  /** The immutable plan revision named by the learner's request. */
+  readonly baseRevision?: string;
+  /** The authoritative replacement revision after the Skill finishes. */
+  readonly resultRevision?: string;
+}
+
+export type StudyLessonOperationStatus =
+  | 'idle'
+  | 'submitting'
+  | 'waiting'
+  | 'succeeded'
+  | 'failed';
+
+export type StudyLessonOperationKind = 'revise' | 'regenerate';
+
+export interface StudyLessonOperationState {
+  readonly status: StudyLessonOperationStatus;
+  readonly kind?: StudyLessonOperationKind;
+  readonly path?: string;
+  readonly baseRevision?: string;
+  readonly resultRevision?: string;
+}
+
 export interface StudyProductView {
   readonly stage: StudyProductStage;
   readonly snapshot: CourseSnapshot | null;
@@ -38,6 +71,8 @@ export interface StudyProductView {
   readonly readiness: StudyRuntimeReadiness | null;
   readonly connected: boolean;
   readonly issues: readonly ContractIssue[];
+  readonly planChange: StudyPlanChangeState;
+  readonly lessonOperation: StudyLessonOperationState;
 }
 
 type Listener = (view: StudyProductView) => void;
@@ -45,6 +80,7 @@ type Listener = (view: StudyProductView) => void;
 export interface StudyProductControllerOptions {
   readonly createCourseId?: () => string;
   readonly now?: () => string;
+  readonly createOperationId?: () => string;
   /**
    * Backoff delays (ms) between snapshot reloads while a course artifact is
    * still pending. The number of entries bounds the retries; tests pass [].
@@ -53,6 +89,33 @@ export interface StudyProductControllerOptions {
 }
 
 const DEFAULT_MISSING_RETRY_DELAYS: readonly number[] = [300, 700];
+const IDLE_PLAN_CHANGE: StudyPlanChangeState = { status: 'idle' };
+const IDLE_LESSON_OPERATION: StudyLessonOperationState = { status: 'idle' };
+
+interface PendingPlanChange {
+  readonly courseId: string;
+  readonly baseRevision: string;
+  readonly instruction: string;
+  submission: Promise<void>;
+}
+
+interface PendingLessonOperation {
+  readonly courseId: string;
+  readonly path: string;
+  readonly kind: StudyLessonOperationKind;
+  readonly instruction?: string;
+  readonly operationId: string;
+  baseRevision?: string;
+  submission: Promise<void>;
+}
+
+function isPlanChangeBusy(change: StudyPlanChangeState): boolean {
+  return change.status === 'submitting' || change.status === 'waiting';
+}
+
+function isLessonOperationBusy(operation: StudyLessonOperationState): boolean {
+  return operation.status === 'submitting' || operation.status === 'waiting';
+}
 
 function delay(ms: number): Promise<void> {
   return new Promise((resolve) => { setTimeout(resolve, ms); });
@@ -64,6 +127,12 @@ function defaultCourseId(): string {
   return `course-${id}`.toLowerCase();
 }
 
+function defaultOperationId(): string {
+  const id = globalThis.crypto?.randomUUID?.()
+    ?? `${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 12)}`;
+  return `lesson-op-${id}`.toLowerCase();
+}
+
 function toIssue(code: string, message: string): ContractIssue {
   return { code, path: '', message, severity: 'error' };
 }
@@ -77,9 +146,12 @@ export class StudyProductController {
     readiness: null,
     connected: false,
     issues: [],
+    planChange: IDLE_PLAN_CHANGE,
+    lessonOperation: IDLE_LESSON_OPERATION,
   };
   private readonly listeners = new Set<Listener>();
   private readonly createCourseId: () => string;
+  private readonly createOperationId: () => string;
   private readonly now: () => string;
   private readonly missingRetryDelays: readonly number[];
   private uploadedMaterial: UploadedMaterial | undefined;
@@ -89,12 +161,21 @@ export class StudyProductController {
    * results arriving from an older context are dropped instead of committed.
    */
   private contextEpoch = 0;
+  /** Latest snapshot read in the active course context wins. */
+  private snapshotLoadEpoch = 0;
+  private pendingPlanChange: PendingPlanChange | undefined;
+  private pendingLessonOperation: PendingLessonOperation | undefined;
+  /** Set only by a real session-idle event while a plan change is pending. */
+  private planChangeIdle:
+    | { readonly courseId: string; readonly baseRevision: string }
+    | undefined;
 
   constructor(
     private readonly runtime: StudyRuntimePort,
     options: StudyProductControllerOptions = {},
   ) {
     this.createCourseId = options.createCourseId ?? defaultCourseId;
+    this.createOperationId = options.createOperationId ?? defaultOperationId;
     this.now = options.now ?? (() => new Date().toISOString());
     this.missingRetryDelays = options.missingRetryDelays ?? DEFAULT_MISSING_RETRY_DELAYS;
   }
@@ -137,12 +218,19 @@ export class StudyProductController {
       binding: null,
       question: null,
       issues: [],
+      planChange: IDLE_PLAN_CHANGE,
+      lessonOperation: IDLE_LESSON_OPERATION,
     });
   }
 
   async upload(file: File): Promise<CourseSnapshot> {
     const epoch = this.nextContext();
-    this.update({ stage: 'uploading', issues: [] });
+    this.update({
+      stage: 'uploading',
+      issues: [],
+      planChange: IDLE_PLAN_CHANGE,
+      lessonOperation: IDLE_LESSON_OPERATION,
+    });
     try {
       const material = await this.runtime.uploadMaterial(file);
       if (!this.isCurrent(epoch)) throw new Error('Study upload was superseded.');
@@ -185,7 +273,15 @@ export class StudyProductController {
     const epoch = this.nextContext();
     this.uploadedMaterial = undefined;
     const snapshot = createCatalogCourse(this.createCourseId(), material, this.now());
-    this.update({ stage: 'starting', snapshot, binding: null, question: null, issues: [] });
+    this.update({
+      stage: 'starting',
+      snapshot,
+      binding: null,
+      question: null,
+      issues: [],
+      planChange: IDLE_PLAN_CHANGE,
+      lessonOperation: IDLE_LESSON_OPERATION,
+    });
     try {
       const binding = await this.runtime.startCourse({ snapshot, catalogMaterial: material });
       if (!this.isCurrent(epoch, snapshot.courseId)) return;
@@ -204,7 +300,13 @@ export class StudyProductController {
     if (binding === undefined) return false;
     if (!this.isCurrent(epoch)) return false;
     this.uploadedMaterial = binding.uploadedMaterial;
-    this.update({ binding, stage: 'working', issues: [] });
+    this.update({
+      binding,
+      stage: 'working',
+      issues: [],
+      planChange: IDLE_PLAN_CHANGE,
+      lessonOperation: IDLE_LESSON_OPERATION,
+    });
     await this.attachWatcher(courseId, epoch);
     await this.refreshUntilSettled(courseId, epoch);
     return true;
@@ -223,9 +325,31 @@ export class StudyProductController {
     courseId: string,
     epoch: number,
   ): Promise<'ready' | 'missing' | 'invalid' | 'stale'> {
+    const loadEpoch = ++this.snapshotLoadEpoch;
     const loaded = await this.runtime.loadSnapshot(courseId);
-    if (!this.isCurrent(epoch, courseId)) return 'stale';
+    if (!this.isCurrent(epoch, courseId) || loadEpoch !== this.snapshotLoadEpoch) return 'stale';
     if (loaded.status === 'ready') {
+      const currentChange = this.viewState.planChange;
+      let planChange = currentChange;
+      if (isPlanChangeBusy(currentChange) && currentChange.baseRevision !== undefined) {
+        const nextRevision = loaded.snapshot.plan.status === 'ready'
+          ? loaded.snapshot.plan.revision
+          : undefined;
+        if (nextRevision !== undefined && nextRevision !== currentChange.baseRevision) {
+          planChange = {
+            status: 'succeeded',
+            baseRevision: currentChange.baseRevision,
+            resultRevision: nextRevision,
+          };
+          this.pendingPlanChange = undefined;
+          this.planChangeIdle = undefined;
+        } else if (this.failPlanChangeAtIdle(courseId, currentChange)) {
+          // A real session-idle event was recorded for this request. Reaching
+          // idle without a new ready revision is a recoverable
+          // plan-edit failure; the previous authoritative snapshot stays put.
+          planChange = this.viewState.planChange;
+        }
+      }
       this.update({
         snapshot: loaded.snapshot,
         stage: this.viewState.question === null
@@ -233,10 +357,15 @@ export class StudyProductController {
               || loaded.snapshot.generation.status === 'partially_ready' ? 'ready' : 'working')
           : 'question',
         issues: [],
+        planChange,
       });
       return 'ready';
     }
-    if (loaded.status === 'missing') return 'missing';
+    if (loaded.status === 'missing') {
+      this.failPlanChangeAtIdle(courseId, this.viewState.planChange);
+      return 'missing';
+    }
+    if (this.failPlanChangeAtIdle(courseId, this.viewState.planChange)) return 'invalid';
     this.update({ stage: 'error', issues: loaded.issues });
     return 'invalid';
   }
@@ -302,11 +431,23 @@ export class StudyProductController {
 
   async generate(): Promise<void> {
     const snapshot = this.requireSnapshot();
-    if (!snapshot.canGenerate || snapshot.plan.revision === undefined) {
+    const planRevision = snapshot.plan.revision;
+    if (planRevision === undefined) {
+      throw new Error('The current evidence and plan revisions are not ready for generation.');
+    }
+    if (snapshot.generation.planRevision === planRevision
+      && (snapshot.generation.status === 'generating'
+        || snapshot.generation.status === 'partially_ready'
+        || snapshot.generation.status === 'ready')) {
+      // A double-click or replayed event confirms the same revision only once.
+      return;
+    }
+    if (!snapshot.canGenerate
+      || isPlanChangeBusy(this.viewState.planChange)
+      || isLessonOperationBusy(this.viewState.lessonOperation)) {
       throw new Error('The current evidence and plan revisions are not ready for generation.');
     }
     const epoch = this.contextEpoch;
-    const planRevision = snapshot.plan.revision;
     const next = applyCourseEvent(snapshot, {
       type: 'generation_updated',
       generation: {
@@ -336,10 +477,27 @@ export class StudyProductController {
   }
 
   async upgradeToDeep(): Promise<void> {
+    if (this.viewState.stage === 'starting') return;
     const current = this.requireSnapshot();
-    const epoch = this.nextContext();
+    if (current.profile?.mode !== 'quick') {
+      // Replayed clicks after the authoritative profile changes are harmless.
+      if (current.profile?.mode === 'deep' || current.profile?.mode === 'deep_preprocessed') return;
+      throw new Error('Only a ready quick course can be deepened.');
+    }
+    if (isPlanChangeBusy(this.viewState.planChange)
+      || isLessonOperationBusy(this.viewState.lessonOperation)) {
+      throw new Error('Wait for the current course change before deepening the course.');
+    }
     const snapshot = applyCourseEvent(current, { type: 'upgrade_requested' }, this.now());
-    this.update({ snapshot, stage: 'starting', issues: [] });
+    const epoch = this.nextContext();
+    // Keep the last valid Quick snapshot and its published lessons visible
+    // until the Deep Skill publishes an authoritative replacement snapshot.
+    this.update({
+      stage: 'starting',
+      issues: [],
+      planChange: IDLE_PLAN_CHANGE,
+      lessonOperation: IDLE_LESSON_OPERATION,
+    });
     try {
       const binding = await this.runtime.startCourse({
         snapshot,
@@ -367,6 +525,18 @@ export class StudyProductController {
     return this.runtime.listCourseFiles(snapshot.courseId, path);
   }
 
+  /** Revise the visible lesson while its last valid artifact stays readable. */
+  async requestLessonChange(path: string, instruction: string): Promise<void> {
+    const text = instruction.trim();
+    if (text.length === 0) throw new Error('Lesson change request is empty.');
+    await this.beginLessonOperation('revise', path, text);
+  }
+
+  /** Regenerate the visible lesson behind the same identity and source anchors. */
+  async requestLessonRegeneration(path: string): Promise<void> {
+    await this.beginLessonOperation('regenerate', path);
+  }
+
   /** Ask the course tutor; the current page context anchors the answer. */
   async sendTutorMessage(text: string, context: TutorLessonContext = {}): Promise<void> {
     const snapshot = this.requireSnapshot();
@@ -394,7 +564,148 @@ export class StudyProductController {
       throw new Error('Only the current ready outline revision can be revised.');
     }
     if (text.length === 0) throw new Error('Outline change request is empty.');
-    await this.runtime.requestPlanChange(snapshot.courseId, snapshot.plan.revision, text);
+    if (isLessonOperationBusy(this.viewState.lessonOperation)) {
+      throw new Error('Wait for the current lesson change before revising the outline.');
+    }
+
+    const baseRevision = snapshot.plan.revision;
+    const active = this.pendingPlanChange;
+    if (isPlanChangeBusy(this.viewState.planChange)) {
+      if (active?.courseId === snapshot.courseId
+        && active.baseRevision === baseRevision
+        && active.instruction === text) {
+        await active.submission;
+        return;
+      }
+      throw new Error('Another outline change is still in progress.');
+    }
+
+    const epoch = this.contextEpoch;
+    const request: PendingPlanChange = {
+      courseId: snapshot.courseId,
+      baseRevision,
+      instruction: text,
+      submission: Promise.resolve(),
+    };
+    this.pendingPlanChange = request;
+    this.planChangeIdle = undefined;
+    this.update({
+      planChange: { status: 'submitting', baseRevision },
+    });
+    request.submission = Promise.resolve().then(() =>
+      this.runtime.requestPlanChange(snapshot.courseId, baseRevision, text));
+
+    try {
+      await request.submission;
+      if (this.pendingPlanChange === request
+        && this.isCurrent(epoch, snapshot.courseId)
+        && this.viewState.planChange.status === 'submitting') {
+        this.update({ planChange: { status: 'waiting', baseRevision } });
+      }
+    } catch (error) {
+      if (this.pendingPlanChange === request && this.isCurrent(epoch, snapshot.courseId)) {
+        this.pendingPlanChange = undefined;
+        this.planChangeIdle = undefined;
+        this.update({ planChange: { status: 'failed', baseRevision } });
+      }
+      throw error;
+    }
+  }
+
+  private async beginLessonOperation(
+    kind: StudyLessonOperationKind,
+    path: string,
+    instruction?: string,
+  ): Promise<void> {
+    const snapshot = this.requireSnapshot();
+    if (!isLessonArtifactPath(path)) throw new Error('Only a published lesson can be changed.');
+    if (isPlanChangeBusy(this.viewState.planChange)) {
+      throw new Error('Wait for the current outline change before changing a lesson.');
+    }
+
+    const active = this.pendingLessonOperation;
+    if (isLessonOperationBusy(this.viewState.lessonOperation)) {
+      if (active?.courseId === snapshot.courseId
+        && active.path === path
+        && active.kind === kind
+        && active.instruction === instruction) {
+        await active.submission;
+        return;
+      }
+      throw new Error('Another lesson change is still in progress.');
+    }
+
+    const epoch = this.contextEpoch;
+    const request: PendingLessonOperation = {
+      courseId: snapshot.courseId,
+      path,
+      kind,
+      operationId: this.createOperationId(),
+      submission: Promise.resolve(),
+      ...(instruction === undefined ? {} : { instruction }),
+    };
+    this.pendingLessonOperation = request;
+    this.update({ lessonOperation: { status: 'submitting', kind, path } });
+    request.submission = (async () => {
+      const loaded = await this.runtime.readCourseText(snapshot.courseId, path);
+      if (loaded.status !== 'ready' || loaded.truncated) {
+        throw new Error('The current lesson is unavailable or incomplete.');
+      }
+      if (!this.isCurrent(epoch, snapshot.courseId) || this.pendingLessonOperation !== request) return;
+      const baseRevision = lessonArtifactRevision(loaded.content);
+      request.baseRevision = baseRevision;
+      this.update({
+        lessonOperation: {
+          status: 'submitting',
+          kind,
+          path,
+          baseRevision,
+        },
+      });
+      if (kind === 'revise') {
+        await this.runtime.requestLessonChange(
+          snapshot.courseId,
+          path,
+          request.baseRevision,
+          instruction ?? '',
+          request.operationId,
+        );
+      } else {
+        await this.runtime.requestLessonRegeneration(
+          snapshot.courseId,
+          path,
+          request.baseRevision,
+          request.operationId,
+        );
+      }
+    })();
+
+    try {
+      await request.submission;
+      if (this.pendingLessonOperation === request && this.isCurrent(epoch, snapshot.courseId)) {
+        this.update({
+          lessonOperation: {
+            status: 'waiting',
+            kind,
+            path,
+            ...(request.baseRevision === undefined ? {} : { baseRevision: request.baseRevision }),
+          },
+        });
+      }
+    } catch (error) {
+      if (this.pendingLessonOperation === request && this.isCurrent(epoch, snapshot.courseId)) {
+        this.pendingLessonOperation = undefined;
+        this.update({
+          lessonOperation: {
+            status: 'failed',
+            kind,
+            path,
+            ...(request.baseRevision === undefined ? {} : { baseRevision: request.baseRevision }),
+          },
+        });
+      }
+      throw error;
+    }
   }
 
   dispose(): void {
@@ -418,9 +729,16 @@ export class StudyProductController {
           this.update({ question: null, stage: 'working' });
         }
       },
-      onArtifactChanged: () => {
+      onArtifactChanged: (reason) => {
         if (!this.isCurrent(epoch, courseId)) return;
+        const change = this.viewState.planChange;
+        if (reason === 'session_idle'
+          && isPlanChangeBusy(change)
+          && change.baseRevision !== undefined) {
+          this.planChangeIdle = { courseId, baseRevision: change.baseRevision };
+        }
         void this.refreshSnapshot(courseId, epoch);
+        if (reason === 'session_idle') void this.settleLessonOperation(courseId, epoch);
       },
       onConnectionChange: (connected) => {
         if (!this.isCurrent(epoch, courseId)) return;
@@ -445,9 +763,63 @@ export class StudyProductController {
   /** Begin a new async context; results from older contexts get dropped. */
   private nextContext(): number {
     this.contextEpoch += 1;
+    this.snapshotLoadEpoch += 1;
+    this.pendingPlanChange = undefined;
+    this.pendingLessonOperation = undefined;
+    this.planChangeIdle = undefined;
     return this.contextEpoch;
   }
 
+  private async settleLessonOperation(courseId: string, epoch: number): Promise<void> {
+    const request = this.pendingLessonOperation;
+    if (request?.courseId !== courseId || request.baseRevision === undefined) return;
+    const loaded = await this.runtime.readCourseText(courseId, request.path);
+    if (!this.isCurrent(epoch, courseId) || this.pendingLessonOperation !== request) return;
+    if (loaded.status === 'ready' && !loaded.truncated) {
+      const resultRevision = lessonArtifactRevision(loaded.content);
+      if (resultRevision !== request.baseRevision) {
+        this.pendingLessonOperation = undefined;
+        this.update({
+          lessonOperation: {
+            status: 'succeeded',
+            kind: request.kind,
+            path: request.path,
+            baseRevision: request.baseRevision,
+            resultRevision,
+          },
+        });
+        return;
+      }
+    }
+    this.pendingLessonOperation = undefined;
+    this.update({
+      lessonOperation: {
+        status: 'failed',
+        kind: request.kind,
+        path: request.path,
+        baseRevision: request.baseRevision,
+      },
+    });
+  }
+
+  private failPlanChangeAtIdle(
+    courseId: string,
+    change: StudyPlanChangeState,
+  ): boolean {
+    if (!isPlanChangeBusy(change)
+      || change.baseRevision === undefined
+      || this.planChangeIdle?.courseId !== courseId
+      || this.planChangeIdle.baseRevision !== change.baseRevision) {
+      return false;
+    }
+    this.pendingPlanChange = undefined;
+    this.planChangeIdle = undefined;
+    this.update({
+      planChange: { status: 'failed', baseRevision: change.baseRevision },
+    });
+    return true;
+  }
+
   /** True when an async result still belongs to the live course context. */
   private isCurrent(epoch: number, courseId?: string): boolean {
     if (epoch !== this.contextEpoch) return false;
diff --git a/apps/kimi-web/src/study/product/studyScreenModel.ts b/apps/kimi-web/src/study/product/studyScreenModel.ts
index eab059f5..4ea6d878 100644
--- a/apps/kimi-web/src/study/product/studyScreenModel.ts
+++ b/apps/kimi-web/src/study/product/studyScreenModel.ts
@@ -30,7 +30,7 @@ export type StudyScreen =
 
 export interface StudyScreenModel {
   readonly screen: StudyScreen;
-  /** True while a blocking action (upload/start) is in flight. */
+  /** True while upload, start, outline, or current-lesson replacement is in flight. */
   readonly busy: boolean;
   /** Provider login is missing: generation is impossible, browsing is not. */
   readonly authRequired: boolean;
@@ -65,7 +65,12 @@ function screenForPhase(view: StudyProductView): StudyScreen {
 }
 
 export function deriveStudyScreen(view: StudyProductView): StudyScreenModel {
-  const busy = view.stage === 'uploading' || view.stage === 'starting';
+  const busy = view.stage === 'uploading'
+    || view.stage === 'starting'
+    || view.planChange.status === 'submitting'
+    || view.planChange.status === 'waiting'
+    || view.lessonOperation.status === 'submitting'
+    || view.lessonOperation.status === 'waiting';
   const authRequired = view.readiness?.auth === 'required';
   const questionOpen = view.question !== null;
 
diff --git a/apps/kimi-web/src/study/runtime/kimiStudyRuntime.ts b/apps/kimi-web/src/study/runtime/kimiStudyRuntime.ts
index ab0b6958..27095ef7 100644
--- a/apps/kimi-web/src/study/runtime/kimiStudyRuntime.ts
+++ b/apps/kimi-web/src/study/runtime/kimiStudyRuntime.ts
@@ -21,6 +21,7 @@ import type {
 import {
   buildSkillActivationArgs,
 } from '../domain/studyPolicy';
+import { isLessonArtifactPath } from '../domain/lessonRevision';
 import type { StudyCourseBinding, StudyOperationMarker } from './courseRegistry';
 import { StudyCourseRegistry } from './courseRegistry';
 import type {
@@ -70,6 +71,16 @@ function assertArtifactPath(path: string): void {
   }
 }
 
+function assertLessonOperation(lessonPath: string, baseRevision: string, operationId: string): void {
+  if (!isLessonArtifactPath(lessonPath)) throw new Error('Invalid Kimi Study lesson path.');
+  if (!/^fnv1a32:[0-9a-f]{8}$/.test(baseRevision)) {
+    throw new Error('Invalid Kimi Study lesson revision.');
+  }
+  if (!/^[a-zA-Z0-9][a-zA-Z0-9._:-]{7,127}$/.test(operationId)) {
+    throw new Error('Invalid Kimi Study lesson operation id.');
+  }
+}
+
 /** Small deterministic digest for idempotent plan-edit operation ids. */
 function operationDigest(text: string): string {
   let hash = 5381;
@@ -94,14 +105,16 @@ function isOperationMessage(message: AppMessage, expected: string): boolean {
   return message.metadata?.['kimiStudyOperationId'] === expected;
 }
 
-/**
- * v1 -> v2 migration: during the bounded migration period, a v2 installation
- * marker also accepts v1 skills if the v2 skill is not yet installed. This
- * prevents old snapshots from being rejected while the learner upgrades.
- */
-const LEGACY_CONTRACT_ALIASES: Readonly<Record<string, string>> = {
-  'teach-quick-v2': 'teach-quick-v1',
-  'teach-ria-v2': 'teach-ria-v1',
+/** Bounded migration aliases: newer Skills can resume old pinned courses.
+ * Current v4 profiles require the exact v4 marker so quality and revision gates cannot be
+ * silently downgraded by an older installation. */
+const COMPATIBLE_CONTRACT_ALIASES: Readonly<Record<string, readonly string[]>> = {
+  'teach-quick-v1': ['teach-quick-v2', 'teach-quick-v3', 'teach-quick-v4'],
+  'teach-quick-v2': ['teach-quick-v1', 'teach-quick-v3', 'teach-quick-v4'],
+  'teach-quick-v3': ['teach-quick-v4'],
+  'teach-ria-v1': ['teach-ria-v2', 'teach-ria-v3', 'teach-ria-v4'],
+  'teach-ria-v2': ['teach-ria-v1', 'teach-ria-v3', 'teach-ria-v4'],
+  'teach-ria-v3': ['teach-ria-v4'],
 };
 
 export function installedSkillMatches(
@@ -111,10 +124,9 @@ export function installedSkillMatches(
   if (installed.name !== expected.name) return false;
   const expectedMarker = `[contract:${expected.contractRevision}]`;
   if (installed.description.includes(expectedMarker)) return true;
-  // Accept v1 skill when v2 is expected, for bounded migration.
-  const legacyRevision = LEGACY_CONTRACT_ALIASES[expected.contractRevision];
-  return legacyRevision !== undefined
-    && installed.description.includes(`[contract:${legacyRevision}]`);
+  const aliases = COMPATIBLE_CONTRACT_ALIASES[expected.contractRevision] ?? [];
+  return aliases.some((revision) =>
+    installed.description.includes(`[contract:${revision}]`));
 }
 
 export class KimiStudyRuntime implements StudyRuntimePort {
@@ -287,7 +299,7 @@ export class KimiStudyRuntime implements StudyRuntimePort {
     connection = this.api.connectEvents({
       onEvent: (event) => this.handleEvent(event, binding.sessionId, handlers),
       onResync: (sessionId) => {
-        if (sessionId === binding.sessionId) handlers.onArtifactChanged();
+        if (sessionId === binding.sessionId) handlers.onArtifactChanged('resync');
       },
       onError: (_code, message, fatal) => {
         if (fatal) handlers.onPolicyViolation(message);
@@ -390,6 +402,40 @@ export class KimiStudyRuntime implements StudyRuntimePort {
     });
   }
 
+  async requestLessonChange(
+    courseId: string,
+    lessonPath: string,
+    baseRevision: string,
+    instruction: string,
+    operationId: string,
+  ): Promise<void> {
+    const text = instruction.trim();
+    if (text.length === 0) throw new Error('Lesson change request is empty.');
+    await this.submitLessonOperation(
+      courseId,
+      lessonPath,
+      baseRevision,
+      operationId,
+      'revise',
+      text,
+    );
+  }
+
+  async requestLessonRegeneration(
+    courseId: string,
+    lessonPath: string,
+    baseRevision: string,
+    operationId: string,
+  ): Promise<void> {
+    await this.submitLessonOperation(
+      courseId,
+      lessonPath,
+      baseRevision,
+      operationId,
+      'regenerate',
+    );
+  }
+
   async readCourseText(courseId: string, path: string, maxBytes = 262144): Promise<StudyTextLoad> {
     assertArtifactPath(path);
     const binding = await this.resumeCourse(courseId);
@@ -481,6 +527,61 @@ export class KimiStudyRuntime implements StudyRuntimePort {
     return materials;
   }
 
+  private async submitLessonOperation(
+    courseId: string,
+    lessonPath: string,
+    baseRevision: string,
+    operationId: string,
+    kind: 'revise' | 'regenerate',
+    instruction?: string,
+  ): Promise<void> {
+    assertCourseId(courseId);
+    assertLessonOperation(lessonPath, baseRevision, operationId);
+    const binding = this.requireBinding(courseId);
+    const operation = `${courseId}:lesson-${kind}:${operationId}`;
+    await this.coalesce(operation, async () => {
+      if (binding.operations[operation] !== undefined
+        || await this.sessionHasOperation(binding.sessionId, operation)) return;
+      const action = kind === 'revise'
+        ? `Revise only the published lesson ${lessonPath} from the learner request: ${instruction ?? ''}`
+        : `Regenerate only the published lesson ${lessonPath}.`;
+      const submitted = await this.api.submitPrompt(binding.sessionId, {
+        content: [{
+          type: 'text',
+          text: [
+            action,
+            `Its required base content revision is ${baseRevision}.`,
+            'Keep the course id, lesson path, lesson title, source anchors, plan, generation counts, and every other lesson unchanged.',
+            'Follow the installed Skill lesson-revision workflow: reopen the cited source, validate a candidate, then use the guarded atomic publisher immediately before replacement.',
+            'If the base revision is stale or any gate fails, do not replace the current lesson.',
+          ].join(' '),
+        }],
+        metadata: {
+          kimiStudyOperationId: operation,
+          kimiStudyCourseId: courseId,
+          kimiStudyLessonOperation: kind,
+          kimiStudyLessonPath: lessonPath,
+          kimiStudyLessonBaseRevision: baseRevision,
+        },
+        permissionMode: 'auto',
+        planMode: false,
+        swarmMode: false,
+      });
+      this.registry.saveCourse({
+        ...binding,
+        operations: {
+          ...binding.operations,
+          [operation]: {
+            operationId: operation,
+            promptId: submitted.promptId,
+            startedAt: this.now(),
+          },
+        },
+        updatedAt: this.now(),
+      });
+    });
+  }
+
   private async ensureBinding(
     snapshot: CourseSnapshot,
     uploadedMaterial?: UploadedMaterial,
@@ -693,7 +794,7 @@ export class KimiStudyRuntime implements StudyRuntimePort {
       handlers.onQuestionClosed(event.questionId);
     }
     if (event.type === 'sessionStatusChanged' && event.status === 'idle') {
-      handlers.onArtifactChanged();
+      handlers.onArtifactChanged('session_idle');
     }
     if (event.type === 'approvalRequested') {
       handlers.onPolicyViolation('A developer approval escaped automatic Study policy.');
diff --git a/apps/kimi-web/src/study/runtime/studyRuntime.ts b/apps/kimi-web/src/study/runtime/studyRuntime.ts
index a799cdfa..9485ee86 100644
--- a/apps/kimi-web/src/study/runtime/studyRuntime.ts
+++ b/apps/kimi-web/src/study/runtime/studyRuntime.ts
@@ -45,7 +45,7 @@ export type StudyQuestion = AppQuestionRequest & {
 export interface StudyRuntimeWatchHandlers {
   readonly onQuestion: (question: StudyQuestion) => void;
   readonly onQuestionClosed: (questionId: string) => void;
-  readonly onArtifactChanged: () => void;
+  readonly onArtifactChanged: (reason: 'session_idle' | 'resync') => void;
   readonly onConnectionChange: (connected: boolean) => void;
   readonly onPolicyViolation: (message: string) => void;
 }
@@ -80,6 +80,21 @@ export interface StudyRuntimePort {
   listTutorMessages(courseId: string): Promise<readonly AppMessage[]>;
   /** Request a new plan revision from learner feedback on the visible revision. */
   requestPlanChange(courseId: string, planRevision: string, instruction: string): Promise<void>;
+  /** Revise exactly one published lesson from its current content identity. */
+  requestLessonChange(
+    courseId: string,
+    lessonPath: string,
+    baseRevision: string,
+    instruction: string,
+    operationId: string,
+  ): Promise<void>;
+  /** Regenerate exactly one published lesson from its current content identity. */
+  requestLessonRegeneration(
+    courseId: string,
+    lessonPath: string,
+    baseRevision: string,
+    operationId: string,
+  ): Promise<void>;
 }
 
 export function normalizeStudyQuestion(
diff --git a/apps/kimi-web/study-evals/README.md b/apps/kimi-web/study-evals/README.md
new file mode 100644
index 00000000..a390ab8e
--- /dev/null
+++ b/apps/kimi-web/study-evals/README.md
@@ -0,0 +1,52 @@
+# Kimi Study Chinese course quality evals
+
+This directory is a small, reproducible quality gate for Kimi Study Core v1.
+It is intentionally not a benchmark platform and does not claim superiority
+over Coursebox or any other product.
+
+## What is included
+
+`fixtures/` contains five original synthetic Chinese sources that are safe to
+redistribute:
+
+- product instructions;
+- a nonfiction article;
+- a technical guide;
+- a policy notice;
+- training material.
+
+Each fixture contains:
+
+- `source.md`: the uploaded-material proxy with stable anchors;
+- `expected.json`: allowed anchors, required source facts, objective keywords,
+  and a deliberately unsupported claim;
+- `plan.json`: a short source-to-outline disposition;
+- `lesson.html`: one incrementally generated reference lesson.
+
+The reference lessons were authored from only their checked-in synthetic
+sources. They are regression evidence for the v3 contract, not measurements of
+a live provider or representative production quality.
+
+## Run
+
+```bash
+python apps/kimi-web/study-evals/evaluate_lessons.py
+python -m pytest -q apps/kimi-web/study-evals
+```
+
+The evaluator uses the same deterministic lesson-quality module bundled in the
+Quick and Deep Skills. It checks all nine rubric dimensions where an offline
+proxy is possible: outline anchor coverage, section progression, source-fact
+coverage, evidence labels, Chinese structure, examples, repetition, self-check
+alignment, and unsupported claims.
+
+Semantic truth still requires source rereading. The Skill contracts explicitly
+retain that human/model comparison before publication; this evaluator catches
+missing or invented fixture anchors but cannot prove arbitrary prose true.
+
+## Adding a fixture
+
+Use only original, public-domain, or explicitly redistributable text. Add stable
+anchors, declare every anchor in `expected.json`, and include at least one
+forbidden claim that a weak generator might invent. Never commit private
+documents, complete copyrighted books, credentials, or real personal data.
diff --git a/apps/kimi-web/study-evals/evaluate_lessons.py b/apps/kimi-web/study-evals/evaluate_lessons.py
new file mode 100644
index 00000000..e257cab9
--- /dev/null
+++ b/apps/kimi-web/study-evals/evaluate_lessons.py
@@ -0,0 +1,222 @@
+#!/usr/bin/env python3
+"""Run the small deterministic Kimi Study Chinese lesson quality evaluation."""
+
+from __future__ import annotations
+
+import argparse
+import json
+import sys
+from pathlib import Path
+from typing import Any
+
+
+ROOT = Path(__file__).resolve().parent
+QUALITY_MODULE_DIR = ROOT.parent / "study-skills" / "teach-quick" / "scripts"
+sys.path.insert(0, str(QUALITY_MODULE_DIR))
+from lesson_quality import find_repeated_blocks, inspect_lesson_html, validate_lesson_html
+
+
+EXPECTED_CATEGORIES = {
+    "产品说明",
+    "非虚构文章",
+    "技术指南",
+    "政策说明",
+    "培训材料",
+}
+
+
+def _read_json(path: Path) -> dict[str, Any]:
+    value = json.loads(path.read_text(encoding="utf-8"))
+    if not isinstance(value, dict):
+        raise ValueError(f"{path}: JSON root must be an object")
+    return value
+
+
+def _validate_plan(plan: dict[str, Any], coverage_anchors: set[str], label: str) -> tuple[list[str], int]:
+    errors: list[str] = []
+    if plan.get("schemaVersion") != 1:
+        errors.append(f"{label}: unsupported plan schema")
+    lessons = plan.get("lessons")
+    deferrals = plan.get("visibleDeferrals", [])
+    if not isinstance(lessons, list) or len(lessons) < 2:
+        return errors + [f"{label}: plan needs at least two progressive lessons"], 0
+    if not isinstance(deferrals, list):
+        return errors + [f"{label}: visibleDeferrals must be an array"], 0
+
+    covered: set[str] = set()
+    seen_titles: set[str] = set()
+    for index, lesson in enumerate(lessons, start=1):
+        if not isinstance(lesson, dict):
+            errors.append(f"{label}: lesson {index} must be an object")
+            continue
+        if lesson.get("order") != index:
+            errors.append(f"{label}: lesson order must be contiguous")
+        title = str(lesson.get("title", "")).strip()
+        objective = str(lesson.get("objective", "")).strip()
+        anchors = lesson.get("sourceAnchors")
+        if not title or title in seen_titles:
+            errors.append(f"{label}: lesson {index} has a missing or duplicate title")
+        seen_titles.add(title)
+        if len(objective) < 12:
+            errors.append(f"{label}: lesson {index} objective is not observable")
+        if not isinstance(anchors, list) or not all(isinstance(anchor, str) for anchor in anchors):
+            errors.append(f"{label}: lesson {index} sourceAnchors are invalid")
+        else:
+            covered.update(anchors)
+
+    for item in deferrals:
+        if not isinstance(item, dict) or not str(item.get("reason", "")).strip():
+            errors.append(f"{label}: every deferral needs a visible reason")
+            continue
+        anchors = item.get("sourceAnchors", [])
+        if isinstance(anchors, list):
+            covered.update(anchor for anchor in anchors if isinstance(anchor, str))
+
+    missing = coverage_anchors - covered
+    if missing:
+        errors.append(f"{label}: outline omits source anchor {sorted(missing)[0]}")
+    unknown = covered - coverage_anchors
+    if unknown:
+        errors.append(f"{label}: outline invents source anchor {sorted(unknown)[0]}")
+    return errors, len(coverage_anchors & covered)
+
+
+def evaluate(fixtures_root: Path = ROOT / "fixtures") -> dict[str, Any]:
+    results: list[dict[str, Any]] = []
+    lesson_documents: dict[str, str] = {}
+    categories: set[str] = set()
+    total_outline_anchors = 0
+    covered_outline_anchors = 0
+    total_required_facts = 0
+    covered_required_facts = 0
+    invalid_anchors = 0
+    forbidden_claims = 0
+
+    for fixture_dir in sorted(path for path in fixtures_root.iterdir() if path.is_dir()):
+        errors: list[str] = []
+        try:
+            expected = _read_json(fixture_dir / "expected.json")
+            plan = _read_json(fixture_dir / "plan.json")
+            source = (fixture_dir / "source.md").read_text(encoding="utf-8")
+            lesson_path = fixture_dir / str(expected.get("lessonPath", "lesson.html"))
+            lesson = lesson_path.read_text(encoding="utf-8")
+        except (OSError, UnicodeDecodeError, json.JSONDecodeError, ValueError) as error:
+            results.append({
+                "id": fixture_dir.name,
+                "category": "unknown",
+                "passed": False,
+                "errors": [str(error)],
+            })
+            continue
+
+        fixture_id = str(expected.get("id", fixture_dir.name))
+        category = str(expected.get("category", ""))
+        categories.add(category)
+        if expected.get("schemaVersion") != 1:
+            errors.append("expected.json: unsupported schema")
+        if fixture_id != fixture_dir.name:
+            errors.append("expected.json: id must match fixture directory")
+
+        coverage_anchors = set(expected.get("coverageAnchors", []))
+        if not coverage_anchors or not all(isinstance(anchor, str) for anchor in coverage_anchors):
+            errors.append("expected.json: coverageAnchors are missing")
+            coverage_anchors = set()
+        for anchor in coverage_anchors:
+            if anchor not in source:
+                errors.append(f"source.md: declared anchor is absent: {anchor}")
+
+        plan_errors, covered = _validate_plan(plan, coverage_anchors, "plan.json")
+        errors.extend(plan_errors)
+        total_outline_anchors += len(coverage_anchors)
+        covered_outline_anchors += covered
+
+        errors.extend(validate_lesson_html(lesson, "lesson.html"))
+        report = inspect_lesson_html(lesson)
+        lesson_documents[fixture_id] = lesson
+        used_anchors = set(report["anchors"])
+        allowed_anchors = set(expected.get("allowedLessonAnchors", []))
+        unknown_anchors = used_anchors - allowed_anchors
+        invalid_anchors += len(unknown_anchors)
+        for anchor in sorted(unknown_anchors):
+            errors.append(f"lesson.html: invented or disallowed source anchor {anchor}")
+
+        source_evidence = " ".join(
+            str(item.get("text", "")) for item in report["sourceEvidence"]
+        )
+        required_facts = expected.get("requiredSourcePhrases", [])
+        total_required_facts += len(required_facts)
+        for fact in required_facts:
+            if not isinstance(fact, str) or fact not in source:
+                errors.append(f"expected source fact is absent from source.md: {fact}")
+            elif fact not in source_evidence:
+                errors.append(f"lesson source evidence omits required fact: {fact}")
+            else:
+                covered_required_facts += 1
+
+        sections = report["sections"]
+        objective = str(sections.get("learning-objective", ""))
+        self_check = str(sections.get("self-check", ""))
+        for keyword in expected.get("objectiveKeywords", []):
+            if keyword not in objective or keyword not in self_check:
+                errors.append(f"self-check is not aligned to objective keyword: {keyword}")
+
+        visible = str(report["visibleText"])
+        for claim in expected.get("forbiddenClaims", []):
+            if isinstance(claim, str) and claim in visible:
+                forbidden_claims += 1
+                errors.append(f"lesson contains unsupported claim: {claim}")
+
+        results.append({
+            "id": fixture_id,
+            "category": category,
+            "passed": not errors,
+            "generatedLessons": 1,
+            "outlineAnchors": len(coverage_anchors),
+            "requiredSourceFacts": len(required_facts),
+            "errors": errors,
+        })
+
+    global_errors = [
+        f"missing required fixture category: {category}"
+        for category in sorted(EXPECTED_CATEGORIES - categories)
+    ]
+    global_errors.extend(
+        f"cross-fixture repetition: {error}"
+        for error in find_repeated_blocks(lesson_documents)
+    )
+    passed = sum(1 for result in results if result["passed"])
+    return {
+        "schemaVersion": 1,
+        "method": "offline synthetic fixtures; deterministic structural and grounding proxy",
+        "fixtureCount": len(results),
+        "passedFixtures": passed if not global_errors else 0,
+        "categories": sorted(categories),
+        "metrics": {
+            "outlineAnchorCoverage": {
+                "covered": covered_outline_anchors,
+                "total": total_outline_anchors,
+            },
+            "requiredSourceFactCoverage": {
+                "covered": covered_required_facts,
+                "total": total_required_facts,
+            },
+            "invalidSourceAnchors": invalid_anchors,
+            "unsupportedForbiddenClaims": forbidden_claims,
+            "repeatedBlocks": len(global_errors) - len(EXPECTED_CATEGORIES - categories),
+        },
+        "globalErrors": global_errors,
+        "results": results,
+    }
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--fixtures", type=Path, default=ROOT / "fixtures")
+    args = parser.parse_args()
+    report = evaluate(args.fixtures.expanduser().resolve())
+    print(json.dumps(report, ensure_ascii=False, indent=2))
+    return 0 if report["passedFixtures"] == len(EXPECTED_CATEGORIES) else 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/apps/kimi-web/study-evals/fixtures/nonfiction-article/expected.json b/apps/kimi-web/study-evals/fixtures/nonfiction-article/expected.json
new file mode 100644
index 00000000..83cb161c
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/nonfiction-article/expected.json
@@ -0,0 +1,14 @@
+{
+  "schemaVersion": 1,
+  "id": "nonfiction-article",
+  "category": "非虚构文章",
+  "lessonPath": "lesson.html",
+  "coverageAnchors": ["A-1 到馆记录", "A-2 同期变化", "A-3 访谈线索"],
+  "allowedLessonAnchors": ["A-1 到馆记录", "A-2 同期变化"],
+  "requiredSourcePhrases": [
+    "日均到馆人数从 420 人增至 510 人",
+    "新公交线路开始运营"
+  ],
+  "objectiveKeywords": ["因果", "证据"],
+  "forbiddenClaims": ["图书馆改造使日均到馆人数增加了 90 人"]
+}
diff --git a/apps/kimi-web/study-evals/fixtures/nonfiction-article/lesson.html b/apps/kimi-web/study-evals/fixtures/nonfiction-article/lesson.html
new file mode 100644
index 00000000..51932f1d
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/nonfiction-article/lesson.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="zh-CN"><body>
+<h1>数字上升，不等于原因已经确定</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能把文章中的观察证据与因果解释分开，并指出还需要排除哪些同期变化才能支持因果判断。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>“改造后人数上升”描述时间上的共同变化；“改造导致人数上升”则排除了其他解释。后一句需要比前一句更多证据。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>先问数字记录了什么，再问同一时期还有什么发生。如果多个条件一起变化，单凭前后对比只能确认结果变了，不能确认是哪一个条件造成变化。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="A-1 到馆记录">文章记录：改造后的前三个月，日均到馆人数从 420 人增至 510 人；这是观察到的增长，不是单独原因的证明。</p><p data-evidence="source" data-source-anchor="A-2 同期变化">文章同时说明新公交线路开始运营，闭馆时间也延长到 20:00，而且现有记录没有分离这些影响。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：一家咖啡店换招牌后客流增加，但同周办公楼入住。你可以报告客流变化，却不能只凭时间先后断定招牌是原因。该情境不是文章中的案例。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>把“存在其他因素”说成“改造肯定无效”同样越界。材料支持的是因果贡献尚未被单独识别，而不是改造完全没有作用。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>先写观察事实，再列同期变化，最后说明当前证据能否排除替代解释；无法排除时，把结论停在相关变化而不是因果断言。</p></section>
+<section id="self-check"><h2>自测题</h2><p>现有证据能否支持“改造导致人数增加”的因果判断？不能。合格回答要引用人数变化，并指出公交和延时开放尚未被分离。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>A-1 到馆记录：日均人数与借阅变化；A-2 同期变化：公交、开放时间及文章明确写出的识别限制。</p></section>
+</body></html>
diff --git a/apps/kimi-web/study-evals/fixtures/nonfiction-article/plan.json b/apps/kimi-web/study-evals/fixtures/nonfiction-article/plan.json
new file mode 100644
index 00000000..4f5f543c
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/nonfiction-article/plan.json
@@ -0,0 +1,19 @@
+{
+  "schemaVersion": 1,
+  "title": "从增长数字读到因果边界",
+  "lessons": [
+    {
+      "order": 1,
+      "title": "区分观察到的变化与因果结论",
+      "objective": "从同一组数字中分别写出观察事实和仍待验证的因果解释",
+      "sourceAnchors": ["A-1 到馆记录", "A-2 同期变化"]
+    },
+    {
+      "order": 2,
+      "title": "判断访谈能支持到哪一步",
+      "objective": "根据抽样时间与人数说明访谈线索可以提示什么、不能代表什么",
+      "sourceAnchors": ["A-3 访谈线索"]
+    }
+  ],
+  "visibleDeferrals": []
+}
diff --git a/apps/kimi-web/study-evals/fixtures/nonfiction-article/source.md b/apps/kimi-web/study-evals/fixtures/nonfiction-article/source.md
new file mode 100644
index 00000000..5a55bb0e
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/nonfiction-article/source.md
@@ -0,0 +1,15 @@
+# 社区图书馆改造之后（合成文章）
+
+本文章为 Kimi Study 质量评估原创合成文本，数据只服务于因果阅读练习。
+
+## A-1 到馆记录
+
+改造后的前三个月，日均到馆人数从 420 人增至 510 人。同期借阅册数从日均 265 册增至 292 册，但周末增幅明显高于工作日。
+
+## A-2 同期变化
+
+同期，连接社区与地铁站的新公交线路开始运营。图书馆还将闭馆时间从 18:00 延长至 20:00。现有记录没有把公交与延时开放的影响单独分离出来。
+
+## A-3 访谈线索
+
+二十名受访者中，九人提到儿童区座位增加，六人提到晚间开放，五人提到新的公交站。访谈样本来自连续两个周六，不能代表全部居民。
diff --git a/apps/kimi-web/study-evals/fixtures/policy-notice/expected.json b/apps/kimi-web/study-evals/fixtures/policy-notice/expected.json
new file mode 100644
index 00000000..9bcf02ae
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/policy-notice/expected.json
@@ -0,0 +1,14 @@
+{
+  "schemaVersion": 1,
+  "id": "policy-notice",
+  "category": "政策说明",
+  "lessonPath": "lesson.html",
+  "coverageAnchors": ["POL-1 申请资格", "POL-2 申请期限", "POL-3 材料保存"],
+  "allowedLessonAnchors": ["POL-1 申请资格", "POL-2 申请期限"],
+  "requiredSourcePhrases": [
+    "连续缴纳社会保险满 12 个月",
+    "申请窗口为 2026 年 6 月 1 日至 6 月 30 日"
+  ],
+  "objectiveKeywords": ["资格", "期限"],
+  "forbiddenClaims": ["符合条件的家庭会自动获得补贴"]
+}
diff --git a/apps/kimi-web/study-evals/fixtures/policy-notice/lesson.html b/apps/kimi-web/study-evals/fixtures/policy-notice/lesson.html
new file mode 100644
index 00000000..aa9d1530
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/policy-notice/lesson.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="zh-CN"><body>
+<h1>先核对资格，再守住申请期限</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能同时核对申请资格与申请期限，并指出条件缺失或时间逾期时应得到什么结论。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>政策判断需要把“谁可以申请”和“何时可以申请”分开核对。满足身份条件并不等于已经提交，也不等于系统自动发放。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>先做资格检查：社保月份和子女入托时间必须同时满足；再做时间检查：首次申请必须落在六月窗口内。任何一关不通过，都不能写成当前批次可申请。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="POL-1 申请资格">说明要求申请人在本市连续缴纳社会保险满 12 个月，且子女于 2026 年 9 月进入公办托育机构，两项条件同时满足。</p><p data-evidence="source" data-source-anchor="POL-2 申请期限">说明写明申请窗口为 2026 年 6 月 1 日至 6 月 30 日，逾期申请转入下一年度批次。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：一名监护人社保已满 12 个月，子女符合入托时间，但在 7 月 2 日才首次提交。该情境用于练习，结论应是转入下一年度批次。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>把“符合资格”解释成“自动获得补贴”忽略了申请动作、审核过程和时间窗口。材料没有授权这样的自动发放结论。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>先检查社保与入托两项资格，再检查六月申请窗口；资格成立但逾期时，不是资格消失，而是进入下一年度批次。</p></section>
+<section id="self-check"><h2>自测题</h2><p>申请人资格都满足，但 7 月首次提交，能否进入 2026 年批次？不能。答案应引用申请期限为 6 月 30 日，并说明转入下一年度。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>POL-1 申请资格：社保与入托条件；POL-2 申请期限：首次申请窗口、逾期处理和补正时限。</p></section>
+</body></html>
diff --git a/apps/kimi-web/study-evals/fixtures/policy-notice/plan.json b/apps/kimi-web/study-evals/fixtures/policy-notice/plan.json
new file mode 100644
index 00000000..95c06323
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/policy-notice/plan.json
@@ -0,0 +1,25 @@
+{
+  "schemaVersion": 1,
+  "title": "按条件和时间完成补贴申请",
+  "lessons": [
+    {
+      "order": 1,
+      "title": "同时核对两项申请资格",
+      "objective": "根据社保期限和入托时间判断家庭是否满足申请资格",
+      "sourceAnchors": ["POL-1 申请资格"]
+    },
+    {
+      "order": 2,
+      "title": "区分申请窗口与补正期限",
+      "objective": "为首次申请和收到补正通知两种情况分别计算截止时间",
+      "sourceAnchors": ["POL-2 申请期限"]
+    },
+    {
+      "order": 3,
+      "title": "理解审核结果对应的保存期限",
+      "objective": "说明通过与未通过材料的不同保存和删除规则",
+      "sourceAnchors": ["POL-3 材料保存"]
+    }
+  ],
+  "visibleDeferrals": []
+}
diff --git a/apps/kimi-web/study-evals/fixtures/policy-notice/source.md b/apps/kimi-web/study-evals/fixtures/policy-notice/source.md
new file mode 100644
index 00000000..e5cf3dfc
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/policy-notice/source.md
@@ -0,0 +1,15 @@
+# 2026 年公办托育补贴申请说明（合成政策）
+
+本说明为 Kimi Study 质量评估原创合成文本，不代表任何真实政府政策。
+
+## POL-1 申请资格
+
+申请人须在本市连续缴纳社会保险满 12 个月，且子女于 2026 年 9 月进入公办托育机构。两项条件必须同时满足。每个家庭只能由一名监护人提交申请。
+
+## POL-2 申请期限
+
+申请窗口为 2026 年 6 月 1 日至 6 月 30 日，逾期转入下一年度批次。材料补正通知发出后，申请人有 5 个工作日完成补交。
+
+## POL-3 材料保存
+
+通过审核的申请材料保存至补贴发放结束后两年。未通过审核的材料在结果通知后 30 日删除。统计报表只保留去标识化汇总数据。
diff --git a/apps/kimi-web/study-evals/fixtures/product-instructions/expected.json b/apps/kimi-web/study-evals/fixtures/product-instructions/expected.json
new file mode 100644
index 00000000..f3e88a68
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/product-instructions/expected.json
@@ -0,0 +1,14 @@
+{
+  "schemaVersion": 1,
+  "id": "product-instructions",
+  "category": "产品说明",
+  "lessonPath": "lesson.html",
+  "coverageAnchors": ["P-1 安装条件", "P-2 指示灯状态", "P-3 复位与记录"],
+  "allowedLessonAnchors": ["P-2 指示灯状态", "P-3 复位与记录"],
+  "requiredSourcePhrases": [
+    "蓝灯慢闪表示等待配对",
+    "长按复位键 8 秒会清除配对记录"
+  ],
+  "objectiveKeywords": ["指示灯", "判断"],
+  "forbiddenClaims": ["设备支持 5GHz Wi-Fi"]
+}
diff --git a/apps/kimi-web/study-evals/fixtures/product-instructions/lesson.html b/apps/kimi-web/study-evals/fixtures/product-instructions/lesson.html
new file mode 100644
index 00000000..134bb99a
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/product-instructions/lesson.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="zh-CN"><body>
+<h1>先读灯光，再处理设备</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能根据指示灯判断设备处于等待配对、已经连接还是低电量，并选择材料允许的处理动作。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>指示灯不是装饰，而是一组状态编码。判断时要把灯光的颜色、闪烁方式和对应动作一起读取，不能只看颜色。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>先完整描述“什么颜色、怎样闪”，再查状态，最后行动。比如蓝灯慢闪和绿灯常亮虽然都不是故障，但一个要求配对，另一个表示无需重复配对。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="P-2 指示灯状态">材料中说明：蓝灯慢闪表示等待配对；红灯连续闪烁三次表示电池电量低于 15%，应在 24 小时内更换电池。</p><p data-evidence="source" data-source-anchor="P-3 复位与记录">材料中说明：长按复位键 8 秒会清除配对记录，但不会删除最近 24 小时的本地温湿度记录。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：同事看到蓝灯便准备换电池，你先补问“是慢闪还是连续三闪”，再据此纠正动作。这个同事情境用于练习，并非产品说明中的真实事件。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>把复位理解成“恢复出厂并删除全部数据”会扩大材料中的结论。说明书只明确清除配对记录，同时明确保留最近 24 小时测量记录。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>判断顺序是：完整观察灯光模式，匹配材料中的状态，再执行配对、保持连接或更换电池；复位前另行核对它会影响哪些记录。</p></section>
+<section id="self-check"><h2>自测题</h2><p>设备指示灯蓝色慢闪时应如何判断？答案应指出它正在等待配对，而不是低电量；若回答只写“蓝灯正常”，说明没有使用闪烁方式这一关键信号。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>P-2 指示灯状态：三种灯光模式及动作；P-3 复位与记录：复位时清除配对记录、保留本地测量记录的边界。</p></section>
+</body></html>
diff --git a/apps/kimi-web/study-evals/fixtures/product-instructions/plan.json b/apps/kimi-web/study-evals/fixtures/product-instructions/plan.json
new file mode 100644
index 00000000..334916b8
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/product-instructions/plan.json
@@ -0,0 +1,25 @@
+{
+  "schemaVersion": 1,
+  "title": "从状态判断到安全复位",
+  "lessons": [
+    {
+      "order": 1,
+      "title": "用指示灯判断设备状态",
+      "objective": "根据三种灯光信号判断设备当前状态并选择下一步动作",
+      "sourceAnchors": ["P-2 指示灯状态"]
+    },
+    {
+      "order": 2,
+      "title": "在合适环境中安装设备",
+      "objective": "检查距离、蓝牙和安装环境是否满足首次安装条件",
+      "sourceAnchors": ["P-1 安装条件"]
+    },
+    {
+      "order": 3,
+      "title": "区分复位会清除和保留的内容",
+      "objective": "执行复位前说明配对记录与本地测量记录的不同结果",
+      "sourceAnchors": ["P-3 复位与记录"]
+    }
+  ],
+  "visibleDeferrals": []
+}
diff --git a/apps/kimi-web/study-evals/fixtures/product-instructions/source.md b/apps/kimi-web/study-evals/fixtures/product-instructions/source.md
new file mode 100644
index 00000000..7f7df607
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/product-instructions/source.md
@@ -0,0 +1,15 @@
+# 芯连温湿度传感器使用说明（合成资料）
+
+本资料为 Kimi Study 质量评估原创合成文本，可再分发，不对应真实产品。
+
+## P-1 安装条件
+
+设备仅用于室内。首次安装前，手机需要开启蓝牙，并与设备保持在三米以内。安装位置应避开冷凝水和连续直射阳光。
+
+## P-2 指示灯状态
+
+蓝灯慢闪表示等待配对。绿灯常亮表示连接已经建立。红灯连续闪烁三次表示电池电量低于 15%，此时应在 24 小时内更换电池。
+
+## P-3 复位与记录
+
+长按复位键 8 秒会清除配对记录。复位不会删除设备本地保存的最近 24 小时温湿度记录。复位后蓝灯恢复慢闪，用户需要重新完成配对。
diff --git a/apps/kimi-web/study-evals/fixtures/technical-guide/expected.json b/apps/kimi-web/study-evals/fixtures/technical-guide/expected.json
new file mode 100644
index 00000000..ad9112cd
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/technical-guide/expected.json
@@ -0,0 +1,14 @@
+{
+  "schemaVersion": 1,
+  "id": "technical-guide",
+  "category": "技术指南",
+  "lessonPath": "lesson.html",
+  "coverageAnchors": ["T-1 重试预算", "T-2 幂等键", "T-3 不可重试响应"],
+  "allowedLessonAnchors": ["T-1 重试预算", "T-3 不可重试响应"],
+  "requiredSourcePhrases": [
+    "客户端最多重试 3 次",
+    "400 和 401 响应不得自动重试"
+  ],
+  "objectiveKeywords": ["重试", "判断"],
+  "forbiddenClaims": ["所有 5xx 响应都必须无限重试"]
+}
diff --git a/apps/kimi-web/study-evals/fixtures/technical-guide/lesson.html b/apps/kimi-web/study-evals/fixtures/technical-guide/lesson.html
new file mode 100644
index 00000000..ec0020a8
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/technical-guide/lesson.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="zh-CN"><body>
+<h1>重试之前，先判断错误是否会自行消失</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能根据响应类型判断是否允许自动重试，并在预算内给出下一次等待时间。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>重试只适合暂时性失败。若请求本身错误或凭据失效，重复发送不会修复原因，反而会放大流量和故障。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>把错误先分成“稍后可能恢复”和“必须修改输入或身份”两类。前一类才进入次数与间隔控制，后一类应立即返回给调用方处理。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="T-1 重试预算">指南规定只对 429 和 503 自动重试；客户端最多重试 3 次，等待 1 秒、2 秒和 4 秒，并加入随机抖动。</p><p data-evidence="source" data-source-anchor="T-3 不可重试响应">指南明确写明：400 和 401 响应不得自动重试，前者需要修正请求，后者需要更新凭据。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：服务返回 503 后，客户端等待约 1 秒再试；若随后返回 400，就停止并提示检查字段。这个响应序列用于练习，并非指南记录的事故。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>“服务器错误都可以重试”把范围扩大了。材料只授权 429 和 503；没有列出的状态不能靠模型常识补进允许清单。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>先按状态判断可重试性，再应用三次预算、递增等待和抖动；遇到 400 或 401 时停止重试，转向修正请求或凭据。</p></section>
+<section id="self-check"><h2>自测题</h2><p>请判断第二次 503 后应怎样处理：可以在预算内等待约 2 秒并加入抖动后重试；若状态变成 401，则应停止并更新凭据。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>T-1 重试预算：允许状态、次数、间隔与抖动；T-3 不可重试响应：400、401 的停止条件和修复方向。</p></section>
+</body></html>
diff --git a/apps/kimi-web/study-evals/fixtures/technical-guide/plan.json b/apps/kimi-web/study-evals/fixtures/technical-guide/plan.json
new file mode 100644
index 00000000..14154d34
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/technical-guide/plan.json
@@ -0,0 +1,19 @@
+{
+  "schemaVersion": 1,
+  "title": "让重试安全而有边界",
+  "lessons": [
+    {
+      "order": 1,
+      "title": "先判断响应，再消耗重试预算",
+      "objective": "根据响应类型决定是否重试，并计算下一次等待时间",
+      "sourceAnchors": ["T-1 重试预算", "T-3 不可重试响应"]
+    },
+    {
+      "order": 2,
+      "title": "用幂等键避免重复订单",
+      "objective": "为内容相同与内容变化的创建请求选择正确的幂等键",
+      "sourceAnchors": ["T-2 幂等键"]
+    }
+  ],
+  "visibleDeferrals": []
+}
diff --git a/apps/kimi-web/study-evals/fixtures/technical-guide/source.md b/apps/kimi-web/study-evals/fixtures/technical-guide/source.md
new file mode 100644
index 00000000..4e0d364d
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/technical-guide/source.md
@@ -0,0 +1,15 @@
+# 订单接口重试指南（合成资料）
+
+本指南为 Kimi Study 质量评估原创合成文本，不对应任何生产接口。
+
+## T-1 重试预算
+
+客户端只可对 429 和 503 响应自动重试。客户端最多重试 3 次，等待间隔依次为 1 秒、2 秒和 4 秒。每次等待还应加入 0 至 300 毫秒随机抖动。
+
+## T-2 幂等键
+
+创建订单请求必须携带由客户端生成的幂等键。相同幂等键在 24 小时内返回第一次成功请求的结果。更换请求内容时必须使用新键。
+
+## T-3 不可重试响应
+
+400 和 401 响应不得自动重试。400 表示请求结构需要修正；401 表示调用方需要重新取得有效凭据。网络连接在发送前失败时不计入服务端重试预算。
diff --git a/apps/kimi-web/study-evals/fixtures/training-material/expected.json b/apps/kimi-web/study-evals/fixtures/training-material/expected.json
new file mode 100644
index 00000000..2756a4a5
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/training-material/expected.json
@@ -0,0 +1,14 @@
+{
+  "schemaVersion": 1,
+  "id": "training-material",
+  "category": "培训材料",
+  "lessonPath": "lesson.html",
+  "coverageAnchors": ["TR-1 班前检查", "TR-2 行人与盲区", "TR-3 事故处置"],
+  "allowedLessonAnchors": ["TR-1 班前检查", "TR-2 行人与盲区"],
+  "requiredSourcePhrases": [
+    "发现液压油渗漏时不得启动车辆",
+    "驾驶员须减速、鸣笛，并让行人先行"
+  ],
+  "objectiveKeywords": ["检查", "停机"],
+  "forbiddenClaims": ["少量渗漏可以完成本班作业"]
+}
diff --git a/apps/kimi-web/study-evals/fixtures/training-material/lesson.html b/apps/kimi-web/study-evals/fixtures/training-material/lesson.html
new file mode 100644
index 00000000..4bbb1ff5
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/training-material/lesson.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="zh-CN"><body>
+<h1>班前检查的结果必须改变是否启动车辆</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能按清单完成班前检查，并在发现液压油渗漏时作出停机判断，而不是把检查当作签字手续。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>安全检查只有在异常结果能阻止启动时才有意义。记录和签名用于留下责任链，但不能替代对制动、货叉、轮胎和管路的实际检查。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>检查不是“看过就算”，而是逐项确认能否安全工作。遇到材料明确列出的停机信号，应先让设备退出作业，再报告维修，不能用经验降低门槛。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="TR-1 班前检查">训练材料规定每班检查制动、货叉、轮胎和液压管路，并明确写出发现液压油渗漏时不得启动车辆。</p><p data-evidence="source" data-source-anchor="TR-2 行人与盲区">材料还要求通过视线受阻的转角前，驾驶员须减速、鸣笛，并让行人先行。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：班次紧张时发现管路下方有新油迹，驾驶员先停机挂牌并报告，而不是“先做一车再说”。这个情境用于演练，不是材料中的事故记录。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>认为“渗漏很少，不影响制动”是在自行增加例外。材料没有给出渗漏程度阈值，而是把发现液压油渗漏直接列为不得启动条件。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>逐项检查、记录结果、异常停机是一条完整动作链；遇到渗漏不启动，进入盲区则执行减速、鸣笛和让行。</p></section>
+<section id="self-check"><h2>自测题</h2><p>检查发现少量液压油渗漏但车辆还能制动，能否启动？不能。合格回答要指出停机条件不以驾驶员主观判断渗漏大小为准。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>TR-1 班前检查：四项检查、渗漏停机与记录要求；TR-2 行人与盲区：转角前的减速、鸣笛和让行动作。</p></section>
+</body></html>
diff --git a/apps/kimi-web/study-evals/fixtures/training-material/plan.json b/apps/kimi-web/study-evals/fixtures/training-material/plan.json
new file mode 100644
index 00000000..6ae1ad8c
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/training-material/plan.json
@@ -0,0 +1,25 @@
+{
+  "schemaVersion": 1,
+  "title": "从班前检查到事故处置",
+  "lessons": [
+    {
+      "order": 1,
+      "title": "识别必须停机的班前信号",
+      "objective": "完成四项班前检查并在发现液压油渗漏时停止启动车辆",
+      "sourceAnchors": ["TR-1 班前检查"]
+    },
+    {
+      "order": 2,
+      "title": "在盲区把行人优先落到动作",
+      "objective": "通过盲区前依次执行减速、鸣笛和让行动作",
+      "sourceAnchors": ["TR-2 行人与盲区"]
+    },
+    {
+      "order": 3,
+      "title": "碰撞后保护人员与现场",
+      "objective": "在十分钟报告并判断何时不得移动伤者",
+      "sourceAnchors": ["TR-3 事故处置"]
+    }
+  ],
+  "visibleDeferrals": []
+}
diff --git a/apps/kimi-web/study-evals/fixtures/training-material/source.md b/apps/kimi-web/study-evals/fixtures/training-material/source.md
new file mode 100644
index 00000000..ce6aa315
--- /dev/null
+++ b/apps/kimi-web/study-evals/fixtures/training-material/source.md
@@ -0,0 +1,15 @@
+# 仓库叉车班前安全训练（合成材料）
+
+本材料为 Kimi Study 质量评估原创合成文本，不替代真实设备手册或现场培训。
+
+## TR-1 班前检查
+
+每班作业前必须检查制动、货叉、轮胎和液压管路；发现液压油渗漏时不得启动车辆。检查结果需要记录在当班设备表中，并由驾驶员签名。
+
+## TR-2 行人与盲区
+
+通过视线受阻的转角前，驾驶员须减速、鸣笛，并让行人先行。载物遮挡前方视线时应倒车行驶，但坡道上不得采用这一做法。
+
+## TR-3 事故处置
+
+发生碰撞后 10 分钟内向值班主管报告；除现场存在继续伤害风险外，不得移动伤者。驾驶员应关闭车辆、设置警示并保留现场。
diff --git a/apps/kimi-web/study-evals/results/milestone-c.md b/apps/kimi-web/study-evals/results/milestone-c.md
new file mode 100644
index 00000000..39b5be55
--- /dev/null
+++ b/apps/kimi-web/study-evals/results/milestone-c.md
@@ -0,0 +1,32 @@
+# Milestone C offline evaluation result
+
+- Date: 2026-07-18
+- Skill contracts: `teach-quick-v3`, `teach-ria-v3`
+- Method: checked-in synthetic sources plus deterministic structural and grounding proxy
+- Command: `python apps/kimi-web/study-evals/evaluate_lessons.py`
+
+## Result
+
+| Measure | Result |
+|---|---:|
+| Fixture categories passed | 5 / 5 |
+| Incremental reference lessons generated and accepted | 5 / 5 |
+| Outline source anchors covered | 15 / 15 |
+| Required source facts inside source-labelled blocks | 10 / 10 |
+| Invalid or invented source anchors | 0 |
+| Deliberately unsupported forbidden claims present | 0 |
+| Repeated long learner-facing blocks | 0 |
+
+Passing categories: 产品说明、非虚构文章、技术指南、政策说明、培训材料。
+
+## Interpretation
+
+This result proves that the v3 contract, checker, fixture outlines, and reference
+lessons agree on the recorded source facts and structural quality obligations.
+Mutation tests separately prove that a fake anchor and an unsupported claim make
+the suite fail.
+
+It does not measure a live provider, latency, style preference across real
+learners, or arbitrary factual truth. A final browser E2E should generate from
+at least one fixture through a newly activated v3 Skill and inspect the result.
+No comparison with Coursebox or another product was performed.
diff --git a/apps/kimi-web/study-evals/rubrics/lesson-quality.md b/apps/kimi-web/study-evals/rubrics/lesson-quality.md
new file mode 100644
index 00000000..9a2d7a6b
--- /dev/null
+++ b/apps/kimi-web/study-evals/rubrics/lesson-quality.md
@@ -0,0 +1,34 @@
+# Chinese lesson quality rubric
+
+Score each dimension from 0 to 2. A severe fabrication fails the fixture even
+when the numeric total would otherwise pass.
+
+| Dimension | 0 | 1 | 2 | Deterministic proxy |
+|---|---|---|---|---|
+| Outline completeness | Meaningful source units disappear | Coverage exists but disposition is vague | Every declared anchor is taught or visibly deferred | `plan.json` anchor coverage |
+| Logical progression | Disconnected or inverted moves | Mostly ordered with weak prerequisite handling | Objective, explanation, example, boundary, practice form a teachable sequence | Required section order and progressive plan |
+| Source coverage | Important declared facts absent | Partial coverage | Required facts appear inside source-labelled evidence | Required source phrases |
+| Factual fidelity | Unsupported or contradictory claims | Ambiguous attribution | Source facts match declared anchors; teaching examples are separate | Anchor allow-list and forbidden claims |
+| Chinese readability | Translationese, filler, or mostly non-Chinese | Understandable but stiff | Natural, compact Chinese that explains difficult steps progressively | CJK ratio, section substance, filler patterns |
+| Explanation quality | Slogan or unexplained definition | One useful explanation | Conditions, reasoning, and boundary are made explicit | Core/plain/boundary sections |
+| Example quality | Invented example presented as source | Example labelled but weakly connected | Source example is traceable and transfer example is explicitly pedagogical | `data-evidence` markers |
+| Cross-lesson repetition | Repeated long paragraphs | Some avoidable restatement | No copied introduction, definition, or recap | Repeated-block detection |
+| Self-check alignment | Activity unrelated to objective | Topic matches but criterion is vague | Objective keyword and observable decision are tested with feedback | Objective keywords in objective and self-check |
+| Unsupported-fact ratio | One or more severe unsupported facts | Attribution gaps remain | No forbidden claim and no invalid source anchor | Forbidden-claim/invalid-anchor counts |
+
+## Severe failures
+
+Any of these makes a fixture fail:
+
+- an anchor not present in the fixture source;
+- a fabricated number, threshold, page, quotation, actor, or outcome;
+- a teaching example labelled as material evidence;
+- omission of a declared high-value source anchor without visible deferral;
+- a self-check whose expected answer contradicts the source;
+- copied learner-facing paragraphs across lessons.
+
+## Comparison rule
+
+Record the exact fixtures, contract revision, command, and scoring method for
+every result. Do not compare against another product without running the same
+sources, tasks, rubric, and review procedure on both systems.
diff --git a/apps/kimi-web/study-evals/test_evaluate_lessons.py b/apps/kimi-web/study-evals/test_evaluate_lessons.py
new file mode 100644
index 00000000..2547ca84
--- /dev/null
+++ b/apps/kimi-web/study-evals/test_evaluate_lessons.py
@@ -0,0 +1,100 @@
+from __future__ import annotations
+
+import importlib.util
+import json
+import shutil
+import tempfile
+import unittest
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parent
+MODULE_PATH = ROOT / "evaluate_lessons.py"
+SPEC = importlib.util.spec_from_file_location("evaluate_lessons", MODULE_PATH)
+EVALUATOR = importlib.util.module_from_spec(SPEC)
+assert SPEC and SPEC.loader
+SPEC.loader.exec_module(EVALUATOR)
+
+
+class ChineseLessonEvalTest(unittest.TestCase):
+    def test_all_five_categories_pass_the_recorded_reference_generation(self) -> None:
+        report = EVALUATOR.evaluate()
+        self.assertEqual(report["fixtureCount"], 5)
+        self.assertEqual(report["passedFixtures"], 5)
+        self.assertEqual(set(report["categories"]), EVALUATOR.EXPECTED_CATEGORIES)
+        self.assertEqual(report["globalErrors"], [])
+        self.assertEqual(report["metrics"]["invalidSourceAnchors"], 0)
+        self.assertEqual(report["metrics"]["unsupportedForbiddenClaims"], 0)
+        self.assertEqual(
+            report["metrics"]["requiredSourceFactCoverage"]["covered"],
+            report["metrics"]["requiredSourceFactCoverage"]["total"],
+        )
+
+    def test_fake_source_anchor_fails(self) -> None:
+        with tempfile.TemporaryDirectory() as temp:
+            fixtures = Path(temp) / "fixtures"
+            shutil.copytree(ROOT / "fixtures", fixtures)
+            lesson = fixtures / "product-instructions" / "lesson.html"
+            lesson.write_text(
+                lesson.read_text(encoding="utf-8").replace("P-2 指示灯状态", "P-99 不存在"),
+                encoding="utf-8",
+            )
+            report = EVALUATOR.evaluate(fixtures)
+            product = next(item for item in report["results"] if item["id"] == "product-instructions")
+            self.assertFalse(product["passed"])
+            self.assertTrue(any("invented or disallowed" in error for error in product["errors"]))
+
+    def test_unsupported_claim_fails(self) -> None:
+        with tempfile.TemporaryDirectory() as temp:
+            fixtures = Path(temp) / "fixtures"
+            shutil.copytree(ROOT / "fixtures", fixtures)
+            lesson = fixtures / "technical-guide" / "lesson.html"
+            lesson.write_text(
+                lesson.read_text(encoding="utf-8").replace(
+                    "</body>", "<p>所有 5xx 响应都必须无限重试。</p></body>",
+                ),
+                encoding="utf-8",
+            )
+            report = EVALUATOR.evaluate(fixtures)
+            technical = next(item for item in report["results"] if item["id"] == "technical-guide")
+            self.assertFalse(technical["passed"])
+            self.assertTrue(any("unsupported claim" in error for error in technical["errors"]))
+
+    def test_outline_omission_fails(self) -> None:
+        with tempfile.TemporaryDirectory() as temp:
+            fixtures = Path(temp) / "fixtures"
+            shutil.copytree(ROOT / "fixtures", fixtures)
+            plan_path = fixtures / "policy-notice" / "plan.json"
+            plan = json.loads(plan_path.read_text(encoding="utf-8"))
+            plan["lessons"] = plan["lessons"][:2]
+            plan_path.write_text(json.dumps(plan, ensure_ascii=False), encoding="utf-8")
+            report = EVALUATOR.evaluate(fixtures)
+            policy = next(item for item in report["results"] if item["id"] == "policy-notice")
+            self.assertFalse(policy["passed"])
+            self.assertTrue(any("outline omits source anchor" in error for error in policy["errors"]))
+
+    def test_ai_style_filler_fails(self) -> None:
+        with tempfile.TemporaryDirectory() as temp:
+            fixtures = Path(temp) / "fixtures"
+            shutil.copytree(ROOT / "fixtures", fixtures)
+            lesson = fixtures / "training-material" / "lesson.html"
+            lesson.write_text(
+                lesson.read_text(encoding="utf-8").replace(
+                    "逐项检查、记录结果",
+                    "在当今快速发展的时代，逐项检查、记录结果",
+                ),
+                encoding="utf-8",
+            )
+            report = EVALUATOR.evaluate(fixtures)
+            training = next(item for item in report["results"] if item["id"] == "training-material")
+            self.assertFalse(training["passed"])
+            self.assertTrue(any("AI-style filler" in error for error in training["errors"]))
+
+    def test_quick_and_deep_use_the_same_quality_gate(self) -> None:
+        quick = ROOT.parent / "study-skills/teach-quick/scripts/lesson_quality.py"
+        deep = ROOT.parent / "study-skills/teach-ria/scripts/lesson_quality.py"
+        self.assertEqual(quick.read_bytes(), deep.read_bytes())
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/apps/kimi-web/study-skills/AGENTS.md b/apps/kimi-web/study-skills/AGENTS.md
index 188a0c0a..fcee6079 100644
--- a/apps/kimi-web/study-skills/AGENTS.md
+++ b/apps/kimi-web/study-skills/AGENTS.md
@@ -4,8 +4,8 @@ These instructions apply to `apps/kimi-web/study-skills/**`.
 
 ## Contracts
 
-- `teach-quick` advertises `[contract:teach-quick-v2]` and writes survey evidence only.
-- `teach-ria` advertises `[contract:teach-ria-v2]` and preserves all whole-reading/RIA fidelity gates.
+- `teach-quick` advertises `[contract:teach-quick-v4]` and writes survey evidence only.
+- `teach-ria` advertises `[contract:teach-ria-v4]` and preserves all whole-reading/RIA fidelity gates.
 - Both write `source/STUDY-SNAPSHOT.json` for `kimi-study-foundation-v1`.
 - `CONTRACT.json`, Skill frontmatter, `src/study/domain/studyPolicy.ts`, runtime checks, and tests must agree.
 
diff --git a/apps/kimi-web/study-skills/teach-quick/CONTRACT.json b/apps/kimi-web/study-skills/teach-quick/CONTRACT.json
index 9be90e02..3c58864a 100644
--- a/apps/kimi-web/study-skills/teach-quick/CONTRACT.json
+++ b/apps/kimi-web/study-skills/teach-quick/CONTRACT.json
@@ -1,6 +1,6 @@
 {
   "name": "teach-quick",
-  "contractRevision": "teach-quick-v2",
+  "contractRevision": "teach-quick-v4",
   "productContractRevision": "kimi-study-foundation-v1",
   "upstream": {
     "repository": "https://github.com/mattpocock/skills",
diff --git a/apps/kimi-web/study-skills/teach-quick/LESSON-QUALITY-FORMAT.md b/apps/kimi-web/study-skills/teach-quick/LESSON-QUALITY-FORMAT.md
new file mode 100644
index 00000000..2a360cb5
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-quick/LESSON-QUALITY-FORMAT.md
@@ -0,0 +1,77 @@
+# Chinese lesson quality contract
+
+This contract applies to every published `lessons/*.html` file. It is a set of
+teaching and evidence obligations, not a prose template: section length,
+examples, and ordering should follow the source and the learner's Mission.
+
+## Learner-facing structure
+
+Use one `<h1>` and `<html lang="zh-CN">`. A lesson must make these moves visible:
+
+| Move | HTML id | Purpose |
+|---|---|---|
+| Learning objective | `learning-objective` | One observable capability, not “understand the chapter”. |
+| Core concept | `core-concept` | The source idea with its conditions and scope. |
+| Plain explanation | `plain-explanation` | Natural Chinese that explains the difficult step progressively. |
+| Source example | `source-example` or `original-case` | A traceable example actually supported by the material. |
+| Application example | `application-example` or `transfer-example` | A clearly labelled teaching example, never disguised as source fact. |
+| Misconception or boundary | `misconception` or `boundary-misconception` | A plausible misuse, counterexample, or limit. |
+| Lesson summary | `lesson-summary` | A compact decision rule or reasoning chain, not an AI-style recap. |
+| Self-check | `self-check` or `practice-feedback` | A task aligned to the objective plus answer logic or immediate feedback. |
+| Source anchors | `source-anchors` | Every stable source location used in the lesson. |
+
+Do not repeat a generic definition, welcome paragraph, motivational sentence,
+or identical summary across lessons. Retrieve prior knowledge only when it is
+needed for the current move.
+
+## Evidence labelling
+
+Wrap source-grounded claims or cases in a visible block with both attributes:
+
+```html
+<p data-evidence="source" data-source-anchor="第 2 节：状态指示灯">
+  材料中说明：蓝灯慢闪表示设备正在等待配对。
+</p>
+```
+
+The anchor must be a real, stable location reopened during authoring. Generic
+values such as `原文`, `材料`, or `参考资料` are invalid. List the same anchor
+verbatim in `source-anchors`.
+
+Wrap an invented teaching transfer separately:
+
+```html
+<p data-evidence="teaching-example">
+  教学示例：把指示灯当作排查入口。这个情境用于练习，不是材料中的真实案例。
+</p>
+```
+
+If the source cannot support a requested example or factual detail, say
+`资料中未找到可核验依据` and omit the claim. Never create a page number,
+quotation, actor, outcome, statistic, policy threshold, or technical behavior.
+
+## Chinese writing rules
+
+- Write idiomatic, compact Chinese; reorganize source syntax instead of
+  translating English sentence order.
+- Start from the learner's concrete difficulty. Avoid ceremonial introductions,
+  motivational filler, and “让我们开启学习之旅” language.
+- Explain one hard step at a time. Keep source facts, teaching examples, and
+  uncertainty visibly distinct.
+- Preserve the source's complete reasoning and boundary when compression would
+  turn it into a slogan.
+- Use examples only when they expose the concept or decision rule.
+- Make self-check feedback explain why an answer succeeds or fails.
+
+## Publication gate
+
+Before adding a lesson to `lessons/index.json`:
+
+1. reopen every named source anchor;
+2. compare every source-labelled claim against that location;
+3. run the course checker, which applies `scripts/lesson_quality.py`;
+4. compare published lessons for repeated learner-facing paragraphs;
+5. publish the HTML, lesson index, and snapshot in the documented atomic order.
+
+Structural checks cannot prove factual truth. Passing them is permission to
+publish only after the semantic source comparison above is complete.
diff --git a/apps/kimi-web/study-skills/teach-quick/LESSON-REVISION-FORMAT.md b/apps/kimi-web/study-skills/teach-quick/LESSON-REVISION-FORMAT.md
new file mode 100644
index 00000000..300eff1b
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-quick/LESSON-REVISION-FORMAT.md
@@ -0,0 +1,38 @@
+# Current lesson revision workflow
+
+Kimi Study may ask this Skill to revise or regenerate exactly one published lesson. The request supplies a course id, a `lessons/<safe-name>.html` path, a base content revision, and an operation id. A revision request also supplies one learner instruction.
+
+## Non-negotiable boundaries
+
+- Inspect the current lesson, `lessons/index.json`, the approved plan, and its cited source ranges before drafting.
+- Keep the course id, lesson path, indexed title, plan revision, publication status, generation counts, and every other lesson unchanged.
+- Preserve the exact existing `data-source-anchor` set. Reopen those source locations and keep source facts distinct from teaching examples.
+- Never write directly over the published lesson while drafting. Use `.study-drafts/<same-file-name>.html`.
+- A stale base revision, missing source, invalid candidate, changed title, or changed anchor set is a hard stop. Leave the published lesson untouched and report the reason.
+
+## Guarded publication
+
+1. Confirm the current identity before work begins:
+
+   ```bash
+   python3 scripts/lesson_revision.py \
+     --workspace "$PWD" \
+     --lesson lessons/0001-example.html \
+     --expect fnv1a32:12345678
+   ```
+
+2. Draft only `.study-drafts/0001-example.html`. For a revision, apply the learner's instruction without unrelated rewrites. For regeneration, rebuild the explanation and examples while retaining the same learning objective, title, and source anchors.
+3. Validate the draft with the mode's lesson checker. Run the full course checker too, so cross-lesson repetition and publication invariants still pass.
+4. Immediately before replacement, atomically publish through the guard:
+
+   ```bash
+   python3 scripts/lesson_revision.py \
+     --workspace "$PWD" \
+     --lesson lessons/0001-example.html \
+     --expect fnv1a32:12345678 \
+     --candidate .study-drafts/0001-example.html
+   ```
+
+5. Run the full checker again. Do not change `source/STUDY-SNAPSHOT.json` merely to signal success: the published lesson content is the authoritative revision, and the existing lesson index remains valid because identity and status did not change.
+
+The revision token is FNV-1a over UTF-8 bytes, formatted as `fnv1a32:` plus eight lowercase hexadecimal digits. It is a stale-write identity, not a cryptographic claim.
diff --git a/apps/kimi-web/study-skills/teach-quick/SKILL.md b/apps/kimi-web/study-skills/teach-quick/SKILL.md
index 95475c0e..854d7341 100644
--- a/apps/kimi-web/study-skills/teach-quick/SKILL.md
+++ b/apps/kimi-web/study-skills/teach-quick/SKILL.md
@@ -1,6 +1,6 @@
 ---
 name: teach-quick
-description: "[contract:teach-quick-v2] Survey an uploaded learning source end to end, clarify the learner's Mission with at most one question, and build the fastest honest course path. Use for Kimi Study quick mode when the learner is still deciding how deeply to study a book, document, transcript, or mixed set of learning materials."
+description: "[contract:teach-quick-v4] Survey an uploaded learning source end to end, clarify the learner's Mission with at most one question, and build the fastest honest Chinese course path. Use for Kimi Study quick mode when the learner is still deciding how deeply to study a book, document, transcript, or mixed set of learning materials."
 ---
 
 # Teach Quick
@@ -23,7 +23,7 @@ Maintain these artifacts as they become relevant:
 - `source/QUICK-SURVEY.md`: traceable survey of the entire supplied material. Follow [QUICK-SURVEY-FORMAT.md](./QUICK-SURVEY-FORMAT.md).
 - `source/QUICK-PLAN.md`: mission-bound outline. Follow [QUICK-PLAN-FORMAT.md](./QUICK-PLAN-FORMAT.md).
 - `MISSION.md`: concrete learner outcome. Follow [MISSION-FORMAT.md](./MISSION-FORMAT.md).
-- `lessons/*.html`: short numbered lessons published incrementally.
+- `lessons/*.html`: short numbered lessons published incrementally. Follow [LESSON-QUALITY-FORMAT.md](./LESSON-QUALITY-FORMAT.md). Current-lesson replacements also follow [LESSON-REVISION-FORMAT.md](./LESSON-REVISION-FORMAT.md).
 - `lessons/index.json`: versioned lesson title/order/publication manifest. Follow [LESSON-INDEX-FORMAT.md](./LESSON-INDEX-FORMAT.md).
 - `reference/*.html`: durable quick-reference artifacts.
 - `learning-records/*.md`: evidence-backed changes in understanding. Follow [LEARNING-RECORD-FORMAT.md](./LEARNING-RECORD-FORMAT.md).
@@ -71,7 +71,7 @@ Never write `actor=user` unless the learner actually performed an explicit exper
 
 ### 1. Initialize
 
-Create or update `source/STUDY-SNAPSHOT.json` with mode `quick`, Skill pin `teach-quick-v2`, source status `surveying`, Mission status `not_started` or `interviewing`, and plan/generation status `not_started`.
+Create or update `source/STUDY-SNAPSHOT.json` with mode `quick`, Skill pin `teach-quick-v4`, source status `surveying`, Mission status `not_started` or `interviewing`, and plan/generation status `not_started`.
 
 ### 2. Survey the source
 
@@ -87,24 +87,48 @@ Do not design the course until both the survey revision and Mission revision are
 
 After the plan passes `python3 scripts/check-quick-course.py --workspace /absolute/workspace`, set plan status `ready` in the snapshot. Stop and return control to Kimi Study so the learner can see the outline before generation.
 
+### 4a. Revise the visible outline on request
+
+When Kimi Study sends a learner instruction naming the exact current plan revision:
+
+- reopen the current survey, Mission, plan, and snapshot; reject the request if the named revision is stale;
+- interpret ordinary Chinese requests about the audience, emphasis, lesson count, or teaching order without asking the learner to edit internal files;
+- revise only this course's plan; do not create another course, restart source surveying, or begin lesson generation;
+- give the candidate a new stable plan revision and keep its source and Mission pins exact;
+- keep the last ready `QUICK-PLAN.md` and snapshot authoritative while drafting and checking the candidate;
+- replace `source/QUICK-PLAN.md` and its snapshot plan fields only after every plan integrity check passes; if revision fails, leave both authoritative artifacts unchanged and report the failure;
+- stop and return control after publishing the new ready revision so Kimi Study can show it for learner confirmation.
+
+Changing the outline does not authorize inventing unsupported source content or silently changing the learner's Mission. If the request conflicts with the source or Mission, retain the current revision and explain the conflict in learner-facing Chinese.
+
 ### 5. Generate on request
 
 Only generate when the request names the exact current plan revision. Ignore or reject stale generation requests.
 
 Publish lessons incrementally as `lessons/NNNN-dash-case-name.html`. After validating each lesson, update `lessons/index.json` first, then set `publishedLessons` in the snapshot to the manifest's published count and set generation status `partially_ready`. Set it to `ready` only when every indexed lesson is published and every planned reference destination exists.
 
+Before authoring the first lesson, read [LESSON-QUALITY-FORMAT.md](./LESSON-QUALITY-FORMAT.md). Write learner-facing content in natural Chinese. The visible learning moves are obligations, not a mechanical template: spend space on the source's actual difficulty and omit unsupported detail instead of padding every section.
+
 Each lesson must:
 
 - teach one tightly scoped move tied to the Mission;
 - cite stable locations in the supplied source;
+- label source-grounded blocks with their exact anchors and label invented teaching transfers separately;
+- state one observable learning objective, explain the hard step progressively, and end with an aligned self-check plus immediate answer logic;
 - distinguish source claims from external corrections;
 - include a retrieval or practice loop with immediate feedback;
 - preserve important cases and boundaries instead of reducing them to slogans;
 - link to relevant lessons and reference artifacts;
 - invite follow-up questions from the tutor.
 
+Before publication, run `python3 scripts/check-quick-course.py --workspace /absolute/workspace --lesson lessons/NNNN-name.html`. After the lesson index and snapshot advance, run the full checker again so cross-lesson repetition and publication counts are checked. A structural pass never replaces reopening and semantically comparing every source anchor.
+
 Use high-trust external sources only to correct, update, or clarify the uploaded material. Never replace missing source content with parametric guesses.
 
+### 5a. Revise or regenerate one published lesson
+
+When Kimi Study names an exact lesson path, base content revision, and operation id, read [LESSON-REVISION-FORMAT.md](./LESSON-REVISION-FORMAT.md) before acting. Reject stale revisions. Draft and validate only the named lesson, preserve its indexed identity and exact source-anchor set, then publish through `scripts/lesson_revision.py`. Do not create a course, change the plan, alter generation counts, or touch another lesson. A failed check leaves the published lesson unchanged.
+
 ## Upgrade boundary
 
 If the learner asks for deep study, do not simulate it inside quick mode. Preserve the uploaded source identity and quick artifacts, then let Kimi Study activate `teach-ria`. Quick evidence remains a useful survey but never becomes deep certification.
diff --git a/apps/kimi-web/study-skills/teach-quick/STUDY-SNAPSHOT-FORMAT.md b/apps/kimi-web/study-skills/teach-quick/STUDY-SNAPSHOT-FORMAT.md
index fadbbe25..967fd7ea 100644
--- a/apps/kimi-web/study-skills/teach-quick/STUDY-SNAPSHOT-FORMAT.md
+++ b/apps/kimi-web/study-skills/teach-quick/STUDY-SNAPSHOT-FORMAT.md
@@ -11,7 +11,7 @@ Required identity:
   "courseId": "course-from-activation-args",
   "profile": {
     "mode": "quick",
-    "skill": { "name": "teach-quick", "contractRevision": "teach-quick-v2" },
+    "skill": { "name": "teach-quick", "contractRevision": "teach-quick-v4" },
     "sourceRevision": "exact-source-revision",
     "selectedBy": "user"
   }
diff --git a/apps/kimi-web/study-skills/teach-quick/scripts/check-quick-course.py b/apps/kimi-web/study-skills/teach-quick/scripts/check-quick-course.py
index da2770a3..62bfe727 100644
--- a/apps/kimi-web/study-skills/teach-quick/scripts/check-quick-course.py
+++ b/apps/kimi-web/study-skills/teach-quick/scripts/check-quick-course.py
@@ -9,6 +9,9 @@
 import sys
 from pathlib import Path
 
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+from lesson_quality import find_repeated_blocks, validate_lesson_html
+
 
 def read_text(path: Path) -> str:
     try:
@@ -62,6 +65,7 @@ def validate_lesson_index(workspace: Path, snapshot: dict, errors: list[str]) ->
         return
 
     seen_paths: set[str] = set()
+    published_documents: dict[str, str] = {}
     published_count = 0
     all_published = True
     for index, lesson in enumerate(lessons, start=1):
@@ -87,8 +91,14 @@ def validate_lesson_index(workspace: Path, snapshot: dict, errors: list[str]) ->
             all_published = False
         elif status == "published":
             published_count += 1
-            if isinstance(path, str) and not (workspace / path).is_file():
-                errors.append(f"lessons/index.json: published lesson is missing: {path}")
+            if isinstance(path, str):
+                lesson_path = workspace / path
+                if not lesson_path.is_file():
+                    errors.append(f"lessons/index.json: published lesson is missing: {path}")
+                elif re.fullmatch(r"lessons/[A-Za-z0-9][A-Za-z0-9._-]*\.html", path):
+                    lesson_source = read_text(lesson_path)
+                    published_documents[path] = lesson_source
+                    errors.extend(validate_lesson_html(lesson_source, path))
         else:
             all_published = False
 
@@ -96,6 +106,10 @@ def validate_lesson_index(workspace: Path, snapshot: dict, errors: list[str]) ->
         errors.append("lessons/index.json: published count does not match STUDY-SNAPSHOT.json")
     if generation.get("status") == "ready" and not all_published:
         errors.append("lessons/index.json: ready generation requires every lesson to be published")
+    errors.extend(
+        f"lessons/index.json: {error}"
+        for error in find_repeated_blocks(published_documents)
+    )
 
 
 def validate(workspace: Path) -> list[str]:
@@ -154,7 +168,7 @@ def validate(workspace: Path) -> list[str]:
     if snapshot.get("schemaVersion") != 1 or snapshot.get("contractRevision") != "kimi-study-foundation-v1":
         errors.append("STUDY-SNAPSHOT.json: unsupported product contract")
     if not isinstance(profile, dict) or profile.get("mode") != "quick" or profile.get("skill") != {
-        "name": "teach-quick", "contractRevision": "teach-quick-v2"
+        "name": "teach-quick", "contractRevision": "teach-quick-v4"
     }:
         errors.append("STUDY-SNAPSHOT.json: quick profile pin is invalid")
     if not isinstance(source, dict) or source.get("revision") != source_revision:
@@ -178,9 +192,27 @@ def validate(workspace: Path) -> list[str]:
 def main() -> int:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("--workspace", type=Path, default=Path.cwd())
+    parser.add_argument("--lesson", type=Path, help="Validate one candidate lesson before publication")
     args = parser.parse_args()
     workspace = args.workspace.expanduser().resolve()
     errors = validate(workspace)
+    if args.lesson is not None:
+        lesson = args.lesson.expanduser()
+        lesson = lesson.resolve() if lesson.is_absolute() else (workspace / lesson).resolve()
+        try:
+            relative = lesson.relative_to(workspace).as_posix()
+        except ValueError:
+            errors.append("candidate lesson must stay inside the course workspace")
+        else:
+            if not re.fullmatch(
+                r"(?:lessons|\.study-drafts)/[A-Za-z0-9][A-Za-z0-9._-]*\.html",
+                relative,
+            ):
+                errors.append("candidate lesson path is unsafe")
+            elif not lesson.is_file():
+                errors.append(f"candidate lesson is missing: {relative}")
+            else:
+                errors.extend(validate_lesson_html(read_text(lesson), relative))
     if errors:
         print("Quick-course gate failed:", file=sys.stderr)
         for error in errors:
diff --git a/apps/kimi-web/study-skills/teach-quick/scripts/lesson_quality.py b/apps/kimi-web/study-skills/teach-quick/scripts/lesson_quality.py
new file mode 100644
index 00000000..da2c86ad
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-quick/scripts/lesson_quality.py
@@ -0,0 +1,185 @@
+#!/usr/bin/env python3
+"""Deterministic structural gates for learner-facing Chinese lesson HTML."""
+
+from __future__ import annotations
+
+import html
+import re
+from collections import defaultdict
+
+
+SECTION_GROUPS: dict[str, tuple[str, ...]] = {
+    "learning-objective": ("learning-objective",),
+    "core-concept": ("core-concept",),
+    "plain-explanation": ("plain-explanation",),
+    "source-example": ("source-example", "original-case"),
+    "application-example": ("application-example", "transfer-example"),
+    "misconception": ("misconception", "boundary-misconception"),
+    "lesson-summary": ("lesson-summary",),
+    "self-check": ("self-check", "practice-feedback"),
+    "source-anchors": ("source-anchors",),
+}
+
+AI_FILLER_PATTERNS = tuple(
+    re.compile(pattern)
+    for pattern in (
+        r"在当今快速发展的时代",
+        r"让我们(?:一起|来)(?:深入|共同)?(?:探索|学习|开启)",
+        r"开启.{0,12}(?:学习|知识)之旅",
+        r"(?:综上所述|总而言之)",
+        r"不难发现",
+        r"至关重要",
+    )
+)
+
+GENERIC_ANCHORS = {"原文", "材料", "资料", "来源", "见原文", "参考资料"}
+ATTRIBUTE_RE = re.compile(
+    r"(?P<name>[a-zA-Z_:][-a-zA-Z0-9_:.]*)\s*=\s*(?P<quote>['\"])(?P<value>.*?)(?P=quote)",
+    re.DOTALL,
+)
+
+
+def _attributes(fragment: str) -> dict[str, str]:
+    return {
+        match.group("name").lower(): html.unescape(match.group("value")).strip()
+        for match in ATTRIBUTE_RE.finditer(fragment)
+    }
+
+
+def _visible_text(source: str) -> str:
+    cleaned = re.sub(r"<!--.*?-->", " ", source, flags=re.DOTALL)
+    cleaned = re.sub(r"<(?:script|style)\b.*?</(?:script|style)\s*>", " ", cleaned, flags=re.I | re.S)
+    cleaned = re.sub(r"<[^>]+>", " ", cleaned)
+    return re.sub(r"\s+", " ", html.unescape(cleaned)).strip()
+
+
+def _section(source: str, section_id: str) -> tuple[int, str]:
+    match = re.search(
+        rf"<(?P<tag>[a-z][\w:-]*)\b[^>]*\bid=['\"]{re.escape(section_id)}['\"][^>]*>"
+        rf"(?P<body>.*?)</(?P=tag)\s*>",
+        source,
+        re.IGNORECASE | re.DOTALL,
+    )
+    if match is None:
+        return (-1, "")
+    return (match.start(), _visible_text(match.group("body")))
+
+
+def _evidence_elements(source: str) -> list[dict[str, str]]:
+    elements: list[dict[str, str]] = []
+    pattern = re.compile(
+        r"<(?P<tag>[a-z][\w:-]*)\b(?P<attrs>[^>]*\bdata-evidence\s*=\s*['\"][^'\"]+['\"][^>]*)>"
+        r"(?P<body>.*?)</(?P=tag)\s*>",
+        re.IGNORECASE | re.DOTALL,
+    )
+    for match in pattern.finditer(source):
+        attrs = _attributes(match.group("attrs"))
+        elements.append({
+            "kind": attrs.get("data-evidence", ""),
+            "anchor": attrs.get("data-source-anchor", ""),
+            "text": _visible_text(match.group("body")),
+        })
+    return elements
+
+
+def inspect_lesson_html(source: str) -> dict[str, object]:
+    sections: dict[str, str] = {}
+    positions: dict[str, int] = {}
+    for canonical, aliases in SECTION_GROUPS.items():
+        candidates = [(_section(source, alias), alias) for alias in aliases]
+        present = [(position, text, alias) for (position, text), alias in candidates if position >= 0]
+        if present:
+            position, text, _ = min(present, key=lambda item: item[0])
+            positions[canonical] = position
+            sections[canonical] = text
+        else:
+            positions[canonical] = -1
+            sections[canonical] = ""
+
+    evidence = _evidence_elements(source)
+    source_evidence = [item for item in evidence if item["kind"] == "source"]
+    teaching_examples = [item for item in evidence if item["kind"] == "teaching-example"]
+    anchors = [item["anchor"] for item in source_evidence if item["anchor"]]
+    visible = _visible_text(source)
+    cjk_count = len(re.findall(r"[\u3400-\u9fff]", visible))
+    readable_count = len(re.findall(r"[\w\u3400-\u9fff]", visible))
+
+    blocks: list[str] = []
+    for match in re.finditer(r"<(?:p|li)\b[^>]*>(.*?)</(?:p|li)\s*>", source, re.I | re.S):
+        block = _visible_text(match.group(1))
+        if len(block) >= 40:
+            blocks.append(block)
+
+    return {
+        "sections": sections,
+        "positions": positions,
+        "sourceEvidence": source_evidence,
+        "teachingExamples": teaching_examples,
+        "anchors": anchors,
+        "visibleText": visible,
+        "cjkCount": cjk_count,
+        "cjkRatio": cjk_count / max(readable_count, 1),
+        "blocks": blocks,
+    }
+
+
+def validate_lesson_html(source: str, label: str = "lesson") -> list[str]:
+    errors: list[str] = []
+    report = inspect_lesson_html(source)
+    sections = report["sections"]
+    assert isinstance(sections, dict)
+
+    if not re.search(r"<html\b[^>]*\blang=['\"]zh(?:-CN)?['\"]", source, re.I):
+        errors.append(f"{label}: html language must be zh-CN")
+    if len(re.findall(r"<h1\b", source, re.I)) != 1:
+        errors.append(f"{label}: exactly one visible h1 is required")
+    for canonical in SECTION_GROUPS:
+        text = str(sections.get(canonical, ""))
+        if not text:
+            errors.append(f"{label}: missing lesson quality section {canonical}")
+        elif len(text) < 16:
+            errors.append(f"{label}: lesson quality section {canonical} is too thin")
+
+    if int(report["cjkCount"]) < 120 or float(report["cjkRatio"]) < 0.45:
+        errors.append(f"{label}: learner-facing content is not substantial natural Chinese")
+
+    visible = str(report["visibleText"])
+    for pattern in AI_FILLER_PATTERNS:
+        if pattern.search(visible):
+            errors.append(f"{label}: contains generic AI-style filler matched by {pattern.pattern}")
+
+    source_evidence = report["sourceEvidence"]
+    teaching_examples = report["teachingExamples"]
+    assert isinstance(source_evidence, list) and isinstance(teaching_examples, list)
+    if not source_evidence:
+        errors.append(f"{label}: requires at least one source-grounded evidence block")
+    if not teaching_examples:
+        errors.append(f"{label}: requires a teaching example explicitly separated from source facts")
+
+    anchor_section = str(sections.get("source-anchors", ""))
+    for item in source_evidence:
+        anchor = str(item.get("anchor", "")).strip()
+        if not anchor or anchor in GENERIC_ANCHORS or "{" in anchor or "TODO" in anchor.upper():
+            errors.append(f"{label}: source evidence has a missing or unstable anchor")
+        elif anchor not in anchor_section:
+            errors.append(f"{label}: source anchor {anchor!r} is absent from source-anchors")
+
+    positions = report["positions"]
+    assert isinstance(positions, dict)
+    quick_order = [positions[key] for key in SECTION_GROUPS if int(positions[key]) >= 0]
+    if quick_order != sorted(quick_order):
+        errors.append(f"{label}: lesson quality sections are not in a coherent learning order")
+    return errors
+
+
+def find_repeated_blocks(documents: dict[str, str]) -> list[str]:
+    owners: dict[str, set[str]] = defaultdict(set)
+    for label, source in documents.items():
+        report = inspect_lesson_html(source)
+        for block in report["blocks"]:
+            owners[re.sub(r"\s+", " ", str(block)).strip()].add(label)
+    return [
+        f"repeated learner-facing block across {', '.join(sorted(labels))}: {block[:80]}"
+        for block, labels in sorted(owners.items())
+        if len(labels) > 1
+    ]
diff --git a/apps/kimi-web/study-skills/teach-quick/scripts/lesson_revision.py b/apps/kimi-web/study-skills/teach-quick/scripts/lesson_revision.py
new file mode 100644
index 00000000..c14d48e1
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-quick/scripts/lesson_revision.py
@@ -0,0 +1,123 @@
+#!/usr/bin/env python3
+"""Guard and atomically publish one Kimi Study lesson revision."""
+
+from __future__ import annotations
+
+import argparse
+import html
+import os
+import re
+import sys
+from pathlib import Path
+
+from lesson_quality import inspect_lesson_html, validate_lesson_html
+
+
+LESSON_PATH = re.compile(r"lessons/[A-Za-z0-9][A-Za-z0-9._-]*\.html")
+DRAFT_PATH = re.compile(r"\.study-drafts/[A-Za-z0-9][A-Za-z0-9._-]*\.html")
+REVISION = re.compile(r"fnv1a32:[0-9a-f]{8}")
+
+
+def lesson_revision(source: str) -> str:
+    value = 0x811C9DC5
+    for byte in source.encode("utf-8"):
+        value ^= byte
+        value = (value * 0x01000193) & 0xFFFFFFFF
+    return f"fnv1a32:{value:08x}"
+
+
+def read_text(path: Path) -> str:
+    return path.read_text(encoding="utf-8")
+
+
+def visible_title(source: str) -> str:
+    match = re.search(r"<title>(.*?)</title>", source, re.I | re.S)
+    if match is None:
+        match = re.search(r"<h1\b[^>]*>(.*?)</h1\s*>", source, re.I | re.S)
+    if match is None:
+        return ""
+    return re.sub(r"\s+", " ", html.unescape(re.sub(r"<[^>]+>", " ", match.group(1)))).strip()
+
+
+def workspace_path(workspace: Path, value: str, pattern: re.Pattern[str]) -> Path:
+    workspace = workspace.resolve()
+    if pattern.fullmatch(value) is None:
+        raise ValueError(f"unsafe lesson revision path: {value}")
+    resolved = (workspace / value).resolve()
+    try:
+        resolved.relative_to(workspace)
+    except ValueError as error:
+        raise ValueError(f"lesson revision path leaves workspace: {value}") from error
+    return resolved
+
+
+def assert_revision(target: Path, expected: str) -> str:
+    if REVISION.fullmatch(expected) is None:
+        raise ValueError("expected lesson revision is malformed")
+    current = lesson_revision(read_text(target))
+    if current != expected:
+        raise ValueError(f"stale lesson revision: expected {expected}, found {current}")
+    return current
+
+
+def publish_candidate(workspace: Path, lesson: str, candidate: str, expected: str) -> str:
+    target = workspace_path(workspace, lesson, LESSON_PATH)
+    draft = workspace_path(workspace, candidate, DRAFT_PATH)
+    if target.name != draft.name:
+        raise ValueError("candidate filename must preserve lesson identity")
+    assert_revision(target, expected)
+
+    current_source = read_text(target)
+    candidate_source = read_text(draft)
+    errors = validate_lesson_html(candidate_source, lesson)
+    if errors:
+        raise ValueError(f"candidate lesson failed quality gates: {errors[0]}")
+    if visible_title(candidate_source) != visible_title(current_source):
+        raise ValueError("candidate lesson title must match the published lesson")
+
+    current_anchors = set(inspect_lesson_html(current_source)["anchors"])
+    candidate_anchors = set(inspect_lesson_html(candidate_source)["anchors"])
+    if candidate_anchors != current_anchors:
+        raise ValueError("candidate source anchors must exactly match the published lesson")
+
+    # Re-check immediately before replace; another operation may have won
+    # while the candidate was being validated.
+    assert_revision(target, expected)
+    with draft.open("rb") as handle:
+        os.fsync(handle.fileno())
+    os.replace(draft, target)
+    directory = os.open(target.parent, os.O_RDONLY)
+    try:
+        os.fsync(directory)
+    finally:
+        os.close(directory)
+    return lesson_revision(read_text(target))
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--workspace", type=Path, default=Path.cwd())
+    parser.add_argument("--lesson", required=True)
+    parser.add_argument("--expect")
+    parser.add_argument("--candidate")
+    args = parser.parse_args()
+    workspace = args.workspace.expanduser().resolve()
+    try:
+        target = workspace_path(workspace, args.lesson, LESSON_PATH)
+        if args.candidate is None:
+            revision = lesson_revision(read_text(target))
+            if args.expect is not None:
+                assert_revision(target, args.expect)
+        else:
+            if args.expect is None:
+                raise ValueError("--candidate requires --expect")
+            revision = publish_candidate(workspace, args.lesson, args.candidate, args.expect)
+    except (OSError, UnicodeError, ValueError) as error:
+        print(f"Lesson revision refused: {error}", file=sys.stderr)
+        return 1
+    print(revision)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/apps/kimi-web/study-skills/teach-quick/tests/test_quick_gate.py b/apps/kimi-web/study-skills/teach-quick/tests/test_quick_gate.py
index bd4a2632..3c6ae687 100644
--- a/apps/kimi-web/study-skills/teach-quick/tests/test_quick_gate.py
+++ b/apps/kimi-web/study-skills/teach-quick/tests/test_quick_gate.py
@@ -14,6 +14,22 @@
 SPEC.loader.exec_module(CHECKER)
 
 
+def quality_lesson_html(anchor: str = "测试材料 §1", marker: str = "状态判断") -> str:
+    return f"""<!doctype html>
+<html lang="zh-CN"><body>
+<h1>{marker}：先看证据，再决定动作</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能依据材料中的状态信号和适用条件，判断下一步是否应该继续操作，并说明判断理由。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>可靠判断不是记住一句口号，而是把可观察信号、材料给出的条件和允许采取的动作连成一条可核对的推理链。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>先确认眼前发生了什么，再到材料中找到对应条件，最后只选择材料允许的动作。任何一步缺少依据，都应停下来补证据。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="{anchor}">材料中说明：测试状态出现后应先核对限制条件，再决定继续、等待或停止，不能跳过条件直接行动。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：把一个新的状态提示代入“信号—条件—动作”三步法。这个情境用于练习，不是材料中的真实案例。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>看到熟悉信号就凭经验行动是常见误区；如果适用条件已经变化，相同信号可能需要完全不同的处理方式。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>保留这一条判断规则：描述信号，核对条件，再选择材料明确允许的动作；缺少证据时不要补写结论。</p></section>
+<section id="self-check"><h2>自测题</h2><p>请判断：只有状态信号、没有适用条件时能否继续？答案是不能；合格回答应指出缺少哪项证据以及应先查哪里。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>{anchor}：本节关于状态、条件和动作顺序的直接依据，发布前已按该稳定位置重新核对。</p></section>
+</body></html>"""
+
+
 class QuickGateTest(unittest.TestCase):
     def setUp(self) -> None:
         self.temp = tempfile.TemporaryDirectory()
@@ -61,7 +77,7 @@ def setUp(self) -> None:
             "courseId": "course-12345678",
             "profile": {
                 "mode": "quick",
-                "skill": {"name": "teach-quick", "contractRevision": "teach-quick-v2"},
+                "skill": {"name": "teach-quick", "contractRevision": "teach-quick-v4"},
                 "sourceRevision": "file:file-1",
                 "selectedBy": "user",
             },
@@ -101,7 +117,7 @@ def _write_snapshot(self) -> None:
     def _publish_lesson_index(self, *, status: str = "partially_ready") -> None:
         lessons = self.workspace / "lessons"
         lessons.mkdir(exist_ok=True)
-        (lessons / "0001-first.html").write_text("<h1>First lesson</h1>", encoding="utf-8")
+        (lessons / "0001-first.html").write_text(quality_lesson_html(), encoding="utf-8")
         (lessons / "index.json").write_text(
             json.dumps(
                 {
@@ -111,7 +127,7 @@ def _publish_lesson_index(self, *, status: str = "partially_ready") -> None:
                         {
                             "order": 1,
                             "path": "lessons/0001-first.html",
-                            "title": "First lesson",
+                            "title": "先看证据，再决定动作",
                             "status": "published",
                         }
                     ],
@@ -125,6 +141,20 @@ def _publish_lesson_index(self, *, status: str = "partially_ready") -> None:
     def test_valid_quick_course_passes(self) -> None:
         self.assertEqual(CHECKER.validate(self.workspace), [])
 
+    def test_revised_plan_and_snapshot_must_publish_the_same_revision(self) -> None:
+        plan_path = self.workspace / "source/QUICK-PLAN.md"
+        plan_path.write_text(
+            plan_path.read_text(encoding="utf-8").replace("plan-v1", "plan-v2"),
+            encoding="utf-8",
+        )
+
+        errors = CHECKER.validate(self.workspace)
+        self.assertTrue(any("plan revision is not ready" in error for error in errors))
+
+        self.snapshot["plan"]["revision"] = "plan-v2"
+        self._write_snapshot()
+        self.assertEqual(CHECKER.validate(self.workspace), [])
+
     def test_deep_claim_in_quick_snapshot_fails(self) -> None:
         self.snapshot["source"]["reading"] = {"coveragePercent": 100, "blockedRanges": []}
         self._write_snapshot()
@@ -141,6 +171,44 @@ def test_published_lesson_index_passes(self) -> None:
         self._publish_lesson_index()
         self.assertEqual(CHECKER.validate(self.workspace), [])
 
+    def test_published_lesson_must_pass_chinese_grounding_gate(self) -> None:
+        self._publish_lesson_index()
+        (self.workspace / "lessons/0001-first.html").write_text(
+            "<html><body><h1>Generic lesson</h1></body></html>",
+            encoding="utf-8",
+        )
+        errors = CHECKER.validate(self.workspace)
+        self.assertTrue(any("html language must be zh-CN" in error for error in errors))
+        self.assertTrue(any("source-grounded evidence block" in error for error in errors))
+
+    def test_repeated_paragraphs_across_lessons_fail(self) -> None:
+        self._publish_lesson_index()
+        lessons = self.workspace / "lessons"
+        (lessons / "0002-second.html").write_text(
+            quality_lesson_html(marker="第二个状态判断"),
+            encoding="utf-8",
+        )
+        index_path = lessons / "index.json"
+        manifest = json.loads(index_path.read_text(encoding="utf-8"))
+        manifest["lessons"].append({
+            "order": 2,
+            "path": "lessons/0002-second.html",
+            "title": "第二个状态判断",
+            "status": "published",
+        })
+        index_path.write_text(json.dumps(manifest), encoding="utf-8")
+        self.snapshot["generation"]["publishedLessons"] = 2
+        self._write_snapshot()
+
+        errors = CHECKER.validate(self.workspace)
+        self.assertTrue(any("repeated learner-facing block" in error for error in errors))
+
+    def test_v2_profile_cannot_claim_v4_lesson_contract(self) -> None:
+        self.snapshot["profile"]["skill"]["contractRevision"] = "teach-quick-v2"
+        self._write_snapshot()
+        errors = CHECKER.validate(self.workspace)
+        self.assertTrue(any("quick profile pin is invalid" in error for error in errors))
+
     def test_published_lessons_require_index(self) -> None:
         self.snapshot["generation"] = {"status": "partially_ready", "publishedLessons": 1}
         self._write_snapshot()
diff --git a/apps/kimi-web/study-skills/teach-quick/tests/test_quick_lesson_revision.py b/apps/kimi-web/study-skills/teach-quick/tests/test_quick_lesson_revision.py
new file mode 100644
index 00000000..ece26031
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-quick/tests/test_quick_lesson_revision.py
@@ -0,0 +1,86 @@
+from __future__ import annotations
+
+import importlib.util
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+
+SKILL_ROOT = Path(__file__).resolve().parents[1]
+SCRIPTS = SKILL_ROOT / "scripts"
+sys.path.insert(0, str(SCRIPTS))
+
+MODULE_PATH = SCRIPTS / "lesson_revision.py"
+SPEC = importlib.util.spec_from_file_location("quick_lesson_revision", MODULE_PATH)
+REVISION = importlib.util.module_from_spec(SPEC)
+assert SPEC and SPEC.loader
+SPEC.loader.exec_module(REVISION)
+
+FIXTURE_PATH = Path(__file__).resolve().parent / "test_quick_gate.py"
+FIXTURE_SPEC = importlib.util.spec_from_file_location("quick_gate_fixture", FIXTURE_PATH)
+FIXTURE = importlib.util.module_from_spec(FIXTURE_SPEC)
+assert FIXTURE_SPEC and FIXTURE_SPEC.loader
+FIXTURE_SPEC.loader.exec_module(FIXTURE)
+
+
+class LessonRevisionTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self.temp = tempfile.TemporaryDirectory()
+        self.workspace = Path(self.temp.name)
+        (self.workspace / "lessons").mkdir()
+        (self.workspace / ".study-drafts").mkdir()
+        self.lesson = self.workspace / "lessons/0001-first.html"
+        self.other_lesson = self.workspace / "lessons/0002-second.html"
+        self.draft = self.workspace / ".study-drafts/0001-first.html"
+        self.original = FIXTURE.quality_lesson_html()
+        self.lesson.write_text(self.original, encoding="utf-8")
+        self.other_lesson.write_text("untouched sibling lesson", encoding="utf-8")
+
+    def tearDown(self) -> None:
+        self.temp.cleanup()
+
+    def publish(self, candidate: str, expected: str | None = None) -> str:
+        self.draft.write_text(candidate, encoding="utf-8")
+        return REVISION.publish_candidate(
+            self.workspace,
+            "lessons/0001-first.html",
+            ".study-drafts/0001-first.html",
+            expected or REVISION.lesson_revision(self.original),
+        )
+
+    def test_revision_matches_browser_utf8_fnv_contract(self) -> None:
+        self.assertEqual(REVISION.lesson_revision("<h1>第一课</h1>"), "fnv1a32:7735397a")
+
+    def test_guarded_publish_replaces_only_the_current_lesson(self) -> None:
+        candidate = self.original.replace(
+            "常见误区",
+            "容易踩坑的地方",
+        )
+        result = self.publish(candidate)
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), candidate)
+        self.assertEqual(
+            self.other_lesson.read_text(encoding="utf-8"),
+            "untouched sibling lesson",
+        )
+        self.assertEqual(result, REVISION.lesson_revision(candidate))
+        self.assertFalse(self.draft.exists())
+
+    def test_stale_base_keeps_the_published_lesson(self) -> None:
+        with self.assertRaisesRegex(ValueError, "stale lesson revision"):
+            self.publish(self.original, "fnv1a32:00000000")
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), self.original)
+
+    def test_changed_source_anchor_is_refused(self) -> None:
+        with self.assertRaisesRegex(ValueError, "source anchors"):
+            self.publish(FIXTURE.quality_lesson_html(anchor="伪造位置 §9"))
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), self.original)
+
+    def test_changed_title_is_refused(self) -> None:
+        with self.assertRaisesRegex(ValueError, "title"):
+            self.publish(FIXTURE.quality_lesson_html(marker="另一节课"))
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), self.original)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/apps/kimi-web/study-skills/teach-ria/CONTRACT.json b/apps/kimi-web/study-skills/teach-ria/CONTRACT.json
index 56328738..67f2280c 100644
--- a/apps/kimi-web/study-skills/teach-ria/CONTRACT.json
+++ b/apps/kimi-web/study-skills/teach-ria/CONTRACT.json
@@ -1,6 +1,6 @@
 {
   "name": "teach-ria",
-  "contractRevision": "teach-ria-v2",
+  "contractRevision": "teach-ria-v4",
   "productContractRevision": "kimi-study-foundation-v1",
   "upstream": {
     "repository": "https://github.com/Sebastianhayashi/skills",
diff --git a/apps/kimi-web/study-skills/teach-ria/LESSON-BRIEF-FORMAT.md b/apps/kimi-web/study-skills/teach-ria/LESSON-BRIEF-FORMAT.md
index bcde111b..d3eb5450 100644
--- a/apps/kimi-web/study-skills/teach-ria/LESSON-BRIEF-FORMAT.md
+++ b/apps/kimi-web/study-skills/teach-ria/LESSON-BRIEF-FORMAT.md
@@ -18,6 +18,9 @@ The brief is a source-grounded publication contract. It prevents a lesson from i
 ## Primary capability slice
 {One observable move the learner will understand or perform. Do not join adjacent slices.}
 
+## Learning objective
+{One learner-facing, observable capability that the self-check can actually test.}
+
 ## Source anchors
 - {source file, chapter, page or stable location, and source unit ID}
 - {additional exact location needed for the case or boundary}
@@ -28,6 +31,9 @@ The brief is a source-grounded publication contract. It prevents a lesson from i
 ## Core concept
 {The concept in the author's sense, including enough surrounding logic to avoid a slogan.}
 
+## Plain explanation
+{The difficult reasoning step rewritten in natural Chinese and explained progressively. Do not translate the source sentence by sentence.}
+
 ## Original source case
 {At least one complete case from the book. Name the actors, situation, decision, and outcome. A quotation or case name is not enough.}
 
@@ -45,6 +51,9 @@ The brief is a source-grounded publication contract. It prevents a lesson from i
 ## Boundary or misconception
 {A plausible misuse, overgeneralization, counterexample, or condition under which the concept changes.}
 
+## Lesson summary
+{The compact reasoning chain or decision rule the learner should retain. Do not write a generic recap.}
+
 ## Practice and feedback
 - Task:
 - Observable response:
@@ -61,6 +70,7 @@ The brief is a source-grounded publication contract. It prevents a lesson from i
 - [ ] I reopened and reread every source anchor above.
 - [ ] Every named RIA unit is verified, pressure-tested, and represented without losing its boundary.
 - [ ] The lesson teaches only the primary capability slice.
+- [ ] The learning objective is observable and the self-check directly tests it.
 - [ ] The original case retains the complete reasoning chain.
 - [ ] The transfer example is tied to the current mission.
 - [ ] Practice includes evaluation criteria and immediate feedback.
@@ -72,15 +82,24 @@ If the time budget cannot hold this brief, split the slice or create a continuat
 
 The matching HTML must include visible sections for every part of the contract:
 
+- `id="learning-objective"`
 - `id="core-concept"`
+- `id="plain-explanation"`
 - `id="ria-connection"`
 - `id="original-case"`
 - `id="reasoning-chain"`
 - `id="transfer-example"`
 - `id="boundary-misconception"`
+- `id="lesson-summary"`
 - `id="practice-feedback"`
 - `id="retrieval-connection"`
 - `id="explicit-exclusions"`
 - `id="source-anchors"`
 
 These IDs let the structural check verify that the brief reached the lesson. They do not replace the final semantic comparison against the reopened source.
+
+Source-grounded HTML blocks also use `data-evidence="source"` with an exact
+`data-source-anchor`; invented Mission transfers use
+`data-evidence="teaching-example"`. Follow
+[LESSON-QUALITY-FORMAT.md](./LESSON-QUALITY-FORMAT.md) for the complete Chinese
+writing and evidence-labelling contract.
diff --git a/apps/kimi-web/study-skills/teach-ria/LESSON-QUALITY-FORMAT.md b/apps/kimi-web/study-skills/teach-ria/LESSON-QUALITY-FORMAT.md
new file mode 100644
index 00000000..2a360cb5
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-ria/LESSON-QUALITY-FORMAT.md
@@ -0,0 +1,77 @@
+# Chinese lesson quality contract
+
+This contract applies to every published `lessons/*.html` file. It is a set of
+teaching and evidence obligations, not a prose template: section length,
+examples, and ordering should follow the source and the learner's Mission.
+
+## Learner-facing structure
+
+Use one `<h1>` and `<html lang="zh-CN">`. A lesson must make these moves visible:
+
+| Move | HTML id | Purpose |
+|---|---|---|
+| Learning objective | `learning-objective` | One observable capability, not “understand the chapter”. |
+| Core concept | `core-concept` | The source idea with its conditions and scope. |
+| Plain explanation | `plain-explanation` | Natural Chinese that explains the difficult step progressively. |
+| Source example | `source-example` or `original-case` | A traceable example actually supported by the material. |
+| Application example | `application-example` or `transfer-example` | A clearly labelled teaching example, never disguised as source fact. |
+| Misconception or boundary | `misconception` or `boundary-misconception` | A plausible misuse, counterexample, or limit. |
+| Lesson summary | `lesson-summary` | A compact decision rule or reasoning chain, not an AI-style recap. |
+| Self-check | `self-check` or `practice-feedback` | A task aligned to the objective plus answer logic or immediate feedback. |
+| Source anchors | `source-anchors` | Every stable source location used in the lesson. |
+
+Do not repeat a generic definition, welcome paragraph, motivational sentence,
+or identical summary across lessons. Retrieve prior knowledge only when it is
+needed for the current move.
+
+## Evidence labelling
+
+Wrap source-grounded claims or cases in a visible block with both attributes:
+
+```html
+<p data-evidence="source" data-source-anchor="第 2 节：状态指示灯">
+  材料中说明：蓝灯慢闪表示设备正在等待配对。
+</p>
+```
+
+The anchor must be a real, stable location reopened during authoring. Generic
+values such as `原文`, `材料`, or `参考资料` are invalid. List the same anchor
+verbatim in `source-anchors`.
+
+Wrap an invented teaching transfer separately:
+
+```html
+<p data-evidence="teaching-example">
+  教学示例：把指示灯当作排查入口。这个情境用于练习，不是材料中的真实案例。
+</p>
+```
+
+If the source cannot support a requested example or factual detail, say
+`资料中未找到可核验依据` and omit the claim. Never create a page number,
+quotation, actor, outcome, statistic, policy threshold, or technical behavior.
+
+## Chinese writing rules
+
+- Write idiomatic, compact Chinese; reorganize source syntax instead of
+  translating English sentence order.
+- Start from the learner's concrete difficulty. Avoid ceremonial introductions,
+  motivational filler, and “让我们开启学习之旅” language.
+- Explain one hard step at a time. Keep source facts, teaching examples, and
+  uncertainty visibly distinct.
+- Preserve the source's complete reasoning and boundary when compression would
+  turn it into a slogan.
+- Use examples only when they expose the concept or decision rule.
+- Make self-check feedback explain why an answer succeeds or fails.
+
+## Publication gate
+
+Before adding a lesson to `lessons/index.json`:
+
+1. reopen every named source anchor;
+2. compare every source-labelled claim against that location;
+3. run the course checker, which applies `scripts/lesson_quality.py`;
+4. compare published lessons for repeated learner-facing paragraphs;
+5. publish the HTML, lesson index, and snapshot in the documented atomic order.
+
+Structural checks cannot prove factual truth. Passing them is permission to
+publish only after the semantic source comparison above is complete.
diff --git a/apps/kimi-web/study-skills/teach-ria/LESSON-REVISION-FORMAT.md b/apps/kimi-web/study-skills/teach-ria/LESSON-REVISION-FORMAT.md
new file mode 100644
index 00000000..300eff1b
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-ria/LESSON-REVISION-FORMAT.md
@@ -0,0 +1,38 @@
+# Current lesson revision workflow
+
+Kimi Study may ask this Skill to revise or regenerate exactly one published lesson. The request supplies a course id, a `lessons/<safe-name>.html` path, a base content revision, and an operation id. A revision request also supplies one learner instruction.
+
+## Non-negotiable boundaries
+
+- Inspect the current lesson, `lessons/index.json`, the approved plan, and its cited source ranges before drafting.
+- Keep the course id, lesson path, indexed title, plan revision, publication status, generation counts, and every other lesson unchanged.
+- Preserve the exact existing `data-source-anchor` set. Reopen those source locations and keep source facts distinct from teaching examples.
+- Never write directly over the published lesson while drafting. Use `.study-drafts/<same-file-name>.html`.
+- A stale base revision, missing source, invalid candidate, changed title, or changed anchor set is a hard stop. Leave the published lesson untouched and report the reason.
+
+## Guarded publication
+
+1. Confirm the current identity before work begins:
+
+   ```bash
+   python3 scripts/lesson_revision.py \
+     --workspace "$PWD" \
+     --lesson lessons/0001-example.html \
+     --expect fnv1a32:12345678
+   ```
+
+2. Draft only `.study-drafts/0001-example.html`. For a revision, apply the learner's instruction without unrelated rewrites. For regeneration, rebuild the explanation and examples while retaining the same learning objective, title, and source anchors.
+3. Validate the draft with the mode's lesson checker. Run the full course checker too, so cross-lesson repetition and publication invariants still pass.
+4. Immediately before replacement, atomically publish through the guard:
+
+   ```bash
+   python3 scripts/lesson_revision.py \
+     --workspace "$PWD" \
+     --lesson lessons/0001-example.html \
+     --expect fnv1a32:12345678 \
+     --candidate .study-drafts/0001-example.html
+   ```
+
+5. Run the full checker again. Do not change `source/STUDY-SNAPSHOT.json` merely to signal success: the published lesson content is the authoritative revision, and the existing lesson index remains valid because identity and status did not change.
+
+The revision token is FNV-1a over UTF-8 bytes, formatted as `fnv1a32:` plus eight lowercase hexadecimal digits. It is a stale-write identity, not a cryptographic claim.
diff --git a/apps/kimi-web/study-skills/teach-ria/SKILL.md b/apps/kimi-web/study-skills/teach-ria/SKILL.md
index c44bd05c..efbdd786 100644
--- a/apps/kimi-web/study-skills/teach-ria/SKILL.md
+++ b/apps/kimi-web/study-skills/teach-ria/SKILL.md
@@ -1,6 +1,6 @@
 ---
 name: teach-ria
-description: "[contract:teach-ria-v2] Read an uploaded textbook or nonfiction source in full, distill it through verified RIA++ method units while interviewing the learner's Mission, and build a source-faithful course. Use for Kimi Study deep mode, upgrades from quick mode, and certified preprocessed textbook packages."
+description: "[contract:teach-ria-v4] Read an uploaded textbook or nonfiction source in full, distill it through verified RIA++ method units while interviewing the learner's Mission, and build a source-faithful Chinese course. Use for Kimi Study deep mode, upgrades from quick mode, and certified preprocessed textbook packages."
 ---
 
 # Teach RIA
@@ -28,7 +28,7 @@ Maintain these artifacts as relevant:
 - `source/TEACHING-MAP.md`: ordered mission-bound slices.
 - `source/lesson-briefs/*.md`: source-grounded publication contracts. Follow [LESSON-BRIEF-FORMAT.md](./LESSON-BRIEF-FORMAT.md).
 - `source/STUDY-PACKAGE.json`: immutable source-only manifest when preparing a catalog textbook. Follow [CATALOG-PACKAGE-FORMAT.md](./CATALOG-PACKAGE-FORMAT.md).
-- `lessons/*.html` and `lessons/index.json` (follow [LESSON-INDEX-FORMAT.md](./LESSON-INDEX-FORMAT.md)), plus `reference/*.html`, `learning-records/*.md`, `RESOURCES.md`, `assets/*`, and `NOTES.md`.
+- `lessons/*.html` and `lessons/index.json` (follow [LESSON-QUALITY-FORMAT.md](./LESSON-QUALITY-FORMAT.md), [LESSON-REVISION-FORMAT.md](./LESSON-REVISION-FORMAT.md), and [LESSON-INDEX-FORMAT.md](./LESSON-INDEX-FORMAT.md)), plus `reference/*.html`, `learning-records/*.md`, `RESOURCES.md`, `assets/*`, and `NOTES.md`.
 
 Inspect current artifacts before acting. A valid source-bound reading/RIA revision survives a Mission change; mission-bound blueprint, map, and unpublished briefs do not.
 
@@ -117,19 +117,28 @@ Only respond to generation requests that name the exact approved plan revision.
 
 Before each book-derived lesson:
 
-1. create `source/lesson-briefs/NNNN-name.md` from the next unconsumed teaching-map slice;
-2. reopen every original source anchor named in the brief;
-3. run `python3 scripts/check-book-course.py --workspace /absolute/workspace --brief source/lesson-briefs/NNNN-name.md`;
-4. create `lessons/NNNN-name.html` only after the brief passes;
-5. compare the lesson line by line with the brief and reopened source;
-6. mark the brief published and run the checker with `--lesson`;
-7. atomically update `lessons/index.json` with the lesson title, order, and `published` status;
-8. set `publishedLessons` to the manifest's published count and publish incrementally in the Study snapshot.
+1. read [LESSON-QUALITY-FORMAT.md](./LESSON-QUALITY-FORMAT.md) before the first lesson in this generation run;
+2. create `source/lesson-briefs/NNNN-name.md` from the next unconsumed teaching-map slice;
+3. reopen every original source anchor named in the brief;
+4. run `python3 scripts/check-book-course.py --workspace /absolute/workspace --brief source/lesson-briefs/NNNN-name.md`;
+5. create `lessons/NNNN-name.html` only after the brief passes;
+6. compare the lesson line by line with the brief and reopened source;
+7. mark the brief published and run the checker with `--lesson`;
+8. atomically update `lessons/index.json` with the lesson title, order, and `published` status;
+9. set `publishedLessons` to the manifest's published count, run the full checker to catch repetition and publication drift, and publish incrementally in the Study snapshot.
 
-Each lesson teaches one primary capability slice, retains a complete original case and reasoning chain, transfers it to the Mission, shows a boundary or misconception, includes practice with immediate feedback, cites stable source locations, and connects retrieval across lessons.
+Each lesson teaches one primary capability slice in natural Chinese, retains a complete original case and reasoning chain, explains the difficult step progressively, transfers it to the Mission, shows a boundary or misconception, includes an objective-aligned self-check with immediate feedback, cites stable source locations, and connects retrieval across lessons. Mark source-grounded blocks with exact source anchors and mark invented teaching transfers separately; never let a fresh example masquerade as a book case. Do not reuse generic definitions, introductions, or summaries across lessons.
 
 Reuse assets and build durable reference material. Treat parametric knowledge as untrusted; use high-trust external sources only to correct, update, or clarify the supplied source.
 
+## Current-lesson revision and regeneration
+
+When Kimi Study names an exact published lesson path, base content revision, and operation id, read [LESSON-REVISION-FORMAT.md](./LESSON-REVISION-FORMAT.md) before acting. Reopen the lesson brief and every cited original-source anchor. Reject a stale base. Draft and validate only `.study-drafts/<same-file-name>.html`, preserve the indexed title and exact anchor set, run both the lesson and full-course fidelity gates, then publish through `scripts/lesson_revision.py`. Do not change the course, blueprint, teaching map, generation counts, or another lesson. A failed check leaves the published lesson unchanged.
+
+## Upgrade from an existing quick course
+
+An upgrade reuses the same course workspace, source identity, and session. Inspect the existing Quick survey, plan, lesson index, and published lesson files before deep work starts. Never delete or overwrite a completed lesson during reading, distillation, or blueprint design. A Quick lesson may be adopted or replaced only after its Deep brief, reopened-source, Chinese quality, and publication gates pass; until then it remains the last valid rollback artifact. Do not create a second course directory or reset unrelated learning records.
+
 ## Failure and repair
 
 When blocked, update the Study snapshot with the exact source, Mission, plan, or generation blocker. Do not generate a provisional lesson.
diff --git a/apps/kimi-web/study-skills/teach-ria/STUDY-SNAPSHOT-FORMAT.md b/apps/kimi-web/study-skills/teach-ria/STUDY-SNAPSHOT-FORMAT.md
index cc5b1129..dbab807f 100644
--- a/apps/kimi-web/study-skills/teach-ria/STUDY-SNAPSHOT-FORMAT.md
+++ b/apps/kimi-web/study-skills/teach-ria/STUDY-SNAPSHOT-FORMAT.md
@@ -11,7 +11,7 @@ Required identity for a fresh upload:
   "courseId": "course-from-activation-args",
   "profile": {
     "mode": "deep",
-    "skill": { "name": "teach-ria", "contractRevision": "teach-ria-v2" },
+    "skill": { "name": "teach-ria", "contractRevision": "teach-ria-v4" },
     "sourceRevision": "exact-source-revision",
     "selectedBy": "user"
   }
diff --git a/apps/kimi-web/study-skills/teach-ria/scripts/check-book-course.py b/apps/kimi-web/study-skills/teach-ria/scripts/check-book-course.py
index c1c6bfa1..960be2c0 100644
--- a/apps/kimi-web/study-skills/teach-ria/scripts/check-book-course.py
+++ b/apps/kimi-web/study-skills/teach-ria/scripts/check-book-course.py
@@ -11,29 +11,38 @@
 import sys
 from pathlib import Path
 
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+from lesson_quality import find_repeated_blocks, validate_lesson_html
+
 
 PLACEHOLDER = re.compile(r"\{[^}]*\}|\b(?:TBD|TODO)\b", re.IGNORECASE)
 BRIEF_SECTIONS = (
     "Primary capability slice",
+    "Learning objective",
     "Source anchors",
     "RIA grounding",
     "Core concept",
+    "Plain explanation",
     "Original source case",
     "Reasoning chain",
     "Transfer example",
     "Boundary or misconception",
+    "Lesson summary",
     "Practice and feedback",
     "Retrieval connection",
     "Explicit exclusions",
     "Publication check",
 )
 HTML_SECTIONS = (
+    "learning-objective",
     "core-concept",
+    "plain-explanation",
     "ria-connection",
     "original-case",
     "reasoning-chain",
     "transfer-example",
     "boundary-misconception",
+    "lesson-summary",
     "practice-feedback",
     "retrieval-connection",
     "explicit-exclusions",
@@ -562,7 +571,7 @@ def validate_brief(
         if not non_placeholder(field(practice, label)):
             errors.append(f"{brief}: Practice and feedback is missing {label}")
 
-    checked_audit(source, "Publication check", 7, errors)
+    checked_audit(source, "Publication check", 9, errors)
 
     if lesson_value:
         lesson_path = resolve_workspace_path(workspace, lesson_value)
@@ -669,6 +678,7 @@ def validate_lesson_index(workspace: Path, generation: dict, errors: list[str])
         return
 
     seen_paths: set[str] = set()
+    published_documents: dict[str, str] = {}
     published_count = 0
     all_published = True
     for index, lesson in enumerate(lessons, start=1):
@@ -694,8 +704,14 @@ def validate_lesson_index(workspace: Path, generation: dict, errors: list[str])
             all_published = False
         elif status == "published":
             published_count += 1
-            if isinstance(path, str) and not (workspace / path).is_file():
-                errors.append(f"lessons/index.json: published lesson is missing: {path}")
+            if isinstance(path, str):
+                lesson_path = workspace / path
+                if not lesson_path.is_file():
+                    errors.append(f"lessons/index.json: published lesson is missing: {path}")
+                elif re.fullmatch(r"lessons/[A-Za-z0-9][A-Za-z0-9._-]*\.html", path):
+                    lesson_source = read_text(lesson_path)
+                    published_documents[path] = lesson_source
+                    errors.extend(validate_lesson_html(lesson_source, path))
         else:
             all_published = False
 
@@ -703,6 +719,10 @@ def validate_lesson_index(workspace: Path, generation: dict, errors: list[str])
         errors.append("lessons/index.json: published count does not match STUDY-SNAPSHOT.json")
     if generation.get("status") == "ready" and not all_published:
         errors.append("lessons/index.json: ready generation requires every lesson to be published")
+    errors.extend(
+        f"lessons/index.json: {error}"
+        for error in find_repeated_blocks(published_documents)
+    )
 
 
 def validate_study_snapshot(workspace: Path, errors: list[str]) -> None:
@@ -734,7 +754,7 @@ def validate_study_snapshot(workspace: Path, errors: list[str]) -> None:
     mode = profile.get("mode")
     if mode not in {"deep", "deep_preprocessed"}:
         errors.append("STUDY-SNAPSHOT.json: deep profile mode is invalid")
-    if profile.get("skill") != {"name": "teach-ria", "contractRevision": "teach-ria-v2"}:
+    if profile.get("skill") != {"name": "teach-ria", "contractRevision": "teach-ria-v4"}:
         errors.append("STUDY-SNAPSHOT.json: teach-ria Skill pin is invalid")
     if profile.get("sourceRevision") != source.get("revision"):
         errors.append("STUDY-SNAPSHOT.json: profile and source revisions differ")
@@ -822,18 +842,29 @@ def main() -> int:
         )
     elif args.lesson:
         lesson = resolve_workspace_path(workspace, str(args.lesson))
-        brief = source_dir / "lesson-briefs" / f"{lesson.stem}.md"
-        validate_brief(
-            workspace,
-            brief,
-            mission_hash,
-            revision,
-            slice_ids,
-            map_slice_order,
-            ria_unit_ids,
-            errors,
-        )
-        validate_lesson(workspace, lesson, brief, errors)
+        try:
+            relative = lesson.relative_to(workspace).as_posix()
+        except ValueError:
+            errors.append("candidate lesson must stay inside the course workspace")
+        else:
+            if not re.fullmatch(
+                r"(?:lessons|\.study-drafts)/[A-Za-z0-9][A-Za-z0-9._-]*\.html",
+                relative,
+            ):
+                errors.append("candidate lesson path is unsafe")
+            else:
+                brief = source_dir / "lesson-briefs" / f"{lesson.stem}.md"
+                validate_brief(
+                    workspace,
+                    brief,
+                    mission_hash,
+                    revision,
+                    slice_ids,
+                    map_slice_order,
+                    ria_unit_ids,
+                    errors,
+                )
+                validate_lesson(workspace, lesson, brief, errors)
 
     if errors:
         print("Book-course fidelity check failed:", file=sys.stderr)
diff --git a/apps/kimi-web/study-skills/teach-ria/scripts/lesson_quality.py b/apps/kimi-web/study-skills/teach-ria/scripts/lesson_quality.py
new file mode 100644
index 00000000..da2c86ad
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-ria/scripts/lesson_quality.py
@@ -0,0 +1,185 @@
+#!/usr/bin/env python3
+"""Deterministic structural gates for learner-facing Chinese lesson HTML."""
+
+from __future__ import annotations
+
+import html
+import re
+from collections import defaultdict
+
+
+SECTION_GROUPS: dict[str, tuple[str, ...]] = {
+    "learning-objective": ("learning-objective",),
+    "core-concept": ("core-concept",),
+    "plain-explanation": ("plain-explanation",),
+    "source-example": ("source-example", "original-case"),
+    "application-example": ("application-example", "transfer-example"),
+    "misconception": ("misconception", "boundary-misconception"),
+    "lesson-summary": ("lesson-summary",),
+    "self-check": ("self-check", "practice-feedback"),
+    "source-anchors": ("source-anchors",),
+}
+
+AI_FILLER_PATTERNS = tuple(
+    re.compile(pattern)
+    for pattern in (
+        r"在当今快速发展的时代",
+        r"让我们(?:一起|来)(?:深入|共同)?(?:探索|学习|开启)",
+        r"开启.{0,12}(?:学习|知识)之旅",
+        r"(?:综上所述|总而言之)",
+        r"不难发现",
+        r"至关重要",
+    )
+)
+
+GENERIC_ANCHORS = {"原文", "材料", "资料", "来源", "见原文", "参考资料"}
+ATTRIBUTE_RE = re.compile(
+    r"(?P<name>[a-zA-Z_:][-a-zA-Z0-9_:.]*)\s*=\s*(?P<quote>['\"])(?P<value>.*?)(?P=quote)",
+    re.DOTALL,
+)
+
+
+def _attributes(fragment: str) -> dict[str, str]:
+    return {
+        match.group("name").lower(): html.unescape(match.group("value")).strip()
+        for match in ATTRIBUTE_RE.finditer(fragment)
+    }
+
+
+def _visible_text(source: str) -> str:
+    cleaned = re.sub(r"<!--.*?-->", " ", source, flags=re.DOTALL)
+    cleaned = re.sub(r"<(?:script|style)\b.*?</(?:script|style)\s*>", " ", cleaned, flags=re.I | re.S)
+    cleaned = re.sub(r"<[^>]+>", " ", cleaned)
+    return re.sub(r"\s+", " ", html.unescape(cleaned)).strip()
+
+
+def _section(source: str, section_id: str) -> tuple[int, str]:
+    match = re.search(
+        rf"<(?P<tag>[a-z][\w:-]*)\b[^>]*\bid=['\"]{re.escape(section_id)}['\"][^>]*>"
+        rf"(?P<body>.*?)</(?P=tag)\s*>",
+        source,
+        re.IGNORECASE | re.DOTALL,
+    )
+    if match is None:
+        return (-1, "")
+    return (match.start(), _visible_text(match.group("body")))
+
+
+def _evidence_elements(source: str) -> list[dict[str, str]]:
+    elements: list[dict[str, str]] = []
+    pattern = re.compile(
+        r"<(?P<tag>[a-z][\w:-]*)\b(?P<attrs>[^>]*\bdata-evidence\s*=\s*['\"][^'\"]+['\"][^>]*)>"
+        r"(?P<body>.*?)</(?P=tag)\s*>",
+        re.IGNORECASE | re.DOTALL,
+    )
+    for match in pattern.finditer(source):
+        attrs = _attributes(match.group("attrs"))
+        elements.append({
+            "kind": attrs.get("data-evidence", ""),
+            "anchor": attrs.get("data-source-anchor", ""),
+            "text": _visible_text(match.group("body")),
+        })
+    return elements
+
+
+def inspect_lesson_html(source: str) -> dict[str, object]:
+    sections: dict[str, str] = {}
+    positions: dict[str, int] = {}
+    for canonical, aliases in SECTION_GROUPS.items():
+        candidates = [(_section(source, alias), alias) for alias in aliases]
+        present = [(position, text, alias) for (position, text), alias in candidates if position >= 0]
+        if present:
+            position, text, _ = min(present, key=lambda item: item[0])
+            positions[canonical] = position
+            sections[canonical] = text
+        else:
+            positions[canonical] = -1
+            sections[canonical] = ""
+
+    evidence = _evidence_elements(source)
+    source_evidence = [item for item in evidence if item["kind"] == "source"]
+    teaching_examples = [item for item in evidence if item["kind"] == "teaching-example"]
+    anchors = [item["anchor"] for item in source_evidence if item["anchor"]]
+    visible = _visible_text(source)
+    cjk_count = len(re.findall(r"[\u3400-\u9fff]", visible))
+    readable_count = len(re.findall(r"[\w\u3400-\u9fff]", visible))
+
+    blocks: list[str] = []
+    for match in re.finditer(r"<(?:p|li)\b[^>]*>(.*?)</(?:p|li)\s*>", source, re.I | re.S):
+        block = _visible_text(match.group(1))
+        if len(block) >= 40:
+            blocks.append(block)
+
+    return {
+        "sections": sections,
+        "positions": positions,
+        "sourceEvidence": source_evidence,
+        "teachingExamples": teaching_examples,
+        "anchors": anchors,
+        "visibleText": visible,
+        "cjkCount": cjk_count,
+        "cjkRatio": cjk_count / max(readable_count, 1),
+        "blocks": blocks,
+    }
+
+
+def validate_lesson_html(source: str, label: str = "lesson") -> list[str]:
+    errors: list[str] = []
+    report = inspect_lesson_html(source)
+    sections = report["sections"]
+    assert isinstance(sections, dict)
+
+    if not re.search(r"<html\b[^>]*\blang=['\"]zh(?:-CN)?['\"]", source, re.I):
+        errors.append(f"{label}: html language must be zh-CN")
+    if len(re.findall(r"<h1\b", source, re.I)) != 1:
+        errors.append(f"{label}: exactly one visible h1 is required")
+    for canonical in SECTION_GROUPS:
+        text = str(sections.get(canonical, ""))
+        if not text:
+            errors.append(f"{label}: missing lesson quality section {canonical}")
+        elif len(text) < 16:
+            errors.append(f"{label}: lesson quality section {canonical} is too thin")
+
+    if int(report["cjkCount"]) < 120 or float(report["cjkRatio"]) < 0.45:
+        errors.append(f"{label}: learner-facing content is not substantial natural Chinese")
+
+    visible = str(report["visibleText"])
+    for pattern in AI_FILLER_PATTERNS:
+        if pattern.search(visible):
+            errors.append(f"{label}: contains generic AI-style filler matched by {pattern.pattern}")
+
+    source_evidence = report["sourceEvidence"]
+    teaching_examples = report["teachingExamples"]
+    assert isinstance(source_evidence, list) and isinstance(teaching_examples, list)
+    if not source_evidence:
+        errors.append(f"{label}: requires at least one source-grounded evidence block")
+    if not teaching_examples:
+        errors.append(f"{label}: requires a teaching example explicitly separated from source facts")
+
+    anchor_section = str(sections.get("source-anchors", ""))
+    for item in source_evidence:
+        anchor = str(item.get("anchor", "")).strip()
+        if not anchor or anchor in GENERIC_ANCHORS or "{" in anchor or "TODO" in anchor.upper():
+            errors.append(f"{label}: source evidence has a missing or unstable anchor")
+        elif anchor not in anchor_section:
+            errors.append(f"{label}: source anchor {anchor!r} is absent from source-anchors")
+
+    positions = report["positions"]
+    assert isinstance(positions, dict)
+    quick_order = [positions[key] for key in SECTION_GROUPS if int(positions[key]) >= 0]
+    if quick_order != sorted(quick_order):
+        errors.append(f"{label}: lesson quality sections are not in a coherent learning order")
+    return errors
+
+
+def find_repeated_blocks(documents: dict[str, str]) -> list[str]:
+    owners: dict[str, set[str]] = defaultdict(set)
+    for label, source in documents.items():
+        report = inspect_lesson_html(source)
+        for block in report["blocks"]:
+            owners[re.sub(r"\s+", " ", str(block)).strip()].add(label)
+    return [
+        f"repeated learner-facing block across {', '.join(sorted(labels))}: {block[:80]}"
+        for block, labels in sorted(owners.items())
+        if len(labels) > 1
+    ]
diff --git a/apps/kimi-web/study-skills/teach-ria/scripts/lesson_revision.py b/apps/kimi-web/study-skills/teach-ria/scripts/lesson_revision.py
new file mode 100644
index 00000000..c14d48e1
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-ria/scripts/lesson_revision.py
@@ -0,0 +1,123 @@
+#!/usr/bin/env python3
+"""Guard and atomically publish one Kimi Study lesson revision."""
+
+from __future__ import annotations
+
+import argparse
+import html
+import os
+import re
+import sys
+from pathlib import Path
+
+from lesson_quality import inspect_lesson_html, validate_lesson_html
+
+
+LESSON_PATH = re.compile(r"lessons/[A-Za-z0-9][A-Za-z0-9._-]*\.html")
+DRAFT_PATH = re.compile(r"\.study-drafts/[A-Za-z0-9][A-Za-z0-9._-]*\.html")
+REVISION = re.compile(r"fnv1a32:[0-9a-f]{8}")
+
+
+def lesson_revision(source: str) -> str:
+    value = 0x811C9DC5
+    for byte in source.encode("utf-8"):
+        value ^= byte
+        value = (value * 0x01000193) & 0xFFFFFFFF
+    return f"fnv1a32:{value:08x}"
+
+
+def read_text(path: Path) -> str:
+    return path.read_text(encoding="utf-8")
+
+
+def visible_title(source: str) -> str:
+    match = re.search(r"<title>(.*?)</title>", source, re.I | re.S)
+    if match is None:
+        match = re.search(r"<h1\b[^>]*>(.*?)</h1\s*>", source, re.I | re.S)
+    if match is None:
+        return ""
+    return re.sub(r"\s+", " ", html.unescape(re.sub(r"<[^>]+>", " ", match.group(1)))).strip()
+
+
+def workspace_path(workspace: Path, value: str, pattern: re.Pattern[str]) -> Path:
+    workspace = workspace.resolve()
+    if pattern.fullmatch(value) is None:
+        raise ValueError(f"unsafe lesson revision path: {value}")
+    resolved = (workspace / value).resolve()
+    try:
+        resolved.relative_to(workspace)
+    except ValueError as error:
+        raise ValueError(f"lesson revision path leaves workspace: {value}") from error
+    return resolved
+
+
+def assert_revision(target: Path, expected: str) -> str:
+    if REVISION.fullmatch(expected) is None:
+        raise ValueError("expected lesson revision is malformed")
+    current = lesson_revision(read_text(target))
+    if current != expected:
+        raise ValueError(f"stale lesson revision: expected {expected}, found {current}")
+    return current
+
+
+def publish_candidate(workspace: Path, lesson: str, candidate: str, expected: str) -> str:
+    target = workspace_path(workspace, lesson, LESSON_PATH)
+    draft = workspace_path(workspace, candidate, DRAFT_PATH)
+    if target.name != draft.name:
+        raise ValueError("candidate filename must preserve lesson identity")
+    assert_revision(target, expected)
+
+    current_source = read_text(target)
+    candidate_source = read_text(draft)
+    errors = validate_lesson_html(candidate_source, lesson)
+    if errors:
+        raise ValueError(f"candidate lesson failed quality gates: {errors[0]}")
+    if visible_title(candidate_source) != visible_title(current_source):
+        raise ValueError("candidate lesson title must match the published lesson")
+
+    current_anchors = set(inspect_lesson_html(current_source)["anchors"])
+    candidate_anchors = set(inspect_lesson_html(candidate_source)["anchors"])
+    if candidate_anchors != current_anchors:
+        raise ValueError("candidate source anchors must exactly match the published lesson")
+
+    # Re-check immediately before replace; another operation may have won
+    # while the candidate was being validated.
+    assert_revision(target, expected)
+    with draft.open("rb") as handle:
+        os.fsync(handle.fileno())
+    os.replace(draft, target)
+    directory = os.open(target.parent, os.O_RDONLY)
+    try:
+        os.fsync(directory)
+    finally:
+        os.close(directory)
+    return lesson_revision(read_text(target))
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--workspace", type=Path, default=Path.cwd())
+    parser.add_argument("--lesson", required=True)
+    parser.add_argument("--expect")
+    parser.add_argument("--candidate")
+    args = parser.parse_args()
+    workspace = args.workspace.expanduser().resolve()
+    try:
+        target = workspace_path(workspace, args.lesson, LESSON_PATH)
+        if args.candidate is None:
+            revision = lesson_revision(read_text(target))
+            if args.expect is not None:
+                assert_revision(target, args.expect)
+        else:
+            if args.expect is None:
+                raise ValueError("--candidate requires --expect")
+            revision = publish_candidate(workspace, args.lesson, args.candidate, args.expect)
+    except (OSError, UnicodeError, ValueError) as error:
+        print(f"Lesson revision refused: {error}", file=sys.stderr)
+        return 1
+    print(revision)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/apps/kimi-web/study-skills/teach-ria/tests/test_ria_gate.py b/apps/kimi-web/study-skills/teach-ria/tests/test_ria_gate.py
index 6d3b7a96..13d61f9f 100644
--- a/apps/kimi-web/study-skills/teach-ria/tests/test_ria_gate.py
+++ b/apps/kimi-web/study-skills/teach-ria/tests/test_ria_gate.py
@@ -14,6 +14,22 @@
 SPEC.loader.exec_module(CHECKER)
 
 
+def quality_lesson_html(anchor: str = "测试材料 §1") -> str:
+    return f"""<!doctype html>
+<html lang="zh-CN"><body>
+<h1>根据证据完成一次判断</h1>
+<section id="learning-objective"><h2>学习目标</h2><p>完成本节后，你能依据材料中的信号和限制条件作出判断，并用一条完整推理链说明选择。</p></section>
+<section id="core-concept"><h2>核心概念</h2><p>可靠判断要把可观察信号、适用条件和允许动作连接起来，不能只记住脱离边界的一句结论。</p></section>
+<section id="plain-explanation"><h2>通俗解释</h2><p>先描述事实，再核对材料给出的条件，最后选择动作；任何一步缺少依据，都应该停下补证据。</p></section>
+<section id="source-example"><h2>材料中的例子</h2><p data-evidence="source" data-source-anchor="{anchor}">材料中说明：出现测试信号后，应先核对限制条件，再决定继续、等待或停止，不能跳过条件直接行动。</p></section>
+<section id="application-example"><h2>教学示例</h2><p data-evidence="teaching-example">教学示例：把新情境代入“信号—条件—动作”三步法。这个情境用于练习，不是材料中的真实案例。</p></section>
+<section id="misconception"><h2>常见误区</h2><p>凭经验看到信号就行动会忽略边界；当条件变化时，相同信号可能对应不同处理方式。</p></section>
+<section id="lesson-summary"><h2>本节总结</h2><p>记住这条规则：描述信号，核对条件，再采取材料允许的动作；没有依据时明确暂停。</p></section>
+<section id="self-check"><h2>自测题</h2><p>请判断只有信号时能否行动。答案是不能；合格回答要指出缺少的条件以及下一步核对位置。</p></section>
+<section id="source-anchors"><h2>材料依据</h2><p>{anchor}：本节关于信号、条件和动作顺序的直接依据，发布前已重新核对。</p></section>
+</body></html>"""
+
+
 class RiaGateTest(unittest.TestCase):
     def setUp(self) -> None:
         self.temporary_directory = tempfile.TemporaryDirectory()
@@ -190,7 +206,7 @@ def setUp(self) -> None:
             "courseId": "course-12345678",
             "profile": {
                 "mode": "deep",
-                "skill": {"name": "teach-ria", "contractRevision": "teach-ria-v2"},
+                "skill": {"name": "teach-ria", "contractRevision": "teach-ria-v4"},
                 "sourceRevision": "file:file-1",
                 "selectedBy": "user",
             },
@@ -245,7 +261,7 @@ def _write(self) -> None:
     def _publish_lesson_index(self, *, status: str = "partially_ready") -> None:
         lessons = self.workspace / "lessons"
         lessons.mkdir(exist_ok=True)
-        (lessons / "0001-first.html").write_text("<h1>First lesson</h1>", encoding="utf-8")
+        (lessons / "0001-first.html").write_text(quality_lesson_html(), encoding="utf-8")
         (lessons / "index.json").write_text(
             json.dumps(
                 {
@@ -255,7 +271,7 @@ def _publish_lesson_index(self, *, status: str = "partially_ready") -> None:
                         {
                             "order": 1,
                             "path": "lessons/0001-first.html",
-                            "title": "First lesson",
+                            "title": "根据证据完成一次判断",
                             "status": "published",
                         }
                     ],
@@ -288,6 +304,24 @@ def test_published_lesson_index_passes(self) -> None:
         CHECKER.validate_study_snapshot(self.workspace, errors)
         self.assertEqual(errors, [])
 
+    def test_published_lesson_must_pass_chinese_grounding_gate(self) -> None:
+        self._publish_lesson_index()
+        (self.workspace / "lessons/0001-first.html").write_text(
+            "<html><body><h1>Generic lesson</h1></body></html>",
+            encoding="utf-8",
+        )
+        errors: list[str] = []
+        CHECKER.validate_study_snapshot(self.workspace, errors)
+        self.assertTrue(any("html language must be zh-CN" in error for error in errors))
+        self.assertTrue(any("source-grounded evidence block" in error for error in errors))
+
+    def test_v2_profile_cannot_claim_v4_lesson_contract(self) -> None:
+        self.snapshot["profile"]["skill"]["contractRevision"] = "teach-ria-v2"
+        self._write()
+        errors: list[str] = []
+        CHECKER.validate_study_snapshot(self.workspace, errors)
+        self.assertTrue(any("Skill pin is invalid" in error for error in errors))
+
     def test_published_lessons_require_index(self) -> None:
         self.snapshot["generation"] = {
             "status": "partially_ready",
diff --git a/apps/kimi-web/study-skills/teach-ria/tests/test_ria_lesson_revision.py b/apps/kimi-web/study-skills/teach-ria/tests/test_ria_lesson_revision.py
new file mode 100644
index 00000000..3dc4f893
--- /dev/null
+++ b/apps/kimi-web/study-skills/teach-ria/tests/test_ria_lesson_revision.py
@@ -0,0 +1,89 @@
+from __future__ import annotations
+
+import importlib.util
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+
+SKILL_ROOT = Path(__file__).resolve().parents[1]
+SCRIPTS = SKILL_ROOT / "scripts"
+sys.path.insert(0, str(SCRIPTS))
+
+MODULE_PATH = SCRIPTS / "lesson_revision.py"
+SPEC = importlib.util.spec_from_file_location("ria_lesson_revision", MODULE_PATH)
+REVISION = importlib.util.module_from_spec(SPEC)
+assert SPEC and SPEC.loader
+SPEC.loader.exec_module(REVISION)
+
+FIXTURE_PATH = Path(__file__).resolve().parent / "test_ria_gate.py"
+FIXTURE_SPEC = importlib.util.spec_from_file_location("ria_gate_fixture", FIXTURE_PATH)
+FIXTURE = importlib.util.module_from_spec(FIXTURE_SPEC)
+assert FIXTURE_SPEC and FIXTURE_SPEC.loader
+FIXTURE_SPEC.loader.exec_module(FIXTURE)
+
+
+class LessonRevisionTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self.temp = tempfile.TemporaryDirectory()
+        self.workspace = Path(self.temp.name)
+        (self.workspace / "lessons").mkdir()
+        (self.workspace / ".study-drafts").mkdir()
+        self.lesson = self.workspace / "lessons/0001-first.html"
+        self.other_lesson = self.workspace / "lessons/0002-second.html"
+        self.draft = self.workspace / ".study-drafts/0001-first.html"
+        self.original = FIXTURE.quality_lesson_html()
+        self.lesson.write_text(self.original, encoding="utf-8")
+        self.other_lesson.write_text("untouched sibling lesson", encoding="utf-8")
+
+    def tearDown(self) -> None:
+        self.temp.cleanup()
+
+    def publish(self, candidate: str, expected: str | None = None) -> str:
+        self.draft.write_text(candidate, encoding="utf-8")
+        return REVISION.publish_candidate(
+            self.workspace,
+            "lessons/0001-first.html",
+            ".study-drafts/0001-first.html",
+            expected or REVISION.lesson_revision(self.original),
+        )
+
+    def test_revision_matches_browser_utf8_fnv_contract(self) -> None:
+        self.assertEqual(REVISION.lesson_revision("<h1>第一课</h1>"), "fnv1a32:7735397a")
+
+    def test_guarded_publish_replaces_only_the_current_lesson(self) -> None:
+        candidate = self.original.replace(
+            "常见误区",
+            "容易踩坑的地方",
+        )
+        result = self.publish(candidate)
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), candidate)
+        self.assertEqual(
+            self.other_lesson.read_text(encoding="utf-8"),
+            "untouched sibling lesson",
+        )
+        self.assertEqual(result, REVISION.lesson_revision(candidate))
+        self.assertFalse(self.draft.exists())
+
+    def test_stale_base_keeps_the_published_lesson(self) -> None:
+        with self.assertRaisesRegex(ValueError, "stale lesson revision"):
+            self.publish(self.original, "fnv1a32:00000000")
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), self.original)
+
+    def test_changed_source_anchor_is_refused(self) -> None:
+        with self.assertRaisesRegex(ValueError, "source anchors"):
+            self.publish(FIXTURE.quality_lesson_html(anchor="伪造位置 §9"))
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), self.original)
+
+    def test_changed_title_is_refused(self) -> None:
+        with self.assertRaisesRegex(ValueError, "title"):
+            self.publish(self.original.replace(
+                "<h1>根据证据完成一次判断</h1>",
+                "<h1>另一节课</h1>",
+            ))
+        self.assertEqual(self.lesson.read_text(encoding="utf-8"), self.original)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/apps/kimi-web/study-skills/test_install_study_skills.py b/apps/kimi-web/study-skills/test_install_study_skills.py
index f8bdf3d0..5d87ab1b 100644
--- a/apps/kimi-web/study-skills/test_install_study_skills.py
+++ b/apps/kimi-web/study-skills/test_install_study_skills.py
@@ -14,7 +14,7 @@
 SPEC.loader.exec_module(INSTALLER)
 
 
-def write_minimal_skill(root: Path, name: str = "teach-quick", revision: str = "teach-quick-v2") -> Path:
+def write_minimal_skill(root: Path, name: str = "teach-quick", revision: str = "teach-quick-v4") -> Path:
     skill = root / name
     skill.mkdir(parents=True)
     (skill / "CONTRACT.json").write_text(
@@ -111,7 +111,7 @@ def flaky_replace(src: Path | str, dst: Path | str) -> None:
         self.assertEqual(INSTALLER.tree_digest(self.target), original_digest)
 
     def test_recursive_skill_md_scan_only_current_skill(self) -> None:
-        write_minimal_skill(self.destination, "teach-quick", "teach-quick-v2")
+        write_minimal_skill(self.destination, "teach-quick", "teach-quick-v4")
         # Simulate old installer pollution — must not be recreated by new installer,
         # and a destination scan after clean install must not see backups.
         pollution = self.destination / ".teach-quick.backup-deadbeef"
@@ -122,7 +122,7 @@ def test_recursive_skill_md_scan_only_current_skill(self) -> None:
         )
         # Clean install with replace from a proper source should not create new
         # backups under destination; remove pollution as operators should.
-        source = write_minimal_skill(self.root / "src2", "teach-quick", "teach-quick-v2")
+        source = write_minimal_skill(self.root / "src2", "teach-quick", "teach-quick-v4")
         # First remove pollution (operator step) then install
         shutil_rm = __import__("shutil").rmtree
         shutil_rm(pollution)
@@ -130,7 +130,7 @@ def test_recursive_skill_md_scan_only_current_skill(self) -> None:
         found = INSTALLER.discover_skill_md_paths(self.destination)
         self.assertEqual(found, [self.target / "SKILL.md"])
         text = found[0].read_text(encoding="utf-8")
-        self.assertIn("[contract:teach-quick-v2]", text)
+        self.assertIn("[contract:teach-quick-v4]", text)
         self.assertNotIn("[contract:teach-quick-v1]", text)
 
     def test_explicit_backup_dir_outside_destination_kept(self) -> None:
@@ -161,7 +161,7 @@ def test_backup_dir_inside_destination_rejected(self) -> None:
             )
 
     def test_install_replace_check_idempotent_loop(self) -> None:
-        source = write_minimal_skill(self.root / "pack", "teach-quick", "teach-quick-v2")
+        source = write_minimal_skill(self.root / "pack", "teach-quick", "teach-quick-v4")
         target = self.destination / "teach-quick"
         for _ in range(3):
             result = INSTALLER.install_skill(source, target, True)
diff --git a/apps/kimi-web/test/study-lesson-revision.test.ts b/apps/kimi-web/test/study-lesson-revision.test.ts
new file mode 100644
index 00000000..eebfbca7
--- /dev/null
+++ b/apps/kimi-web/test/study-lesson-revision.test.ts
@@ -0,0 +1,25 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  isLessonArtifactPath,
+  lessonArtifactRevision,
+} from '../src/study/domain/lessonRevision';
+
+describe('lesson artifact revision', () => {
+  it('produces the same documented UTF-8 FNV identity for Chinese HTML', () => {
+    expect(lessonArtifactRevision('<h1>第一课</h1>')).toBe('fnv1a32:7735397a');
+    expect(lessonArtifactRevision('<h1>第一课</h1>')).toBe(
+      lessonArtifactRevision('<h1>第一课</h1>'),
+    );
+    expect(lessonArtifactRevision('<h1>第二课</h1>')).not.toBe(
+      lessonArtifactRevision('<h1>第一课</h1>'),
+    );
+  });
+
+  it('accepts only published lesson artifact paths', () => {
+    expect(isLessonArtifactPath('lessons/0001-feedback-loops.html')).toBe(true);
+    expect(isLessonArtifactPath('lessons/../source/secret.html')).toBe(false);
+    expect(isLessonArtifactPath('/lessons/0001.html')).toBe(false);
+    expect(isLessonArtifactPath('reference/0001.html')).toBe(false);
+  });
+});
diff --git a/apps/kimi-web/test/study-runtime-foundation.test.ts b/apps/kimi-web/test/study-runtime-foundation.test.ts
index 607ba756..b52df32a 100644
--- a/apps/kimi-web/test/study-runtime-foundation.test.ts
+++ b/apps/kimi-web/test/study-runtime-foundation.test.ts
@@ -32,6 +32,13 @@ import { normalizeStudyQuestion } from '../src/study/runtime/studyRuntime';
 
 const NOW = '2026-07-17T00:00:00.000Z';
 
+function deferred<T>() {
+  let resolve!: (value: T) => void;
+  let reject!: (reason?: unknown) => void;
+  const promise = new Promise<T>((res, rej) => { resolve = res; reject = rej; });
+  return { promise, resolve, reject };
+}
+
 class MemoryStorage implements StudyStorage {
   readonly values = new Map<string, string>();
   getItem(key: string): string | null { return this.values.get(key) ?? null; }
@@ -65,6 +72,46 @@ class FakeRuntime implements StudyRuntimePort {
   watchDelay: Promise<void> | undefined;
   answerDelay: Promise<void> | undefined;
   generateError: Error | undefined;
+  generateDelay: Promise<void> | undefined;
+  readonly generateCalls: Array<{
+    readonly courseId: string;
+    readonly planRevision: string;
+  }> = [];
+  planChangeImpl:
+    | ((courseId: string, planRevision: string, instruction: string) => Promise<void>)
+    | undefined;
+  readonly planChangeCalls: Array<{
+    readonly courseId: string;
+    readonly planRevision: string;
+    readonly instruction: string;
+  }> = [];
+  readCourseTextImpl:
+    | ((courseId: string, path: string) => Promise<StudyTextLoad>)
+    | undefined;
+  lessonChangeImpl:
+    | ((courseId: string, path: string, baseRevision: string, instruction: string, operationId: string) => Promise<void>)
+    | undefined;
+  lessonRegenerationImpl:
+    | ((courseId: string, path: string, baseRevision: string, operationId: string) => Promise<void>)
+    | undefined;
+  readonly lessonChangeCalls: Array<{
+    readonly courseId: string;
+    readonly path: string;
+    readonly baseRevision: string;
+    readonly instruction: string;
+    readonly operationId: string;
+  }> = [];
+  readonly lessonRegenerationCalls: Array<{
+    readonly courseId: string;
+    readonly path: string;
+    readonly baseRevision: string;
+    readonly operationId: string;
+  }> = [];
+  loadSnapshotImpl:
+    | ((courseId: string) => Promise<StudyRuntimeSnapshotLoad>)
+    | undefined;
+  uploadImpl: (() => Promise<{ fileId: string; name: string; mediaType: string; size: number; sourceRevision: string }>) | undefined;
+  startImpl: ((input: StartCourseInput) => Promise<StudyCourseBinding>) | undefined;
   uploaded = {
     fileId: 'file-1',
     name: 'Book.pdf',
@@ -79,9 +126,10 @@ class FakeRuntime implements StudyRuntimePort {
   async listCourses(): Promise<StudyCourseBinding[]> {
     return this.currentBinding === undefined ? [] : [this.currentBinding];
   }
-  async uploadMaterial(): Promise<typeof this.uploaded> { return this.uploaded; }
+  async uploadMaterial(): Promise<typeof this.uploaded> { if (this.uploadImpl !== undefined) return this.uploadImpl(); return this.uploaded; }
   async startCourse(input: StartCourseInput): Promise<StudyCourseBinding> {
     this.startCalls.push(input);
+    if (this.startImpl !== undefined) { const result = await this.startImpl(input); this.currentBinding = result; this.snapshots.set(input.snapshot.courseId, input.snapshot); return result; }
     this.currentBinding = binding(input.snapshot.courseId);
     // The teaching engine writes its first artifacts asynchronously; by the
     // time the controller refreshes, the authoritative snapshot is readable.
@@ -94,6 +142,7 @@ class FakeRuntime implements StudyRuntimePort {
   }
   async loadSnapshot(courseId: string): Promise<StudyRuntimeSnapshotLoad> {
     this.loadCalls.push(courseId);
+    if (this.loadSnapshotImpl !== undefined) return this.loadSnapshotImpl(courseId);
     const snapshot = this.snapshots.get(courseId);
     return snapshot === undefined ? { status: 'missing' } : { status: 'ready', snapshot };
   }
@@ -110,15 +159,52 @@ class FakeRuntime implements StudyRuntimePort {
     if (this.answerDelay !== undefined) await this.answerDelay;
   }
   async dismissQuestion(): Promise<void> {}
-  async requestGeneration(): Promise<void> {
+  async requestGeneration(courseId: string, planRevision: string): Promise<void> {
+    this.generateCalls.push({ courseId, planRevision });
+    if (this.generateDelay !== undefined) await this.generateDelay;
     if (this.generateError !== undefined) throw this.generateError;
   }
-  async readCourseText(): Promise<StudyTextLoad> { return { status: 'missing' }; }
+  async readCourseText(courseId: string, path: string): Promise<StudyTextLoad> {
+    if (this.readCourseTextImpl !== undefined) return this.readCourseTextImpl(courseId, path);
+    return { status: 'missing' };
+  }
   async listCourseFiles(): Promise<readonly FsEntry[] | undefined> { return undefined; }
   async listCatalog(): Promise<readonly CertifiedCatalogMaterial[]> { return []; }
   async sendTutorMessage(): Promise<void> {}
   async listTutorMessages(): Promise<readonly AppMessage[]> { return []; }
-  async requestPlanChange(): Promise<void> {}
+  async requestPlanChange(
+    courseId: string,
+    planRevision: string,
+    instruction: string,
+  ): Promise<void> {
+    this.planChangeCalls.push({ courseId, planRevision, instruction });
+    if (this.planChangeImpl !== undefined) {
+      await this.planChangeImpl(courseId, planRevision, instruction);
+    }
+  }
+  async requestLessonChange(
+    courseId: string,
+    path: string,
+    baseRevision: string,
+    instruction: string,
+    operationId: string,
+  ): Promise<void> {
+    this.lessonChangeCalls.push({ courseId, path, baseRevision, instruction, operationId });
+    if (this.lessonChangeImpl !== undefined) {
+      await this.lessonChangeImpl(courseId, path, baseRevision, instruction, operationId);
+    }
+  }
+  async requestLessonRegeneration(
+    courseId: string,
+    path: string,
+    baseRevision: string,
+    operationId: string,
+  ): Promise<void> {
+    this.lessonRegenerationCalls.push({ courseId, path, baseRevision, operationId });
+    if (this.lessonRegenerationImpl !== undefined) {
+      await this.lessonRegenerationImpl(courseId, path, baseRevision, operationId);
+    }
+  }
 }
 
 describe('StudyCourseRegistry', () => {
@@ -193,7 +279,7 @@ describe('Study workspace configuration', () => {
 });
 
 describe('Study workflow pin', () => {
-  it('requires both the Skill name and advertised contract revision', () => {
+  it('requires the Skill name and an exact or bounded-compatible contract revision', () => {
     expect(installedSkillMatches(
       { name: 'teach-quick', description: '[contract:teach-quick-v1] Quick', source: 'user' },
       { name: 'teach-quick', contractRevision: 'teach-quick-v1' },
@@ -202,6 +288,30 @@ describe('Study workflow pin', () => {
       { name: 'teach-quick', description: 'legacy quick', source: 'user' },
       { name: 'teach-quick', contractRevision: 'teach-quick-v1' },
     )).toBe(false);
+    expect(installedSkillMatches(
+      { name: 'teach-quick', description: '[contract:teach-quick-v2] Quick', source: 'user' },
+      { name: 'teach-quick', contractRevision: 'teach-quick-v4' },
+    )).toBe(false);
+    expect(installedSkillMatches(
+      { name: 'teach-quick', description: '[contract:teach-quick-v1] Quick', source: 'user' },
+      { name: 'teach-quick', contractRevision: 'teach-quick-v4' },
+    )).toBe(false);
+    expect(installedSkillMatches(
+      { name: 'teach-quick', description: '[contract:teach-quick-v3] Quick', source: 'user' },
+      { name: 'teach-quick', contractRevision: 'teach-quick-v4' },
+    )).toBe(false);
+    expect(installedSkillMatches(
+      { name: 'teach-quick', description: '[contract:teach-quick-v4] Quick', source: 'user' },
+      { name: 'teach-quick', contractRevision: 'teach-quick-v2' },
+    )).toBe(true);
+    expect(installedSkillMatches(
+      { name: 'teach-quick', description: '[contract:teach-quick-v4] Quick', source: 'user' },
+      { name: 'teach-quick', contractRevision: 'teach-quick-v3' },
+    )).toBe(true);
+    expect(installedSkillMatches(
+      { name: 'teach-ria', description: '[contract:teach-ria-v4] Deep', source: 'user' },
+      { name: 'teach-quick', contractRevision: 'teach-quick-v4' },
+    )).toBe(false);
   });
 });
 
@@ -318,6 +428,96 @@ describe('KimiStudyRuntime pagination', () => {
     )).resolves.toMatchObject({ id: 'message-1' });
     expect(listMessages).toHaveBeenCalledTimes(2);
   });
+
+  it('coalesces and persists the same plan-edit operation id', async () => {
+    const gate = deferred<{ promptId: string; userMessageId: string }>();
+    const listMessages: KimiWebApi['listMessages'] = vi.fn(async () => ({
+      items: [],
+      hasMore: false,
+    }));
+    const submitPrompt: KimiWebApi['submitPrompt'] = vi.fn(() => gate.promise);
+    const runtime = runtimeWith({ listMessages, submitPrompt }, true);
+
+    const first = runtime.requestPlanChange(
+      'course-12345678',
+      'plan-v1',
+      '缩减为六节课',
+    );
+    const duplicate = runtime.requestPlanChange(
+      'course-12345678',
+      'plan-v1',
+      '缩减为六节课',
+    );
+    await vi.waitFor(() => { expect(submitPrompt).toHaveBeenCalledTimes(1); });
+    gate.resolve({ promptId: 'prompt-plan-edit-1', userMessageId: 'message-plan-edit-1' });
+    await Promise.all([first, duplicate]);
+
+    await runtime.requestPlanChange('course-12345678', 'plan-v1', '缩减为六节课');
+    expect(submitPrompt).toHaveBeenCalledTimes(1);
+    expect(submitPrompt).toHaveBeenCalledWith('session-1', expect.objectContaining({
+      metadata: expect.objectContaining({
+        kimiStudyCourseId: 'course-12345678',
+        kimiStudyPlanRevision: 'plan-v1',
+      }),
+    }));
+  });
+
+  it('coalesces one lesson revision operation and carries its stale-write guard', async () => {
+    const gate = deferred<{ promptId: string; userMessageId: string }>();
+    const listMessages: KimiWebApi['listMessages'] = vi.fn(async () => ({
+      items: [],
+      hasMore: false,
+    }));
+    const submitPrompt: KimiWebApi['submitPrompt'] = vi.fn(() => gate.promise);
+    const runtime = runtimeWith({ listMessages, submitPrompt }, true);
+
+    const first = runtime.requestLessonChange(
+      'course-12345678',
+      'lessons/0001-feedback.html',
+      'fnv1a32:1234abcd',
+      '增加一个面向初学者的解释',
+      'lesson-op-12345678',
+    );
+    const duplicate = runtime.requestLessonChange(
+      'course-12345678',
+      'lessons/0001-feedback.html',
+      'fnv1a32:1234abcd',
+      '增加一个面向初学者的解释',
+      'lesson-op-12345678',
+    );
+    await vi.waitFor(() => { expect(submitPrompt).toHaveBeenCalledTimes(1); });
+    gate.resolve({ promptId: 'prompt-lesson-1', userMessageId: 'message-lesson-1' });
+    await Promise.all([first, duplicate]);
+
+    await runtime.requestLessonChange(
+      'course-12345678',
+      'lessons/0001-feedback.html',
+      'fnv1a32:1234abcd',
+      '增加一个面向初学者的解释',
+      'lesson-op-12345678',
+    );
+    expect(submitPrompt).toHaveBeenCalledTimes(1);
+    expect(submitPrompt).toHaveBeenCalledWith('session-1', expect.objectContaining({
+      metadata: expect.objectContaining({
+        kimiStudyLessonOperation: 'revise',
+        kimiStudyLessonPath: 'lessons/0001-feedback.html',
+        kimiStudyLessonBaseRevision: 'fnv1a32:1234abcd',
+      }),
+    }));
+  });
+
+  it('rejects an unsafe lesson target before submitting regeneration', async () => {
+    const submitPrompt: KimiWebApi['submitPrompt'] = vi.fn();
+    const runtime = runtimeWith({ submitPrompt }, true);
+
+    await expect(runtime.requestLessonRegeneration(
+      'course-12345678',
+      '../source/private.html',
+      'fnv1a32:1234abcd',
+      'lesson-op-12345678',
+    )).rejects.toThrow('lesson path');
+    expect(submitPrompt).not.toHaveBeenCalled();
+  });
 });
 
 describe('StudyProductController', () => {
@@ -392,13 +592,6 @@ describe('generation revision gate', () => {
 });
 
 describe('StudyProductController concurrency guards', () => {
-  function deferred<T>() {
-    let resolve!: (value: T) => void;
-    let reject!: (reason?: unknown) => void;
-    const promise = new Promise<T>((res, rej) => { resolve = res; reject = rej; });
-    return { promise, resolve, reject };
-  }
-
   function quickSnapshot(courseId: string): CourseSnapshot {
     const draft = createUploadCourse(courseId, {
       fileId: 'file-1',
@@ -410,6 +603,41 @@ describe('StudyProductController concurrency guards', () => {
     return applyCourseEvent(draft, { type: 'mode_selected', mode: 'quick' }, NOW);
   }
 
+  function readySnapshot(courseId: string, planRevision = 'plan-v1'): CourseSnapshot {
+    let ready = quickSnapshot(courseId);
+    ready = applyCourseEvent(ready, {
+      type: 'source_updated',
+      source: {
+        ...ready.source,
+        status: 'ready',
+        evidenceLevel: 'survey',
+        quickSurveyRevision: 'survey-v1',
+      },
+      approval: {
+        actor: 'auto_policy',
+        policyRevision: 'auto-v1',
+        approvedRevision: 'survey-v1',
+        approvedAt: NOW,
+      },
+    }, NOW);
+    ready = applyCourseEvent(ready, {
+      type: 'mission_updated',
+      mission: { status: 'ready', revision: 1, questionsAsked: 1, summary: '通过考试。' },
+    }, NOW);
+    return applyCourseEvent(ready, {
+      type: 'plan_updated',
+      plan: {
+        status: 'ready',
+        revision: planRevision,
+        basedOnSourceRevision: ready.source.revision,
+        basedOnMissionRevision: ready.mission.revision,
+        chapterCount: 3,
+        pageCount: 6,
+        quizCount: 1,
+      },
+    }, NOW);
+  }
+
   function readyQuestion(questionId: string): StudyQuestion {
     const normalized = normalizeStudyQuestion({
       questionId,
@@ -426,8 +654,10 @@ describe('StudyProductController concurrency guards', () => {
   }
 
   function makeController(runtime: FakeRuntime): StudyProductController {
+    let operation = 0;
     return new StudyProductController(runtime, {
       createCourseId: () => 'course-12345678',
+      createOperationId: () => `lesson-op-test-${++operation}`,
       now: () => NOW,
       missingRetryDelays: [],
     });
@@ -489,15 +719,256 @@ describe('StudyProductController concurrency guards', () => {
     await controller.open('course-b');
     const loadsAfterOpen = runtime.loadCalls.length;
 
-    runtime.handlersByCourse.get('course-a')?.onArtifactChanged();
+    runtime.handlersByCourse.get('course-a')?.onArtifactChanged('resync');
     await Promise.resolve();
     expect(runtime.loadCalls).toHaveLength(loadsAfterOpen);
 
-    runtime.handlersByCourse.get('course-b')?.onArtifactChanged();
-    await vi.waitFor(() => expect(runtime.loadCalls).toHaveLength(loadsAfterOpen + 1));
+    runtime.handlersByCourse.get('course-b')?.onArtifactChanged('resync');
+    await vi.waitFor(() => { expect(runtime.loadCalls).toHaveLength(loadsAfterOpen + 1); });
     expect(runtime.loadCalls.at(-1)).toBe('course-b');
   });
 
+  it('keeps the newest snapshot when an older same-course read resolves late', async () => {
+    const runtime = new FakeRuntime();
+    const original = readySnapshot('course-12345678');
+    const revised = applyCourseEvent(original, {
+      type: 'plan_updated',
+      plan: {
+        ...original.plan,
+        revision: 'plan-v2',
+        chapterCount: 4,
+      },
+    }, NOW);
+    runtime.snapshots.set('course-12345678', original);
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    const older = deferred<StudyRuntimeSnapshotLoad>();
+    const newer = deferred<StudyRuntimeSnapshotLoad>();
+    let reads = 0;
+    runtime.loadSnapshotImpl = async () => {
+      reads += 1;
+      return reads === 1 ? older.promise : newer.promise;
+    };
+    const slowRefresh = controller.refresh();
+    const fastRefresh = controller.refresh();
+    newer.resolve({ status: 'ready', snapshot: revised });
+    await fastRefresh;
+    older.resolve({ status: 'ready', snapshot: original });
+    await slowRefresh;
+
+    expect(controller.view.snapshot?.plan.revision).toBe('plan-v2');
+    expect(controller.view.snapshot?.plan.chapterCount).toBe(4);
+  });
+
+  it('coalesces duplicate outline changes and waits for a new authoritative revision', async () => {
+    const runtime = new FakeRuntime();
+    const original = readySnapshot('course-12345678');
+    runtime.snapshots.set('course-12345678', original);
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    const gate = deferred<void>();
+    runtime.planChangeImpl = async () => gate.promise;
+    const first = controller.requestPlanChange('缩减为六节课');
+    const duplicate = controller.requestPlanChange('  缩减为六节课  ');
+    await vi.waitFor(() => {
+      expect(runtime.planChangeCalls).toHaveLength(1);
+      expect(controller.view.planChange.status).toBe('submitting');
+    });
+    await expect(controller.requestPlanChange('先讲案例再讲原理'))
+      .rejects.toThrow('still in progress');
+    gate.resolve(undefined);
+    await Promise.all([first, duplicate]);
+    expect(controller.view.planChange).toEqual({
+      status: 'waiting',
+      baseRevision: 'plan-v1',
+    });
+
+    const revised = applyCourseEvent(original, {
+      type: 'plan_updated',
+      plan: {
+        ...original.plan,
+        revision: 'plan-v2',
+        pageCount: 5,
+      },
+    }, NOW);
+    runtime.snapshots.set('course-12345678', revised);
+    runtime.handlers?.onArtifactChanged('session_idle');
+    await vi.waitFor(() => { expect(controller.view.planChange.status).toBe('succeeded'); });
+
+    expect(controller.view.planChange).toEqual({
+      status: 'succeeded',
+      baseRevision: 'plan-v1',
+      resultRevision: 'plan-v2',
+    });
+    expect(controller.view.snapshot?.plan.revision).toBe('plan-v2');
+    expect(runtime.startCalls).toHaveLength(0);
+  });
+
+  it('keeps the last valid outline on failure and allows an exact retry', async () => {
+    const runtime = new FakeRuntime();
+    const original = readySnapshot('course-12345678');
+    runtime.snapshots.set('course-12345678', original);
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+    const before = controller.view.snapshot;
+
+    runtime.planChangeImpl = async () => { throw new Error('submit unavailable'); };
+    await expect(controller.requestPlanChange('面向零基础读者'))
+      .rejects.toThrow('submit unavailable');
+    expect(controller.view.planChange.status).toBe('failed');
+    expect(controller.view.snapshot).toBe(before);
+
+    runtime.planChangeImpl = async () => {};
+    await controller.requestPlanChange('面向零基础读者');
+    expect(runtime.planChangeCalls).toHaveLength(2);
+    expect(controller.view.planChange.status).toBe('waiting');
+
+    // A real session-idle event without a new ready revision is a recoverable
+    // failure, not permission to discard the previous outline.
+    runtime.handlers?.onArtifactChanged('session_idle');
+    await vi.waitFor(() => { expect(controller.view.planChange.status).toBe('failed'); });
+    expect(controller.view.snapshot?.plan.revision).toBe('plan-v1');
+    expect(controller.view.stage).toBe('working');
+  });
+
+  it('keeps the last valid outline when the completed edit leaves no snapshot', async () => {
+    const runtime = new FakeRuntime();
+    const original = readySnapshot('course-12345678');
+    runtime.snapshots.set('course-12345678', original);
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    runtime.planChangeImpl = async () => {};
+    await controller.requestPlanChange('把风险分析移到最前面');
+    runtime.loadSnapshotImpl = async () => ({ status: 'missing' });
+    runtime.handlers?.onArtifactChanged('session_idle');
+    await vi.waitFor(() => { expect(controller.view.planChange.status).toBe('failed'); });
+
+    expect(controller.view.snapshot).toBe(original);
+    expect(controller.view.stage).toBe('working');
+    expect(controller.view.issues).toEqual([]);
+  });
+
+  it('rejects an empty outline instruction before calling the runtime', async () => {
+    const runtime = new FakeRuntime();
+    runtime.snapshots.set('course-12345678', readySnapshot('course-12345678'));
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    await expect(controller.requestPlanChange('   ')).rejects.toThrow('empty');
+    expect(runtime.planChangeCalls).toHaveLength(0);
+  });
+
+  it('coalesces one current-lesson revision and waits for a changed artifact', async () => {
+    const runtime = new FakeRuntime();
+    runtime.snapshots.set('course-12345678', readySnapshot('course-12345678'));
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    let lesson = '<html><title>第一课</title><body>旧版本</body></html>';
+    runtime.readCourseTextImpl = async () => ({
+      status: 'ready',
+      content: lesson,
+      truncated: false,
+    });
+    const gate = deferred<void>();
+    runtime.lessonChangeImpl = async () => gate.promise;
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    const first = controller.requestLessonChange(
+      'lessons/0001-first.html',
+      '增加一个初学者能理解的例子',
+    );
+    const duplicate = controller.requestLessonChange(
+      'lessons/0001-first.html',
+      '  增加一个初学者能理解的例子  ',
+    );
+    await vi.waitFor(() => {
+      expect(runtime.lessonChangeCalls).toHaveLength(1);
+      expect(controller.view.lessonOperation.status).toBe('submitting');
+    });
+    await expect(controller.requestLessonChange(
+      'lessons/0001-first.html',
+      '改写为专家版本',
+    )).rejects.toThrow('still in progress');
+    gate.resolve();
+    await Promise.all([first, duplicate]);
+    expect(controller.view.lessonOperation.status).toBe('waiting');
+
+    runtime.handlers?.onArtifactChanged('resync');
+    await Promise.resolve();
+    expect(controller.view.lessonOperation.status).toBe('waiting');
+
+    lesson = '<html><title>第一课</title><body>加入解释后的新版本</body></html>';
+    runtime.handlers?.onArtifactChanged('session_idle');
+    await vi.waitFor(() => { expect(controller.view.lessonOperation.status).toBe('succeeded'); });
+    expect(controller.view.lessonOperation).toMatchObject({
+      kind: 'revise',
+      path: 'lessons/0001-first.html',
+      baseRevision: runtime.lessonChangeCalls[0]?.baseRevision,
+    });
+    expect(controller.view.lessonOperation.resultRevision).not.toBe(
+      controller.view.lessonOperation.baseRevision,
+    );
+  });
+
+  it('keeps the previous lesson on failure and gives an explicit retry a new operation id', async () => {
+    const runtime = new FakeRuntime();
+    runtime.snapshots.set('course-12345678', readySnapshot('course-12345678'));
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    let lesson = '<html><title>第一课</title><body>最后有效版本</body></html>';
+    runtime.readCourseTextImpl = async () => ({
+      status: 'ready',
+      content: lesson,
+      truncated: false,
+    });
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    await controller.requestLessonRegeneration('lessons/0001-first.html');
+    runtime.handlers?.onArtifactChanged('session_idle');
+    await vi.waitFor(() => { expect(controller.view.lessonOperation.status).toBe('failed'); });
+
+    await controller.requestLessonRegeneration('lessons/0001-first.html');
+    expect(runtime.lessonRegenerationCalls).toHaveLength(2);
+    expect(runtime.lessonRegenerationCalls[1]?.operationId).not.toBe(
+      runtime.lessonRegenerationCalls[0]?.operationId,
+    );
+    lesson = '<html><title>第一课</title><body>重生成后的有效版本</body></html>';
+    runtime.handlers?.onArtifactChanged('session_idle');
+    await vi.waitFor(() => { expect(controller.view.lessonOperation.status).toBe('succeeded'); });
+  });
+
+  it('drops a lesson request whose base read finishes after switching courses', async () => {
+    const runtime = new FakeRuntime();
+    runtime.snapshots.set('course-a', readySnapshot('course-a'));
+    runtime.snapshots.set('course-b', readySnapshot('course-b'));
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const read = deferred<StudyTextLoad>();
+    runtime.readCourseTextImpl = async () => read.promise;
+    const controller = makeController(runtime);
+    await controller.open('course-a');
+
+    const stale = controller.requestLessonChange('lessons/0001-first.html', '补充例子');
+    await controller.open('course-b');
+    read.resolve({
+      status: 'ready',
+      content: '<html><title>第一课</title><body>旧课程</body></html>',
+      truncated: false,
+    });
+    await stale;
+
+    expect(runtime.lessonChangeCalls).toHaveLength(0);
+    expect(controller.view.snapshot?.courseId).toBe('course-b');
+    expect(controller.view.lessonOperation.status).toBe('idle');
+  });
+
   it('keeps a newer question that arrived while an answer was in flight', async () => {
     const runtime = new FakeRuntime();
     const controller = makeController(runtime);
@@ -573,6 +1044,26 @@ describe('StudyProductController concurrency guards', () => {
     expect(controller.view.snapshot?.generation.status).not.toBe('generating');
   });
 
+  it('confirms one plan revision only once when generation is double-clicked', async () => {
+    const runtime = new FakeRuntime();
+    runtime.snapshots.set('course-12345678', readySnapshot('course-12345678'));
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+    await controller.open('course-12345678');
+
+    const gate = deferred<void>();
+    runtime.generateDelay = gate.promise;
+    const first = controller.generate();
+    const duplicate = controller.generate();
+    await duplicate;
+    expect(runtime.generateCalls).toEqual([{
+      courseId: 'course-12345678',
+      planRevision: 'plan-v1',
+    }]);
+    gate.resolve(undefined);
+    await first;
+  });
+
   it('refreshes the authoritative snapshot after upgrade without a watcher event', async () => {
     const runtime = new FakeRuntime();
     const controller = makeController(runtime);
@@ -597,6 +1088,30 @@ describe('StudyProductController concurrency guards', () => {
     expect(controller.view.stage).toBe('working');
   });
 
+  it('coalesces a double-clicked deepen request and keeps Quick artifacts on failure', async () => {
+    const runtime = new FakeRuntime();
+    const controller = makeController(runtime);
+    await controller.upload(new File(['book'], 'Book.pdf'));
+    await controller.selectMode('quick');
+    const quick = controller.view.snapshot;
+    const startsBeforeDeepen = runtime.startCalls.length;
+    const gate = deferred<StudyCourseBinding>();
+    runtime.startImpl = async () => gate.promise;
+
+    const first = controller.upgradeToDeep();
+    const duplicate = controller.upgradeToDeep();
+    await duplicate;
+    expect(runtime.startCalls).toHaveLength(startsBeforeDeepen + 1);
+    expect(controller.view.snapshot).toBe(quick);
+    expect(controller.view.snapshot?.profile?.mode).toBe('quick');
+
+    gate.reject(new Error('deepening unavailable'));
+    await expect(first).rejects.toThrow('deepening unavailable');
+    expect(controller.view.snapshot).toBe(quick);
+    expect(controller.view.stage).toBe('error');
+    expect(controller.view.issues[0]?.code).toBe('upgrade_failed');
+  });
+
   it('shows a recoverable error when the snapshot stays missing after start', async () => {
     const runtime = new FakeRuntime();
     runtime.resumeImpl = async (courseId) => binding(courseId);
@@ -606,4 +1121,54 @@ describe('StudyProductController concurrency guards', () => {
     expect(controller.view.stage).toBe('error');
     expect(controller.view.issues[0]?.code).toBe('artifact_not_found');
   });
+
+  it('invokes startCourse exactly once for upload + quick mode', async () => {
+    const runtime = new FakeRuntime();
+    const controller = makeController(runtime);
+    await controller.upload(new File(['book'], 'Book.pdf'));
+    expect(controller.view.stage).toBe('mode_selection');
+
+    await controller.selectMode('quick');
+    expect(runtime.startCalls).toHaveLength(1);
+
+    // Re-calling selectMode with quick again is rejected by the domain event
+    await expect(controller.selectMode('quick')).rejects.toThrow();
+    expect(runtime.startCalls).toHaveLength(1);
+    expect(controller.view.stage).toBe('working'); // Sync domain rejection before try/catch
+  });
+
+  it('does not call startCourse when the upload itself fails', async () => {
+    const runtime = new FakeRuntime();
+    runtime.uploadImpl = () => { throw new Error('upload failure'); };
+    const controller = makeController(runtime);
+    await expect(controller.upload(new File(['book'], 'Book.pdf'))).rejects.toThrow('upload failure');
+    expect(runtime.startCalls).toHaveLength(0);
+    expect(controller.view.stage).toBe('error');
+  });
+
+  it('preserves a recoverable error state when selectMode fails', async () => {
+    const runtime = new FakeRuntime();
+    runtime.startImpl = () => { throw new Error('start refused'); };
+    const controller = makeController(runtime);
+    await controller.upload(new File(['book'], 'Book.pdf'));
+    await expect(controller.selectMode('quick')).rejects.toThrow('start refused');
+
+    expect(controller.view.stage).toBe('error');
+    expect(controller.view.issues).toHaveLength(1);
+    expect(controller.view.snapshot).not.toBeNull();
+  });
+
+  it('keeps historical course open path unchanged after auto-Quick changes', async () => {
+    const runtime = new FakeRuntime();
+    runtime.snapshots.set('course-historic', quickSnapshot('course-historic'));
+    runtime.resumeImpl = async (courseId) => binding(courseId);
+    const controller = makeController(runtime);
+
+    const opened = await controller.open('course-historic');
+    expect(opened).toBe(true);
+    expect(controller.view.binding?.courseId).toBe('course-historic');
+    expect(controller.view.snapshot?.courseId).toBe('course-historic');
+    expect(runtime.startCalls).toHaveLength(0);
+  });
+
 });
diff --git a/apps/kimi-web/test/study-screen-model.test.ts b/apps/kimi-web/test/study-screen-model.test.ts
index 920b5fbe..a0ad2d41 100644
--- a/apps/kimi-web/test/study-screen-model.test.ts
+++ b/apps/kimi-web/test/study-screen-model.test.ts
@@ -81,6 +81,8 @@ function view(patch: Partial<StudyProductView>): StudyProductView {
     readiness: READY,
     connected: true,
     issues: [],
+    planChange: { status: 'idle' },
+    lessonOperation: { status: 'idle' },
     ...patch,
   };
 }
@@ -114,6 +116,36 @@ describe('deriveStudyScreen', () => {
     expect(model.busy).toBe(true);
   });
 
+  it('keeps the outline busy until an authoritative revised plan arrives', () => {
+    const model = deriveStudyScreen(view({
+      stage: 'working',
+      snapshot: readySnapshot(),
+      planChange: { status: 'waiting', baseRevision: 'plan-v1' },
+    }));
+    expect(model.screen).toBe('outline');
+    expect(model.busy).toBe(true);
+  });
+
+  it('keeps the reader visible and busy while its current lesson is replaced', () => {
+    const model = deriveStudyScreen(view({
+      stage: 'ready',
+      snapshot: readySnapshot({
+        status: 'ready',
+        planRevision: 'plan-v1',
+        publishedLessons: 3,
+        totalLessons: 3,
+      }),
+      lessonOperation: {
+        status: 'waiting',
+        kind: 'revise',
+        path: 'lessons/0001-feedback.html',
+        baseRevision: 'fnv1a32:12345678',
+      },
+    }));
+    expect(model.screen).toBe('learning');
+    expect(model.busy).toBe(true);
+  });
+
   it('shows the one-time mode decision after upload', () => {
     const draft = createUploadCourse('course-12345678', {
       fileId: 'file-1',