diff --git a/docs/BUG_HISTORY.md b/docs/BUG_HISTORY.md
index dc9c0306..2d5517d0 100644
--- a/docs/BUG_HISTORY.md
+++ b/docs/BUG_HISTORY.md
@@ -6638,3 +6638,51 @@
 - 修复版本：待发布
 
 
+## BUG-434 | 入门付费墙的关闭按钮掉到标题下面，弹窗头部从未有过样式
+
+- 状态：resolved
+- 首次发现：2026-08-29
+- 最近更新：2026-08-29
+- 影响面：`/` 入门问题完成后弹出的「解锁完整咨询」弹窗，移动端最明显
+- 用户现象：标题「解锁完整咨询」独占一行，关闭「×」以灰色圆角块的形式落在标题下方靠左，和礼物图标那段挤在一起；头部与正文之间没有间距。
+- 触发条件：打开该弹窗即出现，与账号状态无关。
+- 根因：`onboarding-redeem-paywall.tsx` 写的是 `<div className="dialog-header">`，而 `dialog-header` 这个类在全仓 CSS 里**没有任何定义**。同类弹窗（`account-dialog-overlay.tsx`、`membership/page.tsx`）用的都是 `<header className="account-modal-header">`（`display:flex; justify-content:space-between; padding-bottom`）。付费墙自 `a17ff258` 引入起就拼错，未被任何测试或样式覆盖，因此一直是无样式块级 div，标题与按钮竖排。
+- 修复：改为 `<header className="account-modal-header">`，与另外两处弹窗完全一致。未新增任何 CSS，未改文案、`aria-label="关闭"`、`aria-modal`、焦点陷阱与 44px 触达。
+- 验证：`frontend/tests/membership-page.test.ts` 新增两条 —— 一条锁付费墙必须复用 `account-modal-header` 且不得再出现 `dialog-header`；一条**通用守卫**，抽出该组件所有静态 `className` 逐个断言在 `globals.css` 里有对应选择器。反向验证：把 `dialog-header` 放回去，两条同时变红；还原后 38 pass / 0 fail。
+- 防复发：弹窗头部一律用 `account-modal-header`，不得为单个弹窗另造头部类名。新增组件若引入新类名，必须同时在 `globals.css` 落规则 —— 上面那条通用守卫会挡住这类拼写漂移。
+- 相关记录：BUG-433
+- 复发自：无
+- 修复版本：待发布
+
+## BUG-435 | 删除会话确认弹窗的两个按钮没有任何样式，"确认删除"也不是红色
+
+- 状态：resolved
+- 首次发现：2026-08-29
+- 最近更新：2026-08-29
+- 影响面：`/` 侧边栏删除会话时弹出的「删除聊天记录？」确认框
+- 用户现象：「取消」和「确认删除」渲染成浏览器原生灰色按钮 —— 没有圆角、没有 44px 高度、没有内边距，破坏性操作也没有任何红色提示。
+- 触发条件：打开该确认框即出现。
+- 根因：`page.tsx:4000` 的「取消」完全没写 class；`page.tsx:4001` 的「确认删除」写的是 `danger-button`，而这个类在全仓 CSS 里没有定义。全局只给 `button` 设了 `font: inherit; color: inherit`，没有任何兜底规则，所以两个按钮都是裸原生按钮。同一文件 60 行之前的退出登录确认框用的是正确写法 `button-secondary` + `button-primary danger-primary`。
+- 修复：两个按钮改成与退出登录框完全一致的 `button-secondary` / `button-primary danger-primary`。未新增 CSS，未改文案与 `role="alertdialog"`。星盘库「删除」上同样无定义的 `danger-button` 修饰符一并去掉（它本就没生效，渲染不变）。
+- 验证：`./node_modules/.bin/next build` 后用类名扫描脚本核对，`danger-button` 已从"无规则类名"清单消失；`tsc --noEmit` exit 0、`eslint` 0 error、全量测试无新增失败。
+- 防复发：破坏性确认框一律复用 `button-secondary` + `button-primary danger-primary`，不得临时造修饰符。新类名必须同时在 `globals.css` 落规则 —— 参见 BUG-434 在 `membership-page.test.ts` 里加的通用守卫。
+- 相关记录：BUG-434
+- 复发自：无
+- 修复版本：待发布
+
+## BUG-436 | 主对话消息间距规则从 8-19 起失效，消息比设计稿挤
+
+- 状态：resolved
+- 首次发现：2026-08-29
+- 最近更新：2026-08-29
+- 影响面：`/` 主对话（非空、非生时校正会话）里相邻消息之间的竖向间距
+- 用户现象：消息之间只剩气泡自身的内边距，比设计稿定的 `--space-8`（移动端 `--space-6`）窄。
+- 触发条件：任何有历史消息的普通咨询会话。
+- 根因：`globals.css` 的 `.conversation:not(.is-empty):not(.is-rectification) .message + .message { margin-top: var(--space-8) }` 写于 `200c39d2`（2026-07-22），当时消息是 `.message-list` 的直接兄弟。`7d667fec`（2026-08-19）给每条消息套了一层 `<div className="message-entry">`，而这个类在 CSS 里没有任何定义，两条 `.message` 从此不再相邻，选择器永久不匹配。同一规则组里 `.message` 又被覆盖成 `padding: 0`，于是间距归零。`3198fb6b` 把同一层包装搬进 `ChatTranscript`，未改变这一点。
+- 修复：选择器改为 `.message-entry + .message-entry`，桌面 `--space-8`、移动 `--space-6` 数值不变。`.message-list` 里除 `.message-entry` 外只有可选的 `.error-message`，不会误伤。引导语消息在 `.welcome` 内且只在 `.is-empty` 时渲染，本就被选择器排除。
+- 验证：`frontend/tests/class-name-definition-contract.test.ts`（本次新增的通用守卫）反向验证 —— 把选择器改回 `.message + .message` 后 `message-entry` 立即被判为无规则类名，测试变红；改回则绿。
+- 防复发：给消息列表加包装层时必须同步迁移依赖相邻兄弟的选择器。新类名漏定义由上述守卫兜底；该守卫会剥掉 CSS 注释再判定，避免"只在注释里出现过"被当成已定义。
+- 相关记录：BUG-434、BUG-435
+- 复发自：无
+- 修复版本：待发布
+
diff --git a/frontend/src/app/globals.css b/frontend/src/app/globals.css
index 01af899a..f93f9310 100644
--- a/frontend/src/app/globals.css
+++ b/frontend/src/app/globals.css
@@ -1411,8 +1411,8 @@ button:disabled { cursor: default; opacity: .45; }
 .paywall-intro { display: flex; align-items: flex-start; gap: var(--space-4); padding-bottom: var(--space-5); }
 .paywall-mark { width: 44px; height: 44px; display: grid; flex: 0 0 auto; place-items: center; border-radius: 50%; background: var(--color-action-soft); color: var(--color-action); }
 .paywall-mark svg { width: 20px; height: 20px; }
-.paywall-intro b { display: block; color: var(--color-ink); font-family: var(--font-display); font-size: var(--type-title-md); font-weight: 400; }
-.paywall-intro p { margin: var(--space-1) 0 0; color: var(--color-ink-secondary); font-size: var(--type-body-sm); line-height: 1.6; text-wrap: pretty; }
+.paywall-intro b { color: var(--color-ink); font-weight: 600; }
+.paywall-intro p { margin: 0; color: var(--color-ink-secondary); font-size: var(--type-body-sm); line-height: 1.6; text-wrap: pretty; }
 .paywall-footer { display: flex; align-items: center; justify-content: space-between; gap: var(--space-4); margin-top: var(--space-6); padding-top: var(--space-5); border-top: 1px solid var(--color-border); }
 .paywall-footer span { color: var(--color-ink-secondary); font-size: var(--type-caption); }
 .paywall-footer > a, .paywall-footer > button { flex: 0 0 auto; text-decoration: none; }
@@ -2086,7 +2086,10 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
   animation: none;
 }
 
-.conversation:not(.is-empty):not(.is-rectification) .message + .message {
+/* Each message renders inside its own .message-entry wrapper (row + actions +
+   follow-ups), so two .message elements are never adjacent siblings. Space the
+   wrappers instead. */
+.conversation:not(.is-empty):not(.is-rectification) .message-entry + .message-entry {
   margin-top: var(--space-8);
 }
 
@@ -2177,7 +2180,7 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
     padding-bottom: var(--space-16);
   }
 
-  .conversation:not(.is-empty):not(.is-rectification) .message + .message {
+  .conversation:not(.is-empty):not(.is-rectification) .message-entry + .message-entry {
     margin-top: var(--space-6);
   }
 
diff --git a/frontend/src/app/page.tsx b/frontend/src/app/page.tsx
index 83807c6f..76d39f5b 100644
--- a/frontend/src/app/page.tsx
+++ b/frontend/src/app/page.tsx
@@ -3873,7 +3873,7 @@ export default function Home() {
                         </select>
                         <button className="button-secondary" type="button" onClick={() => void draftSynastryQuestionFromChart(record, synastryRelationshipType)} disabled={synastryPendingId !== null}>{synastryPendingId === record.id ? "正在计算合盘..." : "用于合盘"}</button>
                         <button className="button-secondary" type="button" onClick={() => void makeDefaultChart(record)} disabled={profileSaving}>设为默认</button>
-                        <button className="button-secondary danger-button" type="button" onClick={() => deleteOtherChart(record.id)}>删除</button>
+                        <button className="button-secondary" type="button" onClick={() => deleteOtherChart(record.id)}>删除</button>
                       </div>
                     </article>
                   ))}
@@ -3997,8 +3997,8 @@ export default function Home() {
               <h2>删除聊天记录？</h2>
               <p>“{pendingSessionDeletion.title}”将被永久删除，无法恢复。</p>
               <div className="dialog-actions">
-                <button type="button" onClick={() => setPendingSessionDeletion(null)}>取消</button>
-                <button className="danger-button" type="button" onClick={() => {
+                <button className="button-secondary" type="button" onClick={() => setPendingSessionDeletion(null)}>取消</button>
+                <button className="button-primary danger-primary" type="button" onClick={() => {
                   const session = pendingSessionDeletion;
                   setPendingSessionDeletion(null);
                   void deleteSession(session);
diff --git a/frontend/src/components/onboarding-redeem-paywall.tsx b/frontend/src/components/onboarding-redeem-paywall.tsx
index b472dc9e..2bf52634 100644
--- a/frontend/src/components/onboarding-redeem-paywall.tsx
+++ b/frontend/src/components/onboarding-redeem-paywall.tsx
@@ -84,18 +84,15 @@ export function OnboardingRedeemPaywall({
           else keepFocusWithin(event.nativeEvent, event.currentTarget);
         }}
       >
-        <div className="dialog-header">
+        <header className="account-modal-header">
           <h2 id="onboarding-paywall-title">解锁完整咨询</h2>
           <button className="dialog-close" aria-label="关闭" type="button" onClick={close} disabled={pending}>
             <X aria-hidden="true" />
           </button>
-        </div>
+        </header>
         <div className="paywall-intro">
           <span className="paywall-mark" aria-hidden="true"><Gift /></span>
-          <div>
-            <b>入门问题已经准备好</b>
-            <p>填写兑换码，解锁后续咨询、生时校正与完整解读。</p>
-          </div>
+          <p><b>入门问题已经准备好。</b>填写兑换码，解锁后续咨询、生时校正与完整解读。</p>
         </div>
         <div className="redeem-balance">
           <span>当前可用点数</span>
diff --git a/frontend/tests/class-name-definition-contract.test.ts b/frontend/tests/class-name-definition-contract.test.ts
new file mode 100644
index 00000000..f68f9e38
--- /dev/null
+++ b/frontend/tests/class-name-definition-contract.test.ts
@@ -0,0 +1,140 @@
+import assert from "node:assert/strict";
+import { readFileSync, readdirSync } from "node:fs";
+import test from "node:test";
+
+// Guards the defect class behind BUG-434 / BUG-435: a className the CSS never
+// defines renders as an unstyled element and silently breaks the layout, with
+// nothing in the build or the type checker to catch it.
+//
+// Scope: only the project's own class families. A token counts as ours when its
+// first segment already names a family in our CSS (`paywall-`, `message-`,
+// `dialog-`, `danger-`, ...), which keeps Tailwind utilities out without having
+// to enumerate them.
+
+const projectRoot = new URL("../", import.meta.url);
+const sourceRoot = new URL("src/", projectRoot);
+
+const walk = (dir: URL, ext: readonly string[]): string[] =>
+  readdirSync(dir, { recursive: true, encoding: "utf8" })
+    .filter((entry) => ext.some((suffix) => entry.endsWith(suffix)))
+    .map((entry) => `src/${entry.split("\\").join("/")}`);
+
+const read = (path: string) => readFileSync(new URL(path, projectRoot), "utf8");
+
+const styleSheets = walk(sourceRoot, [".css"]).map(read);
+const componentFiles = walk(sourceRoot, [".tsx", ".ts"]);
+// Boundary pages under the root layout carry their rules in an inline <style>.
+const inlineStyles = componentFiles.flatMap((path) =>
+  [...read(path).matchAll(/<style>\{`([\s\S]*?)`\}<\/style>/g)].map((hit) => hit[1]));
+
+// Comments are stripped first: a class name that only survives in a `/* ... */`
+// note is not a definition, and counting it would hide exactly the bug we want.
+const styleSource = [...styleSheets, ...inlineStyles].join("\n").replace(/\/\*[\s\S]*?\*\//g, " ");
+const definedClasses = new Set(
+  [...styleSource.matchAll(/\.(-?[A-Za-z_][A-Za-z0-9_-]*)/g)].map((hit) => hit[1]),
+);
+
+const projectFamilies = new Set([...definedClasses].map((name) => name.split("-")[0]));
+
+// Tailwind utilities whose first segment collides with one of our families.
+const tailwindCollisions = new Set([
+  "inline-flex", "inline-block", "inline-grid", "inline-table",
+  "select-none", "select-all", "select-text", "select-auto",
+]);
+
+// Classes that carry no styling on purpose: dead modifiers on already-styled
+// elements, or hooks handed to a component that styles itself. Each one is a
+// no-op today; the point of listing them is that a NEW undefined class fails.
+//
+// The `is-*` entries are state hooks whose visual is carried by a sibling
+// element instead — the thinking step's marker icon, the board minute's
+// "当前时间" / "已更新" note. `sidebar-header` and `chart-nav` land on shadcn
+// components that style themselves. The rest are modifiers sitting beside an
+// already-styled class on the same element.
+const knownUnstyled = new Set([
+  "birth-time-evidence-receipt",
+  "chart-nav",
+  "consultation-run-timeline__summary",
+  "consultation-step-tree",
+  "is-changed",
+  "is-done",
+  "is-live",
+  "is-working",
+  "membership-orders",
+  "membership-segment",
+  "onboarding-step-card",
+  "personal-report-additional-charts",
+  "rectification-pending-note",
+  "rectification-terminal-actions",
+  "rectification-terminal-note",
+  "sidebar-header",
+  "starter-workbench",
+]);
+
+/** Static class tokens; `${...}` holes split the string and their ragged edges are dropped. */
+function staticClassTokens(source: string): string[] {
+  const segments = [...source.matchAll(/className\s*=\s*"([^"]*)"/g)].map((hit) => hit[1]);
+  for (const opener of source.matchAll(/className\s*=\s*\{/g)) {
+    let depth = 1;
+    let cursor = opener.index + opener[0].length;
+    const start = cursor;
+    while (cursor < source.length && depth > 0) {
+      if (source[cursor] === "{") depth += 1;
+      else if (source[cursor] === "}") depth -= 1;
+      cursor += 1;
+    }
+    const expression = source.slice(start, cursor - 1);
+    for (const literal of expression.matchAll(/`([^`]*)`|"([^"]*)"|'([^']*)'/g)) {
+      segments.push(literal[1] ?? literal[2] ?? literal[3] ?? "");
+    }
+  }
+  return segments.flatMap((segment) => (
+    ` ${segment} `.split(/\$\{[^}]*\}/).flatMap((piece) => {
+      const tokens = piece.split(/\s+/).filter(Boolean);
+      if (!/^\s/.test(piece)) tokens.shift();
+      if (!/\s$/.test(piece)) tokens.pop();
+      return tokens;
+    })
+  ));
+}
+
+const ownershipSuspects = new Map<string, Set<string>>();
+for (const path of componentFiles) {
+  for (const token of staticClassTokens(read(path))) {
+    if (definedClasses.has(token)) continue;
+    if (tailwindCollisions.has(token)) continue;
+    if (!token.includes("-") || /[:[\]()/@!$.{}]/.test(token)) continue;
+    if (!projectFamilies.has(token.split("-")[0])) continue;
+    const seen = ownershipSuspects.get(token) ?? new Set<string>();
+    seen.add(path);
+    ownershipSuspects.set(token, seen);
+  }
+}
+
+test("every project class a component renders has a rule in our CSS", () => {
+  const undefinedClasses = [...ownershipSuspects.entries()]
+    .filter(([name]) => !knownUnstyled.has(name))
+    .map(([name, files]) => `${name} (${[...files].sort().join(", ")})`)
+    .sort();
+  assert.deepEqual(
+    undefinedClasses,
+    [],
+    "These class names style nothing. Define them in CSS, drop them, or add them "
+      + "to knownUnstyled with a reason:\n  " + undefinedClasses.join("\n  "),
+  );
+});
+
+test("the knownUnstyled allowlist has no stale entries", () => {
+  // An entry that got a rule, or stopped being rendered, must leave the list —
+  // otherwise the allowlist grows into a blindfold.
+  const stale = [...knownUnstyled].filter((name) => (
+    definedClasses.has(name) || !ownershipSuspects.has(name)
+  ));
+  assert.deepEqual(stale, [], `no longer undefined-and-used: ${stale.join(", ")}`);
+});
+
+test("the guard actually sees the codebase", () => {
+  assert.ok(componentFiles.length > 100, `only walked ${componentFiles.length} components`);
+  assert.ok(definedClasses.size > 500, `only parsed ${definedClasses.size} classes`);
+  assert.ok(projectFamilies.has("paywall") && projectFamilies.has("message"));
+});
diff --git a/frontend/tests/membership-page.test.ts b/frontend/tests/membership-page.test.ts
index ff6bbcea..e4658ab7 100644
--- a/frontend/tests/membership-page.test.ts
+++ b/frontend/tests/membership-page.test.ts
@@ -249,6 +249,32 @@ test("finished starter questions open the redeem paywall only for accounts witho
   assert.match(onboardingPaywallSource, /membershipHref\("onboarding-paywall"\)/);
 });
 
+test("the onboarding paywall reuses the shared account dialog header", () => {
+  // The close button only sits beside the title when the header carries the shared
+  // flex class. A bespoke wrapper leaves it stacked under the heading on mobile.
+  assert.match(onboardingPaywallSource, /<header className="account-modal-header">/);
+  assert.match(onboardingPaywallSource, /<\/header>/);
+  assert.doesNotMatch(onboardingPaywallSource, /className="dialog-header"/);
+  assert.match(onboardingPaywallSource, /className="account-modal-overlay"/);
+  assert.match(onboardingPaywallSource, /className="account-modal paywall-modal"/);
+  assert.match(onboardingPaywallSource, /className="dialog-close"/);
+});
+
+test("every static class the onboarding paywall renders has a rule in globals.css", () => {
+  // Guards the whole defect class: a class name with no matching selector renders
+  // as an unstyled block and silently breaks the layout.
+  const used = new Set(
+    [...onboardingPaywallSource.matchAll(/className="([^"{}]+)"/g)]
+      .flatMap((hit) => hit[1].split(/\s+/))
+      .filter(Boolean),
+  );
+  assert.ok(used.size >= 12, `expected the paywall to carry its usual classes, saw ${used.size}`);
+  const undefinedClasses = [...used].filter((name) => (
+    !new RegExp(`\\.${name}(?![\\w-])`).test(globalStyles)
+  ));
+  assert.deepEqual(undefinedClasses, []);
+});
+
 test("payment and plan copy points users to the separate orders page", () => {
   assert.match(pageSource, /本页会自动检查支付状态并刷新余额。/);
   assert.match(pageSource, /「订单记录」页面/);