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Hatch `<mv-hatch>`

会话过期的“死人开关”：一个低调的倒计时标签（等宽数字像机械计数器一样滚动），必须有人在它归零前主动重置。

文化出处

《迷失》，J.J. 艾布拉姆斯、达蒙·林德洛夫和杰弗里·利伯（2004 年，剧集）。在地下舱里，必须有人在倒计时归零前输入密码，最后几分钟还会响起警报，否则系统就会失灵。在界面中，这变成了会话过期的失效保护开关：一个安静的倒计时会转为警报，必须在会话丢失之前主动重置。

工作原理

会话过期的“失效保护开关”（dead man’s switch）：一个低调的倒计时标签（等宽数字像机械计数器一样滚动），必须有人在它归零前主动重置。低于警告阈值时，它会变成一个醒目但非模态的警报面板（或设置 modal 时变为 <dialog>），带有大号倒计时、逐渐耗尽的计量条，以及“Stay signed in” / “Sign out”；可选的确认码需要输入后才能重置（适用于自助终端、高安全场景），还可以启用柔和的 WebAudio 提示音。重置会经过一个可取消的 mv-reset 事件，其 waitUntil(promise) 会在你的保活接口响应期间显示等待状态，并处理失败情况。时间由 Date.now() 截止时间推算（不受后台标签页节流影响），重置和过期通过 BroadcastChannel 在多个标签页之间同步；用户活动只能在平静阶段静默延长会话，警报一旦出现就不再生效。

分类	反馈
类型	Web Component（`<mv-hatch>`）
状态	稳定版
套件	诚实的系统状态
同时安装	button, input
Keywords	exclusive, culture, session, timeout, session-timeout, idle, keepalive, countdown, timer, expiry, logout, dead-mans-switch, security, kiosk, broadcast-channel, multi-tab, alarm, flip-digits

When to use

An authenticated app signs users out after a fixed or idle timeout and must warn them before unsaved work is lost
A shared kiosk or back-office terminal must prove someone is still present before extending a sensitive session
Several tabs share one server session and a keepalive in one tab must extend or end the session in all of them
Compliance requires a visible countdown and a deliberate, logged action to extend a session

Avoid when

The countdown is a product feature (sale ends, auction, quiz) rather than a session that must be kept alive
The user just needs to be told what changed while they were away, not to confirm presence → use While Away instead
The session never expires client-side or the server silently refreshes tokens; a countdown would only add anxiety

安装

node scripts/add.mjs hatch --out ./src/marvelous

使用 Marvelous UI MCP 服务器的 AI 智能体：install_components({ slugs: ["hatch"], target_dir: "<absolute path>/src/marvelous", framework: "react" })。

复制的文件（含依赖）：tokens/tokens.css, core/base.css, components/button/button.css, components/input/input.css, core/dismiss.js, core/dom.js, core/element.js, core/motion.js, core/position.js, components/hatch/hatch.js, components/hatch/hatch.css。

用法

快速开始，最小可运行标记：

<mv-hatch duration="15m" warn="2m" channel="app-session">
  <a slot="expired" href="/login">Sign in again</a>
</mv-hatch>

标准标记，可在此基础上通过属性、data-* 和 CSS 变量进行定制：

<div id="ht-demo" style="width:min(100%,52rem);margin-inline:auto">
  <style>
    #ht-demo { display:grid; gap:1rem; align-content:start }
    #ht-demo .ht-app { border:1px solid var(--mv-border); border-radius:var(--mv-radius-xl); background:var(--mv-surface); box-shadow:var(--mv-shadow-sm); overflow:hidden }
    #ht-demo .ht-bar { display:flex; align-items:center; gap:1rem; height:3.5rem; padding:0 1rem 0 1.125rem; border-bottom:1px solid var(--mv-border) }
    #ht-demo .ht-brand { display:flex; align-items:center; gap:.5rem; font-weight:650; font-size:.9375rem; letter-spacing:-.01em }
    #ht-demo .ht-logo { display:grid; place-items:center; width:1.75rem; height:1.75rem; border-radius:var(--mv-radius-md); background:var(--mv-accent); color:var(--mv-fg-on-accent) }
    #ht-demo .ht-logo svg { width:1rem; height:1rem }
    #ht-demo .ht-nav { display:flex; gap:.25rem; margin:0; padding:0; list-style:none }
    #ht-demo .ht-nav a { display:block; padding:.375rem .625rem; border-radius:var(--mv-radius-md); color:var(--mv-fg-muted); font-size:.8125rem; font-weight:500; text-decoration:none }
    #ht-demo .ht-nav a[aria-current] { background:var(--mv-bg-muted); color:var(--mv-fg) }
    #ht-demo .ht-end { display:flex; align-items:center; gap:.75rem; margin-inline-start:auto }
    #ht-demo .ht-me { display:grid; place-items:center; width:2rem; height:2rem; border-radius:50%; background:var(--mv-bg-emphasis); color:var(--mv-fg); font-size:.75rem; font-weight:600 }
    #ht-demo .ht-body { display:grid; grid-template-columns:minmax(0,1fr) 15rem; gap:1rem; padding:1.125rem }
    #ht-demo .ht-card { min-width:0; padding:1rem 1.125rem; border:1px solid var(--mv-border); border-radius:var(--mv-radius-lg); background:var(--mv-bg-subtle) }
    #ht-demo .ht-card h4 { margin:0 0 .25rem; font-size:.875rem }
    #ht-demo .ht-card p { margin:0; color:var(--mv-fg-muted); font-size:.8125rem; line-height:1.5 }
    #ht-demo .ht-rows { display:grid; gap:.5rem; margin-top:.875rem }
    #ht-demo .ht-row { display:flex; align-items:center; justify-content:space-between; gap:.75rem; padding:.5rem .625rem; border:1px solid var(--mv-border); border-radius:var(--mv-radius-md); background:var(--mv-surface); font-size:.8125rem }
    #ht-demo .ht-row span:last-child { color:var(--mv-fg-muted); font-variant-numeric:tabular-nums }
    #ht-demo .ht-controls { display:flex; align-items:center; justify-content:space-between; gap:.75rem 1rem; flex-wrap:wrap; padding:.875rem 1.125rem; border-top:1px solid var(--mv-border); background:var(--mv-bg-subtle) }
    #ht-demo .ht-controls p { margin:0; color:var(--mv-fg-muted); font-size:.75rem; flex:1 1 16rem }
    #ht-demo .ht-actions { display:flex; align-items:center; gap:.5rem; flex-wrap:wrap }
    #ht-demo .ht-log { min-height:1.25rem; margin:0; color:var(--mv-fg-subtle); font:.75rem/1.4 var(--mv-font-mono) }
    #ht-demo .mv-choice { font-size:.8125rem }
    #ht-demo .ht-kiosk { display:flex; align-items:center; gap:1rem; flex-wrap:wrap; padding:1rem 1.125rem; border:1px solid var(--mv-border); border-radius:var(--mv-radius-xl); background:var(--mv-surface); box-shadow:var(--mv-shadow-sm) }
    #ht-demo .ht-kiosk-title { display:grid; gap:.125rem; flex:1 1 14rem; min-width:0 }
    #ht-demo .ht-kiosk-title strong { font-size:.9375rem; letter-spacing:-.01em }
    #ht-demo .ht-kiosk-title span { color:var(--mv-fg-muted); font-size:.8125rem }
    @media (max-width:40rem) {
      #ht-demo .ht-nav { display:none }
      #ht-demo .ht-body { grid-template-columns:minmax(0,1fr) }
    }
  </style>

  <!-- Main: a billing console with a 45-second session (accelerated), alarm in the last 20 seconds -->
  <section class="ht-app" aria-label="Billing console">
    <header class="ht-bar">
      <span class="ht-brand">
        <span class="ht-logo" aria-hidden="true"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M4 7h16v10H4z"/><path d="M4 11h16"/></svg></span>
        Tallypoint
      </span>
      <ul class="ht-nav">
        <li><a href="#" aria-current="page">Invoices</a></li>
        <li><a href="#">Customers</a></li>
        <li><a href="#">Payouts</a></li>
      </ul>
      <span class="ht-end">
        <mv-hatch id="ht-main" duration="45s" warn="20s" channel="ht-demo-session">
          <button slot="expired" type="button" class="mv-button" id="ht-signin">Sign in again</button>
        </mv-hatch>
        <span class="ht-me" aria-hidden="true">MR</span>
      </span>
    </header>
    <div class="ht-body">
      <div class="ht-card">
        <h4>Invoice INV-2048 · Draft</h4>
        <p>Acme Traders · due Oct 15, 2026. Unsaved edits are at risk if the session ends.</p>
        <div class="ht-rows">
          <div class="ht-row"><span>Annual platform license</span><span>$12,400.00</span></div>
          <div class="ht-row"><span>Onboarding workshop (2 days)</span><span>$3,200.00</span></div>
          <div class="ht-row"><span>Priority support</span><span>$1,800.00</span></div>
        </div>
      </div>
      <div class="ht-card">
        <h4>Keepalive</h4>
        <p>Each reset pings the server before the timer restarts.</p>
        <p class="ht-log" id="ht-log" aria-live="off" style="margin-top:.75rem">Session started.</p>
      </div>
    </div>
    <div class="ht-controls">
      <p>The session lasts 45 seconds here. Open this page in two tabs: extending in one extends both.</p>
      <span class="ht-actions">
        <label class="mv-choice"><input type="checkbox" class="mv-checkbox" id="ht-fail"> Make the keepalive fail</label>
        <button type="button" class="mv-button" data-variant="outline" data-size="sm" id="ht-ff">
          <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="m5 6 7 6-7 6zM13 6l7 6-7 6z"/></svg>
          Fast-forward to alarm
        </button>
        <button type="button" class="mv-button" data-variant="ghost" data-size="sm" id="ht-restart">Restart</button>
      </span>
    </div>
  </section>

  <!-- Kiosk: resetting requires typing a short code -->
  <div class="ht-kiosk">
    <span class="ht-kiosk-title">
      <strong>Front desk kiosk · Terminal 3</strong>
      <span>Shared device: staying signed in requires typing a confirmation code.</span>
    </span>
    <mv-hatch id="ht-kiosk" duration="2m" warn="30s" code="K7M2" label="Kiosk"></mv-hatch>
    <button type="button" class="mv-button" data-variant="outline" data-size="sm" id="ht-kiosk-ff">Fast-forward to alarm</button>
  </div>

  <script type="module">
    const main = document.getElementById("ht-main");
    const kiosk = document.getElementById("ht-kiosk");
    const log = document.getElementById("ht-log");
    const fail = document.getElementById("ht-fail");
    const time = () => new Date().toLocaleTimeString("en-US", { hour: "numeric", minute: "2-digit", second: "2-digit" });
    const say = (text) => { log.textContent = `${time()} · ${text}`; };

    // A fake keepalive endpoint: 600 ms round trip, optionally failing.
    const keepalive = () => new Promise((resolve, reject) => {
      setTimeout(() => (fail.checked ? reject(new Error("503")) : resolve()), 600);
    });

    main.addEventListener("mv-reset", (e) => {
      say(`Keepalive ping (${e.detail.reason})…`);
      e.detail.waitUntil(keepalive().then(() => say("Session extended by 45 s.")));
    });
    main.addEventListener("mv-reset-error", () => say("Keepalive failed: server unavailable."));
    main.addEventListener("mv-alarm", () => say("Alarm: 20 seconds left."));
    main.addEventListener("mv-expire", () => say("Session expired."));
    main.addEventListener("mv-signout", () => say("Signed out."));
    main.addEventListener("mv-sync", () => say("Extended from another tab."));

    document.getElementById("ht-signin").addEventListener("click", () => { main.restart(); say("Signed in again."); });
    document.getElementById("ht-restart").addEventListener("click", () => { main.restart(); say("Session restarted."); });
    document.getElementById("ht-ff").addEventListener("click", () => { main.deadline = Date.now() + 19_500; });
    document.getElementById("ht-kiosk-ff").addEventListener("click", () => {
      if (kiosk.state === "expired" || kiosk.state === "signed-out") kiosk.restart();
      kiosk.deadline = Date.now() + 25_500;
    });
    kiosk.addEventListener("mv-expire", () => setTimeout(() => kiosk.restart(), 4000));
    kiosk.addEventListener("mv-signout", () => setTimeout(() => kiosk.restart(), 4000));
  </script>
</div>

API

Attributes

Name	类型	Default	Description
`duration`	time ("15m", "90s", "1h30m", "500ms", ms number)	`15m`	Session length restored by every reset. The countdown starts on first connection (or from the deadline property if you set it).
`warn`	time	`2m`	Remaining time under which the alarm phase starts: the chip turns amber and beacons, the alarm panel opens, the reset must be deliberate. Clamped to duration.
`code`	string		Confirmation code the user must type (case and spaces ignored) before “Stay signed in” works during the alarm phase. For kiosks and high-security back offices; resetTimer() from code ignores it.
`modal`	boolean		Alarm and expired panels open in a modal `<dialog>` (showModal, backdrop, focus trapped by the browser) instead of the anchored non-modal panel. Escape folds it; the chip stays in alarm.
`sound`	boolean		Soft sine beeps via WebAudio when the alarm starts (2), at 30 s (1) and 10 s (3). Only after the user has interacted with the page (autoplay policy); never otherwise.
`activity-reset`	boolean		Real pointer, key, wheel and scroll activity anywhere in the page silently resets the timer during the calm phase only (throttled to one reset every duration/10, between 5 s and 60 s). Never in the alarm phase: then the reset must be deliberate. Emits mv-reset with reason "activity" so you can ping your keepalive.
`channel`	string		BroadcastChannel name shared by every tab of the same session: a reset (new deadline), an expiry or a sign-out in one tab applies to all of them. Ignored where BroadcastChannel is unsupported.
`label`	string	`Session`	Label shown in the chip before the countdown.
`placement`	bottom-end \| bottom-start \| bottom \| top-end \| top-start \| top	`bottom-end`	Preferred side of the non-modal panel relative to the chip (flips and shifts to stay in the viewport).
`data-state`	active \| alarm \| expired \| signed-out		Set by the component (styleable). data-critical is added in the last 10 seconds, data-pending while a keepalive promise is in flight.

Properties

Name	类型	Description
`deadline`	number (ms epoch) \| Date	Absolute expiry time. Read it, or set it from your server’s real session expiry (also leaves the expired state). Setting it is broadcast to the other tabs.
`remaining`	number (ms)	Time left, recomputed from the deadline on every read (read-only).
`state`	"active" \| "alarm" \| "expired" \| "signed-out"	Current phase (read-only).
`pending`	boolean	True while a reset waits for the promises passed to waitUntil() (read-only).
`strings`	Partial<Record<string, string>>	Overrides for every visible text and announcement (keys: label, activeTitle, activeText, activeTextActivity, alarmTitle, alarmText, expiredTitle, expiredText, signedOutTitle, signedOutText, extend, stay, signOut, signIn, codeLabel ({code}), codeMismatch, error, timer ({time}), announceAlarm, announceLeft, announceExtended, announceRemote, announceExpired, announceSignedOut, expiredChip, signedOutChip). English defaults.

Methods

Name	Description
`resetTimer({ reason? })`	Programmatic keepalive (reason defaults to "api"): emits the cancelable mv-reset, waits for waitUntil promises, applies the new deadline and broadcasts it. Returns Promise`<boolean>` (false if cancelled, failed, already pending or expired).
`expire()`	Forces the expired state now (e.g. the server answered 401); emits mv-expire with reason "api" and broadcasts it.
`restart()`	Starts a brand-new session (after signing in again): fresh deadline, calm phase, panel closed. No mv-reset event.
`open() / close()`	Opens or folds the panel (the calm panel shows the countdown with “Extend session” and “Sign out”).

Events

Name	Description
`mv-reset`	Cancelable, before any reset. detail: { reason: "button" \| "code" \| "activity" \| "api", remaining, waitUntil(promise) }. Call waitUntil() synchronously with your keepalive request: the button shows a busy state, expiry is held while it is in flight, a rejection keeps the old deadline and shows an error; a promise resolving to a Date or epoch ms uses that as the new deadline. preventDefault() refuses the reset.
`mv-reset-error`	A waitUntil promise rejected. detail: { reason, error }.
`mv-alarm`	The alarm phase started. detail: { remaining }.
`mv-expire`	The session is lost. detail: { reason: "timeout" \| "api" \| "remote" } (remote: another tab expired).
`mv-signout`	“Sign out” was chosen (cancelable), or another tab signed out (detail.remote true, not cancelable). detail: { remote }.
`mv-signin`	The default “Sign in again” button of the expired panel was clicked (not emitted when you provide slot="expired" content). Call restart() once signed in.
`mv-sync`	Another tab moved the deadline (reset or server expiry). detail: { deadline }.

Content structure

Name	Description
`expired`	Children with slot="expired" (a sign-in link, a button that opens your login dialog…) replace the default “Sign in again” button in the expired / signed-out panel.

CSS classes

Name	Description
`mv-hatch-chip`	The countdown chip (`<button>` toggling the panel): -chip-icon, -chip-label, .mv-hatch-reel, -chip-end (“Expired”).
`mv-hatch-reel / mv-hatch-cell / mv-hatch-glyph`	Rolling tabular digits: one clipped cell per character, glyphs roll out upward and in from below; separators have data-sep.
`mv-hatch-panel`	Alarm / status panel (Popover API top layer, or inside .mv-hatch-dialog with modal): -head, -icon, -title, -text, -clock (big reel + -meter), -code, -error, -actions, -slot.
`mv-hatch-dialog`	The `<dialog>` used in modal mode (::backdrop styled with --mv-overlay).

CSS variables

Name	Default	Description
`--mv-hatch-warn`	`var(--mv-warning)`	Alarm-phase color: chip tint, beacon, meter, panel ring.
`--mv-hatch-critical`	`var(--mv-danger)`	Color of the last 10 seconds and of the expired state.

Accessibility

The chip is a real <button> (aria-expanded, aria-controls) described by a visually hidden role="timer" element (“14 minutes left in your session”; to the second during the alarm) whose implicit aria-live is off: screen readers read it on demand, it never chatters. Entering the alarm phase is announced once in an assertive live region (“Your session expires in 2 minutes. Choose Stay signed in to keep working.”), then at most at 60 s and 30 s (polite) and 10 s (assertive), skipping milestones already inside a short warn window. Focus moves to “Stay signed in” (or to the code field) when the alarm starts only if the user is not typing in a field and has not pressed a key in the last 1.5 s; otherwise the panel just appears. The panel is a labelled, described non-modal dialog placed right after the chip in the DOM (Tab reaches it naturally); Escape folds it back to the chip, the calm panel also closes on outside click, the alarm panel does not. modal uses a native <dialog> (focus containment, Escape folds it). The code field has a real <label> showing the code, aria-invalid and an error message linked with aria-describedby; Enter submits. While a keepalive is pending the button is aria-busy and aria-disabled; failures are announced assertively. After a reset, focus returns to the chip if it was inside the panel and “Session extended.” is announced politely; expiry is announced assertively and focus moves to the sign-in action (same typing rule). Colors always come with an icon and words (clock / alarm / lock, “Expired”). Reduced motion (OS or data-motion="reduce"): digits change without rolling, the beacon becomes a static ring, the meter jumps instead of sliding. Sound is opt-in and never plays before a user gesture.