feat(ui): rewrite Tabs onto wire classes with URL sync and roving focus

Tabs was the only component in the library styled with Tailwind utilities, so
it could not be themed like the rest and assumed Tailwind was present. It also
fired raw CustomEvents instead of declaring outputs, and set a roving tabindex
with no keydown handler at all -- which left every inactive tab unreachable by
Tab while the arrows did nothing.

It now uses wire-* classes and a local style block, declares change and select
outputs, and opts into the roving runtime.

mode=url mirrors the selection into a query parameter via pushState. Back and
forward are handled in the runtime, which activates the matching tab rather
than assigning to component state: a popstate listener writing state would be
writing after the client function returned, and that write is dropped. The
round trip is marked so the component does not push a second history entry for
a navigation that came from history.

Also anchors Nav submenus so the viewport clamp can pull them back on screen.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/ui/components/Nav.wrn

@@ -106,7 +106,11 @@ component Nav {
               >&#8250;</span>
             </a>
 
-            <ul class="wire-nav__submenu" data-show="childrenOf(item).length > 0">
+            <ul
+              class="wire-nav__submenu"
+              data-wrn-anchored="true"
+              data-show="childrenOf(item).length > 0"
+            >
               {#each childrenOf(item) as child}
                 <li class="wire-nav__item" data-has-children='{childrenOf(child).length > 0}'>
                   <a
@@ -133,6 +137,7 @@ component Nav {
 
                   <ul
                     class="wire-nav__submenu wire-nav__submenu--level3"
+                    data-wrn-anchored="true"
                     data-show="childrenOf(child).length > 0"
                   >
                     {#each childrenOf(child) as leaf}

packages/ui/components/Tabs.wrn

@@ -1,90 +1,318 @@
+// Tabs -- a tablist over panels.
+//
+//   <Tabs items='[{"label":"Overview","value":"overview"}]' active="overview" />
+//
+// With mode="url" the selection is mirrored into a query parameter using
+// history.pushState, so the panel swaps without a page load and the back
+// button works. The query parameter is used rather than the hash because it
+// survives a reload and does not collide with in-page anchors or Scrollspy.
+//
+// NOTE: the style block uses /* */ comments only -- // is not a CSS comment
+// and silently swallows the rule that follows it.
 component Tabs {
+  outputs {
+    change(payload: { value: string; item: object; index: number })
+    select(payload: { value: string; item: object; index: number })
+  }
+
   props {
-    size: string = "default"
     color: string = "primary"
-    label: string = "Tabs"
+    size: string = "default"
     items: unknown[] = []
     active: string = ""
     orientation: string = "horizontal"
+    mode: string = "client"
+    param: string = "tab"
+    label: string = "Tabs"
     class: string = ""
   }
 
-  state activeValue = active || (items[0] ? (items[0].value || items[0].id || "0") : "")
+  state activeValue = ""
+
+  functions {
+    shared function itemList() {
+      return Array.isArray(items) ? items : []
+    }
+
+    shared function valueOf(item, index) {
+      return String(item.value || item.id || index)
+    }
+
+    shared function currentValue() {
+      if (activeValue) {
+        return activeValue
+      }
+      if (active) {
+        return active
+      }
+      var list = itemList()
+      return list.length ? valueOf(list[0], 0) : ""
+    }
+
+    shared function isSelected(item, index) {
+      return valueOf(item, index) === currentValue()
+    }
+
+    shared function rovingAxis() {
+      return orientation === "vertical" ? "vertical" : "horizontal"
+    }
+
+    client function selectTab(item, index, sourceEvent) {
+      if (item.disabled) {
+        return
+      }
+      var value = valueOf(item, index)
+      activeValue = value
+
+      // A click that came from the back button must not push another entry.
+      var target = sourceEvent ? sourceEvent.currentTarget : null
+      var group = target && target.closest ? target.closest("[data-wrn-tabs-param]") : null
+      var restoring = group && group.getAttribute("data-wrn-tabs-restoring") === "true"
+
+      if (mode === "url" && !restoring && window.history && window.history.pushState) {
+        var url = new URL(window.location.href)
+        url.searchParams.set(param || "tab", value)
+        window.history.pushState({}, "", url.toString())
+      }
+
+      output.change({ value: value, item: item, index: index })
+      output.select({ value: value, item: item, index: index })
+    }
+  }
 
   view {
     <section
+      {...attrs}
       data-ui-component="Tabs"
-      class='w-full {class}'
-      class:flex='orientation === "vertical"'
-      class:items-start='orientation === "vertical"'
-      class:gap-6='orientation === "vertical"'
+      class='wire-tabs {class}'
+      data-orientation='{orientation}'
+      data-color='{color}'
+      data-size='{size}'
+      data-mode='{mode}'
+      data-param='{param}'
+      data-wrn-tabs-param='{mode === "url" ? param : ""}'
     >
       <div
+        class="wire-tabs__list"
         role="tablist"
         aria-label='{label}'
         aria-orientation='{orientation}'
-        class="flex min-w-0 gap-1 overflow-x-auto rounded-xl border border-[var(--wire-color-border)] bg-[var(--wire-color-surface-soft)] p-1"
-        class:flex-col='orientation === "vertical"'
-        class:w-56='orientation === "vertical"'
-        class:shrink-0='orientation === "vertical"'
+        data-wrn-roving='{rovingAxis()}'
       >
-        {#each items as item, index}
+        {#each itemList() as item, index}
           <button
             type="button"
+            class="wire-tabs__tab"
             role="tab"
-            id='tab-{item.value || item.id || index}'
-            aria-selected='{activeValue === (item.value || item.id || String(index))}'
-            aria-controls='panel-{item.value || item.id || index}'
-            tabindex='{activeValue === (item.value || item.id || String(index)) ? "0" : "-1"}'
-            disabled='{item.disabled || false}'
-            class="inline-flex min-w-max flex-1 items-center justify-center gap-2 rounded-lg px-4 py-2.5 text-sm font-semibold outline-none transition disabled:cursor-not-allowed disabled:opacity-50"
-            class:bg-[var(--wire-color-surface-raised)]='activeValue === (item.value || item.id || String(index))'
-            class:text-[var(--wire-color-primary)]='activeValue === (item.value || item.id || String(index))'
-            class:shadow-sm='activeValue === (item.value || item.id || String(index))'
-            class:text-[var(--wire-color-text-muted)]='activeValue !== (item.value || item.id || String(index))'
-            class:hover:text-[var(--wire-color-text)]='activeValue !== (item.value || item.id || String(index))'
-            class:justify-start='orientation === "vertical"'
-            class:px-3='size === "sm"'
-            class:py-2='size === "sm"'
-            class:px-5='size === "lg"'
-            class:py-3='size === "lg"'
-            @click='activeValue = item.value || item.id || String(index); event.currentTarget.dispatchEvent(new CustomEvent("change", { bubbles: true, detail: { item: item, index: index, value: activeValue } })); event.currentTarget.dispatchEvent(new CustomEvent("select", { bubbles: true, detail: { item: item, index: index, value: activeValue } }))'
+            data-value='{valueOf(item, index)}'
+            data-wrn-roving-item="true"
+            id='wire-tab-{valueOf(item, index)}'
+            aria-controls='wire-panel-{valueOf(item, index)}'
+            aria-selected='{isSelected(item, index) ? "true" : "false"}'
+            aria-disabled='{item.disabled ? "true" : "false"}'
+            @click='selectTab(item, index, event)'
           >
-            {#if item.icon}
-              <span class='{item.icon + " size-4"}' aria-hidden="true"></span>
-            {/if}
-            <span>{item.label || item.title}</span>
-            {#if item.badge}
-              <span class="rounded-full bg-[var(--wire-color-primary-soft)] px-2 py-0.5 text-xs text-[var(--wire-color-primary)]">{item.badge}</span>
-            {/if}
+            <span class='wire-tabs__icon {item.icon}' data-show="item.icon" aria-hidden="true"></span>
+            <span class="wire-tabs__label">{item.label || item.title}</span>
+            <span class="wire-tabs__badge" data-show="item.badge">{item.badge}</span>
           </button>
         {/each}
       </div>
 
-      <div class="min-w-0 flex-1 pt-4" class:pt-0='orientation === "vertical"'>
-        {#each items as item, index}
+      <div class="wire-tabs__panels">
+        {#each itemList() as item, index}
           <div
+            class="wire-tabs__panel"
             role="tabpanel"
-            id='panel-{item.value || item.id || index}'
-            aria-labelledby='tab-{item.value || item.id || index}'
+            id='wire-panel-{valueOf(item, index)}'
+            aria-labelledby='wire-tab-{valueOf(item, index)}'
             tabindex="0"
-            data-show='activeValue === (item.value || item.id || String(index))'
-            class="rounded-xl outline-none focus-visible:ring-2 focus-visible:ring-[var(--wire-color-focus)]"
+            data-show='isSelected(item, index)'
           >
-            {#if item.title && item.title !== item.label}
-              <h3 class="text-lg font-bold text-[var(--wire-color-text)]">{item.title}</h3>
-            {/if}
-            {#if item.description}
-              <p class="mt-2 leading-7 text-[var(--wire-color-text-muted)]">{item.description}</p>
-            {/if}
-            {#if item.content}
-              <div class="mt-4 text-[var(--wire-color-text)]">{item.content}</div>
-            {/if}
+            <h3 class="wire-tabs__title" data-show="item.title && item.title !== item.label">
+              {item.title}
+            </h3>
+            <p class="wire-tabs__description" data-show="item.description">{item.description}</p>
+            <div class="wire-tabs__content" data-show="item.content">{item.content}</div>
+            <slot name="panel-{valueOf(item, index)}"></slot>
           </div>
         {/each}
-
-        <slot></slot>
+        <slot />
       </div>
     </section>
   }
+
+  style {
+    .wire-tabs {
+      --tabs-accent: var(--wire-color-primary);
+      display: flex;
+      flex-direction: column;
+      gap: 1rem;
+      max-width: 100%;
+    }
+
+    .wire-tabs[data-color="secondary"] {
+      --tabs-accent: var(--wire-color-secondary);
+    }
+
+    .wire-tabs[data-color="success"] {
+      --tabs-accent: var(--wire-color-success);
+    }
+
+    .wire-tabs[data-color="danger"] {
+      --tabs-accent: var(--wire-color-danger);
+    }
+
+    .wire-tabs[data-color="info"] {
+      --tabs-accent: var(--wire-color-info);
+    }
+
+    .wire-tabs[data-size="sm"] {
+      font-size: 0.82rem;
+    }
+
+    .wire-tabs[data-size="lg"] {
+      font-size: 1rem;
+    }
+
+    .wire-tabs[data-orientation="vertical"] {
+      flex-direction: row;
+      align-items: flex-start;
+    }
+
+    .wire-tabs__list {
+      display: flex;
+      gap: 0.25rem;
+      min-width: 0;
+      padding: 0.25rem;
+      border: 1px solid var(--wire-color-border);
+      border-radius: var(--wire-radius-md);
+      background: var(--wire-color-surface-soft);
+      /* A long tablist scrolls rather than wrapping into an unusable stack. */
+      overflow-x: auto;
+    }
+
+    .wire-tabs[data-orientation="vertical"] .wire-tabs__list {
+      flex-direction: column;
+      flex: 0 0 auto;
+      width: 14rem;
+      overflow-x: visible;
+    }
+
+    .wire-tabs__tab {
+      appearance: none;
+      display: inline-flex;
+      align-items: center;
+      justify-content: center;
+      gap: 0.4rem;
+      flex: 1 0 auto;
+      padding: 0.55rem 0.9rem;
+      border: 0;
+      border-radius: var(--wire-radius-sm);
+      background: transparent;
+      color: var(--wire-color-text-muted);
+      font: inherit;
+      font-size: 0.88rem;
+      font-weight: 600;
+      white-space: nowrap;
+      cursor: pointer;
+      transition:
+        background 160ms ease,
+        color 160ms ease;
+    }
+
+    .wire-tabs[data-orientation="vertical"] .wire-tabs__tab {
+      justify-content: flex-start;
+    }
+
+    .wire-tabs__tab:hover {
+      color: var(--wire-color-text);
+    }
+
+    .wire-tabs__tab:focus-visible {
+      outline: 2px solid var(--tabs-accent);
+      outline-offset: 2px;
+    }
+
+    .wire-tabs__tab[aria-selected="true"] {
+      background: var(--wire-color-surface);
+      color: var(--tabs-accent);
+      box-shadow: var(--wire-shadow-1);
+    }
+
+    .wire-tabs__tab[aria-disabled="true"] {
+      opacity: 0.5;
+      pointer-events: none;
+    }
+
+    .wire-tabs__badge {
+      padding: 0.05rem 0.4rem;
+      border-radius: 999px;
+      background: color-mix(in srgb, var(--tabs-accent) 16%, transparent);
+      color: var(--tabs-accent);
+      font-size: 0.72rem;
+    }
+
+    .wire-tabs__panels {
+      min-width: 0;
+      flex: 1 1 auto;
+    }
+
+    .wire-tabs__panel {
+      outline: none;
+      animation: wire-tabs-in 200ms ease both;
+    }
+
+    .wire-tabs__panel:focus-visible {
+      outline: 2px solid var(--tabs-accent);
+      outline-offset: 4px;
+      border-radius: var(--wire-radius-sm);
+    }
+
+    .wire-tabs__title {
+      margin: 0 0 0.35rem;
+      font-size: 1rem;
+      font-weight: 700;
+    }
+
+    .wire-tabs__description {
+      margin: 0;
+      color: var(--wire-color-text-muted);
+      line-height: 1.6;
+    }
+
+    .wire-tabs__content {
+      margin-top: 0.6rem;
+    }
+
+    @keyframes wire-tabs-in {
+      from {
+        opacity: 0;
+        transform: translateY(4px);
+      }
+      to {
+        opacity: 1;
+        transform: none;
+      }
+    }
+
+    /* Respect a reduced-motion preference: swap instantly instead. */
+    @media (prefers-reduced-motion: reduce) {
+      .wire-tabs__panel {
+        animation: none;
+      }
+    }
+
+    @media (max-width: 639px) {
+      .wire-tabs[data-orientation="vertical"] {
+        flex-direction: column;
+      }
+
+      .wire-tabs[data-orientation="vertical"] .wire-tabs__list {
+        width: 100%;
+        flex-direction: row;
+        overflow-x: auto;
+      }
+    }
+  }
 }

packages/ui/test/ui.test.ts

@@ -2614,3 +2614,76 @@ test("nav renders its shell with no items and rejects a non-array", async () =>
     "Expected an array prop",
   );
 });
+
+test("nav submenus are anchored so the viewport clamp can pull them back", async () => {
+  const source = readFileSync(uiComponentPath("Nav"), "utf8");
+  const html = await renderComponent(source, {
+    items: [
+      {
+        label: "Products",
+        value: "products",
+        items: [{ label: "Overview", href: "/p", value: "p" }],
+      },
+    ],
+    active: "p",
+  });
+  const dom = mountHtml(html);
+  // visibility:hidden keeps layout, so the clamp can place a submenu correctly
+  // before it is ever shown -- which is why CSS-driven hover still composes
+  // with the runtime clamp.
+  expect(dom.querySelectorAll(".wire-nav__submenu[data-wrn-anchored]").length).toBeGreaterThan(0);
+});
+
+test("tabs use wire classes and declare real outputs instead of raw events", async () => {
+  const source = readFileSync(uiComponentPath("Tabs"), "utf8");
+  // The whole point of the rewrite: themeable wire-* classes, not Tailwind.
+  expect(source).toContain("outputs {");
+  expect(source).toContain("output.change(");
+  expect(source).not.toContain("new CustomEvent(");
+
+  const html = await renderComponent(source, {
+    items: [
+      { label: "Overview", value: "overview", content: "First panel" },
+      { label: "Pricing", value: "pricing", content: "Second panel" },
+    ],
+    active: "overview",
+  });
+  const dom = mountHtml(html);
+
+  const list = dom.querySelector('[role="tablist"]') as HTMLElement;
+  expect(list.getAttribute("data-wrn-roving")).toBe("horizontal");
+  const tabs = dom.querySelectorAll('[role="tab"]');
+  expect(tabs).toHaveLength(2);
+  expect(tabs[0]!.getAttribute("aria-selected")).toBe("true");
+  expect(tabs[1]!.getAttribute("aria-selected")).toBe("false");
+  expect(dom.querySelector(".wire-tabs")).not.toBeNull();
+  expect(dom.querySelectorAll('[role="tabpanel"]')).toHaveLength(2);
+});
+
+test("tabs in url mode declare the query parameter they sync to", async () => {
+  const source = readFileSync(uiComponentPath("Tabs"), "utf8");
+  const html = await renderComponent(source, {
+    items: [
+      { label: "One", value: "one" },
+      { label: "Two", value: "two" },
+    ],
+    active: "one",
+    mode: "url",
+    param: "tab",
+  });
+  const dom = mountHtml(html);
+  const root = dom.querySelector(".wire-tabs") as HTMLElement;
+  expect(root.getAttribute("data-mode")).toBe("url");
+  expect(root.getAttribute("data-param")).toBe("tab");
+});
+
+test("tabs vertical orientation switches the roving axis", async () => {
+  const source = readFileSync(uiComponentPath("Tabs"), "utf8");
+  const html = await renderComponent(source, {
+    items: [{ label: "One", value: "one" }],
+    active: "one",
+    orientation: "vertical",
+  });
+  const dom = mountHtml(html);
+  expect(dom.querySelector('[role="tablist"]')!.getAttribute("data-wrn-roving")).toBe("vertical");
+});