swarm-ui: a start page at / and the hive directory at /hives

/ is now the swarm's name over the digital-rain backdrop the hive
dashboard's home has, and the swarm name in the header links to it. The
hive directory moves to /hives, where the nav's hives tab points. The
swarm name is read once per page load by a shared hook, the header and
the start page both use it. Closes #5252

docs/swarm/ui.md

@@ -9,7 +9,8 @@ domain, covers host-level detail for one hive.
 
 | route                                          | what                                                                                                                                   |
 | ---------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- |
-| `/`                                            | the hive directory, each hive with its last reported status                                                                            |
+| `/`                                            | the start page: the swarm's name over a digital-rain backdrop; the swarm name in the header links here                                 |
+| `/hives`                                       | the hive directory, each hive with its last reported status                                                                            |
 | `/agents`                                      | every agent: status, config PR, wanted state, inference settings, resource caps; create agents, link forge, matrix and GitHub accounts |
 | `/agents/<name>/terminal`                      | one agent's live terminal                                                                                                              |
 | `/agents/<name>/subagents/<subagent>/terminal` | one of that agent's subagents' live terminal                                                                                           |

frontend/packages/swarm-ui/src/App.tsx

@@ -11,6 +11,7 @@ import { IssueReportPage } from "./pages/IssueReportPage.js";
 import { ReviewRunsPage } from "./pages/review-runs/ReviewRunsPage.js";
 import { ReviewTryOutPage } from "./pages/review-tryout/ReviewTryOutPage.js";
 import { SchedulesPage } from "./pages/schedules/SchedulesPage.js";
+import { StartPage } from "./pages/StartPage.js";
 import { Panel } from "./ui/panel/Panel.js";
 
 function NotFound() {
@@ -25,7 +26,8 @@ export function App() {
   return (
     <Shell>
       <Switch>
-        <Route path="/" component={HivesPage} />
+        <Route path="/" component={StartPage} />
+        <Route path="/hives" component={HivesPage} />
         <Route path="/agents" component={AgentsPage} />
         <Route path="/agents/:name/terminal" component={AgentTerminalPage} />
         <Route

frontend/packages/swarm-ui/src/pages/HivesPage.tsx

@@ -1,4 +1,4 @@
-// <HivesPage> — the hive roster, `/`'s content. Fetches
+// <HivesPage> — the hive roster, `/hives`' content. Fetches
 // swarm-controller's `GET /api/hives/status`, the swarm-wide status
 // aggregate: one row per roster hive, freshness derived at read time
 // from the status bucket. Supersedes the earlier `GET /api/hives` +

frontend/packages/swarm-ui/src/pages/StartPage.css

@@ -0,0 +1,23 @@
+/* The page fills the full-bleed body; the rain canvas fills the page and the
+ * name sits centred over it. */
+.start-page {
+  position: relative;
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  overflow: hidden;
+}
+.start-page-name {
+  position: relative;
+  margin: 0;
+  padding: 0 1em;
+  text-align: center;
+  font-size: clamp(2em, 8vw, 5em);
+  font-weight: 600;
+  color: var(--purple);
+  text-shadow:
+    0 0 0.4em color-mix(in srgb, var(--purple) 55%, transparent),
+    0 0 1.2em var(--bg);
+}

frontend/packages/swarm-ui/src/pages/StartPage.tsx

@@ -0,0 +1,20 @@
+// <StartPage> — `/`, the swarm's landing page: the swarm's name over the
+// digital-rain backdrop, and nothing else. The header's swarm name links
+// here. The hive roster that used to be `/` is now `/hives`.
+import { MatrixRain } from "../shell/MatrixRain.js";
+import { useSwarmName } from "../shell/useSwarmName.js";
+import "./StartPage.css";
+
+// Same fallback as the header and the page title, so an unnamed swarm shows
+// one label everywhere.
+const DEFAULT_NAME = "hyperhive swarm";
+
+export function StartPage() {
+  const name = useSwarmName() ?? DEFAULT_NAME;
+  return (
+    <div class="start-page">
+      <MatrixRain />
+      <h1 class="start-page-name">{name}</h1>
+    </div>
+  );
+}

frontend/packages/swarm-ui/src/shell/MatrixRain.css

@@ -0,0 +1,9 @@
+/* Fills the nearest positioned ancestor, dimmed so it reads as backdrop. */
+.matrix-rain {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  height: 100%;
+  opacity: 0.32;
+  pointer-events: none;
+}

frontend/packages/swarm-ui/src/shell/MatrixRain.tsx

@@ -0,0 +1,116 @@
+// <MatrixRain> — the falling-glyph "digital rain" backdrop, drawn on a canvas
+// that fills its positioned parent. Purely decorative, so it is hidden from
+// assistive tech and takes no pointer events. The glyphs take the live
+// `--green` and the fade trail the live `--bg`, so a theme swap recolours it.
+// Stepped on an interval (the steppy cadence is the look, and it costs
+// little), paused while the tab is hidden, and not drawn at all under
+// `prefers-reduced-motion`. The same effect as the hive dashboard's home
+// page, which is plain JS over a fixed canvas.
+import { useEffect, useRef } from "preact/hooks";
+import "./MatrixRain.css";
+
+const GLYPHS = "アイウエオカキクケコサシスセソタチツテト0123456789:=*+-<>¦";
+const CELL = 16; // glyph cell size, in px
+const STEP_MS = 55;
+
+// `getComputedStyle` on a custom property returns its declared value
+// unresolved (`var(--x)`), so resolve a concrete rgb() by computing a real
+// `color` on a probe element instead.
+function resolveColor(varName: string, fallback: string): string {
+  const probe = document.createElement("span");
+  probe.style.color = `var(${varName})`;
+  probe.style.display = "none";
+  document.body.appendChild(probe);
+  const c = getComputedStyle(probe).color;
+  probe.remove();
+  return /^rgb/.test(c) ? c : fallback;
+}
+
+export function MatrixRain() {
+  const ref = useRef<HTMLCanvasElement | null>(null);
+
+  useEffect(() => {
+    const canvas = ref.current;
+    const ctx = canvas?.getContext("2d");
+    if (!canvas || !ctx) return;
+    if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) return;
+
+    // Resolved again whenever the theme can have changed: the shell applies
+    // its theme override from an effect that runs after this one, and a
+    // later switch from the settings menu changes it too.
+    let glyphColor = "";
+    let fadeColor = "";
+    function resolveColors() {
+      glyphColor = resolveColor("--green", "rgb(166, 227, 161)");
+      // The fade trail is the background at low alpha. Its channels are
+      // pulled out numerically so the trail fades whatever spacing
+      // rgb()/rgba() comes back in, and never fills solid.
+      const bg = resolveColor("--bg", "rgb(30, 30, 46)").match(
+        /(\d+)[^\d]+(\d+)[^\d]+(\d+)/,
+      );
+      fadeColor = bg
+        ? `rgba(${bg[1]}, ${bg[2]}, ${bg[3]}, 0.09)`
+        : "rgba(30, 30, 46, 0.09)";
+    }
+    resolveColors();
+    const themeWatch = new MutationObserver(resolveColors);
+    themeWatch.observe(document.documentElement, { attributes: true });
+    const schemeQuery = window.matchMedia("(prefers-color-scheme: dark)");
+    schemeQuery.addEventListener("change", resolveColors);
+
+    let cols = 0;
+    let drops: number[] = [];
+
+    function resize() {
+      if (!canvas || !ctx) return;
+      canvas.width = canvas.offsetWidth;
+      canvas.height = canvas.offsetHeight;
+      cols = Math.max(1, Math.ceil(canvas.width / CELL));
+      drops = Array.from({ length: cols }, () =>
+        Math.floor(Math.random() * -40),
+      );
+      ctx.font = `${CELL}px monospace`; // a canvas resize resets the font
+    }
+
+    function tick() {
+      if (!canvas || !ctx) return;
+      ctx.fillStyle = fadeColor;
+      ctx.fillRect(0, 0, canvas.width, canvas.height);
+      ctx.fillStyle = glyphColor;
+      for (let i = 0; i < cols; i++) {
+        const ch = GLYPHS[Math.floor(Math.random() * GLYPHS.length)] ?? "0";
+        ctx.fillText(ch, i * CELL, (drops[i] ?? 0) * CELL);
+        if ((drops[i] ?? 0) * CELL > canvas.height && Math.random() > 0.975) {
+          drops[i] = 0;
+        }
+        drops[i] = (drops[i] ?? 0) + 1;
+      }
+    }
+
+    let timer: number | null = null;
+    const play = () => {
+      if (timer === null) timer = window.setInterval(tick, STEP_MS);
+    };
+    const pause = () => {
+      if (timer !== null) {
+        window.clearInterval(timer);
+        timer = null;
+      }
+    };
+    const onVisibility = () => (document.hidden ? pause() : play());
+
+    resize();
+    window.addEventListener("resize", resize);
+    document.addEventListener("visibilitychange", onVisibility);
+    play();
+    return () => {
+      pause();
+      themeWatch.disconnect();
+      schemeQuery.removeEventListener("change", resolveColors);
+      window.removeEventListener("resize", resize);
+      document.removeEventListener("visibilitychange", onVisibility);
+    };
+  }, []);
+
+  return <canvas ref={ref} class="matrix-rain" aria-hidden="true" />;
+}

frontend/packages/swarm-ui/src/shell/Shell.css

@@ -55,6 +55,12 @@
   -webkit-backdrop-filter: blur(8px) saturate(120%);
   backdrop-filter: blur(8px) saturate(120%);
 }
+/* The swarm name links to the start page; the link adds no look of its own,
+   so the brand's accent and glow (on the span inside) are all that show. */
+.shell-brand-link {
+  color: inherit;
+  text-decoration: none;
+}
 .shell-brand {
   font-weight: 600;
   /* Base colour only — Shell.tsx overrides it inline to the same

frontend/packages/swarm-ui/src/shell/Shell.tsx

@@ -36,6 +36,7 @@ import { HideDebugSetting } from "@hive/shared/hide-debug-setting.js";
 import { useApplyThemeOverride } from "@hive/shared/theme-apply.js";
 import { useApplyMotionOverride } from "@hive/shared/motion-apply.js";
 import { useDynamicTabs } from "./useDynamicTabs.js";
+import { useSwarmName } from "./useSwarmName.js";
 import "./Shell.css";
 
 // Storage keys this app owns for `@hive/shared`'s settings mechanism —
@@ -47,7 +48,7 @@ const THEME_KEY = "swarm-ui:theme-override";
 const MOTION_KEY = "swarm-ui:motion-override";
 
 const NAV_ITEMS: { href: string; label: string; accent: string }[] = [
-  { href: "/", label: "hives", accent: "var(--purple)" },
+  { href: "/hives", label: "hives", accent: "var(--purple)" },
   { href: "/agents", label: "agents", accent: "var(--green)" },
   { href: "/jobs", label: "jobs", accent: "var(--pink)" },
   { href: "/schedules", label: "schedules", accent: "var(--cyan)" },
@@ -79,8 +80,10 @@ const WIDE_BODY_ROUTES = new Set([
 const FULL_BLEED_ROUTE_PATTERN =
   /^\/agents\/[^/]+(\/subagents\/[^/]+)?\/terminal$/;
 
+// The start page (`/`) is full-bleed too: its rain backdrop fills the whole
+// body below the header.
 function isFullBleedRoute(location: string): boolean {
-  return FULL_BLEED_ROUTE_PATTERN.test(location);
+  return location === "/" || FULL_BLEED_ROUTE_PATTERN.test(location);
 }
 
 function isWideBodyRoute(location: string): boolean {
@@ -206,7 +209,7 @@ function DynamicTabLink({
 }
 
 export function Shell({ children }: { children: ComponentChildren }) {
-  const [swarmName, setSwarmName] = useState<string | null>(null);
+  const swarmName = useSwarmName();
   const [location] = useLocation();
   const navRef = useRef<HTMLElement | null>(null);
   const textRefs = useRef<Record<string, HTMLSpanElement | null>>({});
@@ -340,23 +343,8 @@ export function Shell({ children }: { children: ComponentChildren }) {
     setIndicator(measureIndex(settledIndexRef.current));
   }, [tabs.length]);
 
-  // Fetched once here, not per-page: every route mounts inside one
+  // `swarmName` stays `null` on a failed fetch or an unconfigured name, and
-  // `<Shell>`, and the swarm's name doesn't change within a page
+  // the header/title fall back to `DEFAULT_BRAND`; see `useSwarmName`.
-  // visit. A fetch failure is silently ignored — `swarmName` just stays
-  // `null` and the header/title fall back to `DEFAULT_BRAND`, same as
-  // an operator who never configured a name; this label is cosmetic,
-  // not worth an `ApiErrorPanel`.
-  useEffect(() => {
-    (async () => {
-      const r = await fetch("/api/swarm");
-      if (!r.ok) return;
-      const data = (await r.json()) as { name: string | null };
-      if (data.name) setSwarmName(data.name);
-    })().catch(() => {
-      /* cosmetic only — see comment above */
-    });
-  }, []);
-
   const brand = swarmName ?? DEFAULT_BRAND;
   // Per-route label so browser tabs of different pages tell apart: a
   // top-level route takes its nav label, a terminal route takes the
@@ -378,20 +366,22 @@ export function Shell({ children }: { children: ComponentChildren }) {
   return (
     <div class={"shell" + (isFullBleedRoute(location) ? " shell-full" : "")}>
       <header class="shell-header">
-        <span
+        <Link href="/" class="shell-brand-link">
-          class="shell-brand"
+          <span
-          // Same glow recipe as the active nav tab / panel titles, riding
+            class="shell-brand"
-          // `navAccent` — the same value `color` already uses here — so
+            // Same glow recipe as the active nav tab / panel titles, riding
-          // the brand's glow tracks the identical hop sequence as its own
+            // `navAccent` — the same value `color` already uses here — so
-          // text colour instead of introducing a second, disagreeing
+            // the brand's glow tracks the identical hop sequence as its own
-          // accent source.
+            // text colour instead of introducing a second, disagreeing
-          style={{
+            // accent source.
-            color: navAccent,
+            style={{
-            textShadow: `0 0 8px color-mix(in srgb, ${navAccent} 45%, transparent)`,
+              color: navAccent,
-          }}
+              textShadow: `0 0 8px color-mix(in srgb, ${navAccent} 45%, transparent)`,
-        >
+            }}
-          {brand}
+          >
-        </span>
+            {brand}
+          </span>
+        </Link>
         <nav class="shell-nav" ref={navRef}>
           {NAV_ITEMS.map((item) => (
             <NavLink

frontend/packages/swarm-ui/src/shell/useSwarmName.ts

@@ -0,0 +1,36 @@
+// useSwarmName — the swarm's configured display name from `GET /api/swarm`,
+// or `null` until it arrives, when none is configured, or when the fetch
+// fails. The label is cosmetic, so a failure is swallowed rather than shown:
+// callers fall back to their own default, as an operator who never set a
+// name sees. One request per page load, shared by every caller, because the
+// header and the start page both ask for it and the name does not change
+// within a visit.
+import { useEffect, useState } from "preact/hooks";
+
+let pending: Promise<string | null> | null = null;
+
+function fetchSwarmName(): Promise<string | null> {
+  if (pending === null) {
+    pending = (async () => {
+      const r = await fetch("/api/swarm");
+      if (!r.ok) return null;
+      const data = (await r.json()) as { name: string | null };
+      return data.name || null;
+    })().catch(() => null);
+  }
+  return pending;
+}
+
+export function useSwarmName(): string | null {
+  const [name, setName] = useState<string | null>(null);
+  useEffect(() => {
+    let cancelled = false;
+    void fetchSwarmName().then((n) => {
+      if (!cancelled && n !== null) setName(n);
+    });
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+  return name;
+}