diff --git a/packages/ui/src/components/spinner-variants.test.ts b/packages/ui/src/components/spinner-variants.test.ts
new file mode 100644
index 00000000000..3915cc85da6
--- /dev/null
+++ b/packages/ui/src/components/spinner-variants.test.ts
@@ -0,0 +1,32 @@
+import { expect, test } from "bun:test"
+import { spinnerDots, spinnerKeyframes, spinnerVariants } from "./spinner-variants"
+
+test("every variation's dots fit the viewBox and light within one loop", () => {
+  Object.values(spinnerVariants).forEach((variant) => {
+    const dots = spinnerDots(variant)
+
+    expect(dots.length).toBe(variant.layout === "orb" ? 37 : variant.span ** 2)
+    dots.forEach((dot) => {
+      expect(dot.x).toBeGreaterThanOrEqual(0)
+      expect(dot.x + dot.size).toBeLessThanOrEqual(16)
+      expect(dot.at).toBeGreaterThanOrEqual(0)
+      expect(dot.at).toBeLessThan(1)
+      expect(dot.still).toBeGreaterThanOrEqual(variant.dim)
+      expect(dot.still).toBeLessThanOrEqual(1)
+    })
+  })
+})
+
+test("a border snake rests its middle dots and visits each edge dot once", () => {
+  const dots = spinnerDots(spinnerVariants.snake)
+  const edge = dots.filter((dot) => !dot.hold)
+
+  expect(dots.filter((dot) => dot.hold === "rest")).toHaveLength(4)
+  expect(new Set(edge.map((dot) => dot.at)).size).toBe(12)
+})
+
+test("keyframes run from the dim rest to fully lit", () => {
+  expect(spinnerKeyframes("spinner-radar", spinnerVariants.radar)).toBe(
+    "@keyframes spinner-radar{0%{opacity:0.2;animation-timing-function:cubic-bezier(.45,0,.2,1)}3%{opacity:1;animation-timing-function:cubic-bezier(.45,0,.2,1)}51%{opacity:0.2;animation-timing-function:cubic-bezier(.45,0,.2,1)}100%{opacity:0.2;animation-timing-function:cubic-bezier(.45,0,.2,1)}}",
+  )
+})
diff --git a/packages/ui/src/components/spinner-variants.ts b/packages/ui/src/components/spinner-variants.ts
new file mode 100644
index 00000000000..0a2021f3923
--- /dev/null
+++ b/packages/ui/src/components/spinner-variants.ts
@@ -0,0 +1,320 @@
+// Dot-matrix variations of the activity spinner, tried from Knobs → Experiments → "Activity spinner". Each variation
+// is plain data: a dot layout, a keyframe shape, and a pattern that turns each dot's place (angle, distance, path
+// index…) into its animation delay. Animation is CSS only; every dot shares the variation's loop, so pinning start
+// times with syncSpinPhase keeps every spinner on screen in phase. Paste replacements from the prototype's
+// "Try in app" list.
+
+export type SpinnerPattern =
+  | "sweep"
+  | "bar"
+  | "diagonal"
+  | "ripple"
+  | "twinkle"
+  | "border"
+  | "breathe"
+  | "spiral"
+  | "rain"
+  | "pulse"
+
+export type SpinnerVariant = {
+  label: string
+  /** "grid" is span × span; "orb" is the 37-dot circle (rows of 3, 5, 7, 7, 7, 5, 3). */
+  layout: "grid" | "orb"
+  span: number
+  /** Dot side and gap, in a 16-unit viewBox. */
+  dot: number
+  gap: number
+  /** Seconds per loop at 1×. */
+  loop: number
+  pattern: SpinnerPattern
+  /** How far apart neighbouring dots light, for the patterns that spread outward. */
+  spread?: number
+  /** The centre dot stays lit (radars and scan lines). */
+  steady?: boolean
+  /** Resting opacity of an unlit dot. */
+  dim: number
+  /** The keyframe shape: [percent of the loop, level from 0 (dim) to 1 (lit)]. */
+  stops: readonly (readonly [number, number])[]
+}
+
+export const spinnerVariants = {
+  radar: {
+    label: "Soft Radar",
+    layout: "grid",
+    span: 5,
+    dot: 2,
+    gap: 1,
+    loop: 1.8,
+    pattern: "sweep",
+    steady: true,
+    dim: 0.2,
+    stops: [
+      [0, 0],
+      [3, 1],
+      [51, 0],
+      [100, 0],
+    ],
+  },
+  orbRadar: {
+    label: "Orb Radar",
+    layout: "orb",
+    span: 7,
+    dot: 1.5,
+    gap: 0.72,
+    loop: 2.2,
+    pattern: "sweep",
+    steady: true,
+    dim: 0.2,
+    stops: [
+      [0, 0],
+      [3, 1],
+      [62, 0],
+      [100, 0],
+    ],
+  },
+  ripple: {
+    label: "Centre Ripple",
+    layout: "grid",
+    span: 5,
+    dot: 2,
+    gap: 1,
+    loop: 1.5,
+    pattern: "ripple",
+    spread: 0.28,
+    dim: 0.2,
+    stops: [
+      [0, 0],
+      [3, 1],
+      [37, 0],
+      [100, 0],
+    ],
+  },
+  snake: {
+    label: "Border Snake",
+    layout: "grid",
+    span: 4,
+    dot: 2.6,
+    gap: 1.3,
+    loop: 1.2,
+    pattern: "border",
+    dim: 0.2,
+    stops: [
+      [0, 0],
+      [3, 1],
+      [33, 0],
+      [100, 0],
+    ],
+  },
+  spiral: {
+    label: "Spiral Fill",
+    layout: "grid",
+    span: 5,
+    dot: 2,
+    gap: 1,
+    loop: 3,
+    pattern: "spiral",
+    dim: 0.2,
+    stops: [
+      [0, 0],
+      [3, 1],
+      [48, 1],
+      [54, 0],
+      [100, 0],
+    ],
+  },
+  breathe: {
+    label: "Breathing Grid",
+    layout: "grid",
+    span: 3,
+    dot: 3.6,
+    gap: 2,
+    loop: 2,
+    pattern: "breathe",
+    spread: 0.05,
+    dim: 0.2,
+    stops: [
+      [0, 0],
+      [8, 0],
+      [50, 1],
+      [92, 0],
+      [100, 0],
+    ],
+  },
+} satisfies Record<string, SpinnerVariant>
+
+export type SpinnerDot = {
+  x: number
+  y: number
+  size: number
+  /** Where in the loop the dot lights, 0–1. */
+  at: number
+  /** The dot's loop as a multiple of the variation's (twinkle varies it). */
+  scale: number
+  /** Always lit, or never animated (the resting middle of a border pattern). */
+  hold?: "lit" | "rest"
+  /** Opacity for reduced motion: the pattern frozen a fifth of the way into its loop. */
+  still: number
+}
+
+type Cell = { c: number; r: number; gx: number; gy: number }
+
+/** The dots of a variation, positioned in a 16-unit viewBox. */
+export function spinnerDots(variant: SpinnerVariant): SpinnerDot[] {
+  const cells = variant.layout === "orb" ? orb() : grid(variant.span)
+  const extent = variant.span * variant.dot + (variant.span - 1) * variant.gap
+  const fit = Math.min(1, 15 / extent)
+  const size = variant.dot * fit
+  const pitch = (variant.dot + variant.gap) * fit
+  const order = variant.pattern === "spiral" ? spiralOrder(variant.span) : []
+  const ring = variant.pattern === "border" ? borderOrder(variant.span) : []
+  const random = seeded(4242)
+  const offsets = Array.from({ length: variant.span }, () => random())
+
+  return cells.map((cell, index) => {
+    const centre = cell.gx === 0 && cell.gy === 0
+
+    const twinkle =
+      variant.pattern === "twinkle" ? { at: random(), scale: [1, 1.35, 1.7][Math.floor(random() * 3)]! } : undefined
+
+    const at = (() => {
+      const spread = variant.spread ?? 1
+      const dist = Math.hypot(cell.gx, cell.gy)
+
+      switch (variant.pattern) {
+        case "sweep":
+          return angle(cell)
+        case "bar":
+          return frac(angle(cell) * 2)
+        case "diagonal":
+          return (cell.c + cell.r) / (2 * variant.span - 1)
+        case "ripple":
+        case "breathe":
+        case "pulse":
+          return frac(dist * spread)
+        case "twinkle":
+          return twinkle!.at
+        case "border":
+          return Math.max(0, ring.indexOf(cell.r * variant.span + cell.c)) / ring.length
+        case "spiral":
+          return order.indexOf(cell.r * variant.span + cell.c) / (2 * order.length)
+        case "rain":
+          return frac(offsets[cell.c]! + cell.r * spread * 0.11)
+      }
+    })()
+
+    const hold =
+      variant.steady && centre
+        ? "lit"
+        : variant.pattern === "border" && !ring.includes(cell.r * variant.span + cell.c)
+          ? "rest"
+          : undefined
+
+    const level = hold === "lit" ? 1 : hold === "rest" ? 0 : levelAt(variant.stops, frac(0.22 - at) * 100)
+
+    return {
+      x: round(8 + cell.gx * pitch - size / 2),
+      y: round(8 + cell.gy * pitch - size / 2),
+      size: round(size),
+      at: round(at),
+      scale: twinkle?.scale ?? 1,
+      hold,
+      still: round(variant.dim + (1 - variant.dim) * level),
+    }
+  })
+}
+
+/** The variation's keyframes, named `name`. */
+export function spinnerKeyframes(name: string, variant: SpinnerVariant) {
+  const frames = variant.stops
+    .map(
+      ([percent, level]) =>
+        `${round(percent)}%{opacity:${round(variant.dim + (1 - variant.dim) * level)};animation-timing-function:cubic-bezier(.45,0,.2,1)}`,
+    )
+    .join("")
+
+  return `@keyframes ${name}{${frames}}`
+}
+
+function grid(span: number): Cell[] {
+  return Array.from({ length: span * span }, (_, index) => {
+    const c = index % span
+    const r = Math.floor(index / span)
+
+    return { c, r, gx: c - (span - 1) / 2, gy: r - (span - 1) / 2 }
+  })
+}
+
+function orb(): Cell[] {
+  return [3, 5, 7, 7, 7, 5, 3].flatMap((count, r) =>
+    Array.from({ length: count }, (_, j) => {
+      const c = (7 - count) / 2 + j
+
+      return { c, r, gx: c - 3, gy: r - 3 }
+    }),
+  )
+}
+
+// Clockwise from the top-left corner, as indices into a span × span grid.
+function borderOrder(span: number) {
+  const top = Array.from({ length: span }, (_, c) => c)
+  const right = Array.from({ length: span - 2 }, (_, r) => (r + 1) * span + span - 1)
+  const bottom = Array.from({ length: span }, (_, c) => (span - 1) * span + span - 1 - c)
+  const left = Array.from({ length: span - 2 }, (_, r) => (span - 2 - r) * span)
+
+  return [...top, ...right, ...bottom, ...left]
+}
+
+// Inward from the top-left corner, clockwise.
+function spiralOrder(span: number) {
+  const order: number[] = []
+  const edges = { top: 0, left: 0, bottom: span - 1, right: span - 1 }
+
+  while (edges.top <= edges.bottom && edges.left <= edges.right) {
+    for (let c = edges.left; c <= edges.right; c++) order.push(edges.top * span + c)
+    edges.top++
+
+    for (let r = edges.top; r <= edges.bottom; r++) order.push(r * span + edges.right)
+    edges.right--
+
+    if (edges.top <= edges.bottom) for (let c = edges.right; c >= edges.left; c--) order.push(edges.bottom * span + c)
+    edges.bottom--
+
+    if (edges.left <= edges.right) for (let r = edges.bottom; r >= edges.top; r--) order.push(r * span + edges.left)
+    edges.left++
+  }
+
+  return order
+}
+
+// Clockwise from 12 o'clock, 0–1.
+function angle(cell: Cell) {
+  return frac(Math.atan2(cell.gx, -cell.gy) / (2 * Math.PI))
+}
+
+function levelAt(stops: SpinnerVariant["stops"], percent: number) {
+  const next = stops.findIndex(([at]) => at >= percent)
+
+  if (next <= 0) return stops[0]?.[1] ?? 0
+  const [p0, l0] = stops[next - 1]!
+  const [p1, l1] = stops[next]!
+
+  return l0 + ((l1 - l0) * (percent - p0)) / (p1 - p0 || 1)
+}
+
+function seeded(seed: number) {
+  const state = { value: seed }
+
+  return () => {
+    state.value = (state.value * 16807) % 2147483647
+
+    return (state.value - 1) / 2147483646
+  }
+}
+
+function frac(value: number) {
+  return value - Math.floor(value)
+}
+
+function round(value: number) {
+  return Math.round(value * 1000) / 1000
+}
diff --git a/packages/ui/src/components/spinner.css b/packages/ui/src/components/spinner.css
index c2652c219d8..ab25a90aaae 100644
--- a/packages/ui/src/components/spinner.css
+++ b/packages/ui/src/components/spinner.css
@@ -32,3 +32,19 @@
     display: block;
   }
 }
+
+/* Dot-matrix variations (Knobs → Experiments → Activity spinner). Each dot rests at its frozen pose, so reduced
+   motion only has to stop the animation. */
+[data-slot="spinner-dots"] rect {
+  opacity: var(--still);
+}
+
+/* syncSpinPhase marks spinners out of view; `!important` beats the inline animation each dot carries. */
+[data-slot="spinner-dots"][data-offscreen] rect {
+  animation-play-state: paused !important;
+}
+
+:root[data-motion="reduce"] [data-slot="spinner-dots"] rect {
+  /* Beats the inline animation each dot carries. */
+  animation: none !important;
+}
diff --git a/packages/ui/src/components/spinner.stories.tsx b/packages/ui/src/components/spinner.stories.tsx
index be6106d1486..c3a32d24b73 100644
--- a/packages/ui/src/components/spinner.stories.tsx
+++ b/packages/ui/src/components/spinner.stories.tsx
@@ -1,36 +1,42 @@
-// @ts-nocheck
-import * as mod from "./spinner"
-import { create } from "../storybook/scaffold"
+import { Spinner, type SpinnerVariantName } from "./spinner"
+import { spinnerVariants } from "./spinner-variants"
 
 const docs = `### Overview
-Animated loading indicator for inline or page-level loading states.
-
-Use with \`Button\` or in empty states.
-
-### API
-- Accepts standard SVG props (class, style).
+Animated loading indicator for inline or page-level loading states. Tabs, \`Loader\`, \`ActivityRing\` and the
+titlebar update button all render it.
 
 ### Variants and states
-- Single default animation style.
+- Today: the 5×5 radar sweep from an animated PNG mask.
+- Dot-matrix variations to try from Knobs → Experiments → Activity spinner; a \`variant\` prop pins one.
 
 ### Behavior
-- Animation is CSS-driven via data attributes.
+- CSS animation only. Every dot of a variation shares one loop, and \`syncSpinPhase\` pins every instance to the
+  same start, so spinners on screen stay in phase.
+- Reduced motion freezes each variation on a still pose.
 
 ### Accessibility
 - Use alongside text or aria-live regions to convey loading state.
-
-### Theming/tokens
-- Uses \`data-component="spinner"\` for styling hooks.
-
 `
 
-const story = create({ title: "UI/Spinner", mod })
+type Args = { variant: SpinnerVariantName; speed: number; size: number }
 
 export default {
   title: "UI/Spinner",
   id: "components-spinner",
-  component: story.meta.component,
+  component: Spinner,
   tags: ["autodocs"],
+  args: { variant: "today", speed: 1, size: 16 },
+  argTypes: {
+    variant: { control: "select", options: ["today", ...Object.keys(spinnerVariants)] },
+    speed: { control: { type: "range", min: 0.25, max: 2, step: 0.05 } },
+    size: { control: { type: "range", min: 12, max: 48, step: 1 } },
+  },
+  render: (args: Args) => (
+    <Spinner
+      variant={args.variant}
+      style={{ width: `${args.size}px`, height: `${args.size}px`, "--spinner-time": String(1 / args.speed) }}
+    />
+  ),
   parameters: {
     docs: {
       description: {
@@ -40,14 +46,16 @@ export default {
   },
 }
 
-export const Basic = story.Basic
+export const Today = { args: { variant: "today" } }
 
-export const Sizes = {
-  render: () => (
-    <div style={{ display: "flex", gap: "16px", "align-items": "center" }}>
-      <mod.Spinner style={{ width: "12px", height: "12px" }} />
-      <mod.Spinner style={{ width: "20px", height: "20px" }} />
-      <mod.Spinner style={{ width: "28px", height: "28px" }} />
-    </div>
-  ),
-}
+export const SoftRadar = { args: { variant: "radar" } }
+
+export const OrbRadar = { args: { variant: "orbRadar" } }
+
+export const CentreRipple = { args: { variant: "ripple" } }
+
+export const BorderSnake = { args: { variant: "snake" } }
+
+export const SpiralFill = { args: { variant: "spiral" } }
+
+export const BreathingGrid = { args: { variant: "breathe" } }
diff --git a/packages/ui/src/components/spinner.tsx b/packages/ui/src/components/spinner.tsx
index 7c79575a5a9..07e04cc1de3 100644
--- a/packages/ui/src/components/spinner.tsx
+++ b/packages/ui/src/components/spinner.tsx
@@ -1,19 +1,100 @@
-import { type ComponentProps } from "solid-js"
+import { createSignal, For, Show, splitProps, type ComponentProps } from "solid-js"
+import { syncSpinPhase } from "../hooks/spin-phase"
+import { motionTuning } from "../motion-tuning"
+import { spinnerDots, spinnerKeyframes, spinnerVariants, type SpinnerVariant } from "./spinner-variants"
+
+export type SpinnerVariantName = "today" | keyof typeof spinnerVariants
+
+// Experiment: dot-matrix variations to try in place of today's spinner, everywhere it shows (tabs, loaders, the
+// update button), before one ships.
+const choice = motionTuning.choice("spinner.variant", {
+  label: "Activity spinner",
+  group: "Experiments",
+  value: "today",
+  // SAFETY: built from spinnerVariants' own keys, plus "today".
+  labels: Object.fromEntries([
+    ["today", "Today"],
+    ...Object.entries(spinnerVariants).map(([name, variant]) => [name, variant.label]),
+  ]) as Record<SpinnerVariantName, string>,
+})
+
+const [chosen, setChosen] = createSignal(choice())
+
+motionTuning.subscribe(() => setChosen(choice()))
+
+// Each variation's keyframes are added to the document once, the first time one renders.
+const added = new Set<string>()
+
+export function Spinner(props: ComponentProps<"svg"> & { "data-component"?: string; variant?: SpinnerVariantName }) {
+  const [local, rest] = splitProps(props, ["variant", "class", "classList", "data-component"])
+  const name = () => local.variant ?? chosen()
+  // SAFETY: "today" is the only name that isn't a key of spinnerVariants, and it maps to undefined.
+  const variant = (): SpinnerVariant | undefined => spinnerVariants[name() as keyof typeof spinnerVariants]
+  const classList = () => ({ ...local.classList, [local.class ?? ""]: !!local.class })
 
-export function Spinner(props: ComponentProps<"svg"> & { "data-component"?: string }) {
   return (
-    <svg
-      {...props}
-      viewBox="0 0 16 16"
-      data-component={props["data-component"] ?? "spinner"}
-      data-slot="spinner-grid"
-      classList={{
-        ...props.classList,
-        [props.class ?? ""]: !!props.class,
-      }}
-      fill="currentColor"
+    // Keyed, so switching variations builds a fresh SVG: its dots, keyframes and phase pin all come from the new one.
+    <Show
+      when={variant()}
+      keyed
+      fallback={
+        <svg
+          {...rest}
+          viewBox="0 0 16 16"
+          data-component={local["data-component"] ?? "spinner"}
+          data-slot="spinner-grid"
+          classList={classList()}
+          fill="currentColor"
+        >
+          <rect data-reduced-motion x={7} y={7} width={2} height={2} />
+        </svg>
+      }
     >
-      <rect data-reduced-motion x={7} y={7} width={2} height={2} />
-    </svg>
+      {(current) => {
+        const keyframes = `spinner-${name()}`
+
+        if (!added.has(keyframes)) {
+          added.add(keyframes)
+          const style = document.createElement("style")
+          style.textContent = spinnerKeyframes(keyframes, current)
+          document.head.append(style)
+        }
+
+        return (
+          <svg
+            {...rest}
+            ref={syncSpinPhase}
+            viewBox="0 0 16 16"
+            data-component={local["data-component"] ?? "spinner"}
+            data-slot="spinner-dots"
+            data-variant={name()}
+            classList={classList()}
+            fill="currentColor"
+          >
+            <For each={spinnerDots(current)}>
+              {(dot) => {
+                const loop = current.loop * dot.scale
+
+                return (
+                  <rect
+                    x={dot.x}
+                    y={dot.y}
+                    width={dot.size}
+                    height={dot.size}
+                    rx={dot.size * 0.24}
+                    style={{
+                      "--still": dot.hold === "lit" ? 1 : dot.hold === "rest" ? current.dim : dot.still,
+                      animation: dot.hold
+                        ? undefined
+                        : `${keyframes} calc(${loop}s * var(--spinner-time, 1)) linear calc(${-loop * (1 - dot.at)}s * var(--spinner-time, 1)) infinite`,
+                    }}
+                  />
+                )
+              }}
+            </For>
+          </svg>
+        )
+      }}
+    </Show>
   )
 }
diff --git a/packages/ui/src/hooks/spin-phase.ts b/packages/ui/src/hooks/spin-phase.ts
index ee0132e2fb4..89623d4e273 100644
--- a/packages/ui/src/hooks/spin-phase.ts
+++ b/packages/ui/src/hooks/spin-phase.ts
@@ -2,17 +2,43 @@ import { onCleanup } from "solid-js"
 
 // ResizeObserver delivers after style and layout but before paint, so a spinner that mounts or leaves `display: none`
 // (which restarts its CSS animation) paints its first frame already in phase.
-const observer =
+const resize =
   typeof ResizeObserver === "undefined"
     ? undefined
-    : new ResizeObserver((entries) => entries.forEach((entry) => pinSpinPhase(entry.target)))
+    : new ResizeObserver((entries) => entries.forEach((entry) => pinVisible(entry.target)))
 
-/** Use as a `ref` on a looping indicator so every instance on screen shares one phase. */
+// Spinners scrolled or clipped out of view, under a `display: none` or `content-visibility: hidden` ancestor, or sized
+// to nothing get `data-offscreen`, which their CSS uses to pause. Coming back, they resume and re-pin to the shared
+// phase. `visibility: hidden` and `opacity: 0` still count as visible.
+const visibility =
+  typeof IntersectionObserver === "undefined"
+    ? undefined
+    : new IntersectionObserver((entries) =>
+        entries.forEach((entry) => {
+          entry.target.toggleAttribute("data-offscreen", !entry.isIntersecting)
+          pinVisible(entry.target)
+        }),
+      )
+
+/** Use as a `ref` on a looping indicator so every instance on screen shares one phase and pauses while hidden. */
 export function syncSpinPhase(el: Element) {
-  observer?.observe(el)
+  resize?.observe(el)
+  visibility?.observe(el)
   // Turning reduced motion back off restarts the animation without resizing anything.
-  el.addEventListener("animationstart", () => pinSpinPhase(el))
-  onCleanup(() => observer?.unobserve(el))
+  el.addEventListener("animationstart", () => pinVisible(el))
+  onCleanup(() => {
+    resize?.unobserve(el)
+    visibility?.unobserve(el)
+  })
+}
+
+// Setting the start time of a paused CSS animation resumes it and makes it ignore `animation-play-state` from then on,
+// so a paused spinner is left alone until it is visible. `getAnimations` flushes style, so a spinner that has just
+// lost `data-offscreen` is running again by the time it is pinned.
+function pinVisible(el: Element) {
+  if (el.hasAttribute("data-offscreen")) return
+
+  pinSpinPhase(el)
 }
 
 // Starting every infinite loop at the document timeline's origin puts all instances of one animation in phase.