chore: import upstream snapshot with attribution

apps/sim/components/ui/thinking-loader.tsx

@@ -0,0 +1,448 @@
+'use client'
+
+import { type CSSProperties, type ReactNode, useEffect, useId, useState } from 'react'
+import { cn } from '@sim/emcn'
+import styles from '@/components/ui/thinking-loader.module.css'
+
+const VARIANTS = [
+  'metaballs',
+  'relay',
+  'corners',
+  'burst',
+  'compass',
+  'squeeze',
+  'thinking',
+  'orb',
+] as const
+
+export type ThinkingLoaderVariant = (typeof VARIANTS)[number]
+
+/**
+ * Shapes used in the random morph cycle. `orb` (the solid terminal circle) is
+ * excluded — it is only reachable by pinning `variant='orb'` or via `settle`,
+ * so the cycle never lands on it mid-stream.
+ */
+const CYCLE_VARIANTS = VARIANTS.filter((v) => v !== 'orb')
+
+/**
+ * Deterministic integer hash — turns a step index into a spread-out pseudo-
+ * random number. Used to pick both the shape and its hold time per step, so the
+ * order and pacing look unpredictable (any shape can follow any other, some
+ * linger, some pass quickly) while staying a pure function of the clock — every
+ * loader instance lands on the same shape at the same time.
+ */
+function hashStep(n: number): number {
+  let x = n | 0
+  x = Math.imul((x >>> 16) ^ x, 0x45d9f3b)
+  x = Math.imul((x >>> 16) ^ x, 0x45d9f3b)
+  return ((x >>> 16) ^ x) >>> 0
+}
+
+/**
+ * Common multiple of every shape animation period (800/1000/1200/2000ms,
+ * alternates doubled) — the wall-clock modulus for the shared negative
+ * animation-delay that phase-locks instances mounted at different times.
+ */
+const SYNC_PERIOD_MS = 12_000
+
+/**
+ * A super-cycle of steps, each holding a pseudo-random shape for a pseudo-random
+ * duration (≈1.1–2.6s), so the morph pacing feels natural — some shapes linger,
+ * some pass quickly — instead of a metronome. Deterministic, so instances stay
+ * in lockstep; long enough not to read as a loop.
+ */
+const CYCLE_STEPS = 16
+const STEP_MIN_MS = 1100
+const STEP_RANGE_MS = 1500
+const STEP_DURATIONS = Array.from(
+  { length: CYCLE_STEPS },
+  (_, i) => STEP_MIN_MS + (hashStep(i + 1000) % STEP_RANGE_MS)
+)
+const SUPER_PERIOD_MS = STEP_DURATIONS.reduce((sum, d) => sum + d, 0)
+
+/** The shape for a given step — pseudo-random, never an immediate repeat. */
+function variantForStep(i: number): ThinkingLoaderVariant {
+  const idx = hashStep(i) % CYCLE_VARIANTS.length
+  const prevIdx = hashStep((i - 1 + CYCLE_STEPS) % CYCLE_STEPS) % CYCLE_VARIANTS.length
+  return CYCLE_VARIANTS[idx === prevIdx ? (idx + 1) % CYCLE_VARIANTS.length : idx]
+}
+
+/**
+ * The shape the shared timeline is on right now, and how long until the next.
+ * Walks the super-cycle's varied step durations — a pure function of the wall
+ * clock, so instances stay in lockstep.
+ */
+function variantAtNow(): { variant: ThinkingLoaderVariant; msUntilNext: number } {
+  let t = Date.now() % SUPER_PERIOD_MS
+  for (let i = 0; i < CYCLE_STEPS; i++) {
+    if (t < STEP_DURATIONS[i]) {
+      return { variant: variantForStep(i), msUntilNext: STEP_DURATIONS[i] - t }
+    }
+    t -= STEP_DURATIONS[i]
+  }
+  return { variant: variantForStep(0), msUntilNext: STEP_DURATIONS[0] }
+}
+
+/**
+ * Ink shapes per variant, authored in the shared 100x100 viewBox.
+ * Geometry mirrors the intrinsic CSS loaders these were adapted from,
+ * contain-fit to the canvas. Animations live in the CSS module.
+ */
+const VARIANT_SHAPES: Record<ThinkingLoaderVariant, ReactNode> = {
+  metaballs: (
+    <>
+      <circle className={styles.metaballsA} cx='22' cy='50' r='16' />
+      <circle className={styles.metaballsB} cx='78' cy='50' r='16' />
+    </>
+  ),
+  relay: (
+    <>
+      <rect x='13' y='28' width='16' height='44' />
+      <rect x='71' y='28' width='16' height='44' />
+      <circle className={styles.relayBall} cx='21' cy='50' r='14' />
+    </>
+  ),
+  corners: (
+    <>
+      <rect x='27' y='27' width='46' height='46' />
+      <circle className={styles.cornersA} cx='27' cy='27' r='14' />
+      <circle className={styles.cornersB} cx='73' cy='27' r='14' />
+      <circle className={styles.cornersC} cx='73' cy='73' r='14' />
+      <circle className={styles.cornersD} cx='27' cy='73' r='14' />
+    </>
+  ),
+  // burst (Thinking) — four dots fling out of a center cross and are swallowed
+  // at the window edge, then fire again: the Core churning.
+  burst: (
+    <>
+      <rect x='12.5' y='43.75' width='75' height='12.5' />
+      <rect x='43.75' y='12.5' width='12.5' height='75' />
+      <circle cx='50' cy='50' r='12.5' />
+      <circle className={styles.burstUp} cx='50' cy='50' r='12.5' />
+      <circle className={styles.burstDown} cx='50' cy='50' r='12.5' />
+      <circle className={styles.burstLeft} cx='50' cy='50' r='12.5' />
+      <circle className={styles.burstRight} cx='50' cy='50' r='12.5' />
+    </>
+  ),
+  compass: (
+    <>
+      <circle cx='50' cy='23' r='14' />
+      <circle cx='23' cy='50' r='14' />
+      <circle cx='77' cy='50' r='14' />
+      <circle cx='50' cy='77' r='14' />
+      <circle className={styles.compassMover} cx='50' cy='23' r='14' />
+    </>
+  ),
+  squeeze: (
+    <>
+      {/* Arcs are stroked, not filled — they inherit the group's gradient stroke
+          (so the O is shaded identically to every other shape); the group pins
+          stroke-width to 0, so each arc re-asserts its own 12.5. */}
+      <path d='M 21.36 37.5 A 31.25 31.25 0 0 1 78.64 37.5' fill='none' strokeWidth='12.5' />
+      <path d='M 21.36 62.5 A 31.25 31.25 0 0 0 78.64 62.5' fill='none' strokeWidth='12.5' />
+      <rect className={styles.squeezeBarL} x='15' y='37.5' width='12.5' height='25' />
+      <rect className={styles.squeezeBarR} x='72.5' y='37.5' width='12.5' height='25' />
+    </>
+  ),
+  // thinking — a core with small blobs drifting out and back on offset timings:
+  // a restless thought-cloud that never quite resolves. The Core deliberating.
+  thinking: (
+    <>
+      <circle cx='50' cy='50' r='15' />
+      <circle className={styles.thinkA} cx='50' cy='50' r='12' />
+      <circle className={styles.thinkB} cx='50' cy='50' r='12' />
+      <circle className={styles.thinkC} cx='50' cy='50' r='11' />
+    </>
+  ),
+  // orb — a single solid disc that nearly fills the frame. Not part of the
+  // random cycle; the loader settles here so it can hand off to a real circular
+  // button (e.g. a send button) without a visible shape pop.
+  orb: <circle cx='50' cy='50' r='42' />,
+}
+
+/**
+ * World-aligned status phrase per shape (used when `phase` is set). Each phrase
+ * names what the shape represents in the Sim world, so the words on screen always
+ * match the loader. Keys are the shape names; the comment is the world concept.
+ */
+const VARIANT_PHRASE: Record<ThinkingLoaderVariant, string> = {
+  corners: 'Orchestrating…', // Mothership — the Core directing the work
+  squeeze: 'Working…', // Pod — one agent on a task
+  compass: 'In formation…', // Formation — many Pods in parallel
+  metaballs: 'Dispatching…', // Dispatch — sending work out
+  relay: 'Returning…', // Return — work coming back, consolidated
+  burst: 'Thinking…', // Thinking — the Core deliberating
+  thinking: 'Standing by…', // Waiting · Sentinel — holding for a condition
+  orb: 'Ready', // Orb — settled, ready to act
+}
+
+export interface ThinkingLoaderProps {
+  /** Pin one pattern. When omitted, the loader morphs between all patterns at random. */
+  variant?: ThinkingLoaderVariant
+  /**
+   * When cycling, open on this pattern (held one beat) before joining the
+   * shared morph timeline. Use `'corners'` (the Mothership shape) to always
+   * begin on the Core. Ignored when `variant` pins a single pattern.
+   */
+  startVariant?: ThinkingLoaderVariant
+  /**
+   * Stop cycling and morph to the solid `orb` disc — the loader's terminal
+   * resting shape. The goo filter melts the current shape into the orb (no hard
+   * swap), so it can hand off to a real circular element underneath it. Ignored
+   * when `variant` pins a single pattern.
+   */
+  settle?: boolean
+  /** Rendered square size in px. Defaults to 20. */
+  size?: number
+  /** Optional status text (e.g. "Thinking…") rendered beside the goo with a shimmer sweep. */
+  label?: string
+  /**
+   * Show a world-aligned status phrase that matches the current shape — e.g.
+   * "Dispatching…" under the Dispatch shape — updating as the loader morphs.
+   * Overrides `label`.
+   */
+  phase?: boolean
+  /**
+   * Phrase/label font size as a fraction of `size`. Defaults to `0.7`. Lower it
+   * when the loader is shown scaled up (e.g. a zoomed hero shot) so the phrase
+   * doesn't read oversized next to the glyph.
+   */
+  labelRatio?: number
+  /**
+   * Paint the label with the sweeping Claude-style shimmer (default). Set
+   * `false` for a static label in solid `--text-body` ink — no gradient, no
+   * sweep — while the phrase crossfade still applies.
+   */
+  shimmer?: boolean
+  /** Layout-only classes (margins, alignment). The loader owns its chrome. */
+  className?: string
+  /**
+   * Escape hatch for the ink material: merged onto the SVG, so a caller can
+   * override the gradient/glow CSS vars (`--tl-grad-inner`, `--tl-grad-outer`,
+   * `--tl-glow`) to match a surface it hands off to. Inline, so it beats the
+   * module defaults. Use sparingly — the loader owns its look by default.
+   */
+  style?: CSSProperties
+}
+
+/**
+ * Gooey mono thinking indicator shown wherever chat is working.
+ * Ink is near-black on light surfaces and off-white on dark surfaces.
+ *
+ * The goo filter operates on the alpha channel of transparent SVG shapes,
+ * so the loader needs no backdrop and composites on any background. All
+ * patterns share one filtered group, so the default cycling mode melts one
+ * pattern into the next instead of hard-swapping.
+ *
+ * @example
+ * ```tsx
+ * <ThinkingLoader label='Thinking…' />
+ * ```
+ */
+export function ThinkingLoader({
+  variant,
+  startVariant,
+  settle = false,
+  size = 20,
+  label,
+  phase,
+  labelRatio = 0.7,
+  shimmer = true,
+  className,
+  style,
+}: ThinkingLoaderProps) {
+  // useId emits colons, which break url(#...) filter references — strip them.
+  const id = useId().replace(/[^a-zA-Z0-9-]/g, '')
+  const filterId = `tl-goo-${id}`
+  const clipId = `tl-clip-${id}`
+  const windowClipId = `tl-window-${id}`
+  const gradientId = `tl-grad-${id}`
+  const [cycleVariant, setCycleVariant] = useState<ThinkingLoaderVariant>(
+    startVariant ?? 'metaballs'
+  )
+  const cycling = variant === undefined
+
+  useEffect(() => {
+    if (!cycling) return
+    // Settle: stop the cycle and melt to the terminal orb (goo handles the morph).
+    if (settle) {
+      setCycleVariant('orb')
+      return
+    }
+    if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) return
+
+    // When a startVariant is given, hold it for one min-step so the cycle always
+    // opens on that shape, then join the shared wall-clock morph timeline.
+    let opened = startVariant === undefined
+    let timeout: ReturnType<typeof setTimeout>
+    const tick = () => {
+      if (!opened) {
+        opened = true
+        setCycleVariant(startVariant as ThinkingLoaderVariant)
+        timeout = setTimeout(tick, STEP_MIN_MS)
+        return
+      }
+      const { variant: next, msUntilNext } = variantAtNow()
+      setCycleVariant(next)
+      timeout = setTimeout(tick, msUntilNext)
+    }
+    tick()
+    return () => clearTimeout(timeout)
+  }, [cycling, startVariant, settle])
+
+  // Phase-lock the CSS animations to the wall clock (set after mount so
+  // server and client markup agree). All instances share the same negative
+  // delay modulus, so their keyframes line up regardless of mount time.
+  const [syncDelay, setSyncDelay] = useState<string | undefined>(undefined)
+  useEffect(() => {
+    setSyncDelay(`-${Date.now() % SYNC_PERIOD_MS}ms`)
+  }, [])
+
+  const shown = variant ?? cycleVariant
+  // `phase` shows the world phrase for the shape on screen; otherwise the
+  // caller's static label (if any). Cycling, it updates as the shape morphs.
+  const displayLabel = phase ? VARIANT_PHRASE[shown] : label
+
+  // Crossfade the phrase when it changes: the outgoing phrase rises and fades
+  // out while the incoming one rises and fades in, so they rotate smoothly
+  // instead of snapping. The shimmer keeps running on the text underneath.
+  const [shownLabel, setShownLabel] = useState(displayLabel)
+  const [exitingLabel, setExitingLabel] = useState<string | undefined>(undefined)
+  useEffect(() => {
+    if (displayLabel === shownLabel) return
+    setExitingLabel(shownLabel)
+    setShownLabel(displayLabel)
+  }, [displayLabel, shownLabel])
+  useEffect(() => {
+    if (!exitingLabel) return
+    const timeout = setTimeout(() => setExitingLabel(undefined), 420)
+    return () => clearTimeout(timeout)
+  }, [exitingLabel])
+
+  const stages = cycling ? VARIANTS : [shown]
+
+  const loader = (
+    <svg
+      role={displayLabel ? undefined : 'status'}
+      aria-label={displayLabel ? undefined : 'Thinking'}
+      aria-hidden={displayLabel ? true : undefined}
+      viewBox='0 0 100 100'
+      width={size}
+      height={size}
+      className={cn(styles.frame, !displayLabel && className)}
+      style={{
+        ...(syncDelay ? ({ '--tl-sync': syncDelay } as CSSProperties) : {}),
+        ...style,
+      }}
+    >
+      <defs>
+        {/* sRGB so the radial gradient fill keeps its authored midtones
+            through the blur (linearRGB would wash the gradient out). The goo
+            crush runs first; the inner glow then rides the merged silhouette's
+            edge — a soft white inset, per the Figma loader spec. */}
+        <filter
+          id={filterId}
+          x='-30%'
+          y='-30%'
+          width='160%'
+          height='160%'
+          colorInterpolationFilters='sRGB'
+        >
+          <feGaussianBlur in='SourceGraphic' stdDeviation='5' result='blur' />
+          <feColorMatrix
+            in='blur'
+            values='1 0 0 0 0  0 1 0 0 0  0 0 1 0 0  0 0 0 19 -9'
+            result='goo'
+          />
+          {/* Inner shadow from the goo silhouette's alpha (Figma technique:
+              blur the alpha, subtract it from itself to leave an inner ring,
+              tint white). stdDeviation 4.86 = the spec's 3.5 scaled 72→100. */}
+          <feColorMatrix
+            in='goo'
+            type='matrix'
+            values='0 0 0 0 0  0 0 0 0 0  0 0 0 0 0  0 0 0 127 0'
+            result='gooAlpha'
+          />
+          <feGaussianBlur in='gooAlpha' stdDeviation='4.86' result='innerBlur' />
+          <feComposite
+            in='innerBlur'
+            in2='gooAlpha'
+            operator='arithmetic'
+            k2='-1'
+            k3='1'
+            result='innerMask'
+          />
+          {/* Glow color + per-theme opacity ride a CSS var (light 0.6 / dark
+              0.9) so one filter serves both themes. */}
+          <feFlood className={styles.glow} result='glowColor' />
+          <feComposite in='glowColor' in2='innerMask' operator='in' result='glow' />
+          <feMerge>
+            <feMergeNode in='goo' />
+            <feMergeNode in='glow' />
+          </feMerge>
+        </filter>
+        {/* Radial gradient (center → edge), theme stops via CSS vars. Matches
+            the Figma loader: light #4F4F4F→#6F6F6F, dark #A7A7A7→#D6D6D6.
+            objectBoundingBox (default units) so EACH blob is shaded on its own
+            box — Figma fits the gradient per shape, so small/offset dots read
+            glossy (center dark, edge light) instead of flat. */}
+        <radialGradient id={gradientId} cx='0.5' cy='0.5' r='0.5'>
+          <stop className={styles.gradInner} />
+          <stop offset='1' className={styles.gradOuter} />
+        </radialGradient>
+        {/* Shapes clip BEFORE the goo filter, so anything exiting the frame
+            melts into the edge instead of getting a hard post-filter cut. */}
+        <clipPath id={clipId}>
+          <rect width='100' height='100' />
+        </clipPath>
+        {/* The original burst loader hid its flying dots under a 10px border,
+            swallowing them at the inner window — this clip reproduces it. */}
+        <clipPath id={windowClipId}>
+          <rect x='12.5' y='12.5' width='75' height='75' />
+        </clipPath>
+      </defs>
+      <g
+        filter={`url(#${filterId})`}
+        fill={`url(#${gradientId})`}
+        stroke={`url(#${gradientId})`}
+        strokeWidth={0}
+      >
+        {stages.map((v) => (
+          <g
+            key={v}
+            clipPath={`url(#${v === 'burst' ? windowClipId : clipId})`}
+            className={cn(styles.stage, v === shown && styles.stageActive)}
+          >
+            {VARIANT_SHAPES[v]}
+          </g>
+        ))}
+      </g>
+    </svg>
+  )
+
+  if (!displayLabel) return loader
+
+  return (
+    <output
+      className={cn(styles.labelRow, className)}
+      style={
+        {
+          '--tl-label-size': `${size * labelRatio}px`,
+          '--tl-label-gap': `${size * 0.4}px`,
+        } as CSSProperties
+      }
+    >
+      {loader}
+      <span className={styles.labelStack}>
+        {exitingLabel ? (
+          <span key={exitingLabel} className={cn(styles.labelLayer, styles.labelOut)}>
+            <span className={shimmer ? styles.label : styles.labelStatic}>{exitingLabel}</span>
+          </span>
+        ) : null}
+        <span key={shownLabel} className={cn(styles.labelLayer, styles.labelIn)}>
+          <span className={shimmer ? styles.label : styles.labelStatic}>{shownLabel}</span>
+        </span>
+      </span>
+    </output>
+  )
+}