Add Stationery and Stationery Dark themes with notebook chrome.

Manila folders, ruled chat, post-it nav, and folder tabs; dark variant uses Catppuccin Mocha colors with muted stickies and soft glows.

src/app/components/message/StationeryMedia.tsx

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+import React, {
+  ComponentProps,
+  CSSProperties,
+  MouseEventHandler,
+  ReactNode,
+  useCallback,
+  useMemo,
+  useRef,
+} from 'react';
+import { Attachment } from './attachment';
+import { isStationeryTheme, useTheme } from '../../hooks/useTheme';
+
+type Corner = 'tl' | 'tr' | 'bl' | 'br';
+
+type StationeryMediaProps = ComponentProps<typeof Attachment> & {
+  children: ReactNode;
+  /** Stable id (e.g. mxc URL) so tilt/tape don't reshuffle on timeline re-renders */
+  tiltSeed?: string;
+  /** Invisible bottom spacer (px) so following text stays on the ruled grid */
+  gridPad?: number;
+};
+
+const CORNERS: { id: Corner; x: 0 | 1; y: 0 | 1 }[] = [
+  { id: 'tl', x: 0, y: 0 },
+  { id: 'tr', x: 1, y: 0 },
+  { id: 'bl', x: 0, y: 1 },
+  { id: 'br', x: 1, y: 1 },
+];
+
+const MEDIA_ROTS = [-0.9, 0.7, -0.5, 1.0, -1.1, 0.8, -0.4, 0.9] as const;
+
+export function hashStationerySeed(seed: string): number {
+  let h = 2166136261;
+  for (let i = 0; i < seed.length; i += 1) {
+    h ^= seed.charCodeAt(i);
+    h = Math.imul(h, 16777619);
+  }
+  return h >>> 0;
+}
+
+export function stationeryMediaRot(seed: string): string {
+  return `${MEDIA_ROTS[hashStationerySeed(seed) % MEDIA_ROTS.length]}deg`;
+}
+
+const clamp = (n: number, min: number, max: number) => Math.max(min, Math.min(max, n));
+
+/**
+ * Fold sits halfway between corner and cursor; flap hinges on that fold.
+ * `keep` = remaining photo; `flap` = lifted triangle.
+ */
+function cornerPeelPaths(
+  id: Corner,
+  w: number,
+  h: number,
+  cx: number,
+  cy: number,
+  ux: number,
+  uy: number,
+  size: number
+): {
+  keep: string;
+  flap: string;
+  origin: string;
+  axisX: number;
+  axisY: number;
+  hingeSign: number;
+} {
+  const eps = 0.0001;
+  // Fold line through the midpoint on corner→cursor, ⊥ to that ray
+  const px = cx + ux * size;
+  const py = cy + uy * size;
+
+  let ax = 0;
+  let ay = 0;
+  let bx = 0;
+  let by = 0;
+
+  if (id === 'tr') {
+    ax = clamp(Math.abs(ux) > eps ? px + (py * uy) / ux : px, 0, w);
+    ay = 0;
+    bx = w;
+    by = clamp(Math.abs(uy) > eps ? py - ((w - px) * ux) / uy : py, 0, h);
+  } else if (id === 'tl') {
+    ax = clamp(Math.abs(ux) > eps ? px + (py * uy) / ux : px, 0, w);
+    ay = 0;
+    bx = 0;
+    by = clamp(Math.abs(uy) > eps ? py - ((0 - px) * ux) / uy : py, 0, h);
+  } else if (id === 'br') {
+    ax = clamp(Math.abs(ux) > eps ? px + ((py - h) * uy) / ux : px, 0, w);
+    ay = h;
+    bx = w;
+    by = clamp(Math.abs(uy) > eps ? py - ((w - px) * ux) / uy : py, 0, h);
+  } else {
+    ax = clamp(Math.abs(ux) > eps ? px + ((py - h) * uy) / ux : px, 0, w);
+    ay = h;
+    bx = 0;
+    by = clamp(Math.abs(uy) > eps ? py - ((0 - px) * ux) / uy : py, 0, h);
+  }
+
+  let keep: string;
+  if (id === 'tr') {
+    keep = `polygon(0 0, ${ax}px 0, ${w}px ${by}px, ${w}px ${h}px, 0 ${h}px)`;
+  } else if (id === 'tl') {
+    keep = `polygon(${ax}px 0, ${w}px 0, ${w}px ${h}px, 0 ${h}px, 0 ${by}px)`;
+  } else if (id === 'br') {
+    keep = `polygon(0 0, ${w}px 0, ${w}px ${by}px, ${ax}px ${h}px, 0 ${h}px)`;
+  } else {
+    keep = `polygon(0 0, ${w}px 0, ${w}px ${h}px, ${ax}px ${h}px, 0 ${by}px)`;
+  }
+
+  const flap = `polygon(${cx}px ${cy}px, ${ax}px ${ay}px, ${bx}px ${by}px)`;
+
+  // Hinge on the fold (midpoint), axis along the fold edge
+  const midX = (ax + bx) / 2;
+  const midY = (ay + by) / 2;
+  const fdx = bx - ax;
+  const fdy = by - ay;
+  const flen = Math.hypot(fdx, fdy) || 1;
+  const axisX = fdx / flen;
+  const axisY = fdy / flen;
+  // Sign so the corner swings up over the fold (right-hand rule)
+  const cross = fdx * (cy - midY) - fdy * (cx - midX);
+  const hingeSign = cross >= 0 ? 1 : -1;
+
+  return {
+    keep,
+    flap,
+    origin: `${midX}px ${midY}px`,
+    axisX,
+    axisY,
+    hingeSign,
+  };
+}
+
+/**
+ * Stationery-theme image chrome: clear corner tape + a mouse-driven peel
+ * that shows a duplicated slice of the photo lifting toward the cursor.
+ */
+export function StationeryMedia({
+  children,
+  tiltSeed = 'stationery',
+  gridPad = 0,
+  style,
+  ...attachmentProps
+}: StationeryMediaProps) {
+  const theme = useTheme();
+  const isStationery = isStationeryTheme(theme);
+  const peelRef = useRef<HTMLSpanElement>(null);
+
+  const tiltStyle = useMemo((): CSSProperties => {
+    return {
+      ...(style as CSSProperties | undefined),
+      // Margin sits outside the paper chrome — snaps the grid without a white bar
+      ...(isStationery && gridPad > 0 ? { marginBottom: `${gridPad}px` } : null),
+      ['--media-rot' as string]: stationeryMediaRot(tiltSeed),
+    };
+  }, [tiltSeed, style, isStationery, gridPad]);
+
+  const tapeAlt = useMemo(() => hashStationerySeed(tiltSeed) % 2 === 1, [tiltSeed]);
+  // Default tape covers TL; alt covers TR — peel only the free top corner
+  const peelCorner = useMemo(
+    () => (tapeAlt ? CORNERS.find((c) => c.id === 'tl')! : CORNERS.find((c) => c.id === 'tr')!),
+    [tapeAlt]
+  );
+
+  const clearPeel = useCallback((host: HTMLElement) => {
+    const peel = peelRef.current;
+    const target = host.querySelector('[data-paarrot-media-height]') as HTMLElement | null;
+    if (peel) {
+      // Hide flap first (no opacity tween) so restoring the photo can't double-draw
+      peel.style.transition = 'none';
+      peel.style.opacity = '0';
+      peel.style.setProperty('--peel-hinge', '0deg');
+      peel.style.clipPath = '';
+    }
+    if (target) target.style.clipPath = '';
+  }, []);
+
+  const syncPeel = useCallback(
+    (host: HTMLElement, clientX: number, clientY: number) => {
+      const peel = peelRef.current;
+      if (!peel) return;
+
+      const rect = host.getBoundingClientRect();
+      const x = clientX - rect.left;
+      const y = clientY - rect.top;
+      const w = rect.width;
+      const h = rect.height;
+
+      const best = peelCorner;
+      const cx = best.x * w;
+      const cy = best.y * h;
+      const dist = Math.hypot(cx - x, cy - y);
+      const maxReach = Math.min(w, h) * 0.55;
+
+      // Fold halfway between corner and cursor; fade when leaving the corner zone
+      let size = 0;
+      let amount = 0;
+      if (dist > 8 && dist <= maxReach) {
+        size = dist * 0.5;
+        amount = Math.min(1, size / (Math.min(w, h) * 0.22));
+      } else if (dist > maxReach && dist < maxReach * 1.35) {
+        const fade = 1 - (dist - maxReach) / (maxReach * 0.35);
+        size = maxReach * 0.5 * Math.max(0, fade);
+        amount = Math.max(0, fade);
+      }
+
+      const img = host.querySelector('img');
+      const url = img?.currentSrc || img?.src || '';
+
+      // Unit vector from corner → cursor (triangle aims this way)
+      let ux = x - cx;
+      let uy = y - cy;
+      if (best.id === 'tr') {
+        ux = Math.min(-0.05, ux);
+        uy = Math.max(0.05, uy);
+      } else {
+        ux = Math.max(0.05, ux);
+        uy = Math.max(0.05, uy);
+      }
+      const len = Math.hypot(ux, uy) || 1;
+      ux /= len;
+      uy /= len;
+
+      peel.dataset.corner = best.id;
+      if (url) {
+        peel.style.setProperty('--peel-img', `url(${JSON.stringify(url)})`);
+      }
+
+      const target = host.querySelector('[data-paarrot-media-height]') as HTMLElement | null;
+      if (target && amount > 0.06 && size > 6) {
+        const { keep, flap, origin, axisX, axisY, hingeSign } = cornerPeelPaths(
+          best.id,
+          w,
+          h,
+          cx,
+          cy,
+          ux,
+          uy,
+          size
+        );
+        target.style.clipPath = keep;
+        peel.style.clipPath = flap;
+        peel.style.transformOrigin = origin;
+        peel.style.setProperty('--peel-axis-x', String(axisX));
+        peel.style.setProperty('--peel-axis-y', String(axisY));
+        peel.style.setProperty('--peel-hinge', `${hingeSign * amount * 52}deg`);
+        peel.style.setProperty('--peel-tip-x', `${cx}px`);
+        peel.style.setProperty('--peel-tip-y', `${cy}px`);
+        peel.style.setProperty('--peel-grad-r', `${Math.max(size * 1.15, 12)}px`);
+        peel.style.opacity = '1';
+      } else {
+        clearPeel(host);
+      }
+    },
+    [peelCorner, clearPeel]
+  );
+
+  const handleMove: MouseEventHandler<HTMLElement> = (evt) => {
+    syncPeel(evt.currentTarget, evt.clientX, evt.clientY);
+  };
+
+  const handleEnter: MouseEventHandler<HTMLElement> = (evt) => {
+    syncPeel(evt.currentTarget, evt.clientX, evt.clientY);
+  };
+
+  const handleLeave: MouseEventHandler<HTMLElement> = (evt) => {
+    clearPeel(evt.currentTarget);
+  };
+
+  if (!isStationery) {
+    return (
+      <Attachment style={style} {...attachmentProps}>
+        {children}
+      </Attachment>
+    );
+  }
+
+  return (
+    <Attachment
+      {...attachmentProps}
+      style={tiltStyle}
+      data-stationery-media=""
+      data-tape-alt={tapeAlt ? '' : undefined}
+      onMouseEnter={handleEnter}
+      onMouseMove={handleMove}
+      onMouseLeave={handleLeave}
+    >
+      <span ref={peelRef} data-stationery-peel="" aria-hidden="true" />
+      {children}
+    </Attachment>
+  );
+}