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← Component library

File upload

Forms

A drop zone and an upload queue — each row fills with a gradient as the bytes land, draws a check when it finishes, and slides its actions down from underneath.

DropzoneReveal drawerrole=progressbarCSS only — no dependency

Preview

  • quarterly-reconciliation.xlsx

    Uploading 38%1.8 MB of 4.8 MB

  • booking-export.csv

    Completed822 KB

1 of 2 files uploaded

Seeded rows hold the state the knob picked. Press retry or resume on one, or add a file of your own — the fill runs, the check draws itself and the actions slide down when it lands.

Controls

Notes

The row takes a name and a size, not a File. A File is the thing you happen to hold on the first attempt and never again: reload the page mid-upload, or resume one started on another device, and all you have is a filename and a byte count from the server. A component that demands a File cannot render either case.

Progress is derived from bytes rather than stored beside them. Two fields that have to agree are two fields that will eventually disagree, and the one the reader sees will be the stale one.

Every in-flight row carries a real role=progressbar labelled by its own filename. Rendering "Uploading 45%" as text is a picture of progress: nothing announces it, and nothing updates when it moves. Completed and failed rows drop the bar entirely rather than leaving a full one sitting there.

One live region for the queue, announcing how many of how many have finished. It only changes when a file completes, so that is the only time it speaks — a region that announced every tick would make the page unusable, and one per row would announce a stack of files all at once.

Complete and failed are told apart by the word and by which control sits beside them, never by colour. The tick is a span, not a disabled button: the reference put a button there purely to show it, which is a control the reader can reach and cannot use.

The progress fill is the row's background, not a bar — the card fills with colour as the bytes land, and the hairline at the bottom repeats it. Both scale rather than resize: animating width re-runs layout every frame, while scaleX with a left origin runs on the compositor. Scaling a gradient stretches it, which is the point — the ramp always spans exactly the part that has uploaded.

That fill is the AI gradient mixed 20–34% into the card rather than used neat. The tokens are bright enough to be a border; as a full background behind a filename they would bury it. Mixing toward --paper-sunken keeps the ground close to where it started, so the text contrast barely moves — and the same declaration becomes a pale wash on the light palette with no second rule.

The tile carries a tone per file kind, but each one is an existing token: the spreadsheet green is the completion green, the document blue and image purple are the two ends of the AI gradient, PDF borrows the clay accent. Six invented colours would have been six pairs to contrast-check in two themes; these already carry their own on-colour.

The check draws rather than appears — the disc pops, then the tick strokes itself on through a dash offset. It mounts only when the row completes, so the mount is the cue and there is no animation state to reset or replay by hand.

The action drawer transitions grid-template-rows from 0fr to 1fr, which is the one way to animate to a height the content decides. height: auto is not interpolable and a fixed pixel height is a guess that breaks the first time a button label wraps. The child owns the overflow: hidden, or the buttons spill out while the drawer is shut.

A closed drawer is inert. Without it the two buttons stay in the tab order and in the accessibility tree while clipped to nothing — a keyboard user tabs into a control they cannot see and a screen reader reads an action that is not offered yet.

Every action label carries the filename — "Pause quarterly-reconciliation.xlsx", not "Pause upload". The generic version is ambiguous the moment there are two rows, which is most of the time.

Drag and drop is the shortcut, not the interface. The visible control is a button that opens the file picker, so the keyboard path exists without it — and the input stays hidden behind that button rather than sitting focusable beside it, which would put two controls in the tab order for one action.

Source

Show
"use client";

import { useEffect, useId, useRef, useState } from "react";
import { cn } from "@/lib/cn";

/**
 * A file upload queue: drop or browse, then a row per file with its progress,
 * a pause, a retry and a remove.
 *
 * The row takes a NAME AND A SIZE, not a File. A File is the thing you happen
 * to hold on the first attempt and never again — reload the page mid-upload, or
 * resume one started on another device, and all you have is a filename and a
 * byte count from the server. A component that demands a File cannot render
 * either case.
 *
 * Progress is DERIVED from bytes rather than stored beside them. Two fields
 * that have to agree are two fields that will eventually disagree, and the one
 * the reader sees will be the stale one.
 *
 * Both fills scale rather than resize. Animating width re-runs layout every
 * frame; scaleX with a left origin runs on the compositor, and for a bar that
 * updates several times a second on a page that may hold twenty of them, that
 * is the difference between smooth and not.
 */
const css = `
/* The progress fill is the ROW'S BACKGROUND, not a bar — the card fills with
   colour as the bytes land, and the thin bar at the bottom repeats it. Both
   scale rather than resize: animating width re-runs layout every frame, while
   scaleX with a left origin runs on the compositor.

   Scaling a gradient stretches it, which is the point — the ramp always spans
   exactly the part that has uploaded. */
.upload-fill,
.upload-bar {
  position: absolute;
  inset: 0;
  transform-origin: left center;
  scale: var(--upload-p, 0) 1;
  transition: scale 0.3s ease-out;
  pointer-events: none;
}
/* Mixed toward the card rather than used neat. The gradient tokens are bright
   enough to be a border; as a full background behind a filename they would
   bury it, and the mix keeps the ground close to --paper-sunken so the text
   contrast barely moves. It also inverts on its own: the same declaration is a
   pale wash on the light palette. */
.upload-fill {
  background-image: linear-gradient(
    90deg,
    color-mix(in oklab, var(--ai-gradient-from) 20%, var(--paper-sunken)),
    color-mix(in oklab, var(--ai-gradient-to) 34%, var(--paper-sunken))
  );
}
.upload-bar {
  background-image: linear-gradient(90deg, var(--ai-gradient-from), var(--ai-gradient-to));
}

/* The file tile: a gradient sheet with a folded corner. */
.upload-tile {
  color: var(--tile-on);
  background-image: linear-gradient(
    155deg,
    color-mix(in oklab, var(--tile) 76%, var(--ink)),
    var(--tile)
  );
}
.upload-tile::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  inline-size: 11px;
  block-size: 11px;
  border-start-end-radius: 0.5rem;
  background: color-mix(in oklab, var(--tile) 58%, var(--paper));
  clip-path: polygon(0 0, 100% 100%, 100% 0);
}

/* The check DRAWS rather than appearing. Two animations: the disc pops, then
   the tick strokes itself on with a dash offset. It mounts only when the row
   completes, so mounting is the trigger and there is no state to reset. */
@keyframes upload-check-pop {
  from { scale: 0.5; opacity: 0; }
  to { scale: 1; opacity: 1; }
}
@keyframes upload-check-draw {
  to { stroke-dashoffset: 0; }
}
.upload-check {
  animation: upload-check-pop 0.26s cubic-bezier(0.2, 0.9, 0.3, 1.4) both;
}
.upload-check path {
  stroke-dasharray: 14;
  stroke-dashoffset: 14;
  animation: upload-check-draw 0.3s ease-out 0.12s both;
}

/* The action drawer. grid-template-rows 0fr -> 1fr is the one way to transition
   to a height the content decides; height:auto is not interpolable, and a fixed
   pixel height is a guess that breaks the moment the button text wraps. The
   child must own the overflow:hidden, or the buttons spill while it is closed. */
.upload-actions {
  display: grid;
  grid-template-rows: 0fr;
  /* The one number to tune. The label fade below trails it deliberately, so
     raising this wants its delay raised with it. */
  --upload-reveal: 0.46s;
  transition: grid-template-rows var(--upload-reveal) cubic-bezier(0.2, 0.8, 0.2, 1);
}
.upload-actions > div {
  overflow: hidden;
  min-block-size: 0;
}
.upload-actions[data-open="true"] { grid-template-rows: 1fr; }
.upload-actions > div > div {
  opacity: 0;
  transition: opacity 0.24s ease 0.14s;
}
.upload-actions[data-open="true"] > div > div { opacity: 1; }

@media (prefers-reduced-motion: reduce) {
  .upload-fill,
  .upload-bar,
  .upload-actions,
  .upload-actions > div > div { transition: none; }
  .upload-check,
  .upload-check path { animation: none; }
  .upload-check path { stroke-dashoffset: 0; }
}
`;

export type UploadStatus = "queued" | "uploading" | "paused" | "complete" | "error";

export type UploadItem = {
  id: string;
  name: string;
  /** Total size in bytes. */
  size: number;
  /** Bytes transferred so far. The percentage is computed from this. */
  uploaded: number;
  status: UploadStatus;
  /** Shown in place of the byte count. Present or absent, never both. */
  error?: string;
};

const units = ["B", "KB", "MB", "GB"] as const;

/** toFixed, not toLocaleString: this renders on the server too. */
function formatBytes(bytes: number): string {
  if (!Number.isFinite(bytes) || bytes <= 0) return "0 B";
  const i = Math.min(Math.floor(Math.log(bytes) / Math.log(1024)), units.length - 1);
  const value = bytes / 1024 ** i;
  return `${value >= 10 || i === 0 ? value.toFixed(0) : value.toFixed(1)} ${units[i]}`;
}

function extensionOf(name: string): string {
  const part = name.split(".").pop();
  return part && part !== name ? part.toUpperCase().slice(0, 4) : "FILE";
}

function percentOf(item: UploadItem): number {
  if (item.size <= 0) return 0;
  return Math.min(100, Math.max(0, Math.round((item.uploaded / item.size) * 100)));
}

function PauseIcon() {
  return (
    <svg width="15" height="15" viewBox="0 0 20 20" fill="none" aria-hidden="true">
      <path d="M7.5 6v8M12.5 6v8" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" />
    </svg>
  );
}

function PlayIcon() {
  return (
    <svg width="15" height="15" viewBox="0 0 20 20" fill="none" aria-hidden="true">
      <path d="m7.8 5.9 6 4.1-6 4.1V5.9Z" fill="currentColor" />
    </svg>
  );
}

function RetryIcon() {
  return (
    <svg width="15" height="15" viewBox="0 0 20 20" fill="none" aria-hidden="true">
      <path
        d="M14.8 7.6A5.5 5.5 0 1 0 15.3 12M14.8 7.6V4.5M14.8 7.6h-3.2"
        stroke="currentColor"
        strokeWidth="1.5"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}



/**
 * The tile carries a tone PER FILE KIND, but each tone is an existing token
 * rather than a new palette: the spreadsheet green is the completion green, the
 * document blue and the image purple are the two ends of the AI gradient, and
 * PDF borrows the clay accent. Six invented colours would have been six pairs
 * to contrast-check in two themes; these five already carry their own on-colour.
 */
const kinds = {
  sheet: { tone: "var(--positive)", on: "var(--on-positive)" },
  doc: { tone: "var(--ai-gradient-from)", on: "var(--on-ai)" },
  pdf: { tone: "var(--accent)", on: "var(--on-accent)" },
  image: { tone: "var(--ai-gradient-to)", on: "var(--on-ai)" },
  other: { tone: "var(--ink-muted)", on: "var(--paper)" },
} as const;

type Kind = keyof typeof kinds;

function kindOf(name: string): Kind {
  const e = extensionOf(name);
  if (["XLS", "XLSX", "CSV", "NUMB"].includes(e)) return "sheet";
  if (["DOC", "DOCX", "TXT", "RTF", "MD"].includes(e)) return "doc";
  if (e === "PDF") return "pdf";
  if (["PNG", "JPG", "JPEG", "WEBP", "GIF", "SVG", "AVIF"].includes(e)) return "image";
  return "other";
}

function FileTile({ name }: { name: string }) {
  const kind = kindOf(name);
  const { tone, on } = kinds[kind];

  return (
    <div
      aria-hidden="true"
      className="upload-tile relative flex h-12 w-10 shrink-0 flex-col justify-between overflow-hidden rounded-lg p-1.5"
      style={{ "--tile": tone, "--tile-on": on } as React.CSSProperties}
    >
      {kind === "sheet" ? (
        <span className="grid grid-cols-2 gap-px">
          {[0, 1, 2, 3].map((cell) => (
            <span key={cell} className="size-1.5 rounded-[1px] bg-current" />
          ))}
        </span>
      ) : (
        <span className="flex flex-col gap-[3px]">
          <span className="h-px w-4 bg-current" />
          <span className="h-px w-3 bg-current" />
          <span className="h-px w-3.5 bg-current" />
        </span>
      )}
      <span className="font-mono text-[8px] leading-none font-semibold tracking-wide">
        {extensionOf(name)}
      </span>
    </div>
  );
}

/** Mounts only when the row completes, so the mount is the cue. */
function DrawnCheck() {
  return (
    <span
      aria-hidden="true"
      className="upload-check grid size-4 shrink-0 place-items-center rounded-full"
      style={{ background: "var(--positive)", color: "var(--on-positive)" }}
    >
      <svg width="11" height="11" viewBox="0 0 20 20" fill="none">
        <path
          d="m5.5 10.3 2.8 2.8 6.2-6.2"
          stroke="currentColor"
          strokeWidth="2.4"
          strokeLinecap="round"
          strokeLinejoin="round"
        />
      </svg>
    </span>
  );
}

function TrashIcon() {
  return (
    <svg width="15" height="15" viewBox="0 0 20 20" fill="none" aria-hidden="true">
      <g stroke="currentColor" strokeWidth="1.4" strokeLinecap="round" strokeLinejoin="round">
        <path d="M3.8 5.6h12.4M8.2 5.6V4.2a1 1 0 0 1 1-1h1.6a1 1 0 0 1 1 1v1.4" />
        <path d="M5.4 5.6 6 15.2a1.4 1.4 0 0 0 1.4 1.3h5.2a1.4 1.4 0 0 0 1.4-1.3l.6-9.6" />
        <path d="M8.6 8.8v4.4M11.4 8.8v4.4" />
      </g>
    </svg>
  );
}

const roundButton =
  "grid size-8 shrink-0 place-items-center rounded-full text-ink-muted transition-colors hover:bg-paper-sunken hover:text-ink";

export function UploadRow({
  item,
  tile = true,
  bytes = true,
  actions = true,
  onPause,
  onResume,
  onRetry,
  onRemove,
  onChange,
  onDownload,
}: {
  item: UploadItem;
  tile?: boolean;
  bytes?: boolean;
  /** Reveal Change / Download once the file lands. */
  actions?: boolean;
  onPause?: (item: UploadItem) => void;
  onResume?: (item: UploadItem) => void;
  onRetry?: (item: UploadItem) => void;
  onRemove?: (item: UploadItem) => void;
  onChange?: (item: UploadItem) => void;
  onDownload?: (item: UploadItem) => void;
}) {
  const nameId = useId();
  const percent = percentOf(item);
  const failed = item.status === "error";
  const done = item.status === "complete";
  // Queued, uploading and paused are all "in flight": each has a known
  // percentage, so each gets a real progressbar.
  const inFlight = !failed && !done;

  const status =
    item.status === "queued"
      ? "Queued"
      : item.status === "uploading"
        ? `Uploading ${percent}%`
        : item.status === "paused"
          ? `Paused ${percent}%`
          : done
            ? "Completed"
            : (item.error ?? "Upload failed");

  return (
    <li className="rounded-2xl bg-paper-raised p-1.5">
      <div className="relative isolate overflow-hidden rounded-xl bg-paper-sunken">
        {inFlight && (
          <span
            aria-hidden="true"
            className="upload-fill -z-10"
            style={{ "--upload-p": percent / 100 } as React.CSSProperties}
          />
        )}

        <div className="flex items-center gap-3.5 px-3.5 py-3">
          {tile && <FileTile name={item.name} />}

          <div className="min-w-0 flex-1">
            <p id={nameId} className="truncate text-[15px] font-medium text-ink">
              {item.name}
            </p>
            <p className="mt-1 flex flex-wrap items-center gap-x-2 gap-y-1 text-[13px]">
              {done && <DrawnCheck />}
              {/* The state is the WORD. Completed and failed are told apart by
                  "Completed" against "Upload failed" and by which control sits
                  beside them — never by colour alone. */}
              <span
                className={cn(
                  "shrink-0",
                  failed ? "text-accent" : inFlight ? "text-[color:var(--ai-gradient-from)]" : "text-ink",
                )}
              >
                {status}
              </span>
              {bytes && !failed && (
                <>
                  <span aria-hidden="true" className="text-ink-faint">
                    •
                  </span>
                  <span className="truncate tabular-nums text-ink-faint">
                    {done
                      ? formatBytes(item.size)
                      : `${formatBytes(item.uploaded)} of ${formatBytes(item.size)}`}
                  </span>
                </>
              )}
            </p>
          </div>

          <div className="flex shrink-0 items-center gap-1">
            {item.status === "uploading" && (
              <button
                type="button"
                onClick={() => onPause?.(item)}
                // The filename is in the label. "Pause upload" is ambiguous the
                // moment there are two rows, which is most of the time.
                aria-label={`Pause ${item.name}`}
                className={roundButton}
              >
                <PauseIcon />
              </button>
            )}
            {(item.status === "paused" || item.status === "queued") && (
              <button
                type="button"
                onClick={() => onResume?.(item)}
                aria-label={`Resume ${item.name}`}
                className={roundButton}
              >
                <PlayIcon />
              </button>
            )}
            {failed && (
              <button
                type="button"
                onClick={() => onRetry?.(item)}
                aria-label={`Retry ${item.name}`}
                className={roundButton}
              >
                <RetryIcon />
              </button>
            )}

            <button
              type="button"
              onClick={() => onRemove?.(item)}
              aria-label={`Remove ${item.name}`}
              className={cn(
                roundButton,
                // Removing is the one destructive control here, so it is the
                // one that wears the accent. It still says what it does.
                "hover:bg-accent-soft hover:text-accent",
              )}
            >
              <TrashIcon />
            </button>
          </div>
        </div>

        {inFlight && (
          <div
            role="progressbar"
            // Labelled by the filename above, so the bar announces which file it
            // belongs to instead of being the fourth unnamed progressbar on the page.
            aria-labelledby={nameId}
            aria-valuemin={0}
            aria-valuemax={100}
            aria-valuenow={percent}
            className="absolute inset-x-0 bottom-0 h-[3px] bg-rule"
          >
            <span
              aria-hidden="true"
              className="upload-bar"
              style={{ "--upload-p": percent / 100 } as React.CSSProperties}
            />
          </div>
        )}
      </div>

      {/* Slides down from behind the card when the file lands. Kept in the DOM
          either way so the transition has two states to move between. */}
      {actions && (
        <div className="upload-actions" data-open={done ? "true" : "false"}>
          <div>
            <div className="flex gap-1.5 pt-1.5">
              <button
                type="button"
                onClick={() => onChange?.(item)}
                // inert while closed, so a collapsed drawer holds nothing the
                // keyboard can land on and nothing a screen reader can reach.
                inert={!done}
                className="flex-1 rounded-lg bg-paper-sunken px-4 py-2 text-[13px] font-medium text-ink transition-colors hover:bg-rule"
              >
                Change
              </button>
              <button
                type="button"
                onClick={() => onDownload?.(item)}
                inert={!done}
                className="flex-1 rounded-lg bg-ink px-4 py-2 text-[13px] font-medium text-paper transition-opacity hover:opacity-85"
              >
                Download
              </button>
            </div>
          </div>
        </div>
      )}
    </li>
  );
}

export function FileUpload({
  items,
  dropzone = true,
  tile = true,
  bytes = true,
  actions = true,
  accept,
  multiple = true,
  maxFiles = 10,
  disabled = false,
  onFilesAdded,
  onPause,
  onResume,
  onRetry,
  onRemove,
  onChange,
  onDownload,
  className,
}: {
  items: UploadItem[];
  dropzone?: boolean;
  tile?: boolean;
  bytes?: boolean;
  actions?: boolean;
  accept?: string;
  multiple?: boolean;
  maxFiles?: number;
  disabled?: boolean;
  onFilesAdded?: (files: File[]) => void;
  onPause?: (item: UploadItem) => void;
  onResume?: (item: UploadItem) => void;
  onRetry?: (item: UploadItem) => void;
  onRemove?: (item: UploadItem) => void;
  onChange?: (item: UploadItem) => void;
  onDownload?: (item: UploadItem) => void;
  className?: string;
}) {
  const input = useRef<HTMLInputElement>(null);
  const [dragging, setDragging] = useState(false);

  const uploaded = items.filter((item) => item.status === "complete").length;

  function add(files: FileList | File[]) {
    if (disabled) return;
    const room = Math.max(0, maxFiles - items.length);
    const next = Array.from(files).slice(0, room);
    if (next.length) onFilesAdded?.(next);
  }

  return (
    <div className={cn("w-full", className)}>
      <style href="file-upload" precedence="default">
        {css}
      </style>

      {dropzone && (
        // A real button, with the file input hidden behind it. Making the input
        // itself the visible control means styling something browsers barely
        // let you style; putting a focusable input NEXT to the button puts two
        // controls in the tab order for one action.
        <button
          type="button"
          disabled={disabled}
          onClick={() => input.current?.click()}
          onDragEnter={(event) => {
            event.preventDefault();
            setDragging(true);
          }}
          onDragOver={(event) => {
            event.preventDefault();
            setDragging(true);
          }}
          onDragLeave={(event) => {
            event.preventDefault();
            setDragging(false);
          }}
          onDrop={(event) => {
            event.preventDefault();
            setDragging(false);
            add(event.dataTransfer.files);
          }}
          className={cn(
            "w-full rounded-xl border border-dashed px-6 py-7 text-center transition-colors",
            dragging
              ? "border-accent bg-accent-soft"
              : "border-control-border bg-paper-raised hover:bg-paper-sunken",
            disabled && "cursor-not-allowed opacity-50",
          )}
        >
          <span className="block text-[15px] text-ink">Drop files here</span>
          <span className="mt-1 block text-[13px] text-ink-muted">or click to browse</span>
        </button>
      )}

      <input
        ref={input}
        type="file"
        className="hidden"
        accept={accept}
        multiple={multiple}
        disabled={disabled}
        tabIndex={-1}
        onChange={(event) => {
          if (event.target.files) add(event.target.files);
          // Cleared so choosing the same file twice fires change twice.
          event.currentTarget.value = "";
        }}
      />

      {items.length > 0 && (
        <ul className={cn("space-y-2.5", dropzone && "mt-3")}>
          {items.map((item) => (
            <UploadRow
              key={item.id}
              item={item}
              tile={tile}
              bytes={bytes}
              actions={actions}
              onPause={onPause}
              onResume={onResume}
              onRetry={onRetry}
              onRemove={onRemove}
              onChange={onChange}
              onDownload={onDownload}
            />
          ))}
        </ul>
      )}

      {/* One summary, not one announcement per row and emphatically not one per
          tick. This string only changes when a file finishes, so that is the
          only time it speaks. */}
      <p role="status" className="sr-only">
        {items.length > 0 ? `${uploaded} of ${items.length} files uploaded` : ""}
      </p>
    </div>
  );
}

/* ---- demo ---------------------------------------------------------------- */

const extras: UploadItem[] = [
  {
    id: "seed-booking",
    name: "booking-export.csv",
    size: 842_000,
    uploaded: 842_000,
    status: "complete",
  },
  {
    id: "seed-brief",
    name: "engagement-brief.pdf",
    size: 2_300_000,
    uploaded: Math.round(2_300_000 * 0.62),
    status: "uploading",
  },
];

function seed(state: UploadStatus, rows: number): UploadItem[] {
  const size = 5_012_000;
  const fraction = state === "complete" ? 1 : state === "error" ? 0.44 : 0.38;
  const first: UploadItem = {
    id: "seed-recon",
    name: "quarterly-reconciliation.xlsx",
    size,
    uploaded: Math.round(size * fraction),
    status: state,
    error: state === "error" ? "Connection lost at 44%" : undefined,
  };
  return [first, ...extras.slice(0, Math.max(0, rows - 1))];
}

function Queue({
  state,
  rows,
  dropzone,
  tile,
  bytes,
  actions,
}: {
  state: UploadStatus;
  rows: number;
  dropzone: boolean;
  tile: boolean;
  bytes: boolean;
  actions: boolean;
}) {
  const [items, setItems] = useState<UploadItem[]>(() => seed(state, rows));
  const timers = useRef<Record<string, ReturnType<typeof setInterval>>>({});
  const nextId = useRef(0);

  // Cleanup only. Nothing sets state from an effect — the React Compiler rules
  // treat that as an error, and every timer here starts from an event handler.
  useEffect(() => {
    const running = timers.current;
    return () => {
      Object.values(running).forEach(clearInterval);
    };
  }, []);

  function stop(id: string) {
    const timer = timers.current[id];
    if (timer) clearInterval(timer);
    delete timers.current[id];
  }

  function run(id: string) {
    stop(id);
    timers.current[id] = setInterval(() => {
      setItems((current) => {
        const item = current.find((entry) => entry.id === id);
        if (!item || item.status !== "uploading") return current;

        const uploaded = Math.min(item.size, item.uploaded + Math.ceil(item.size * 0.08));
        const complete = uploaded >= item.size;
        // Deferred out of the updater: React may call this twice, and clearing
        // an interval inside it would be a side effect running twice. stop() is
        // idempotent, so the microtask is safe either way.
        if (complete) queueMicrotask(() => stop(id));

        return current.map((entry) =>
          entry.id === id
            ? { ...entry, uploaded, status: complete ? "complete" : "uploading" }
            : entry,
        );
      });
    }, 320);
  }

  return (
    <div className="w-full max-w-lg">
      <FileUpload
        items={items}
        dropzone={dropzone}
        tile={tile}
        bytes={bytes}
        actions={actions}
        onFilesAdded={(files) => {
          const added: UploadItem[] = files.map((file) => ({
            // A counter, not crypto.randomUUID(): that is undefined outside a
            // secure context, which includes the plain-http LAN address you
            // test on.
            id: `added-${nextId.current++}`,
            name: file.name,
            size: file.size,
            uploaded: 0,
            status: "uploading",
          }));
          setItems((current) => [...current, ...added]);
          added.forEach((item) => run(item.id));
        }}
        onPause={(target) => {
          stop(target.id);
          setItems((current) =>
            current.map((item) =>
              item.id === target.id ? { ...item, status: "paused" } : item,
            ),
          );
        }}
        onResume={(target) => {
          setItems((current) =>
            current.map((item) =>
              item.id === target.id ? { ...item, status: "uploading" } : item,
            ),
          );
          run(target.id);
        }}
        onRetry={(target) => {
          setItems((current) =>
            current.map((item) =>
              item.id === target.id
                ? { ...item, uploaded: 0, status: "uploading", error: undefined }
                : item,
            ),
          );
          run(target.id);
        }}
        onRemove={(target) => {
          stop(target.id);
          setItems((current) => current.filter((item) => item.id !== target.id));
        }}
      />

      <p className="mt-3 text-[12.5px] leading-relaxed text-ink-faint">
        Seeded rows hold the state the knob picked. Press retry or resume on one, or
        add a file of your own — the fill runs, the check draws itself and the
        actions slide down when it lands.
      </p>
    </div>
  );
}

export default function Demo({
  state = "uploading",
  rows = "2",
  dropzone = true,
  tile = true,
  bytes = true,
  actions = true,
}: {
  state?: UploadStatus;
  rows?: string;
  dropzone?: boolean;
  tile?: boolean;
  bytes?: boolean;
  actions?: boolean;
}) {
  // Keyed on the knobs so changing one re-seeds the queue, while everything
  // inside stays interactive. Deriving that from props in an effect instead is
  // the bug this avoids.
  return (
    <Queue
      key={`${state}-${rows}`}
      state={state}
      rows={Math.max(1, Number(rows) || 1)}
      dropzone={dropzone}
      tile={tile}
      bytes={bytes}
      actions={actions}
    />
  );
}

Next step

Tell me where the business is losing time.

No pitch deck and no discovery-call funnel. Describe the bottleneck and I will tell you plainly whether it is worth building something for, and roughly what that would take.