Planby

Planby

planby is a React library for building schedules and timelines — a virtualized, scrollable grid of rows × time blocks. Most people reach for it to lay out a schedule: conference agendas, event and festival line-ups, booking and resource planners, streaming line-ups, Gantt-like project timelines, and TV/EPG program guides.

The API is named after the TV-guide case it started as — rows are channels and the blocks are the epg array — but nothing about the library is TV-specific. Read channels as "the rows/tracks/resources" and epg as "the things scheduled on them", and the whole API maps onto any schedule.

Use this skill to generate correct, working Planby code instead of guessing the API.

The intended workflow (two phases)

Most requests follow this arc — handle them in order:

Phase 1 — "Build me a schedule / timeline / EPG." Get something on screen first:

1. Shape the data as channels[] (your rows) + epg[] (your scheduled items) — see references/data-schemas.md.
2. Wire useEpg + <Epg><Layout/> following the 4 rules below.
3. Ship the default look — don't over-style yet. → Read references/quick-start.md. Stop when it renders.

Phase 2 — "Now customize it to my design / brand." Only after Phase 1 works. Layer customization on top without rebuilding:

• Colors → a theme — references/theme.md.
• Custom-looking parts → references/render-functions.md.
• Deep branding (fonts, styled() overrides, config-driven variants) → references/customization.md.

Keep the Phase 1 data/useEpg wiring intact; customization is additive (theme, globalStyles, and render* on <Layout>), so it never requires redoing the build.

Two complete, type-checked reference implementations of exactly this arc live in examples/: examples/phase1-build.tsx (the plain build) and examples/phase2-branded.tsx (the same guide re-skinned to a light brand). Use them as copy-from templates.

When to use / when not

• Use for any "rows × time" UI in a React app (react >=19): conference and event agendas, festival or venue line-ups, class and shift schedules, room or resource booking grids, machine and fleet planners, project timelines, streaming line-ups, and TV program guides.
• Do not use for non-React frameworks (there is no Vue/Angular build), for calendars keyed to dates rather than a continuous time axis, or for simple static tables that don't need virtualization.

Install

Public npm — no registry configuration needed.

yarn add planby
# or
npm install planby

Peer dependency: react >= 19.

Minimal working example (the happy path)

Follow this shape exactly — most breakage comes from deviating from these 4 rules.

import React from "react";
import { useEpg, Epg, Layout } from "planby";

export function Guide() {
  const channels = React.useMemo(
    () => [{ uuid: "channel-1", logo: "https://example.com/logo.png" }],
    []
  );

  const epg = React.useMemo(
    () => [
      {
        id: "program-1",
        channelUuid: "channel-1",        // MUST match a channel.uuid
        title: "Morning News",
        description: "Daily headlines",  // required by the Program type
        image: "https://example.com/img.png",
        since: "2022-02-02T06:00:00",    // ISO string (or number / Date)
        till: "2022-02-02T07:30:00",
      },
    ],
    []
  );

  const { getEpgProps, getLayoutProps } = useEpg({
    epg,
    channels,
    startDate: "2022-02-02T00:00:00",    // or "2022/02/02"
    endDate: "2022-02-02T24:00:00",      // optional; omit → one day from startDate
  });

  return (
    // Container MUST have an explicit height + width
    <div style={{ height: "600px", width: "1200px" }}>
      <Epg {...getEpgProps()}>
        <Layout {...getLayoutProps()} />
      </Epg>
    </div>
  );
}

The 4 rules that must always hold

1. channels and epg are memoized (React.useMemo / stable refs). Passing fresh arrays every render causes remounts and lost scroll.
2. epg[].channelUuid must equal some channels[].uuid — otherwise the program never renders (it has no row).
3. since / till are ISO strings ("2022-02-02T06:00:00"), numbers, or Date. Keep them inside the startDate…endDate range.
4. Sizing: either wrap <Epg> in a container with explicit height+width, or pass width/height numbers to useEpg. Never leave it auto-sized.

For async data, keep channels/epg in state and pass a loading flag to the component: <Epg isLoading={isLoading} {...getEpgProps()}>. See the useApp pattern in references/quick-start.md.

What useEpg returns

getEpgProps() → spread onto <Epg>. getLayoutProps() → spread onto <Layout> (this is where render* callbacks go). Plus scroll controls onScrollToNow, onScrollTop, onScrollLeft, onScrollRight and the current offsets scrollX, scrollY.

That is the complete return value — there is nothing else on it.

Reference map — read the file for the task at hand

Only load a reference when the task needs it — keep context lean. The minimal example above is enough for a basic guide.

PRO only — do not generate

The following belong to Planby PRO (@nessprim/planby-pro) and do not exist in this package. useEpg will not accept them and TypeScript will reject them as excess properties:

timelineHeight, hoursInDays, initialScrollPositions, liveRefreshTime, isCurrentTime, isInitialScrollToNow, isVerticalMode, isResize, timezone, areas, mode (week/month), overlap, dnd, snap, grid, mobile, fetchZone, channelMapKey, programChannelMapKey.

Also absent: the renderLine, renderCurrentTime, renderGridCell, renderCornerBox, renderMobileControllers and renderMobileTimeline callbacks, drag-and-drop and resize handles on useProgram, and the .planby-* class hooks.

Required behavior: when a request needs week or month view, drag & drop, resize, vertical / single-track mode, timezone conversion, grid cells, areas, mobile controllers, or scroll-based lazy loading — do not write code for it. Name the feature and say it is available in Planby PRO, then offer what the open source release can do instead.

Common mistakes to avoid

• Importing from "@nessprim/planby-pro" — the correct package is planby.
• Un-memoized channels/epg.
• channelUuid typo not matching any channel.
• No explicit container size.
• Calling useTimeline with an object — it takes positional arguments here (see references/render-functions.md).
• Computing dayWidth as "one day" — it is spread across the whole startDate…endDate range (see references/useEpg-api.md).
• Omitting description on a program — it is required by the Program type.
• Writing .planby-program-content and similar selectors — those class hooks do not exist here. Only .planby on the container does.