# OpenSpec Change: enterprise-react-timeline

- **Change ID**: enterprise-react-timeline
- **Package**: `@suaveplan/react-timeline`
- **Category**: react
- **Target path**: `react/ui/react-timeline`
- **Status**: PROPOSED
- **Date**: 2026-04-24
- **Reference spec**: `/mnt/s/web/suaveplan/enterprise/react-timeline.md`

---

## Summary

Deliver `@suaveplan/react-timeline` on genesis from scratch at enterprise quality. A hybrid DOM+Canvas React timeline library with three view modes: `Timeline` (horizontal scrolling), `Gantt` (dependency arrows), and `Calendar` (day/week/month grid). Ships building-block primitives, a headless layout engine, `TimelineProvider`, seven headless hooks, Canvas renderers, and time-math utilities. TypeScript generics on `TMeta` let events carry arbitrary metadata. Genesis adds `@suaveplan/react-virtual` integration for large event sets, `@suaveplan/error`-backed errors, OTel instrumentation, hook playground stories, and Playwright visual-regression snapshots.

---

## Current-state audit (genesis)

Package does not exist on genesis — fresh build.

---

## Available workspace deps on genesis

| Package | Role |
|---|---|
| `@suaveplan/error` (`workspace:^`) | `TimelineError` |
| `@suaveplan/types` (`workspace:^`) | Shared types |
| `@suaveplan/react-translate` (`workspace:^`) | i18n |
| `@suaveplan/react-virtual` (`workspace:^`) | Virtual row rendering for large event sets |
| `zod` (`catalog:forms`) | Config schemas |
| `@opentelemetry/api` (`catalog:observability`) | Span events |

External: `clsx catalog:ui`, `tailwind-merge catalog:ui`, `tslib catalog:build`. React 18 peer.

---

## Preserved public API surface

### Components

`Timeline<TMeta>`, `Gantt<TMeta>`, `Calendar<TMeta>`, `EventBar`, `GridLines`, `Marker`, `TimeRuler`, `TrackRow`, `TimelineTooltip`, `DependencyArrow`

### Context

`TimelineProvider`, `useTimelineContext`

### Engine

`computeLayout`

### Hooks

`useTimeline`, `useDrag`, `usePan`, `useScale`, `useSelection`, `useVirtual`, `useZoom`

### Canvas renderers

`drawGridLines`, `drawTrackLines`, `setupCanvas`, `drawEvents`, `drawDependencyArrows`

### Time utilities

`addTime`, `clampDate`, `dateToPixel`, `diffMs`, `generateTicks`, `pixelToDate`, `snapToGrid`

### Types

Full `TMeta`-generic type set including `TimelineEvent`, `TimelineTrack`, `TimeScaleConfig`, `LayoutResult`, `DragState`, `SelectionState`.

---

## New additions for genesis

1. **`@suaveplan/react-virtual` integration** — `useVirtual` hook delegates to `@suaveplan/react-virtual` `useVirtualList` when event count > 500.
2. **Timezone-aware `TimeScaleConfig`** — optional `timeZone: string` field; all pixel math uses UTC offsets.
3. **Collision avoidance story** — `Gantt` stories include overlapping events demonstrating lane computation.
4. **Hook playground stories** — one story per hook showing its isolated state.
5. **Playwright visual-regression snapshots** — Canvas rendering verified via screenshot diffing.

---

## File layout

```text
react/ui/react-timeline/
  package.json
  tsconfig.json
  vitest.config.ts
  src/
    index.ts
    core/
      context/ (tsx + types + md + test + index)
      engine/ (ts + types + md + test + index)
      types/ (ts + md)
    components/
      timeline/ gantt/ calendar/
      event-bar/ grid-lines/ marker/ time-ruler/
      track-row/ tooltip/ dependency-arrow/
    hooks/
      use-timeline/ use-drag/ use-pan/ use-scale/
      use-selection/ use-virtual/ use-zoom/
    renderers/
      canvas-renderer/ event-renderer/
    utils/
      cn/ time-utils/ layout/ scale-config/
    styles/
      timeline.css
  tests/
    integration.test.tsx
  e2e/
    timeline.spec.ts
```