---
name: datetime
description: Use when implementing or debugging code that uses @suaveplan/datetime: Timezone-aware date/time utilities with business-day arithmetic, recurrence rules, calendar math, and relative time formatting.
---

# @suaveplan/datetime

Timezone-aware date/time utilities covering the most common application-layer date operations that the native `Date` API leaves unaddressed. The package provides calendar math (`addDuration`, `subtractDuration`, `startOf`, `endOf`, `getCalendarMonth`, leap-year detection), business-day arithmetic with configurable holiday calendars and custom weekend definitions, an RRULE-subset recurrence engine (DAILY/WEEKLY/MONTHLY/YEARLY with BYDAY/BYMONTH/COUNT/UNTIL), and human-readable relative time formatting (`"3 hours ago"`, `"in 2 days"`). All stateful entry points accept an injectable `Clock` for deterministic testing. Use this package for scheduling UIs, calendar components, invoice date calculations, and any domain where "next business day" or "every other Monday" has real meaning. For low-level stopwatches, throttle/debounce, or vector clocks use `@suaveplan/timing`.

## When to use this skill

- Implementing or debugging code that imports `@suaveplan/datetime`.
- The task touches: see package README.
- You need API guidance for this package's exports.

## Quick reference

```ts
import { /* see API Reference below */ } from "@suaveplan/datetime";
```

## Dependencies

Workspace dependencies: `@suaveplan/error`, `@suaveplan/types`

## Where to read more

This skill is intentionally short. The package's own documentation is the authoritative source — read these in order:

1. **`packages/foundation/datetime/README.md`** — overview, install, quick-start, module index
2. **`packages/foundation/datetime/src/**/*.md`** — co-located docs per implementation file (Purpose, Features, Basic + Advanced examples, full API reference, Implementation notes — all packages  ship ≥200 words per module)
3. **`packages/foundation/datetime/package.json`** `exports` map — every subpath you can import from

When the user asks an API question, read the relevant co-located `.md` first; do not answer from training-data memory.

## See also

- `@suaveplan/error`
- `@suaveplan/types`

---

_This SKILL.md is auto-generated by `suaveplan-skills/scripts/generate-skills.ts` from the package's README. Do not edit by hand — re-run the generator after the README changes._