Hearth / Design system / Implementation
Build with AI.
Give the next pair of hands a good set of instructions.
Shared component contracts, a reusable brief, and a working example. The same guidance supports the documentation you read and the code an assistant helps you write.
Generated from the component registry. Updated with every development start and production build.
A small, repeatable workflow.
Find the contract
Read when to use a component, when to avoid it, and its live states before choosing it.
Compose what exists
Use the existing components and tokens. Record a missing requirement before adding a variant.
Keep decisions in the engine
Pass evaluated outcomes through unchanged. The interface presents the result and the reason behind it.
Check the result
Verify behaviour, keyboard access, narrow layouts, and both themes. Report the checks that actually ran.
Start with a clear brief.
This is the request used for the example below. It names the job, the boundaries, and what a finished result must demonstrate.
Copy this brief into your coding assistant.
Worked example
From a brief to a household recap.
A fixed example of the original grocery note on Wednesday morning. Follow a reason back to the contract, or read the open question and the latest itemised receipt from work done on its own.
Groceries / The week of Aug 24
A little household catch-up.
As of Wednesday, Aug 26 at 9:30 am
Can spend up to $40 at a time and $120 a week without asking. Will ask about 2 things. 2 hard limits.
Latest activity
Tue, Aug 25
11:15 amRefused
Add a bottle of Pinot Noir
Greenleaf's "pairs well with" suggestion for the salmon in Wednesday's order.
Wed, Aug 26
7:00 amWaiting on you
Reorder laundry detergent, the 5-litre size
The big bottle from Valley Wholesale works out 30% cheaper per wash than the one you usually get, but it's a bigger order than usual.
8:15 amDone
Move today's delivery to 7–9 pm
Greenleaf dropped the 5–7 pm slot. 7–9 pm is the next one today and nobody's out this evening.
Needs you
7:00 amThe 5-litre detergent from Valley Wholesale is $55.00. Go ahead?
Sent through a card in the app on Wednesday, Aug 26 at 7:00 am.
If there is no answer by Thursday, Aug 27 at 7:00 am, it will let this go.
Latest itemised receipt · Done on its own
Reorder coffee beans and dish soap
Done on its own, Tuesday, Aug 25 at 6:50 am
- Coffee beans, 12 oz$18.99
- Dish soap, 25 oz$4.76
- Total$23.75
Coffee lasts about ten days and the last bag was opened on the 14th. Dish soap is on the same rhythm.
The decisions behind the composition.
- RiskSummary
- Explains what the supplied note permits, using summarize(contract).
- TraceEvent
- Shows each recent attempt with its status at the snapshot time.
- ApprovalCard
- Explains the open question and its engine-supplied deadline. No answer handlers are passed.
- Receipt
- Itemises work done on its own and explains when a receipt would have stayed quiet.
- ContractLink
- Connects each outcome to the specific line in the note that governed it.
One small composition brings these patterns together. The engine selects the snapshot after evaluating the complete week, so earlier spending still informs later limits.
Read the composition source
This is the file rendered above, read directly at build time.
import type { Template } from "@/lib/contract/schema";
import { activityRecap, describeLink, evaluate, formatDateTime, formatDay, statusAt, summarize } from "@/lib/engine";
import { contractHref } from "@/lib/routes";
import { ApprovalCard, Receipt, RiskSummary, TraceEvent, cx } from "@/design-system";
export interface ActivityRecapProps {
template: Template;
/** Fixed snapshot instant, parsed by the engine. Never the browser clock. */
now: number;
className?: string;
}
/** A read-only composition of the existing activity patterns, using the supplied note. */
export function ActivityRecap({ template, now, className }: ActivityRecapProps) {
const run = evaluate(template.contract, template.fixture);
const recap = activityRecap(run, now);
const editorHref = contractHref(template.id);
return (
<section aria-label={`${template.runs} activity recap`} className={cx("min-w-0 rounded-lg border border-line bg-surface p-4 sm:p-6", className)}>
<header className="border-b border-line pb-5">
<p className="text-xs font-medium uppercase tracking-wide text-ink-2">{template.runs} / {template.fixture.title}</p>
<h3 className="mt-2 font-display text-2xl">A little household catch-up.</h3>
<p className="mt-2 text-sm text-ink-2 tnum">As of {formatDateTime(now)}</p>
<div className="mt-4"><RiskSummary summary={summarize(template.contract)} variant="compact" /></div>
</header>
{recap.empty ? <p className="py-6 text-ink-2">{recap.emptyMessage}</p> : (
<div className="mt-5 grid min-w-0 gap-6 xl:grid-cols-2">
<div className="min-w-0">
<h4 className="text-xs font-medium uppercase tracking-wide text-ink-2">Latest activity</h4>
{recap.groups.map(({ day, events }) => (
<div key={day} className="mt-4">
<p className="border-b border-line pb-2 text-sm text-ink-2">{formatDay(day)}</p>
{events.map((event) => <TraceEvent key={event.id} event={event} status={statusAt(event, now)} link={describeLink(event, template.contract)} linkHref={editorHref} />)}
</div>
))}
</div>
<div className="grid min-w-0 content-start gap-5">
{recap.openAsk ? <ApprovalCard event={recap.openAsk} escalation={template.contract.escalation} now={now} link={describeLink(recap.openAsk, template.contract)} linkHref={editorHref} /> : null}
{recap.unattendedReceipt ? (
<div>
<h4 className="mb-3 text-xs font-medium uppercase tracking-wide text-ink-2">Latest itemised receipt · Done on its own</h4>
<Receipt event={recap.unattendedReceipt} policy={template.contract.receipts} link={describeLink(recap.unattendedReceipt, template.contract)} linkHref={editorHref} />
</div>
) : null}
</div>
</div>
)}
</section>
);
}
Make the result reviewable.
The guide provides instructions. Verification checks what was actually built. Open the source, inspect each state, and reproduce the checks.
- Behaviour: engine tests cover future activity, open-question timing, empty periods, and changed notes.
- Design tokens: a focused audit flags literal colours and unsupported typography in the checked source. It does not prove component reuse or visual quality.
- Interaction: browser checks exercise clipboard success and fallback, keyboard contract links, documented states, and narrow layouts in both themes.
- Accessibility: automated checks accompany visual and keyboard review. A human screen-reader review remains useful.