Redesign alerting UI: severity-colored state and a delivery timeline

AlertStatePill reuses the log-severity color tiers instead of a second
color vocabulary: ok -> quiet, pending -> warn, firing -> critical.
DeliveryTimeline reframes the existing delivery_log data (no new
backend fields) as a vertical timeline -- "why didn't I get paged" is a
chronological question a flat table answered less directly. Rules list
sorts firing-first. The list table's trailing actions column had a
bare empty <th>, which axe-core flags (empty-table-header) -- fixed
with visually-hidden text via app.css's shared .sr-only utility.

web/src/lib/components/AlertStatePill.svelte

@@ -0,0 +1,62 @@
+<script lang="ts">
+	// "Not just a text label — use the severity color system" (Phase 5
+	// task 7). Reuses the same four-tier severity tokens log data uses
+	// (see $lib/severity.ts) rather than inventing a second color
+	// vocabulary for alert state: ok -> quiet, pending -> warn,
+	// firing -> critical. A dot, not just colored text, so state reads
+	// at a glance in a dense rule list, not just on close reading.
+	import type { AlertRuleState } from '$lib/api';
+
+	let { state }: { state: AlertRuleState } = $props();
+
+	const tierFor: Record<AlertRuleState, 'quiet' | 'warn' | 'critical'> = {
+		ok: 'quiet',
+		pending: 'warn',
+		firing: 'critical'
+	};
+</script>
+
+<span class="pill {tierFor[state]}">
+	<span class="dot" aria-hidden="true"></span>
+	{state}
+</span>
+
+<style>
+	.pill {
+		display: inline-flex;
+		align-items: center;
+		gap: var(--space-1);
+		font-family: var(--font-ui);
+		font-size: var(--text-xs);
+		font-weight: var(--font-weight-medium);
+		padding: 0.15rem var(--space-2);
+		border-radius: var(--radius-full);
+		text-transform: capitalize;
+	}
+	.dot {
+		width: 6px;
+		height: 6px;
+		border-radius: 50%;
+	}
+	.quiet {
+		color: var(--color-sev-quiet);
+		background: var(--color-sev-quiet-bg);
+	}
+	.quiet .dot {
+		background: var(--color-sev-quiet);
+	}
+	.warn {
+		color: var(--color-sev-warn);
+		background: var(--color-sev-warn-bg);
+	}
+	.warn .dot {
+		background: var(--color-sev-warn);
+	}
+	.critical {
+		color: var(--color-sev-critical);
+		background: var(--color-sev-critical-bg);
+	}
+	.critical .dot {
+		background: var(--color-sev-critical);
+	}
+</style>

web/src/lib/components/DeliveryTimeline.svelte

@@ -0,0 +1,126 @@
+<script lang="ts">
+	// A firing/resolved delivery log IS a state-transition history --
+	// each row already carries a timestamp and an event_type, which is
+	// exactly a timeline's raw material. No new backend data was needed
+	// for "a timeline view of an alert's state history rather than just
+	// a flat delivery log" (Phase 5 task 7); this is the same
+	// DeliveryLogEntry list the old flat table read, framed differently.
+	import type { DeliveryLogEntry } from '$lib/api';
+
+	let { deliveries }: { deliveries: DeliveryLogEntry[] } = $props();
+
+	function tierFor(d: DeliveryLogEntry): 'critical' | 'quiet' {
+		return d.event_type === 'firing' ? 'critical' : 'quiet';
+	}
+
+	function statusLabel(d: DeliveryLogEntry): string {
+		if (d.status === 'sent') return 'delivered';
+		if (d.status === 'failed') return `failed${d.response_status ? ` (HTTP ${d.response_status})` : ''}`;
+		if (d.status === 'retrying') return `retrying (attempt ${d.attempt_count})`;
+		return d.status;
+	}
+</script>
+
+{#if deliveries.length === 0}
+	<p class="muted">No deliveries yet.</p>
+{:else}
+	<ol class="timeline">
+		{#each deliveries as d (d.id)}
+			<li>
+				<span class="rail">
+					<span class="dot {tierFor(d)}"></span>
+				</span>
+				<div class="entry">
+					<div class="entry-head">
+						<span class="event {tierFor(d)}">{d.event_type}</span>
+						<time>{new Date(d.created_at).toLocaleString()}</time>
+					</div>
+					<div class="entry-body">
+						<span class:danger={d.status === 'failed'}>{statusLabel(d)}</span>
+						{#if d.last_error}<span class="error-text">— {d.last_error}</span>{/if}
+					</div>
+				</div>
+			</li>
+		{/each}
+	</ol>
+{/if}
+
+<style>
+	.muted {
+		color: var(--color-text-muted);
+	}
+	.timeline {
+		list-style: none;
+		margin: 0;
+		padding: 0;
+	}
+	.timeline li {
+		display: grid;
+		grid-template-columns: 1.25rem 1fr;
+		gap: var(--space-3);
+	}
+	.rail {
+		display: flex;
+		flex-direction: column;
+		align-items: center;
+	}
+	.rail::before {
+		content: '';
+		width: 1px;
+		flex: 1;
+		background: var(--color-border);
+	}
+	.timeline li:first-child .rail::before {
+		visibility: hidden;
+	}
+	.dot {
+		width: 10px;
+		height: 10px;
+		border-radius: 50%;
+		flex: none;
+		margin-top: 0.35rem;
+		border: 2px solid var(--color-bg);
+		box-shadow: 0 0 0 1px var(--color-border);
+	}
+	.dot.critical {
+		background: var(--color-sev-critical);
+	}
+	.dot.quiet {
+		background: var(--color-sev-quiet);
+	}
+	.entry {
+		padding-bottom: var(--space-4);
+	}
+	.entry-head {
+		display: flex;
+		align-items: baseline;
+		gap: var(--space-2);
+	}
+	.event {
+		font-weight: var(--font-weight-medium);
+		text-transform: capitalize;
+		font-size: var(--text-sm);
+	}
+	.event.critical {
+		color: var(--color-sev-critical);
+	}
+	.event.quiet {
+		color: var(--color-sev-quiet);
+	}
+	time {
+		font-family: var(--font-mono);
+		font-size: var(--text-xs);
+		color: var(--color-text-muted);
+	}
+	.entry-body {
+		font-size: var(--text-sm);
+		color: var(--color-text-muted);
+		margin-top: var(--space-1);
+	}
+	.danger {
+		color: var(--color-danger);
+	}
+	.error-text {
+		color: var(--color-danger);
+	}
+</style>

web/src/routes/alerts/+page.svelte

@@ -1,5 +1,7 @@
 <script lang="ts">
 	import { listRules, deleteRule, type AlertRule } from '$lib/api';
+	import { Button, Table, EmptyState, Skeleton } from '$lib/components/ui';
+	import AlertStatePill from '$lib/components/AlertStatePill.svelte';
 
 	let rules = $state<AlertRule[]>([]);
 	let loading = $state(true);
@@ -31,102 +33,92 @@
 		const symbols: Record<string, string> = { gt: '>', gte: '>=', lt: '<', lte: '<=', eq: '==', ne: '!=' };
 		return `${symbols[r.comparator ?? ''] ?? r.comparator} ${r.threshold_value}`;
 	}
+
+	// Firing rules first, then pending, then ok -- "what needs my
+	// attention" reads at the top of the list without having to scan
+	// every row (Phase 5 task 7's "at a glance" requirement).
+	const statePriority: Record<AlertRule['state']['state'], number> = { firing: 0, pending: 1, ok: 2 };
+	let sortedRules = $derived([...rules].sort((a, b) => statePriority[a.state.state] - statePriority[b.state.state]));
 </script>
 
 <main>
-	<h1>Alerts</h1>
+	<div class="header">
+		<h1>Alerts</h1>
+		<Button href="/alerts/new" variant="primary">+ New rule</Button>
+	</div>
 	{#if error}<p class="error">Error: {error}</p>{/if}
 
-	<a class="new-rule" href="/alerts/new">+ New rule</a>
-
 	{#if loading}
-		<p>Loading…</p>
+		<div class="skeleton-list">
+			{#each Array(3) as _, i (i)}
+				<Skeleton height="2.5rem" />
+			{/each}
+		</div>
 	{:else if rules.length === 0}
-		<p>No alert rules yet.</p>
+		<EmptyState
+			icon="▲"
+			title="No alert rules yet"
+			description="Rules watch a query on an interval and notify you when it crosses a threshold, or goes silent."
+		>
+			{#snippet action()}
+				<Button href="/alerts/new" variant="primary">+ New rule</Button>
+			{/snippet}
+		</EmptyState>
 	{:else}
-		<table>
+		<Table>
 			<thead>
 				<tr>
+					<th>State</th>
 					<th>Name</th>
 					<th>Condition</th>
-					<th>State</th>
 					<th>Enabled</th>
-					<th></th>
+					<th><span class="sr-only">Actions</span></th>
 				</tr>
 			</thead>
 			<tbody>
-				{#each rules as r (r.id)}
+				{#each sortedRules as r (r.id)}
 					<tr>
-						<td><a href={`/alerts/${r.id}`}>{r.name}</a></td>
-						<td><code>{conditionSummary(r)}</code></td>
 						<td>
-							<span class="state" class:firing={r.state.state === 'firing'} class:pending={r.state.state === 'pending'}>
+							<AlertStatePill state={r.state.state} />
-								{r.state.state}
-							</span>
 							{#if r.state.last_eval_status === 'error'}
 								<span class="eval-error" title={r.state.last_error}>eval error</span>
 							{/if}
 						</td>
+						<td><a href={`/alerts/${r.id}`}>{r.name}</a></td>
+						<td><code>{conditionSummary(r)}</code></td>
 						<td>{r.enabled ? 'yes' : 'no'}</td>
-						<td><button class="delete" onclick={() => remove(r.id)}>Delete</button></td>
+						<td><Button size="sm" variant="danger" onclick={() => remove(r.id)}>Delete</Button></td>
 					</tr>
 				{/each}
 			</tbody>
-		</table>
+		</Table>
 	{/if}
 </main>
 
 <style>
 	main {
-		font-family: system-ui, sans-serif;
+		max-width: 60rem;
-		max-width: 960px;
+	}
-		margin: 2rem auto;
+	.header {
-		padding: 0 1rem;
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+		margin-bottom: var(--space-4);
+	}
+	h1 {
+		font-size: var(--text-xl);
 	}
 	.error {
-		color: #b00020;
+		color: var(--color-danger);
 	}
-	.new-rule {
+	.skeleton-list {
-		display: inline-block;
+		display: flex;
-		margin-bottom: 1rem;
+		flex-direction: column;
-		color: #06c;
+		gap: var(--space-2);
-		text-decoration: none;
-	}
-	table {
-		border-collapse: collapse;
-		width: 100%;
-	}
-	th,
-	td {
-		border-bottom: 1px solid #eee;
-		padding: 0.4rem 0.6rem;
-		text-align: left;
-		font-size: 0.9rem;
-	}
-	.state {
-		font-size: 0.75rem;
-		padding: 0.1rem 0.5rem;
-		border-radius: 1rem;
-		background: #eee;
-	}
-	.state.pending {
-		background: #ffe9b3;
-	}
-	.state.firing {
-		background: #fdd;
-		color: #900;
 	}
 	.eval-error {
-		margin-left: 0.4rem;
+		margin-left: var(--space-2);
-		font-size: 0.75rem;
+		font-size: var(--text-xs);
-		color: #b00020;
+		color: var(--color-danger);
-	}
-	.delete {
-		color: #b00020;
-		background: none;
-		border: 1px solid #b00020;
-		border-radius: 4px;
-		padding: 0.15rem 0.5rem;
-		cursor: pointer;
 	}
 </style>

web/src/routes/alerts/[id]/+page.svelte

@@ -1,6 +1,9 @@
 <script lang="ts">
 	import { page } from '$app/state';
 	import { getRule, deleteRule, listDeliveries, type AlertRule, type DeliveryLogEntry } from '$lib/api';
+	import { Button } from '$lib/components/ui';
+	import AlertStatePill from '$lib/components/AlertStatePill.svelte';
+	import DeliveryTimeline from '$lib/components/DeliveryTimeline.svelte';
 
 	const ruleId = page.params.id!;
 
@@ -43,7 +46,7 @@
 	{:else}
 		<div class="header">
 			<h1>{rule.name}</h1>
-			<button class="delete" onclick={remove}>Delete rule</button>
+			<Button variant="danger" onclick={remove}>Delete rule</Button>
 		</div>
 		{#if rule.description}<p class="desc">{rule.description}</p>{/if}
 		{#if error}<p class="error">Error: {error}</p>{/if}
@@ -51,13 +54,7 @@
 		<section class="summary">
 			<div>
 				<span class="label">State</span>
-				<span
+				<AlertStatePill state={rule.state.state} />
-					class="state"
-					class:firing={rule.state.state === 'firing'}
-					class:pending={rule.state.state === 'pending'}
-				>
-					{rule.state.state}
-				</span>
 			</div>
 			<div><span class="label">Condition</span> {rule.condition_type} — {conditionSummary(rule)}</div>
 			<div><span class="label">Query</span> <code>{rule.query}</code></div>
@@ -74,45 +71,15 @@
 			{/if}
 		</section>
 
-		<h2>Delivery log</h2>
+		<h2>State history</h2>
 		<p class="hint">Most recent first — this is "why didn't I get paged."</p>
-		{#if deliveries.length === 0}
+		<DeliveryTimeline {deliveries} />
-			<p>No deliveries yet.</p>
-		{:else}
-			<table>
-				<thead>
-					<tr>
-						<th>When</th>
-						<th>Event</th>
-						<th>Status</th>
-						<th>Attempts</th>
-						<th>Response</th>
-						<th>Error</th>
-					</tr>
-				</thead>
-				<tbody>
-					{#each deliveries as d (d.id)}
-						<tr>
-							<td>{new Date(d.created_at).toLocaleString()}</td>
-							<td>{d.event_type}</td>
-							<td>{d.status}</td>
-							<td>{d.attempt_count}</td>
-							<td>{d.response_status ?? '—'}</td>
-							<td class="error-cell">{d.last_error ?? ''}</td>
-						</tr>
-					{/each}
-				</tbody>
-			</table>
-		{/if}
 	{/if}
 </main>
 
 <style>
 	main {
-		font-family: system-ui, sans-serif;
+		max-width: 56rem;
-		max-width: 900px;
-		margin: 2rem auto;
-		padding: 0 1rem;
 	}
 	.header {
 		display: flex;
@@ -120,69 +87,31 @@
 		justify-content: space-between;
 	}
 	.desc {
-		color: #555;
+		color: var(--color-text-muted);
 	}
 	.error {
-		color: #b00020;
+		color: var(--color-danger);
 	}
 	.summary {
-		border: 1px solid #ddd;
+		border: 1px solid var(--color-border);
-		border-radius: 6px;
+		border-radius: var(--radius-md);
-		padding: 0.75rem 1rem;
+		padding: var(--space-3) var(--space-4);
-		margin: 1rem 0;
+		margin: var(--space-4) 0;
 		display: flex;
 		flex-direction: column;
-		gap: 0.4rem;
+		gap: var(--space-1);
-		font-size: 0.9rem;
+		font-size: var(--text-base);
+		background: var(--color-surface);
 	}
 	.label {
-		font-weight: 600;
+		font-weight: var(--font-weight-medium);
-		margin-right: 0.4rem;
+		margin-right: var(--space-1);
-	}
-	.state {
-		font-size: 0.75rem;
-		padding: 0.1rem 0.5rem;
-		border-radius: 1rem;
-		background: #eee;
-	}
-	.state.pending {
-		background: #ffe9b3;
-	}
-	.state.firing {
-		background: #fdd;
-		color: #900;
 	}
 	.eval-error {
-		color: #b00020;
+		color: var(--color-danger);
 	}
 	.hint {
-		font-size: 0.8rem;
+		font-size: var(--text-sm);
-		color: #777;
+		color: var(--color-text-muted);
-	}
-	.delete {
-		color: #b00020;
-		background: none;
-		border: 1px solid #b00020;
-		border-radius: 4px;
-		padding: 0.15rem 0.5rem;
-		cursor: pointer;
-	}
-	table {
-		border-collapse: collapse;
-		width: 100%;
-	}
-	th,
-	td {
-		border-bottom: 1px solid #eee;
-		padding: 0.3rem 0.5rem;
-		text-align: left;
-		font-size: 0.85rem;
-	}
-	.error-cell {
-		color: #b00020;
-		max-width: 20rem;
-		overflow: hidden;
-		text-overflow: ellipsis;
-		white-space: nowrap;
 	}
 </style>

web/src/routes/alerts/new/+page.svelte

@@ -193,49 +193,48 @@
 
 <style>
 	main {
-		font-family: system-ui, sans-serif;
+		max-width: 45rem;
-		max-width: 720px;
-		margin: 2rem auto;
-		padding: 0 1rem;
 	}
 	.error {
-		color: #b00020;
+		color: var(--color-danger);
 	}
 	.field {
 		display: block;
-		margin-bottom: 0.75rem;
+		margin-bottom: var(--space-3);
-		font-size: 0.85rem;
+		font-size: var(--text-sm);
+		color: var(--color-text-muted);
 	}
 	.field input {
 		display: block;
 		width: 100%;
 		box-sizing: border-box;
-		margin-top: 0.2rem;
+		margin-top: var(--space-1);
 	}
 	.hint {
-		font-size: 0.8rem;
+		font-size: var(--text-sm);
-		color: #777;
+		color: var(--color-text-muted);
 	}
 	.row {
 		display: flex;
-		gap: 1rem;
+		gap: var(--space-4);
 		align-items: flex-end;
-		margin: 1rem 0;
+		margin: var(--space-4) 0;
 		flex-wrap: wrap;
 	}
 	.row label {
-		font-size: 0.85rem;
+		font-size: var(--text-sm);
+		color: var(--color-text-muted);
 		display: flex;
 		flex-direction: column;
-		gap: 0.2rem;
+		gap: var(--space-1);
 	}
 	.new-target {
 		display: flex;
-		gap: 0.5rem;
+		gap: var(--space-2);
-		margin-bottom: 1rem;
+		margin-bottom: var(--space-4);
 	}
 	.submit {
-		margin-top: 1rem;
+		margin-top: var(--space-4);
-		padding: 0.4rem 1rem;
+		padding: var(--space-2) var(--space-4);
 	}
 </style>