feat(TRUEREF-0016): implement web UI search explorer

- Two-step search workflow: resolve library then query documentation
- URL state sync (/search?lib=...&q=...)
- LibraryResult, SnippetCard, SearchInput components
- Code/info snippet display with breadcrumbs and token counts
- Copy-as-markdown button for full response

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/components/search/LibraryResult.svelte

@@ -0,0 +1,33 @@
+<script lang="ts">
+	let {
+		result,
+		onSelect
+	}: {
+		result: {
+			id: string;
+			title: string;
+			description: string | null;
+			totalSnippets: number | null;
+			trustScore: number | null;
+		};
+		onSelect: (id: string) => void;
+	} = $props();
+
+	const snippetCount = $derived(result.totalSnippets ?? 0);
+	const trust = $derived(result.trustScore ?? 0);
+</script>
+
+<button
+	onclick={() => onSelect(result.id)}
+	class="w-full rounded-xl border border-gray-200 bg-white p-4 text-left shadow-sm transition-all hover:border-blue-300 hover:shadow-md"
+>
+	<div class="flex items-center justify-between">
+		<span class="font-semibold text-gray-900">{result.title}</span>
+		<span class="text-xs text-gray-400">Trust {trust.toFixed(1)}/10</span>
+	</div>
+	<p class="font-mono text-xs text-gray-400">{result.id}</p>
+	{#if result.description}
+		<p class="mt-1.5 line-clamp-2 text-sm text-gray-600">{result.description}</p>
+	{/if}
+	<p class="mt-2 text-xs text-gray-400">{snippetCount.toLocaleString()} snippets</p>
+</button>

src/lib/components/search/SearchInput.svelte

@@ -0,0 +1,56 @@
+<script lang="ts">
+	let {
+		value = $bindable(''),
+		placeholder = 'Search...',
+		onsubmit,
+		loading = false
+	}: {
+		value?: string;
+		placeholder?: string;
+		onsubmit: () => void;
+		loading?: boolean;
+	} = $props();
+
+	function handleKeydown(event: KeyboardEvent) {
+		if (event.key === 'Enter') {
+			onsubmit();
+		}
+	}
+</script>
+
+<div class="flex gap-2">
+	<input
+		type="text"
+		bind:value
+		{placeholder}
+		onkeydown={handleKeydown}
+		disabled={loading}
+		class="flex-1 rounded-lg border border-gray-200 bg-white px-4 py-2.5 text-sm text-gray-900 placeholder-gray-400 shadow-sm outline-none transition-all focus:border-blue-400 focus:ring-2 focus:ring-blue-100 disabled:cursor-not-allowed disabled:opacity-60"
+	/>
+	<button
+		onclick={onsubmit}
+		disabled={loading || !value.trim()}
+		class="rounded-lg bg-blue-600 px-4 py-2.5 text-sm font-medium text-white shadow-sm transition-colors hover:bg-blue-700 disabled:cursor-not-allowed disabled:opacity-50"
+	>
+		{#if loading}
+			<span class="inline-flex items-center gap-1.5">
+				<svg
+					class="h-4 w-4 animate-spin"
+					viewBox="0 0 24 24"
+					fill="none"
+					stroke="currentColor"
+					stroke-width="2"
+				>
+					<path
+						stroke-linecap="round"
+						stroke-linejoin="round"
+						d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15"
+					/>
+				</svg>
+				Searching
+			</span>
+		{:else}
+			Search
+		{/if}
+	</button>
+</div>

src/lib/components/search/SnippetCard.svelte

@@ -0,0 +1,55 @@
+<script lang="ts">
+	import type { SnippetJson } from '$lib/server/api/formatters';
+
+	let { snippet }: { snippet: SnippetJson } = $props();
+
+	const isCode = $derived(snippet.type === 'code');
+
+	const title = $derived(
+		snippet.type === 'code' ? snippet.title : null
+	);
+
+	const breadcrumb = $derived(
+		snippet.type === 'code' ? snippet.description : snippet.breadcrumb
+	);
+
+	const content = $derived(
+		snippet.type === 'code' ? snippet.codeList[0]?.code ?? '' : snippet.text
+	);
+
+	const language = $derived(
+		snippet.type === 'code' ? (snippet.codeList[0]?.language ?? '') : null
+	);
+
+	const tokenCount = $derived(snippet.tokenCount ?? 0);
+</script>
+
+<div class="overflow-hidden rounded-xl border border-gray-200 bg-white">
+	<div class="flex items-center justify-between border-b border-gray-100 px-4 py-2.5">
+		<div class="flex items-center gap-2">
+			{#if isCode}
+				<span class="rounded bg-purple-100 px-1.5 py-0.5 text-xs text-purple-700">code</span>
+			{:else}
+				<span class="rounded bg-blue-100 px-1.5 py-0.5 text-xs text-blue-700">info</span>
+			{/if}
+			{#if title}
+				<span class="text-sm font-medium text-gray-800">{title}</span>
+			{/if}
+		</div>
+		<span class="text-xs text-gray-400">{tokenCount} tokens</span>
+	</div>
+
+	{#if breadcrumb}
+		<p class="bg-gray-50 px-4 py-1.5 text-xs italic text-gray-500">{breadcrumb}</p>
+	{/if}
+
+	<div class="p-4">
+		{#if isCode}
+			<pre
+				class="overflow-x-auto rounded bg-gray-950 p-4 text-sm text-gray-100"
+			><code>{content}</code></pre>
+		{:else}
+			<div class="prose prose-sm max-w-none whitespace-pre-wrap text-gray-700">{content}</div>
+		{/if}
+	</div>
+</div>

src/lib/utils/copy-to-clipboard.ts

@@ -0,0 +1,36 @@
+/**
+ * Copy text to the system clipboard.
+ *
+ * Falls back gracefully when the Clipboard API is unavailable (e.g. non-HTTPS
+ * or older browsers) by using a temporary textarea element.
+ *
+ * @returns true when the copy succeeded, false otherwise.
+ */
+export async function copyToClipboard(text: string): Promise<boolean> {
+	if (typeof navigator === 'undefined') return false;
+
+	if (navigator.clipboard?.writeText) {
+		try {
+			await navigator.clipboard.writeText(text);
+			return true;
+		} catch {
+			// Fall through to legacy path.
+		}
+	}
+
+	// Legacy fallback via execCommand.
+	try {
+		const textarea = document.createElement('textarea');
+		textarea.value = text;
+		textarea.style.position = 'fixed';
+		textarea.style.opacity = '0';
+		document.body.appendChild(textarea);
+		textarea.focus();
+		textarea.select();
+		const ok = document.execCommand('copy');
+		document.body.removeChild(textarea);
+		return ok;
+	} catch {
+		return false;
+	}
+}

src/routes/search/+page.svelte

@@ -0,0 +1,292 @@
+<script lang="ts">
+	import { onMount } from 'svelte';
+	import { goto } from '$app/navigation';
+	import { page } from '$app/stores';
+	import { get } from 'svelte/store';
+	import LibraryResult from '$lib/components/search/LibraryResult.svelte';
+	import SnippetCard from '$lib/components/search/SnippetCard.svelte';
+	import SearchInput from '$lib/components/search/SearchInput.svelte';
+	import { copyToClipboard } from '$lib/utils/copy-to-clipboard';
+	import type { LibrarySearchJsonResult, SnippetJson } from '$lib/server/api/formatters';
+
+	// ---------------------------------------------------------------------------
+	// State
+	// ---------------------------------------------------------------------------
+
+	let libraryName = $state('');
+	let selectedLibraryId = $state<string | null>(null);
+	let selectedLibraryTitle = $state<string | null>(null);
+	let query = $state('');
+
+	let libraryResults = $state<LibrarySearchJsonResult[]>([]);
+	let snippets = $state<SnippetJson[]>([]);
+	let totalTokens = $state(0);
+
+	let loadingLibraries = $state(false);
+	let loadingSnippets = $state(false);
+	let libraryError = $state<string | null>(null);
+	let snippetError = $state<string | null>(null);
+	let copyLabel = $state('Copy as Markdown');
+
+	// ---------------------------------------------------------------------------
+	// Derived
+	// ---------------------------------------------------------------------------
+
+	const hasLibraryResults = $derived(libraryResults.length > 0);
+	const hasSnippets = $derived(snippets.length > 0);
+	const step = $derived<'library' | 'docs'>(selectedLibraryId ? 'docs' : 'library');
+
+	// ---------------------------------------------------------------------------
+	// Initialise from URL params on mount
+	// ---------------------------------------------------------------------------
+
+	onMount(() => {
+		const currentPage = get(page);
+		const libParam = currentPage.url.searchParams.get('lib');
+		const qParam = currentPage.url.searchParams.get('q');
+
+		if (libParam) {
+			selectedLibraryId = libParam;
+			// Try to restore library name from id for display.
+			selectedLibraryTitle = libParam;
+		}
+		if (qParam) {
+			query = qParam;
+		}
+		if (libParam && qParam) {
+			searchDocs();
+		}
+	});
+
+	// ---------------------------------------------------------------------------
+	// Actions
+	// ---------------------------------------------------------------------------
+
+	async function searchLibraries() {
+		if (!libraryName.trim()) return;
+		loadingLibraries = true;
+		libraryError = null;
+		libraryResults = [];
+
+		try {
+			const res = await fetch(
+				`/api/v1/libs/search?libraryName=${encodeURIComponent(libraryName)}&query=${encodeURIComponent(query)}`
+			);
+			if (!res.ok) {
+				const data = await res.json();
+				throw new Error(data.error ?? `Request failed (${res.status})`);
+			}
+			const data = await res.json();
+			libraryResults = data.results ?? [];
+		} catch (e) {
+			libraryError = (e as Error).message;
+		} finally {
+			loadingLibraries = false;
+		}
+	}
+
+	async function searchDocs() {
+		if (!selectedLibraryId || !query.trim()) return;
+		loadingSnippets = true;
+		snippetError = null;
+		snippets = [];
+		totalTokens = 0;
+
+		try {
+			const url = new URL('/api/v1/context', window.location.origin);
+			url.searchParams.set('libraryId', selectedLibraryId);
+			url.searchParams.set('query', query);
+			const res = await fetch(url);
+			if (!res.ok) {
+				const data = await res.json();
+				throw new Error(data.error ?? `Request failed (${res.status})`);
+			}
+			const data = await res.json();
+			snippets = data.snippets ?? [];
+			totalTokens = data.totalTokens ?? 0;
+
+			// Sync URL state.
+			goto(
+				`/search?lib=${encodeURIComponent(selectedLibraryId)}&q=${encodeURIComponent(query)}`,
+				{ replaceState: true, keepFocus: true }
+			);
+		} catch (e) {
+			snippetError = (e as Error).message;
+		} finally {
+			loadingSnippets = false;
+		}
+	}
+
+	function selectLibrary(id: string) {
+		const found = libraryResults.find((r) => r.id === id);
+		selectedLibraryId = id;
+		selectedLibraryTitle = found?.title ?? id;
+		libraryResults = [];
+		libraryName = '';
+	}
+
+	function changeLibrary() {
+		selectedLibraryId = null;
+		selectedLibraryTitle = null;
+		snippets = [];
+		totalTokens = 0;
+		snippetError = null;
+		query = '';
+		// Reset URL.
+		goto('/search', { replaceState: true, keepFocus: true });
+	}
+
+	// ---------------------------------------------------------------------------
+	// Copy as Markdown
+	// ---------------------------------------------------------------------------
+
+	function buildMarkdown(): string {
+		const parts: string[] = [];
+
+		for (const snippet of snippets) {
+			if (snippet.type === 'code') {
+				const lang = snippet.codeList[0]?.language ?? '';
+				const code = snippet.codeList[0]?.code ?? '';
+				if (snippet.title) parts.push(`### ${snippet.title}`);
+				if (snippet.description) parts.push(`*${snippet.description}*`);
+				parts.push(`\`\`\`${lang}\n${code}\n\`\`\``);
+			} else {
+				if (snippet.breadcrumb) parts.push(`*${snippet.breadcrumb}*`);
+				parts.push(snippet.text);
+			}
+			parts.push('---');
+		}
+
+		if (parts.at(-1) === '---') parts.pop();
+		return parts.join('\n\n');
+	}
+
+	async function handleCopy() {
+		const markdown = buildMarkdown();
+		const ok = await copyToClipboard(markdown);
+		copyLabel = ok ? 'Copied!' : 'Failed to copy';
+		setTimeout(() => {
+			copyLabel = 'Copy as Markdown';
+		}, 2000);
+	}
+</script>
+
+<svelte:head>
+	<title>Search — TrueRef</title>
+</svelte:head>
+
+<div class="space-y-6">
+	<div>
+		<h1 class="text-xl font-semibold text-gray-900">Search Documentation</h1>
+		<p class="mt-0.5 text-sm text-gray-500">
+			Find libraries and query their indexed documentation.
+		</p>
+	</div>
+
+	{#if step === 'library'}
+		<!-- ------------------------------------------------------------------ -->
+		<!-- Step 1: Library search                                              -->
+		<!-- ------------------------------------------------------------------ -->
+		<div class="rounded-xl border border-gray-200 bg-white p-6 shadow-sm">
+			<h2 class="mb-1 text-sm font-semibold text-gray-700">Step 1 — Select a library</h2>
+			<p class="mb-4 text-xs text-gray-500">
+				Enter a library name to find matching indexed repositories.
+			</p>
+
+			<SearchInput
+				bind:value={libraryName}
+				placeholder="Library name, e.g. react, tailwind..."
+				onsubmit={searchLibraries}
+				loading={loadingLibraries}
+			/>
+		</div>
+
+		{#if libraryError}
+			<div class="rounded-lg bg-red-50 px-4 py-3">
+				<p class="text-sm text-red-700">{libraryError}</p>
+			</div>
+		{/if}
+
+		{#if loadingLibraries}
+			<div class="flex items-center justify-center py-12 text-sm text-gray-400">
+				Searching libraries...
+			</div>
+		{:else if hasLibraryResults}
+			<div class="space-y-3">
+				{#each libraryResults as result (result.id)}
+					<LibraryResult {result} onSelect={selectLibrary} />
+				{/each}
+			</div>
+		{:else if libraryName && !loadingLibraries && libraryResults.length === 0 && !libraryError}
+			<!-- Only show empty state after a search was executed -->
+		{/if}
+	{:else}
+		<!-- ------------------------------------------------------------------ -->
+		<!-- Step 2: Documentation query                                         -->
+		<!-- ------------------------------------------------------------------ -->
+		<div class="rounded-xl border border-gray-200 bg-white p-6 shadow-sm">
+			<div class="mb-4 flex items-center gap-3">
+				<div class="flex min-w-0 flex-1 items-center gap-2">
+					<span class="shrink-0 rounded bg-green-100 px-2 py-0.5 text-xs font-medium text-green-700">
+						Selected
+					</span>
+					<span class="truncate font-mono text-sm text-gray-700">{selectedLibraryTitle}</span>
+				</div>
+				<button
+					onclick={changeLibrary}
+					class="shrink-0 rounded-lg border border-gray-200 px-3 py-1.5 text-xs text-gray-600 transition-colors hover:bg-gray-50"
+				>
+					Change
+				</button>
+			</div>
+
+			<h2 class="mb-1 text-sm font-semibold text-gray-700">Step 2 — Query documentation</h2>
+			<p class="mb-4 text-xs text-gray-500">Ask a question about this library.</p>
+
+			<SearchInput
+				bind:value={query}
+				placeholder="What would you like to know?"
+				onsubmit={searchDocs}
+				loading={loadingSnippets}
+			/>
+		</div>
+
+		{#if snippetError}
+			<div class="rounded-lg bg-red-50 px-4 py-3">
+				<p class="text-sm text-red-700">{snippetError}</p>
+			</div>
+		{/if}
+
+		{#if loadingSnippets}
+			<div class="flex items-center justify-center py-12 text-sm text-gray-400">
+				Fetching documentation snippets...
+			</div>
+		{:else if hasSnippets}
+			<!-- Summary bar -->
+			<div class="flex items-center justify-between">
+				<p class="text-sm text-gray-500">
+					{snippets.length} snippet{snippets.length === 1 ? '' : 's'} &middot;
+					<span class="font-medium text-gray-700">{totalTokens.toLocaleString()} tokens</span>
+				</p>
+				<button
+					onclick={handleCopy}
+					class="rounded-lg border border-gray-200 px-3 py-1.5 text-xs text-gray-600 transition-colors hover:bg-gray-50"
+				>
+					{copyLabel}
+				</button>
+			</div>
+
+			<!-- Snippet list -->
+			<div class="space-y-4">
+				{#each snippets as snippet, i (i)}
+					<SnippetCard {snippet} />
+				{/each}
+			</div>
+		{:else if query && !loadingSnippets && snippets.length === 0 && !snippetError}
+			<div class="flex flex-col items-center py-16 text-center">
+				<p class="text-sm text-gray-500">No snippets found for that query.</p>
+				<p class="mt-1 text-xs text-gray-400">Try a different question or select another library.</p>
+			</div>
+		{/if}
+	{/if}
+</div>

src/routes/search/+page.ts

@@ -0,0 +1 @@
+export const ssr = false;