feat(ui): wire panelMode state with read/edit view switching

Adds TranscriptionPanelHeader and TranscriptionReadView to the
document detail page. Default mode is 'read' when blocks exist,
'edit' otherwise. Annotations dimmed in read mode.

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

frontend/src/lib/components/DocumentViewer.svelte

@@ -20,6 +20,7 @@ type Props = {
 	blockNumbers?: Record<string, number>;
 	annotationReloadKey?: number;
 	activeAnnotationId: string | null;
+	annotationsDimmed?: boolean;
 	onAnnotationClick: (id: string) => void;
 	onTranscriptionDraw?: (rect: DrawRect) => void;
 };
@@ -33,6 +34,7 @@ let {
 	blockNumbers = {},
 	annotationReloadKey = 0,
 	activeAnnotationId = $bindable(),
+	annotationsDimmed = false,
 	onAnnotationClick,
 	onTranscriptionDraw
 }: Props = $props();
@@ -90,6 +92,7 @@ let {
 			blockNumbers={blockNumbers}
 			annotationReloadKey={annotationReloadKey}
 			bind:activeAnnotationId={activeAnnotationId}
+			annotationsDimmed={annotationsDimmed}
 			onAnnotationClick={onAnnotationClick}
 			onTranscriptionDraw={onTranscriptionDraw}
 			documentFileHash={doc.fileHash ?? null}

frontend/src/lib/components/PdfViewer.svelte

@@ -16,7 +16,8 @@ let {
 	activeAnnotationId = $bindable<string | null>(null),
 	onAnnotationClick,
 	onTranscriptionDraw,
-	documentFileHash
+	documentFileHash,
+	annotationsDimmed = false
 }: {
 	url: string;
 	documentId?: string;
@@ -27,6 +28,7 @@ let {
 	onAnnotationClick?: (id: string) => void;
 	onTranscriptionDraw?: (rect: DrawRect) => void;
 	documentFileHash?: string | null;
+	annotationsDimmed?: boolean;
 } = $props();
 
 let pdfDoc = $state<PDFDocumentProxy | null>(null);
@@ -456,6 +458,7 @@ function zoomOut() {
 								color={TRANSCRIPTION_COLOR}
 								blockNumbers={blockNumbers}
 								activeAnnotationId={activeAnnotationId}
+								dimmed={annotationsDimmed}
 								onDraw={handleDraw}
 								onAnnotationClick={handleAnnotationClick}
 							/>

frontend/src/routes/documents/[id]/+page.svelte

@@ -3,6 +3,8 @@ import { onMount } from 'svelte';
 import DocumentTopBar from '$lib/components/DocumentTopBar.svelte';
 import DocumentViewer from '$lib/components/DocumentViewer.svelte';
 import TranscriptionEditView from '$lib/components/TranscriptionEditView.svelte';
+import TranscriptionReadView from '$lib/components/TranscriptionReadView.svelte';
+import TranscriptionPanelHeader from '$lib/components/TranscriptionPanelHeader.svelte';
 import type { TranscriptionBlockData } from '$lib/types';
 
 let { data } = $props();
@@ -49,7 +51,9 @@ async function loadFile(id: string) {
 // ── Mode state ───────────────────────────────────────────────────────────────
 
 let transcribeMode = $state(false);
+let panelMode = $state<'read' | 'edit'>('read');
 let activeAnnotationId = $state<string | null>(null);
+let highlightBlockId = $state<string | null>(null);
 
 // ── Transcription blocks ─────────────────────────────────────────────────────
 
@@ -64,6 +68,17 @@ const blockNumbers = $derived(
 	)
 );
 
+const hasBlocks = $derived(transcriptionBlocks.length > 0);
+
+const lastEditedAt = $derived.by(() => {
+	if (transcriptionBlocks.length === 0) return null;
+	const dates = transcriptionBlocks
+		.filter((b) => b.updatedAt)
+		.map((b) => new Date(b.updatedAt!).getTime());
+	if (dates.length === 0) return null;
+	return new Date(Math.max(...dates)).toISOString();
+});
+
 async function loadTranscriptionBlocks() {
 	if (!doc?.id) return;
 	try {
@@ -142,9 +157,17 @@ async function handleAnnotationClick(annotationId: string) {
 		await loadTranscriptionBlocks();
 	}
 
-	// Wait for DOM to render the blocks, then scroll to the matching one
+	// In read mode, highlight the matching paragraph
+	const block = transcriptionBlocks.find((b) => b.annotationId === annotationId);
+	if (block) {
+		highlightBlockId = block.id;
+		setTimeout(() => {
+			highlightBlockId = null;
+		}, 1500);
+	}
+
+	// Wait for DOM to render, then scroll to the matching block
 	requestAnimationFrame(() => {
-		const block = transcriptionBlocks.find((b) => b.annotationId === annotationId);
 		if (block) {
 			const el = document.querySelector(`[data-block-id="${block.id}"]`);
 			el?.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
@@ -152,10 +175,16 @@ async function handleAnnotationClick(annotationId: string) {
 	});
 }
 
-// Load blocks when transcribe mode is entered
+function handleParagraphClick(annotationId: string) {
+	activeAnnotationId = annotationId;
+}
+
+// Load blocks when transcribe mode is entered and set default panel mode
 $effect(() => {
 	if (transcribeMode) {
-		loadTranscriptionBlocks();
+		loadTranscriptionBlocks().then(() => {
+			panelMode = transcriptionBlocks.length > 0 ? 'read' : 'edit';
+		});
 	}
 });
 
@@ -211,6 +240,7 @@ onMount(() => {
 				transcribeMode={transcribeMode}
 				blockNumbers={blockNumbers}
 				annotationReloadKey={annotationReloadKey}
+				annotationsDimmed={transcribeMode && panelMode === 'read'}
 				bind:activeAnnotationId={activeAnnotationId}
 				onAnnotationClick={handleAnnotationClick}
 				onTranscriptionDraw={createBlockFromDraw}
@@ -219,18 +249,36 @@ onMount(() => {
 
 		{#if transcribeMode}
 			<div
-				class="shrink-0 border-t border-line md:w-[400px] md:border-t-0 md:border-l lg:w-[480px]"
+				class="flex shrink-0 flex-col border-t border-line md:w-[400px] md:border-t-0 md:border-l lg:w-[480px]"
 			>
-				<TranscriptionEditView
-					documentId={doc.id}
-					blocks={transcriptionBlocks}
-					canComment={canWrite}
-					currentUserId={currentUserId}
-					activeAnnotationId={activeAnnotationId}
-					onBlockFocus={handleBlockFocus}
-					onSaveBlock={saveBlock}
-					onDeleteBlock={deleteBlock}
+				<TranscriptionPanelHeader
+					mode={panelMode}
+					hasBlocks={hasBlocks}
+					blockCount={transcriptionBlocks.length}
+					lastEditedAt={lastEditedAt}
+					onModeChange={(m) => (panelMode = m)}
+					onClose={() => (transcribeMode = false)}
 				/>
+				<div class="flex-1 overflow-y-auto">
+					{#if panelMode === 'read'}
+						<TranscriptionReadView
+							blocks={transcriptionBlocks}
+							highlightBlockId={highlightBlockId}
+							onParagraphClick={handleParagraphClick}
+						/>
+					{:else}
+						<TranscriptionEditView
+							documentId={doc.id}
+							blocks={transcriptionBlocks}
+							canComment={canWrite}
+							currentUserId={currentUserId}
+							activeAnnotationId={activeAnnotationId}
+							onBlockFocus={handleBlockFocus}
+							onSaveBlock={saveBlock}
+							onDeleteBlock={deleteBlock}
+						/>
+					{/if}
+				</div>
 			</div>
 		{/if}
 	</div>