fix(frontend): show error on training start failure, add aria-live and dismiss to success message

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

frontend/messages/de.json

@@ -330,6 +330,7 @@
 	"comment_time_days": "vor {count} Tag(en)",
 	"comment_panel_title": "Kommentare",
 	"comment_panel_close": "Schließen",
+	"comp_dismiss": "Schließen",
 	"doc_panel_tab_metadata": "Metadaten",
 	"doc_panel_tab_transcription": "Transkription",
 	"doc_panel_tab_discussion": "Diskussion",
@@ -541,6 +542,7 @@
 	"training_start_btn": "Training starten",
 	"training_in_progress": "…",
 	"training_success": "Training wurde gestartet und abgeschlossen.",
+	"training_start_failed": "Training konnte nicht gestartet werden. Bitte versuche es erneut.",
 	"training_too_few_blocks": "Mindestens 5 geprüfte Blöcke erforderlich (aktuell: {available}).",
 	"training_service_down": "OCR-Dienst ist nicht erreichbar.",
 	"training_history_heading": "Verlauf",

frontend/messages/en.json

@@ -330,6 +330,7 @@
 	"comment_time_days": "{count} day(s) ago",
 	"comment_panel_title": "Comments",
 	"comment_panel_close": "Close",
+	"comp_dismiss": "Dismiss",
 	"doc_panel_tab_metadata": "Metadata",
 	"doc_panel_tab_transcription": "Transcription",
 	"doc_panel_tab_discussion": "Discussion",
@@ -541,6 +542,7 @@
 	"training_start_btn": "Start training",
 	"training_in_progress": "…",
 	"training_success": "Training started and completed.",
+	"training_start_failed": "Failed to start training. Please try again.",
 	"training_too_few_blocks": "At least 5 reviewed blocks required (currently: {available}).",
 	"training_service_down": "OCR service is unavailable.",
 	"training_history_heading": "History",

frontend/messages/es.json

@@ -330,6 +330,7 @@
 	"comment_time_days": "hace {count} día(s)",
 	"comment_panel_title": "Comentarios",
 	"comment_panel_close": "Cerrar",
+	"comp_dismiss": "Cerrar",
 	"doc_panel_tab_metadata": "Metadatos",
 	"doc_panel_tab_transcription": "Transcripción",
 	"doc_panel_tab_discussion": "Discusión",
@@ -541,6 +542,7 @@
 	"training_start_btn": "Iniciar entrenamiento",
 	"training_in_progress": "…",
 	"training_success": "Entrenamiento iniciado y completado.",
+	"training_start_failed": "No se pudo iniciar el entrenamiento. Por favor, inténtalo de nuevo.",
 	"training_too_few_blocks": "Se requieren al menos 5 bloques revisados (actualmente: {available}).",
 	"training_service_down": "El servicio OCR no está disponible.",
 	"training_history_heading": "Historial",

frontend/src/lib/components/OcrTrainingCard.svelte

@@ -21,6 +21,7 @@ let { trainingInfo }: Props = $props();
 
 let training = $state(false);
 let successMessage = $state<string | null>(null);
+let errorMessage = $state<string | null>(null);
 
 const available = $derived(trainingInfo?.availableBlocks ?? 0);
 const tooFewBlocks = $derived(available < 5);
@@ -30,6 +31,7 @@ const disabled = $derived(training || tooFewBlocks || serviceDown);
 async function startTraining() {
 	training = true;
 	successMessage = null;
+	errorMessage = null;
 	try {
 		const res = await fetch('/api/ocr/train', { method: 'POST' });
 		if (res.ok) {
@@ -37,7 +39,11 @@ async function startTraining() {
 			setTimeout(() => {
 				successMessage = null;
 			}, 5000);
+		} else {
+			errorMessage = m.training_start_failed();
 		}
+	} catch {
+		errorMessage = m.training_start_failed();
 	} finally {
 		training = false;
 	}
@@ -72,7 +78,19 @@ async function startTraining() {
 	{/if}
 
 	{#if successMessage}
-		<p class="mt-2 text-xs text-green-700">{successMessage}</p>
+		<p class="mt-2 flex items-center gap-2 text-xs text-green-700" aria-live="polite">
+			{successMessage}
+			<button
+				type="button"
+				class="underline hover:no-underline"
+				onclick={() => (successMessage = null)}
+				aria-label={m.comp_dismiss()}>×</button
+			>
+		</p>
+	{/if}
+
+	{#if errorMessage}
+		<p class="mt-2 text-xs text-red-600" aria-live="assertive">{errorMessage}</p>
 	{/if}
 
 	<h3 class="mt-6 mb-3 text-xs font-bold tracking-widest text-ink-3 uppercase">