feat(timeline): add a WRITE_ALL-gated edit pencil to WorldBand

A curated HISTORICAL band had no edit affordance at all. Mirror the
EventPill pencil inline at the end of the band (data-testid="event-edit",
/edit href, aria-hidden glyph + sr-only Bearbeiten), gated on
canWrite && eventId != null. Thread canWrite to WorldBand through both
the year-band path and the undated bucket.

Refs #842
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/timeline/TimelineView.svelte

@@ -79,7 +79,7 @@ const isEmpty = $derived(timeline.years.length === 0 && timeline.undated.length
 					<li>
 						{#if entry.kind === 'EVENT'}
 							{#if entry.type === 'HISTORICAL'}
-								<WorldBand entry={entry} />
+								<WorldBand entry={entry} canWrite={canWrite} />
 							{:else}
 								<EventPill entry={entry} canWrite={canWrite} />
 							{/if}

frontend/src/lib/timeline/TimelineView.svelte.spec.ts

@@ -312,4 +312,33 @@ describe('TimelineView', () => {
 		render(TimelineView, { canWrite: false, timeline: bothPaths() });
 		expect(document.querySelectorAll('[data-testid="event-edit"]')).toHaveLength(0);
 	});
+
+	it('threads canWrite to a curated HISTORICAL world band in both paths (REQ-006/009)', () => {
+		const world = (eventId: string, title: string) =>
+			makeEntry({
+				kind: 'EVENT',
+				type: 'HISTORICAL',
+				derived: false,
+				eventId,
+				precision: 'YEAR',
+				eventDate: '1929-01-01',
+				eventDateEnd: undefined,
+				title,
+				senderName: '',
+				receiverName: '',
+				documentId: undefined
+			});
+		render(TimelineView, {
+			canWrite: true,
+			timeline: makeTimelineDTO({
+				years: [makeYear(1929, [world('wb', 'Weltwirtschaftskrise')])],
+				undated: [world('wu', 'Unbekanntes Weltereignis')]
+			})
+		});
+		const hrefs = Array.from(document.querySelectorAll('[data-testid="event-edit"]')).map((a) =>
+			a.getAttribute('href')
+		);
+		expect(hrefs).toContain('/zeitstrahl/events/wb/edit');
+		expect(hrefs).toContain('/zeitstrahl/events/wu/edit');
+	});
 });

frontend/src/lib/timeline/WorldBand.svelte

@@ -11,9 +11,11 @@ type TimelineEntryDTO = components['schemas']['TimelineEntryDTO'];
  * (REQ-009). A RANGE carries a visible span pill ("1914–1918") with a Zeitraum
  * aria-label; a RANGE with no end degrades to the start year, no pill (REQ-010).
  * The glyph is a redundant non-color cue with an sr-only label (REQ-018); text
- * uses text-ink-2 to stay AA in both themes (REQ-019).
+ * uses text-ink-2 to stay AA in both themes (REQ-019). A curator (`canWrite`,
+ * gate-closed by default) gets an inline edit pencil for a curated event with an
+ * eventId — #842 REQ-006/007/008; UX gate only, the #781 route guard is the boundary.
  */
-let { entry }: { entry: TimelineEntryDTO } = $props();
+let { entry, canWrite = false }: { entry: TimelineEntryDTO; canWrite?: boolean } = $props();
 
 const config = $derived(getAccentConfig(entry));
 const dateLabel = $derived(timelineDateLabel(entry.eventDate, entry.precision, entry.eventDateEnd));
@@ -24,6 +26,9 @@ const dateText = $derived(showSpan ? null : entry.precision === 'RANGE' ? fromYe
 // Every WorldBand is a HISTORICAL band, so the visible "historisch" register
 // always trails the subtitle as plain text — never a second pill (REQ-009).
 const historical = $derived(m.timeline_layer_historical_suffix());
+// A HISTORICAL event is never derived, so the edit gate is just the curator
+// flag plus a real eventId (#842 REQ-006/008).
+const canEdit = $derived(canWrite && entry.eventId != null);
 </script>
 
 <div class="my-3 border-y border-line bg-canvas px-4 py-2 text-center">
@@ -46,4 +51,14 @@ const historical = $derived(m.timeline_layer_historical_suffix());
 	<!-- Single trailing "· historisch" register, after the title and any
 	     span pill / date — one render site, consistent separator (REQ-009). -->
 	<span class="ml-2 font-sans text-xs text-ink-3">· {historical}</span>
+	{#if canEdit}
+		<a
+			data-testid="event-edit"
+			href="/zeitstrahl/events/{entry.eventId}/edit"
+			class="ml-2 rounded-sm px-1 font-sans text-xs text-ink-3 hover:text-brand-navy focus:outline-none focus-visible:ring-2 focus-visible:ring-brand-navy"
+		>
+			<span aria-hidden="true">✎</span>
+			<span class="sr-only">{m.btn_edit()}</span>
+		</a>
+	{/if}
 </div>

frontend/src/lib/timeline/WorldBand.svelte.spec.ts

@@ -73,4 +73,35 @@ describe('WorldBand', () => {
 		expect(pill?.textContent).not.toContain(m.timeline_layer_historical_suffix());
 		expect(document.body.textContent).toContain(m.timeline_layer_historical_suffix());
 	});
+
+	const HIST_EVENT_ID = '44444444-4444-4444-4444-444444444444';
+
+	it('shows an edit affordance for a curated HISTORICAL event when canWrite is true (REQ-006)', () => {
+		render(WorldBand, { canWrite: true, entry: historical({ eventId: HIST_EVENT_ID }) });
+		const edit = document.querySelector('[data-testid="event-edit"]') as HTMLAnchorElement | null;
+		expect(edit).not.toBeNull();
+		expect(edit?.getAttribute('href')).toBe(`/zeitstrahl/events/${HIST_EVENT_ID}/edit`);
+	});
+
+	it('mirrors the EventPill pencil: aria-hidden ✎ glyph + sr-only Bearbeiten label (REQ-006)', () => {
+		render(WorldBand, { canWrite: true, entry: historical({ eventId: HIST_EVENT_ID }) });
+		const edit = document.querySelector('[data-testid="event-edit"]');
+		expect(edit?.querySelector('[aria-hidden="true"]')?.textContent).toBe('✎');
+		expect(edit?.querySelector('.sr-only')?.textContent).toBe(m.btn_edit());
+	});
+
+	it('renders no edit affordance for a curated HISTORICAL event when canWrite is false (REQ-007)', () => {
+		render(WorldBand, { canWrite: false, entry: historical({ eventId: HIST_EVENT_ID }) });
+		expect(document.querySelector('[data-testid="event-edit"]')).toBeNull();
+	});
+
+	it('renders no edit affordance when the canWrite prop is omitted (gate-closed default) (REQ-007)', () => {
+		render(WorldBand, { entry: historical({ eventId: HIST_EVENT_ID }) });
+		expect(document.querySelector('[data-testid="event-edit"]')).toBeNull();
+	});
+
+	it('shows no edit affordance when eventId is null even with canWrite (REQ-008)', () => {
+		render(WorldBand, { canWrite: true, entry: historical({ eventId: undefined }) });
+		expect(document.querySelector('[data-testid="event-edit"]')).toBeNull();
+	});
 });

frontend/src/lib/timeline/YearBand.svelte

@@ -59,7 +59,7 @@ const rows = $derived.by<Row[]>(() => {
 		{#each rows as row (row.t === 'strip' ? `strip-${year.year}` : entryKey(row.entry))}
 			{#if row.t === 'event'}
 				{#if row.entry.type === 'HISTORICAL'}
-					<WorldBand entry={row.entry} />
+					<WorldBand entry={row.entry} canWrite={canWrite} />
 				{:else}
 					<EventPill entry={row.entry} canWrite={canWrite} />
 				{/if}