diff --git a/backend/src/main/java/org/raddatz/familienarchiv/controller/DocumentController.java b/backend/src/main/java/org/raddatz/familienarchiv/controller/DocumentController.java
index a7867c92..20717feb 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/controller/DocumentController.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/controller/DocumentController.java
@@ -3,6 +3,7 @@ package org.raddatz.familienarchiv.controller;
 import java.io.IOException;
 import java.time.LocalDate;
 import java.util.ArrayList;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -272,7 +273,7 @@ public class DocumentController {
         // Dedupe duplicate document IDs while preserving submission order. A
         // double-click on "Alle X editieren" would otherwise hit each document
         // twice and inflate the `updated` count returned to the user.
-        java.util.LinkedHashSet<UUID> uniqueIds = new java.util.LinkedHashSet<>(dto.getDocumentIds());
+        LinkedHashSet<UUID> uniqueIds = new LinkedHashSet<>(dto.getDocumentIds());
 
         for (UUID id : uniqueIds) {
             try {
@@ -324,7 +325,7 @@ public class DocumentController {
 
     @PostMapping(value = "/batch-metadata", consumes = MediaType.APPLICATION_JSON_VALUE)
     @RequirePermission(Permission.READ_ALL)
-    public List<DocumentBatchSummary> batchMetadata(@RequestBody BatchMetadataRequest request, Authentication authentication) {
+    public List<DocumentBatchSummary> batchMetadata(@RequestBody @Valid BatchMetadataRequest request, Authentication authentication) {
         if (request == null || request.ids() == null || request.ids().isEmpty()) {
             throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "ids is required");
         }
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/controller/DocumentControllerTest.java b/backend/src/test/java/org/raddatz/familienarchiv/controller/DocumentControllerTest.java
index 5d2ea90b..cbf2ece6 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/controller/DocumentControllerTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/controller/DocumentControllerTest.java
@@ -996,6 +996,24 @@ class DocumentControllerTest {
                 .andExpect(jsonPath("$.code").value("BULK_EDIT_TOO_MANY_IDS"));
     }
 
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchBulk_returns400_whenArchiveBoxExceeds255Chars() throws Exception {
+        // Tobias C2 — DocumentBulkEditDTO.archiveBox carries @Size(max=255).
+        // Without @Valid on @RequestBody this would silently land an
+        // arbitrarily long string; the test pins both the annotation and
+        // the controller-level @Valid wiring.
+        when(userService.findByEmail(any())).thenReturn(AppUser.builder().id(UUID.randomUUID()).build());
+        UUID id = UUID.randomUUID();
+        String tooLong = "x".repeat(256);
+
+        String body = "{\"documentIds\":[\"" + id + "\"],\"archiveBox\":\"" + tooLong + "\"}";
+        mockMvc.perform(patch("/api/documents/bulk")
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(body))
+                .andExpect(status().isBadRequest());
+    }
+
     @Test
     @WithMockUser(authorities = "WRITE_ALL")
     void patchBulk_acceptsExactly500Ids_atTheCap() throws Exception {
diff --git a/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte b/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte
index 3e062058..12ef0aa3 100644
--- a/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte
+++ b/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
 import { SvelteMap } from 'svelte/reactivity';
 import { goto } from '$app/navigation';
-import { onDestroy, untrack } from 'svelte';
+import { onDestroy, onMount, untrack } from 'svelte';
 import { m } from '$lib/paraglide/messages.js';
 import { getConfirmService } from '$lib/services/confirm.svelte.js';
 import type { ConfirmService } from '$lib/services/confirm.svelte.js';
@@ -73,8 +73,11 @@ let archiveFolder = $state('');
 
 // Hydrate edit-mode entries on mount. The IDs in bulkSelectionStore drive the
 // fetch upstream in the route — by the time this layout mounts, the metadata
-// has already been resolved into `initialEditEntries`.
-if (mode === 'edit') {
+// has already been resolved into `initialEditEntries`. Wrapped in onMount so
+// the SvelteMap mutation is unambiguously tied to instance lifecycle, not to
+// the script body's first execution (Felix C4 cycle 3).
+onMount(() => {
+	if (mode !== 'edit') return;
 	for (const entry of untrack(() => initialEditEntries)) {
 		files.set(entry.id, {
 			id: entry.id,
@@ -85,7 +88,7 @@ if (mode === 'edit') {
 		});
 		if (!activeId) activeId = entry.id;
 	}
-}
+});
 
 // --- Derived ---
 const isMulti = $derived(files.size >= 2);
diff --git a/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte.spec.ts b/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte.spec.ts
index 5fb57cac..adb0b525 100644
--- a/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte.spec.ts
+++ b/frontend/src/lib/components/document/BulkDocumentEditLayout.svelte.spec.ts
@@ -401,6 +401,24 @@ describe('BulkDocumentEditLayout — mode="edit"', () => {
 		expect(replaceBadges.length).toBeGreaterThanOrEqual(4);
 	});
 
+	it('topbar reads "Massenbearbeitung" + "{count} werden bearbeitet" in edit mode', async () => {
+		// Elicit C1 fix — upload-flavoured "Mehrere Dokumente hochladen" /
+		// "werden erstellt" copy must not appear when mode === 'edit'.
+		const { container } = render(BulkDocumentEditLayout, {
+			mode: 'edit',
+			initialEditEntries: [editEntry(1), editEntry(2)]
+		});
+		// Topbar title slot
+		const topbar = container.querySelector('span.font-bold.text-ink');
+		expect(topbar?.textContent).toContain('Massenbearbeitung');
+		// Count pill
+		const pill = container.querySelector('span.bg-accent');
+		expect(pill?.textContent).toContain('werden bearbeitet');
+		// Negative: must NOT show upload-flavoured copy
+		expect(topbar?.textContent ?? '').not.toContain('hochladen');
+		expect(pill?.textContent ?? '').not.toContain('werden erstellt');
+	});
+
 	it('shows the archiveBox and archiveFolder bulk-only inputs', async () => {
 		const { container } = render(BulkDocumentEditLayout, {
 			mode: 'edit',
diff --git a/frontend/src/lib/components/document/BulkSelectionBar.svelte.spec.ts b/frontend/src/lib/components/document/BulkSelectionBar.svelte.spec.ts
index da29ead3..523b797e 100644
--- a/frontend/src/lib/components/document/BulkSelectionBar.svelte.spec.ts
+++ b/frontend/src/lib/components/document/BulkSelectionBar.svelte.spec.ts
@@ -86,4 +86,37 @@ describe('BulkSelectionBar', () => {
 		// Nothing to clear, no error.
 		expect(bulkSelectionStore.size).toBe(0);
 	});
+
+	it('Escape does not clear when an open <dialog> is present (Leonie B6 scope guard)', async () => {
+		bulkSelectionStore.add('a');
+		bulkSelectionStore.add('b');
+		render(BulkSelectionBar, { canWrite: true });
+
+		// Simulate a ConfirmDialog being open in front of the bar.
+		const overlay = document.createElement('dialog');
+		overlay.setAttribute('open', '');
+		document.body.appendChild(overlay);
+		try {
+			window.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape' }));
+			// Escape is captured by the dialog, not the bar — selection survives.
+			expect(bulkSelectionStore.size).toBe(2);
+		} finally {
+			overlay.remove();
+		}
+	});
+
+	it('Escape does not clear when an aria-expanded popover is present', async () => {
+		bulkSelectionStore.add('a');
+		render(BulkSelectionBar, { canWrite: true });
+
+		const trigger = document.createElement('button');
+		trigger.setAttribute('aria-expanded', 'true');
+		document.body.appendChild(trigger);
+		try {
+			window.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape' }));
+			expect(bulkSelectionStore.size).toBe(1);
+		} finally {
+			trigger.remove();
+		}
+	});
 });
diff --git a/frontend/src/lib/components/document/DescriptionSection.svelte.spec.ts b/frontend/src/lib/components/document/DescriptionSection.svelte.spec.ts
new file mode 100644
index 00000000..8d000a8c
--- /dev/null
+++ b/frontend/src/lib/components/document/DescriptionSection.svelte.spec.ts
@@ -0,0 +1,50 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import DescriptionSection from './DescriptionSection.svelte';
+
+afterEach(() => cleanup());
+
+describe('DescriptionSection — onMount seeding (Felix B1/B2 fix regression fence)', () => {
+	it('pre-fills the title input from initialTitle when currentTitle is empty', async () => {
+		render(DescriptionSection, { initialTitle: 'Brief an Anna' });
+		const titleInput = document.querySelector('input#title') as HTMLInputElement;
+		expect(titleInput).not.toBeNull();
+		expect(titleInput.value).toBe('Brief an Anna');
+	});
+
+	it('does not stomp a parent-bound currentTitle that is already non-empty', async () => {
+		render(DescriptionSection, {
+			currentTitle: 'Parent Title',
+			initialTitle: 'Should Not Win'
+		});
+		const titleInput = document.querySelector('input#title') as HTMLInputElement;
+		expect(titleInput.value).toBe('Parent Title');
+	});
+
+	it('pre-fills the documentLocation input from initialDocumentLocation', async () => {
+		render(DescriptionSection, { initialDocumentLocation: 'Schrank 3, Mappe B' });
+		const locationInput = document.querySelector('input#documentLocation') as HTMLInputElement;
+		expect(locationInput.value).toBe('Schrank 3, Mappe B');
+	});
+
+	it('does not stomp a parent-bound documentLocation that is already non-empty', async () => {
+		render(DescriptionSection, {
+			documentLocation: 'Bound Value',
+			initialDocumentLocation: 'Should Not Win'
+		});
+		const locationInput = document.querySelector('input#documentLocation') as HTMLInputElement;
+		expect(locationInput.value).toBe('Bound Value');
+	});
+
+	it('renders the editMode-only archiveBox + archiveFolder fields when editMode=true', async () => {
+		render(DescriptionSection, { editMode: true, hideTitle: true });
+		expect(document.querySelector('[data-testid="description-archive-box"]')).not.toBeNull();
+		expect(document.querySelector('[data-testid="description-archive-folder"]')).not.toBeNull();
+	});
+
+	it('hides the editMode-only archive fields when editMode=false', async () => {
+		render(DescriptionSection, { editMode: false });
+		expect(document.querySelector('[data-testid="description-archive-box"]')).toBeNull();
+		expect(document.querySelector('[data-testid="description-archive-folder"]')).toBeNull();
+	});
+});
diff --git a/frontend/src/lib/components/document/WhoWhenSection.svelte.spec.ts b/frontend/src/lib/components/document/WhoWhenSection.svelte.spec.ts
new file mode 100644
index 00000000..a1b26628
--- /dev/null
+++ b/frontend/src/lib/components/document/WhoWhenSection.svelte.spec.ts
@@ -0,0 +1,42 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import WhoWhenSection from './WhoWhenSection.svelte';
+
+afterEach(() => cleanup());
+
+describe('WhoWhenSection — onMount seeding (Felix B1 fix regression fence)', () => {
+	it('pre-fills the date input from initialDateIso when the bindable is empty', async () => {
+		render(WhoWhenSection, { initialDateIso: '2024-03-15' });
+		// isoToGerman('2024-03-15') → '15.03.2024'
+		const dateInput = document.querySelector('input#documentDate') as HTMLInputElement;
+		expect(dateInput).not.toBeNull();
+		expect(dateInput.value).toBe('15.03.2024');
+	});
+
+	it('does not stomp a parent-bound dateIso that is already non-empty', async () => {
+		// dateIso bindable is '2026-01-01' from the parent; initialDateIso is the
+		// "fallback seed". onMount must not overwrite the already-bound value.
+		render(WhoWhenSection, { dateIso: '2026-01-01', initialDateIso: '1900-01-01' });
+		const dateInput = document.querySelector('input#documentDate') as HTMLInputElement;
+		expect(dateInput.value).toBe('01.01.2026');
+	});
+
+	it('hides the date field when hideDate=true (bulk-edit mode)', async () => {
+		render(WhoWhenSection, { hideDate: true });
+		await expect.element(page.getByTestId('who-when-date')).not.toBeInTheDocument();
+	});
+
+	it('renders the meta_location input only outside editMode', async () => {
+		const { rerender } = render(WhoWhenSection, { editMode: true });
+		expect(document.querySelector('input#location')).toBeNull();
+		await rerender({ editMode: false });
+		expect(document.querySelector('input#location')).not.toBeNull();
+	});
+
+	it('pre-fills the location input from initialLocation', async () => {
+		render(WhoWhenSection, { editMode: false, initialLocation: 'Berlin' });
+		const locationInput = document.querySelector('input#location') as HTMLInputElement;
+		expect(locationInput.value).toBe('Berlin');
+	});
+});
diff --git a/frontend/src/routes/+layout.svelte b/frontend/src/routes/+layout.svelte
index 9a121f7a..52340f28 100644
--- a/frontend/src/routes/+layout.svelte
+++ b/frontend/src/routes/+layout.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
 import './layout.css';
 import { page } from '$app/state';
-import { onMount } from 'svelte';
+import { onMount, untrack } from 'svelte';
 import * as m from '$lib/paraglide/messages.js';
 import LanguageSwitcher from '$lib/components/LanguageSwitcher.svelte';
 import ThemeToggle from '$lib/components/ThemeToggle.svelte';
@@ -22,6 +22,9 @@ provideConfirmService();
 // surface the BulkSelectionBar. Without this the selection silently follows
 // the user to /persons / /admin etc. and reappears as a stale 3-doc count
 // when they wander back to /documents — Felix C4 on PR #331.
+//
+// `bulkSelectionStore.size` is read inside `untrack` so the effect only
+// re-fires on route change, not on every checkbox toggle (Felix C3 cycle 3).
 $effect(() => {
 	const path = page.url.pathname;
 	const inBulkContext =
@@ -29,8 +32,10 @@ $effect(() => {
 		path.startsWith('/documents/') ||
 		path === '/enrich' ||
 		path.startsWith('/enrich/');
-	if (!inBulkContext && bulkSelectionStore.size > 0) {
-		bulkSelectionStore.clear();
+	if (!inBulkContext) {
+		untrack(() => {
+			if (bulkSelectionStore.size > 0) bulkSelectionStore.clear();
+		});
 	}
 });