feat(new-doc): pre-fill date, sender and title from parsed filename

When a file is selected on the new document page, parseFilename runs
on the filename and suggests date, sender name and title via the new
suggestedDateIso / suggestedSenderName / suggestedTitle props. Each
suggestion is applied only while the respective field is still clean
(not dirty), so manual input is never overwritten.

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

frontend/src/lib/components/PersonTypeahead.svelte

@@ -9,6 +9,7 @@ interface Props {
 	label: string;
 	value?: string;
 	initialName?: string;
+	suggestedName?: string;
 	restrictToCorrespondentsOf?: string;
 	onchange?: (value: string) => void;
 }
@@ -18,12 +19,20 @@ let {
 	label,
 	value = $bindable(''),
 	initialName = '',
+	suggestedName = '',
 	restrictToCorrespondentsOf,
 	onchange
 }: Props = $props();
 
 let searchTerm = $state(initialName);
 
+$effect(() => {
+	const suggested = suggestedName;
+	if (suggested && !untrack(() => value)) {
+		searchTerm = suggested;
+	}
+});
+
 let results: Person[] = $state([]);
 let showDropdown = $state(false);
 let loading = $state(false);

frontend/src/lib/components/document/DescriptionSection.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+import { untrack } from 'svelte';
 import TagInput from '$lib/components/TagInput.svelte';
 import { m } from '$lib/paraglide/messages.js';
 
@@ -7,14 +8,26 @@ let {
 	initialTitle = '',
 	initialDocumentLocation = '',
 	initialSummary = '',
-	titleRequired = false
+	titleRequired = false,
+	suggestedTitle = ''
 }: {
 	tags?: string[];
 	initialTitle?: string;
 	initialDocumentLocation?: string;
 	initialSummary?: string;
 	titleRequired?: boolean;
+	suggestedTitle?: string;
 } = $props();
+
+let titleValue = $state(untrack(() => initialTitle));
+let titleDirty = $state(false);
+
+$effect(() => {
+	const suggested = suggestedTitle;
+	if (suggested && !untrack(() => titleDirty)) {
+		titleValue = suggested;
+	}
+});
 </script>
 
 <div class="rounded-sm border border-line bg-surface p-6 shadow-sm">
@@ -33,7 +46,11 @@ let {
 				id="title"
 				type="text"
 				name="title"
-				value={initialTitle}
+				value={titleValue}
+				oninput={(e) => {
+					titleValue = (e.target as HTMLInputElement).value;
+					titleDirty = true;
+				}}
 				required={titleRequired}
 				class="block w-full rounded border border-line p-2 text-sm shadow-sm focus:border-ink focus:ring-ink"
 			/>

frontend/src/lib/components/document/WhoWhenSection.svelte

@@ -16,13 +16,17 @@ let {
 	selectedReceivers = $bindable<Person[]>([]),
 	initialDateIso = '',
 	initialLocation = '',
-	initialSenderName = ''
+	initialSenderName = '',
+	suggestedDateIso = '',
+	suggestedSenderName = ''
 }: {
 	senderId?: string;
 	selectedReceivers?: Person[];
 	initialDateIso?: string;
 	initialLocation?: string;
 	initialSenderName?: string;
+	suggestedDateIso?: string;
+	suggestedSenderName?: string;
 } = $props();
 
 let dateDisplay = $state(untrack(() => isoToGerman(initialDateIso)));
@@ -37,6 +41,14 @@ function handleDateInput(e: Event) {
 	dateIso = result.iso;
 	dateDirty = true;
 }
+
+$effect(() => {
+	const suggested = suggestedDateIso;
+	if (suggested && !untrack(() => dateDirty)) {
+		dateDisplay = isoToGerman(suggested);
+		dateIso = suggested;
+	}
+});
 </script>
 
 <div class="rounded-sm border border-line bg-surface p-6 shadow-sm">
@@ -90,6 +102,7 @@ function handleDateInput(e: Event) {
 				label={m.form_label_sender()}
 				bind:value={senderId}
 				initialName={initialSenderName}
+				suggestedName={suggestedSenderName}
 			/>
 		</div>
 

frontend/src/routes/documents/new/+page.svelte

@@ -6,6 +6,7 @@ import WhoWhenSection from '$lib/components/document/WhoWhenSection.svelte';
 import DescriptionSection from '$lib/components/document/DescriptionSection.svelte';
 import TranscriptionSection from '$lib/components/document/TranscriptionSection.svelte';
 import FileSectionNew from './FileSectionNew.svelte';
+import { type FilenameParseResult } from '$lib/utils/filename';
 
 let { data, form } = $props();
 
@@ -14,6 +15,8 @@ let senderId = $state(untrack(() => data.initialSenderId));
 let selectedReceivers: { id: string; firstName: string; lastName: string }[] = $state(
 	untrack(() => data.initialReceivers)
 );
+
+let parsedSuggestion = $state<FilenameParseResult>({});
 </script>
 
 <div class="mx-auto max-w-4xl px-4 py-8">
@@ -50,10 +53,16 @@ let selectedReceivers: { id: string; firstName: string; lastName: string }[] = $
 			bind:senderId={senderId}
 			bind:selectedReceivers={selectedReceivers}
 			initialSenderName={data.initialSenderName}
+			suggestedDateIso={parsedSuggestion.dateIso ?? ''}
+			suggestedSenderName={parsedSuggestion.personName ?? ''}
+		/>
+		<DescriptionSection
+			bind:tags={tags}
+			titleRequired={true}
+			suggestedTitle={parsedSuggestion.suggestedTitle ?? ''}
 		/>
-		<DescriptionSection bind:tags={tags} titleRequired={true} />
 		<TranscriptionSection />
-		<FileSectionNew />
+		<FileSectionNew onfileParsed={(r) => (parsedSuggestion = r)} />
 
 		<!-- Sticky Save Bar -->
 		<div

frontend/src/routes/documents/new/FileSectionNew.svelte

@@ -1,5 +1,17 @@
 <script lang="ts">
 import { m } from '$lib/paraglide/messages.js';
+import { parseFilename, type FilenameParseResult } from '$lib/utils/filename';
+
+let {
+	onfileParsed
+}: {
+	onfileParsed?: (result: FilenameParseResult) => void;
+} = $props();
+
+function handleFileChange(e: Event) {
+	const file = (e.target as HTMLInputElement).files?.[0];
+	if (file) onfileParsed?.(parseFilename(file.name));
+}
 </script>
 
 <div class="rounded-sm border border-line bg-surface p-6 shadow-sm">
@@ -15,6 +27,7 @@ import { m } from '$lib/paraglide/messages.js';
 		id="file-upload"
 		type="file"
 		name="file"
+		onchange={handleFileChange}
 		class="block w-full cursor-pointer text-sm
                text-ink-2 file:mr-4 file:rounded
                file:border-0 file:bg-muted