fix: preserve hidden note title across editor modes

src/lib/components/Editor.svelte

@@ -54,6 +54,7 @@
 	import { convertListNode, type MixedListName } from '$lib/editor/mixedLists';
 	import { clearFormatting } from '$lib/editor/clearFormatting';
 	import { serializeInlineMarkdown } from '$lib/editor/markdown';
+	import { restoreTitleHeading, stripTitleHeading, type HiddenTitleHeading } from '$lib/editor/titleVisibility';
 	import { replaceWithWikiLink } from '$lib/editor/wikiLinks';
 	import { assetSourceToMarkdown, assetUrlToLocalPath, normalizeLocalAssetPath, resolveVaultFilePath } from '$lib/utils/paths';
 	import GraphView from './GraphView.svelte';
@@ -117,9 +118,7 @@
 	let hasPendingBlobs = false;
 	let lastSourceMode = $sourceMode;
 	let linkContextMenu = $state<{ x: number; y: number; href: string; anchor: HTMLAnchorElement } | null>(null);
-	let titleWasStripped = false;
-	let strippedTitle = '';
-	let strippedHeadingPrefix = '';
+	let hiddenTitleHeading: HiddenTitleHeading | null = null;
 	let taskRevealTimer: ReturnType<typeof setTimeout> | null = null;
 	let taskRevealElement: HTMLElement | null = null;
 	let taskRevealRequest = 0;
@@ -3403,44 +3402,13 @@
 	}
 
 	function stripTitleH1(md: string): string {
-		const title = $activeNote?.meta.title;
-		if (!$appConfig?.hide_title_in_body || !title) {
-			titleWasStripped = false;
-			strippedTitle = '';
-			strippedHeadingPrefix = '';
-			return md;
-		}
-		// Find the first non-empty line
-		const lines = md.split('\n');
-		for (let i = 0; i < lines.length; i++) {
-			const line = lines[i].trim();
-			if (line === '') continue;
-			// Check if it's a heading (any level) matching the note title
-			// Normalize: lowercase, collapse whitespace, strip common separators (- - _)
-			const normalize = (s: string) => s.trim().toLowerCase().replace(/[\s\-—_]+/g, ' ');
-			const match = line.match(/^(#{1,6})\s+(.+)$/);
-			if (match && normalize(match[2]) === normalize(title)) {
-				titleWasStripped = true;
-				strippedTitle = title.trim();
-				strippedHeadingPrefix = match[1]; // preserve original heading level (e.g. "##")
-				lines.splice(i, 1);
-				// Also remove a trailing blank line after the heading if present
-				if (i < lines.length && lines[i].trim() === '') {
-					lines.splice(i, 1);
-				}
-				return lines.join('\n');
-			}
-			break; // First non-empty line isn't a matching heading, stop
-		}
-		titleWasStripped = false;
-		strippedTitle = '';
-		strippedHeadingPrefix = '';
-		return md;
+		const result = stripTitleHeading(md, $activeNote?.meta.title, $appConfig?.hide_title_in_body ?? false);
+		hiddenTitleHeading = result.hiddenTitle;
+		return result.markdown;
 	}
 
 	function restoreTitleH1(md: string): string {
-		if (!titleWasStripped || !strippedTitle) return md;
-		return `${strippedHeadingPrefix} ${strippedTitle}\n\n${md}`;
+		return restoreTitleHeading(md, hiddenTitleHeading);
 	}
 
 	function editorToMarkdown(): string {
@@ -5794,7 +5762,7 @@
 				? editor.state.doc.textBetween(0, editor.state.selection.from, '\n', '').replace(/\s/g, '').length
 				: 0;
 			const docNonWs = docNonWhitespace();
-			sourceContent = editor ? editorToMarkdown() : ($activeNote?.content ?? '');
+			sourceContent = stripTitleH1(editor ? editorToMarkdown() : ($activeNote?.content ?? ''));
 			resetSourceHistory(sourceContent);
 			lastSourceMode = true;
 			const target = caretNonWs > 0 ? scanAlign(sourceContent, docNonWs, { stopAtNw: caretNonWs }).srcOffset : 0;
@@ -5821,20 +5789,20 @@
 			};
 			if (isMobile) {
 				// Mobile: editor stays in DOM, just update its content
-				const content = srcText || ($activeNote?.content ?? '');
+				const content = srcText;
 				if (editor) {
 					ignoreNextUpdate = true;
-					editor.commands.setContent(markdownToHtml(content));
+					editor.commands.setContent(markdownToHtml(restoreTitleH1(content)));
 					tick().then(restoreRichCaret);
 				}
 			} else {
 				// Desktop: destroy old editor (its DOM element is gone),
 				// wait for DOM to swap textarea→div, then create editor on new element.
 				destroyEditor();
-				const content = srcText || ($activeNote?.content ?? '');
+				const content = srcText;
 				tick().then(() => {
 					if (editorElement && !editor) {
-						createEditor(content);
+						createEditor(restoreTitleH1(content));
 						restoreRichCaret();
 					}
 				});
@@ -5967,7 +5935,7 @@
 							const oldPath = $activeNotePath;
 							$activeNote.meta.title = newTitle;
 							// Update stripped title so restoreTitleH1 uses the new title
-							if (titleWasStripped) strippedTitle = newTitle;
+							if (hiddenTitleHeading) hiddenTitleHeading = { ...hiddenTitleHeading, title: newTitle };
 							$editorDirty = true;
 							// Force save current editor content before renaming so disk is up-to-date
 							await forceSave();

src/lib/editor/titleVisibility.ts

@@ -0,0 +1,46 @@
+export type HiddenTitleHeading = {
+	headingPrefix: string;
+	title: string;
+};
+
+type TitleHeadingResult = {
+	markdown: string;
+	hiddenTitle: HiddenTitleHeading | null;
+};
+
+function normalizeTitle(value: string): string {
+	return value.trim().toLowerCase().replace(/[\s\-_\u2014]+/g, ' ');
+}
+
+export function stripTitleHeading(
+	markdown: string,
+	title: string | undefined,
+	hideTitle: boolean,
+): TitleHeadingResult {
+	if (!hideTitle || !title) return { markdown, hiddenTitle: null };
+
+	const lines = markdown.split('\n');
+	for (let i = 0; i < lines.length; i++) {
+		const line = lines[i].trim();
+		if (line === '') continue;
+
+		const match = line.match(/^(#{1,6})\s+(.+)$/);
+		if (match && normalizeTitle(match[2]) === normalizeTitle(title)) {
+			const hiddenTitle = { headingPrefix: match[1], title: title.trim() };
+			lines.splice(i, 1);
+			if (i < lines.length && lines[i].trim() === '') lines.splice(i, 1);
+			return { markdown: lines.join('\n'), hiddenTitle };
+		}
+		break;
+	}
+
+	return { markdown, hiddenTitle: null };
+}
+
+export function restoreTitleHeading(
+	markdown: string,
+	hiddenTitle: HiddenTitleHeading | null,
+): string {
+	if (!hiddenTitle) return markdown;
+	return `${hiddenTitle.headingPrefix} ${hiddenTitle.title}\n\n${markdown}`;
+}

tests/title-visibility.test.mjs

@@ -0,0 +1,104 @@
+import assert from 'node:assert/strict';
+import { readFile } from 'node:fs/promises';
+import test from 'node:test';
+
+const { restoreTitleHeading, stripTitleHeading } = await import(
+  new URL('../src/lib/editor/titleVisibility.ts', import.meta.url)
+);
+const editorSource = await readFile(
+  new URL('../src/lib/components/Editor.svelte', import.meta.url),
+  'utf8'
+);
+
+test('rich to source transition strips the restored title before display', () => {
+  const start = editorSource.indexOf('if (isSource && !lastSourceMode) {');
+  const end = editorSource.indexOf('} else if (!isSource && lastSourceMode)', start);
+
+  assert.notEqual(start, -1, 'rich to source transition was not found');
+  assert.notEqual(end, -1, 'rich to source transition boundary was not found');
+  assert.match(
+    editorSource.slice(start, end),
+    /sourceContent\s*=\s*stripTitleH1\(\s*editor\s*\?\s*editorToMarkdown\(\)\s*:\s*\(\$activeNote\?\.content\s*\?\?\s*''\)\s*\)\s*;/
+  );
+});
+
+test('source to rich transition preserves the hidden title on desktop and mobile', () => {
+  const start = editorSource.indexOf('} else if (!isSource && lastSourceMode) {');
+  const end = editorSource.indexOf('// Tauri drag-drop listener', start);
+  const transition = editorSource.slice(start, end);
+
+  assert.notEqual(start, -1, 'source to rich transition was not found');
+  assert.notEqual(end, -1, 'source to rich transition boundary was not found');
+  assert.match(
+    transition,
+    /editor\.commands\.setContent\(\s*markdownToHtml\(\s*restoreTitleH1\(\s*content\s*\)\s*\)\s*\)\s*;/
+  );
+  assert.match(transition, /createEditor\(\s*restoreTitleH1\(\s*content\s*\)\s*\)\s*;/);
+});
+
+test('source to rich transition preserves an empty source body on desktop and mobile', () => {
+  const start = editorSource.indexOf('} else if (!isSource && lastSourceMode) {');
+  const end = editorSource.indexOf('// Tauri drag-drop listener', start);
+  const transition = editorSource.slice(start, end);
+  const contentAssignments = [...transition.matchAll(/const content = ([^;]+);/g)]
+    .map((match) => match[1].trim());
+
+  assert.deepEqual(contentAssignments, ['srcText', 'srcText']);
+  assert.doesNotMatch(transition, /srcText\s*\|\|/);
+});
+
+test('keeps a hidden title through source to rich to source and save', () => {
+  const persisted = '# Note title\n\n## Something else\n\nBody\n';
+  const body = '## Something else\n\nBody\n';
+
+  const initialSource = stripTitleHeading(persisted, 'Note title', true);
+  const rich = stripTitleHeading(
+    restoreTitleHeading(initialSource.markdown, initialSource.hiddenTitle),
+    'Note title',
+    true
+  );
+  const toggledSource = stripTitleHeading(
+    restoreTitleHeading(rich.markdown, rich.hiddenTitle),
+    'Note title',
+    true
+  );
+
+  assert.equal(rich.markdown, body);
+  assert.equal(toggledSource.markdown, body);
+  assert.equal(restoreTitleHeading(toggledSource.markdown, toggledSource.hiddenTitle), persisted);
+});
+
+test('keeps a title-only note visually empty and saves one title heading', () => {
+  const initialSource = stripTitleHeading('# Note title\n', 'Note title', true);
+  const rich = stripTitleHeading(
+    restoreTitleHeading(initialSource.markdown, initialSource.hiddenTitle),
+    'Note title',
+    true
+  );
+  const saved = restoreTitleHeading(rich.markdown, rich.hiddenTitle);
+
+  assert.equal(initialSource.markdown, '');
+  assert.equal(rich.markdown, '');
+  assert.equal((saved.match(/^# Note title$/gm) ?? []).length, 1);
+});
+
+test('replaces hidden title state when an unrelated note loads', () => {
+  const markdown = '## Something else\n\nOther body\n';
+  const start = editorSource.indexOf('function stripTitleH1(md: string): string {');
+  const end = editorSource.indexOf('function restoreTitleH1(md: string): string {', start);
+
+  assert.deepEqual(stripTitleHeading(markdown, 'Another note', true), {
+    markdown,
+    hiddenTitle: null
+  });
+  assert.match(editorSource.slice(start, end), /hiddenTitleHeading\s*=\s*result\.hiddenTitle\s*;/);
+});
+
+test('leaves the title visible when title hiding is disabled', () => {
+  const persisted = '# Note title\n\n## Something else\n';
+
+  assert.deepEqual(stripTitleHeading(persisted, 'Note title', false), {
+    markdown: persisted,
+    hiddenTitle: null
+  });
+});