Add Clear Formatting action to editor context menu

src/lib/components/Editor.svelte

@@ -52,6 +52,7 @@
 	import { calloutGroup, calloutIcon, calloutLabel, CALLOUT_MENU, transformCalloutBlockquotes, serializeCallout } from '$lib/editor/callouts';
 	import { wrapTextareaSelection } from '$lib/editor/source/selectionPairs';
 	import { convertListNode, type MixedListName } from '$lib/editor/mixedLists';
+	import { clearFormatting } from '$lib/editor/clearFormatting';
 	import { serializeInlineMarkdown } from '$lib/editor/markdown';
 	import { relativePath } from '$lib/utils/paths';
 	import GraphView from './GraphView.svelte';
@@ -5079,6 +5080,11 @@
 		closeTextContextMenu();
 	}
 
+	function ctxClearFormatting() {
+		if (editor) clearFormatting(editor);
+		closeTextContextMenu();
+	}
+
 	function ctxCode() {
 		editor?.chain().focus().toggleCode().run();
 		closeTextContextMenu();
@@ -7201,6 +7207,10 @@
 				<svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M12 20h9"/><path d="M16.5 3.5a2.12 2.12 0 013 3L7 19l-4 1 1-4L16.5 3.5z"/></svg>
 				Highlight
 			</button>
+			<button onclick={ctxClearFormatting}>
+				<svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="m7 21-4.3-4.3c-1-1-1-2.5 0-3.4l9.6-9.6c1-1 2.5-1 3.4 0l5.6 5.6c1 1 1 2.5 0 3.4L13 21"/><path d="M22 21H7"/><path d="m5 11 9 9"/></svg>
+				Clear Formatting
+			</button>
 			<div class="text-ctx-sep"></div>
 			<button onclick={ctxLink}>
 				<svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 007.54.54l3-3a5 5 0 00-7.07-7.07l-1.72 1.71"/><path d="M14 11a5 5 0 00-7.54-.54l-3 3a5 5 0 007.07 7.07l1.71-1.71"/></svg>

src/lib/editor/clearFormatting.ts

@@ -0,0 +1,81 @@
+import type { Editor } from '@tiptap/core';
+import type { Schema } from '@tiptap/pm/model';
+import type { Transaction } from '@tiptap/pm/state';
+import { liftTarget } from '@tiptap/pm/transform';
+
+// Marks that carry content (URLs, note references) rather than visual
+// formatting. Clearing formatting must never destroy these.
+const CONTENT_MARKS: Record<string, true> = { link: true, wikiLink: true };
+
+// Block types reset to plain paragraphs. Lists, callouts, collapsible
+// sections and tables keep their structure so no state (checkboxes,
+// nesting, cells) is lost.
+const DEMOTE_BLOCKS: Record<string, true> = { heading: true, codeBlock: true };
+
+// Outermost-first position of the first blockquote intersecting [from, to].
+function findBlockquote(tr: Transaction, from: number, to: number): number | null {
+	let found: number | null = null;
+	tr.doc.nodesBetween(from, to, (node, pos) => {
+		if (found !== null) return false;
+		if (node.type.name === 'blockquote') {
+			found = pos;
+			return false;
+		}
+		return true;
+	});
+	return found;
+}
+
+/**
+ * Strips inline formatting and demotes heading/code-block/blockquote
+ * structure over the transaction's selection. An empty (cursor) selection
+ * is expanded to the whole current text block, so a single invocation can
+ * reset one messy line without highlighting it first.
+ */
+export function applyClearFormatting(schema: Schema, tr: Transaction): void {
+	const { selection } = tr;
+	const { $from } = selection;
+	const expandToBlock = selection.empty && $from.parent.isTextblock;
+	const from = expandToBlock ? $from.start() : selection.from;
+	const to = expandToBlock ? $from.end() : selection.to;
+
+	// 1. Strip formatting marks, keep content-bearing ones.
+	for (const mark of Object.values(schema.marks)) {
+		if (!CONTENT_MARKS[mark.name]) tr.removeMark(from, to, mark);
+	}
+
+	// 2. Demote headings and code blocks to paragraphs. Mark removal and
+	//    retyping never move content, so the original positions stay valid.
+	tr.doc.nodesBetween(from, to, (node, pos) => {
+		if (DEMOTE_BLOCKS[node.type.name]) tr.setNodeMarkup(pos, schema.nodes.paragraph);
+		return true;
+	});
+
+	// 3. Lift blockquote contents out of the quote wrapper, one pass per
+	//    nesting level. Lifts move positions, so remap and rescan each pass.
+	for (let guard = 0; guard < 20; guard++) {
+		const quotePos = findBlockquote(tr, tr.mapping.map(from, 1), tr.mapping.map(to, -1));
+		if (quotePos === null) break;
+		// The range must span the blockquote's content: a collapsed
+		// blockRange starts one depth up and wraps the quote itself.
+		const quote = tr.doc.nodeAt(quotePos);
+		if (!quote) break;
+		const range = tr.doc.resolve(quotePos + 1).blockRange(tr.doc.resolve(quotePos + quote.nodeSize - 1));
+		if (!range) break;
+		const target = liftTarget(range);
+		if (target === null) break;
+		tr.lift(range, target);
+	}
+}
+
+/** Clears formatting for the editor's current selection (or current line). */
+export function clearFormatting(editor: Editor): boolean {
+	return editor
+		.chain()
+		.focus()
+		.command(({ state, tr }) => {
+			applyClearFormatting(state.schema, tr);
+			return true;
+		})
+		.run();
+}