refactor: move shared utilities to lib/shared/ sub-packages

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

frontend/src/lib/shared/discussion/mentionSerializer.ts

@@ -0,0 +1,113 @@
+import type { JSONContent } from '@tiptap/core';
+import type { PersonMention } from '$lib/types';
+
+/**
+ * Converts stored block text + sidecar into a Tiptap ProseMirror document.
+ *
+ * The text is split by "\n" into paragraphs. Within each paragraph, sidecar
+ * entries are matched against "@displayName" tokens (longest first) and
+ * converted to mention nodes. Unmatched text becomes plain text nodes.
+ *
+ * Round-trip invariant: serialize(deserialize(text, sidecar)).text === text
+ */
+export function deserialize(text: string, sidecar: PersonMention[]): JSONContent {
+	const lines = text === '' ? [''] : text.split('\n');
+
+	// Sort sidecar by displayName length descending so longer names shadow
+	// shorter prefix matches (same heuristic as renderTranscriptionBody).
+	const sorted = [...sidecar].sort((a, b) => b.displayName.length - a.displayName.length);
+
+	return {
+		type: 'doc',
+		content: lines.map((line) => ({
+			type: 'paragraph',
+			content: parseLine(line, sorted)
+		}))
+	};
+}
+
+function parseLine(text: string, sidecar: PersonMention[]): JSONContent[] {
+	if (text === '') return [];
+
+	if (sidecar.length === 0) {
+		return [{ type: 'text', text }];
+	}
+
+	// Build a list of mention ranges: { start, end, mention }
+	const ranges: Array<{ start: number; end: number; mention: PersonMention }> = [];
+
+	for (const mention of sidecar) {
+		const needle = `@${mention.displayName}`;
+		let idx = 0;
+		while (idx < text.length) {
+			const pos = text.indexOf(needle, idx);
+			if (pos === -1) break;
+			// Check that the range doesn't overlap an already-found range
+			const end = pos + needle.length;
+			const overlaps = ranges.some((r) => r.start < end && r.end > pos);
+			if (!overlaps) {
+				ranges.push({ start: pos, end, mention });
+			}
+			idx = pos + 1;
+		}
+	}
+
+	if (ranges.length === 0) {
+		return [{ type: 'text', text }];
+	}
+
+	// Sort by position
+	ranges.sort((a, b) => a.start - b.start);
+
+	const nodes: JSONContent[] = [];
+	let cursor = 0;
+
+	for (const { start, end, mention } of ranges) {
+		if (start > cursor) {
+			nodes.push({ type: 'text', text: text.slice(cursor, start) });
+		}
+		nodes.push({
+			type: 'mention',
+			attrs: { displayName: mention.displayName, personId: mention.personId }
+		});
+		cursor = end;
+	}
+
+	if (cursor < text.length) {
+		nodes.push({ type: 'text', text: text.slice(cursor) });
+	}
+
+	return nodes;
+}
+
+/**
+ * Converts a Tiptap ProseMirror document back to stored block text + sidecar.
+ *
+ * Paragraphs are joined with "\n". Mention nodes are emitted as "@displayName"
+ * and collected into mentionedPersons (de-duplicated by personId).
+ */
+export function serialize(doc: JSONContent): { text: string; mentionedPersons: PersonMention[] } {
+	const paragraphs = doc.content ?? [];
+	const mentionedPersons: PersonMention[] = [];
+	const seenIds = new Set<string>();
+	const lines: string[] = [];
+
+	for (const para of paragraphs) {
+		let line = '';
+		for (const node of para.content ?? []) {
+			if (node.type === 'text') {
+				line += node.text ?? '';
+			} else if (node.type === 'mention') {
+				const { displayName, personId } = node.attrs ?? {};
+				line += `@${displayName}`;
+				if (!seenIds.has(personId)) {
+					seenIds.add(personId);
+					mentionedPersons.push({ personId, displayName });
+				}
+			}
+		}
+		lines.push(line);
+	}
+
+	return { text: lines.join('\n'), mentionedPersons };
+}