feat(watchlist): yaml helpers + schema types

packages/obsidian/src/watchlist/yaml.ts

@@ -0,0 +1,25 @@
+const NEEDS_QUOTE = /[:,#\[\]{}"&*!|>%@`]/;
+const KEYWORDS = new Set(['null', 'true', 'false', 'yes', 'no']);
+
+export function yamlScalar(v: unknown): string {
+	if (v === null || v === undefined || v === '') return '';
+	const s = String(v);
+	if (NEEDS_QUOTE.test(s) || s.trim() !== s || KEYWORDS.has(s.toLowerCase())) {
+		return '"' + s.replace(/"/g, '\\"') + '"';
+	}
+	return s;
+}
+
+export function yamlList(items: string[]): string {
+	const parts: string[] = [];
+	for (const raw of items) {
+		const g = String(raw).trim();
+		if (!g) continue;
+		parts.push(/^[A-Za-z0-9 ]+$/.test(g) ? g : '"' + g.replace(/"/g, '\\"') + '"');
+	}
+	return '[' + parts.join(', ') + ']';
+}
+
+export function quotedOrNull(v: string | null | undefined): string {
+	return v ? '"' + v + '"' : 'null';
+}