feat: add tags workflow

src/frontmatter/validateFrontmatter.test.ts

@@ -93,4 +93,38 @@ title: [unterminated
 		const issues = validateFrontmatter(content);
 		expect(issues.some((i) => /yaml/i.test(i.message))).toBe(true);
 	});
+
+	it("does not warn about unknown tags when knownTags is omitted", () => {
+		const issues = validateFrontmatter(valid);
+		expect(issues.filter((i) => i.field === "tags")).toEqual([]);
+	});
+
+	it("warns when a tag is not in knownTags", () => {
+		const content = valid.replace("tags: [bug]", "tags: [bug, nope]");
+		const issues = validateFrontmatter(content, { knownTags: ["bug"] });
+		const unknown = issues.filter(
+			(i) => i.field === "tags" && i.severity === "warning",
+		);
+		expect(unknown).toHaveLength(1);
+		expect(unknown[0].message).toMatch(/nope/i);
+	});
+
+	it("does not warn when all tags are known", () => {
+		const issues = validateFrontmatter(valid, {
+			knownTags: ["bug", "frontend"],
+		});
+		expect(issues.filter((i) => i.severity === "warning")).toEqual([]);
+	});
+
+	it("warns for every tag when knownTags is empty array (config exists)", () => {
+		const issues = validateFrontmatter(valid, { knownTags: [] });
+		expect(
+			issues.some(
+				(i) =>
+					i.field === "tags" &&
+					i.severity === "warning" &&
+					/bug/i.test(i.message),
+			),
+		).toBe(true);
+	});
 });