feat: add inline icons for edit

src/frontmatter/frontmatterFields.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import { findFieldRange, replaceFrontmatterField } from "./frontmatterFields";
+
+const sample = `---
+id: abc
+title: Hello
+status: todo
+priority: medium
+---
+
+Body
+`;
+
+describe("replaceFrontmatterField", () => {
+	it("replaces status value", () => {
+		const result = replaceFrontmatterField(sample, "status", "done");
+		expect(result.ok).toBe(true);
+		if (!result.ok) return;
+		expect(result.content).toContain("status: done");
+		expect(result.content).toContain("title: Hello");
+		expect(result.content).toContain("Body");
+	});
+
+	it("replaces priority value", () => {
+		const result = replaceFrontmatterField(sample, "priority", "critical");
+		expect(result.ok).toBe(true);
+		if (!result.ok) return;
+		expect(result.content).toContain("priority: critical");
+	});
+
+	it("fails when field is missing", () => {
+		const result = replaceFrontmatterField(sample, "assignee", "me");
+		expect(result).toEqual({ ok: false, reason: "no-field" });
+	});
+
+	it("fails without frontmatter", () => {
+		const result = replaceFrontmatterField("plain", "status", "todo");
+		expect(result).toEqual({ ok: false, reason: "no-frontmatter" });
+	});
+});
+
+describe("findFieldRange", () => {
+	it("points at the value column", () => {
+		const range = findFieldRange(sample, "status");
+		expect(range).toBeDefined();
+		const line = sample.split("\n")[range!.startLine];
+		expect(line.slice(range!.startCol, range!.endCol)).toBe("todo");
+	});
+});