diff --git a/src/config.test.ts b/src/config.test.ts
new file mode 100644
index 0000000..eb752fa
--- /dev/null
+++ b/src/config.test.ts
@@ -0,0 +1,27 @@
+import { describe, expect, it } from "vitest";
+import { SettingKey, getConfigSection, getSettingDefault } from "./config";
+
+describe("config", () => {
+	it("getConfigSection returns the section prefix from package.json", () => {
+		const section = getConfigSection();
+		expect(typeof section).toBe("string");
+		expect(section).not.toHaveLength(0);
+	});
+
+	it("getSettingDefault returns a non-empty default for projectPath", () => {
+		const value = getSettingDefault("projectPath");
+		expect(typeof value).toBe("string");
+		expect(value).not.toHaveLength(0);
+	});
+
+	it("getSettingDefault returns a string for globalPath (may be empty)", () => {
+		const value = getSettingDefault("globalPath");
+		expect(typeof value).toBe("string");
+	});
+
+	it("throws for missing setting key", () => {
+		expect(() => getSettingDefault("missing" as SettingKey)).toThrow(
+			"Missing package.json setting",
+		);
+	});
+});
diff --git a/src/model/taskFile.test.ts b/src/model/taskFile.test.ts
new file mode 100644
index 0000000..e4063d7
--- /dev/null
+++ b/src/model/taskFile.test.ts
@@ -0,0 +1,39 @@
+import { describe, expect, it } from "vitest";
+import {
+	MAX_TASK_TITLE_LENGTH,
+	TASK_FILE_EXTENSION,
+	TASK_LANGUAGE_ID,
+	isTaskFileName,
+} from "./taskFile";
+
+describe("taskFile", () => {
+	it("package.json defines a non-empty file extension", () => {
+		expect(typeof TASK_FILE_EXTENSION).toBe("string");
+		expect(TASK_FILE_EXTENSION).not.toHaveLength(0);
+	});
+
+	it("package.json defines a non-empty language id", () => {
+		expect(typeof TASK_LANGUAGE_ID).toBe("string");
+		expect(TASK_LANGUAGE_ID).not.toHaveLength(0);
+	});
+
+	it("max title length is a positive number", () => {
+		expect(typeof MAX_TASK_TITLE_LENGTH).toBe("number");
+		expect(Number.isFinite(MAX_TASK_TITLE_LENGTH)).toBe(true);
+		expect(MAX_TASK_TITLE_LENGTH).toBeGreaterThan(0);
+	});
+
+	it("isTaskFileName uses the configured extension", () => {
+		expect(isTaskFileName(`task${TASK_FILE_EXTENSION}`)).toBe(true);
+		expect(isTaskFileName(TASK_FILE_EXTENSION)).toBe(true);
+	});
+
+	it("isTaskFileName rejects non-matching extensions", () => {
+		expect(isTaskFileName("task.md")).toBe(false);
+		expect(isTaskFileName("task.xflow")).toBe(false);
+	});
+
+	it("isTaskFileName rejects empty string", () => {
+		expect(isTaskFileName("")).toBe(false);
+	});
+});