fix: fix plan mode path resolution on Windows (#365)

Co-authored-by: Letta <noreply@letta.com>

src/cli/helpers/planName.ts

@@ -1,4 +1,5 @@
 import { homedir } from "node:os";
+import { join } from "node:path";
 
 const adjectives = [
   "bold",
@@ -113,5 +114,5 @@ export function generatePlanName(): string {
 
 export function generatePlanFilePath(): string {
   const name = generatePlanName();
-  return `${homedir()}/.letta/plans/${name}.md`;
+  return join(homedir(), ".letta", "plans", `${name}.md`);
 }

src/tests/helpers/planName.test.ts

@@ -0,0 +1,28 @@
+import { expect, test } from "bun:test";
+import { sep } from "node:path";
+import {
+  generatePlanFilePath,
+  generatePlanName,
+} from "../../cli/helpers/planName";
+
+test("generatePlanName returns valid format", () => {
+  const name = generatePlanName();
+  expect(name).toMatch(/^[a-z]+-[a-z]+-[a-z]+$/);
+});
+
+test("generatePlanFilePath uses platform-specific path separator", () => {
+  const path = generatePlanFilePath();
+  expect(path).toContain(sep);
+  expect(path).toMatch(/\.letta.+plans.+/);
+});
+
+test("generatePlanFilePath ends with .md extension", () => {
+  const path = generatePlanFilePath();
+  expect(path).toMatch(/\.md$/);
+});
+
+test("generatePlanFilePath contains valid plan name structure", () => {
+  const path = generatePlanFilePath();
+  const basename = path.split(sep).pop();
+  expect(basename).toMatch(/^[a-z]+-[a-z]+-[a-z]+\.md$/);
+});