fix(daemon): use correct systemd user target and isolate test cache

internal/cmd/daemon_install.go

@@ -22,11 +22,10 @@ Type=simple
 ExecStart={{.BinPath}} start
 Restart=always
 RestartSec=10
-User={{.User}}
 Environment=HOME={{.Home}}
 
 [Install]
-WantedBy=multi-user.target
+WantedBy=default.target
 `
 
 const launchdTemplate = `<?xml version="1.0" encoding="UTF-8"?>

internal/upgrade/cache.go

@@ -18,15 +18,17 @@ type versionCache struct {
 	CheckedAt time.Time `json:"checkedAt"`
 }
 
-// cacheFilePath returns the path to the version cache file.
+// cacheFilePathFn returns the path to the version cache file.
-func cacheFilePath() string {
+// Overridable in tests to avoid polluting the real cache.
+// NOTE: not safe for parallel tests — callers must not use t.Parallel().
+var cacheFilePathFn = func() string {
 	return filepath.Join(config.DataDir(), "latest-version.json")
 }
 
 // ReadCachedVersion returns the cached latest version if it's fresh (< cacheTTL).
 // Returns empty string if cache is missing, stale, or corrupt.
 func ReadCachedVersion() string {
-	data, err := os.ReadFile(cacheFilePath())
+	data, err := os.ReadFile(cacheFilePathFn())
 	if err != nil {
 		return ""
 	}
@@ -50,14 +52,16 @@ func writeCachedVersion(version string) {
 	if err != nil {
 		return
 	}
-	path := cacheFilePath()
+	path := cacheFilePathFn()
 	os.MkdirAll(filepath.Dir(path), 0o755)
 	// Best-effort write — ignore errors
 	tmp := path + ".tmp"
 	if err := os.WriteFile(tmp, data, 0o644); err != nil {
 		return
 	}
-	os.Rename(tmp, path)
+	if os.Rename(tmp, path) != nil {
+		os.Remove(tmp)
+	}
 }
 
 // CheckLatestCached returns the latest version, using cache when fresh.

internal/upgrade/upgrade_test.go

@@ -316,6 +316,16 @@ func swapHTTPClient(c *http.Client) func() {
 	return func() { httpClient = orig }
 }
 
+// swapCacheDir redirects the version cache to a temp directory to avoid
+// polluting the real ~/.local/share/unarr/latest-version.json during tests.
+func swapCacheDir(t *testing.T) func() {
+	t.Helper()
+	tmpDir := t.TempDir()
+	orig := cacheFilePathFn
+	cacheFilePathFn = func() string { return filepath.Join(tmpDir, "latest-version.json") }
+	return func() { cacheFilePathFn = orig }
+}
+
 // rewriteTransport redirects all requests to the given base URL,
 // preserving path and query.
 type rewriteTransport struct {
@@ -563,6 +573,10 @@ func TestFetchLatestVersionWithHTTPTest(t *testing.T) {
 			})
 			defer restore()
 
+			// Redirect cache to temp dir so tests don't pollute the real cache
+			restoreCache := swapCacheDir(t)
+			defer restoreCache()
+
 			ver, err := CheckLatest(context.Background())
 			if tt.wantErr {
 				if err == nil {