fix: return an error from CheckForUpdate instead of conflating failure with no-update

internal/app/app.go

@@ -12,6 +12,7 @@ import (
 	tea "github.com/charmbracelet/bubbletea"
 	"unic/internal/config"
 	"unic/internal/domain"
+	uniclog "unic/internal/log"
 	awsservice "unic/internal/services/aws"
 	"unic/internal/update"
 )
@@ -293,7 +294,10 @@ var appLoadCallerIdentityFn = func(m Model) tea.Cmd {
 func (m Model) checkForUpdate() tea.Cmd {
 	return func() tea.Msg {
 		method := update.DetectInstallMethod()
-		newVersion := update.CheckForUpdate(m.currentVersion)
+		newVersion, err := update.CheckForUpdate(m.currentVersion)
+		if err != nil {
+			uniclog.Info("app", "update check failed", "error", err.Error())
+		}
 		return updateAvailableMsg{version: newVersion, method: method}
 	}
 }

internal/update/update.go

@@ -147,34 +147,38 @@ func CheckLatestVersion() (string, error) {
 	return release.TagName, nil
 }
 
+// checkLatestVersionFn is a test seam for the GitHub releases API call.
+var checkLatestVersionFn = CheckLatestVersion
+
 // CheckForUpdate checks if a newer version is available, using cache when possible.
 // Returns the new version string if available, or empty string if up to date.
-func CheckForUpdate(currentVersion string) string {
+// A non-nil error means the check itself failed and no result is known.
+func CheckForUpdate(currentVersion string) (string, error) {
 	if currentVersion == "dev" {
-		return ""
+		return "", nil
 	}
 
 	// Try cache first
 	if !ShouldCheck() {
 		c, err := readCache()
 		if err == nil && IsNewer(currentVersion, c.Version) {
-			return c.Version
+			return c.Version, nil
 		}
-		return ""
+		return "", nil
 	}
 
-	latest, err := CheckLatestVersion()
+	latest, err := checkLatestVersionFn()
 	if err != nil {
-		return ""
+		return "", fmt.Errorf("update check failed: %w", err)
 	}
 
 	// Update cache regardless of result
 	_ = writeCache(latest)
 
 	if IsNewer(currentVersion, latest) {
-		return latest
+		return latest, nil
 	}
-	return ""
+	return "", nil
 }
 
 // IsNewer returns true if latest is a newer version than current.

internal/update/update_test.go

@@ -1,6 +1,8 @@
 package update
 
 import (
+	"errors"
+	"strings"
 	"testing"
 )
 
@@ -113,8 +115,45 @@ func TestWriteAndReadCache(t *testing.T) {
 
 func TestCheckForUpdate_DevVersion(t *testing.T) {
 	// dev version should never trigger update check
-	result := CheckForUpdate("dev")
+	result, err := CheckForUpdate("dev")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
 	if result != "" {
 		t.Errorf("expected empty string for dev version, got %q", result)
 	}
 }
+
+func TestCheckForUpdate_PropagatesCheckError(t *testing.T) {
+	t.Setenv("XDG_CONFIG_HOME", t.TempDir())
+	orig := checkLatestVersionFn
+	t.Cleanup(func() { checkLatestVersionFn = orig })
+	checkLatestVersionFn = func() (string, error) {
+		return "", errors.New("api down")
+	}
+
+	result, err := CheckForUpdate("0.1.0")
+	if err == nil || !strings.Contains(err.Error(), "api down") {
+		t.Fatalf("expected wrapped check error, got %v", err)
+	}
+	if result != "" {
+		t.Errorf("expected empty version on error, got %q", result)
+	}
+}
+
+func TestCheckForUpdate_ReturnsNewerVersion(t *testing.T) {
+	t.Setenv("XDG_CONFIG_HOME", t.TempDir())
+	orig := checkLatestVersionFn
+	t.Cleanup(func() { checkLatestVersionFn = orig })
+	checkLatestVersionFn = func() (string, error) {
+		return "v0.2.0", nil
+	}
+
+	result, err := CheckForUpdate("0.1.0")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if result != "v0.2.0" {
+		t.Errorf("expected v0.2.0, got %q", result)
+	}
+}