test(auth): keep portable fixtures platform-neutral

internal/auth/coverage_edges_test.go

@@ -1234,6 +1234,12 @@ func TestCrossPlatformCoveragePortableAuthBundleCoverageEdges(t *testing.T) {
 	})
 
 	t.Run("import validation", func(t *testing.T) {
+		oldGOOS := portableRuntimeGOOS
+		t.Cleanup(func() {
+			portableRuntimeGOOS = oldGOOS
+		})
+		portableRuntimeGOOS = func() string { return "linux" }
+
 		t.Setenv(keychain.StorageDirEnv, t.TempDir())
 		if _, err := ImportPortableAuthBundle(t.TempDir(), nil); err == nil {
 			t.Fatal("nil portable reader succeeded")

internal/auth/remaining_coverage_test.go

@@ -91,6 +91,7 @@ func TestCrossPlatformCoverageTokenPersistencePreflightRemainingEdges(t *testing
 }
 
 func TestCrossPlatformCoveragePortableExportRemainingEdges(t *testing.T) {
+	origGOOS := portableRuntimeGOOS
 	origStat := portableStat
 	origConfigFiles := portableConfigFilesForExport
 	origManifest := portableWriteManifest
@@ -99,6 +100,7 @@ func TestCrossPlatformCoveragePortableExportRemainingEdges(t *testing.T) {
 	origKeychainGet := authKeychainGet
 	origKeychainExists := authKeychainExists
 	t.Cleanup(func() {
+		portableRuntimeGOOS = origGOOS
 		portableStat = origStat
 		portableConfigFilesForExport = origConfigFiles
 		portableWriteManifest = origManifest
@@ -107,6 +109,7 @@ func TestCrossPlatformCoveragePortableExportRemainingEdges(t *testing.T) {
 		authKeychainGet = origKeychainGet
 		authKeychainExists = origKeychainExists
 	})
+	portableRuntimeGOOS = func() string { return "linux" }
 
 	t.Setenv(keychain.StorageDirEnv, t.TempDir())
 	t.Setenv(keychain.DisableKeychainEnv, "1")