refactor: improve resource cleanup and logging in various functions

Author: ToeiRei

cmd/keymaster/main.go

@@ -875,7 +875,7 @@ Example (Full Restore):
 		if err != nil {
 			log.Fatalf("%s", i18n.T("restore.cli_error_read", err))
 		}
-		defer f.Close()
+		defer func() { _ = f.Close() }()
 		if err := core.RunRestoreCmd(cmd.Context(), f, core.RestoreOptions{Full: fullRestore}, &cliStoreAdapter{}); err != nil {
 			log.Fatalf("%s", i18n.T("restore.cli_error_import", err))
 		}
@@ -946,7 +946,7 @@ Examples:
 		if err != nil {
 			log.Fatalf("%s", i18n.T("backup.cli_error_write", err))
 		}
-		defer outf.Close()
+		defer func() { _ = outf.Close() }()
 		if err := core.RunWriteBackupCmd(cmd.Context(), data, outf); err != nil {
 			log.Fatalf("%s", i18n.T("backup.cli_error_write", err))
 		}

internal/core/bootstrap_contract.go

@@ -202,7 +202,8 @@ func PerformBootstrapDeployment(ctx context.Context, params BootstrapParams, dep
 					return res, fmt.Errorf("failed to assign key %d: %w", kid, err)
 				}
 			} else {
-				// Not fatal: warn and continue
+				// Not fatal: warn and continue — record a warning so callers know assignment was skipped.
+				res.Warnings = append(res.Warnings, fmt.Sprintf("no AssignKey dependency; skipped assigning key %d", kid))
 			}
 		}
 	}
@@ -261,7 +262,9 @@ func PerformBootstrapDeployment(ctx context.Context, params BootstrapParams, dep
 
 	// Update or remove persisted bootstrap session state if a store was provided.
 	if params.HostKey != "" || params.TempPrivateKey != "" {
-		// noop - params contain keys but session lifecycle is controlled by SessionStore below.
+		// Intentional no-op; reference fields to avoid empty branch warnings.
+		_ = params.HostKey
+		_ = params.TempPrivateKey
 	}
 
 	if paramsTemp := params; paramsTemp.SessionID != "" {

internal/core/facades.go

@@ -187,7 +187,7 @@ func WriteBackup(ctx context.Context, data *model.BackupData, w io.Writer) error
 	if err != nil {
 		return fmt.Errorf("create zstd writer: %w", err)
 	}
-	defer zw.Close()
+	defer func() { _ = zw.Close() }()
 	enc := json.NewEncoder(zw)
 	enc.SetIndent("", "  ")
 	if err := enc.Encode(data); err != nil {

internal/tui/debug/debug.go

@@ -25,7 +25,7 @@ func Launch() {
 	m := newTestModel()
 	if _, err := tea.NewProgram(&m).Run(); err != nil {
 		// On failure, print to stderr and exit non-zero to aid debugging.
-		os.Stderr.WriteString("test screen error: " + err.Error() + "\n")
+		_, _ = os.Stderr.WriteString("test screen error: " + err.Error() + "\n")
 		os.Exit(1)
 	}
 }