Upgrade to Go 1.26 and resolve all golangci-lint findings

- Bump go.mod to Go 1.26, run go fix for automatic modernisation
  (intrange loops, strings.Builder, code deduplication)
- Fix correctness bugs: nilerr in group delete, errorlint (errors.Is/As,
  %w wrapping), ineffassign, contextcheck, bodyclose in tests
- Fix all errcheck findings: safe type assertions, checked Render/Close/
  SetDeadline returns, checked BindPFlag/yaml.Unmarshal/json.Encode
- Fix perfsprint: errors.New for static strings, string concat, strconv
- Fix goimports formatting across all files
- Fix noctx: context-aware net.Dial/http.NewRequest in prod and tests
- Fix sloglint: slog.DiscardHandler in test loggers
- Fix staticcheck/wastedassign/unparam/usestdlibvars
- Fix gosec: tighten file permissions, nolint for false positives
- Add nolint:misspell for intentional British spellings
- Add separate validateTimeout for discovery light validation
- Add discovery_test.go with validation context isolation tests

golangci-lint: 250 findings -> 0

Author: jmylchreest

cmd/keylight-openapi/main.go

@@ -69,7 +69,7 @@ func main() {
 
 	// Output to file or stdout
 	if *outputFile != "" {
-		if err := os.WriteFile(*outputFile, data, 0644); err != nil {
+		if err := os.WriteFile(*outputFile, data, 0600); err != nil {
 			fmt.Fprintf(os.Stderr, "error writing to file: %v\n", err)
 			os.Exit(1)
 		}

cmd/keylightctl/commands/apikey.go

@@ -1,15 +1,17 @@
 package commands
 
 import (
+	"errors"
 	"fmt"
 	"log/slog"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/jmylchreest/keylightd/pkg/client"
 	"github.com/pterm/pterm"
 	"github.com/spf13/cobra"
+
+	"github.com/jmylchreest/keylightd/pkg/client"
 )
 
 // NewAPIKeyCommand creates the apikey command group.
@@ -45,7 +47,7 @@ func newAPIKeyListCommand(_ *slog.Logger) *cobra.Command {
 		RunE: func(cmd *cobra.Command, args []string) error {
 			apiClient, ok := cmd.Context().Value(clientContextKey).(client.ClientInterface)
 			if !ok {
-				return fmt.Errorf("client not found in context")
+				return errors.New("client not found in context")
 			}
 
 			keys, err := apiClient.ListAPIKeys()
@@ -112,7 +114,9 @@ func newAPIKeyListCommand(_ *slog.Logger) *cobra.Command {
 					strconv.FormatBool(enabledBool),
 				})
 			}
-			pterm.DefaultTable.WithHasHeader().WithData(table).Render()
+			if err := pterm.DefaultTable.WithHasHeader().WithData(table).Render(); err != nil {
+				return fmt.Errorf("failed to render table: %w", err)
+			}
 			return nil
 		},
 	}
@@ -131,7 +135,7 @@ func newAPIKeyAddCommand(_ *slog.Logger) *cobra.Command {
 		RunE: func(cmd *cobra.Command, args []string) error {
 			apiClient, ok := cmd.Context().Value(clientContextKey).(client.ClientInterface)
 			if !ok {
-				return fmt.Errorf("client not found in context")
+				return errors.New("client not found in context")
 			}
 
 			// Get name: from arg 1, then flag, then prompt
@@ -147,7 +151,7 @@ func newAPIKeyAddCommand(_ *slog.Logger) *cobra.Command {
 					return fmt.Errorf("failed to get API key name: %w", err)
 				}
 				if name == "" {
-					return fmt.Errorf("API key name cannot be empty")
+					return errors.New("API key name cannot be empty")
 				}
 			}
 
@@ -229,10 +233,10 @@ func newAPIKeyDeleteCommand(_ *slog.Logger) *cobra.Command {
 		RunE: func(cmd *cobra.Command, args []string) error {
 			apiClient, ok := cmd.Context().Value(clientContextKey).(client.ClientInterface)
 			if !ok {
-				return fmt.Errorf("client not found in context")
+				return errors.New("client not found in context")
 			}
 
-			keyToDelete := ""
+			var keyToDelete string
 			if len(args) > 0 {
 				keyToDelete = args[0]
 			} else {
@@ -268,7 +272,7 @@ func newAPIKeyDeleteCommand(_ *slog.Logger) *cobra.Command {
 			}
 
 			if keyToDelete == "" {
-				return fmt.Errorf("no API key specified or selected for deletion")
+				return errors.New("no API key specified or selected for deletion")
 			}
 
 			// Confirm before deleting
@@ -279,7 +283,7 @@ func newAPIKeyDeleteCommand(_ *slog.Logger) *cobra.Command {
 					Show()
 
 				if !confirm {
-					pterm.Info.Println("API key deletion cancelled.")
+					pterm.Info.Println("API key deletion cancelled.") //nolint:misspell
 					return nil
 				}
 			}
@@ -306,7 +310,7 @@ func newAPIKeySetEnabledCommand(_ *slog.Logger) *cobra.Command {
 		RunE: func(cmd *cobra.Command, args []string) error {
 			apiClient, ok := cmd.Context().Value(clientContextKey).(client.ClientInterface)
 			if !ok {
-				return fmt.Errorf("client not found in context")
+				return errors.New("client not found in context")
 			}
 
 			var keyToUpdate string
@@ -318,14 +322,14 @@ func newAPIKeySetEnabledCommand(_ *slog.Logger) *cobra.Command {
 			}
 
 			if len(args) > 1 {
-				statusStr := strings.ToLower(args[1])
-				if statusStr == "true" || statusStr == "enabled" {
+				switch strings.ToLower(args[1]) {
+				case "true", "enabled":
 					desiredEnabledState = true
 					statusArgProvided = true
-				} else if statusStr == "false" || statusStr == "disabled" {
+				case "false", "disabled":
 					desiredEnabledState = false
 					statusArgProvided = true
-				} else {
+				default:
 					return fmt.Errorf("invalid status argument: %s. Must be true, false, enabled, or disabled", args[1])
 				}
 			}

cmd/keylightctl/commands/apikey_test.go

@@ -8,8 +8,9 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/jmylchreest/keylightd/pkg/client"
 	"github.com/stretchr/testify/require"
+
+	"github.com/jmylchreest/keylightd/pkg/client"
 )
 
 type mockAPIKeyClient struct {

cmd/keylightctl/commands/format.go

@@ -3,11 +3,13 @@ package commands
 import (
 	"encoding/json"
 	"fmt"
+	"strconv"
 	"strings"
 	"time"
 
-	"github.com/jmylchreest/keylightd/pkg/keylight"
 	"github.com/pterm/pterm"
+
+	"github.com/jmylchreest/keylightd/pkg/keylight"
 )
 
 // WaybarOutput represents the JSON format expected by waybar custom modules
@@ -103,14 +105,14 @@ func LightToJSON(id string, light map[string]any) LightJSON {
 
 // GroupToJSON converts a group map to GroupJSON struct
 func GroupToJSON(group map[string]any) GroupJSON {
-	id := group["id"].(string)
-	name := group["name"].(string)
+	id, _ := group["id"].(string)
+	name, _ := group["name"].(string)
 
 	var lightIDs []string
 	if lights, ok := group["lights"].([]any); ok {
 		lightIDs = make([]string, len(lights))
 		for i, light := range lights {
-			lightIDs[i] = light.(string)
+			lightIDs[i], _ = light.(string)
 		}
 	}
 
@@ -130,7 +132,7 @@ func FormatWaybarOutput(lights map[string]any) string {
 	var tooltipLines []string
 
 	for id, light := range lights {
-		lightMap := light.(map[string]any)
+		lightMap, _ := light.(map[string]any)
 		name := keylight.UnescapeRFC6763Label(id)
 
 		on := false
@@ -155,7 +157,7 @@ func FormatWaybarOutput(lights map[string]any) string {
 			tooltipLines = append(tooltipLines, fmt.Sprintf("%s: %d%% @ %dK", name, brightness, tempKelvin))
 		} else {
 			offCount++
-			tooltipLines = append(tooltipLines, fmt.Sprintf("%s: off", name))
+			tooltipLines = append(tooltipLines, name+": off")
 		}
 	}
 
@@ -226,7 +228,7 @@ func LightParseable(id string, light map[string]any) string {
 	id = keylight.UnescapeRFC6763Label(id)
 	lastSeenUnix := "0"
 	if t, ok := light["lastseen"].(time.Time); ok && !t.IsZero() {
-		lastSeenUnix = fmt.Sprintf("%d", t.Unix())
+		lastSeenUnix = strconv.FormatInt(t.Unix(), 10)
 	}
 	tempDevice := 0
 	if v, ok := light["temperature"].(int); ok {
@@ -252,12 +254,12 @@ func LightParseable(id string, light map[string]any) string {
 
 // GroupParseable returns the parseable string for a group (id, name, lights as comma-separated)
 func GroupParseable(group map[string]any) string {
-	id := group["id"].(string)
-	name := group["name"].(string)
-	lights := group["lights"].([]any)
+	id, _ := group["id"].(string)
+	name, _ := group["name"].(string)
+	lights, _ := group["lights"].([]any)
 	lightIDs := make([]string, len(lights))
 	for i, light := range lights {
-		lightIDs[i] = light.(string)
+		lightIDs[i], _ = light.(string)
 	}
 	return fmt.Sprintf("id=\"%s\" name=\"%s\" lights=\"%s\"", id, name, strings.Join(lightIDs, ","))
 }