refactor: Fix additional linter issues (thelper, wastedassign, perfsprint)

Add new linters to golangci-lint: errchkjson, fatcontext, nilerr,
nosprintfhostport, canonicalheader, dupword, mirror, perfsprint,
predeclared, wastedassign, thelper.

Fixes include:
- Add t.Helper() to test setup functions (thelper)
- Use http.MethodPost/MethodGet constants (usestdlibvars)
- Use errors.As for wrapped error checking (errorlint)
- Use fmt.Sprintf instead of string concat in errors.New (perfsprint)
- Remove custom min() function (predeclared, Go 1.21 builtin)
- Fix wastedassign in event generators
- Fix nilerr by explicitly ignoring cache load error
- Use switch statements instead of if-else chains

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: cv

.golangci.yml

@@ -6,20 +6,31 @@ linters:
     - bodyclose          # HTTP response body closure
     - durationcheck      # Duration multiplication bugs
     - errorlint          # Error wrapping issues
+    - errchkjson         # JSON encoding error checks
+    - fatcontext         # Context misuse in loops
+    - nilerr             # Returns nil even when error set
     - noctx              # Missing context.Context usage
+    - nosprintfhostport  # URL construction bugs
 
     # Security
     - gosec              # Security issues
 
     # Code quality
+    - canonicalheader    # HTTP header canonicalization
+    - dupword            # Duplicate words (typos)
     - goconst            # Repeated strings that could be constants
     - gocritic           # Bugs, performance, style issues
+    - mirror             # bytes/strings usage patterns
     - misspell           # Typos
+    - perfsprint         # Faster alternatives to fmt.Sprintf
+    - predeclared        # Shadowing predeclared identifiers
     - unconvert          # Unnecessary type conversions
     - usestdlibvars      # Use stdlib constants
+    - wastedassign       # Wasted assignments
 
     # Test quality
     - testifylint        # Testify usage
+    - thelper            # Test helper best practices
 
   settings:
     goconst:

internal/api/auth.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -230,7 +231,7 @@ func (c *Client) GetEncryptionKeys(ctx context.Context) error {
 	}
 
 	if response.Payload == "" {
-		return fmt.Errorf("payload not found in response")
+		return errors.New("payload not found in response")
 	}
 
 	decrypted, err := c.decryptCheckVersionPayload(response.Payload)
@@ -280,7 +281,7 @@ func (c *Client) GetUsherEncryptionKey(ctx context.Context) (string, string, err
 	}
 
 	if response.Data.PublicKey == "" {
-		return "", "", fmt.Errorf("public key not found in response")
+		return "", "", errors.New("public key not found in response")
 	}
 
 	return response.Data.PublicKey, response.Data.VersionPrefix, nil
@@ -344,17 +345,17 @@ func (c *Client) Login(ctx context.Context) error {
 	}
 
 	if response.Status == "INVALID_CREDENTIAL" {
-		return fmt.Errorf("invalid email or password")
+		return errors.New("invalid email or password")
 	}
 	if response.Status == "USER_LOCKED" {
-		return fmt.Errorf("account is locked")
+		return errors.New("account is locked")
 	}
 	if response.Status != "OK" {
 		return fmt.Errorf("login failed with status: %s", response.Status)
 	}
 
 	if response.Data.AccessToken == "" {
-		return fmt.Errorf("access token not found in response")
+		return errors.New("access token not found in response")
 	}
 
 	c.accessToken = response.Data.AccessToken

internal/api/auth_test.go

@@ -28,7 +28,7 @@ func TestClient_GetEncryptionKeys(t *testing.T) {
 		assert.Equalf(t, "POST", r.Method, "Expected POST method, got %s", r.Method)
 
 		// Verify headers
-		assert.NotEmpty(t, r.Header.Get("app-code"), "Expected app-code header")
+		assert.NotEmpty(t, r.Header.Get("App-Code"), "Expected app-code header")
 
 		// Mock response - encrypt a simple JSON payload
 		response := map[string]interface{}{

internal/api/client.go

@@ -145,7 +145,7 @@ func handleAPIResponse(response *APIBaseResponse) (string, error) {
 	if response.State == "S" {
 		// Success - return encrypted payload for caller to decrypt
 		if response.Payload == "" {
-			return "", fmt.Errorf("payload not found in response")
+			return "", errors.New("payload not found in response")
 		}
 
 		return response.Payload, nil
@@ -168,10 +168,10 @@ func handleAPIResponse(response *APIBaseResponse) (string, error) {
 
 	// Generic error
 	if response.Message != "" {
-		return "", NewAPIError(fmt.Sprintf("Request failed: %s", response.Message))
+		return "", NewAPIError("Request failed: " + response.Message)
 	}
 	if response.Error != "" {
-		return "", NewAPIError(fmt.Sprintf("Request failed: %s", response.Error))
+		return "", NewAPIError("Request failed: " + response.Error)
 	}
 
 	return "", NewAPIError("Request failed for an unknown reason")

internal/api/client_test.go

@@ -19,11 +19,11 @@ func TestAPIRequest_Success(t *testing.T) {
 	// Create a mock server
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Verify headers
-		assert.NotEmpty(t, r.Header.Get("device-id"), "device-id header is missing")
-		assert.NotEmpty(t, r.Header.Get("app-code"), "app-code header is missing")
-		assert.Equal(t, UserAgentBaseAPI, r.Header.Get("user-agent"))
-		assert.NotEmpty(t, r.Header.Get("sign"), "sign header is missing")
-		assert.NotEmpty(t, r.Header.Get("timestamp"), "timestamp header is missing")
+		assert.NotEmpty(t, r.Header.Get("Device-Id"), "device-id header is missing")
+		assert.NotEmpty(t, r.Header.Get("App-Code"), "app-code header is missing")
+		assert.Equal(t, UserAgentBaseAPI, r.Header.Get("User-Agent"))
+		assert.NotEmpty(t, r.Header.Get("Sign"), "sign header is missing")
+		assert.NotEmpty(t, r.Header.Get("Timestamp"), "timestamp header is missing")
 
 		// Return success response with encrypted payload
 		// Encrypt a simple JSON response
@@ -249,7 +249,7 @@ func TestAPIRequest_POST_WithBody(t *testing.T) {
 		assert.Equalf(t, "POST", r.Method, "Expected POST method, got %s", r.Method)
 
 		// Verify sign header is present
-		assert.NotEmpty(t, r.Header.Get("sign"), "sign header is missing")
+		assert.NotEmpty(t, r.Header.Get("Sign"), "sign header is missing")
 
 		// Return encrypted success response
 		testResponse := map[string]interface{}{

internal/api/crypto.go

@@ -8,6 +8,7 @@ import (
 	"crypto/x509"
 	"encoding/base64"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -50,7 +51,7 @@ func EncryptRSA(data, publicKeyBase64 string) ([]byte, error) {
 
 	rsaPubKey, ok := pubKey.(*rsa.PublicKey)
 	if !ok {
-		return nil, fmt.Errorf("not an RSA public key")
+		return nil, errors.New("not an RSA public key")
 	}
 
 	// Encrypt using PKCS1v15

internal/api/types.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strings"
 )
@@ -224,15 +225,15 @@ type RemoteHvacInfo struct {
 // GetInternalVIN extracts the internal VIN from the first vehicle in the response
 func (r *VecBaseInfosResponse) GetInternalVIN() (string, error) {
 	if len(r.VecBaseInfos) == 0 {
-		return "", fmt.Errorf("no vehicles found")
+		return "", errors.New("no vehicles found")
 	}
 	return string(r.VecBaseInfos[0].Vehicle.CvInformation.InternalVIN), nil
 }
 
 // GetVehicleInfo extracts vehicle identification info from the response
 func (r *VecBaseInfosResponse) GetVehicleInfo() (vin, nickname, modelName, modelYear string, err error) {
 	if len(r.VecBaseInfos) == 0 {
-		err = fmt.Errorf("no vehicles found")
+		err = errors.New("no vehicles found")
 		return
 	}
 	info := r.VecBaseInfos[0]
@@ -247,7 +248,7 @@ func (r *VecBaseInfosResponse) GetVehicleInfo() (vin, nickname, modelName, model
 // GetBatteryInfo extracts battery information from the EV status response
 func (r *EVVehicleStatusResponse) GetBatteryInfo() (BatteryInfo, error) {
 	if len(r.ResultData) == 0 {
-		return BatteryInfo{}, fmt.Errorf("no EV status data available")
+		return BatteryInfo{}, errors.New("no EV status data available")
 	}
 	chargeInfo := r.ResultData[0].PlusBInformation.VehicleInfo.ChargeInfo
 	return BatteryInfo{
@@ -265,11 +266,11 @@ func (r *EVVehicleStatusResponse) GetBatteryInfo() (BatteryInfo, error) {
 // GetHvacInfo extracts HVAC information from the EV status response
 func (r *EVVehicleStatusResponse) GetHvacInfo() (HVACInfo, error) {
 	if len(r.ResultData) == 0 {
-		return HVACInfo{}, fmt.Errorf("no EV status data available")
+		return HVACInfo{}, errors.New("no EV status data available")
 	}
 	hvacInfo := r.ResultData[0].PlusBInformation.VehicleInfo.RemoteHvacInfo
 	if hvacInfo == nil {
-		return HVACInfo{}, fmt.Errorf("no HVAC info available")
+		return HVACInfo{}, errors.New("no HVAC info available")
 	}
 	return HVACInfo{
 		HVACOn:         int(hvacInfo.HVAC) == HVACStatusOn,
@@ -283,15 +284,15 @@ func (r *EVVehicleStatusResponse) GetHvacInfo() (HVACInfo, error) {
 // GetOccurrenceDate returns the occurrence date from the first result
 func (r *EVVehicleStatusResponse) GetOccurrenceDate() (string, error) {
 	if len(r.ResultData) == 0 {
-		return "", fmt.Errorf("no EV status data available")
+		return "", errors.New("no EV status data available")
 	}
 	return r.ResultData[0].OccurrenceDate, nil
 }
 
 // GetFuelInfo extracts fuel information from the vehicle status response
 func (r *VehicleStatusResponse) GetFuelInfo() (FuelInfo, error) {
 	if len(r.RemoteInfos) == 0 {
-		return FuelInfo{}, fmt.Errorf("no vehicle status data available")
+		return FuelInfo{}, errors.New("no vehicle status data available")
 	}
 	fuel := r.RemoteInfos[0].ResidualFuel
 	return FuelInfo{
@@ -303,7 +304,7 @@ func (r *VehicleStatusResponse) GetFuelInfo() (FuelInfo, error) {
 // GetTiresInfo extracts tire pressure information from the vehicle status response
 func (r *VehicleStatusResponse) GetTiresInfo() (TireInfo, error) {
 	if len(r.RemoteInfos) == 0 {
-		return TireInfo{}, fmt.Errorf("no vehicle status data available")
+		return TireInfo{}, errors.New("no vehicle status data available")
 	}
 	tpms := r.RemoteInfos[0].TPMSInformation
 	return TireInfo{
@@ -317,7 +318,7 @@ func (r *VehicleStatusResponse) GetTiresInfo() (TireInfo, error) {
 // GetLocationInfo extracts location information from the vehicle status response
 func (r *VehicleStatusResponse) GetLocationInfo() (LocationInfo, error) {
 	if len(r.AlertInfos) == 0 {
-		return LocationInfo{}, fmt.Errorf("no alert info available")
+		return LocationInfo{}, errors.New("no alert info available")
 	}
 	pos := r.AlertInfos[0].PositionInfo
 	return LocationInfo{
@@ -401,7 +402,7 @@ type HVACInfo struct {
 // GetDoorsInfo extracts door lock status from the vehicle status response
 func (r *VehicleStatusResponse) GetDoorsInfo() (status DoorStatus, err error) {
 	if len(r.AlertInfos) == 0 {
-		err = fmt.Errorf("no alert info available")
+		err = errors.New("no alert info available")
 		return
 	}
 	door := r.AlertInfos[0].Door
@@ -434,7 +435,7 @@ func (r *VehicleStatusResponse) GetDoorsInfo() (status DoorStatus, err error) {
 // GetOdometerInfo extracts odometer reading from the vehicle status response
 func (r *VehicleStatusResponse) GetOdometerInfo() (OdometerInfo, error) {
 	if len(r.RemoteInfos) == 0 {
-		return OdometerInfo{}, fmt.Errorf("no vehicle status data available")
+		return OdometerInfo{}, errors.New("no vehicle status data available")
 	}
 	return OdometerInfo{
 		OdometerKm: r.RemoteInfos[0].DriveInformation.OdoDispValue,
@@ -444,7 +445,7 @@ func (r *VehicleStatusResponse) GetOdometerInfo() (OdometerInfo, error) {
 // GetWindowsInfo extracts window position information from the vehicle status response
 func (r *VehicleStatusResponse) GetWindowsInfo() (WindowStatus, error) {
 	if len(r.AlertInfos) == 0 {
-		return WindowStatus{}, fmt.Errorf("no alert info available")
+		return WindowStatus{}, errors.New("no alert info available")
 	}
 	pw := r.AlertInfos[0].Pw
 	return WindowStatus{
@@ -458,7 +459,7 @@ func (r *VehicleStatusResponse) GetWindowsInfo() (WindowStatus, error) {
 // GetHazardInfo extracts hazard lights status from the vehicle status response
 func (r *VehicleStatusResponse) GetHazardInfo() (hazardsOn bool, err error) {
 	if len(r.AlertInfos) == 0 {
-		err = fmt.Errorf("no alert info available")
+		err = errors.New("no alert info available")
 		return
 	}
 	hazardsOn = int(r.AlertInfos[0].HazardLamp.HazardSw) == HazardLightsOn

internal/cli/client.go

@@ -28,13 +28,8 @@ func createAPIClient(ctx context.Context) (*api.Client, error) {
 		return nil, fmt.Errorf("failed to create API client: %w", err)
 	}
 
-	// Try to load cached credentials
-	cachedCreds, err := cache.Load()
-	if err != nil {
-		// If cache load fails, just continue without it
-		// The client will authenticate normally
-		return client, nil
-	}
+	// Try to load cached credentials (ignore errors - client will authenticate normally)
+	cachedCreds, _ := cache.Load()
 
 	// If we have valid cached credentials, use them
 	if cachedCreds != nil && cachedCreds.IsValid() {

internal/cli/skill_test.go

@@ -36,6 +36,7 @@ func TestUninstallSkill(t *testing.T) {
 		{
 			name: "removes existing directory",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				// Create the directory structure
 				skillPath := filepath.Join(tempDir, ".claude", "skills", skill.SkillName)
 				err := os.MkdirAll(skillPath, 0755)
@@ -45,13 +46,13 @@ func TestUninstallSkill(t *testing.T) {
 				testFile := filepath.Join(skillPath, "test.txt")
 				err = os.WriteFile(testFile, []byte("test"), 0644)
 				require.NoError(t, err, "Failed to create test file: %v")
-
 			},
 			wantErr: false,
 		},
 		{
 			name: "handles non-existent directory gracefully",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				// Don't create anything - directory doesn't exist
 			},
 			wantErr: false,
@@ -218,20 +219,21 @@ func TestSkillUninstallCommand_Execute(t *testing.T) {
 		{
 			name: "removes existing installation",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				skillPath := filepath.Join(tempDir, ".claude", "skills", skill.SkillName)
 				err := os.MkdirAll(skillPath, 0755)
 				require.NoError(t, err, "Failed to create skill directory: %v")
 
 				testFile := filepath.Join(skillPath, "test.txt")
 				err = os.WriteFile(testFile, []byte("test"), 0644)
 				require.NoError(t, err, "Failed to create test file: %v")
-
 			},
 			expectedOutput: "Skill uninstalled from ",
 		},
 		{
 			name: "handles non-existent installation",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				// Don't create anything
 			},
 			expectedOutput: "Skill not installed at ",
@@ -395,6 +397,7 @@ func TestCheckSkillVersion(t *testing.T) {
 		{
 			name: "returns SkillNotInstalled when skill directory does not exist",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				// Don't create anything
 			},
 			expectedStatus:  SkillNotInstalled,
@@ -403,6 +406,7 @@ func TestCheckSkillVersion(t *testing.T) {
 		{
 			name: "returns SkillVersionUnknown when skill exists without version file",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				skillPath := filepath.Join(tempDir, ".claude", "skills", skill.SkillName)
 				err := os.MkdirAll(skillPath, 0755)
 				require.NoError(t, err, "Failed to create skill directory: %v")
@@ -418,36 +422,37 @@ func TestCheckSkillVersion(t *testing.T) {
 		{
 			name: "returns SkillVersionMatch when versions match",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				skillPath := filepath.Join(tempDir, ".claude", "skills", skill.SkillName)
 				err := os.MkdirAll(skillPath, 0755)
 				require.NoError(t, err, "Failed to create skill directory: %v")
 
 				versionPath := filepath.Join(skillPath, ".mcs-version")
 				err = os.WriteFile(versionPath, []byte(Version), 0644)
 				require.NoError(t, err, "Failed to create version file: %v")
-
 			},
 			expectedStatus:  SkillVersionMatch,
 			expectedVersion: Version,
 		},
 		{
 			name: "returns SkillVersionMismatch when versions differ",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				skillPath := filepath.Join(tempDir, ".claude", "skills", skill.SkillName)
 				err := os.MkdirAll(skillPath, 0755)
 				require.NoError(t, err, "Failed to create skill directory: %v")
 
 				versionPath := filepath.Join(skillPath, ".mcs-version")
 				err = os.WriteFile(versionPath, []byte("1.0.0"), 0644)
 				require.NoError(t, err, "Failed to create version file: %v")
-
 			},
 			expectedStatus:  SkillVersionMismatch,
 			expectedVersion: "1.0.0",
 		},
 		{
 			name: "handles version file with whitespace",
 			setupFunc: func(t *testing.T, tempDir string) {
+				t.Helper()
 				skillPath := filepath.Join(tempDir, ".claude", "skills", skill.SkillName)
 				err := os.MkdirAll(skillPath, 0755)
 				require.NoError(t, err, "Failed to create skill directory: %v")
@@ -456,7 +461,6 @@ func TestCheckSkillVersion(t *testing.T) {
 				// Write version with trailing newline
 				err = os.WriteFile(versionPath, []byte(Version+"\n"), 0644)
 				require.NoError(t, err, "Failed to create version file: %v")
-
 			},
 			expectedStatus:  SkillVersionMatch,
 			expectedVersion: Version,