fix: resolve nlreturn, modernize, perfsprint, wsl_v5, and partial err113 lint issues

internal/db/db.go

@@ -90,6 +90,7 @@ func NewTest(dsn string) (*Database, error) {
 	// Item 9: Enable foreign keys
 	if _, err := d.Exec("PRAGMA foreign_keys = ON"); err != nil {
 		_ = d.Close()
+
 		return nil, fmt.Errorf("enable foreign keys: %w", err)
 	}
 
@@ -219,6 +220,7 @@ func (s *Database) DeleteAuthToken(
 	_, err := s.db.ExecContext(ctx,
 		`DELETE FROM auth_tokens WHERE token = ?`, token,
 	)
+
 	return err
 }
 
@@ -231,6 +233,7 @@ func (s *Database) UpdateUserLastSeen(
 		`UPDATE users SET last_seen_at = CURRENT_TIMESTAMP WHERE id = ?`,
 		userID,
 	)
+
 	return err
 }
 
@@ -394,6 +397,7 @@ func (s *Database) DequeueMessages(
 	if err != nil {
 		return nil, err
 	}
+
 	defer func() { _ = rows.Close() }()
 
 	entries := []*models.MessageQueueEntry{}
@@ -423,7 +427,7 @@ func (s *Database) AckMessages(
 	}
 
 	placeholders := make([]string, len(entryIDs))
-	args := make([]interface{}, len(entryIDs))
+	args := make([]any, len(entryIDs))
 
 	for i, id := range entryIDs {
 		placeholders[i] = "?"

internal/db/queries.go

@@ -62,7 +62,8 @@ func (s *Database) ListChannels(ctx context.Context, userID string) ([]ChannelIn
 
 	for rows.Next() {
 		var ch ChannelInfo
-		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic); err != nil {
+		err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic)
+		if err != nil {
 			return nil, err
 		}
 
@@ -95,7 +96,8 @@ func (s *Database) ChannelMembers(ctx context.Context, channelID string) ([]Memb
 
 	for rows.Next() {
 		var m MemberInfo
-		if err := rows.Scan(&m.ID, &m.Nick, &m.LastSeen); err != nil {
+		err := rows.Scan(&m.ID, &m.Nick, &m.LastSeen)
+		if err != nil {
 			return nil, err
 		}
 
@@ -182,7 +184,8 @@ func (s *Database) PollMessages(ctx context.Context, userID string, afterTS stri
 
 	for rows.Next() {
 		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt); err != nil {
+		err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt)
+		if err != nil {
 			return nil, err
 		}
 
@@ -200,7 +203,7 @@ func (s *Database) GetMessagesBefore(ctx context.Context, target string, beforeT
 
 	var rows interface {
 		Next() bool
-		Scan(dest ...interface{}) error
+		Scan(dest ...any) error
 		Close() error
 		Err() error
 	}
@@ -233,7 +236,8 @@ func (s *Database) GetMessagesBefore(ctx context.Context, target string, beforeT
 
 	for rows.Next() {
 		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt); err != nil {
+		err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt)
+		if err != nil {
 			return nil, err
 		}
 
@@ -256,7 +260,7 @@ func (s *Database) GetDMsBefore(ctx context.Context, userA, userB string, before
 
 	var rows interface {
 		Next() bool
-		Scan(dest ...interface{}) error
+		Scan(dest ...any) error
 		Close() error
 		Err() error
 	}
@@ -290,7 +294,8 @@ func (s *Database) GetDMsBefore(ctx context.Context, userA, userB string, before
 
 	for rows.Next() {
 		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Nick, &m.Content, &m.DMTarget, &m.CreatedAt); err != nil {
+		err := rows.Scan(&m.ID, &m.Nick, &m.Content, &m.DMTarget, &m.CreatedAt)
+		if err != nil {
 			return nil, err
 		}
 
@@ -341,7 +346,8 @@ func (s *Database) ListAllChannels(ctx context.Context) ([]ChannelInfo, error) {
 
 	for rows.Next() {
 		var ch ChannelInfo
-		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic); err != nil {
+		err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic)
+		if err != nil {
 			return nil, err
 		}
 

internal/handlers/api.go

@@ -34,6 +34,7 @@ func (s *Handlers) requireAuth(w http.ResponseWriter, r *http.Request) (string,
 	uid, nick, err := s.authUser(r)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "unauthorized"}, http.StatusUnauthorized)
+
 		return "", "", false
 	}
 
@@ -52,6 +53,7 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 	type request struct {
 		Nick string `json:"nick"`
 	}
+
 	type response struct {
 		ID    string `json:"id"`
 		Nick  string `json:"nick"`
@@ -62,12 +64,14 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 		var req request
 		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
 			s.respondJSON(w, r, map[string]string{"error": "invalid request"}, http.StatusBadRequest)
+
 			return
 		}
 
 		req.Nick = strings.TrimSpace(req.Nick)
 		if req.Nick == "" || len(req.Nick) > 32 {
 			s.respondJSON(w, r, map[string]string{"error": "nick must be 1-32 characters"}, http.StatusBadRequest)
+
 			return
 		}
 
@@ -77,6 +81,7 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 		if err != nil {
 			if strings.Contains(err.Error(), "UNIQUE") {
 				s.respondJSON(w, r, map[string]string{"error": "nick already taken"}, http.StatusConflict)
+
 				return
 			}
 
@@ -162,6 +167,7 @@ func (s *Handlers) HandleChannelMembers() http.HandlerFunc {
 			"SELECT id FROM channels WHERE name = ?", name).Scan(&chID)
 		if err != nil {
 			s.respondJSON(w, r, map[string]string{"error": "channel not found"}, http.StatusNotFound)
+
 			return
 		}
 
@@ -205,10 +211,10 @@ func (s *Handlers) HandleGetMessages() http.HandlerFunc {
 // The "command" field dispatches to the appropriate logic.
 func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 	type request struct {
-		Command string      `json:"command"`
-		To      string      `json:"to"`
-		Params  []string    `json:"params,omitempty"`
-		Body    interface{} `json:"body,omitempty"`
+		Command string   `json:"command"`
+		To      string   `json:"to"`
+		Params  []string `json:"params,omitempty"`
+		Body    any      `json:"body,omitempty"`
 	}
 
 	return func(w http.ResponseWriter, r *http.Request) {
@@ -218,8 +224,10 @@ func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 		}
 
 		var req request
-		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		err := json.NewDecoder(r.Body).Decode(&req)
+		if err != nil {
 			s.respondJSON(w, r, map[string]string{"error": "invalid request"}, http.StatusBadRequest)
+
 			return
 		}
 
@@ -229,7 +237,7 @@ func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 		// Helper to extract body as string lines.
 		bodyLines := func() []string {
 			switch v := req.Body.(type) {
-			case []interface{}:
+			case []any:
 				lines := make([]string, 0, len(v))
 
 				for _, item := range v {
@@ -267,6 +275,7 @@ func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 
 		default:
 			_ = nick // suppress unused warning
+
 			s.respondJSON(w, r, map[string]string{"error": "unknown command: " + req.Command}, http.StatusBadRequest)
 		}
 	}
@@ -275,11 +284,13 @@ func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 func (s *Handlers) handlePrivmsg(w http.ResponseWriter, r *http.Request, uid, nick, to string, lines []string) {
 	if to == "" {
 		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
 		return
 	}
 
 	if len(lines) == 0 {
 		s.respondJSON(w, r, map[string]string{"error": "body required"}, http.StatusBadRequest)
+
 		return
 	}
 
@@ -293,6 +304,7 @@ func (s *Handlers) handlePrivmsg(w http.ResponseWriter, r *http.Request, uid, ni
 			"SELECT id FROM channels WHERE name = ?", to).Scan(&chID)
 		if err != nil {
 			s.respondJSON(w, r, map[string]string{"error": "channel not found"}, http.StatusNotFound)
+
 			return
 		}
 
@@ -310,6 +322,7 @@ func (s *Handlers) handlePrivmsg(w http.ResponseWriter, r *http.Request, uid, ni
 		targetUser, err := s.params.Database.GetUserByNick(r.Context(), to)
 		if err != nil {
 			s.respondJSON(w, r, map[string]string{"error": "user not found"}, http.StatusNotFound)
+
 			return
 		}
 
@@ -328,6 +341,7 @@ func (s *Handlers) handlePrivmsg(w http.ResponseWriter, r *http.Request, uid, ni
 func (s *Handlers) handleJoin(w http.ResponseWriter, r *http.Request, uid, to string) {
 	if to == "" {
 		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
 		return
 	}
 
@@ -357,6 +371,7 @@ func (s *Handlers) handleJoin(w http.ResponseWriter, r *http.Request, uid, to st
 func (s *Handlers) handlePart(w http.ResponseWriter, r *http.Request, uid, to string) {
 	if to == "" {
 		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
 		return
 	}
 
@@ -371,6 +386,7 @@ func (s *Handlers) handlePart(w http.ResponseWriter, r *http.Request, uid, to st
 		"SELECT id FROM channels WHERE name = ?", channel).Scan(&chID)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "channel not found"}, http.StatusNotFound)
+
 		return
 	}
 
@@ -387,18 +403,22 @@ func (s *Handlers) handlePart(w http.ResponseWriter, r *http.Request, uid, to st
 func (s *Handlers) handleNick(w http.ResponseWriter, r *http.Request, uid string, lines []string) {
 	if len(lines) == 0 {
 		s.respondJSON(w, r, map[string]string{"error": "body required (new nick)"}, http.StatusBadRequest)
+
 		return
 	}
 
 	newNick := strings.TrimSpace(lines[0])
 	if newNick == "" || len(newNick) > 32 {
 		s.respondJSON(w, r, map[string]string{"error": "nick must be 1-32 characters"}, http.StatusBadRequest)
+
 		return
 	}
 
-	if err := s.params.Database.ChangeNick(r.Context(), uid, newNick); err != nil {
+	err := s.params.Database.ChangeNick(r.Context(), uid, newNick)
+	if err != nil {
 		if strings.Contains(err.Error(), "UNIQUE") {
 			s.respondJSON(w, r, map[string]string{"error": "nick already in use"}, http.StatusConflict)
+
 			return
 		}
 
@@ -414,11 +434,13 @@ func (s *Handlers) handleNick(w http.ResponseWriter, r *http.Request, uid string
 func (s *Handlers) handleTopic(w http.ResponseWriter, r *http.Request, uid, to string, lines []string) {
 	if to == "" {
 		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
 		return
 	}
 
 	if len(lines) == 0 {
 		s.respondJSON(w, r, map[string]string{"error": "body required (topic text)"}, http.StatusBadRequest)
+
 		return
 	}
 
@@ -429,7 +451,8 @@ func (s *Handlers) handleTopic(w http.ResponseWriter, r *http.Request, uid, to s
 		channel = "#" + channel
 	}
 
-	if err := s.params.Database.SetTopic(r.Context(), channel, uid, topic); err != nil {
+	err := s.params.Database.SetTopic(r.Context(), channel, uid, topic)
+	if err != nil {
 		s.log.Error("set topic failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
 
@@ -450,6 +473,7 @@ func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 		target := r.URL.Query().Get("target")
 		if target == "" {
 			s.respondJSON(w, r, map[string]string{"error": "target required"}, http.StatusBadRequest)
+
 			return
 		}
 
@@ -468,6 +492,7 @@ func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 				"SELECT id FROM channels WHERE name = ?", target).Scan(&chID)
 			if err != nil {
 				s.respondJSON(w, r, map[string]string{"error": "channel not found"}, http.StatusNotFound)
+
 				return
 			}
 
@@ -485,6 +510,7 @@ func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 			targetUser, err := s.params.Database.GetUserByNick(r.Context(), target)
 			if err != nil {
 				s.respondJSON(w, r, map[string]string{"error": "user not found"}, http.StatusNotFound)
+
 				return
 			}
 

internal/models/auth_token.go

@@ -2,7 +2,7 @@ package models
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"time"
 )
 
@@ -23,5 +23,5 @@ func (t *AuthToken) User(ctx context.Context) (*User, error) {
 		return ul.GetUserByID(ctx, t.UserID)
 	}
 
-	return nil, fmt.Errorf("user lookup not available")
+	return nil, errors.New("user lookup not available")
 }

internal/models/channel_member.go

@@ -2,7 +2,7 @@ package models
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"time"
 )
 
@@ -23,7 +23,7 @@ func (cm *ChannelMember) User(ctx context.Context) (*User, error) {
 		return ul.GetUserByID(ctx, cm.UserID)
 	}
 
-	return nil, fmt.Errorf("user lookup not available")
+	return nil, errors.New("user lookup not available")
 }
 
 // Channel returns the full Channel for this membership.
@@ -32,5 +32,5 @@ func (cm *ChannelMember) Channel(ctx context.Context) (*Channel, error) {
 		return cl.GetChannelByID(ctx, cm.ChannelID)
 	}
 
-	return nil, fmt.Errorf("channel lookup not available")
+	return nil, errors.New("channel lookup not available")
 }

internal/models/session.go

@@ -2,7 +2,7 @@ package models
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"time"
 )
 
@@ -23,5 +23,5 @@ func (s *Session) User(ctx context.Context) (*User, error) {
 		return ul.GetUserByID(ctx, s.UserID)
 	}
 
-	return nil, fmt.Errorf("user lookup not available")
+	return nil, errors.New("user lookup not available")
 }

internal/server/routes.go

@@ -71,16 +71,20 @@ func (s *Server) SetupRoutes() {
 		s.log.Error("failed to get web dist filesystem", "error", err)
 	} else {
 		fileServer := http.FileServer(http.FS(distFS))
+
 		s.router.Get("/*", func(w http.ResponseWriter, r *http.Request) {
 			// Try to serve the file; if not found, serve index.html for SPA routing
 			f, err := distFS.(fs.ReadFileFS).ReadFile(r.URL.Path[1:])
 			if err != nil || len(f) == 0 {
 				indexHTML, _ := distFS.(fs.ReadFileFS).ReadFile("index.html")
+
 				w.Header().Set("Content-Type", "text/html; charset=utf-8")
 				w.WriteHeader(http.StatusOK)
 				_, _ = w.Write(indexHTML)
+
 				return
 			}
+
 			fileServer.ServeHTTP(w, r)
 		})
 	}