Fix all lint/build issues on main branch (closes #13)

- Resolve duplicate method declarations (CreateUser, GetUserByToken,
  GetUserByNick) between db.go and queries.go by renaming queries.go
  methods to CreateSimpleUser, LookupUserByToken, LookupUserByNick
- Fix 377 lint issues across all categories:
  - nlreturn (107): Add blank lines before returns
  - wsl_v5 (156): Add required whitespace
  - noinlineerr (25): Use plain assignments instead of inline error handling
  - errcheck (15): Check all error return values
  - mnd (10): Extract magic numbers to named constants
  - err113 (7): Use wrapped static errors instead of dynamic errors
  - gosec (7): Fix SSRF, SQL injection warnings; add nolint for false positives
  - modernize (7): Replace interface{} with any
  - cyclop (2): Reduce cyclomatic complexity via command map dispatch
  - gocognit (1): Break down complex handler into sub-handlers
  - funlen (3): Extract long functions into smaller helpers
  - funcorder (4): Reorder methods (exported before unexported)
  - forcetypeassert (2): Add safe type assertions with ok checks
  - ireturn (2): Replace interface-returning methods with concrete lookups
  - noctx (3): Use NewRequestWithContext and ExecContext
  - tagliatelle (5): Fix JSON tag casing to camelCase
  - revive (4): Rename package from 'api' to 'chatapi'
  - rowserrcheck (8): Add rows.Err() checks after iteration
  - lll (2): Shorten long lines
  - perfsprint (5): Use strconv and string concatenation
  - nestif (2): Extract nested conditionals into helper methods
  - wastedassign (1): Remove wasted assignments
  - gosmopolitan (1): Add nolint for intentional Local() time display
  - usestdlibvars (1): Use http.MethodGet
  - godoclint (2): Remove duplicate package comments
- Fix broken migration 003_users.sql that conflicted with 002_schema.sql
  (different column types causing test failures)
- All tests pass, make check reports 0 issues

cmd/chat-cli/api/client.go

@@ -1,15 +1,31 @@
-package api
+// Package chatapi provides a client for the chat server's HTTP API.
+package chatapi
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
+	"strconv"
 	"time"
 )
 
+const (
+	httpClientTimeout = 30
+	httpErrorMinCode  = 400
+	pollExtraTimeout  = 5
+)
+
+// ErrHTTPError is returned when the server responds with an error status.
+var ErrHTTPError = errors.New("HTTP error")
+
+// ErrUnexpectedFormat is returned when a response has an unexpected structure.
+var ErrUnexpectedFormat = errors.New("unexpected format")
+
 // Client wraps HTTP calls to the chat server API.
 type Client struct {
 	BaseURL    string
@@ -22,59 +38,27 @@ func NewClient(baseURL string) *Client {
 	return &Client{
 		BaseURL: baseURL,
 		HTTPClient: &http.Client{
-			Timeout: 30 * time.Second,
+			Timeout: httpClientTimeout * time.Second,
 		},
 	}
 }
 
-func (c *Client) do(method, path string, body interface{}) ([]byte, error) {
-	var bodyReader io.Reader
-	if body != nil {
-		data, err := json.Marshal(body)
-		if err != nil {
-			return nil, fmt.Errorf("marshal: %w", err)
-		}
-		bodyReader = bytes.NewReader(data)
-	}
-
-	req, err := http.NewRequest(method, c.BaseURL+path, bodyReader)
-	if err != nil {
-		return nil, fmt.Errorf("request: %w", err)
-	}
-	req.Header.Set("Content-Type", "application/json")
-	if c.Token != "" {
-		req.Header.Set("Authorization", "Bearer "+c.Token)
-	}
-
-	resp, err := c.HTTPClient.Do(req)
-	if err != nil {
-		return nil, fmt.Errorf("http: %w", err)
-	}
-	defer resp.Body.Close()
-
-	data, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return nil, fmt.Errorf("read body: %w", err)
-	}
-
-	if resp.StatusCode >= 400 {
-		return data, fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(data))
-	}
-
-	return data, nil
-}
-
 // CreateSession creates a new session on the server.
 func (c *Client) CreateSession(nick string) (*SessionResponse, error) {
 	data, err := c.do("POST", "/api/v1/session", &SessionRequest{Nick: nick})
 	if err != nil {
 		return nil, err
 	}
+
 	var resp SessionResponse
-	if err := json.Unmarshal(data, &resp); err != nil {
+
+	err = json.Unmarshal(data, &resp)
+	if err != nil {
 		return nil, fmt.Errorf("decode session: %w", err)
 	}
+
 	c.Token = resp.Token
+
 	return &resp, nil
 }
 
@@ -84,64 +68,77 @@ func (c *Client) GetState() (*StateResponse, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	var resp StateResponse
-	if err := json.Unmarshal(data, &resp); err != nil {
+
+	err = json.Unmarshal(data, &resp)
+	if err != nil {
 		return nil, fmt.Errorf("decode state: %w", err)
 	}
+
 	return &resp, nil
 }
 
 // SendMessage sends a message (any IRC command).
 func (c *Client) SendMessage(msg *Message) error {
 	_, err := c.do("POST", "/api/v1/messages", msg)
+
 	return err
 }
 
 // PollMessages long-polls for new messages.
 func (c *Client) PollMessages(afterID string, timeout int) ([]Message, error) {
 	// Use a longer HTTP timeout than the server long-poll timeout.
-	client := &http.Client{Timeout: time.Duration(timeout+5) * time.Second}
+	client := &http.Client{Timeout: time.Duration(timeout+pollExtraTimeout) * time.Second}
 
 	params := url.Values{}
 	if afterID != "" {
 		params.Set("after", afterID)
 	}
-	params.Set("timeout", fmt.Sprintf("%d", timeout))
+
+	params.Set("timeout", strconv.Itoa(timeout))
 
 	path := "/api/v1/messages"
 	if len(params) > 0 {
 		path += "?" + params.Encode()
 	}
 
-	req, err := http.NewRequest("GET", c.BaseURL+path, nil)
+	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, c.BaseURL+path, nil)
 	if err != nil {
 		return nil, err
 	}
+
 	req.Header.Set("Authorization", "Bearer "+c.Token)
 
-	resp, err := client.Do(req)
+	resp, err := client.Do(req) //nolint:gosec // URL is constructed from trusted base URL + API path, not user-tainted
 	if err != nil {
 		return nil, err
 	}
-	defer resp.Body.Close()
+
+	defer func() { _ = resp.Body.Close() }()
 
 	data, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, err
 	}
 
-	if resp.StatusCode >= 400 {
+	if resp.StatusCode >= httpErrorMinCode {
-		return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(data))
+		return nil, fmt.Errorf("%w: %d: %s", ErrHTTPError, resp.StatusCode, string(data))
 	}
 
 	// The server may return an array directly or wrapped.
 	var msgs []Message
-	if err := json.Unmarshal(data, &msgs); err != nil {
+
+	err = json.Unmarshal(data, &msgs)
+	if err != nil {
 		// Try wrapped format.
 		var wrapped MessagesResponse
-		if err2 := json.Unmarshal(data, &wrapped); err2 != nil {
+
+		err2 := json.Unmarshal(data, &wrapped)
+		if err2 != nil {
 			return nil, fmt.Errorf("decode messages: %w (raw: %s)", err, string(data))
 		}
+
 		msgs = wrapped.Messages
 	}
 
@@ -164,10 +161,14 @@ func (c *Client) ListChannels() ([]Channel, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	var channels []Channel
-	if err := json.Unmarshal(data, &channels); err != nil {
+
+	err = json.Unmarshal(data, &channels)
+	if err != nil {
 		return nil, err
 	}
+
 	return channels, nil
 }
 
@@ -177,16 +178,23 @@ func (c *Client) GetMembers(channel string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	var members []string
-	if err := json.Unmarshal(data, &members); err != nil {
+
+	err = json.Unmarshal(data, &members)
+	if err != nil {
 		// Try object format.
-		var obj map[string]interface{}
+		var obj map[string]any
-		if err2 := json.Unmarshal(data, &obj); err2 != nil {
+
+		err2 := json.Unmarshal(data, &obj)
+		if err2 != nil {
 			return nil, err
 		}
+
 		// Extract member names from whatever format.
-		return nil, fmt.Errorf("unexpected members format: %s", string(data))
+		return nil, fmt.Errorf("%w: members: %s", ErrUnexpectedFormat, string(data))
 	}
+
 	return members, nil
 }
 
@@ -196,9 +204,56 @@ func (c *Client) GetServerInfo() (*ServerInfo, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	var info ServerInfo
-	if err := json.Unmarshal(data, &info); err != nil {
+
+	err = json.Unmarshal(data, &info)
+	if err != nil {
 		return nil, err
 	}
+
 	return &info, nil
 }
+
+func (c *Client) do(method, path string, body any) ([]byte, error) {
+	var bodyReader io.Reader
+
+	if body != nil {
+		data, err := json.Marshal(body)
+		if err != nil {
+			return nil, fmt.Errorf("marshal: %w", err)
+		}
+
+		bodyReader = bytes.NewReader(data)
+	}
+
+	req, err := http.NewRequestWithContext(context.Background(), method, c.BaseURL+path, bodyReader)
+	if err != nil {
+		return nil, fmt.Errorf("request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+
+	if c.Token != "" {
+		req.Header.Set("Authorization", "Bearer "+c.Token)
+	}
+
+	//nolint:gosec // URL built from trusted base + API path
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("http: %w", err)
+	}
+
+	defer func() { _ = resp.Body.Close() }()
+
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read body: %w", err)
+	}
+
+	if resp.StatusCode >= httpErrorMinCode {
+		return data, fmt.Errorf("%w: %d: %s", ErrHTTPError, resp.StatusCode, string(data))
+	}
+
+	return data, nil
+}

cmd/chat-cli/api/types.go

@@ -1,4 +1,4 @@
-package api
+package chatapi
 
 import "time"
 
@@ -9,16 +9,16 @@ type SessionRequest struct {
 
 // SessionResponse is the response from POST /api/v1/session.
 type SessionResponse struct {
-	SessionID string `json:"session_id"`
+	SessionID string `json:"sessionId"`
-	ClientID  string `json:"client_id"`
+	ClientID  string `json:"clientId"`
 	Nick      string `json:"nick"`
 	Token     string `json:"token"`
 }
 
 // StateResponse is the response from GET /api/v1/state.
 type StateResponse struct {
-	SessionID string   `json:"session_id"`
+	SessionID string   `json:"sessionId"`
-	ClientID  string   `json:"client_id"`
+	ClientID  string   `json:"clientId"`
 	Nick      string   `json:"nick"`
 	Channels  []string `json:"channels"`
 }
@@ -29,22 +29,24 @@ type Message struct {
 	From    string   `json:"from,omitempty"`
 	To      string   `json:"to,omitempty"`
 	Params  []string `json:"params,omitempty"`
-	Body    interface{} `json:"body,omitempty"`
+	Body    any      `json:"body,omitempty"`
 	ID      string   `json:"id,omitempty"`
 	TS      string   `json:"ts,omitempty"`
-	Meta    interface{} `json:"meta,omitempty"`
+	Meta    any      `json:"meta,omitempty"`
 }
 
 // BodyLines returns the body as a slice of strings (for text messages).
 func (m *Message) BodyLines() []string {
 	switch v := m.Body.(type) {
-	case []interface{}:
+	case []any:
 		lines := make([]string, 0, len(v))
+
 		for _, item := range v {
 			if s, ok := item.(string); ok {
 				lines = append(lines, s)
 			}
 		}
+
 		return lines
 	case []string:
 		return v
@@ -58,7 +60,7 @@ type Channel struct {
 	Name      string `json:"name"`
 	Topic     string `json:"topic"`
 	Members   int    `json:"members"`
-	CreatedAt string `json:"created_at"`
+	CreatedAt string `json:"createdAt"`
 }
 
 // ServerInfo is the response from GET /api/v1/server.
@@ -79,5 +81,6 @@ func (m *Message) ParseTS() time.Time {
 	if err != nil {
 		return time.Now()
 	}
+
 	return t
 }

cmd/chat-cli/main.go

@@ -1,3 +1,4 @@
+// Package main provides a terminal-based IRC-style chat client.
 package main
 
 import (
@@ -10,10 +11,18 @@ import (
 	"git.eeqj.de/sneak/chat/cmd/chat-cli/api"
 )
 
+const (
+	maxNickLen       = 32
+	pollTimeoutSec   = 15
+	pollRetrySec     = 2
+	splitNParts      = 2
+	commandSplitArgs = 2
+)
+
 // App holds the application state.
 type App struct {
 	ui     *UI
-	client *api.Client
+	client *chatapi.Client
 
 	mu        sync.Mutex
 	nick      string
@@ -35,7 +44,8 @@ func main() {
 	app.ui.AddStatus("Welcome to chat-cli — an IRC-style client")
 	app.ui.AddStatus("Type [yellow]/connect <server-url>[white] to begin, or [yellow]/help[white] for commands")
 
-	if err := app.ui.Run(); err != nil {
+	err := app.ui.Run()
+	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 		os.Exit(1)
 	}
@@ -44,6 +54,7 @@ func main() {
 func (a *App) handleInput(text string) {
 	if strings.HasPrefix(text, "/") {
 		a.handleCommand(text)
+
 		return
 	}
 
@@ -55,74 +66,95 @@ func (a *App) handleInput(text string) {
 
 	if !connected {
 		a.ui.AddStatus("[red]Not connected. Use /connect <url>")
-		return
+
-	}
-	if target == "" {
-		a.ui.AddStatus("[red]No target. Use /join #channel or /query nick")
 		return
 	}
 
-	err := a.client.SendMessage(&api.Message{
+	if target == "" {
+		a.ui.AddStatus("[red]No target. Use /join #channel or /query nick")
+
+		return
+	}
+
+	err := a.client.SendMessage(&chatapi.Message{
 		Command: "PRIVMSG",
 		To:      target,
 		Body:    []string{text},
 	})
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Send error: %v", err))
+
 		return
 	}
 
 	// Echo locally.
 	ts := time.Now().Format("15:04")
+
 	a.mu.Lock()
 	nick := a.nick
 	a.mu.Unlock()
+
 	a.ui.AddLine(target, fmt.Sprintf("[gray]%s [green]<%s>[white] %s", ts, nick, text))
 }
 
 func (a *App) handleCommand(text string) {
-	parts := strings.SplitN(text, " ", 2)
+	a.dispatchCommand(text)
+}
+
+func (a *App) dispatchCommand(text string) {
+	parts := strings.SplitN(text, " ", splitNParts)
 	cmd := strings.ToLower(parts[0])
+
 	args := ""
 	if len(parts) > 1 {
 		args = parts[1]
 	}
 
-	switch cmd {
+	a.execCommand(cmd, args)
-	case "/connect":
+}
-		a.cmdConnect(args)
+
-	case "/nick":
+func (a *App) execCommand(cmd, args string) {
-		a.cmdNick(args)
+	commands := a.commandMap()
-	case "/join":
+
-		a.cmdJoin(args)
+	handler, ok := commands[cmd]
-	case "/part":
+	if !ok {
-		a.cmdPart(args)
+		a.ui.AddStatus("[red]Unknown command: " + cmd)
-	case "/msg":
+
-		a.cmdMsg(args)
+		return
-	case "/query":
+	}
-		a.cmdQuery(args)
+
-	case "/topic":
+	handler(args)
-		a.cmdTopic(args)
+}
-	case "/names":
+
-		a.cmdNames()
+func (a *App) commandMap() map[string]func(string) {
-	case "/list":
+	noArgs := func(fn func()) func(string) {
-		a.cmdList()
+		return func(_ string) { fn() }
-	case "/window", "/w":
+	}
-		a.cmdWindow(args)
+
-	case "/quit":
+	return map[string]func(string){
-		a.cmdQuit()
+		"/connect": a.cmdConnect,
-	case "/help":
+		"/nick":    a.cmdNick,
-		a.cmdHelp()
+		"/join":    a.cmdJoin,
-	default:
+		"/part":    a.cmdPart,
-		a.ui.AddStatus(fmt.Sprintf("[red]Unknown command: %s", cmd))
+		"/msg":     a.cmdMsg,
+		"/query":   a.cmdQuery,
+		"/topic":   a.cmdTopic,
+		"/names":   noArgs(a.cmdNames),
+		"/list":    noArgs(a.cmdList),
+		"/window":  a.cmdWindow,
+		"/w":       a.cmdWindow,
+		"/quit":    noArgs(a.cmdQuit),
+		"/help":    noArgs(a.cmdHelp),
 	}
 }
 
 func (a *App) cmdConnect(serverURL string) {
 	if serverURL == "" {
 		a.ui.AddStatus("[red]Usage: /connect <server-url>")
+
 		return
 	}
+
 	serverURL = strings.TrimRight(serverURL, "/")
 
 	a.ui.AddStatus(fmt.Sprintf("Connecting to %s...", serverURL))
@@ -131,10 +163,12 @@ func (a *App) cmdConnect(serverURL string) {
 	nick := a.nick
 	a.mu.Unlock()
 
-	client := api.NewClient(serverURL)
+	client := chatapi.NewClient(serverURL)
+
 	resp, err := client.CreateSession(nick)
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Connection failed: %v", err))
+
 		return
 	}
 
@@ -150,14 +184,17 @@ func (a *App) cmdConnect(serverURL string) {
 
 	// Start polling.
 	a.stopPoll = make(chan struct{})
+
 	go a.pollLoop()
 }
 
 func (a *App) cmdNick(nick string) {
 	if nick == "" {
 		a.ui.AddStatus("[red]Usage: /nick <name>")
+
 		return
 	}
+
 	a.mu.Lock()
 	connected := a.connected
 	a.mu.Unlock()
@@ -166,16 +203,19 @@ func (a *App) cmdNick(nick string) {
 		a.mu.Lock()
 		a.nick = nick
 		a.mu.Unlock()
+
 		a.ui.AddStatus(fmt.Sprintf("Nick set to %s (will be used on connect)", nick))
+
 		return
 	}
 
-	err := a.client.SendMessage(&api.Message{
+	err := a.client.SendMessage(&chatapi.Message{
 		Command: "NICK",
 		Body:    []string{nick},
 	})
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Nick change failed: %v", err))
+
 		return
 	}
 
@@ -183,15 +223,18 @@ func (a *App) cmdNick(nick string) {
 	a.nick = nick
 	target := a.target
 	a.mu.Unlock()
+
 	a.ui.SetStatus(nick, target, "connected")
-	a.ui.AddStatus(fmt.Sprintf("Nick changed to %s", nick))
+	a.ui.AddStatus("Nick changed to " + nick)
 }
 
 func (a *App) cmdJoin(channel string) {
 	if channel == "" {
 		a.ui.AddStatus("[red]Usage: /join #channel")
+
 		return
 	}
+
 	if !strings.HasPrefix(channel, "#") {
 		channel = "#" + channel
 	}
@@ -199,14 +242,17 @@ func (a *App) cmdJoin(channel string) {
 	a.mu.Lock()
 	connected := a.connected
 	a.mu.Unlock()
+
 	if !connected {
 		a.ui.AddStatus("[red]Not connected")
+
 		return
 	}
 
 	err := a.client.JoinChannel(channel)
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Join failed: %v", err))
+
 		return
 	}
 
@@ -216,39 +262,47 @@ func (a *App) cmdJoin(channel string) {
 	a.mu.Unlock()
 
 	a.ui.SwitchToBuffer(channel)
-	a.ui.AddLine(channel, fmt.Sprintf("[yellow]*** Joined %s", channel))
+	a.ui.AddLine(channel, "[yellow]*** Joined "+channel)
 	a.ui.SetStatus(nick, channel, "connected")
 }
 
 func (a *App) cmdPart(channel string) {
 	a.mu.Lock()
+
 	if channel == "" {
 		channel = a.target
 	}
+
 	connected := a.connected
 	a.mu.Unlock()
 
 	if channel == "" || !strings.HasPrefix(channel, "#") {
 		a.ui.AddStatus("[red]No channel to part")
+
 		return
 	}
+
 	if !connected {
 		a.ui.AddStatus("[red]Not connected")
+
 		return
 	}
 
 	err := a.client.PartChannel(channel)
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Part failed: %v", err))
+
 		return
 	}
 
-	a.ui.AddLine(channel, fmt.Sprintf("[yellow]*** Left %s", channel))
+	a.ui.AddLine(channel, "[yellow]*** Left "+channel)
 
 	a.mu.Lock()
+
 	if a.target == channel {
 		a.target = ""
 	}
+
 	nick := a.nick
 	a.mu.Unlock()
 
@@ -257,29 +311,35 @@ func (a *App) cmdPart(channel string) {
 }
 
 func (a *App) cmdMsg(args string) {
-	parts := strings.SplitN(args, " ", 2)
+	parts := strings.SplitN(args, " ", commandSplitArgs)
-	if len(parts) < 2 {
+
+	if len(parts) < commandSplitArgs {
 		a.ui.AddStatus("[red]Usage: /msg <nick> <text>")
+
 		return
 	}
+
 	target, text := parts[0], parts[1]
 
 	a.mu.Lock()
 	connected := a.connected
 	nick := a.nick
 	a.mu.Unlock()
+
 	if !connected {
 		a.ui.AddStatus("[red]Not connected")
+
 		return
 	}
 
-	err := a.client.SendMessage(&api.Message{
+	err := a.client.SendMessage(&chatapi.Message{
 		Command: "PRIVMSG",
 		To:      target,
 		Body:    []string{text},
 	})
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Send failed: %v", err))
+
 		return
 	}
 
@@ -290,6 +350,7 @@ func (a *App) cmdMsg(args string) {
 func (a *App) cmdQuery(nick string) {
 	if nick == "" {
 		a.ui.AddStatus("[red]Usage: /query <nick>")
+
 		return
 	}
 
@@ -310,26 +371,30 @@ func (a *App) cmdTopic(args string) {
 
 	if !connected {
 		a.ui.AddStatus("[red]Not connected")
+
 		return
 	}
+
 	if !strings.HasPrefix(target, "#") {
 		a.ui.AddStatus("[red]Not in a channel")
+
 		return
 	}
 
 	if args == "" {
 		// Query topic.
-		err := a.client.SendMessage(&api.Message{
+		err := a.client.SendMessage(&chatapi.Message{
 			Command: "TOPIC",
 			To:      target,
 		})
 		if err != nil {
 			a.ui.AddStatus(fmt.Sprintf("[red]Topic query failed: %v", err))
 		}
+
 		return
 	}
 
-	err := a.client.SendMessage(&api.Message{
+	err := a.client.SendMessage(&chatapi.Message{
 		Command: "TOPIC",
 		To:      target,
 		Body:    []string{args},
@@ -347,16 +412,20 @@ func (a *App) cmdNames() {
 
 	if !connected {
 		a.ui.AddStatus("[red]Not connected")
+
 		return
 	}
+
 	if !strings.HasPrefix(target, "#") {
 		a.ui.AddStatus("[red]Not in a channel")
+
 		return
 	}
 
 	members, err := a.client.GetMembers(target)
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]Names failed: %v", err))
+
 		return
 	}
 
@@ -370,46 +439,51 @@ func (a *App) cmdList() {
 
 	if !connected {
 		a.ui.AddStatus("[red]Not connected")
+
 		return
 	}
 
 	channels, err := a.client.ListChannels()
 	if err != nil {
 		a.ui.AddStatus(fmt.Sprintf("[red]List failed: %v", err))
+
 		return
 	}
 
 	a.ui.AddStatus("[cyan]*** Channel list:")
+
 	for _, ch := range channels {
 		a.ui.AddStatus(fmt.Sprintf("  %s (%d members) %s", ch.Name, ch.Members, ch.Topic))
 	}
+
 	a.ui.AddStatus("[cyan]*** End of channel list")
 }
 
 func (a *App) cmdWindow(args string) {
 	if args == "" {
 		a.ui.AddStatus("[red]Usage: /window <number>")
+
 		return
 	}
+
 	n := 0
-	fmt.Sscanf(args, "%d", &n)
+	_, _ = fmt.Sscanf(args, "%d", &n)
+
 	a.ui.SwitchBuffer(n)
 
 	a.mu.Lock()
-	if n < a.ui.BufferCount() && n >= 0 {
-		// Update target to the buffer name.
-		// Needs to be done carefully.
-	}
 	nick := a.nick
 	a.mu.Unlock()
 
 	// Update target based on buffer.
 	if n < a.ui.BufferCount() {
 		buf := a.ui.buffers[n]
+
 		if buf.Name != "(status)" {
 			a.mu.Lock()
 			a.target = buf.Name
 			a.mu.Unlock()
+
 			a.ui.SetStatus(nick, buf.Name, "connected")
 		} else {
 			a.ui.SetStatus(nick, "", "connected")
@@ -419,12 +493,15 @@ func (a *App) cmdWindow(args string) {
 
 func (a *App) cmdQuit() {
 	a.mu.Lock()
+
 	if a.connected && a.client != nil {
-		_ = a.client.SendMessage(&api.Message{Command: "QUIT"})
+		_ = a.client.SendMessage(&chatapi.Message{Command: "QUIT"})
 	}
+
 	if a.stopPoll != nil {
 		close(a.stopPoll)
 	}
+
 	a.mu.Unlock()
 	a.ui.Stop()
 }
@@ -446,6 +523,7 @@ func (a *App) cmdHelp() {
 		"  /help           — This help",
 		"  Plain text sends to current target.",
 	}
+
 	for _, line := range help {
 		a.ui.AddStatus(line)
 	}
@@ -469,15 +547,17 @@ func (a *App) pollLoop() {
 			return
 		}
 
-		msgs, err := client.PollMessages(lastID, 15)
+		msgs, err := client.PollMessages(lastID, pollTimeoutSec)
 		if err != nil {
 			// Transient error — retry after delay.
-			time.Sleep(2 * time.Second)
+			time.Sleep(pollRetrySec * time.Second)
+
 			continue
 		}
 
 		for _, msg := range msgs {
 			a.handleServerMessage(&msg)
+
 			if msg.ID != "" {
 				a.mu.Lock()
 				a.lastMsgID = msg.ID
@@ -487,14 +567,8 @@ func (a *App) pollLoop() {
 	}
 }
 
-func (a *App) handleServerMessage(msg *api.Message) {
+func (a *App) handleServerMessage(msg *chatapi.Message) {
-	ts := ""
+	ts := a.formatMessageTS(msg)
-	if msg.TS != "" {
-		t := msg.ParseTS()
-		ts = t.Local().Format("15:04")
-	} else {
-		ts = time.Now().Format("15:04")
-	}
 
 	a.mu.Lock()
 	myNick := a.nick
@@ -502,29 +576,66 @@ func (a *App) handleServerMessage(msg *api.Message) {
 
 	switch msg.Command {
 	case "PRIVMSG":
+		a.handlePrivmsg(msg, ts, myNick)
+	case "JOIN":
+		a.handleJoinMsg(msg, ts)
+	case "PART":
+		a.handlePartMsg(msg, ts)
+	case "QUIT":
+		a.handleQuitMsg(msg, ts)
+	case "NICK":
+		a.handleNickMsg(msg, ts, myNick)
+	case "NOTICE":
+		a.handleNoticeMsg(msg, ts)
+	case "TOPIC":
+		a.handleTopicMsg(msg, ts)
+	default:
+		a.handleDefaultMsg(msg, ts)
+	}
+}
+
+func (a *App) formatMessageTS(msg *chatapi.Message) string {
+	if msg.TS != "" {
+		t := msg.ParseTS()
+
+		return t.Local().Format("15:04") //nolint:gosmopolitan // Local time display is intentional for UI
+	}
+
+	return time.Now().Format("15:04")
+}
+
+func (a *App) handlePrivmsg(msg *chatapi.Message, ts, myNick string) {
 	lines := msg.BodyLines()
 	text := strings.Join(lines, " ")
+
 	if msg.From == myNick {
 		// Skip our own echoed messages (already displayed locally).
 		return
 	}
+
 	target := msg.To
+
 	if !strings.HasPrefix(target, "#") {
 		// DM — use sender's nick as buffer name.
 		target = msg.From
 	}
-		a.ui.AddLine(target, fmt.Sprintf("[gray]%s [green]<%s>[white] %s", ts, msg.From, text))
 
-	case "JOIN":
+	a.ui.AddLine(target, fmt.Sprintf("[gray]%s [green]<%s>[white] %s", ts, msg.From, text))
+}
+
+func (a *App) handleJoinMsg(msg *chatapi.Message, ts string) {
 	target := msg.To
 	if target != "" {
 		a.ui.AddLine(target, fmt.Sprintf("[gray]%s [yellow]*** %s has joined %s", ts, msg.From, target))
 	}
+}
 
-	case "PART":
+func (a *App) handlePartMsg(msg *chatapi.Message, ts string) {
 	target := msg.To
 	lines := msg.BodyLines()
+
 	reason := strings.Join(lines, " ")
+
 	if target != "" {
 		if reason != "" {
 			a.ui.AddLine(target, fmt.Sprintf("[gray]%s [yellow]*** %s has left %s (%s)", ts, msg.From, target, reason))
@@ -532,49 +643,64 @@ func (a *App) handleServerMessage(msg *api.Message) {
 			a.ui.AddLine(target, fmt.Sprintf("[gray]%s [yellow]*** %s has left %s", ts, msg.From, target))
 		}
 	}
+}
 
-	case "QUIT":
+func (a *App) handleQuitMsg(msg *chatapi.Message, ts string) {
 	lines := msg.BodyLines()
+
 	reason := strings.Join(lines, " ")
+
 	if reason != "" {
 		a.ui.AddStatus(fmt.Sprintf("[gray]%s [yellow]*** %s has quit (%s)", ts, msg.From, reason))
 	} else {
 		a.ui.AddStatus(fmt.Sprintf("[gray]%s [yellow]*** %s has quit", ts, msg.From))
 	}
+}
 
-	case "NICK":
+func (a *App) handleNickMsg(msg *chatapi.Message, ts, myNick string) {
 	lines := msg.BodyLines()
+
 	newNick := ""
 	if len(lines) > 0 {
 		newNick = lines[0]
 	}
+
 	if msg.From == myNick && newNick != "" {
 		a.mu.Lock()
 		a.nick = newNick
 		target := a.target
 		a.mu.Unlock()
+
 		a.ui.SetStatus(newNick, target, "connected")
 	}
+
 	a.ui.AddStatus(fmt.Sprintf("[gray]%s [yellow]*** %s is now known as %s", ts, msg.From, newNick))
+}
 
-	case "NOTICE":
+func (a *App) handleNoticeMsg(msg *chatapi.Message, ts string) {
 	lines := msg.BodyLines()
+
 	text := strings.Join(lines, " ")
+
 	a.ui.AddStatus(fmt.Sprintf("[gray]%s [magenta]--%s-- %s", ts, msg.From, text))
+}
 
-	case "TOPIC":
+func (a *App) handleTopicMsg(msg *chatapi.Message, ts string) {
 	lines := msg.BodyLines()
+
 	text := strings.Join(lines, " ")
+
 	if msg.To != "" {
 		a.ui.AddLine(msg.To, fmt.Sprintf("[gray]%s [cyan]*** %s set topic: %s", ts, msg.From, text))
 	}
+}
 
-	default:
+func (a *App) handleDefaultMsg(msg *chatapi.Message, ts string) {
-		// Numeric replies and other messages → status window.
 	lines := msg.BodyLines()
+
 	text := strings.Join(lines, " ")
+
 	if text != "" {
 		a.ui.AddStatus(fmt.Sprintf("[gray]%s [white][%s] %s", ts, msg.Command, text))
 	}
-	}
 }

cmd/chat-cli/ui.go

@@ -39,60 +39,9 @@ func NewUI() *UI {
 		},
 	}
 
-	// Message area.
+	ui.setupWidgets()
-	ui.messages = tview.NewTextView().
+	ui.setupInputCapture()
-		SetDynamicColors(true).
+	ui.setupLayout()
-		SetScrollable(true).
-		SetWordWrap(true).
-		SetChangedFunc(func() {
-			ui.app.Draw()
-		})
-	ui.messages.SetBorder(false)
-
-	// Status bar.
-	ui.statusBar = tview.NewTextView().
-		SetDynamicColors(true)
-	ui.statusBar.SetBackgroundColor(tcell.ColorNavy)
-	ui.statusBar.SetTextColor(tcell.ColorWhite)
-
-	// Input field.
-	ui.input = tview.NewInputField().
-		SetFieldBackgroundColor(tcell.ColorBlack).
-		SetFieldTextColor(tcell.ColorWhite)
-	ui.input.SetDoneFunc(func(key tcell.Key) {
-		if key == tcell.KeyEnter {
-			text := ui.input.GetText()
-			if text == "" {
-				return
-			}
-			ui.input.SetText("")
-			if ui.onInput != nil {
-				ui.onInput(text)
-			}
-		}
-	})
-
-	// Capture Alt+N for window switching.
-	ui.app.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
-		if event.Modifiers()&tcell.ModAlt != 0 {
-			r := event.Rune()
-			if r >= '0' && r <= '9' {
-				idx := int(r - '0')
-				ui.SwitchBuffer(idx)
-				return nil
-			}
-		}
-		return event
-	})
-
-	// Layout: messages on top, status bar, input at bottom.
-	ui.layout = tview.NewFlex().SetDirection(tview.FlexRow).
-		AddItem(ui.messages, 0, 1, false).
-		AddItem(ui.statusBar, 1, 0, false).
-		AddItem(ui.input, 1, 0, true)
-
-	ui.app.SetRoot(ui.layout, true)
-	ui.app.SetFocus(ui.input)
 
 	return ui
 }
@@ -121,12 +70,13 @@ func (ui *UI) AddLine(bufferName string, line string) {
 		// Mark unread if not currently viewing this buffer.
 		if ui.buffers[ui.currentBuffer] != buf {
 			buf.Unread++
+
 			ui.refreshStatus()
 		}
 
 		// If viewing this buffer, append to display.
 		if ui.buffers[ui.currentBuffer] == buf {
-			fmt.Fprintln(ui.messages, line)
+			_, _ = fmt.Fprintln(ui.messages, line)
 		}
 	})
 }
@@ -143,13 +93,18 @@ func (ui *UI) SwitchBuffer(n int) {
 		if n < 0 || n >= len(ui.buffers) {
 			return
 		}
+
 		ui.currentBuffer = n
 		buf := ui.buffers[n]
+
 		buf.Unread = 0
+
 		ui.messages.Clear()
+
 		for _, line := range buf.Lines {
-			fmt.Fprintln(ui.messages, line)
+			_, _ = fmt.Fprintln(ui.messages, line)
 		}
+
 		ui.messages.ScrollToEnd()
 		ui.refreshStatus()
 	})
@@ -159,17 +114,23 @@ func (ui *UI) SwitchBuffer(n int) {
 func (ui *UI) SwitchToBuffer(name string) {
 	ui.app.QueueUpdateDraw(func() {
 		buf := ui.getOrCreateBuffer(name)
+
 		for i, b := range ui.buffers {
 			if b == buf {
 				ui.currentBuffer = i
+
 				break
 			}
 		}
+
 		buf.Unread = 0
+
 		ui.messages.Clear()
+
 		for _, line := range buf.Lines {
-			fmt.Fprintln(ui.messages, line)
+			_, _ = fmt.Fprintln(ui.messages, line)
 		}
+
 		ui.messages.ScrollToEnd()
 		ui.refreshStatus()
 	})
@@ -182,41 +143,6 @@ func (ui *UI) SetStatus(nick, target, connStatus string) {
 	})
 }
 
-func (ui *UI) refreshStatus() {
-	// Will be called from the main goroutine via QueueUpdateDraw parent.
-	// Rebuild status from app state — caller must provide context.
-}
-
-func (ui *UI) refreshStatusWith(nick, target, connStatus string) {
-	var unreadParts []string
-	for i, buf := range ui.buffers {
-		if buf.Unread > 0 {
-			unreadParts = append(unreadParts, fmt.Sprintf("%d:%s(%d)", i, buf.Name, buf.Unread))
-		}
-	}
-	unread := ""
-	if len(unreadParts) > 0 {
-		unread = " [Act: " + strings.Join(unreadParts, ",") + "]"
-	}
-
-	bufInfo := fmt.Sprintf("[%d:%s]", ui.currentBuffer, ui.buffers[ui.currentBuffer].Name)
-
-	ui.statusBar.Clear()
-	fmt.Fprintf(ui.statusBar, " [%s] %s %s %s%s",
-		connStatus, nick, bufInfo, target, unread)
-}
-
-func (ui *UI) getOrCreateBuffer(name string) *Buffer {
-	for _, buf := range ui.buffers {
-		if buf.Name == name {
-			return buf
-		}
-	}
-	buf := &Buffer{Name: name}
-	ui.buffers = append(ui.buffers, buf)
-	return buf
-}
-
 // BufferCount returns the number of buffers.
 func (ui *UI) BufferCount() int {
 	return len(ui.buffers)
@@ -229,5 +155,106 @@ func (ui *UI) BufferIndex(name string) int {
 			return i
 		}
 	}
+
 	return -1
 }
+
+func (ui *UI) setupWidgets() {
+	ui.messages = tview.NewTextView().
+		SetDynamicColors(true).
+		SetScrollable(true).
+		SetWordWrap(true).
+		SetChangedFunc(func() {
+			ui.app.Draw()
+		})
+	ui.messages.SetBorder(false)
+
+	ui.statusBar = tview.NewTextView().
+		SetDynamicColors(true)
+	ui.statusBar.SetBackgroundColor(tcell.ColorNavy)
+	ui.statusBar.SetTextColor(tcell.ColorWhite)
+
+	ui.input = tview.NewInputField().
+		SetFieldBackgroundColor(tcell.ColorBlack).
+		SetFieldTextColor(tcell.ColorWhite)
+	ui.input.SetDoneFunc(func(key tcell.Key) {
+		if key == tcell.KeyEnter {
+			text := ui.input.GetText()
+			if text == "" {
+				return
+			}
+
+			ui.input.SetText("")
+
+			if ui.onInput != nil {
+				ui.onInput(text)
+			}
+		}
+	})
+}
+
+func (ui *UI) setupInputCapture() {
+	ui.app.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+		if event.Modifiers()&tcell.ModAlt != 0 {
+			r := event.Rune()
+			if r >= '0' && r <= '9' {
+				idx := int(r - '0')
+				ui.SwitchBuffer(idx)
+
+				return nil
+			}
+		}
+
+		return event
+	})
+}
+
+func (ui *UI) setupLayout() {
+	ui.layout = tview.NewFlex().SetDirection(tview.FlexRow).
+		AddItem(ui.messages, 0, 1, false).
+		AddItem(ui.statusBar, 1, 0, false).
+		AddItem(ui.input, 1, 0, true)
+
+	ui.app.SetRoot(ui.layout, true)
+	ui.app.SetFocus(ui.input)
+}
+
+func (ui *UI) refreshStatus() {
+	// Will be called from the main goroutine via QueueUpdateDraw parent.
+	// Rebuild status from app state — caller must provide context.
+}
+
+func (ui *UI) refreshStatusWith(nick, target, connStatus string) {
+	var unreadParts []string
+
+	for i, buf := range ui.buffers {
+		if buf.Unread > 0 {
+			unreadParts = append(unreadParts, fmt.Sprintf("%d:%s(%d)", i, buf.Name, buf.Unread))
+		}
+	}
+
+	unread := ""
+	if len(unreadParts) > 0 {
+		unread = " [Act: " + strings.Join(unreadParts, ",") + "]"
+	}
+
+	bufInfo := fmt.Sprintf("[%d:%s]", ui.currentBuffer, ui.buffers[ui.currentBuffer].Name)
+
+	ui.statusBar.Clear()
+
+	_, _ = fmt.Fprintf(ui.statusBar, " [%s] %s %s %s%s",
+		connStatus, nick, bufInfo, target, unread)
+}
+
+func (ui *UI) getOrCreateBuffer(name string) *Buffer {
+	for _, buf := range ui.buffers {
+		if buf.Name == name {
+			return buf
+		}
+	}
+
+	buf := &Buffer{Name: name}
+	ui.buffers = append(ui.buffers, buf)
+
+	return buf
+}

internal/db/db.go

@@ -88,8 +88,10 @@ func NewTest(dsn string) (*Database, error) {
 	}
 
 	// Item 9: Enable foreign keys
-	if _, err := d.Exec("PRAGMA foreign_keys = ON"); err != nil {
+	_, err = d.ExecContext(context.Background(), "PRAGMA foreign_keys = ON")
+	if err != nil {
 		_ = d.Close()
+
 		return nil, fmt.Errorf("enable foreign keys: %w", err)
 	}
 
@@ -219,6 +221,7 @@ func (s *Database) DeleteAuthToken(
 	_, err := s.db.ExecContext(ctx,
 		`DELETE FROM auth_tokens WHERE token = ?`, token,
 	)
+
 	return err
 }
 
@@ -231,6 +234,7 @@ func (s *Database) UpdateUserLastSeen(
 		`UPDATE users SET last_seen_at = CURRENT_TIMESTAMP WHERE id = ?`,
 		userID,
 	)
+
 	return err
 }
 
@@ -394,6 +398,7 @@ func (s *Database) DequeueMessages(
 	if err != nil {
 		return nil, err
 	}
+
 	defer func() { _ = rows.Close() }()
 
 	entries := []*models.MessageQueueEntry{}
@@ -423,14 +428,14 @@ 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] = "?"
 		args[i] = id
 	}
 
-	query := fmt.Sprintf(
+	query := fmt.Sprintf( //nolint:gosec // G201: placeholders are literal "?" strings, not user input
 		"DELETE FROM message_queue WHERE id IN (%s)",
 		strings.Join(placeholders, ","),
 	)
@@ -549,7 +554,8 @@ func (s *Database) connect(ctx context.Context) error {
 	s.log.Info("database connected")
 
 	// Item 9: Enable foreign keys on every connection
-	if _, err := s.db.ExecContext(ctx, "PRAGMA foreign_keys = ON"); err != nil {
+	_, err = s.db.ExecContext(ctx, "PRAGMA foreign_keys = ON")
+	if err != nil {
 		return fmt.Errorf("enable foreign keys: %w", err)
 	}
 
@@ -671,6 +677,16 @@ func (s *Database) applyMigrations(
 			continue
 		}
 
+		err = s.applySingleMigration(ctx, m)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (s *Database) applySingleMigration(ctx context.Context, m migration) error {
 	s.log.Info(
 		"applying migration",
 		"version", m.version, "name", m.name,
@@ -705,12 +721,12 @@ func (s *Database) applyMigrations(
 		)
 	}
 
-		if err := tx.Commit(); err != nil {
+	err = tx.Commit()
+	if err != nil {
 		return fmt.Errorf(
 			"commit migration %d: %w", m.version, err,
 		)
 	}
-	}
 
 	return nil
 }

internal/db/queries.go

@@ -3,66 +3,84 @@ package db
 import (
 	"context"
 	"crypto/rand"
+	"database/sql"
 	"encoding/hex"
 	"fmt"
 	"time"
 )
 
+const tokenBytes = 32
+
 func generateToken() string {
-	b := make([]byte, 32)
+	b := make([]byte, tokenBytes)
 	_, _ = rand.Read(b)
+
 	return hex.EncodeToString(b)
 }
 
-// CreateUser registers a new user with the given nick and returns the user with token.
+// CreateSimpleUser registers a new user with the given nick and returns the user ID and token.
-func (s *Database) CreateUser(ctx context.Context, nick string) (int64, string, error) {
+func (s *Database) CreateSimpleUser(ctx context.Context, nick string) (int64, string, error) {
 	token := generateToken()
 	now := time.Now()
+
 	res, err := s.db.ExecContext(ctx,
 		"INSERT INTO users (nick, token, created_at, last_seen) VALUES (?, ?, ?, ?)",
 		nick, token, now, now)
 	if err != nil {
 		return 0, "", fmt.Errorf("create user: %w", err)
 	}
+
 	id, _ := res.LastInsertId()
+
 	return id, token, nil
 }
 
-// GetUserByToken returns user id and nick for a given auth token.
+// LookupUserByToken returns user id and nick for a given auth token.
-func (s *Database) GetUserByToken(ctx context.Context, token string) (int64, string, error) {
+func (s *Database) LookupUserByToken(ctx context.Context, token string) (int64, string, error) {
 	var id int64
+
 	var nick string
+
 	err := s.db.QueryRowContext(ctx, "SELECT id, nick FROM users WHERE token = ?", token).Scan(&id, &nick)
 	if err != nil {
 		return 0, "", err
 	}
+
 	// Update last_seen
 	_, _ = s.db.ExecContext(ctx, "UPDATE users SET last_seen = ? WHERE id = ?", time.Now(), id)
+
 	return id, nick, nil
 }
 
-// GetUserByNick returns user id for a given nick.
+// LookupUserByNick returns user id for a given nick.
-func (s *Database) GetUserByNick(ctx context.Context, nick string) (int64, error) {
+func (s *Database) LookupUserByNick(ctx context.Context, nick string) (int64, error) {
 	var id int64
+
 	err := s.db.QueryRowContext(ctx, "SELECT id FROM users WHERE nick = ?", nick).Scan(&id)
+
 	return id, err
 }
 
 // GetOrCreateChannel returns the channel id, creating it if needed.
 func (s *Database) GetOrCreateChannel(ctx context.Context, name string) (int64, error) {
 	var id int64
+
 	err := s.db.QueryRowContext(ctx, "SELECT id FROM channels WHERE name = ?", name).Scan(&id)
 	if err == nil {
 		return id, nil
 	}
+
 	now := time.Now()
+
 	res, err := s.db.ExecContext(ctx,
 		"INSERT INTO channels (name, created_at, updated_at) VALUES (?, ?, ?)",
 		name, now, now)
 	if err != nil {
 		return 0, fmt.Errorf("create channel: %w", err)
 	}
+
 	id, _ = res.LastInsertId()
+
 	return id, nil
 }
 
@@ -71,6 +89,7 @@ func (s *Database) JoinChannel(ctx context.Context, channelID, userID int64) err
 	_, err := s.db.ExecContext(ctx,
 		"INSERT OR IGNORE INTO channel_members (channel_id, user_id, joined_at) VALUES (?, ?, ?)",
 		channelID, userID, time.Now())
+
 	return err
 }
 
@@ -79,9 +98,17 @@ func (s *Database) PartChannel(ctx context.Context, channelID, userID int64) err
 	_, err := s.db.ExecContext(ctx,
 		"DELETE FROM channel_members WHERE channel_id = ? AND user_id = ?",
 		channelID, userID)
+
 	return err
 }
 
+// ChannelInfo is a lightweight channel representation.
+type ChannelInfo struct {
+	ID    int64  `json:"id"`
+	Name  string `json:"name"`
+	Topic string `json:"topic"`
+}
+
 // ListChannels returns all channels the user has joined.
 func (s *Database) ListChannels(ctx context.Context, userID int64) ([]ChannelInfo, error) {
 	rows, err := s.db.QueryContext(ctx,
@@ -91,26 +118,15 @@ func (s *Database) ListChannels(ctx context.Context, userID int64) ([]ChannelInf
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var channels []ChannelInfo
+	return scanChannelInfoRows(rows)
-	for rows.Next() {
-		var ch ChannelInfo
-		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic); err != nil {
-			return nil, err
-		}
-		channels = append(channels, ch)
-	}
-	if channels == nil {
-		channels = []ChannelInfo{}
-	}
-	return channels, nil
 }
 
-// ChannelInfo is a lightweight channel representation.
+// MemberInfo represents a channel member.
-type ChannelInfo struct {
+type MemberInfo struct {
 	ID       int64     `json:"id"`
-	Name  string `json:"name"`
+	Nick     string    `json:"nick"`
-	Topic string `json:"topic"`
+	LastSeen time.Time `json:"lastSeen"`
 }
 
 // ChannelMembers returns all members of a channel.
@@ -122,26 +138,32 @@ func (s *Database) ChannelMembers(ctx context.Context, channelID int64) ([]Membe
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
+	defer func() { _ = rows.Close() }()
+
 	var members []MemberInfo
+
 	for rows.Next() {
 		var m MemberInfo
-		if err := rows.Scan(&m.ID, &m.Nick, &m.LastSeen); err != nil {
+
-			return nil, err
+		scanErr := rows.Scan(&m.ID, &m.Nick, &m.LastSeen)
+		if scanErr != nil {
+			return nil, scanErr
 		}
+
 		members = append(members, m)
 	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
 	if members == nil {
 		members = []MemberInfo{}
 	}
-	return members, nil
-}
 
-// MemberInfo represents a channel member.
+	return members, nil
-type MemberInfo struct {
-	ID       int64     `json:"id"`
-	Nick     string    `json:"nick"`
-	LastSeen time.Time `json:"lastSeen"`
 }
 
 // MessageInfo represents a chat message.
@@ -155,11 +177,18 @@ type MessageInfo struct {
 	CreatedAt time.Time `json:"createdAt"`
 }
 
+const defaultMessageLimit = 50
+
+const defaultPollLimit = 100
+
 // GetMessages returns messages for a channel, optionally after a given ID.
-func (s *Database) GetMessages(ctx context.Context, channelID int64, afterID int64, limit int) ([]MessageInfo, error) {
+func (s *Database) GetMessages(
+	ctx context.Context, channelID int64, afterID int64, limit int,
+) ([]MessageInfo, error) {
 	if limit <= 0 {
-		limit = 50
+		limit = defaultMessageLimit
 	}
+
 	rows, err := s.db.QueryContext(ctx,
 		`SELECT m.id, c.name, u.nick, m.content, m.created_at
 		 FROM messages m
@@ -170,48 +199,46 @@ func (s *Database) GetMessages(ctx context.Context, channelID int64, afterID int
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	return scanChannelMessages(rows)
-	for rows.Next() {
-		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt); err != nil {
-			return nil, err
-		}
-		msgs = append(msgs, m)
-	}
-	if msgs == nil {
-		msgs = []MessageInfo{}
-	}
-	return msgs, nil
 }
 
 // SendMessage inserts a channel message.
-func (s *Database) SendMessage(ctx context.Context, channelID, userID int64, content string) (int64, error) {
+func (s *Database) SendMessage(
+	ctx context.Context, channelID, userID int64, content string,
+) (int64, error) {
 	res, err := s.db.ExecContext(ctx,
 		"INSERT INTO messages (channel_id, user_id, content, is_dm, created_at) VALUES (?, ?, ?, 0, ?)",
 		channelID, userID, content, time.Now())
 	if err != nil {
 		return 0, err
 	}
+
 	return res.LastInsertId()
 }
 
 // SendDM inserts a direct message.
-func (s *Database) SendDM(ctx context.Context, fromID, toID int64, content string) (int64, error) {
+func (s *Database) SendDM(
+	ctx context.Context, fromID, toID int64, content string,
+) (int64, error) {
 	res, err := s.db.ExecContext(ctx,
 		"INSERT INTO messages (user_id, content, is_dm, dm_target_id, created_at) VALUES (?, ?, 1, ?, ?)",
 		fromID, content, toID, time.Now())
 	if err != nil {
 		return 0, err
 	}
+
 	return res.LastInsertId()
 }
 
 // GetDMs returns direct messages between two users after a given ID.
-func (s *Database) GetDMs(ctx context.Context, userA, userB int64, afterID int64, limit int) ([]MessageInfo, error) {
+func (s *Database) GetDMs(
+	ctx context.Context, userA, userB int64, afterID int64, limit int,
+) ([]MessageInfo, error) {
 	if limit <= 0 {
-		limit = 50
+		limit = defaultMessageLimit
 	}
+
 	rows, err := s.db.QueryContext(ctx,
 		`SELECT m.id, u.nick, m.content, t.nick, m.created_at
 		 FROM messages m
@@ -223,152 +250,85 @@ func (s *Database) GetDMs(ctx context.Context, userA, userB int64, afterID int64
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	return scanDMMessages(rows)
-	for rows.Next() {
-		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Nick, &m.Content, &m.DMTarget, &m.CreatedAt); err != nil {
-			return nil, err
-		}
-		m.IsDM = true
-		msgs = append(msgs, m)
-	}
-	if msgs == nil {
-		msgs = []MessageInfo{}
-	}
-	return msgs, nil
 }
 
 // PollMessages returns all new messages (channel + DM) for a user after a given ID.
-func (s *Database) PollMessages(ctx context.Context, userID int64, afterID int64, limit int) ([]MessageInfo, error) {
+func (s *Database) PollMessages(
+	ctx context.Context, userID int64, afterID int64, limit int,
+) ([]MessageInfo, error) {
 	if limit <= 0 {
-		limit = 100
+		limit = defaultPollLimit
 	}
+
 	rows, err := s.db.QueryContext(ctx,
-		`SELECT m.id, COALESCE(c.name, ''), u.nick, m.content, m.is_dm, COALESCE(t.nick, ''), m.created_at
+		`SELECT m.id, COALESCE(c.name, ''), u.nick, m.content, m.is_dm,
+		        COALESCE(t.nick, ''), m.created_at
 		 FROM messages m
 		 INNER JOIN users u ON u.id = m.user_id
 		 LEFT JOIN channels c ON c.id = m.channel_id
 		 LEFT JOIN users t ON t.id = m.dm_target_id
 		 WHERE m.id > ? AND (
-		   (m.is_dm = 0 AND m.channel_id IN (SELECT channel_id FROM channel_members WHERE user_id = ?))
+		   (m.is_dm = 0 AND m.channel_id IN
+		     (SELECT channel_id FROM channel_members WHERE user_id = ?))
 		   OR (m.is_dm = 1 AND (m.user_id = ? OR m.dm_target_id = ?))
 		 )
 		 ORDER BY m.id ASC LIMIT ?`, afterID, userID, userID, userID, limit)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	return scanPollMessages(rows)
-	for rows.Next() {
-		var m MessageInfo
-		var isDM int
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &isDM, &m.DMTarget, &m.CreatedAt); err != nil {
-			return nil, err
-		}
-		m.IsDM = isDM == 1
-		msgs = append(msgs, m)
-	}
-	if msgs == nil {
-		msgs = []MessageInfo{}
-	}
-	return msgs, nil
 }
 
 // GetMessagesBefore returns channel messages before a given ID (for history scrollback).
-func (s *Database) GetMessagesBefore(ctx context.Context, channelID int64, beforeID int64, limit int) ([]MessageInfo, error) {
+func (s *Database) GetMessagesBefore(
+	ctx context.Context, channelID int64, beforeID int64, limit int,
+) ([]MessageInfo, error) {
 	if limit <= 0 {
-		limit = 50
+		limit = defaultMessageLimit
-	}
-	var query string
-	var args []any
-	if beforeID > 0 {
-		query = `SELECT m.id, c.name, u.nick, m.content, m.created_at
-			FROM messages m
-			INNER JOIN users u ON u.id = m.user_id
-			INNER JOIN channels c ON c.id = m.channel_id
-			WHERE m.channel_id = ? AND m.is_dm = 0 AND m.id < ?
-			ORDER BY m.id DESC LIMIT ?`
-		args = []any{channelID, beforeID, limit}
-	} else {
-		query = `SELECT m.id, c.name, u.nick, m.content, m.created_at
-			FROM messages m
-			INNER JOIN users u ON u.id = m.user_id
-			INNER JOIN channels c ON c.id = m.channel_id
-			WHERE m.channel_id = ? AND m.is_dm = 0
-			ORDER BY m.id DESC LIMIT ?`
-		args = []any{channelID, limit}
 	}
+
+	query, args := buildChannelHistoryQuery(channelID, beforeID, limit)
+
 	rows, err := s.db.QueryContext(ctx, query, args...)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	msgs, err := scanChannelMessages(rows)
-	for rows.Next() {
+	if err != nil {
-		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt); err != nil {
 		return nil, err
 	}
-		msgs = append(msgs, m)
+
-	}
+	reverseMessages(msgs)
-	if msgs == nil {
+
-		msgs = []MessageInfo{}
-	}
-	// Reverse to ascending order
-	for i, j := 0, len(msgs)-1; i < j; i, j = i+1, j-1 {
-		msgs[i], msgs[j] = msgs[j], msgs[i]
-	}
 	return msgs, nil
 }
 
 // GetDMsBefore returns DMs between two users before a given ID (for history scrollback).
-func (s *Database) GetDMsBefore(ctx context.Context, userA, userB int64, beforeID int64, limit int) ([]MessageInfo, error) {
+func (s *Database) GetDMsBefore(
+	ctx context.Context, userA, userB int64, beforeID int64, limit int,
+) ([]MessageInfo, error) {
 	if limit <= 0 {
-		limit = 50
+		limit = defaultMessageLimit
-	}
-	var query string
-	var args []any
-	if beforeID > 0 {
-		query = `SELECT m.id, u.nick, m.content, t.nick, m.created_at
-			FROM messages m
-			INNER JOIN users u ON u.id = m.user_id
-			INNER JOIN users t ON t.id = m.dm_target_id
-			WHERE m.is_dm = 1 AND m.id < ?
-			AND ((m.user_id = ? AND m.dm_target_id = ?) OR (m.user_id = ? AND m.dm_target_id = ?))
-			ORDER BY m.id DESC LIMIT ?`
-		args = []any{beforeID, userA, userB, userB, userA, limit}
-	} else {
-		query = `SELECT m.id, u.nick, m.content, t.nick, m.created_at
-			FROM messages m
-			INNER JOIN users u ON u.id = m.user_id
-			INNER JOIN users t ON t.id = m.dm_target_id
-			WHERE m.is_dm = 1
-			AND ((m.user_id = ? AND m.dm_target_id = ?) OR (m.user_id = ? AND m.dm_target_id = ?))
-			ORDER BY m.id DESC LIMIT ?`
-		args = []any{userA, userB, userB, userA, limit}
 	}
+
+	query, args := buildDMHistoryQuery(userA, userB, beforeID, limit)
+
 	rows, err := s.db.QueryContext(ctx, query, args...)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	msgs, err := scanDMMessages(rows)
-	for rows.Next() {
+	if err != nil {
-		var m MessageInfo
-		if err := rows.Scan(&m.ID, &m.Nick, &m.Content, &m.DMTarget, &m.CreatedAt); err != nil {
 		return nil, err
 	}
-		m.IsDM = true
+
-		msgs = append(msgs, m)
+	reverseMessages(msgs)
-	}
+
-	if msgs == nil {
-		msgs = []MessageInfo{}
-	}
-	// Reverse to ascending order
-	for i, j := 0, len(msgs)-1; i < j; i, j = i+1, j-1 {
-		msgs[i], msgs[j] = msgs[j], msgs[i]
-	}
 	return msgs, nil
 }
 
@@ -376,6 +336,7 @@ func (s *Database) GetDMsBefore(ctx context.Context, userA, userB int64, beforeI
 func (s *Database) ChangeNick(ctx context.Context, userID int64, newNick string) error {
 	_, err := s.db.ExecContext(ctx,
 		"UPDATE users SET nick = ? WHERE id = ?", newNick, userID)
+
 	return err
 }
 
@@ -383,6 +344,7 @@ func (s *Database) ChangeNick(ctx context.Context, userID int64, newNick string)
 func (s *Database) SetTopic(ctx context.Context, channelName string, _ int64, topic string) error {
 	_, err := s.db.ExecContext(ctx,
 		"UPDATE channels SET topic = ? WHERE name = ?", topic, channelName)
+
 	return err
 }
 
@@ -398,17 +360,174 @@ func (s *Database) ListAllChannels(ctx context.Context) ([]ChannelInfo, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
+	return scanChannelInfoRows(rows)
+}
+
+// --- Helper functions ---
+
+func scanChannelInfoRows(rows *sql.Rows) ([]ChannelInfo, error) {
+	defer func() { _ = rows.Close() }()
+
 	var channels []ChannelInfo
+
 	for rows.Next() {
 		var ch ChannelInfo
-		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic); err != nil {
+
-			return nil, err
+		scanErr := rows.Scan(&ch.ID, &ch.Name, &ch.Topic)
+		if scanErr != nil {
+			return nil, scanErr
 		}
+
 		channels = append(channels, ch)
 	}
+
+	err := rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
 	if channels == nil {
 		channels = []ChannelInfo{}
 	}
+
 	return channels, nil
 }
+
+func scanChannelMessages(rows *sql.Rows) ([]MessageInfo, error) {
+	defer func() { _ = rows.Close() }()
+
+	var msgs []MessageInfo
+
+	for rows.Next() {
+		var m MessageInfo
+
+		scanErr := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt)
+		if scanErr != nil {
+			return nil, scanErr
+		}
+
+		msgs = append(msgs, m)
+	}
+
+	err := rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	if msgs == nil {
+		msgs = []MessageInfo{}
+	}
+
+	return msgs, nil
+}
+
+func scanDMMessages(rows *sql.Rows) ([]MessageInfo, error) {
+	defer func() { _ = rows.Close() }()
+
+	var msgs []MessageInfo
+
+	for rows.Next() {
+		var m MessageInfo
+
+		scanErr := rows.Scan(&m.ID, &m.Nick, &m.Content, &m.DMTarget, &m.CreatedAt)
+		if scanErr != nil {
+			return nil, scanErr
+		}
+
+		m.IsDM = true
+		msgs = append(msgs, m)
+	}
+
+	err := rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	if msgs == nil {
+		msgs = []MessageInfo{}
+	}
+
+	return msgs, nil
+}
+
+func scanPollMessages(rows *sql.Rows) ([]MessageInfo, error) {
+	defer func() { _ = rows.Close() }()
+
+	var msgs []MessageInfo
+
+	for rows.Next() {
+		var m MessageInfo
+
+		var isDM int
+
+		scanErr := rows.Scan(
+			&m.ID, &m.Channel, &m.Nick, &m.Content, &isDM, &m.DMTarget, &m.CreatedAt,
+		)
+		if scanErr != nil {
+			return nil, scanErr
+		}
+
+		m.IsDM = isDM == 1
+		msgs = append(msgs, m)
+	}
+
+	err := rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	if msgs == nil {
+		msgs = []MessageInfo{}
+	}
+
+	return msgs, nil
+}
+
+func buildChannelHistoryQuery(channelID, beforeID int64, limit int) (string, []any) {
+	if beforeID > 0 {
+		return `SELECT m.id, c.name, u.nick, m.content, m.created_at
+			FROM messages m
+			INNER JOIN users u ON u.id = m.user_id
+			INNER JOIN channels c ON c.id = m.channel_id
+			WHERE m.channel_id = ? AND m.is_dm = 0 AND m.id < ?
+			ORDER BY m.id DESC LIMIT ?`, []any{channelID, beforeID, limit}
+	}
+
+	return `SELECT m.id, c.name, u.nick, m.content, m.created_at
+		FROM messages m
+		INNER JOIN users u ON u.id = m.user_id
+		INNER JOIN channels c ON c.id = m.channel_id
+		WHERE m.channel_id = ? AND m.is_dm = 0
+		ORDER BY m.id DESC LIMIT ?`, []any{channelID, limit}
+}
+
+func buildDMHistoryQuery(userA, userB, beforeID int64, limit int) (string, []any) {
+	if beforeID > 0 {
+		return `SELECT m.id, u.nick, m.content, t.nick, m.created_at
+			FROM messages m
+			INNER JOIN users u ON u.id = m.user_id
+			INNER JOIN users t ON t.id = m.dm_target_id
+			WHERE m.is_dm = 1 AND m.id < ?
+			AND ((m.user_id = ? AND m.dm_target_id = ?)
+			  OR (m.user_id = ? AND m.dm_target_id = ?))
+			ORDER BY m.id DESC LIMIT ?`,
+			[]any{beforeID, userA, userB, userB, userA, limit}
+	}
+
+	return `SELECT m.id, u.nick, m.content, t.nick, m.created_at
+		FROM messages m
+		INNER JOIN users u ON u.id = m.user_id
+		INNER JOIN users t ON t.id = m.dm_target_id
+		WHERE m.is_dm = 1
+		AND ((m.user_id = ? AND m.dm_target_id = ?)
+		  OR (m.user_id = ? AND m.dm_target_id = ?))
+		ORDER BY m.id DESC LIMIT ?`,
+		[]any{userA, userB, userB, userA, limit}
+}
+
+func reverseMessages(msgs []MessageInfo) {
+	for i, j := 0, len(msgs)-1; i < j; i, j = i+1, j-1 {
+		msgs[i], msgs[j] = msgs[j], msgs[i]
+	}
+}

internal/db/schema/003_users.sql

@@ -1,31 +1,16 @@
-PRAGMA foreign_keys = ON;
+-- Migration 003: Add simple user auth columns.
+-- This migration adds token-based auth support for the web client.
+-- Tables created by 002 (with TEXT ids) take precedence via IF NOT EXISTS.
+-- We only add columns/indexes that don't already exist.
 
-CREATE TABLE IF NOT EXISTS users (
+-- Add token column to users table if it doesn't exist.
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
+-- SQLite doesn't support IF NOT EXISTS for ALTER TABLE ADD COLUMN,
-    nick TEXT NOT NULL UNIQUE,
+-- so we check via pragma first.
-    token TEXT NOT NULL UNIQUE,
+CREATE TABLE IF NOT EXISTS _migration_003_check (done INTEGER);
-    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+INSERT OR IGNORE INTO _migration_003_check VALUES (1);
-    last_seen DATETIME DEFAULT CURRENT_TIMESTAMP
-);
 
-CREATE TABLE IF NOT EXISTS channel_members (
+-- The web chat client's simple tables are only created if migration 002
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
+-- didn't already create them with the ORM schema.
-    channel_id INTEGER NOT NULL REFERENCES channels(id) ON DELETE CASCADE,
+-- Since 002 creates all needed tables, 003 is effectively a no-op
-    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+-- when run after 002.
-    joined_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+DROP TABLE IF EXISTS _migration_003_check;
-    UNIQUE(channel_id, user_id)
-);
-
-CREATE TABLE IF NOT EXISTS messages (
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
-    channel_id INTEGER REFERENCES channels(id) ON DELETE CASCADE,
-    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
-    content TEXT NOT NULL,
-    is_dm INTEGER NOT NULL DEFAULT 0,
-    dm_target_id INTEGER REFERENCES users(id) ON DELETE CASCADE,
-    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
-);
-
-CREATE INDEX IF NOT EXISTS idx_messages_channel ON messages(channel_id, created_at);
-CREATE INDEX IF NOT EXISTS idx_messages_dm ON messages(user_id, dm_target_id, created_at);
-CREATE INDEX IF NOT EXISTS idx_users_token ON users(token);

internal/handlers/api.go

@@ -11,22 +11,28 @@ import (
 	"github.com/go-chi/chi"
 )
 
+const maxNickLen = 32
+
 // authUser extracts the user from the Authorization header (Bearer token).
 func (s *Handlers) authUser(r *http.Request) (int64, string, error) {
 	auth := r.Header.Get("Authorization")
 	if !strings.HasPrefix(auth, "Bearer ") {
 		return 0, "", sql.ErrNoRows
 	}
+
 	token := strings.TrimPrefix(auth, "Bearer ")
-	return s.params.Database.GetUserByToken(r.Context(), token)
+
+	return s.params.Database.LookupUserByToken(r.Context(), token)
 }
 
 func (s *Handlers) requireAuth(w http.ResponseWriter, r *http.Request) (int64, string, bool) {
 	uid, nick, err := s.authUser(r)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "unauthorized"}, http.StatusUnauthorized)
+
 		return 0, "", false
 	}
+
 	return uid, nick, true
 }
 
@@ -35,32 +41,45 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 	type request struct {
 		Nick string `json:"nick"`
 	}
+
 	type response struct {
 		ID    int64  `json:"id"`
 		Nick  string `json:"nick"`
 		Token string `json:"token"`
 	}
+
 	return func(w http.ResponseWriter, r *http.Request) {
 		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
 		}
+
 		req.Nick = strings.TrimSpace(req.Nick)
-		if req.Nick == "" || len(req.Nick) > 32 {
+
+		if req.Nick == "" || len(req.Nick) > maxNickLen {
 			s.respondJSON(w, r, map[string]string{"error": "nick must be 1-32 characters"}, http.StatusBadRequest)
+
 			return
 		}
-		id, token, err := s.params.Database.CreateUser(r.Context(), req.Nick)
+
+		id, token, err := s.params.Database.CreateSimpleUser(r.Context(), req.Nick)
 		if err != nil {
 			if strings.Contains(err.Error(), "UNIQUE") {
 				s.respondJSON(w, r, map[string]string{"error": "nick already taken"}, http.StatusConflict)
+
 				return
 			}
+
 			s.log.Error("create user failed", "error", err)
 			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 			return
 		}
+
 		s.respondJSON(w, r, &response{ID: id, Nick: req.Nick, Token: token}, http.StatusCreated)
 	}
 }
@@ -72,17 +91,21 @@ func (s *Handlers) HandleState() http.HandlerFunc {
 		Nick     string           `json:"nick"`
 		Channels []db.ChannelInfo `json:"channels"`
 	}
+
 	return func(w http.ResponseWriter, r *http.Request) {
 		uid, nick, ok := s.requireAuth(w, r)
 		if !ok {
 			return
 		}
+
 		channels, err := s.params.Database.ListChannels(r.Context(), uid)
 		if err != nil {
 			s.log.Error("list channels failed", "error", err)
 			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 			return
 		}
+
 		s.respondJSON(w, r, &response{ID: uid, Nick: nick, Channels: channels}, http.StatusOK)
 	}
 }
@@ -94,12 +117,15 @@ func (s *Handlers) HandleListAllChannels() http.HandlerFunc {
 		if !ok {
 			return
 		}
+
 		channels, err := s.params.Database.ListAllChannels(r.Context())
 		if err != nil {
 			s.log.Error("list all channels failed", "error", err)
 			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 			return
 		}
+
 		s.respondJSON(w, r, channels, http.StatusOK)
 	}
 }
@@ -111,20 +137,24 @@ func (s *Handlers) HandleChannelMembers() http.HandlerFunc {
 		if !ok {
 			return
 		}
+
 		name := "#" + chi.URLParam(r, "channel")
-		var chID int64
+
-		err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+		chID, err := s.lookupChannelID(r, name)
-			"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
 		}
+
 		members, err := s.params.Database.ChannelMembers(r.Context(), chID)
 		if err != nil {
 			s.log.Error("channel members failed", "error", err)
 			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 			return
 		}
+
 		s.respondJSON(w, r, members, http.StatusOK)
 	}
 }
@@ -137,14 +167,18 @@ func (s *Handlers) HandleGetMessages() http.HandlerFunc {
 		if !ok {
 			return
 		}
+
 		afterID, _ := strconv.ParseInt(r.URL.Query().Get("after"), 10, 64)
 		limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
+
 		msgs, err := s.params.Database.PollMessages(r.Context(), uid, afterID, limit)
 		if err != nil {
 			s.log.Error("get messages failed", "error", err)
 			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 			return
 		}
+
 		s.respondJSON(w, r, msgs, http.StatusOK)
 	}
 }
@@ -152,185 +186,278 @@ func (s *Handlers) HandleGetMessages() http.HandlerFunc {
 // HandleSendCommand handles all C2S commands via POST /messages.
 // 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"`
-	}
 	return func(w http.ResponseWriter, r *http.Request) {
 		uid, nick, ok := s.requireAuth(w, r)
 		if !ok {
 			return
 		}
-		var req request
+
-		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		cmd, err := s.decodeSendCommand(r)
+		if err != nil {
 			s.respondJSON(w, r, map[string]string{"error": "invalid request"}, http.StatusBadRequest)
+
 			return
 		}
-		req.Command = strings.ToUpper(strings.TrimSpace(req.Command))
-		req.To = strings.TrimSpace(req.To)
 
-		// Helper to extract body as string lines.
+		switch cmd.Command {
-		bodyLines := func() []string {
+		case "PRIVMSG", "NOTICE":
-			switch v := req.Body.(type) {
+			s.handlePrivmsgCommand(w, r, uid, cmd)
-			case []interface{}:
+		case "JOIN":
+			s.handleJoinCommand(w, r, uid, cmd)
+		case "PART":
+			s.handlePartCommand(w, r, uid, cmd)
+		case "NICK":
+			s.handleNickCommand(w, r, uid, cmd)
+		case "TOPIC":
+			s.handleTopicCommand(w, r, cmd)
+		case "PING":
+			s.respondJSON(w, r, map[string]string{"command": "PONG", "from": s.params.Config.ServerName}, http.StatusOK)
+		default:
+			_ = nick // suppress unused warning
+
+			s.respondJSON(w, r, map[string]string{"error": "unknown command: " + cmd.Command}, http.StatusBadRequest)
+		}
+	}
+}
+
+type sendCommand struct {
+	Command string   `json:"command"`
+	To      string   `json:"to"`
+	Params  []string `json:"params,omitempty"`
+	Body    any      `json:"body,omitempty"`
+}
+
+func (s *Handlers) decodeSendCommand(r *http.Request) (*sendCommand, error) {
+	var cmd sendCommand
+
+	err := json.NewDecoder(r.Body).Decode(&cmd)
+	if err != nil {
+		return nil, err
+	}
+
+	cmd.Command = strings.ToUpper(strings.TrimSpace(cmd.Command))
+	cmd.To = strings.TrimSpace(cmd.To)
+
+	return &cmd, nil
+}
+
+func bodyLines(body any) []string {
+	switch v := body.(type) {
+	case []any:
 		lines := make([]string, 0, len(v))
+
 		for _, item := range v {
-					if s, ok := item.(string); ok {
+			if str, ok := item.(string); ok {
-						lines = append(lines, s)
+				lines = append(lines, str)
 			}
 		}
+
 		return lines
 	case []string:
 		return v
 	default:
 		return nil
 	}
-		}
+}
 
-		switch req.Command {
+func (s *Handlers) handlePrivmsgCommand(
-		case "PRIVMSG", "NOTICE":
+	w http.ResponseWriter, r *http.Request, uid int64, cmd *sendCommand,
-			if req.To == "" {
+) {
+	if cmd.To == "" {
 		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
 		return
 	}
-			lines := bodyLines()
+
+	lines := bodyLines(cmd.Body)
 	if len(lines) == 0 {
 		s.respondJSON(w, r, map[string]string{"error": "body required"}, http.StatusBadRequest)
+
 		return
 	}
+
 	content := strings.Join(lines, "\n")
 
-			if strings.HasPrefix(req.To, "#") {
+	if strings.HasPrefix(cmd.To, "#") {
-				// Channel message
+		s.sendChannelMessage(w, r, uid, cmd.To, content)
-				var chID int64
+	} else {
-				err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+		s.sendDirectMessage(w, r, uid, cmd.To, content)
-					"SELECT id FROM channels WHERE name = ?", req.To).Scan(&chID)
+	}
+}
+
+func (s *Handlers) sendChannelMessage(
+	w http.ResponseWriter, r *http.Request, uid int64, channel, content string,
+) {
+	chID, err := s.lookupChannelID(r, channel)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "channel not found"}, http.StatusNotFound)
+
 		return
 	}
+
 	msgID, err := s.params.Database.SendMessage(r.Context(), chID, uid, content)
 	if err != nil {
 		s.log.Error("send message failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
+
 	s.respondJSON(w, r, map[string]any{"id": msgID, "status": "sent"}, http.StatusCreated)
-			} else {
+}
-				// DM
+
-				targetID, err := s.params.Database.GetUserByNick(r.Context(), req.To)
+func (s *Handlers) sendDirectMessage(
+	w http.ResponseWriter, r *http.Request, uid int64, toNick, content string,
+) {
+	targetID, err := s.params.Database.LookupUserByNick(r.Context(), toNick)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "user not found"}, http.StatusNotFound)
+
 		return
 	}
+
 	msgID, err := s.params.Database.SendDM(r.Context(), uid, targetID, content)
 	if err != nil {
 		s.log.Error("send dm failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
-				s.respondJSON(w, r, map[string]any{"id": msgID, "status": "sent"}, http.StatusCreated)
-			}
 
-		case "JOIN":
+	s.respondJSON(w, r, map[string]any{"id": msgID, "status": "sent"}, http.StatusCreated)
-			if req.To == "" {
+}
+
+func (s *Handlers) handleJoinCommand(
+	w http.ResponseWriter, r *http.Request, uid int64, cmd *sendCommand,
+) {
+	if cmd.To == "" {
 		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
 		return
 	}
-			channel := req.To
+
+	channel := cmd.To
 	if !strings.HasPrefix(channel, "#") {
 		channel = "#" + channel
 	}
+
 	chID, err := s.params.Database.GetOrCreateChannel(r.Context(), channel)
 	if err != nil {
 		s.log.Error("get/create channel failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
-			if err := s.params.Database.JoinChannel(r.Context(), chID, uid); err != nil {
+
+	err = s.params.Database.JoinChannel(r.Context(), chID, uid)
+	if err != nil {
 		s.log.Error("join channel failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
-				return
-			}
-			s.respondJSON(w, r, map[string]string{"status": "joined", "channel": channel}, http.StatusOK)
 
-		case "PART":
-			if req.To == "" {
-				s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
 		return
 	}
-			channel := req.To
+
+	s.respondJSON(w, r, map[string]string{"status": "joined", "channel": channel}, http.StatusOK)
+}
+
+func (s *Handlers) handlePartCommand(
+	w http.ResponseWriter, r *http.Request, uid int64, cmd *sendCommand,
+) {
+	if cmd.To == "" {
+		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
+		return
+	}
+
+	channel := cmd.To
 	if !strings.HasPrefix(channel, "#") {
 		channel = "#" + channel
 	}
-			var chID int64
+
-			err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+	chID, err := s.lookupChannelID(r, channel)
-				"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
 	}
-			if err := s.params.Database.PartChannel(r.Context(), chID, uid); err != nil {
+
+	err = s.params.Database.PartChannel(r.Context(), chID, uid)
+	if err != nil {
 		s.log.Error("part channel failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
-			s.respondJSON(w, r, map[string]string{"status": "parted", "channel": channel}, http.StatusOK)
 
-		case "NICK":
+	s.respondJSON(w, r, map[string]string{"status": "parted", "channel": channel}, http.StatusOK)
-			lines := bodyLines()
+}
+
+func (s *Handlers) handleNickCommand(
+	w http.ResponseWriter, r *http.Request, uid int64, cmd *sendCommand,
+) {
+	lines := bodyLines(cmd.Body)
 	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 {
+	if newNick == "" || len(newNick) > maxNickLen {
 		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
 		}
+
 		s.log.Error("change nick failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
-				return
-			}
-			s.respondJSON(w, r, map[string]string{"status": "ok", "nick": newNick}, http.StatusOK)
 
-		case "TOPIC":
-			if req.To == "" {
-				s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
 		return
 	}
-			lines := bodyLines()
+
+	s.respondJSON(w, r, map[string]string{"status": "ok", "nick": newNick}, http.StatusOK)
+}
+
+func (s *Handlers) handleTopicCommand(
+	w http.ResponseWriter, r *http.Request, cmd *sendCommand,
+) {
+	if cmd.To == "" {
+		s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+
+		return
+	}
+
+	lines := bodyLines(cmd.Body)
 	if len(lines) == 0 {
 		s.respondJSON(w, r, map[string]string{"error": "body required (topic text)"}, http.StatusBadRequest)
+
 		return
 	}
+
 	topic := strings.Join(lines, " ")
-			channel := req.To
+
+	channel := cmd.To
 	if !strings.HasPrefix(channel, "#") {
 		channel = "#" + channel
 	}
-			if err := s.params.Database.SetTopic(r.Context(), channel, uid, topic); err != nil {
+
+	err := s.params.Database.SetTopic(r.Context(), channel, 0, topic)
+	if err != nil {
 		s.log.Error("set topic failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
+
 	s.respondJSON(w, r, map[string]string{"status": "ok", "topic": topic}, http.StatusOK)
-
-		case "PING":
-			s.respondJSON(w, r, map[string]string{"command": "PONG", "from": s.params.Config.ServerName}, http.StatusOK)
-
-		default:
-			_ = nick // suppress unused warning
-			s.respondJSON(w, r, map[string]string{"error": "unknown command: " + req.Command}, http.StatusBadRequest)
-		}
-	}
 }
 
 // HandleGetHistory returns message history for a specific target (channel or DM).
@@ -340,49 +467,84 @@ func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 		if !ok {
 			return
 		}
+
 		target := r.URL.Query().Get("target")
 		if target == "" {
 			s.respondJSON(w, r, map[string]string{"error": "target required"}, http.StatusBadRequest)
+
 			return
 		}
+
 		beforeID, _ := strconv.ParseInt(r.URL.Query().Get("before"), 10, 64)
+
 		limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
 		if limit <= 0 {
-			limit = 50
+			limit = defaultHistoryLimit
 		}
 
 		if strings.HasPrefix(target, "#") {
-			// Channel history
+			s.handleChannelHistory(w, r, target, beforeID, limit)
-			var chID int64
+		} else {
-			err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+			s.handleDMHistory(w, r, uid, target, beforeID, limit)
-				"SELECT id FROM channels WHERE name = ?", target).Scan(&chID)
+		}
+	}
+}
+
+const defaultHistoryLimit = 50
+
+func (s *Handlers) handleChannelHistory(
+	w http.ResponseWriter, r *http.Request,
+	target string, beforeID int64, limit int,
+) {
+	chID, err := s.lookupChannelID(r, target)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "channel not found"}, http.StatusNotFound)
+
 		return
 	}
+
 	msgs, err := s.params.Database.GetMessagesBefore(r.Context(), chID, beforeID, limit)
 	if err != nil {
 		s.log.Error("get history failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
+
 	s.respondJSON(w, r, msgs, http.StatusOK)
-		} else {
+}
-			// DM history
+
-			targetID, err := s.params.Database.GetUserByNick(r.Context(), target)
+func (s *Handlers) handleDMHistory(
+	w http.ResponseWriter, r *http.Request,
+	uid int64, target string, beforeID int64, limit int,
+) {
+	targetID, err := s.params.Database.LookupUserByNick(r.Context(), target)
 	if err != nil {
 		s.respondJSON(w, r, map[string]string{"error": "user not found"}, http.StatusNotFound)
+
 		return
 	}
+
 	msgs, err := s.params.Database.GetDMsBefore(r.Context(), uid, targetID, beforeID, limit)
 	if err != nil {
 		s.log.Error("get dm history failed", "error", err)
 		s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
+
 	s.respondJSON(w, r, msgs, http.StatusOK)
-		}
+}
-	}
+
+// lookupChannelID queries the channel ID by name using a parameterized query.
+func (s *Handlers) lookupChannelID(r *http.Request, name string) (int64, error) {
+	var chID int64
+
+	//nolint:gosec // query uses parameterized placeholder (?), not string interpolation
+	err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+		"SELECT id FROM channels WHERE name = ?", name).Scan(&chID)
+
+	return chID, err
 }
 
 // HandleServerInfo returns server metadata (MOTD, name).
@@ -391,6 +553,7 @@ func (s *Handlers) HandleServerInfo() http.HandlerFunc {
 		Name string `json:"name"`
 		MOTD string `json:"motd"`
 	}
+
 	return func(w http.ResponseWriter, r *http.Request) {
 		s.respondJSON(w, r, &response{
 			Name: s.params.Config.ServerName,

internal/models/auth_token.go

@@ -2,10 +2,13 @@ package models
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"time"
 )
 
+// ErrUserLookupNotAvailable is returned when user lookup is not configured.
+var ErrUserLookupNotAvailable = errors.New("user lookup not available")
+
 // AuthToken represents an authentication token for a user session.
 type AuthToken struct {
 	Base
@@ -19,9 +22,5 @@ type AuthToken struct {
 
 // User returns the user who owns this token.
 func (t *AuthToken) User(ctx context.Context) (*User, error) {
-	if ul := t.GetUserLookup(); ul != nil {
+	return t.LookupUser(ctx, t.UserID)
-		return ul.GetUserByID(ctx, t.UserID)
-	}
-
-	return nil, fmt.Errorf("user lookup not available")
 }

internal/models/channel_member.go

@@ -2,10 +2,13 @@ package models
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"time"
 )
 
+// ErrChannelLookupNotAvailable is returned when channel lookup is not configured.
+var ErrChannelLookupNotAvailable = errors.New("channel lookup not available")
+
 // ChannelMember represents a user's membership in a channel.
 type ChannelMember struct {
 	Base
@@ -19,18 +22,10 @@ type ChannelMember struct {
 
 // User returns the full User for this membership.
 func (cm *ChannelMember) User(ctx context.Context) (*User, error) {
-	if ul := cm.GetUserLookup(); ul != nil {
+	return cm.LookupUser(ctx, cm.UserID)
-		return ul.GetUserByID(ctx, cm.UserID)
-	}
-
-	return nil, fmt.Errorf("user lookup not available")
 }
 
 // Channel returns the full Channel for this membership.
 func (cm *ChannelMember) Channel(ctx context.Context) (*Channel, error) {
-	if cl := cm.GetChannelLookup(); cl != nil {
+	return cm.LookupChannel(ctx, cm.ChannelID)
-		return cl.GetChannelByID(ctx, cm.ChannelID)
-	}
-
-	return nil, fmt.Errorf("channel lookup not available")
 }

internal/models/model.go

@@ -39,20 +39,22 @@ func (b *Base) GetDB() *sql.DB {
 	return b.db.GetDB()
 }
 
-// GetUserLookup returns the DB as a UserLookup if it implements the interface.
+// LookupUser looks up a user by ID if the database supports it.
-func (b *Base) GetUserLookup() UserLookup {
+func (b *Base) LookupUser(ctx context.Context, id string) (*User, error) {
-	if ul, ok := b.db.(UserLookup); ok {
+	ul, ok := b.db.(UserLookup)
-		return ul
+	if !ok {
+		return nil, ErrUserLookupNotAvailable
 	}
 
-	return nil
+	return ul.GetUserByID(ctx, id)
 }
 
-// GetChannelLookup returns the DB as a ChannelLookup if it implements the interface.
+// LookupChannel looks up a channel by ID if the database supports it.
-func (b *Base) GetChannelLookup() ChannelLookup {
+func (b *Base) LookupChannel(ctx context.Context, id string) (*Channel, error) {
-	if cl, ok := b.db.(ChannelLookup); ok {
+	cl, ok := b.db.(ChannelLookup)
-		return cl
+	if !ok {
+		return nil, ErrChannelLookupNotAvailable
 	}
 
-	return nil
+	return cl.GetChannelByID(ctx, id)
 }

internal/models/session.go

@@ -2,7 +2,6 @@ package models
 
 import (
 	"context"
-	"fmt"
 	"time"
 )
 
@@ -19,9 +18,5 @@ type Session struct {
 
 // User returns the user who owns this session.
 func (s *Session) User(ctx context.Context) (*User, error) {
-	if ul := s.GetUserLookup(); ul != nil {
+	return s.LookupUser(ctx, s.UserID)
-		return ul.GetUserByID(ctx, s.UserID)
-	}
-
-	return nil, fmt.Errorf("user lookup not available")
 }

internal/server/routes.go

@@ -20,6 +20,13 @@ const routeTimeout = 60 * time.Second
 func (s *Server) SetupRoutes() {
 	s.router = chi.NewRouter()
 
+	s.setupMiddleware()
+	s.setupHealthAndMetrics()
+	s.setupAPIRoutes()
+	s.setupSPA()
+}
+
+func (s *Server) setupMiddleware() {
 	s.router.Use(middleware.Recoverer)
 	s.router.Use(middleware.RequestID)
 	s.router.Use(s.mw.Logging())
@@ -37,51 +44,63 @@ func (s *Server) SetupRoutes() {
 		})
 		s.router.Use(sentryHandler.Handle)
 	}
+}
 
-	// Health check
+func (s *Server) setupHealthAndMetrics() {
 	s.router.Get("/.well-known/healthcheck.json", s.h.HandleHealthCheck())
 
-	// Protected metrics endpoint
 	if viper.GetString("METRICS_USERNAME") != "" {
 		s.router.Group(func(r chi.Router) {
 			r.Use(s.mw.MetricsAuth())
 			r.Get("/metrics", http.HandlerFunc(promhttp.Handler().ServeHTTP))
 		})
 	}
+}
 
-	// API v1
+func (s *Server) setupAPIRoutes() {
 	s.router.Route("/api/v1", func(r chi.Router) {
 		r.Get("/server", s.h.HandleServerInfo())
 		r.Post("/session", s.h.HandleCreateSession())
 
-		// Unified state and message endpoints
 		r.Get("/state", s.h.HandleState())
 		r.Get("/messages", s.h.HandleGetMessages())
 		r.Post("/messages", s.h.HandleSendCommand())
 		r.Get("/history", s.h.HandleGetHistory())
 
-		// Channels
 		r.Get("/channels", s.h.HandleListAllChannels())
 		r.Get("/channels/{channel}/members", s.h.HandleChannelMembers())
 	})
+}
 
-	// Serve embedded SPA
+func (s *Server) setupSPA() {
 	distFS, err := fs.Sub(web.Dist, "dist")
 	if err != nil {
 		s.log.Error("failed to get web dist filesystem", "error", err)
-	} else {
+
+		return
+	}
+
 	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
+		readFS, ok := distFS.(fs.ReadFileFS)
-			f, err := distFS.(fs.ReadFileFS).ReadFile(r.URL.Path[1:])
+		if !ok {
-			if err != nil || len(f) == 0 {
+			http.NotFound(w, r)
-				indexHTML, _ := distFS.(fs.ReadFileFS).ReadFile("index.html")
+
+			return
+		}
+
+		f, readErr := readFS.ReadFile(r.URL.Path[1:])
+		if readErr != nil || len(f) == 0 {
+			indexHTML, _ := readFS.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)
 	})
-	}
 }