style: fix all golangci-lint issues and format code (refs #17)

Fix 380 lint violations across all Go source files including wsl_v5,
nlreturn, noinlineerr, errcheck, funlen, funcorder, tagliatelle,
perfsprint, modernize, revive, gosec, ireturn, mnd, forcetypeassert,
cyclop, and others.

Key changes:
- Split large handler/command functions into smaller methods
- Extract scan helpers for database queries
- Reorder exported/unexported methods per funcorder
- Add sentinel errors in models package
- Use camelCase JSON tags per tagliatelle defaults
- Add package comments
- Fix .gitignore to not exclude cmd/chat-cli directory

.gitignore

@@ -34,5 +34,5 @@ vendor/
 # Project
 data.db
 debug.log
-chat-cli
+/chat-cli
 web/node_modules/

cmd/chat-cli/api/client.go

@@ -1,15 +1,31 @@
+// Package api provides a client for the chat server HTTP API.
 package api
 
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
+	"strconv"
 	"time"
 )
 
+const (
+	httpTimeout      = 30 * time.Second
+	pollExtraDelay   = 5
+	httpErrThreshold = 400
+)
+
+// ErrHTTP is returned for non-2xx responses.
+var ErrHTTP = errors.New("http error")
+
+// ErrUnexpectedFormat is returned when the response format is
+// not recognised.
+var ErrUnexpectedFormat = errors.New("unexpected format")
+
 // Client wraps HTTP calls to the chat server API.
 type Client struct {
 	BaseURL    string
@@ -22,59 +38,32 @@ func NewClient(baseURL string) *Client {
 	return &Client{
 		BaseURL: baseURL,
 		HTTPClient: &http.Client{
-			Timeout: 30 * time.Second,
+			Timeout: httpTimeout,
 		},
 	}
 }
 
-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) {
+func (c *Client) CreateSession(
-	data, err := c.do("POST", "/api/v1/session", &SessionRequest{Nick: nick})
+	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
 }
 
@@ -84,78 +73,113 @@ 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) {
+func (c *Client) PollMessages(
-	// Use a longer HTTP timeout than the server long-poll timeout.
+	afterID string,
-	client := &http.Client{Timeout: time.Duration(timeout+5) * time.Second}
+	timeout int,
+) ([]Message, error) {
+	pollTimeout := time.Duration(
+		timeout+pollExtraDelay,
+	) * time.Second
+
+	client := &http.Client{Timeout: pollTimeout}
 
 	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.NewRequest( //nolint:noctx // CLI tool
+		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 from user config
 	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 >= httpErrThreshold {
-		return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(data))
+		return nil, fmt.Errorf(
+			"%w: %d: %s",
+			ErrHTTP, resp.StatusCode, string(data),
+		)
 	}
 
-	// The server may return an array directly or wrapped.
+	return decodeMessages(data)
+}
+
+func decodeMessages(data []byte) ([]Message, error) {
 	var msgs []Message
-	if err := json.Unmarshal(data, &msgs); err != nil {
-		// Try wrapped format.
-		var wrapped MessagesResponse
-		if err2 := json.Unmarshal(data, &wrapped); err2 != nil {
-			return nil, fmt.Errorf("decode messages: %w (raw: %s)", err, string(data))
-		}
-		msgs = wrapped.Messages
-	}
 
+	err := json.Unmarshal(data, &msgs)
+	if err == nil {
 		return msgs, nil
 	}
 
-// JoinChannel joins a channel via the unified command endpoint.
+	var wrapped MessagesResponse
-func (c *Client) JoinChannel(channel string) error {
+
-	return c.SendMessage(&Message{Command: "JOIN", To: channel})
+	err2 := json.Unmarshal(data, &wrapped)
+	if err2 != nil {
+		return nil, fmt.Errorf(
+			"decode messages: %w (raw: %s)",
+			err, string(data),
+		)
 	}
 
-// PartChannel leaves a channel via the unified command endpoint.
+	return wrapped.Messages, nil
+}
+
+// JoinChannel joins a channel via the unified command
+// endpoint.
+func (c *Client) JoinChannel(channel string) error {
+	return c.SendMessage(
+		&Message{Command: "JOIN", To: channel},
+	)
+}
+
+// PartChannel leaves a channel via the unified command
+// endpoint.
 func (c *Client) PartChannel(channel string) error {
-	return c.SendMessage(&Message{Command: "PART", To: channel})
+	return c.SendMessage(
+		&Message{Command: "PART", To: channel},
+	)
 }
 
 // ListChannels returns all channels on the server.
@@ -164,29 +188,39 @@ 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
 }
 
 // GetMembers returns members of a channel.
-func (c *Client) GetMembers(channel string) ([]string, error) {
+func (c *Client) GetMembers(
-	data, err := c.do("GET", "/api/v1/channels/"+url.PathEscape(channel)+"/members", nil)
+	channel string,
+) ([]string, error) {
+	path := "/api/v1/channels/" +
+		url.PathEscape(channel) + "/members"
+
+	data, err := c.do("GET", path, nil)
 	if err != nil {
 		return nil, err
 	}
+
 	var members []string
-	if err := json.Unmarshal(data, &members); err != nil {
+
-		// Try object format.
+	err = json.Unmarshal(data, &members)
-		var obj map[string]interface{}
+	if err != nil {
-		if err2 := json.Unmarshal(data, &obj); err2 != nil {
+		return nil, fmt.Errorf(
-			return nil, err
+			"%w: members: %s",
-		}
+			ErrUnexpectedFormat, string(data),
-		// Extract member names from whatever format.
+		)
-		return nil, fmt.Errorf("unexpected members format: %s", string(data))
 	}
+
 	return members, nil
 }
 
@@ -196,9 +230,63 @@ 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.NewRequest( //nolint:noctx // CLI tool
+		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) //nolint:gosec // URL from user config
+	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 >= httpErrThreshold {
+		return data, fmt.Errorf(
+			"%w: %d: %s",
+			ErrHTTP, resp.StatusCode, string(data),
+		)
+	}
+
+	return data, nil
+}

cmd/chat-cli/api/types.go

@@ -1,4 +1,4 @@
-package api
+package api //nolint:revive // package name is intentional
 
 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 +29,25 @@ 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).
+// 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 +61,7 @@ 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 +82,6 @@ func (m *Message) ParseTS() time.Time {
 	if err != nil {
 		return time.Now()
 	}
+
 	return t
 }

cmd/chat-cli/main.go

@@ -1,8 +1,10 @@
+// Package main implements chat-cli, an IRC-style terminal client.
 package main
 
 import (
 	"fmt"
 	"os"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -10,6 +12,12 @@ import (
 	"git.eeqj.de/sneak/chat/cmd/chat-cli/api"
 )
 
+const (
+	pollTimeoutSec = 15
+	retryDelay     = 2 * time.Second
+	maxNickLength  = 32
+)
+
 // App holds the application state.
 type App struct {
 	ui     *UI
@@ -32,11 +40,18 @@ func main() {
 	app.ui.OnInput(app.handleInput)
 	app.ui.SetStatus(app.nick, "", "disconnected")
 
-	app.ui.AddStatus("Welcome to chat-cli — an IRC-style client")
+	app.ui.AddStatus(
-	app.ui.AddStatus("Type [yellow]/connect <server-url>[white] to begin, or [yellow]/help[white] for commands")
+		"Welcome to chat-cli \u2014 an IRC-style client",
+	)
+	app.ui.AddStatus(
+		"Type [yellow]/connect <server-url>[white] " +
+			"to begin, or [yellow]/help[white] for commands",
+	)
+
+	err := app.ui.Run()
+	if err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 
-	if err := app.ui.Run(); err != nil {
-		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 		os.Exit(1)
 	}
 }
@@ -44,21 +59,34 @@ func main() {
 func (a *App) handleInput(text string) {
 	if strings.HasPrefix(text, "/") {
 		a.handleCommand(text)
+
 		return
 	}
 
-	// Plain text → PRIVMSG to current target.
+	a.sendPlainText(text)
+}
+
+func (a *App) sendPlainText(text string) {
 	a.mu.Lock()
 	target := a.target
 	connected := a.connected
+	nick := a.nick
 	a.mu.Unlock()
 
 	if !connected {
-		a.ui.AddStatus("[red]Not connected. Use /connect <url>")
+		a.ui.AddStatus(
+			"[red]Not connected. Use /connect <url>",
+		)
+
 		return
 	}
+
 	if target == "" {
-		a.ui.AddStatus("[red]No target. Use /join #channel or /query nick")
+		a.ui.AddStatus(
+			"[red]No target. " +
+				"Use /join #channel or /query nick",
+		)
+
 		return
 	}
 
@@ -68,21 +96,28 @@ func (a *App) handleInput(text string) {
 		Body:    []string{text},
 	})
 	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf("[red]Send error: %v", err))
+		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.ui.AddLine(
-	a.mu.Unlock()
+		target,
-	a.ui.AddLine(target, fmt.Sprintf("[gray]%s [green]<%s>[white] %s", ts, nick, text))
+		fmt.Sprintf(
+			"[gray]%s [green]<%s>[white] %s",
+			ts, nick, text,
+		),
+	)
 }
 
-func (a *App) handleCommand(text string) {
+func (a *App) handleCommand(text string) { //nolint:cyclop // command dispatch
-	parts := strings.SplitN(text, " ", 2)
+	parts := strings.SplitN(text, " ", 2) //nolint:mnd // split into cmd+args
 	cmd := strings.ToLower(parts[0])
+
 	args := ""
 	if len(parts) > 1 {
 		args = parts[1]
@@ -114,27 +149,41 @@ func (a *App) handleCommand(text string) {
 	case "/help":
 		a.cmdHelp()
 	default:
-		a.ui.AddStatus(fmt.Sprintf("[red]Unknown command: %s", cmd))
+		a.ui.AddStatus(
+			"[red]Unknown command: " + cmd,
+		)
 	}
 }
 
 func (a *App) cmdConnect(serverURL string) {
 	if serverURL == "" {
-		a.ui.AddStatus("[red]Usage: /connect <server-url>")
+		a.ui.AddStatus(
+			"[red]Usage: /connect <server-url>",
+		)
+
 		return
 	}
+
 	serverURL = strings.TrimRight(serverURL, "/")
 
-	a.ui.AddStatus(fmt.Sprintf("Connecting to %s...", serverURL))
+	a.ui.AddStatus(
+		fmt.Sprintf("Connecting to %s...", serverURL),
+	)
 
 	a.mu.Lock()
 	nick := a.nick
 	a.mu.Unlock()
 
 	client := api.NewClient(serverURL)
+
 	resp, err := client.CreateSession(nick)
 	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf("[red]Connection failed: %v", err))
+		a.ui.AddStatus(
+			fmt.Sprintf(
+				"[red]Connection failed: %v", err,
+			),
+		)
+
 		return
 	}
 
@@ -145,19 +194,26 @@ func (a *App) cmdConnect(serverURL string) {
 	a.lastMsgID = ""
 	a.mu.Unlock()
 
-	a.ui.AddStatus(fmt.Sprintf("[green]Connected! Nick: %s, Session: %s", resp.Nick, resp.SessionID))
+	a.ui.AddStatus(
+		fmt.Sprintf(
+			"[green]Connected! Nick: %s, Session: %s",
+			resp.Nick, resp.SessionID,
+		),
+	)
 	a.ui.SetStatus(resp.Nick, "", "connected")
 
-	// 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()
@@ -166,7 +222,14 @@ 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))
+
+		a.ui.AddStatus(
+			fmt.Sprintf(
+				"Nick set to %s (will be used on connect)",
+				nick,
+			),
+		)
+
 		return
 	}
 
@@ -175,7 +238,12 @@ func (a *App) cmdNick(nick string) {
 		Body:    []string{nick},
 	})
 	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf("[red]Nick change failed: %v", err))
+		a.ui.AddStatus(
+			fmt.Sprintf(
+				"[red]Nick change failed: %v", err,
+			),
+		)
+
 		return
 	}
 
@@ -183,15 +251,20 @@ 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 +272,19 @@ 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))
+		a.ui.AddStatus(
+			fmt.Sprintf("[red]Join failed: %v", err),
+		)
+
 		return
 	}
 
@@ -216,39 +294,55 @@ 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))
+		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()
 
@@ -257,19 +351,23 @@ func (a *App) cmdPart(channel string) {
 }
 
 func (a *App) cmdMsg(args string) {
-	parts := strings.SplitN(args, " ", 2)
+	parts := strings.SplitN(args, " ", 2) //nolint:mnd // split into target+text
-	if len(parts) < 2 {
+	if len(parts) < 2 {                   //nolint:mnd // min args
 		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
 	}
 
@@ -279,17 +377,28 @@ func (a *App) cmdMsg(args string) {
 		Body:    []string{text},
 	})
 	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf("[red]Send failed: %v", err))
+		a.ui.AddStatus(
+			fmt.Sprintf("[red]Send failed: %v", err),
+		)
+
 		return
 	}
 
 	ts := time.Now().Format("15:04")
-	a.ui.AddLine(target, fmt.Sprintf("[gray]%s [green]<%s>[white] %s", ts, nick, text))
+
+	a.ui.AddLine(
+		target,
+		fmt.Sprintf(
+			"[gray]%s [green]<%s>[white] %s",
+			ts, nick, text,
+		),
+	)
 }
 
 func (a *App) cmdQuery(nick string) {
 	if nick == "" {
 		a.ui.AddStatus("[red]Usage: /query <nick>")
+
 		return
 	}
 
@@ -310,22 +419,29 @@ 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{
 			Command: "TOPIC",
 			To:      target,
 		})
 		if err != nil {
-			a.ui.AddStatus(fmt.Sprintf("[red]Topic query failed: %v", err))
+			a.ui.AddStatus(
+				fmt.Sprintf(
+					"[red]Topic query failed: %v", err,
+				),
+			)
 		}
+
 		return
 	}
 
@@ -335,7 +451,11 @@ func (a *App) cmdTopic(args string) {
 		Body:    []string{args},
 	})
 	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf("[red]Topic set failed: %v", err))
+		a.ui.AddStatus(
+			fmt.Sprintf(
+				"[red]Topic set failed: %v", err,
+			),
+		)
 	}
 }
 
@@ -347,20 +467,32 @@ 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))
+		a.ui.AddStatus(
+			fmt.Sprintf("[red]Names failed: %v", err),
+		)
+
 		return
 	}
 
-	a.ui.AddLine(target, fmt.Sprintf("[cyan]*** Members of %s: %s", target, strings.Join(members, " ")))
+	a.ui.AddLine(
+		target,
+		fmt.Sprintf(
+			"[cyan]*** Members of %s: %s",
+			target, strings.Join(members, " "),
+		),
+	)
 }
 
 func (a *App) cmdList() {
@@ -370,46 +502,55 @@ 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))
+		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(
+			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)
+	n, _ := strconv.Atoi(args)
 	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 >= 0 && n < a.ui.BufferCount() {
-	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 +560,17 @@ 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(
+			&api.Message{Command: "QUIT"},
+		)
 	}
+
 	if a.stopPoll != nil {
 		close(a.stopPoll)
 	}
+
 	a.mu.Unlock()
 	a.ui.Stop()
 }
@@ -432,20 +578,21 @@ func (a *App) cmdQuit() {
 func (a *App) cmdHelp() {
 	help := []string{
 		"[cyan]*** chat-cli commands:",
-		"  /connect <url>  — Connect to server",
+		"  /connect <url>  \u2014 Connect to server",
-		"  /nick <name>    — Change nickname",
+		"  /nick <name>    \u2014 Change nickname",
-		"  /join #channel  — Join channel",
+		"  /join #channel  \u2014 Join channel",
-		"  /part [#chan]    — Leave channel",
+		"  /part [#chan]    \u2014 Leave channel",
-		"  /msg <nick> <text> — Send DM",
+		"  /msg <nick> <text> \u2014 Send DM",
-		"  /query <nick>   — Open DM window",
+		"  /query <nick>   \u2014 Open DM window",
-		"  /topic [text]   — View/set topic",
+		"  /topic [text]   \u2014 View/set topic",
-		"  /names          — List channel members",
+		"  /names          \u2014 List channel members",
-		"  /list           — List channels",
+		"  /list           \u2014 List channels",
-		"  /window <n>     — Switch buffer (Alt+0-9)",
+		"  /window <n>     \u2014 Switch buffer (Alt+0-9)",
-		"  /quit           — Disconnect and exit",
+		"  /quit           \u2014 Disconnect and exit",
-		"  /help           — This help",
+		"  /help           \u2014 This help",
 		"  Plain text sends to current target.",
 	}
+
 	for _, line := range help {
 		a.ui.AddStatus(line)
 	}
@@ -469,32 +616,31 @@ 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(retryDelay)
-			time.Sleep(2 * time.Second)
+
 			continue
 		}
 
-		for _, msg := range msgs {
+		for i := range msgs {
-			a.handleServerMessage(&msg)
+			a.handleServerMessage(&msgs[i])
-			if msg.ID != "" {
+
+			if msgs[i].ID != "" {
 				a.mu.Lock()
-				a.lastMsgID = msg.ID
+				a.lastMsgID = msgs[i].ID
 				a.mu.Unlock()
 			}
 		}
 	}
 }
 
-func (a *App) handleServerMessage(msg *api.Message) {
+func (a *App) handleServerMessage(
-	ts := ""
+	msg *api.Message,
-	if msg.TS != "" {
+) {
-		t := msg.ParseTS()
+	ts := a.parseMessageTS(msg)
-		ts = t.Local().Format("15:04")
-	} else {
-		ts = time.Now().Format("15:04")
-	}
 
 	a.mu.Lock()
 	myNick := a.nick
@@ -502,79 +648,203 @@ func (a *App) handleServerMessage(msg *api.Message) {
 
 	switch msg.Command {
 	case "PRIVMSG":
+		a.handlePrivmsgMsg(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) parseMessageTS(msg *api.Message) string {
+	if msg.TS != "" {
+		t := msg.ParseTS()
+
+		return t.In(time.Local).Format("15:04") //nolint:gosmopolitan // CLI uses local time
+	}
+
+	return time.Now().Format("15:04")
+}
+
+func (a *App) handlePrivmsgMsg(
+	msg *api.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 := msg.To
+		target,
-		if target != "" {
+		fmt.Sprintf(
-			a.ui.AddLine(target, fmt.Sprintf("[gray]%s [yellow]*** %s has joined %s", ts, msg.From, target))
+			"[gray]%s [green]<%s>[white] %s",
+			ts, msg.From, text,
+		),
+	)
 }
 
-	case "PART":
+func (a *App) handleJoinMsg(
+	msg *api.Message, ts string,
+) {
 	target := msg.To
+	if target == "" {
+		return
+	}
+
+	a.ui.AddLine(
+		target,
+		fmt.Sprintf(
+			"[gray]%s [yellow]*** %s has joined %s",
+			ts, msg.From, target,
+		),
+	)
+}
+
+func (a *App) handlePartMsg(
+	msg *api.Message, ts string,
+) {
+	target := msg.To
+	if target == "" {
+		return
+	}
+
 	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))
+		a.ui.AddLine(
+			target,
+			fmt.Sprintf(
+				"[gray]%s [yellow]*** %s has left %s (%s)",
+				ts, msg.From, target, reason,
+			),
+		)
 	} else {
-				a.ui.AddLine(target, fmt.Sprintf("[gray]%s [yellow]*** %s has left %s", ts, msg.From, target))
+		a.ui.AddLine(
+			target,
+			fmt.Sprintf(
+				"[gray]%s [yellow]*** %s has left %s",
+				ts, msg.From, target,
+			),
+		)
 	}
 }
 
-	case "QUIT":
+func (a *App) handleQuitMsg(
+	msg *api.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))
+		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))
+		a.ui.AddStatus(
+			fmt.Sprintf(
+				"[gray]%s [yellow]*** %s has quit",
+				ts, msg.From,
+			),
+		)
+	}
 }
 
-	case "NICK":
+func (a *App) handleNickMsg(
+	msg *api.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":
+	a.ui.AddStatus(
-		lines := msg.BodyLines()
+		fmt.Sprintf(
-		text := strings.Join(lines, " ")
+			"[gray]%s [yellow]*** %s is now known as %s",
-		a.ui.AddStatus(fmt.Sprintf("[gray]%s [magenta]--%s-- %s", ts, msg.From, text))
+			ts, msg.From, newNick,
-
+		),
-	case "TOPIC":
+	)
-		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) handleNoticeMsg(
-		// Numeric replies and other messages → status window.
+	msg *api.Message, ts string,
+) {
 	lines := msg.BodyLines()
 	text := strings.Join(lines, " ")
-		if text != "" {
+
-			a.ui.AddStatus(fmt.Sprintf("[gray]%s [white][%s] %s", ts, msg.Command, text))
+	a.ui.AddStatus(
+		fmt.Sprintf(
+			"[gray]%s [magenta]--%s-- %s",
+			ts, msg.From, text,
+		),
+	)
 }
+
+func (a *App) handleTopicMsg(
+	msg *api.Message, ts string,
+) {
+	if msg.To == "" {
+		return
 	}
+
+	lines := msg.BodyLines()
+	text := strings.Join(lines, " ")
+
+	a.ui.AddLine(
+		msg.To,
+		fmt.Sprintf(
+			"[gray]%s [cyan]*** %s set topic: %s",
+			ts, msg.From, text,
+		),
+	)
+}
+
+func (a *App) handleDefaultMsg(
+	msg *api.Message, ts string,
+) {
+	lines := msg.BodyLines()
+	text := strings.Join(lines, " ")
+
+	if text == "" {
+		return
+	}
+
+	a.ui.AddStatus(
+		fmt.Sprintf(
+			"[gray]%s [white][%s] %s",
+			ts, msg.Command, text,
+		),
+	)
 }

cmd/chat-cli/ui.go

@@ -31,6 +31,7 @@ type UI struct {
 }
 
 // NewUI creates the tview-based IRC-like UI.
+
 func NewUI() *UI {
 	ui := &UI{
 		app: tview.NewApplication(),
@@ -39,80 +40,35 @@ func NewUI() *UI {
 		},
 	}
 
-	// Message area.
+	ui.setupMessages()
-	ui.messages = tview.NewTextView().
+	ui.setupStatusBar()
-		SetDynamicColors(true).
+	ui.setupInput()
-		SetScrollable(true).
+	ui.setupKeybindings()
-		SetWordWrap(true).
+	ui.setupLayout()
-		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
 }
 
 // Run starts the UI event loop (blocks).
+
 func (ui *UI) Run() error {
 	return ui.app.Run()
 }
 
 // Stop stops the UI.
+
 func (ui *UI) Stop() {
 	ui.app.Stop()
 }
 
 // OnInput sets the callback for user input.
+
 func (ui *UI) OnInput(fn func(string)) {
 	ui.onInput = fn
 }
 
 // AddLine adds a line to the specified buffer.
+
 func (ui *UI) AddLine(bufferName string, line string) {
 	ui.app.QueueUpdateDraw(func() {
 		buf := ui.getOrCreateBuffer(bufferName)
@@ -121,89 +77,219 @@ 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)
 		}
 	})
 }
 
 // AddStatus adds a line to the status buffer (buffer 0).
+
 func (ui *UI) AddStatus(line string) {
 	ts := time.Now().Format("15:04")
-	ui.AddLine("(status)", fmt.Sprintf("[gray]%s[white] %s", ts, line))
+
+	ui.AddLine(
+		"(status)",
+		fmt.Sprintf("[gray]%s[white] %s", ts, line),
+	)
 }
 
 // SwitchBuffer switches to the buffer at index n.
+
 func (ui *UI) SwitchBuffer(n int) {
 	ui.app.QueueUpdateDraw(func() {
 		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()
 	})
 }
 
-// SwitchToBuffer switches to the named buffer, creating it if needed.
+// SwitchToBuffer switches to the named buffer, creating it
+
 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()
 	})
 }
 
 // SetStatus updates the status bar text.
-func (ui *UI) SetStatus(nick, target, connStatus string) {
+
+func (ui *UI) SetStatus(
+	nick, target, connStatus string,
+) {
 	ui.app.QueueUpdateDraw(func() {
 		ui.refreshStatusWith(nick, target, connStatus)
 	})
 }
 
-func (ui *UI) refreshStatus() {
+// BufferCount returns the number of buffers.
-	// Will be called from the main goroutine via QueueUpdateDraw parent.
+
-	// Rebuild status from app state — caller must provide context.
+func (ui *UI) BufferCount() int {
+	return len(ui.buffers)
 }
 
-func (ui *UI) refreshStatusWith(nick, target, connStatus string) {
+// BufferIndex returns the index of a named buffer, or -1.
+
+func (ui *UI) BufferIndex(name string) int {
+	for i, buf := range ui.buffers {
+		if buf.Name == name {
+			return i
+		}
+	}
+
+	return -1
+}
+
+func (ui *UI) setupMessages() {
+	ui.messages = tview.NewTextView().
+		SetDynamicColors(true).
+		SetScrollable(true).
+		SetWordWrap(true).
+		SetChangedFunc(func() {
+			ui.app.Draw()
+		})
+	ui.messages.SetBorder(false)
+}
+
+func (ui *UI) setupStatusBar() {
+	ui.statusBar = tview.NewTextView().
+		SetDynamicColors(true)
+	ui.statusBar.SetBackgroundColor(tcell.ColorNavy)
+	ui.statusBar.SetTextColor(tcell.ColorWhite)
+}
+
+func (ui *UI) setupInput() {
+	ui.input = tview.NewInputField().
+		SetFieldBackgroundColor(tcell.ColorBlack).
+		SetFieldTextColor(tcell.ColorWhite)
+
+	ui.input.SetDoneFunc(func(key tcell.Key) {
+		if key != tcell.KeyEnter {
+			return
+		}
+
+		text := ui.input.GetText()
+		if text == "" {
+			return
+		}
+
+		ui.input.SetText("")
+
+		if ui.onInput != nil {
+			ui.onInput(text)
+		}
+	})
+}
+
+func (ui *UI) setupKeybindings() {
+	ui.app.SetInputCapture(
+		func(event *tcell.EventKey) *tcell.EventKey {
+			if event.Modifiers()&tcell.ModAlt == 0 {
+				return event
+			}
+
+			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)
+}
+
+// if needed.
+
+func (ui *UI) refreshStatus() {
+	// Rebuilt from app state by parent QueueUpdateDraw.
+}
+
+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))
+			unreadParts = append(
+				unreadParts,
+				fmt.Sprintf(
+					"%d:%s(%d)", i, buf.Name, buf.Unread,
+				),
+			)
 		}
 	}
+
 	unread := ""
 	if len(unreadParts) > 0 {
-		unread = " [Act: " + strings.Join(unreadParts, ",") + "]"
+		unread = " [Act: " +
+			strings.Join(unreadParts, ",") + "]"
 	}
 
-	bufInfo := fmt.Sprintf("[%d:%s]", ui.currentBuffer, ui.buffers[ui.currentBuffer].Name)
+	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)
+	_, _ = fmt.Fprintf(
+		ui.statusBar, " [%s] %s %s %s%s",
+		connStatus, nick, bufInfo, target, unread,
+	)
 }
 
 func (ui *UI) getOrCreateBuffer(name string) *Buffer {
@@ -212,22 +298,9 @@ func (ui *UI) getOrCreateBuffer(name string) *Buffer {
 			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)
-}
-
-// BufferIndex returns the index of a named buffer, or -1.
-func (ui *UI) BufferIndex(name string) int {
-	for i, buf := range ui.buffers {
-		if buf.Name == name {
-			return i
-		}
-	}
-	return -1
-}

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.Exec("PRAGMA foreign_keys = ON") //nolint:noctx // no context in sql.Open path
+	if err != nil {
 		_ = d.Close()
+
 		return nil, fmt.Errorf("enable foreign keys: %w", err)
 	}
 
@@ -162,7 +164,7 @@ func (s *Database) GetChannelByID(
 	return c, nil
 }
 
-// GetUserByNick looks up a user by their nick.
+// GetUserByNickModel looks up a user by their nick.
 func (s *Database) GetUserByNickModel(
 	ctx context.Context,
 	nick string,
@@ -185,7 +187,7 @@ func (s *Database) GetUserByNickModel(
 	return u, nil
 }
 
-// GetUserByToken looks up a user by their auth token.
+// GetUserByTokenModel looks up a user by their auth token.
 func (s *Database) GetUserByTokenModel(
 	ctx context.Context,
 	token string,
@@ -219,6 +221,7 @@ func (s *Database) DeleteAuthToken(
 	_, err := s.db.ExecContext(ctx,
 		`DELETE FROM auth_tokens WHERE token = ?`, token,
 	)
+
 	return err
 }
 
@@ -231,10 +234,11 @@ func (s *Database) UpdateUserLastSeen(
 		`UPDATE users SET last_seen_at = CURRENT_TIMESTAMP WHERE id = ?`,
 		userID,
 	)
+
 	return err
 }
 
-// CreateUser inserts a new user into the database.
+// CreateUserModel inserts a new user into the database.
 func (s *Database) CreateUserModel(
 	ctx context.Context,
 	id, nick, passwordHash string,
@@ -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 // placeholders are ?, 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)
 	}
 
@@ -676,6 +682,19 @@ func (s *Database) applyMigrations(
 			"version", m.version, "name", m.name,
 		)
 
+		err = s.executeMigration(ctx, m)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (s *Database) executeMigration(
+	ctx context.Context,
+	m migration,
+) error {
 	tx, err := s.db.BeginTx(ctx, nil)
 	if err != nil {
 		return fmt.Errorf(
@@ -705,12 +724,12 @@ 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

@@ -3,107 +3,144 @@ package db
 import (
 	"context"
 	"crypto/rand"
+	"database/sql"
 	"encoding/hex"
 	"fmt"
 	"time"
 )
 
+const (
+	defaultMessageLimit = 50
+	defaultPollLimit    = 100
+	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.
+// CreateUser registers a new user with the given nick and
-func (s *Database) CreateUser(ctx context.Context, nick string) (int64, string, error) {
+// returns the user with token.
+func (s *Database) CreateUser(
+	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.
+// GetUserByToken returns user id and nick for a given auth
-func (s *Database) GetUserByToken(ctx context.Context, token string) (int64, string, error) {
+// token.
+func (s *Database) GetUserByToken(
+	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)
+
+	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)
+	_, _ = 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.
-func (s *Database) GetUserByNick(ctx context.Context, nick string) (int64, error) {
+func (s *Database) GetUserByNick(
+	ctx context.Context,
+	nick string,
+) (int64, error) {
 	var id int64
-	err := s.db.QueryRowContext(ctx, "SELECT id FROM users WHERE nick = ?", nick).Scan(&id)
+
+	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.
+// GetOrCreateChannel returns the channel id, creating it if
-func (s *Database) GetOrCreateChannel(ctx context.Context, name string) (int64, error) {
+// 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)
+
+	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
 }
 
 // JoinChannel adds a user to a channel.
-func (s *Database) JoinChannel(ctx context.Context, channelID, userID int64) error {
+func (s *Database) JoinChannel(
+	ctx context.Context,
+	channelID, userID int64,
+) error {
 	_, err := s.db.ExecContext(ctx,
 		"INSERT OR IGNORE INTO channel_members (channel_id, user_id, joined_at) VALUES (?, ?, ?)",
 		channelID, userID, time.Now())
+
 	return err
 }
 
 // PartChannel removes a user from a channel.
-func (s *Database) PartChannel(ctx context.Context, channelID, userID int64) error {
+func (s *Database) PartChannel(
+	ctx context.Context,
+	channelID, userID int64,
+) error {
 	_, err := s.db.ExecContext(ctx,
 		"DELETE FROM channel_members WHERE channel_id = ? AND user_id = ?",
 		channelID, userID)
-	return err
-}
 
-// ListChannels returns all channels the user has joined.
+	return err
-func (s *Database) ListChannels(ctx context.Context, userID int64) ([]ChannelInfo, error) {
-	rows, err := s.db.QueryContext(ctx,
-		`SELECT c.id, c.name, c.topic FROM channels c
-		 INNER JOIN channel_members cm ON cm.channel_id = c.id
-		 WHERE cm.user_id = ? ORDER BY c.name`, userID)
-	if err != nil {
-		return nil, err
-	}
-	defer 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
-		}
-		channels = append(channels, ch)
-	}
-	if channels == nil {
-		channels = []ChannelInfo{}
-	}
-	return channels, nil
 }
 
 // ChannelInfo is a lightweight channel representation.
@@ -113,28 +150,44 @@ type ChannelInfo struct {
 	Topic string `json:"topic"`
 }
 
-// ChannelMembers returns all members of a channel.
+// ListChannels returns all channels the user has joined.
-func (s *Database) ChannelMembers(ctx context.Context, channelID int64) ([]MemberInfo, error) {
+func (s *Database) ListChannels(
+	ctx context.Context,
+	userID int64,
+) ([]ChannelInfo, error) {
 	rows, err := s.db.QueryContext(ctx,
-		`SELECT u.id, u.nick, u.last_seen FROM users u
+		`SELECT c.id, c.name, c.topic FROM channels c
-		 INNER JOIN channel_members cm ON cm.user_id = u.id
+		 INNER JOIN channel_members cm ON cm.channel_id = c.id
-		 WHERE cm.channel_id = ? ORDER BY u.nick`, channelID)
+		 WHERE cm.user_id = ? ORDER BY c.name`, userID)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var members []MemberInfo
+	defer func() { _ = rows.Close() }()
+
+	var channels []ChannelInfo
+
 	for rows.Next() {
-		var m MemberInfo
+		var ch ChannelInfo
-		if err := rows.Scan(&m.ID, &m.Nick, &m.LastSeen); err != nil {
+
+		err := rows.Scan(&ch.ID, &ch.Name, &ch.Topic)
+		if err != nil {
 			return nil, err
 		}
-		members = append(members, m)
+
+		channels = append(channels, ch)
 	}
-	if members == nil {
+
-		members = []MemberInfo{}
+	err = rows.Err()
+	if err != nil {
+		return nil, err
 	}
-	return members, nil
+
+	if channels == nil {
+		channels = []ChannelInfo{}
+	}
+
+	return channels, nil
 }
 
 // MemberInfo represents a channel member.
@@ -144,6 +197,46 @@ type MemberInfo struct {
 	LastSeen time.Time `json:"lastSeen"`
 }
 
+// ChannelMembers returns all members of a channel.
+func (s *Database) ChannelMembers(
+	ctx context.Context,
+	channelID int64,
+) ([]MemberInfo, error) {
+	rows, err := s.db.QueryContext(ctx,
+		`SELECT u.id, u.nick, u.last_seen FROM users u
+		 INNER JOIN channel_members cm ON cm.user_id = u.id
+		 WHERE cm.channel_id = ? ORDER BY u.nick`, channelID)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var members []MemberInfo
+
+	for rows.Next() {
+		var m MemberInfo
+
+		err := rows.Scan(&m.ID, &m.Nick, &m.LastSeen)
+		if err != nil {
+			return nil, err
+		}
+
+		members = append(members, m)
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	if members == nil {
+		members = []MemberInfo{}
+	}
+
+	return members, nil
+}
+
 // MessageInfo represents a chat message.
 type MessageInfo struct {
 	ID        int64     `json:"id"`
@@ -155,11 +248,18 @@ type MessageInfo struct {
 	CreatedAt time.Time `json:"createdAt"`
 }
 
-// GetMessages returns messages for a channel, optionally after a given ID.
+// GetMessages returns messages for a channel, optionally
-func (s *Database) GetMessages(ctx context.Context, channelID int64, afterID int64, limit int) ([]MessageInfo, error) {
+// after a given ID.
+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
@@ -170,128 +270,288 @@ func (s *Database) GetMessages(ctx context.Context, channelID int64, afterID int
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
+	defer func() { _ = rows.Close() }()
+
 	var msgs []MessageInfo
+
 	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
 		}
+
 		msgs = append(msgs, m)
 	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
 	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.
+// GetDMs returns direct messages between two users after a
-func (s *Database) GetDMs(ctx context.Context, userA, userB int64, afterID int64, limit int) ([]MessageInfo, error) {
+// given ID.
+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
 		 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 = ?))
+		 AND ((m.user_id = ? AND m.dm_target_id = ?)
-		 ORDER BY m.id ASC LIMIT ?`, afterID, userA, userB, userB, userA, limit)
+		   OR (m.user_id = ? AND m.dm_target_id = ?))
+		 ORDER BY m.id ASC LIMIT ?`,
+		afterID, userA, userB, userB, userA, limit)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
+	defer func() { _ = rows.Close() }()
+
 	var msgs []MessageInfo
+
 	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
 		}
+
 		m.IsDM = true
+
 		msgs = append(msgs, m)
 	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
 	if msgs == nil {
 		msgs = []MessageInfo{}
 	}
+
 	return msgs, nil
 }
 
-// PollMessages returns all new messages (channel + DM) for a user after a given ID.
+// PollMessages returns all new messages (channel + DM) for
-func (s *Database) PollMessages(ctx context.Context, userID int64, afterID int64, limit int) ([]MessageInfo, error) {
+// a user after a given ID.
+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
-		   OR (m.is_dm = 1 AND (m.user_id = ? OR m.dm_target_id = ?))
+		     (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)
+		 ORDER BY m.id ASC LIMIT ?`,
+		afterID, userID, userID, userID, limit)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	defer func() { _ = rows.Close() }()
+
+	msgs := make([]MessageInfo, 0)
+
 	for rows.Next() {
-		var m MessageInfo
+		var (
-		var isDM int
+			m    MessageInfo
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &isDM, &m.DMTarget, &m.CreatedAt); err != nil {
+			isDM int
+		)
+
+		err := rows.Scan(
+			&m.ID, &m.Channel, &m.Nick, &m.Content,
+			&isDM, &m.DMTarget, &m.CreatedAt,
+		)
+		if err != nil {
 			return nil, err
 		}
+
 		m.IsDM = isDM == 1
 		msgs = append(msgs, m)
 	}
-	if msgs == nil {
+
-		msgs = []MessageInfo{}
+	err = rows.Err()
+	if err != nil {
+		return nil, err
 	}
+
 	return msgs, nil
 }
 
-// GetMessagesBefore returns channel messages before a given ID (for history scrollback).
+func scanChannelMessages(
-func (s *Database) GetMessagesBefore(ctx context.Context, channelID int64, beforeID int64, limit int) ([]MessageInfo, error) {
+	rows *sql.Rows,
-	if limit <= 0 {
+) ([]MessageInfo, error) {
-		limit = 50
+	var msgs []MessageInfo
+
+	for rows.Next() {
+		var m MessageInfo
+
+		err := rows.Scan(
+			&m.ID, &m.Channel, &m.Nick,
+			&m.Content, &m.CreatedAt,
+		)
+		if err != nil {
+			return nil, err
 		}
+
+		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) {
+	var msgs []MessageInfo
+
+	for rows.Next() {
+		var m MessageInfo
+
+		err := rows.Scan(
+			&m.ID, &m.Nick, &m.Content,
+			&m.DMTarget, &m.CreatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		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 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]
+	}
+}
+
+// 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) {
+	if limit <= 0 {
+		limit = defaultMessageLimit
+	}
+
 	var query string
+
 	var args []any
+
 	if beforeID > 0 {
-		query = `SELECT m.id, c.name, u.nick, m.content, m.created_at
+		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 < ?
+			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
+		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
@@ -299,116 +559,153 @@ func (s *Database) GetMessagesBefore(ctx context.Context, channelID int64, befor
 			ORDER BY m.id DESC LIMIT ?`
 		args = []any{channelID, limit}
 	}
+
 	rows, err := s.db.QueryContext(ctx, query, args...)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	defer func() { _ = rows.Close() }()
-	for rows.Next() {
+
-		var m MessageInfo
+	msgs, scanErr := scanChannelMessages(rows)
-		if err := rows.Scan(&m.ID, &m.Channel, &m.Nick, &m.Content, &m.CreatedAt); err != nil {
+	if scanErr != nil {
-			return nil, err
+		return nil, scanErr
-		}
-		msgs = append(msgs, m)
-	}
-	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]
 	}
+
+	// Reverse to ascending order.
+	reverseMessages(msgs)
+
 	return msgs, nil
 }
 
-// GetDMsBefore returns DMs between two users before a given ID (for history scrollback).
+// GetDMsBefore returns DMs between two users before a given
-func (s *Database) GetDMsBefore(ctx context.Context, userA, userB int64, beforeID int64, limit int) ([]MessageInfo, error) {
+// ID (for history scrollback).
+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
+		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 = ?))
+			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}
+		args = []any{
+			beforeID, userA, userB, userB, userA, limit,
+		}
 	} else {
-		query = `SELECT m.id, u.nick, m.content, t.nick, m.created_at
+		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 = ?))
+			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}
 	}
+
 	rows, err := s.db.QueryContext(ctx, query, args...)
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
-	var msgs []MessageInfo
+	defer func() { _ = rows.Close() }()
-	for rows.Next() {
+
-		var m MessageInfo
+	msgs, scanErr := scanDMMessages(rows)
-		if err := rows.Scan(&m.ID, &m.Nick, &m.Content, &m.DMTarget, &m.CreatedAt); err != nil {
+	if scanErr != nil {
-			return nil, err
+		return nil, scanErr
-		}
-		m.IsDM = true
-		msgs = append(msgs, m)
-	}
-	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]
 	}
+
+	// Reverse to ascending order.
+	reverseMessages(msgs)
+
 	return msgs, nil
 }
 
 // ChangeNick updates a user's nickname.
-func (s *Database) ChangeNick(ctx context.Context, userID int64, newNick string) error {
+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)
+		"UPDATE users SET nick = ? WHERE id = ?",
+		newNick, userID)
+
 	return err
 }
 
 // SetTopic sets the topic for a channel.
-func (s *Database) SetTopic(ctx context.Context, channelName string, _ int64, topic string) error {
+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)
+		"UPDATE channels SET topic = ? WHERE name = ?",
+		topic, channelName)
+
 	return err
 }
 
-// GetServerName returns the server name (unused, config provides this).
+// GetServerName returns the server name (unused, config
+// provides this).
 func (s *Database) GetServerName() string {
 	return ""
 }
 
 // ListAllChannels returns all channels.
-func (s *Database) ListAllChannels(ctx context.Context) ([]ChannelInfo, error) {
+func (s *Database) ListAllChannels(
+	ctx context.Context,
+) ([]ChannelInfo, error) {
 	rows, err := s.db.QueryContext(ctx,
 		"SELECT id, name, topic FROM channels ORDER BY name")
 	if err != nil {
 		return nil, err
 	}
-	defer rows.Close()
+
+	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 {
+
+		err := rows.Scan(
+			&ch.ID, &ch.Name, &ch.Topic,
+		)
+		if err != nil {
 			return nil, err
 		}
+
 		channels = append(channels, ch)
 	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
 	if channels == nil {
 		channels = []ChannelInfo{}
 	}
+
 	return channels, nil
 }

internal/handlers/api.go

@@ -11,79 +11,181 @@ import (
 	"github.com/go-chi/chi"
 )
 
-// authUser extracts the user from the Authorization header (Bearer token).
+const (
-func (s *Handlers) authUser(r *http.Request) (int64, string, error) {
+	maxNickLen     = 32
+	defaultHistory = 50
+)
+
+// 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)
 }
 
-func (s *Handlers) requireAuth(w http.ResponseWriter, r *http.Request) (int64, string, bool) {
+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)
+		s.respondJSON(
+			w, r,
+			map[string]string{"error": "unauthorized"},
+			http.StatusUnauthorized,
+		)
+
 		return 0, "", false
 	}
+
 	return uid, nick, true
 }
 
-// HandleCreateSession creates a new user session and returns the auth token.
+func (s *Handlers) respondError(
+	w http.ResponseWriter,
+	r *http.Request,
+	msg string,
+	code int,
+) {
+	s.respondJSON(w, r, map[string]string{"error": msg}, code)
+}
+
+func (s *Handlers) internalError(
+	w http.ResponseWriter,
+	r *http.Request,
+	msg string,
+	err error,
+) {
+	s.log.Error(msg, "error", err)
+	s.respondError(w, r, "internal error", http.StatusInternalServerError)
+}
+
+// bodyLines extracts body as string lines from a request body
+// field.
+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 {
+				lines = append(lines, s)
+			}
+		}
+
+		return lines
+	case []string:
+		return v
+	default:
+		return nil
+	}
+}
+
+// HandleCreateSession creates a new user session and returns
+// the auth token.
 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 {
+
-			s.respondJSON(w, r, map[string]string{"error": "invalid request"}, http.StatusBadRequest)
+		err := json.NewDecoder(r.Body).Decode(&req)
+		if err != nil {
+			s.respondError(
+				w, r, "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)
+		if req.Nick == "" || len(req.Nick) > maxNickLen {
+			s.respondError(
+				w, r, "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.CreateUser(
+			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)
+				s.respondError(
+					w, r, "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)
+			s.internalError(w, r, "create user failed", err)
+
 			return
 		}
-		s.respondJSON(w, r, &response{ID: id, Nick: req.Nick, Token: token}, http.StatusCreated)
+
+		s.respondJSON(
+			w, r,
+			&response{ID: id, Nick: req.Nick, Token: token},
+			http.StatusCreated,
+		)
 	}
 }
 
-// HandleState returns the current user's info and joined channels.
+// HandleState returns the current user's info and joined
+// channels.
 func (s *Handlers) HandleState() http.HandlerFunc {
 	type response struct {
 		ID       int64            `json:"id"`
 		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)
+
+		channels, err := s.params.Database.ListChannels(
+			r.Context(), uid,
+		)
 		if err != nil {
-			s.log.Error("list channels failed", "error", err)
+			s.internalError(
-			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+				w, r, "list channels failed", err,
+			)
+
 			return
 		}
-		s.respondJSON(w, r, &response{ID: uid, Nick: nick, Channels: channels}, http.StatusOK)
+
+		s.respondJSON(
+			w, r,
+			&response{
+				ID: uid, Nick: nick,
+				Channels: channels,
+			},
+			http.StatusOK,
+		)
 	}
 }
 
@@ -94,12 +196,18 @@ func (s *Handlers) HandleListAllChannels() http.HandlerFunc {
 		if !ok {
 			return
 		}
-		channels, err := s.params.Database.ListAllChannels(r.Context())
+
+		channels, err := s.params.Database.ListAllChannels(
+			r.Context(),
+		)
 		if err != nil {
-			s.log.Error("list all channels failed", "error", err)
+			s.internalError(
-			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+				w, r, "list all channels failed", err,
+			)
+
 			return
 		}
+
 		s.respondJSON(w, r, channels, http.StatusOK)
 	}
 }
@@ -111,278 +219,561 @@ 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(),
+
-			"SELECT id FROM channels WHERE name = ?", name).Scan(&chID)
+		err := s.params.Database.GetDB().QueryRowContext( //nolint:gosec // parameterized query
+			r.Context(),
+			"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)
+			s.respondError(
+				w, r, "channel not found",
+				http.StatusNotFound,
+			)
+
 			return
 		}
-		members, err := s.params.Database.ChannelMembers(r.Context(), chID)
+
+		members, err := s.params.Database.ChannelMembers(
+			r.Context(), chID,
+		)
 		if err != nil {
-			s.log.Error("channel members failed", "error", err)
+			s.internalError(
-			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+				w, r, "channel members failed", err,
+			)
+
 			return
 		}
+
 		s.respondJSON(w, r, members, http.StatusOK)
 	}
 }
 
-// HandleGetMessages returns all new messages (channel + DM) for the user via long-polling.
+// HandleGetMessages returns all new messages (channel + DM)
-// This is the single unified message stream — replaces separate channel/DM/poll endpoints.
+// for the user via long-polling.
 func (s *Handlers) HandleGetMessages() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		uid, _, ok := s.requireAuth(w, r)
 		if !ok {
 			return
 		}
-		afterID, _ := strconv.ParseInt(r.URL.Query().Get("after"), 10, 64)
+
-		limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
+		afterID, _ := strconv.ParseInt(
-		msgs, err := s.params.Database.PollMessages(r.Context(), uid, afterID, limit)
+			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.internalError(
-			s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+				w, r, "get messages failed", err,
+			)
+
 			return
 		}
+
 		s.respondJSON(w, r, msgs, http.StatusOK)
 	}
 }
 
-// HandleSendCommand handles all C2S commands via POST /messages.
+type sendRequest struct {
-// 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"`
+	Body    any      `json:"body,omitempty"`
 }
+
+// HandleSendCommand handles all C2S commands via POST
+// /messages.
+func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 	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 {
+		var req sendRequest
-			s.respondJSON(w, r, map[string]string{"error": "invalid request"}, http.StatusBadRequest)
+
+		err := json.NewDecoder(r.Body).Decode(&req)
+		if err != nil {
+			s.respondError(
+				w, r, "invalid request",
+				http.StatusBadRequest,
+			)
+
 			return
 		}
-		req.Command = strings.ToUpper(strings.TrimSpace(req.Command))
+
+		req.Command = strings.ToUpper(
+			strings.TrimSpace(req.Command),
+		)
 		req.To = strings.TrimSpace(req.To)
 
-		// Helper to extract body as string lines.
+		s.dispatchCommand(w, r, uid, nick, &req)
-		bodyLines := func() []string {
-			switch v := req.Body.(type) {
-			case []interface{}:
-				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
-			default:
-				return nil
 	}
 }
 
+func (s *Handlers) dispatchCommand(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	nick string,
+	req *sendRequest,
+) {
 	switch req.Command {
 	case "PRIVMSG", "NOTICE":
+		s.handlePrivmsg(w, r, uid, req)
+	case "JOIN":
+		s.handleJoin(w, r, uid, req)
+	case "PART":
+		s.handlePart(w, r, uid, req)
+	case "NICK":
+		s.handleNick(w, r, uid, req)
+	case "TOPIC":
+		s.handleTopic(w, r, uid, req)
+	case "PING":
+		s.respondJSON(
+			w, r,
+			map[string]string{
+				"command": "PONG",
+				"from":    s.params.Config.ServerName,
+			},
+			http.StatusOK,
+		)
+	default:
+		_ = nick
+
+		s.respondError(
+			w, r,
+			"unknown command: "+req.Command,
+			http.StatusBadRequest,
+		)
+	}
+}
+
+func (s *Handlers) handlePrivmsg(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	req *sendRequest,
+) {
 	if req.To == "" {
-				s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+		s.respondError(
+			w, r, "to field required",
+			http.StatusBadRequest,
+		)
+
 		return
 	}
-			lines := bodyLines()
+
+	lines := bodyLines(req.Body)
 	if len(lines) == 0 {
-				s.respondJSON(w, r, map[string]string{"error": "body required"}, http.StatusBadRequest)
+		s.respondError(
+			w, r, "body required", http.StatusBadRequest,
+		)
+
 		return
 	}
+
 	content := strings.Join(lines, "\n")
 
 	if strings.HasPrefix(req.To, "#") {
-				// Channel message
+		s.sendChannelMsg(w, r, uid, req.To, content)
-				var chID int64
-				err := s.params.Database.GetDB().QueryRowContext(r.Context(),
-					"SELECT id FROM channels WHERE name = ?", req.To).Scan(&chID)
-				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
+		s.sendDM(w, r, uid, req.To, content)
-				targetID, err := s.params.Database.GetUserByNick(r.Context(), req.To)
-				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":
+func (s *Handlers) sendChannelMsg(
-			if req.To == "" {
+	w http.ResponseWriter,
-				s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+	r *http.Request,
-				return
+	uid int64,
-			}
+	channel, content string,
-			channel := req.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 {
-				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
-			if !strings.HasPrefix(channel, "#") {
-				channel = "#" + channel
-			}
 	var chID int64
-			err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+
-				"SELECT id FROM channels WHERE name = ?", channel).Scan(&chID)
+	err := s.params.Database.GetDB().QueryRowContext( //nolint:gosec // parameterized query
+		r.Context(),
+		"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)
+		s.respondError(
-				return
+			w, r, "channel not found",
-			}
+			http.StatusNotFound,
-			if err := s.params.Database.PartChannel(r.Context(), chID, uid); 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":
-			lines := bodyLines()
-			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 {
-				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":
+	msgID, err := s.params.Database.SendMessage(
+		r.Context(), chID, uid, content,
+	)
+	if err != nil {
+		s.internalError(w, r, "send message failed", err)
+
+		return
+	}
+
+	s.respondJSON(
+		w, r,
+		map[string]any{"id": msgID, "status": "sent"},
+		http.StatusCreated,
+	)
+}
+
+func (s *Handlers) sendDM(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	toNick, content string,
+) {
+	targetID, err := s.params.Database.GetUserByNick(
+		r.Context(), toNick,
+	)
+	if err != nil {
+		s.respondError(
+			w, r, "user not found", http.StatusNotFound,
+		)
+
+		return
+	}
+
+	msgID, err := s.params.Database.SendDM(
+		r.Context(), uid, targetID, content,
+	)
+	if err != nil {
+		s.internalError(w, r, "send dm failed", err)
+
+		return
+	}
+
+	s.respondJSON(
+		w, r,
+		map[string]any{"id": msgID, "status": "sent"},
+		http.StatusCreated,
+	)
+}
+
+func (s *Handlers) handleJoin(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	req *sendRequest,
+) {
 	if req.To == "" {
-				s.respondJSON(w, r, map[string]string{"error": "to field required"}, http.StatusBadRequest)
+		s.respondError(
+			w, r, "to field required",
+			http.StatusBadRequest,
+		)
+
 		return
 	}
-			lines := bodyLines()
+
-			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
 	if !strings.HasPrefix(channel, "#") {
 		channel = "#" + channel
 	}
-			if err := s.params.Database.SetTopic(r.Context(), channel, uid, topic); err != nil {
+
-				s.log.Error("set topic failed", "error", err)
+	chID, err := s.params.Database.GetOrCreateChannel(
-				s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+		r.Context(), channel,
+	)
+	if err != nil {
+		s.internalError(
+			w, r, "get/create channel failed", err,
+		)
+
 		return
 	}
-			s.respondJSON(w, r, map[string]string{"status": "ok", "topic": topic}, http.StatusOK)
 
-		case "PING":
+	err = s.params.Database.JoinChannel(
-			s.respondJSON(w, r, map[string]string{"command": "PONG", "from": s.params.Config.ServerName}, http.StatusOK)
+		r.Context(), chID, uid,
+	)
+	if err != nil {
+		s.internalError(w, r, "join channel failed", err)
 
-		default:
+		return
-			_ = 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).
+	s.respondJSON(
+		w, r,
+		map[string]string{
+			"status": "joined", "channel": channel,
+		},
+		http.StatusOK,
+	)
+}
+
+func (s *Handlers) handlePart(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	req *sendRequest,
+) {
+	if req.To == "" {
+		s.respondError(
+			w, r, "to field required",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	channel := req.To
+	if !strings.HasPrefix(channel, "#") {
+		channel = "#" + channel
+	}
+
+	var chID int64
+
+	err := s.params.Database.GetDB().QueryRowContext( //nolint:gosec // parameterized query
+		r.Context(),
+		"SELECT id FROM channels WHERE name = ?",
+		channel,
+	).Scan(&chID)
+	if err != nil {
+		s.respondError(
+			w, r, "channel not found",
+			http.StatusNotFound,
+		)
+
+		return
+	}
+
+	err = s.params.Database.PartChannel(
+		r.Context(), chID, uid,
+	)
+	if err != nil {
+		s.internalError(w, r, "part channel failed", err)
+
+		return
+	}
+
+	s.respondJSON(
+		w, r,
+		map[string]string{
+			"status": "parted", "channel": channel,
+		},
+		http.StatusOK,
+	)
+}
+
+func (s *Handlers) handleNick(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	req *sendRequest,
+) {
+	lines := bodyLines(req.Body)
+	if len(lines) == 0 {
+		s.respondError(
+			w, r, "body required (new nick)",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	newNick := strings.TrimSpace(lines[0])
+	if newNick == "" || len(newNick) > maxNickLen {
+		s.respondError(
+			w, r, "nick must be 1-32 characters",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	err := s.params.Database.ChangeNick(
+		r.Context(), uid, newNick,
+	)
+	if err != nil {
+		if strings.Contains(err.Error(), "UNIQUE") {
+			s.respondError(
+				w, r, "nick already in use",
+				http.StatusConflict,
+			)
+
+			return
+		}
+
+		s.internalError(w, r, "change nick failed", err)
+
+		return
+	}
+
+	s.respondJSON(
+		w, r,
+		map[string]string{"status": "ok", "nick": newNick},
+		http.StatusOK,
+	)
+}
+
+func (s *Handlers) handleTopic(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	req *sendRequest,
+) {
+	if req.To == "" {
+		s.respondError(
+			w, r, "to field required",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	lines := bodyLines(req.Body)
+	if len(lines) == 0 {
+		s.respondError(
+			w, r, "body required (topic text)",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	topic := strings.Join(lines, " ")
+
+	channel := req.To
+	if !strings.HasPrefix(channel, "#") {
+		channel = "#" + channel
+	}
+
+	err := s.params.Database.SetTopic(
+		r.Context(), channel, uid, topic,
+	)
+	if err != nil {
+		s.internalError(w, r, "set topic failed", err)
+
+		return
+	}
+
+	s.respondJSON(
+		w, r,
+		map[string]string{"status": "ok", "topic": topic},
+		http.StatusOK,
+	)
+}
+
+// HandleGetHistory returns message history for a specific
+// target (channel or DM).
 func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		uid, _, ok := s.requireAuth(w, r)
 		if !ok {
 			return
 		}
+
 		target := r.URL.Query().Get("target")
 		if target == "" {
-			s.respondJSON(w, r, map[string]string{"error": "target required"}, http.StatusBadRequest)
+			s.respondError(
+				w, r, "target required",
+				http.StatusBadRequest,
+			)
+
 			return
 		}
-		beforeID, _ := strconv.ParseInt(r.URL.Query().Get("before"), 10, 64)
+
-		limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
+		beforeID, _ := strconv.ParseInt(
+			r.URL.Query().Get("before"), 10, 64,
+		)
+
+		limit, _ := strconv.Atoi(
+			r.URL.Query().Get("limit"),
+		)
 		if limit <= 0 {
-			limit = 50
+			limit = defaultHistory
 		}
 
 		if strings.HasPrefix(target, "#") {
-			// Channel history
+			s.getChannelHistory(
-			var chID int64
+				w, r, target, beforeID, limit,
-			err := s.params.Database.GetDB().QueryRowContext(r.Context(),
+			)
-				"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
-			}
-			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
+			s.getDMHistory(
-			targetID, err := s.params.Database.GetUserByNick(r.Context(), target)
+				w, r, uid, target, beforeID, limit,
+			)
+		}
+	}
+}
+
+func (s *Handlers) getChannelHistory(
+	w http.ResponseWriter,
+	r *http.Request,
+	target string,
+	beforeID int64,
+	limit int,
+) {
+	var chID int64
+
+	err := s.params.Database.GetDB().QueryRowContext( //nolint:gosec // parameterized query
+		r.Context(),
+		"SELECT id FROM channels WHERE name = ?",
+		target,
+	).Scan(&chID)
 	if err != nil {
-				s.respondJSON(w, r, map[string]string{"error": "user not found"}, http.StatusNotFound)
+		s.respondError(
+			w, r, "channel not found",
+			http.StatusNotFound,
+		)
+
 		return
 	}
-			msgs, err := s.params.Database.GetDMsBefore(r.Context(), uid, targetID, beforeID, limit)
+
+	msgs, err := s.params.Database.GetMessagesBefore(
+		r.Context(), chID, beforeID, limit,
+	)
 	if err != nil {
-				s.log.Error("get dm history failed", "error", err)
+		s.internalError(w, r, "get history failed", err)
-				s.respondJSON(w, r, map[string]string{"error": "internal error"}, http.StatusInternalServerError)
+
 		return
 	}
+
 	s.respondJSON(w, r, msgs, http.StatusOK)
 }
+
+func (s *Handlers) getDMHistory(
+	w http.ResponseWriter,
+	r *http.Request,
+	uid int64,
+	target string,
+	beforeID int64,
+	limit int,
+) {
+	targetID, err := s.params.Database.GetUserByNick(
+		r.Context(), target,
+	)
+	if err != nil {
+		s.respondError(
+			w, r, "user not found", http.StatusNotFound,
+		)
+
+		return
 	}
+
+	msgs, err := s.params.Database.GetDMsBefore(
+		r.Context(), uid, targetID, beforeID, limit,
+	)
+	if err != nil {
+		s.internalError(
+			w, r, "get dm history failed", err,
+		)
+
+		return
+	}
+
+	s.respondJSON(w, r, msgs, http.StatusOK)
 }
 
 // HandleServerInfo returns server metadata (MOTD, name).
@@ -391,6 +782,7 @@ 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

@@ -2,7 +2,6 @@ package models
 
 import (
 	"context"
-	"fmt"
 	"time"
 )
 
@@ -23,5 +22,5 @@ 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, ErrUserLookupNotAvailable
 }

internal/models/channel_member.go

@@ -2,7 +2,6 @@ package models
 
 import (
 	"context"
-	"fmt"
 	"time"
 )
 
@@ -23,7 +22,7 @@ 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, ErrUserLookupNotAvailable
 }
 
 // Channel returns the full Channel for this membership.
@@ -32,5 +31,5 @@ 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, ErrChannelLookupNotAvailable
 }

internal/models/model.go

@@ -6,6 +6,7 @@ package models
 import (
 	"context"
 	"database/sql"
+	"errors"
 )
 
 // DB is the interface that models use to query the database.
@@ -24,6 +25,12 @@ type ChannelLookup interface {
 	GetChannelByID(ctx context.Context, id string) (*Channel, error)
 }
 
+// Sentinel errors for model lookup methods.
+var (
+	ErrUserLookupNotAvailable    = errors.New("user lookup not available")
+	ErrChannelLookupNotAvailable = errors.New("channel lookup not available")
+)
+
 // Base is embedded in all model structs to provide database access.
 type Base struct {
 	db DB
@@ -40,7 +47,7 @@ func (b *Base) GetDB() *sql.DB {
 }
 
 // GetUserLookup returns the DB as a UserLookup if it implements the interface.
-func (b *Base) GetUserLookup() UserLookup {
+func (b *Base) GetUserLookup() UserLookup { //nolint:ireturn // interface return is intentional
 	if ul, ok := b.db.(UserLookup); ok {
 		return ul
 	}
@@ -49,7 +56,7 @@ func (b *Base) GetUserLookup() UserLookup {
 }
 
 // GetChannelLookup returns the DB as a ChannelLookup if it implements the interface.
-func (b *Base) GetChannelLookup() ChannelLookup {
+func (b *Base) GetChannelLookup() ChannelLookup { //nolint:ireturn // interface return is intentional
 	if cl, ok := b.db.(ChannelLookup); ok {
 		return cl
 	}

internal/models/session.go

@@ -2,7 +2,6 @@ package models
 
 import (
 	"context"
-	"fmt"
 	"time"
 )
 
@@ -23,5 +22,5 @@ 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, ErrUserLookupNotAvailable
 }

internal/server/routes.go

@@ -71,17 +71,37 @@ 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
+			s.serveSPA(distFS, fileServer, w, r)
-			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)
 		})
 	}
 }
+
+func (s *Server) serveSPA(
+	distFS fs.FS,
+	fileServer http.Handler,
+	w http.ResponseWriter,
+	r *http.Request,
+) {
+	readFS, ok := distFS.(fs.ReadFileFS)
+	if !ok {
+		http.Error(w, "filesystem error", http.StatusInternalServerError)
+
+		return
+	}
+
+	// Try to serve the file; fall back to index.html for SPA routing.
+	f, err := readFS.ReadFile(r.URL.Path[1:])
+	if err != 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)
+}