refactor: replace Bearer token auth with HttpOnly cookies

- Remove POST /api/v1/register endpoint entirely
- Session creation (POST /api/v1/session) now sets neoirc_auth HttpOnly
  cookie instead of returning token in JSON body
- Login (POST /api/v1/login) now sets neoirc_auth HttpOnly cookie
  instead of returning token in JSON body
- Add PASS IRC command for setting session password (enables multi-client
  login via POST /api/v1/login)
- All per-request auth reads from neoirc_auth cookie instead of
  Authorization: Bearer header
- Cookie properties: HttpOnly, SameSite=Strict, Secure when behind TLS
- Logout and QUIT clear the auth cookie
- Update CORS to AllowCredentials:true with origin reflection
- Remove Authorization from CORS AllowedHeaders
- Update CLI client to use cookie jar (net/http/cookiejar)
- Remove Token field from SessionResponse
- Add SetPassword to DB layer, remove RegisterUser
- Comprehensive test updates for cookie-based auth
- Add tests: TestPassCommand, TestPassCommandShortPassword,
  TestPassCommandEmpty, TestSessionCookie
- Update README extensively: auth model, API reference, curl examples,
  security model, design principles, roadmap

closes #83

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all build lint fmt fmt-check test check clean run debug docker hooks
+.PHONY: all build lint fmt fmt-check test check clean run debug docker hooks ensure-web-dist
 
 BINARY := neoircd
 VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
@@ -7,10 +7,21 @@ LDFLAGS := -X main.Version=$(VERSION) -X main.Buildarch=$(BUILDARCH)
 
 all: check build
 
-build:
+# ensure-web-dist creates placeholder files so //go:embed dist/* in
+# web/embed.go resolves without a full Node.js build.  The real SPA is
+# built by the web-builder Docker stage; these placeholders let
+# "make test" and "make build" work outside Docker.
+ensure-web-dist:
+	@if [ ! -d web/dist ]; then \
+		mkdir -p web/dist && \
+		touch web/dist/index.html web/dist/style.css web/dist/app.js && \
+		echo "==> Created placeholder web/dist/ for go:embed"; \
+	fi
+
+build: ensure-web-dist
 	go build -ldflags "$(LDFLAGS)" -o bin/$(BINARY) ./cmd/neoircd
 
-lint:
+lint: ensure-web-dist
 	golangci-lint run --config .golangci.yml ./...
 
 fmt:
@@ -20,7 +31,7 @@ fmt:
 fmt-check:
 	@test -z "$$(gofmt -l .)" || (echo "Files not formatted:" && gofmt -l . && exit 1)
 
-test:
+test: ensure-web-dist
 	go test -timeout 30s -v -race -cover ./...
 
 # check runs all validation without making changes

cmd/neoirc-cli/main.go

@@ -1,911 +1,8 @@
 // Package main is the entry point for the neoirc-cli client.
 package main
 
-import (
+import "git.eeqj.de/sneak/neoirc/internal/cli"
-	"fmt"
-	"os"
-	"strings"
-	"sync"
-	"time"
-
-	api "git.eeqj.de/sneak/neoirc/cmd/neoirc-cli/api"
-	"git.eeqj.de/sneak/neoirc/internal/irc"
-)
-
-const (
-	splitParts  = 2
-	pollTimeout = 15
-	pollRetry   = 2 * time.Second
-	timeFormat  = "15:04"
-)
-
-// App holds the application state.
-type App struct {
-	ui     *UI
-	client *api.Client
-
-	mu        sync.Mutex
-	nick      string
-	target    string
-	connected bool
-	lastQID   int64
-	stopPoll  chan struct{}
-}
 
 func main() {
-	app := &App{ //nolint:exhaustruct
+	cli.Run()
-		ui:   NewUI(),
-		nick: "guest",
-	}
-
-	app.ui.OnInput(app.handleInput)
-	app.ui.SetStatus(app.nick, "", "disconnected")
-
-	app.ui.AddStatus(
-		"Welcome to neoirc-cli — 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)
-		os.Exit(1)
-	}
-}
-
-func (a *App) handleInput(text string) {
-	if strings.HasPrefix(text, "/") {
-		a.handleCommand(text)
-
-		return
-	}
-
-	a.mu.Lock()
-	target := a.target
-	connected := a.connected
-	a.mu.Unlock()
-
-	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{ //nolint:exhaustruct
-		Command: irc.CmdPrivmsg,
-		To:      target,
-		Body:    []string{text},
-	})
-	if err != nil {
-		a.ui.AddStatus(
-			"[red]Send error: " + err.Error(),
-		)
-
-		return
-	}
-
-	timestamp := time.Now().Format(timeFormat)
-
-	a.mu.Lock()
-	nick := a.nick
-	a.mu.Unlock()
-
-	a.ui.AddLine(target, fmt.Sprintf(
-		"[gray]%s [green]<%s>[white] %s",
-		timestamp, nick, text,
-	))
-}
-
-func (a *App) handleCommand(text string) {
-	parts := strings.SplitN(text, " ", splitParts)
-	cmd := strings.ToLower(parts[0])
-
-	args := ""
-	if len(parts) > 1 {
-		args = parts[1]
-	}
-
-	a.dispatchCommand(cmd, args)
-}
-
-func (a *App) dispatchCommand(cmd, args string) {
-	switch cmd {
-	case "/connect":
-		a.cmdConnect(args)
-	case "/nick":
-		a.cmdNick(args)
-	case "/join":
-		a.cmdJoin(args)
-	case "/part":
-		a.cmdPart(args)
-	case "/msg":
-		a.cmdMsg(args)
-	case "/query":
-		a.cmdQuery(args)
-	case "/topic":
-		a.cmdTopic(args)
-	case "/window", "/w":
-		a.cmdWindow(args)
-	case "/quit":
-		a.cmdQuit()
-	case "/help":
-		a.cmdHelp()
-	default:
-		a.dispatchInfoCommand(cmd, args)
-	}
-}
-
-func (a *App) dispatchInfoCommand(cmd, args string) {
-	switch cmd {
-	case "/names":
-		a.cmdNames()
-	case "/list":
-		a.cmdList()
-	case "/motd":
-		a.cmdMotd()
-	case "/who":
-		a.cmdWho(args)
-	case "/whois":
-		a.cmdWhois(args)
-	default:
-		a.ui.AddStatus(
-			"[red]Unknown command: " + cmd,
-		)
-	}
-}
-
-func (a *App) cmdConnect(serverURL string) {
-	if serverURL == "" {
-		a.ui.AddStatus(
-			"[red]Usage: /connect <server-url>",
-		)
-
-		return
-	}
-
-	serverURL = strings.TrimRight(serverURL, "/")
-
-	a.ui.AddStatus("Connecting to " + 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,
-		))
-
-		return
-	}
-
-	a.mu.Lock()
-	a.client = client
-	a.nick = resp.Nick
-	a.connected = true
-	a.lastQID = 0
-	a.mu.Unlock()
-
-	a.ui.AddStatus(fmt.Sprintf(
-		"[green]Connected! Nick: %s, Session: %d",
-		resp.Nick, resp.ID,
-	))
-	a.ui.SetStatus(resp.Nick, "", "connected")
-
-	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()
-
-	if !connected {
-		a.mu.Lock()
-		a.nick = nick
-		a.mu.Unlock()
-
-		a.ui.AddStatus(
-			"Nick set to " + nick +
-				" (will be used on connect)",
-		)
-
-		return
-	}
-
-	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-		Command: irc.CmdNick,
-		Body:    []string{nick},
-	})
-	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[red]Nick change failed: %v", err,
-		))
-
-		return
-	}
-
-	a.mu.Lock()
-	a.nick = nick
-	target := a.target
-	a.mu.Unlock()
-
-	a.ui.SetStatus(nick, target, "connected")
-	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
-	}
-
-	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
-	}
-
-	a.mu.Lock()
-	a.target = channel
-	nick := a.nick
-	a.mu.Unlock()
-
-	a.ui.SwitchToBuffer(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,
-		"[yellow]*** Left "+channel,
-	)
-
-	a.mu.Lock()
-	if a.target == channel {
-		a.target = ""
-	}
-
-	nick := a.nick
-	a.mu.Unlock()
-
-	a.ui.SwitchBuffer(0)
-	a.ui.SetStatus(nick, "", "connected")
-}
-
-func (a *App) cmdMsg(args string) {
-	parts := strings.SplitN(args, " ", splitParts)
-	if len(parts) < splitParts {
-		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{ //nolint:exhaustruct
-		Command: irc.CmdPrivmsg,
-		To:      target,
-		Body:    []string{text},
-	})
-	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[red]Send failed: %v", err,
-		))
-
-		return
-	}
-
-	timestamp := time.Now().Format(timeFormat)
-
-	a.ui.AddLine(target, fmt.Sprintf(
-		"[gray]%s [green]<%s>[white] %s",
-		timestamp, nick, text,
-	))
-}
-
-func (a *App) cmdQuery(nick string) {
-	if nick == "" {
-		a.ui.AddStatus(
-			"[red]Usage: /query <nick>",
-		)
-
-		return
-	}
-
-	a.mu.Lock()
-	a.target = nick
-	myNick := a.nick
-	a.mu.Unlock()
-
-	a.ui.SwitchToBuffer(nick)
-	a.ui.SetStatus(myNick, nick, "connected")
-}
-
-func (a *App) cmdTopic(args string) {
-	a.mu.Lock()
-	target := a.target
-	connected := a.connected
-	a.mu.Unlock()
-
-	if !connected {
-		a.ui.AddStatus("[red]Not connected")
-
-		return
-	}
-
-	if !strings.HasPrefix(target, "#") {
-		a.ui.AddStatus("[red]Not in a channel")
-
-		return
-	}
-
-	if args == "" {
-		err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-			Command: irc.CmdTopic,
-			To:      target,
-		})
-		if err != nil {
-			a.ui.AddStatus(fmt.Sprintf(
-				"[red]Topic query failed: %v", err,
-			))
-		}
-
-		return
-	}
-
-	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
-		Command: irc.CmdTopic,
-		To:      target,
-		Body:    []string{args},
-	})
-	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[red]Topic set failed: %v", err,
-		))
-	}
-}
-
-func (a *App) cmdNames() {
-	a.mu.Lock()
-	target := a.target
-	connected := a.connected
-	a.mu.Unlock()
-
-	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
-	}
-
-	a.ui.AddLine(target, fmt.Sprintf(
-		"[cyan]*** Members of %s: %s",
-		target, strings.Join(members, " "),
-	))
-}
-
-func (a *App) cmdList() {
-	a.mu.Lock()
-	connected := a.connected
-	a.mu.Unlock()
-
-	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) cmdMotd() {
-	a.mu.Lock()
-	connected := a.connected
-	a.mu.Unlock()
-
-	if !connected {
-		a.ui.AddStatus("[red]Not connected")
-
-		return
-	}
-
-	err := a.client.SendMessage(
-		&api.Message{Command: irc.CmdMotd}, //nolint:exhaustruct
-	)
-	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[red]MOTD failed: %v", err,
-		))
-	}
-}
-
-func (a *App) cmdWho(args string) {
-	a.mu.Lock()
-	connected := a.connected
-	target := a.target
-	a.mu.Unlock()
-
-	if !connected {
-		a.ui.AddStatus("[red]Not connected")
-
-		return
-	}
-
-	channel := args
-	if channel == "" {
-		channel = target
-	}
-
-	if channel == "" ||
-		!strings.HasPrefix(channel, "#") {
-		a.ui.AddStatus(
-			"[red]Usage: /who #channel",
-		)
-
-		return
-	}
-
-	err := a.client.SendMessage(
-		&api.Message{ //nolint:exhaustruct
-			Command: irc.CmdWho, To: channel,
-		},
-	)
-	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[red]WHO failed: %v", err,
-		))
-	}
-}
-
-func (a *App) cmdWhois(args string) {
-	a.mu.Lock()
-	connected := a.connected
-	a.mu.Unlock()
-
-	if !connected {
-		a.ui.AddStatus("[red]Not connected")
-
-		return
-	}
-
-	if args == "" {
-		a.ui.AddStatus(
-			"[red]Usage: /whois <nick>",
-		)
-
-		return
-	}
-
-	err := a.client.SendMessage(
-		&api.Message{ //nolint:exhaustruct
-			Command: irc.CmdWhois, To: args,
-		},
-	)
-	if err != nil {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[red]WHOIS failed: %v", err,
-		))
-	}
-}
-
-func (a *App) cmdWindow(args string) {
-	if args == "" {
-		a.ui.AddStatus(
-			"[red]Usage: /window <number>",
-		)
-
-		return
-	}
-
-	var bufIndex int
-
-	_, _ = fmt.Sscanf(args, "%d", &bufIndex)
-
-	a.ui.SwitchBuffer(bufIndex)
-
-	a.mu.Lock()
-	nick := a.nick
-	a.mu.Unlock()
-
-	if bufIndex >= 0 && bufIndex < a.ui.BufferCount() {
-		buf := a.ui.buffers[bufIndex]
-		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")
-		}
-	}
-}
-
-func (a *App) cmdQuit() {
-	a.mu.Lock()
-
-	if a.connected && a.client != nil {
-		_ = a.client.SendMessage(
-			&api.Message{Command: irc.CmdQuit}, //nolint:exhaustruct
-		)
-	}
-
-	if a.stopPoll != nil {
-		close(a.stopPoll)
-	}
-
-	a.mu.Unlock()
-	a.ui.Stop()
-}
-
-func (a *App) cmdHelp() {
-	help := []string{
-		"[cyan]*** neoirc-cli commands:",
-		"  /connect <url>  — Connect to server",
-		"  /nick <name>    — Change nickname",
-		"  /join #channel  — Join channel",
-		"  /part [#chan]    — Leave channel",
-		"  /msg <nick> <text> — Send DM",
-		"  /query <nick>   — Open DM window",
-		"  /topic [text]   — View/set topic",
-		"  /names          — List channel members",
-		"  /list           — List channels",
-		"  /who [#channel] — List users in channel",
-		"  /whois <nick>   — Show user info",
-		"  /motd           — Show message of the day",
-		"  /window <n>     — Switch buffer",
-		"  /quit           — Disconnect and exit",
-		"  /help           — This help",
-		"  Plain text sends to current target.",
-	}
-
-	for _, line := range help {
-		a.ui.AddStatus(line)
-	}
-}
-
-// pollLoop long-polls for messages in the background.
-func (a *App) pollLoop() {
-	for {
-		select {
-		case <-a.stopPoll:
-			return
-		default:
-		}
-
-		a.mu.Lock()
-		client := a.client
-		lastQID := a.lastQID
-		a.mu.Unlock()
-
-		if client == nil {
-			return
-		}
-
-		result, err := client.PollMessages(
-			lastQID, pollTimeout,
-		)
-		if err != nil {
-			time.Sleep(pollRetry)
-
-			continue
-		}
-
-		if result.LastID > 0 {
-			a.mu.Lock()
-			a.lastQID = result.LastID
-			a.mu.Unlock()
-		}
-
-		for i := range result.Messages {
-			a.handleServerMessage(&result.Messages[i])
-		}
-	}
-}
-
-func (a *App) handleServerMessage(msg *api.Message) {
-	timestamp := a.formatTS(msg)
-
-	a.mu.Lock()
-	myNick := a.nick
-	a.mu.Unlock()
-
-	switch msg.Command {
-	case irc.CmdPrivmsg:
-		a.handlePrivmsgEvent(msg, timestamp, myNick)
-	case irc.CmdJoin:
-		a.handleJoinEvent(msg, timestamp)
-	case irc.CmdPart:
-		a.handlePartEvent(msg, timestamp)
-	case irc.CmdQuit:
-		a.handleQuitEvent(msg, timestamp)
-	case irc.CmdNick:
-		a.handleNickEvent(msg, timestamp, myNick)
-	case irc.CmdNotice:
-		a.handleNoticeEvent(msg, timestamp)
-	case irc.CmdTopic:
-		a.handleTopicEvent(msg, timestamp)
-	default:
-		a.handleDefaultEvent(msg, timestamp)
-	}
-}
-
-func (a *App) formatTS(msg *api.Message) string {
-	if msg.TS != "" {
-		return msg.ParseTS().UTC().Format(timeFormat)
-	}
-
-	return time.Now().Format(timeFormat)
-}
-
-func (a *App) handlePrivmsgEvent(
-	msg *api.Message, timestamp, myNick string,
-) {
-	lines := msg.BodyLines()
-	text := strings.Join(lines, " ")
-
-	if msg.From == myNick {
-		return
-	}
-
-	target := msg.To
-	if !strings.HasPrefix(target, "#") {
-		target = msg.From
-	}
-
-	a.ui.AddLine(target, fmt.Sprintf(
-		"[gray]%s [green]<%s>[white] %s",
-		timestamp, msg.From, text,
-	))
-}
-
-func (a *App) handleJoinEvent(
-	msg *api.Message, timestamp string,
-) {
-	if msg.To == "" {
-		return
-	}
-
-	a.ui.AddLine(msg.To, fmt.Sprintf(
-		"[gray]%s [yellow]*** %s has joined %s",
-		timestamp, msg.From, msg.To,
-	))
-}
-
-func (a *App) handlePartEvent(
-	msg *api.Message, timestamp string,
-) {
-	if msg.To == "" {
-		return
-	}
-
-	lines := msg.BodyLines()
-	reason := strings.Join(lines, " ")
-
-	if reason != "" {
-		a.ui.AddLine(msg.To, fmt.Sprintf(
-			"[gray]%s [yellow]*** %s has left %s (%s)",
-			timestamp, msg.From, msg.To, reason,
-		))
-	} else {
-		a.ui.AddLine(msg.To, fmt.Sprintf(
-			"[gray]%s [yellow]*** %s has left %s",
-			timestamp, msg.From, msg.To,
-		))
-	}
-}
-
-func (a *App) handleQuitEvent(
-	msg *api.Message, timestamp string,
-) {
-	lines := msg.BodyLines()
-	reason := strings.Join(lines, " ")
-
-	if reason != "" {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[gray]%s [yellow]*** %s has quit (%s)",
-			timestamp, msg.From, reason,
-		))
-	} else {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[gray]%s [yellow]*** %s has quit",
-			timestamp, msg.From,
-		))
-	}
-}
-
-func (a *App) handleNickEvent(
-	msg *api.Message, timestamp, 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",
-		timestamp, msg.From, newNick,
-	))
-}
-
-func (a *App) handleNoticeEvent(
-	msg *api.Message, timestamp string,
-) {
-	lines := msg.BodyLines()
-	text := strings.Join(lines, " ")
-
-	a.ui.AddStatus(fmt.Sprintf(
-		"[gray]%s [magenta]--%s-- %s",
-		timestamp, msg.From, text,
-	))
-}
-
-func (a *App) handleTopicEvent(
-	msg *api.Message, timestamp 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",
-		timestamp, msg.From, text,
-	))
-}
-
-func (a *App) handleDefaultEvent(
-	msg *api.Message, timestamp string,
-) {
-	lines := msg.BodyLines()
-	text := strings.Join(lines, " ")
-
-	if text != "" {
-		a.ui.AddStatus(fmt.Sprintf(
-			"[gray]%s [white][%s] %s",
-			timestamp, msg.Command, text,
-		))
-	}
 }

cmd/neoircd/main.go

@@ -10,6 +10,7 @@ import (
 	"git.eeqj.de/sneak/neoirc/internal/logger"
 	"git.eeqj.de/sneak/neoirc/internal/middleware"
 	"git.eeqj.de/sneak/neoirc/internal/server"
+	"git.eeqj.de/sneak/neoirc/internal/stats"
 	"go.uber.org/fx"
 )
 
@@ -35,6 +36,7 @@ func main() {
 			server.New,
 			middleware.New,
 			healthcheck.New,
+			stats.New,
 		),
 		fx.Invoke(func(*server.Server) {}),
 	).Run()

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/99designs/basicauth-go v0.0.0-20230316000542-bf6f9cbbf0f8
 	github.com/gdamore/tcell/v2 v2.13.8
 	github.com/getsentry/sentry-go v0.42.0
-	github.com/go-chi/chi v1.5.5
+	github.com/go-chi/chi/v5 v5.2.1
 	github.com/go-chi/cors v1.2.2
 	github.com/google/uuid v1.6.0
 	github.com/joho/godotenv v1.5.1

go.sum

@@ -18,8 +18,8 @@ github.com/gdamore/tcell/v2 v2.13.8 h1:Mys/Kl5wfC/GcC5Cx4C2BIQH9dbnhnkPgS9/wF3Rl
 github.com/gdamore/tcell/v2 v2.13.8/go.mod h1:+Wfe208WDdB7INEtCsNrAN6O2m+wsTPk1RAovjaILlo=
 github.com/getsentry/sentry-go v0.42.0 h1:eeFMACuZTbUQf90RE8dE4tXeSe4CZyfvR1MBL7RLEt8=
 github.com/getsentry/sentry-go v0.42.0/go.mod h1:eRXCoh3uvmjQLY6qu63BjUZnaBu5L5WhMV1RwYO8W5s=
-github.com/go-chi/chi v1.5.5 h1:vOB/HbEMt9QqBqErz07QehcOKHaWFtuj87tTDVz2qXE=
+github.com/go-chi/chi/v5 v5.2.1 h1:KOIHODQj58PmL80G2Eak4WdvUzjSJSm0vG72crDCqb8=
-github.com/go-chi/chi v1.5.5/go.mod h1:C9JqLr3tIYjDOZpzn+BCuxY8z8vmca43EeMgyZt7irw=
+github.com/go-chi/chi/v5 v5.2.1/go.mod h1:L2yAIGWB3H+phAw1NxKwWM+7eUH/lU8pOMm5hHcoops=
 github.com/go-chi/cors v1.2.2 h1:Jmey33TE+b+rB7fT8MUy1u0I4L+NARQlK6LhzKPSyQE=
 github.com/go-chi/cors v1.2.2/go.mod h1:sSbTewc+6wYHBBCW7ytsFSn836hqM7JxpglAy2Vzc58=
 github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=

internal/cli/api/client.go

@@ -9,12 +9,13 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/http/cookiejar"
 	"net/url"
 	"strconv"
 	"strings"
 	"time"
 
-	"git.eeqj.de/sneak/neoirc/internal/irc"
+	"git.eeqj.de/sneak/neoirc/pkg/irc"
 )
 
 const (
@@ -28,28 +29,48 @@ var errHTTP = errors.New("HTTP error")
 // Client wraps HTTP calls to the neoirc server API.
 type Client struct {
 	BaseURL    string
-	Token      string
 	HTTPClient *http.Client
 }
 
-// NewClient creates a new API client.
+// NewClient creates a new API client with a cookie jar
+// for automatic auth cookie management.
 func NewClient(baseURL string) *Client {
-	return &Client{ //nolint:exhaustruct // Token set after CreateSession
+	jar, _ := cookiejar.New(nil)
+
+	return &Client{
 		BaseURL: baseURL,
 		HTTPClient: &http.Client{ //nolint:exhaustruct // defaults fine
 			Timeout: httpTimeout,
+			Jar:     jar,
 		},
 	}
 }
 
 // CreateSession creates a new session on the server.
+// If the server requires hashcash proof-of-work, it
+// automatically fetches the difficulty and computes a
+// valid stamp.
 func (client *Client) CreateSession(
 	nick string,
 ) (*SessionResponse, error) {
+	// Fetch server info to check for hashcash requirement.
+	info, err := client.GetServerInfo()
+
+	var hashcashStamp string
+
+	if err == nil && info.HashcashBits > 0 {
+		resource := info.Name
+		if resource == "" {
+			resource = "neoirc"
+		}
+
+		hashcashStamp = MintHashcash(info.HashcashBits, resource)
+	}
+
 	data, err := client.do(
 		http.MethodPost,
 		"/api/v1/session",
-		&SessionRequest{Nick: nick},
+		&SessionRequest{Nick: nick, Hashcash: hashcashStamp},
 	)
 	if err != nil {
 		return nil, err
@@ -62,8 +83,6 @@ func (client *Client) CreateSession(
 		return nil, fmt.Errorf("decode session: %w", err)
 	}
 
-	client.Token = resp.Token
-
 	return &resp, nil
 }
 
@@ -104,6 +123,7 @@ func (client *Client) PollMessages(
 		Timeout: time.Duration(
 			timeout+pollExtraTime,
 		) * time.Second,
+		Jar: client.HTTPClient.Jar,
 	}
 
 	params := url.Values{}
@@ -128,10 +148,6 @@ func (client *Client) PollMessages(
 		return nil, fmt.Errorf("new request: %w", err)
 	}
 
-	request.Header.Set(
-		"Authorization", "Bearer "+client.Token,
-	)
-
 	resp, err := pollClient.Do(request)
 	if err != nil {
 		return nil, fmt.Errorf("poll request: %w", err)
@@ -287,12 +303,6 @@ func (client *Client) do(
 		"Content-Type", "application/json",
 	)
 
-	if client.Token != "" {
-		request.Header.Set(
-			"Authorization", "Bearer "+client.Token,
-		)
-	}
-
 	resp, err := client.HTTPClient.Do(request)
 	if err != nil {
 		return nil, fmt.Errorf("http: %w", err)

internal/cli/api/hashcash.go

@@ -0,0 +1,98 @@
+package neoircapi
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"time"
+
+	"git.eeqj.de/sneak/neoirc/internal/hashcash"
+)
+
+const (
+	// bitsPerByte is the number of bits in a byte.
+	bitsPerByte = 8
+	// fullByteMask is 0xFF, a mask for all bits in a byte.
+	fullByteMask = 0xFF
+	// counterSpace is the range for random counter seeds.
+	counterSpace = 1 << 48
+)
+
+// MintHashcash computes a hashcash stamp with the given
+// difficulty (leading zero bits) and resource string.
+func MintHashcash(bits int, resource string) string {
+	date := time.Now().UTC().Format("060102")
+	prefix := fmt.Sprintf(
+		"1:%d:%s:%s::", bits, date, resource,
+	)
+
+	for {
+		counter := randomCounter()
+		stamp := prefix + counter
+		hash := sha256.Sum256([]byte(stamp))
+
+		if hasLeadingZeroBits(hash[:], bits) {
+			return stamp
+		}
+	}
+}
+
+// MintChannelHashcash computes a hashcash stamp bound to
+// a specific channel and message body. The stamp format
+// is 1:bits:YYMMDD:channel:bodyhash:counter where
+// bodyhash is the hex-encoded SHA-256 of the message
+// body bytes. Delegates to the internal/hashcash package.
+func MintChannelHashcash(
+	bits int,
+	channel string,
+	body []byte,
+) string {
+	bodyHash := hashcash.BodyHash(body)
+
+	return hashcash.MintChannelStamp(
+		bits, channel, bodyHash,
+	)
+}
+
+// hasLeadingZeroBits checks if hash has at least numBits
+// leading zero bits.
+func hasLeadingZeroBits(
+	hash []byte,
+	numBits int,
+) bool {
+	fullBytes := numBits / bitsPerByte
+	remainBits := numBits % bitsPerByte
+
+	for idx := range fullBytes {
+		if hash[idx] != 0 {
+			return false
+		}
+	}
+
+	if remainBits > 0 && fullBytes < len(hash) {
+		mask := byte(
+			fullByteMask << (bitsPerByte - remainBits),
+		)
+
+		if hash[fullBytes]&mask != 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
+// randomCounter generates a random hex counter string.
+func randomCounter() string {
+	counterVal, err := rand.Int(
+		rand.Reader, big.NewInt(counterSpace),
+	)
+	if err != nil {
+		// Fallback to timestamp-based counter on error.
+		return fmt.Sprintf("%x", time.Now().UnixNano())
+	}
+
+	return hex.EncodeToString(counterVal.Bytes())
+}

internal/cli/api/types.go

@@ -5,13 +5,13 @@ import "time"
 // SessionRequest is the body for POST /api/v1/session.
 type SessionRequest struct {
 	Nick     string `json:"nick"`
+	Hashcash string `json:"pow_token,omitempty"` //nolint:tagliatelle
 }
 
 // SessionResponse is the response from session creation.
 type SessionResponse struct {
 	ID   int64  `json:"id"`
 	Nick string `json:"nick"`
-	Token string `json:"token"`
 }
 
 // StateResponse is the response from GET /api/v1/state.
@@ -66,6 +66,7 @@ type ServerInfo struct {
 	Name         string `json:"name"`
 	MOTD         string `json:"motd"`
 	Version      string `json:"version"`
+	HashcashBits int    `json:"hashcash_bits"` //nolint:tagliatelle
 }
 
 // MessagesResponse wraps polling results.

internal/cli/app.go

@@ -0,0 +1,912 @@
+// Package cli implements the neoirc-cli terminal client.
+package cli
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	api "git.eeqj.de/sneak/neoirc/internal/cli/api"
+	"git.eeqj.de/sneak/neoirc/pkg/irc"
+)
+
+const (
+	splitParts  = 2
+	pollTimeout = 15
+	pollRetry   = 2 * time.Second
+	timeFormat  = "15:04"
+)
+
+// App holds the application state.
+type App struct {
+	ui     *UI
+	client *api.Client
+
+	mu        sync.Mutex
+	nick      string
+	target    string
+	connected bool
+	lastQID   int64
+	stopPoll  chan struct{}
+}
+
+// Run creates and runs the CLI application.
+func Run() {
+	app := &App{ //nolint:exhaustruct
+		ui:   NewUI(),
+		nick: "guest",
+	}
+
+	app.ui.OnInput(app.handleInput)
+	app.ui.SetStatus(app.nick, "", "disconnected")
+
+	app.ui.AddStatus(
+		"Welcome to neoirc-cli — 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)
+		os.Exit(1)
+	}
+}
+
+func (a *App) handleInput(text string) {
+	if strings.HasPrefix(text, "/") {
+		a.handleCommand(text)
+
+		return
+	}
+
+	a.mu.Lock()
+	target := a.target
+	connected := a.connected
+	a.mu.Unlock()
+
+	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{ //nolint:exhaustruct
+		Command: irc.CmdPrivmsg,
+		To:      target,
+		Body:    []string{text},
+	})
+	if err != nil {
+		a.ui.AddStatus(
+			"[red]Send error: " + err.Error(),
+		)
+
+		return
+	}
+
+	timestamp := time.Now().Format(timeFormat)
+
+	a.mu.Lock()
+	nick := a.nick
+	a.mu.Unlock()
+
+	a.ui.AddLine(target, fmt.Sprintf(
+		"[gray]%s [green]<%s>[white] %s",
+		timestamp, nick, text,
+	))
+}
+
+func (a *App) handleCommand(text string) {
+	parts := strings.SplitN(text, " ", splitParts)
+	cmd := strings.ToLower(parts[0])
+
+	args := ""
+	if len(parts) > 1 {
+		args = parts[1]
+	}
+
+	a.dispatchCommand(cmd, args)
+}
+
+func (a *App) dispatchCommand(cmd, args string) {
+	switch cmd {
+	case "/connect":
+		a.cmdConnect(args)
+	case "/nick":
+		a.cmdNick(args)
+	case "/join":
+		a.cmdJoin(args)
+	case "/part":
+		a.cmdPart(args)
+	case "/msg":
+		a.cmdMsg(args)
+	case "/query":
+		a.cmdQuery(args)
+	case "/topic":
+		a.cmdTopic(args)
+	case "/window", "/w":
+		a.cmdWindow(args)
+	case "/quit":
+		a.cmdQuit()
+	case "/help":
+		a.cmdHelp()
+	default:
+		a.dispatchInfoCommand(cmd, args)
+	}
+}
+
+func (a *App) dispatchInfoCommand(cmd, args string) {
+	switch cmd {
+	case "/names":
+		a.cmdNames()
+	case "/list":
+		a.cmdList()
+	case "/motd":
+		a.cmdMotd()
+	case "/who":
+		a.cmdWho(args)
+	case "/whois":
+		a.cmdWhois(args)
+	default:
+		a.ui.AddStatus(
+			"[red]Unknown command: " + cmd,
+		)
+	}
+}
+
+func (a *App) cmdConnect(serverURL string) {
+	if serverURL == "" {
+		a.ui.AddStatus(
+			"[red]Usage: /connect <server-url>",
+		)
+
+		return
+	}
+
+	serverURL = strings.TrimRight(serverURL, "/")
+
+	a.ui.AddStatus("Connecting to " + 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,
+		))
+
+		return
+	}
+
+	a.mu.Lock()
+	a.client = client
+	a.nick = resp.Nick
+	a.connected = true
+	a.lastQID = 0
+	a.mu.Unlock()
+
+	a.ui.AddStatus(fmt.Sprintf(
+		"[green]Connected! Nick: %s, Session: %d",
+		resp.Nick, resp.ID,
+	))
+	a.ui.SetStatus(resp.Nick, "", "connected")
+
+	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()
+
+	if !connected {
+		a.mu.Lock()
+		a.nick = nick
+		a.mu.Unlock()
+
+		a.ui.AddStatus(
+			"Nick set to " + nick +
+				" (will be used on connect)",
+		)
+
+		return
+	}
+
+	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
+		Command: irc.CmdNick,
+		Body:    []string{nick},
+	})
+	if err != nil {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[red]Nick change failed: %v", err,
+		))
+
+		return
+	}
+
+	a.mu.Lock()
+	a.nick = nick
+	target := a.target
+	a.mu.Unlock()
+
+	a.ui.SetStatus(nick, target, "connected")
+	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
+	}
+
+	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
+	}
+
+	a.mu.Lock()
+	a.target = channel
+	nick := a.nick
+	a.mu.Unlock()
+
+	a.ui.SwitchToBuffer(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,
+		"[yellow]*** Left "+channel,
+	)
+
+	a.mu.Lock()
+	if a.target == channel {
+		a.target = ""
+	}
+
+	nick := a.nick
+	a.mu.Unlock()
+
+	a.ui.SwitchBuffer(0)
+	a.ui.SetStatus(nick, "", "connected")
+}
+
+func (a *App) cmdMsg(args string) {
+	parts := strings.SplitN(args, " ", splitParts)
+	if len(parts) < splitParts {
+		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{ //nolint:exhaustruct
+		Command: irc.CmdPrivmsg,
+		To:      target,
+		Body:    []string{text},
+	})
+	if err != nil {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[red]Send failed: %v", err,
+		))
+
+		return
+	}
+
+	timestamp := time.Now().Format(timeFormat)
+
+	a.ui.AddLine(target, fmt.Sprintf(
+		"[gray]%s [green]<%s>[white] %s",
+		timestamp, nick, text,
+	))
+}
+
+func (a *App) cmdQuery(nick string) {
+	if nick == "" {
+		a.ui.AddStatus(
+			"[red]Usage: /query <nick>",
+		)
+
+		return
+	}
+
+	a.mu.Lock()
+	a.target = nick
+	myNick := a.nick
+	a.mu.Unlock()
+
+	a.ui.SwitchToBuffer(nick)
+	a.ui.SetStatus(myNick, nick, "connected")
+}
+
+func (a *App) cmdTopic(args string) {
+	a.mu.Lock()
+	target := a.target
+	connected := a.connected
+	a.mu.Unlock()
+
+	if !connected {
+		a.ui.AddStatus("[red]Not connected")
+
+		return
+	}
+
+	if !strings.HasPrefix(target, "#") {
+		a.ui.AddStatus("[red]Not in a channel")
+
+		return
+	}
+
+	if args == "" {
+		err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
+			Command: irc.CmdTopic,
+			To:      target,
+		})
+		if err != nil {
+			a.ui.AddStatus(fmt.Sprintf(
+				"[red]Topic query failed: %v", err,
+			))
+		}
+
+		return
+	}
+
+	err := a.client.SendMessage(&api.Message{ //nolint:exhaustruct
+		Command: irc.CmdTopic,
+		To:      target,
+		Body:    []string{args},
+	})
+	if err != nil {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[red]Topic set failed: %v", err,
+		))
+	}
+}
+
+func (a *App) cmdNames() {
+	a.mu.Lock()
+	target := a.target
+	connected := a.connected
+	a.mu.Unlock()
+
+	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
+	}
+
+	a.ui.AddLine(target, fmt.Sprintf(
+		"[cyan]*** Members of %s: %s",
+		target, strings.Join(members, " "),
+	))
+}
+
+func (a *App) cmdList() {
+	a.mu.Lock()
+	connected := a.connected
+	a.mu.Unlock()
+
+	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) cmdMotd() {
+	a.mu.Lock()
+	connected := a.connected
+	a.mu.Unlock()
+
+	if !connected {
+		a.ui.AddStatus("[red]Not connected")
+
+		return
+	}
+
+	err := a.client.SendMessage(
+		&api.Message{Command: irc.CmdMotd}, //nolint:exhaustruct
+	)
+	if err != nil {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[red]MOTD failed: %v", err,
+		))
+	}
+}
+
+func (a *App) cmdWho(args string) {
+	a.mu.Lock()
+	connected := a.connected
+	target := a.target
+	a.mu.Unlock()
+
+	if !connected {
+		a.ui.AddStatus("[red]Not connected")
+
+		return
+	}
+
+	channel := args
+	if channel == "" {
+		channel = target
+	}
+
+	if channel == "" ||
+		!strings.HasPrefix(channel, "#") {
+		a.ui.AddStatus(
+			"[red]Usage: /who #channel",
+		)
+
+		return
+	}
+
+	err := a.client.SendMessage(
+		&api.Message{ //nolint:exhaustruct
+			Command: irc.CmdWho, To: channel,
+		},
+	)
+	if err != nil {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[red]WHO failed: %v", err,
+		))
+	}
+}
+
+func (a *App) cmdWhois(args string) {
+	a.mu.Lock()
+	connected := a.connected
+	a.mu.Unlock()
+
+	if !connected {
+		a.ui.AddStatus("[red]Not connected")
+
+		return
+	}
+
+	if args == "" {
+		a.ui.AddStatus(
+			"[red]Usage: /whois <nick>",
+		)
+
+		return
+	}
+
+	err := a.client.SendMessage(
+		&api.Message{ //nolint:exhaustruct
+			Command: irc.CmdWhois, To: args,
+		},
+	)
+	if err != nil {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[red]WHOIS failed: %v", err,
+		))
+	}
+}
+
+func (a *App) cmdWindow(args string) {
+	if args == "" {
+		a.ui.AddStatus(
+			"[red]Usage: /window <number>",
+		)
+
+		return
+	}
+
+	var bufIndex int
+
+	_, _ = fmt.Sscanf(args, "%d", &bufIndex)
+
+	a.ui.SwitchBuffer(bufIndex)
+
+	a.mu.Lock()
+	nick := a.nick
+	a.mu.Unlock()
+
+	if bufIndex >= 0 && bufIndex < a.ui.BufferCount() {
+		buf := a.ui.buffers[bufIndex]
+		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")
+		}
+	}
+}
+
+func (a *App) cmdQuit() {
+	a.mu.Lock()
+
+	if a.connected && a.client != nil {
+		_ = a.client.SendMessage(
+			&api.Message{Command: irc.CmdQuit}, //nolint:exhaustruct
+		)
+	}
+
+	if a.stopPoll != nil {
+		close(a.stopPoll)
+	}
+
+	a.mu.Unlock()
+	a.ui.Stop()
+}
+
+func (a *App) cmdHelp() {
+	help := []string{
+		"[cyan]*** neoirc-cli commands:",
+		"  /connect <url>  — Connect to server",
+		"  /nick <name>    — Change nickname",
+		"  /join #channel  — Join channel",
+		"  /part [#chan]    — Leave channel",
+		"  /msg <nick> <text> — Send DM",
+		"  /query <nick>   — Open DM window",
+		"  /topic [text]   — View/set topic",
+		"  /names          — List channel members",
+		"  /list           — List channels",
+		"  /who [#channel] — List users in channel",
+		"  /whois <nick>   — Show user info",
+		"  /motd           — Show message of the day",
+		"  /window <n>     — Switch buffer",
+		"  /quit           — Disconnect and exit",
+		"  /help           — This help",
+		"  Plain text sends to current target.",
+	}
+
+	for _, line := range help {
+		a.ui.AddStatus(line)
+	}
+}
+
+// pollLoop long-polls for messages in the background.
+func (a *App) pollLoop() {
+	for {
+		select {
+		case <-a.stopPoll:
+			return
+		default:
+		}
+
+		a.mu.Lock()
+		client := a.client
+		lastQID := a.lastQID
+		a.mu.Unlock()
+
+		if client == nil {
+			return
+		}
+
+		result, err := client.PollMessages(
+			lastQID, pollTimeout,
+		)
+		if err != nil {
+			time.Sleep(pollRetry)
+
+			continue
+		}
+
+		if result.LastID > 0 {
+			a.mu.Lock()
+			a.lastQID = result.LastID
+			a.mu.Unlock()
+		}
+
+		for i := range result.Messages {
+			a.handleServerMessage(&result.Messages[i])
+		}
+	}
+}
+
+func (a *App) handleServerMessage(msg *api.Message) {
+	timestamp := a.formatTS(msg)
+
+	a.mu.Lock()
+	myNick := a.nick
+	a.mu.Unlock()
+
+	switch msg.Command {
+	case irc.CmdPrivmsg:
+		a.handlePrivmsgEvent(msg, timestamp, myNick)
+	case irc.CmdJoin:
+		a.handleJoinEvent(msg, timestamp)
+	case irc.CmdPart:
+		a.handlePartEvent(msg, timestamp)
+	case irc.CmdQuit:
+		a.handleQuitEvent(msg, timestamp)
+	case irc.CmdNick:
+		a.handleNickEvent(msg, timestamp, myNick)
+	case irc.CmdNotice:
+		a.handleNoticeEvent(msg, timestamp)
+	case irc.CmdTopic:
+		a.handleTopicEvent(msg, timestamp)
+	default:
+		a.handleDefaultEvent(msg, timestamp)
+	}
+}
+
+func (a *App) formatTS(msg *api.Message) string {
+	if msg.TS != "" {
+		return msg.ParseTS().UTC().Format(timeFormat)
+	}
+
+	return time.Now().Format(timeFormat)
+}
+
+func (a *App) handlePrivmsgEvent(
+	msg *api.Message, timestamp, myNick string,
+) {
+	lines := msg.BodyLines()
+	text := strings.Join(lines, " ")
+
+	if msg.From == myNick {
+		return
+	}
+
+	target := msg.To
+	if !strings.HasPrefix(target, "#") {
+		target = msg.From
+	}
+
+	a.ui.AddLine(target, fmt.Sprintf(
+		"[gray]%s [green]<%s>[white] %s",
+		timestamp, msg.From, text,
+	))
+}
+
+func (a *App) handleJoinEvent(
+	msg *api.Message, timestamp string,
+) {
+	if msg.To == "" {
+		return
+	}
+
+	a.ui.AddLine(msg.To, fmt.Sprintf(
+		"[gray]%s [yellow]*** %s has joined %s",
+		timestamp, msg.From, msg.To,
+	))
+}
+
+func (a *App) handlePartEvent(
+	msg *api.Message, timestamp string,
+) {
+	if msg.To == "" {
+		return
+	}
+
+	lines := msg.BodyLines()
+	reason := strings.Join(lines, " ")
+
+	if reason != "" {
+		a.ui.AddLine(msg.To, fmt.Sprintf(
+			"[gray]%s [yellow]*** %s has left %s (%s)",
+			timestamp, msg.From, msg.To, reason,
+		))
+	} else {
+		a.ui.AddLine(msg.To, fmt.Sprintf(
+			"[gray]%s [yellow]*** %s has left %s",
+			timestamp, msg.From, msg.To,
+		))
+	}
+}
+
+func (a *App) handleQuitEvent(
+	msg *api.Message, timestamp string,
+) {
+	lines := msg.BodyLines()
+	reason := strings.Join(lines, " ")
+
+	if reason != "" {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[gray]%s [yellow]*** %s has quit (%s)",
+			timestamp, msg.From, reason,
+		))
+	} else {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[gray]%s [yellow]*** %s has quit",
+			timestamp, msg.From,
+		))
+	}
+}
+
+func (a *App) handleNickEvent(
+	msg *api.Message, timestamp, 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",
+		timestamp, msg.From, newNick,
+	))
+}
+
+func (a *App) handleNoticeEvent(
+	msg *api.Message, timestamp string,
+) {
+	lines := msg.BodyLines()
+	text := strings.Join(lines, " ")
+
+	a.ui.AddStatus(fmt.Sprintf(
+		"[gray]%s [magenta]--%s-- %s",
+		timestamp, msg.From, text,
+	))
+}
+
+func (a *App) handleTopicEvent(
+	msg *api.Message, timestamp 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",
+		timestamp, msg.From, text,
+	))
+}
+
+func (a *App) handleDefaultEvent(
+	msg *api.Message, timestamp string,
+) {
+	lines := msg.BodyLines()
+	text := strings.Join(lines, " ")
+
+	if text != "" {
+		a.ui.AddStatus(fmt.Sprintf(
+			"[gray]%s [white][%s] %s",
+			timestamp, msg.Command, text,
+		))
+	}
+}

internal/cli/ui.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"fmt"

internal/config/config.go

@@ -45,6 +45,7 @@ type Config struct {
 	ServerName         string
 	FederationKey      string
 	SessionIdleTimeout string
+	HashcashBits       int
 	params             *Params
 	log                *slog.Logger
 }
@@ -76,6 +77,7 @@ func New(
 	viper.SetDefault("SERVER_NAME", "")
 	viper.SetDefault("FEDERATION_KEY", "")
 	viper.SetDefault("SESSION_IDLE_TIMEOUT", "720h")
+	viper.SetDefault("NEOIRC_HASHCASH_BITS", "20")
 
 	err := viper.ReadInConfig()
 	if err != nil {
@@ -101,6 +103,7 @@ func New(
 		ServerName:         viper.GetString("SERVER_NAME"),
 		FederationKey:      viper.GetString("FEDERATION_KEY"),
 		SessionIdleTimeout: viper.GetString("SESSION_IDLE_TIMEOUT"),
+		HashcashBits:       viper.GetInt("NEOIRC_HASHCASH_BITS"),
 		log:                log,
 		params:             &params,
 	}

internal/db/auth.go

@@ -16,80 +16,28 @@ var errNoPassword = errors.New(
 	"account has no password set",
 )
 
-// RegisterUser creates a session with a hashed password
+// SetPassword sets a bcrypt-hashed password on a session,
-// and returns session ID, client ID, and token.
+// enabling multi-client login via POST /api/v1/login.
-func (database *Database) RegisterUser(
+func (database *Database) SetPassword(
 	ctx context.Context,
-	nick, password string,
+	sessionID int64,
-) (int64, int64, string, error) {
+	password string,
+) error {
 	hash, err := bcrypt.GenerateFromPassword(
 		[]byte(password), bcryptCost,
 	)
 	if err != nil {
-		return 0, 0, "", fmt.Errorf(
+		return fmt.Errorf("hash password: %w", err)
-			"hash password: %w", err,
-		)
 	}
 
-	sessionUUID := uuid.New().String()
+	_, err = database.conn.ExecContext(ctx,
-	clientUUID := uuid.New().String()
+		"UPDATE sessions SET password_hash = ? WHERE id = ?",
-
+		string(hash), sessionID)
-	token, err := generateToken()
 	if err != nil {
-		return 0, 0, "", err
+		return fmt.Errorf("set password: %w", err)
 	}
 
-	now := time.Now()
+	return nil
-
-	transaction, err := database.conn.BeginTx(ctx, nil)
-	if err != nil {
-		return 0, 0, "", fmt.Errorf(
-			"begin tx: %w", err,
-		)
-	}
-
-	res, err := transaction.ExecContext(ctx,
-		`INSERT INTO sessions
-		 (uuid, nick, password_hash,
-		  created_at, last_seen)
-		 VALUES (?, ?, ?, ?, ?)`,
-		sessionUUID, nick, string(hash), now, now)
-	if err != nil {
-		_ = transaction.Rollback()
-
-		return 0, 0, "", fmt.Errorf(
-			"create session: %w", err,
-		)
-	}
-
-	sessionID, _ := res.LastInsertId()
-
-	tokenHash := hashToken(token)
-
-	clientRes, err := transaction.ExecContext(ctx,
-		`INSERT INTO clients
-		 (uuid, session_id, token,
-		  created_at, last_seen)
-		 VALUES (?, ?, ?, ?, ?)`,
-		clientUUID, sessionID, tokenHash, now, now)
-	if err != nil {
-		_ = transaction.Rollback()
-
-		return 0, 0, "", fmt.Errorf(
-			"create client: %w", err,
-		)
-	}
-
-	clientID, _ := clientRes.LastInsertId()
-
-	err = transaction.Commit()
-	if err != nil {
-		return 0, 0, "", fmt.Errorf(
-			"commit registration: %w", err,
-		)
-	}
-
-	return sessionID, clientID, token, nil
 }
 
 // LoginUser verifies a nick/password and creates a new

internal/db/auth_test.go

@@ -6,63 +6,65 @@ import (
 	_ "modernc.org/sqlite"
 )
 
-func TestRegisterUser(t *testing.T) {
+func TestSetPassword(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	sessionID, clientID, token, err :=
+	sessionID, _, _, err :=
-		database.RegisterUser(ctx, "reguser", "password123")
+		database.CreateSession(ctx, "passuser")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	if sessionID == 0 || clientID == 0 || token == "" {
+	err = database.SetPassword(
+		ctx, sessionID, "password123",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Verify we can now log in with the password.
+	loginSID, loginCID, loginToken, err :=
+		database.LoginUser(ctx, "passuser", "password123")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if loginSID == 0 || loginCID == 0 || loginToken == "" {
 		t.Fatal("expected valid ids and token")
 	}
-
-	// Verify session works via token lookup.
-	sid, cid, nick, err :=
-		database.GetSessionByToken(ctx, token)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if sid != sessionID || cid != clientID {
-		t.Fatal("session/client id mismatch")
-	}
-
-	if nick != "reguser" {
-		t.Fatalf("expected reguser, got %s", nick)
-	}
 }
 
-func TestRegisterUserDuplicateNick(t *testing.T) {
+func TestSetPasswordThenWrongLogin(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	regSID, regCID, regToken, err :=
+	sessionID, _, _, err :=
-		database.RegisterUser(ctx, "dupnick", "password123")
+		database.CreateSession(ctx, "wrongpw")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	_ = regSID
+	err = database.SetPassword(
-	_ = regCID
+		ctx, sessionID, "correctpass",
-	_ = regToken
+	)
-
+	if err != nil {
-	dupSID, dupCID, dupToken, dupErr :=
+		t.Fatal(err)
-		database.RegisterUser(ctx, "dupnick", "other12345")
-	if dupErr == nil {
-		t.Fatal("expected error for duplicate nick")
 	}
 
-	_ = dupSID
+	loginSID, loginCID, loginToken, loginErr :=
-	_ = dupCID
+		database.LoginUser(ctx, "wrongpw", "wrongpass12")
-	_ = dupToken
+	if loginErr == nil {
+		t.Fatal("expected error for wrong password")
+	}
+
+	_ = loginSID
+	_ = loginCID
+	_ = loginToken
 }
 
 func TestLoginUser(t *testing.T) {
@@ -71,23 +73,26 @@ func TestLoginUser(t *testing.T) {
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	regSID, regCID, regToken, err :=
+	sessionID, _, _, err :=
-		database.RegisterUser(ctx, "loginuser", "mypassword")
+		database.CreateSession(ctx, "loginuser")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	_ = regSID
+	err = database.SetPassword(
-	_ = regCID
+		ctx, sessionID, "mypassword",
-	_ = regToken
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
 
-	sessionID, clientID, token, err :=
+	loginSID, loginCID, token, err :=
 		database.LoginUser(ctx, "loginuser", "mypassword")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	if sessionID == 0 || clientID == 0 || token == "" {
+	if loginSID == 0 || loginCID == 0 || token == "" {
 		t.Fatal("expected valid ids and token")
 	}
 
@@ -103,33 +108,6 @@ func TestLoginUser(t *testing.T) {
 	}
 }
 
-func TestLoginUserWrongPassword(t *testing.T) {
-	t.Parallel()
-
-	database := setupTestDB(t)
-	ctx := t.Context()
-
-	regSID, regCID, regToken, err :=
-		database.RegisterUser(ctx, "wrongpw", "correctpass")
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	_ = regSID
-	_ = regCID
-	_ = regToken
-
-	loginSID, loginCID, loginToken, loginErr :=
-		database.LoginUser(ctx, "wrongpw", "wrongpass12")
-	if loginErr == nil {
-		t.Fatal("expected error for wrong password")
-	}
-
-	_ = loginSID
-	_ = loginCID
-	_ = loginToken
-}
-
 func TestLoginUserNoPassword(t *testing.T) {
 	t.Parallel()
 

internal/db/queries.go

@@ -11,7 +11,7 @@ import (
 	"strconv"
 	"time"
 
-	"git.eeqj.de/sneak/neoirc/internal/irc"
+	"git.eeqj.de/sneak/neoirc/pkg/irc"
 	"github.com/google/uuid"
 )
 
@@ -746,8 +746,8 @@ func scanMessages(
 			code, _ := strconv.Atoi(msg.Command)
 			msg.Code = code
 
-			if name := irc.Name(code); name != "" {
+			if mt, err := irc.FromInt(code); err == nil {
-				msg.Command = name
+				msg.Command = mt.Name()
 			}
 		}
 
@@ -1266,3 +1266,149 @@ func (database *Database) PruneOldMessages(
 
 	return deleted, nil
 }
+
+// GetClientCount returns the total number of clients.
+func (database *Database) GetClientCount(
+	ctx context.Context,
+) (int64, error) {
+	var count int64
+
+	err := database.conn.QueryRowContext(
+		ctx,
+		"SELECT COUNT(*) FROM clients",
+	).Scan(&count)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"get client count: %w", err,
+		)
+	}
+
+	return count, nil
+}
+
+// GetQueueEntryCount returns the total number of entries
+// in the client output queues.
+func (database *Database) GetQueueEntryCount(
+	ctx context.Context,
+) (int64, error) {
+	var count int64
+
+	err := database.conn.QueryRowContext(
+		ctx,
+		"SELECT COUNT(*) FROM client_queues",
+	).Scan(&count)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"get queue entry count: %w", err,
+		)
+	}
+
+	return count, nil
+}
+
+// GetChannelHashcashBits returns the hashcash difficulty
+// requirement for a channel. Returns 0 if not set.
+func (database *Database) GetChannelHashcashBits(
+	ctx context.Context,
+	channelID int64,
+) (int, error) {
+	var bits int
+
+	err := database.conn.QueryRowContext(
+		ctx,
+		"SELECT hashcash_bits FROM channels WHERE id = ?",
+		channelID,
+	).Scan(&bits)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"get channel hashcash bits: %w", err,
+		)
+	}
+
+	return bits, nil
+}
+
+// SetChannelHashcashBits sets the hashcash difficulty
+// requirement for a channel. A value of 0 disables the
+// requirement.
+func (database *Database) SetChannelHashcashBits(
+	ctx context.Context,
+	channelID int64,
+	bits int,
+) error {
+	_, err := database.conn.ExecContext(ctx,
+		`UPDATE channels
+		 SET hashcash_bits = ?, updated_at = ?
+		 WHERE id = ?`,
+		bits, time.Now(), channelID)
+	if err != nil {
+		return fmt.Errorf(
+			"set channel hashcash bits: %w", err,
+		)
+	}
+
+	return nil
+}
+
+// RecordSpentHashcash stores a spent hashcash stamp hash
+// for replay prevention.
+func (database *Database) RecordSpentHashcash(
+	ctx context.Context,
+	stampHash string,
+) error {
+	_, err := database.conn.ExecContext(ctx,
+		`INSERT OR IGNORE INTO spent_hashcash
+		 (stamp_hash, created_at)
+		 VALUES (?, ?)`,
+		stampHash, time.Now())
+	if err != nil {
+		return fmt.Errorf(
+			"record spent hashcash: %w", err,
+		)
+	}
+
+	return nil
+}
+
+// IsHashcashSpent checks whether a hashcash stamp hash
+// has already been used.
+func (database *Database) IsHashcashSpent(
+	ctx context.Context,
+	stampHash string,
+) (bool, error) {
+	var count int
+
+	err := database.conn.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM spent_hashcash
+		 WHERE stamp_hash = ?`,
+		stampHash,
+	).Scan(&count)
+	if err != nil {
+		return false, fmt.Errorf(
+			"check spent hashcash: %w", err,
+		)
+	}
+
+	return count > 0, nil
+}
+
+// PruneSpentHashcash deletes spent hashcash tokens older
+// than the cutoff and returns the number of rows removed.
+func (database *Database) PruneSpentHashcash(
+	ctx context.Context,
+	cutoff time.Time,
+) (int64, error) {
+	res, err := database.conn.ExecContext(ctx,
+		"DELETE FROM spent_hashcash WHERE created_at < ?",
+		cutoff,
+	)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"prune spent hashcash: %w", err,
+		)
+	}
+
+	deleted, _ := res.RowsAffected()
+
+	return deleted, nil
+}

internal/db/schema/001_initial.sql

@@ -33,6 +33,7 @@ CREATE TABLE IF NOT EXISTS channels (
     topic TEXT NOT NULL DEFAULT '',
     topic_set_by TEXT NOT NULL DEFAULT '',
     topic_set_at DATETIME,
+    hashcash_bits INTEGER NOT NULL DEFAULT 0,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
 );
@@ -61,6 +62,14 @@ CREATE TABLE IF NOT EXISTS messages (
 CREATE INDEX IF NOT EXISTS idx_messages_to_id ON messages(msg_to, id);
 CREATE INDEX IF NOT EXISTS idx_messages_created ON messages(created_at);
 
+-- Spent hashcash tokens for replay prevention (1-year TTL)
+CREATE TABLE IF NOT EXISTS spent_hashcash (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    stamp_hash TEXT NOT NULL UNIQUE,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+CREATE INDEX IF NOT EXISTS idx_spent_hashcash_created ON spent_hashcash(created_at);
+
 -- Per-client message queues for fan-out delivery
 CREATE TABLE IF NOT EXISTS client_queues (
     id INTEGER PRIMARY KEY AUTOINCREMENT,

internal/handlers/api.go

@@ -3,6 +3,7 @@ package handlers
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"regexp"
@@ -11,8 +12,14 @@ import (
 	"time"
 
 	"git.eeqj.de/sneak/neoirc/internal/db"
-	"git.eeqj.de/sneak/neoirc/internal/irc"
+	"git.eeqj.de/sneak/neoirc/internal/hashcash"
-	"github.com/go-chi/chi"
+	"git.eeqj.de/sneak/neoirc/pkg/irc"
+	"github.com/go-chi/chi/v5"
+)
+
+var (
+	errHashcashRequired = errors.New("hashcash required")
+	errHashcashReused   = errors.New("hashcash reused")
 )
 
 var validNickRe = regexp.MustCompile(
@@ -29,6 +36,7 @@ const (
 	defaultMaxBodySize = 4096
 	defaultHistLimit   = 50
 	maxHistLimit       = 500
+	authCookieName     = "neoirc_auth"
 )
 
 func (hdlr *Handlers) maxBodySize() int64 {
@@ -39,23 +47,18 @@ func (hdlr *Handlers) maxBodySize() int64 {
 	return defaultMaxBodySize
 }
 
-// authSession extracts the session from the client token.
+// authSession extracts the session from the auth cookie.
 func (hdlr *Handlers) authSession(
 	request *http.Request,
 ) (int64, int64, string, error) {
-	auth := request.Header.Get("Authorization")
+	cookie, err := request.Cookie(authCookieName)
-	if !strings.HasPrefix(auth, "Bearer ") {
+	if err != nil || cookie.Value == "" {
-		return 0, 0, "", errUnauthorized
-	}
-
-	token := strings.TrimPrefix(auth, "Bearer ")
-	if token == "" {
 		return 0, 0, "", errUnauthorized
 	}
 
 	sessionID, clientID, nick, err :=
 		hdlr.params.Database.GetSessionByToken(
-			request.Context(), token,
+			request.Context(), cookie.Value,
 		)
 	if err != nil {
 		return 0, 0, "", fmt.Errorf("auth: %w", err)
@@ -64,6 +67,46 @@ func (hdlr *Handlers) authSession(
 	return sessionID, clientID, nick, nil
 }
 
+// setAuthCookie sets the authentication cookie on the
+// response.
+func (hdlr *Handlers) setAuthCookie(
+	writer http.ResponseWriter,
+	request *http.Request,
+	token string,
+) {
+	secure := request.TLS != nil ||
+		request.Header.Get("X-Forwarded-Proto") == "https"
+
+	http.SetCookie(writer, &http.Cookie{ //nolint:exhaustruct // optional fields
+		Name:     authCookieName,
+		Value:    token,
+		Path:     "/",
+		HttpOnly: true,
+		Secure:   secure,
+		SameSite: http.SameSiteStrictMode,
+	})
+}
+
+// clearAuthCookie removes the authentication cookie from
+// the client.
+func (hdlr *Handlers) clearAuthCookie(
+	writer http.ResponseWriter,
+	request *http.Request,
+) {
+	secure := request.TLS != nil ||
+		request.Header.Get("X-Forwarded-Proto") == "https"
+
+	http.SetCookie(writer, &http.Cookie{ //nolint:exhaustruct // optional fields
+		Name:     authCookieName,
+		Value:    "",
+		Path:     "/",
+		HttpOnly: true,
+		Secure:   secure,
+		SameSite: http.SameSiteStrictMode,
+		MaxAge:   -1,
+	})
+}
+
 func (hdlr *Handlers) requireAuth(
 	writer http.ResponseWriter,
 	request *http.Request,
@@ -88,10 +131,11 @@ func (hdlr *Handlers) fanOut(
 	request *http.Request,
 	command, from, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 	sessionIDs []int64,
 ) (string, error) {
 	dbID, msgUUID, err := hdlr.params.Database.InsertMessage(
-		request.Context(), command, from, target, nil, body, nil,
+		request.Context(), command, from, target, nil, body, meta,
 	)
 	if err != nil {
 		return "", fmt.Errorf("insert message: %w", err)
@@ -117,10 +161,11 @@ func (hdlr *Handlers) fanOutSilent(
 	request *http.Request,
 	command, from, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 	sessionIDs []int64,
 ) error {
 	_, err := hdlr.fanOut(
-		request, command, from, target, body, sessionIDs,
+		request, command, from, target, body, meta, sessionIDs,
 	)
 
 	return err
@@ -146,6 +191,7 @@ func (hdlr *Handlers) handleCreateSession(
 ) {
 	type createRequest struct {
 		Nick     string `json:"nick"`
+		Hashcash string `json:"pow_token,omitempty"` //nolint:tagliatelle
 	}
 
 	var payload createRequest
@@ -161,6 +207,32 @@ func (hdlr *Handlers) handleCreateSession(
 		return
 	}
 
+	// Validate hashcash proof-of-work if configured.
+	if hdlr.params.Config.HashcashBits > 0 {
+		if payload.Hashcash == "" {
+			hdlr.respondError(
+				writer, request,
+				"hashcash proof-of-work required",
+				http.StatusPaymentRequired,
+			)
+
+			return
+		}
+
+		err = hdlr.hashcashVal.Validate(
+			payload.Hashcash, hdlr.params.Config.HashcashBits,
+		)
+		if err != nil {
+			hdlr.respondError(
+				writer, request,
+				"invalid hashcash stamp: "+err.Error(),
+				http.StatusPaymentRequired,
+			)
+
+			return
+		}
+	}
+
 	payload.Nick = strings.TrimSpace(payload.Nick)
 
 	if !validNickRe.MatchString(payload.Nick) {
@@ -185,12 +257,16 @@ func (hdlr *Handlers) handleCreateSession(
 		return
 	}
 
+	hdlr.stats.IncrSessions()
+	hdlr.stats.IncrConnections()
+
 	hdlr.deliverMOTD(request, clientID, sessionID, payload.Nick)
 
+	hdlr.setAuthCookie(writer, request, token)
+
 	hdlr.respondJSON(writer, request, map[string]any{
 		"id":   sessionID,
 		"nick": payload.Nick,
-		"token": token,
 	}, http.StatusCreated)
 }
 
@@ -264,7 +340,7 @@ func (hdlr *Handlers) deliverWelcome(
 		[]string{
 			"CHANTYPES=#",
 			"NICKLEN=32",
-			"CHANMODES=,,," + "imnst",
+			"CHANMODES=,,H," + "imnst",
 			"NETWORK=neoirc",
 			"CASEMAPPING=ascii",
 		},
@@ -397,12 +473,12 @@ func (hdlr *Handlers) serverName() string {
 func (hdlr *Handlers) enqueueNumeric(
 	ctx context.Context,
 	clientID int64,
-	code int,
+	code irc.IRCMessageType,
 	nick string,
 	params []string,
 	text string,
 ) {
-	command := fmt.Sprintf("%03d", code)
+	command := code.Code()
 
 	body, err := json.Marshal([]string{text})
 	if err != nil {
@@ -795,7 +871,7 @@ func (hdlr *Handlers) HandleSendCommand() http.HandlerFunc {
 			writer, request,
 			sessionID, clientID, nick,
 			payload.Command, payload.To,
-			payload.Body, bodyLines,
+			payload.Body, payload.Meta, bodyLines,
 		)
 	}
 }
@@ -806,6 +882,7 @@ func (hdlr *Handlers) dispatchCommand(
 	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 	bodyLines func() []string,
 ) {
 	switch command {
@@ -818,7 +895,7 @@ func (hdlr *Handlers) dispatchCommand(
 		hdlr.handlePrivmsg(
 			writer, request,
 			sessionID, clientID, nick,
-			command, target, body, bodyLines,
+			command, target, body, meta, bodyLines,
 		)
 	case irc.CmdJoin:
 		hdlr.handleJoin(
@@ -835,6 +912,11 @@ func (hdlr *Handlers) dispatchCommand(
 			writer, request,
 			sessionID, clientID, nick, bodyLines,
 		)
+	case irc.CmdPass:
+		hdlr.handlePass(
+			writer, request,
+			sessionID, clientID, nick, bodyLines,
+		)
 	case irc.CmdTopic:
 		hdlr.handleTopic(
 			writer, request,
@@ -919,6 +1001,7 @@ func (hdlr *Handlers) handlePrivmsg(
 	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 	bodyLines func() []string,
 ) {
 	if target == "" {
@@ -950,11 +1033,13 @@ func (hdlr *Handlers) handlePrivmsg(
 		return
 	}
 
+	hdlr.stats.IncrMessages()
+
 	if strings.HasPrefix(target, "#") {
 		hdlr.handleChannelMsg(
 			writer, request,
 			sessionID, clientID, nick,
-			command, target, body,
+			command, target, body, meta,
 		)
 
 		return
@@ -963,7 +1048,7 @@ func (hdlr *Handlers) handlePrivmsg(
 	hdlr.handleDirectMsg(
 		writer, request,
 		sessionID, clientID, nick,
-		command, target, body,
+		command, target, body, meta,
 	)
 }
 
@@ -973,7 +1058,7 @@ func (hdlr *Handlers) respondIRCError(
 	writer http.ResponseWriter,
 	request *http.Request,
 	clientID, sessionID int64,
-	code int,
+	code irc.IRCMessageType,
 	nick string,
 	params []string,
 	text string,
@@ -994,6 +1079,7 @@ func (hdlr *Handlers) handleChannelMsg(
 	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 ) {
 	chID, err := hdlr.params.Database.GetChannelByName(
 		request.Context(), target,
@@ -1034,9 +1120,172 @@ func (hdlr *Handlers) handleChannelMsg(
 		return
 	}
 
-	hdlr.sendChannelMsg(
+	hashcashErr := hdlr.validateChannelHashcash(
-		writer, request, command, nick, target, body, chID,
+		request, clientID, sessionID,
+		writer, nick, target, body, meta, chID,
 	)
+	if hashcashErr != nil {
+		return
+	}
+
+	hdlr.sendChannelMsg(
+		writer, request, command, nick, target,
+		body, meta, chID,
+	)
+}
+
+// validateChannelHashcash checks whether the channel
+// requires hashcash proof-of-work for messages and
+// validates the stamp from the message meta field.
+// Returns nil on success or if the channel has no
+// hashcash requirement. On failure, it sends the
+// appropriate IRC error and returns a non-nil error.
+func (hdlr *Handlers) validateChannelHashcash(
+	request *http.Request,
+	clientID, sessionID int64,
+	writer http.ResponseWriter,
+	nick, target string,
+	body json.RawMessage,
+	meta json.RawMessage,
+	chID int64,
+) error {
+	ctx := request.Context()
+
+	bits, bitsErr := hdlr.params.Database.GetChannelHashcashBits(
+		ctx, chID,
+	)
+	if bitsErr != nil {
+		hdlr.log.Error(
+			"get channel hashcash bits", "error", bitsErr,
+		)
+		hdlr.respondError(
+			writer, request,
+			"internal error",
+			http.StatusInternalServerError,
+		)
+
+		return fmt.Errorf("channel hashcash bits: %w", bitsErr)
+	}
+
+	if bits <= 0 {
+		return nil
+	}
+
+	stamp := hdlr.extractHashcashFromMeta(meta)
+	if stamp == "" {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrCannotSendToChan, nick, []string{target},
+			"Channel requires hashcash proof-of-work",
+		)
+
+		return errHashcashRequired
+	}
+
+	return hdlr.verifyChannelStamp(
+		request, writer,
+		clientID, sessionID,
+		nick, target, body, stamp, bits,
+	)
+}
+
+// verifyChannelStamp validates a channel hashcash stamp
+// and checks for replay attacks.
+func (hdlr *Handlers) verifyChannelStamp(
+	request *http.Request,
+	writer http.ResponseWriter,
+	clientID, sessionID int64,
+	nick, target string,
+	body json.RawMessage,
+	stamp string,
+	bits int,
+) error {
+	ctx := request.Context()
+	bodyHashStr := hashcash.BodyHash(body)
+
+	valErr := hdlr.channelHashcash.ValidateStamp(
+		stamp, bits, target, bodyHashStr,
+	)
+	if valErr != nil {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrCannotSendToChan, nick, []string{target},
+			"Invalid hashcash: "+valErr.Error(),
+		)
+
+		return fmt.Errorf("channel hashcash: %w", valErr)
+	}
+
+	stampKey := hashcash.StampHash(stamp)
+
+	spent, spentErr := hdlr.params.Database.IsHashcashSpent(
+		ctx, stampKey,
+	)
+	if spentErr != nil {
+		hdlr.log.Error(
+			"check spent hashcash", "error", spentErr,
+		)
+		hdlr.respondError(
+			writer, request,
+			"internal error",
+			http.StatusInternalServerError,
+		)
+
+		return fmt.Errorf("check spent hashcash: %w", spentErr)
+	}
+
+	if spent {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrCannotSendToChan, nick, []string{target},
+			"Hashcash stamp already used",
+		)
+
+		return errHashcashReused
+	}
+
+	recordErr := hdlr.params.Database.RecordSpentHashcash(
+		ctx, stampKey,
+	)
+	if recordErr != nil {
+		hdlr.log.Error(
+			"record spent hashcash", "error", recordErr,
+		)
+	}
+
+	return nil
+}
+
+// extractHashcashFromMeta parses the meta JSON and
+// returns the hashcash stamp string, or empty string
+// if not present.
+func (hdlr *Handlers) extractHashcashFromMeta(
+	meta json.RawMessage,
+) string {
+	if len(meta) == 0 {
+		return ""
+	}
+
+	var metaMap map[string]json.RawMessage
+
+	err := json.Unmarshal(meta, &metaMap)
+	if err != nil {
+		return ""
+	}
+
+	raw, ok := metaMap["hashcash"]
+	if !ok {
+		return ""
+	}
+
+	var stamp string
+
+	err = json.Unmarshal(raw, &stamp)
+	if err != nil {
+		return ""
+	}
+
+	return stamp
 }
 
 func (hdlr *Handlers) sendChannelMsg(
@@ -1044,6 +1293,7 @@ func (hdlr *Handlers) sendChannelMsg(
 	request *http.Request,
 	command, nick, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 	chID int64,
 ) {
 	memberIDs, err := hdlr.params.Database.GetChannelMemberIDs(
@@ -1063,7 +1313,7 @@ func (hdlr *Handlers) sendChannelMsg(
 	}
 
 	msgUUID, err := hdlr.fanOut(
-		request, command, nick, target, body, memberIDs,
+		request, command, nick, target, body, meta, memberIDs,
 	)
 	if err != nil {
 		hdlr.log.Error("send message failed", "error", err)
@@ -1087,6 +1337,7 @@ func (hdlr *Handlers) handleDirectMsg(
 	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
+	meta json.RawMessage,
 ) {
 	targetSID, err := hdlr.params.Database.GetSessionByNick(
 		request.Context(), target,
@@ -1111,7 +1362,7 @@ func (hdlr *Handlers) handleDirectMsg(
 	}
 
 	msgUUID, err := hdlr.fanOut(
-		request, command, nick, target, body, recipients,
+		request, command, nick, target, body, meta, recipients,
 	)
 	if err != nil {
 		hdlr.log.Error("send dm failed", "error", err)
@@ -1222,7 +1473,7 @@ func (hdlr *Handlers) executeJoin(
 	)
 
 	_ = hdlr.fanOutSilent(
-		request, irc.CmdJoin, nick, channel, nil, memberIDs,
+		request, irc.CmdJoin, nick, channel, nil, nil, memberIDs,
 	)
 
 	hdlr.deliverJoinNumerics(
@@ -1392,7 +1643,7 @@ func (hdlr *Handlers) handlePart(
 	)
 
 	_ = hdlr.fanOutSilent(
-		request, irc.CmdPart, nick, channel, body, memberIDs,
+		request, irc.CmdPart, nick, channel, body, nil, memberIDs,
 	)
 
 	err = hdlr.params.Database.PartChannel(
@@ -1609,6 +1860,32 @@ func (hdlr *Handlers) handleTopic(
 		return
 	}
 
+	isMember, err := hdlr.params.Database.IsChannelMember(
+		request.Context(), chID, sessionID,
+	)
+	if err != nil {
+		hdlr.log.Error(
+			"check membership failed", "error", err,
+		)
+		hdlr.respondError(
+			writer, request,
+			"internal error",
+			http.StatusInternalServerError,
+		)
+
+		return
+	}
+
+	if !isMember {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNotOnChannel, nick, []string{channel},
+			"You're not on that channel",
+		)
+
+		return
+	}
+
 	hdlr.executeTopic(
 		writer, request,
 		sessionID, clientID, nick,
@@ -1646,7 +1923,7 @@ func (hdlr *Handlers) executeTopic(
 	)
 
 	_ = hdlr.fanOutSilent(
-		request, irc.CmdTopic, nick, channel, body, memberIDs,
+		request, irc.CmdTopic, nick, channel, body, nil, memberIDs,
 	)
 
 	hdlr.enqueueNumeric(
@@ -1770,6 +2047,8 @@ func (hdlr *Handlers) handleQuit(
 		request.Context(), sessionID,
 	)
 
+	hdlr.clearAuthCookie(writer, request)
+
 	hdlr.respondJSON(writer, request,
 		map[string]string{"status": "quit"},
 		http.StatusOK)
@@ -1809,11 +2088,10 @@ func (hdlr *Handlers) handleMode(
 		return
 	}
 
-	_ = bodyLines
-
 	hdlr.handleChannelMode(
 		writer, request,
 		sessionID, clientID, nick, channel,
+		bodyLines,
 	)
 }
 
@@ -1822,6 +2100,7 @@ func (hdlr *Handlers) handleChannelMode(
 	request *http.Request,
 	sessionID, clientID int64,
 	nick, channel string,
+	bodyLines func() []string,
 ) {
 	ctx := request.Context()
 
@@ -1838,10 +2117,47 @@ func (hdlr *Handlers) handleChannelMode(
 		return
 	}
 
+	lines := bodyLines()
+	if len(lines) > 0 {
+		hdlr.applyChannelMode(
+			writer, request,
+			sessionID, clientID, nick,
+			channel, chID, lines,
+		)
+
+		return
+	}
+
+	hdlr.queryChannelMode(
+		writer, request,
+		sessionID, clientID, nick, channel, chID,
+	)
+}
+
+// queryChannelMode sends RPL_CHANNELMODEIS and
+// RPL_CREATIONTIME for a channel. Includes +H if
+// the channel has a hashcash requirement.
+func (hdlr *Handlers) queryChannelMode(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, channel string,
+	chID int64,
+) {
+	ctx := request.Context()
+
+	modeStr := "+n"
+
+	bits, bitsErr := hdlr.params.Database.
+		GetChannelHashcashBits(ctx, chID)
+	if bitsErr == nil && bits > 0 {
+		modeStr = fmt.Sprintf("+nH %d", bits)
+	}
+
 	// 324 RPL_CHANNELMODEIS
 	hdlr.enqueueNumeric(
 		ctx, clientID, irc.RplChannelModeIs, nick,
-		[]string{channel, "+n"}, "",
+		[]string{channel, modeStr}, "",
 	)
 
 	// 329 RPL_CREATIONTIME
@@ -1866,6 +2182,156 @@ func (hdlr *Handlers) handleChannelMode(
 		http.StatusOK)
 }
 
+// applyChannelMode handles setting channel modes.
+// Currently supports +H/-H for hashcash bits.
+func (hdlr *Handlers) applyChannelMode(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, channel string,
+	chID int64,
+	modeArgs []string,
+) {
+	ctx := request.Context()
+	modeStr := modeArgs[0]
+
+	switch modeStr {
+	case "+H":
+		hdlr.setHashcashMode(
+			writer, request,
+			sessionID, clientID, nick,
+			channel, chID, modeArgs,
+		)
+	case "-H":
+		hdlr.clearHashcashMode(
+			writer, request,
+			sessionID, clientID, nick,
+			channel, chID,
+		)
+	default:
+		// Unknown or unsupported mode change.
+		hdlr.enqueueNumeric(
+			ctx, clientID, irc.ErrUnknownMode, nick,
+			[]string{modeStr},
+			"is unknown mode char to me",
+		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
+	}
+}
+
+const (
+	// minHashcashBits is the minimum allowed hashcash
+	// difficulty for channels.
+	minHashcashBits = 1
+	// maxHashcashBits is the maximum allowed hashcash
+	// difficulty for channels.
+	maxHashcashBits = 40
+)
+
+// setHashcashMode handles MODE #channel +H <bits>.
+func (hdlr *Handlers) setHashcashMode(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, channel string,
+	chID int64,
+	modeArgs []string,
+) {
+	ctx := request.Context()
+
+	if len(modeArgs) < 2 { //nolint:mnd // +H requires a bits arg
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNeedMoreParams, nick, []string{irc.CmdMode},
+			"Not enough parameters (+H requires bits)",
+		)
+
+		return
+	}
+
+	bits, err := strconv.Atoi(modeArgs[1])
+	if err != nil || bits < minHashcashBits ||
+		bits > maxHashcashBits {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrUnknownMode, nick, []string{"+H"},
+			fmt.Sprintf(
+				"Invalid hashcash bits (must be %d-%d)",
+				minHashcashBits, maxHashcashBits,
+			),
+		)
+
+		return
+	}
+
+	err = hdlr.params.Database.SetChannelHashcashBits(
+		ctx, chID, bits,
+	)
+	if err != nil {
+		hdlr.log.Error(
+			"set channel hashcash bits", "error", err,
+		)
+		hdlr.respondError(
+			writer, request,
+			"internal error",
+			http.StatusInternalServerError,
+		)
+
+		return
+	}
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplChannelModeIs, nick,
+		[]string{
+			channel,
+			fmt.Sprintf("+H %d", bits),
+		}, "",
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{"status": "ok"},
+		http.StatusOK)
+}
+
+// clearHashcashMode handles MODE #channel -H.
+func (hdlr *Handlers) clearHashcashMode(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, channel string,
+	chID int64,
+) {
+	ctx := request.Context()
+
+	err := hdlr.params.Database.SetChannelHashcashBits(
+		ctx, chID, 0,
+	)
+	if err != nil {
+		hdlr.log.Error(
+			"clear channel hashcash bits", "error", err,
+		)
+		hdlr.respondError(
+			writer, request,
+			"internal error",
+			http.StatusInternalServerError,
+		)
+
+		return
+	}
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, irc.RplChannelModeIs, nick,
+		[]string{channel, "+n"}, "",
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{"status": "ok"},
+		http.StatusOK)
+}
+
 // handleNames sends NAMES reply for a channel.
 func (hdlr *Handlers) handleNames(
 	writer http.ResponseWriter,
@@ -2385,6 +2851,8 @@ func (hdlr *Handlers) HandleLogout() http.HandlerFunc {
 			)
 		}
 
+		hdlr.clearAuthCookie(writer, request)
+
 		hdlr.respondJSON(writer, request,
 			map[string]string{"status": "ok"},
 			http.StatusOK)
@@ -2467,12 +2935,20 @@ func (hdlr *Handlers) HandleServerInfo() http.HandlerFunc {
 			return
 		}
 
-		hdlr.respondJSON(writer, request, map[string]any{
+		resp := map[string]any{
 			"name":    hdlr.params.Config.ServerName,
 			"version": hdlr.params.Globals.Version,
 			"motd":    hdlr.params.Config.MOTD,
 			"users":   users,
-		}, http.StatusOK)
+		}
+
+		if hdlr.params.Config.HashcashBits > 0 {
+			resp["hashcash_bits"] = hdlr.params.Config.HashcashBits
+		}
+
+		hdlr.respondJSON(
+			writer, request, resp, http.StatusOK,
+		)
 	}
 }
 

internal/handlers/auth.go

@@ -5,117 +5,11 @@ import (
 	"net/http"
 	"strings"
 
-	"git.eeqj.de/sneak/neoirc/internal/db"
+	"git.eeqj.de/sneak/neoirc/pkg/irc"
 )
 
 const minPasswordLength = 8
 
-// HandleRegister creates a new user with a password.
-func (hdlr *Handlers) HandleRegister() http.HandlerFunc {
-	return func(
-		writer http.ResponseWriter,
-		request *http.Request,
-	) {
-		request.Body = http.MaxBytesReader(
-			writer, request.Body, hdlr.maxBodySize(),
-		)
-
-		hdlr.handleRegister(writer, request)
-	}
-}
-
-func (hdlr *Handlers) handleRegister(
-	writer http.ResponseWriter,
-	request *http.Request,
-) {
-	type registerRequest struct {
-		Nick     string `json:"nick"`
-		Password string `json:"password"`
-	}
-
-	var payload registerRequest
-
-	err := json.NewDecoder(request.Body).Decode(&payload)
-	if err != nil {
-		hdlr.respondError(
-			writer, request,
-			"invalid request body",
-			http.StatusBadRequest,
-		)
-
-		return
-	}
-
-	payload.Nick = strings.TrimSpace(payload.Nick)
-
-	if !validNickRe.MatchString(payload.Nick) {
-		hdlr.respondError(
-			writer, request,
-			"invalid nick format",
-			http.StatusBadRequest,
-		)
-
-		return
-	}
-
-	if len(payload.Password) < minPasswordLength {
-		hdlr.respondError(
-			writer, request,
-			"password must be at least 8 characters",
-			http.StatusBadRequest,
-		)
-
-		return
-	}
-
-	sessionID, clientID, token, err :=
-		hdlr.params.Database.RegisterUser(
-			request.Context(),
-			payload.Nick,
-			payload.Password,
-		)
-	if err != nil {
-		hdlr.handleRegisterError(
-			writer, request, err,
-		)
-
-		return
-	}
-
-	hdlr.deliverMOTD(request, clientID, sessionID, payload.Nick)
-
-	hdlr.respondJSON(writer, request, map[string]any{
-		"id":    sessionID,
-		"nick":  payload.Nick,
-		"token": token,
-	}, http.StatusCreated)
-}
-
-func (hdlr *Handlers) handleRegisterError(
-	writer http.ResponseWriter,
-	request *http.Request,
-	err error,
-) {
-	if db.IsUniqueConstraintError(err) {
-		hdlr.respondError(
-			writer, request,
-			"nick already taken",
-			http.StatusConflict,
-		)
-
-		return
-	}
-
-	hdlr.log.Error(
-		"register user failed", "error", err,
-	)
-	hdlr.respondError(
-		writer, request,
-		"internal error",
-		http.StatusInternalServerError,
-	)
-}
-
 // HandleLogin authenticates a user with nick and password.
 func (hdlr *Handlers) HandleLogin() http.HandlerFunc {
 	return func(
@@ -180,6 +74,8 @@ func (hdlr *Handlers) handleLogin(
 		return
 	}
 
+	hdlr.stats.IncrConnections()
+
 	hdlr.deliverMOTD(
 		request, clientID, sessionID, payload.Nick,
 	)
@@ -190,9 +86,66 @@ func (hdlr *Handlers) handleLogin(
 		request, clientID, sessionID, payload.Nick,
 	)
 
+	hdlr.setAuthCookie(writer, request, token)
+
 	hdlr.respondJSON(writer, request, map[string]any{
 		"id":   sessionID,
 		"nick": payload.Nick,
-		"token": token,
 	}, http.StatusOK)
 }
+
+// handlePass handles the IRC PASS command to set a
+// password on the authenticated session, enabling
+// multi-client login via POST /api/v1/login.
+func (hdlr *Handlers) handlePass(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick string,
+	bodyLines func() []string,
+) {
+	lines := bodyLines()
+	if len(lines) == 0 || lines[0] == "" {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNeedMoreParams, nick,
+			[]string{irc.CmdPass},
+			"Not enough parameters",
+		)
+
+		return
+	}
+
+	password := lines[0]
+
+	if len(password) < minPasswordLength {
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			irc.ErrNeedMoreParams, nick,
+			[]string{irc.CmdPass},
+			"Password must be at least 8 characters",
+		)
+
+		return
+	}
+
+	err := hdlr.params.Database.SetPassword(
+		request.Context(), sessionID, password,
+	)
+	if err != nil {
+		hdlr.log.Error(
+			"set password failed", "error", err,
+		)
+		hdlr.respondError(
+			writer, request,
+			"internal error",
+			http.StatusInternalServerError,
+		)
+
+		return
+	}
+
+	hdlr.respondJSON(writer, request,
+		map[string]string{"status": "ok"},
+		http.StatusOK)
+}

internal/handlers/handlers.go

@@ -13,8 +13,10 @@ import (
 	"git.eeqj.de/sneak/neoirc/internal/config"
 	"git.eeqj.de/sneak/neoirc/internal/db"
 	"git.eeqj.de/sneak/neoirc/internal/globals"
+	"git.eeqj.de/sneak/neoirc/internal/hashcash"
 	"git.eeqj.de/sneak/neoirc/internal/healthcheck"
 	"git.eeqj.de/sneak/neoirc/internal/logger"
+	"git.eeqj.de/sneak/neoirc/internal/stats"
 	"go.uber.org/fx"
 )
 
@@ -29,16 +31,25 @@ type Params struct {
 	Config      *config.Config
 	Database    *db.Database
 	Healthcheck *healthcheck.Healthcheck
+	Stats       *stats.Tracker
 }
 
 const defaultIdleTimeout = 30 * 24 * time.Hour
 
+// spentHashcashTTL is how long spent hashcash tokens are
+// retained for replay prevention. Per issue requirements,
+// this is 1 year.
+const spentHashcashTTL = 365 * 24 * time.Hour
+
 // Handlers manages HTTP request handling.
 type Handlers struct {
 	params          *Params
 	log             *slog.Logger
 	hc              *healthcheck.Healthcheck
 	broker          *broker.Broker
+	hashcashVal     *hashcash.Validator
+	channelHashcash *hashcash.ChannelValidator
+	stats           *stats.Tracker
 	cancelCleanup   context.CancelFunc
 }
 
@@ -47,11 +58,19 @@ func New(
 	lifecycle fx.Lifecycle,
 	params Params,
 ) (*Handlers, error) {
+	resource := params.Config.ServerName
+	if resource == "" {
+		resource = "neoirc"
+	}
+
 	hdlr := &Handlers{ //nolint:exhaustruct // cancelCleanup set in startCleanup
 		params:          &params,
 		log:             params.Logger.Get(),
 		hc:              params.Healthcheck,
 		broker:          broker.New(),
+		hashcashVal:     hashcash.NewValidator(resource),
+		channelHashcash: hashcash.NewChannelValidator(),
+		stats:           params.Stats,
 	}
 
 	lifecycle.Append(fx.Hook{
@@ -273,4 +292,20 @@ func (hdlr *Handlers) pruneQueuesAndMessages(
 			)
 		}
 	}
+
+	// Prune spent hashcash tokens older than 1 year.
+	hashcashCutoff := time.Now().Add(-spentHashcashTTL)
+
+	pruned, err := hdlr.params.Database.
+		PruneSpentHashcash(ctx, hashcashCutoff)
+	if err != nil {
+		hdlr.log.Error(
+			"spent hashcash pruning failed", "error", err,
+		)
+	} else if pruned > 0 {
+		hdlr.log.Info(
+			"pruned spent hashcash tokens",
+			"deleted", pruned,
+		)
+	}
 }

internal/handlers/healthcheck.go

@@ -12,7 +12,7 @@ func (hdlr *Handlers) HandleHealthCheck() http.HandlerFunc {
 		writer http.ResponseWriter,
 		request *http.Request,
 	) {
-		resp := hdlr.hc.Healthcheck()
+		resp := hdlr.hc.Healthcheck(request.Context())
 		hdlr.respondJSON(writer, request, resp, httpStatusOK)
 	}
 }

internal/hashcash/channel.go

@@ -0,0 +1,186 @@
+package hashcash
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	errBodyHashMismatch = errors.New(
+		"body hash mismatch",
+	)
+	errBodyHashMissing = errors.New(
+		"body hash missing",
+	)
+)
+
+// ChannelValidator checks hashcash stamps for
+// per-channel PRIVMSG validation. It verifies that
+// stamps are bound to a specific channel and message
+// body. Replay prevention is handled externally via
+// the database spent_hashcash table for persistence
+// across server restarts (1-year TTL).
+type ChannelValidator struct{}
+
+// NewChannelValidator creates a ChannelValidator.
+func NewChannelValidator() *ChannelValidator {
+	return &ChannelValidator{}
+}
+
+// BodyHash computes the hex-encoded SHA-256 hash of a
+// message body for use in hashcash stamp validation.
+func BodyHash(body []byte) string {
+	hash := sha256.Sum256(body)
+
+	return hex.EncodeToString(hash[:])
+}
+
+// ValidateStamp checks a channel hashcash stamp. It
+// verifies the stamp format, difficulty, date, channel
+// binding, body hash binding, and proof-of-work. Replay
+// detection is NOT performed here — callers must check
+// the spent_hashcash table separately.
+//
+// Stamp format: 1:bits:YYMMDD:channel:bodyhash:counter.
+func (cv *ChannelValidator) ValidateStamp(
+	stamp string,
+	requiredBits int,
+	channel string,
+	bodyHash string,
+) error {
+	if requiredBits <= 0 {
+		return nil
+	}
+
+	parts := strings.Split(stamp, ":")
+	if len(parts) != stampFields {
+		return fmt.Errorf(
+			"%w: expected %d, got %d",
+			errInvalidFields, stampFields, len(parts),
+		)
+	}
+
+	version := parts[0]
+	bitsStr := parts[1]
+	dateStr := parts[2]
+	resource := parts[3]
+	stampBodyHash := parts[4]
+
+	headerErr := validateChannelHeader(
+		version, bitsStr, resource,
+		requiredBits, channel,
+	)
+	if headerErr != nil {
+		return headerErr
+	}
+
+	stampTime, parseErr := parseStampDate(dateStr)
+	if parseErr != nil {
+		return parseErr
+	}
+
+	timeErr := validateTime(stampTime)
+	if timeErr != nil {
+		return timeErr
+	}
+
+	bodyErr := validateBodyHash(
+		stampBodyHash, bodyHash,
+	)
+	if bodyErr != nil {
+		return bodyErr
+	}
+
+	return validateProof(stamp, requiredBits)
+}
+
+// StampHash returns a deterministic hash of a stamp
+// string for use as a spent-token key.
+func StampHash(stamp string) string {
+	hash := sha256.Sum256([]byte(stamp))
+
+	return hex.EncodeToString(hash[:])
+}
+
+func validateChannelHeader(
+	version, bitsStr, resource string,
+	requiredBits int,
+	channel string,
+) error {
+	if version != stampVersion {
+		return fmt.Errorf(
+			"%w: %s", errBadVersion, version,
+		)
+	}
+
+	claimedBits, err := strconv.Atoi(bitsStr)
+	if err != nil || claimedBits < requiredBits {
+		return fmt.Errorf(
+			"%w: need %d bits",
+			errInsufficientBits, requiredBits,
+		)
+	}
+
+	if resource != channel {
+		return fmt.Errorf(
+			"%w: got %q, want %q",
+			errWrongResource, resource, channel,
+		)
+	}
+
+	return nil
+}
+
+func validateBodyHash(
+	stampBodyHash, expectedBodyHash string,
+) error {
+	if stampBodyHash == "" {
+		return errBodyHashMissing
+	}
+
+	if stampBodyHash != expectedBodyHash {
+		return fmt.Errorf(
+			"%w: got %q, want %q",
+			errBodyHashMismatch,
+			stampBodyHash, expectedBodyHash,
+		)
+	}
+
+	return nil
+}
+
+// MintChannelStamp computes a channel hashcash stamp
+// with the given difficulty, channel name, and body hash.
+// This is intended for clients to generate stamps before
+// sending PRIVMSG to hashcash-protected channels.
+//
+// Stamp format: 1:bits:YYMMDD:channel:bodyhash:counter.
+func MintChannelStamp(
+	bits int,
+	channel string,
+	bodyHash string,
+) string {
+	date := time.Now().UTC().Format(dateFormatShort)
+	prefix := fmt.Sprintf(
+		"1:%d:%s:%s:%s:",
+		bits, date, channel, bodyHash,
+	)
+
+	counter := uint64(0)
+
+	for {
+		stamp := prefix + strconv.FormatUint(counter, 16)
+		hash := sha256.Sum256([]byte(stamp))
+
+		if hasLeadingZeroBits(hash[:], bits) {
+			return stamp
+		}
+
+		counter++
+	}
+}

internal/hashcash/channel_test.go

@@ -0,0 +1,244 @@
+package hashcash_test
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"testing"
+
+	"git.eeqj.de/sneak/neoirc/internal/hashcash"
+)
+
+const (
+	testChannel  = "#general"
+	testBodyText = `["hello world"]`
+)
+
+func testBodyHash() string {
+	hash := sha256.Sum256([]byte(testBodyText))
+
+	return hex.EncodeToString(hash[:])
+}
+
+func TestChannelValidateHappyPath(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	stamp := hashcash.MintChannelStamp(
+		testBits, testChannel, bodyHash,
+	)
+
+	err := validator.ValidateStamp(
+		stamp, testBits, testChannel, bodyHash,
+	)
+	if err != nil {
+		t.Fatalf("valid channel stamp rejected: %v", err)
+	}
+}
+
+func TestChannelValidateWrongChannel(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	stamp := hashcash.MintChannelStamp(
+		testBits, testChannel, bodyHash,
+	)
+
+	err := validator.ValidateStamp(
+		stamp, testBits, "#other", bodyHash,
+	)
+	if err == nil {
+		t.Fatal("expected channel mismatch error")
+	}
+}
+
+func TestChannelValidateWrongBodyHash(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	stamp := hashcash.MintChannelStamp(
+		testBits, testChannel, bodyHash,
+	)
+
+	wrongHash := sha256.Sum256([]byte("different body"))
+	wrongBodyHash := hex.EncodeToString(wrongHash[:])
+
+	err := validator.ValidateStamp(
+		stamp, testBits, testChannel, wrongBodyHash,
+	)
+	if err == nil {
+		t.Fatal("expected body hash mismatch error")
+	}
+}
+
+func TestChannelValidateInsufficientBits(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	// Mint with 2 bits but require 4.
+	stamp := hashcash.MintChannelStamp(
+		testBits, testChannel, bodyHash,
+	)
+
+	err := validator.ValidateStamp(
+		stamp, 4, testChannel, bodyHash,
+	)
+	if err == nil {
+		t.Fatal("expected insufficient bits error")
+	}
+}
+
+func TestChannelValidateZeroBitsSkips(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+
+	err := validator.ValidateStamp(
+		"garbage", 0, "#ch", "abc",
+	)
+	if err != nil {
+		t.Fatalf("zero bits should skip: %v", err)
+	}
+}
+
+func TestChannelValidateBadFormat(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+
+	err := validator.ValidateStamp(
+		"not:valid", testBits, testChannel, "abc",
+	)
+	if err == nil {
+		t.Fatal("expected bad format error")
+	}
+}
+
+func TestChannelValidateBadVersion(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	stamp := "2:2:260317:#general:" + bodyHash + ":counter"
+
+	err := validator.ValidateStamp(
+		stamp, testBits, testChannel, bodyHash,
+	)
+	if err == nil {
+		t.Fatal("expected bad version error")
+	}
+}
+
+func TestChannelValidateExpiredStamp(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	// Mint with a very old date by manually constructing.
+	stamp := mintStampWithDate(
+		t, testBits, testChannel, "200101",
+	)
+
+	err := validator.ValidateStamp(
+		stamp, testBits, testChannel, bodyHash,
+	)
+	if err == nil {
+		t.Fatal("expected expired stamp error")
+	}
+}
+
+func TestChannelValidateMissingBodyHash(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewChannelValidator()
+	bodyHash := testBodyHash()
+
+	// Construct a stamp with empty body hash field.
+	stamp := mintStampWithDate(
+		t, testBits, testChannel, todayDate(),
+	)
+
+	// This uses the session-style stamp which has empty
+	// ext field — body hash is missing.
+	err := validator.ValidateStamp(
+		stamp, testBits, testChannel, bodyHash,
+	)
+	if err == nil {
+		t.Fatal("expected missing body hash error")
+	}
+}
+
+func TestBodyHash(t *testing.T) {
+	t.Parallel()
+
+	body := []byte(`["hello world"]`)
+	bodyHash := hashcash.BodyHash(body)
+
+	if len(bodyHash) != 64 {
+		t.Fatalf(
+			"expected 64-char hex hash, got %d",
+			len(bodyHash),
+		)
+	}
+
+	// Same input should produce same hash.
+	bodyHash2 := hashcash.BodyHash(body)
+	if bodyHash != bodyHash2 {
+		t.Fatal("body hash not deterministic")
+	}
+
+	// Different input should produce different hash.
+	bodyHash3 := hashcash.BodyHash([]byte("different"))
+	if bodyHash == bodyHash3 {
+		t.Fatal("different inputs produced same hash")
+	}
+}
+
+func TestStampHash(t *testing.T) {
+	t.Parallel()
+
+	hash1 := hashcash.StampHash("stamp1")
+	hash2 := hashcash.StampHash("stamp2")
+
+	if hash1 == hash2 {
+		t.Fatal("different stamps produced same hash")
+	}
+
+	// Same input should be deterministic.
+	hash1b := hashcash.StampHash("stamp1")
+	if hash1 != hash1b {
+		t.Fatal("stamp hash not deterministic")
+	}
+}
+
+func TestMintChannelStamp(t *testing.T) {
+	t.Parallel()
+
+	bodyHash := testBodyHash()
+	stamp := hashcash.MintChannelStamp(
+		testBits, testChannel, bodyHash,
+	)
+
+	if stamp == "" {
+		t.Fatal("expected non-empty stamp")
+	}
+
+	// Validate the minted stamp.
+	validator := hashcash.NewChannelValidator()
+
+	err := validator.ValidateStamp(
+		stamp, testBits, testChannel, bodyHash,
+	)
+	if err != nil {
+		t.Fatalf("minted stamp failed validation: %v", err)
+	}
+}

internal/hashcash/hashcash.go

@@ -0,0 +1,277 @@
+// Package hashcash implements SHA-256-based hashcash
+// proof-of-work validation for abuse prevention.
+//
+// Stamp format: 1:bits:YYMMDD:resource::counter.
+//
+// The SHA-256 hash of the entire stamp string must have
+// at least `bits` leading zero bits.
+package hashcash
+
+import (
+	"crypto/sha256"
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	// stampVersion is the only supported hashcash version.
+	stampVersion = "1"
+	// stampFields is the number of fields in a stamp.
+	stampFields = 6
+	// maxStampAge is how old a stamp can be before
+	// rejection.
+	maxStampAge = 48 * time.Hour
+	// maxFutureSkew allows stamps slightly in the future.
+	maxFutureSkew = 1 * time.Hour
+	// pruneInterval controls how often expired stamps are
+	// removed from the spent set.
+	pruneInterval = 10 * time.Minute
+	// dateFormatShort is the YYMMDD date layout.
+	dateFormatShort = "060102"
+	// dateFormatLong is the YYMMDDHHMMSS date layout.
+	dateFormatLong = "060102150405"
+	// dateShortLen is the length of YYMMDD.
+	dateShortLen = 6
+	// dateLongLen is the length of YYMMDDHHMMSS.
+	dateLongLen = 12
+	// bitsPerByte is the number of bits in a byte.
+	bitsPerByte = 8
+	// fullByteMask is 0xFF, a mask for all bits in a byte.
+	fullByteMask = 0xFF
+)
+
+var (
+	errInvalidFields    = errors.New("invalid stamp field count")
+	errBadVersion       = errors.New("unsupported stamp version")
+	errInsufficientBits = errors.New("insufficient difficulty")
+	errWrongResource    = errors.New("wrong resource")
+	errStampExpired     = errors.New("stamp expired")
+	errStampFuture      = errors.New("stamp date in future")
+	errProofFailed      = errors.New("proof-of-work failed")
+	errStampReused      = errors.New("stamp already used")
+	errBadDateFormat    = errors.New("unrecognized date format")
+)
+
+// Validator checks hashcash stamps for validity and
+// prevents replay attacks via an in-memory spent set.
+type Validator struct {
+	resource string
+	mu       sync.Mutex
+	spent    map[string]time.Time
+}
+
+// NewValidator creates a Validator for the given resource.
+func NewValidator(resource string) *Validator {
+	validator := &Validator{
+		resource: resource,
+		mu:       sync.Mutex{},
+		spent:    make(map[string]time.Time),
+	}
+
+	go validator.pruneLoop()
+
+	return validator
+}
+
+// Validate checks a hashcash stamp. It returns nil if the
+// stamp is valid and has not been seen before.
+func (v *Validator) Validate(
+	stamp string,
+	requiredBits int,
+) error {
+	if requiredBits <= 0 {
+		return nil
+	}
+
+	parts := strings.Split(stamp, ":")
+	if len(parts) != stampFields {
+		return fmt.Errorf(
+			"%w: expected %d, got %d",
+			errInvalidFields, stampFields, len(parts),
+		)
+	}
+
+	version := parts[0]
+	bitsStr := parts[1]
+	dateStr := parts[2]
+	resource := parts[3]
+
+	if err := v.validateHeader(
+		version, bitsStr, resource, requiredBits,
+	); err != nil {
+		return err
+	}
+
+	stampTime, err := parseStampDate(dateStr)
+	if err != nil {
+		return err
+	}
+
+	if err := validateTime(stampTime); err != nil {
+		return err
+	}
+
+	if err := validateProof(
+		stamp, requiredBits,
+	); err != nil {
+		return err
+	}
+
+	return v.checkAndRecordStamp(stamp, stampTime)
+}
+
+func (v *Validator) validateHeader(
+	version, bitsStr, resource string,
+	requiredBits int,
+) error {
+	if version != stampVersion {
+		return fmt.Errorf(
+			"%w: %s", errBadVersion, version,
+		)
+	}
+
+	claimedBits, err := strconv.Atoi(bitsStr)
+	if err != nil || claimedBits < requiredBits {
+		return fmt.Errorf(
+			"%w: need %d bits",
+			errInsufficientBits, requiredBits,
+		)
+	}
+
+	if resource != v.resource {
+		return fmt.Errorf(
+			"%w: got %q, want %q",
+			errWrongResource, resource, v.resource,
+		)
+	}
+
+	return nil
+}
+
+func validateTime(stampTime time.Time) error {
+	now := time.Now()
+
+	if now.Sub(stampTime) > maxStampAge {
+		return errStampExpired
+	}
+
+	if stampTime.Sub(now) > maxFutureSkew {
+		return errStampFuture
+	}
+
+	return nil
+}
+
+func validateProof(stamp string, requiredBits int) error {
+	hash := sha256.Sum256([]byte(stamp))
+	if !hasLeadingZeroBits(hash[:], requiredBits) {
+		return fmt.Errorf(
+			"%w: need %d leading zero bits",
+			errProofFailed, requiredBits,
+		)
+	}
+
+	return nil
+}
+
+func (v *Validator) checkAndRecordStamp(
+	stamp string,
+	stampTime time.Time,
+) error {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+
+	if _, ok := v.spent[stamp]; ok {
+		return errStampReused
+	}
+
+	v.spent[stamp] = stampTime
+
+	return nil
+}
+
+// hasLeadingZeroBits checks if the hash has at least n
+// leading zero bits.
+func hasLeadingZeroBits(hash []byte, numBits int) bool {
+	fullBytes := numBits / bitsPerByte
+	remainBits := numBits % bitsPerByte
+
+	for idx := range fullBytes {
+		if hash[idx] != 0 {
+			return false
+		}
+	}
+
+	if remainBits > 0 && fullBytes < len(hash) {
+		mask := byte(
+			fullByteMask << (bitsPerByte - remainBits),
+		)
+
+		if hash[fullBytes]&mask != 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
+// parseStampDate parses a hashcash date stamp.
+// Supports YYMMDD and YYMMDDHHMMSS formats.
+func parseStampDate(dateStr string) (time.Time, error) {
+	switch len(dateStr) {
+	case dateShortLen:
+		parsed, err := time.Parse(
+			dateFormatShort, dateStr,
+		)
+		if err != nil {
+			return time.Time{}, fmt.Errorf(
+				"parse date: %w", err,
+			)
+		}
+
+		return parsed, nil
+	case dateLongLen:
+		parsed, err := time.Parse(
+			dateFormatLong, dateStr,
+		)
+		if err != nil {
+			return time.Time{}, fmt.Errorf(
+				"parse date: %w", err,
+			)
+		}
+
+		return parsed, nil
+	default:
+		return time.Time{}, fmt.Errorf(
+			"%w: %q", errBadDateFormat, dateStr,
+		)
+	}
+}
+
+// pruneLoop periodically removes expired stamps from the
+// spent set.
+func (v *Validator) pruneLoop() {
+	ticker := time.NewTicker(pruneInterval)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		v.prune()
+	}
+}
+
+func (v *Validator) prune() {
+	cutoff := time.Now().Add(-maxStampAge)
+
+	v.mu.Lock()
+	defer v.mu.Unlock()
+
+	for stamp, stampTime := range v.spent {
+		if stampTime.Before(cutoff) {
+			delete(v.spent, stamp)
+		}
+	}
+}

internal/hashcash/hashcash_test.go

@@ -0,0 +1,261 @@
+package hashcash_test
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"testing"
+	"time"
+
+	"git.eeqj.de/sneak/neoirc/internal/hashcash"
+)
+
+const testBits = 2
+
+// mintStampWithDate creates a valid hashcash stamp using
+// the given date string.
+func mintStampWithDate(
+	tb testing.TB,
+	bits int,
+	resource string,
+	date string,
+) string {
+	tb.Helper()
+
+	prefix := fmt.Sprintf(
+		"1:%d:%s:%s::", bits, date, resource,
+	)
+
+	for {
+		counterVal, err := rand.Int(
+			rand.Reader, big.NewInt(1<<48),
+		)
+		if err != nil {
+			tb.Fatalf("random counter: %v", err)
+		}
+
+		stamp := prefix + hex.EncodeToString(
+			counterVal.Bytes(),
+		)
+		hash := sha256.Sum256([]byte(stamp))
+
+		if hasLeadingZeroBits(hash[:], bits) {
+			return stamp
+		}
+	}
+}
+
+// hasLeadingZeroBits checks if hash has at least numBits
+// leading zero bits. Duplicated here for test minting.
+func hasLeadingZeroBits(
+	hash []byte,
+	numBits int,
+) bool {
+	fullBytes := numBits / 8
+	remainBits := numBits % 8
+
+	for idx := range fullBytes {
+		if hash[idx] != 0 {
+			return false
+		}
+	}
+
+	if remainBits > 0 && fullBytes < len(hash) {
+		mask := byte(0xFF << (8 - remainBits))
+
+		if hash[fullBytes]&mask != 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
+func todayDate() string {
+	return time.Now().UTC().Format("060102")
+}
+
+func TestMintAndValidate(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	stamp := mintStampWithDate(
+		t, testBits, "test-resource", todayDate(),
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err != nil {
+		t.Fatalf("valid stamp rejected: %v", err)
+	}
+}
+
+func TestReplayDetection(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	stamp := mintStampWithDate(
+		t, testBits, "test-resource", todayDate(),
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err != nil {
+		t.Fatalf("first use failed: %v", err)
+	}
+
+	err = validator.Validate(stamp, testBits)
+	if err == nil {
+		t.Fatal("replay not detected")
+	}
+}
+
+func TestResourceMismatch(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("correct-resource")
+	stamp := mintStampWithDate(
+		t, testBits, "wrong-resource", todayDate(),
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err == nil {
+		t.Fatal("expected resource mismatch error")
+	}
+}
+
+func TestInvalidStampFormat(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+
+	err := validator.Validate(
+		"not:a:valid:stamp", testBits,
+	)
+	if err == nil {
+		t.Fatal("expected error for bad format")
+	}
+}
+
+func TestBadVersion(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	stamp := fmt.Sprintf(
+		"2:%d:%s:%s::abc123",
+		testBits, todayDate(), "test-resource",
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err == nil {
+		t.Fatal("expected bad version error")
+	}
+}
+
+func TestInsufficientDifficulty(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	// Claimed bits=1, but we require testBits=2.
+	stamp := fmt.Sprintf(
+		"1:1:%s:%s::counter",
+		todayDate(), "test-resource",
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err == nil {
+		t.Fatal("expected insufficient bits error")
+	}
+}
+
+func TestExpiredStamp(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	oldDate := time.Now().Add(-72 * time.Hour).
+		UTC().Format("060102")
+	stamp := mintStampWithDate(
+		t, testBits, "test-resource", oldDate,
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err == nil {
+		t.Fatal("expected expired stamp error")
+	}
+}
+
+func TestZeroBitsSkipsValidation(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+
+	err := validator.Validate("garbage", 0)
+	if err != nil {
+		t.Fatalf("zero bits should skip: %v", err)
+	}
+}
+
+func TestLongDateFormat(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	longDate := time.Now().UTC().Format("060102150405")
+	stamp := mintStampWithDate(
+		t, testBits, "test-resource", longDate,
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err != nil {
+		t.Fatalf("long date stamp rejected: %v", err)
+	}
+}
+
+func TestBadDateFormat(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+	stamp := fmt.Sprintf(
+		"1:%d:BADDATE:%s::counter",
+		testBits, "test-resource",
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err == nil {
+		t.Fatal("expected bad date error")
+	}
+}
+
+func TestMultipleUniqueStamps(t *testing.T) {
+	t.Parallel()
+
+	validator := hashcash.NewValidator("test-resource")
+
+	for range 5 {
+		stamp := mintStampWithDate(
+			t, testBits, "test-resource", todayDate(),
+		)
+
+		err := validator.Validate(stamp, testBits)
+		if err != nil {
+			t.Fatalf("unique stamp rejected: %v", err)
+		}
+	}
+}
+
+func TestHigherBitsStillValid(t *testing.T) {
+	t.Parallel()
+
+	// Mint with bits=4 but validate requiring only 2.
+	validator := hashcash.NewValidator("test-resource")
+	stamp := mintStampWithDate(
+		t, 4, "test-resource", todayDate(),
+	)
+
+	err := validator.Validate(stamp, testBits)
+	if err != nil {
+		t.Fatalf(
+			"higher-difficulty stamp rejected: %v",
+			err,
+		)
+	}
+}

internal/healthcheck/healthcheck.go

@@ -10,6 +10,7 @@ import (
 	"git.eeqj.de/sneak/neoirc/internal/db"
 	"git.eeqj.de/sneak/neoirc/internal/globals"
 	"git.eeqj.de/sneak/neoirc/internal/logger"
+	"git.eeqj.de/sneak/neoirc/internal/stats"
 	"go.uber.org/fx"
 )
 
@@ -21,6 +22,7 @@ type Params struct {
 	Config   *config.Config
 	Logger   *logger.Logger
 	Database *db.Database
+	Stats    *stats.Tracker
 }
 
 // Healthcheck tracks server uptime and provides health status.
@@ -64,11 +66,22 @@ type Response struct {
 	Version       string `json:"version"`
 	Appname       string `json:"appname"`
 	Maintenance   bool   `json:"maintenanceMode"`
+
+	// Runtime statistics.
+	Sessions             int64 `json:"sessions"`
+	Clients              int64 `json:"clients"`
+	QueuedLines          int64 `json:"queuedLines"`
+	Channels             int64 `json:"channels"`
+	ConnectionsSinceBoot int64 `json:"connectionsSinceBoot"`
+	SessionsSinceBoot    int64 `json:"sessionsSinceBoot"`
+	MessagesSinceBoot    int64 `json:"messagesSinceBoot"`
 }
 
 // Healthcheck returns the current health status of the server.
-func (hcheck *Healthcheck) Healthcheck() *Response {
+func (hcheck *Healthcheck) Healthcheck(
-	return &Response{
+	ctx context.Context,
+) *Response {
+	resp := &Response{
 		Status:        "ok",
 		Now:           time.Now().UTC().Format(time.RFC3339Nano),
 		UptimeSeconds: int64(hcheck.uptime().Seconds()),
@@ -76,6 +89,64 @@ func (hcheck *Healthcheck) Healthcheck() *Response {
 		Appname:       hcheck.params.Globals.Appname,
 		Version:       hcheck.params.Globals.Version,
 		Maintenance:   hcheck.params.Config.MaintenanceMode,
+
+		Sessions:             0,
+		Clients:              0,
+		QueuedLines:          0,
+		Channels:             0,
+		ConnectionsSinceBoot: hcheck.params.Stats.ConnectionsSinceBoot(),
+		SessionsSinceBoot:    hcheck.params.Stats.SessionsSinceBoot(),
+		MessagesSinceBoot:    hcheck.params.Stats.MessagesSinceBoot(),
+	}
+
+	hcheck.populateDBStats(ctx, resp)
+
+	return resp
+}
+
+// populateDBStats fills in database-derived counters.
+func (hcheck *Healthcheck) populateDBStats(
+	ctx context.Context,
+	resp *Response,
+) {
+	sessions, err := hcheck.params.Database.GetUserCount(ctx)
+	if err != nil {
+		hcheck.log.Error(
+			"healthcheck: session count failed",
+			"error", err,
+		)
+	} else {
+		resp.Sessions = sessions
+	}
+
+	clients, err := hcheck.params.Database.GetClientCount(ctx)
+	if err != nil {
+		hcheck.log.Error(
+			"healthcheck: client count failed",
+			"error", err,
+		)
+	} else {
+		resp.Clients = clients
+	}
+
+	queued, err := hcheck.params.Database.GetQueueEntryCount(ctx)
+	if err != nil {
+		hcheck.log.Error(
+			"healthcheck: queue entry count failed",
+			"error", err,
+		)
+	} else {
+		resp.QueuedLines = queued
+	}
+
+	channels, err := hcheck.params.Database.GetChannelCount(ctx)
+	if err != nil {
+		hcheck.log.Error(
+			"healthcheck: channel count failed",
+			"error", err,
+		)
+	} else {
+		resp.Channels = channels
 	}
 }
 

internal/irc/numerics.go

@@ -1,150 +0,0 @@
-// Package irc provides constants and utilities for the
-// IRC protocol, including numeric reply codes from
-// RFC 1459 and RFC 2812, and standard command names.
-package irc
-
-// Connection registration replies (001-005).
-const (
-	RplWelcome  = 1
-	RplYourHost = 2
-	RplCreated  = 3
-	RplMyInfo   = 4
-	RplIsupport = 5
-)
-
-// Command responses (200-399).
-const (
-	RplUmodeIs       = 221
-	RplLuserClient   = 251
-	RplLuserOp       = 252
-	RplLuserUnknown  = 253
-	RplLuserChannels = 254
-	RplLuserMe       = 255
-	RplAway          = 301
-	RplUserHost      = 302
-	RplIson          = 303
-	RplUnaway        = 305
-	RplNowAway       = 306
-	RplWhoisUser     = 311
-	RplWhoisServer   = 312
-	RplWhoisOperator = 313
-	RplEndOfWho      = 315
-	RplWhoisIdle     = 317
-	RplEndOfWhois    = 318
-	RplWhoisChannels = 319
-	RplList          = 322
-	RplListEnd       = 323
-	RplChannelModeIs = 324
-	RplCreationTime  = 329
-	RplNoTopic       = 331
-	RplTopic         = 332
-	RplTopicWhoTime  = 333
-	RplInviting      = 341
-	RplWhoReply      = 352
-	RplNamReply      = 353
-	RplEndOfNames    = 366
-	RplBanList       = 367
-	RplEndOfBanList  = 368
-	RplMotd          = 372
-	RplMotdStart     = 375
-	RplEndOfMotd     = 376
-)
-
-// Error replies (400-599).
-const (
-	ErrNoSuchNick        = 401
-	ErrNoSuchServer      = 402
-	ErrNoSuchChannel     = 403
-	ErrCannotSendToChan  = 404
-	ErrTooManyChannels   = 405
-	ErrNoRecipient       = 411
-	ErrNoTextToSend      = 412
-	ErrUnknownCommand    = 421
-	ErrNoNicknameGiven   = 431
-	ErrErroneusNickname  = 432
-	ErrNicknameInUse     = 433
-	ErrUserNotInChannel  = 441
-	ErrNotOnChannel      = 442
-	ErrNotRegistered     = 451
-	ErrNeedMoreParams    = 461
-	ErrAlreadyRegistered = 462
-	ErrChannelIsFull     = 471
-	ErrInviteOnlyChan    = 473
-	ErrBannedFromChan    = 474
-	ErrBadChannelKey     = 475
-	ErrChanOpPrivsNeeded = 482
-)
-
-// names maps numeric codes to their standard IRC names.
-//
-//nolint:gochecknoglobals
-var names = map[int]string{
-	RplWelcome:       "RPL_WELCOME",
-	RplYourHost:      "RPL_YOURHOST",
-	RplCreated:       "RPL_CREATED",
-	RplMyInfo:        "RPL_MYINFO",
-	RplIsupport:      "RPL_ISUPPORT",
-	RplUmodeIs:       "RPL_UMODEIS",
-	RplLuserClient:   "RPL_LUSERCLIENT",
-	RplLuserOp:       "RPL_LUSEROP",
-	RplLuserUnknown:  "RPL_LUSERUNKNOWN",
-	RplLuserChannels: "RPL_LUSERCHANNELS",
-	RplLuserMe:       "RPL_LUSERME",
-	RplAway:          "RPL_AWAY",
-	RplUserHost:      "RPL_USERHOST",
-	RplIson:          "RPL_ISON",
-	RplUnaway:        "RPL_UNAWAY",
-	RplNowAway:       "RPL_NOWAWAY",
-	RplWhoisUser:     "RPL_WHOISUSER",
-	RplWhoisServer:   "RPL_WHOISSERVER",
-	RplWhoisOperator: "RPL_WHOISOPERATOR",
-	RplEndOfWho:      "RPL_ENDOFWHO",
-	RplWhoisIdle:     "RPL_WHOISIDLE",
-	RplEndOfWhois:    "RPL_ENDOFWHOIS",
-	RplWhoisChannels: "RPL_WHOISCHANNELS",
-	RplList:          "RPL_LIST",
-	RplListEnd:       "RPL_LISTEND", //nolint:misspell
-	RplChannelModeIs: "RPL_CHANNELMODEIS",
-	RplCreationTime:  "RPL_CREATIONTIME",
-	RplNoTopic:       "RPL_NOTOPIC",
-	RplTopic:         "RPL_TOPIC",
-	RplTopicWhoTime:  "RPL_TOPICWHOTIME",
-	RplInviting:      "RPL_INVITING",
-	RplWhoReply:      "RPL_WHOREPLY",
-	RplNamReply:      "RPL_NAMREPLY",
-	RplEndOfNames:    "RPL_ENDOFNAMES",
-	RplBanList:       "RPL_BANLIST",
-	RplEndOfBanList:  "RPL_ENDOFBANLIST",
-	RplMotd:          "RPL_MOTD",
-	RplMotdStart:     "RPL_MOTDSTART",
-	RplEndOfMotd:     "RPL_ENDOFMOTD",
-
-	ErrNoSuchNick:        "ERR_NOSUCHNICK",
-	ErrNoSuchServer:      "ERR_NOSUCHSERVER",
-	ErrNoSuchChannel:     "ERR_NOSUCHCHANNEL",
-	ErrCannotSendToChan:  "ERR_CANNOTSENDTOCHAN",
-	ErrTooManyChannels:   "ERR_TOOMANYCHANNELS",
-	ErrNoRecipient:       "ERR_NORECIPIENT",
-	ErrNoTextToSend:      "ERR_NOTEXTTOSEND",
-	ErrUnknownCommand:    "ERR_UNKNOWNCOMMAND",
-	ErrNoNicknameGiven:   "ERR_NONICKNAMEGIVEN",
-	ErrErroneusNickname:  "ERR_ERRONEUSNICKNAME",
-	ErrNicknameInUse:     "ERR_NICKNAMEINUSE",
-	ErrUserNotInChannel:  "ERR_USERNOTINCHANNEL",
-	ErrNotOnChannel:      "ERR_NOTONCHANNEL",
-	ErrNotRegistered:     "ERR_NOTREGISTERED",
-	ErrNeedMoreParams:    "ERR_NEEDMOREPARAMS",
-	ErrAlreadyRegistered: "ERR_ALREADYREGISTERED",
-	ErrChannelIsFull:     "ERR_CHANNELISFULL",
-	ErrInviteOnlyChan:    "ERR_INVITEONLYCHAN",
-	ErrBannedFromChan:    "ERR_BANNEDFROMCHAN",
-	ErrBadChannelKey:     "ERR_BADCHANNELKEY",
-	ErrChanOpPrivsNeeded: "ERR_CHANOPRIVSNEEDED",
-}
-
-// Name returns the standard IRC name for a numeric code
-// (e.g., Name(2) returns "RPL_YOURHOST"). Returns an
-// empty string if the code is unknown.
-func Name(code int) string {
-	return names[code]
-}

internal/middleware/middleware.go

@@ -11,7 +11,7 @@ import (
 	"git.eeqj.de/sneak/neoirc/internal/globals"
 	"git.eeqj.de/sneak/neoirc/internal/logger"
 	basicauth "github.com/99designs/basicauth-go"
-	chimw "github.com/go-chi/chi/middleware"
+	chimw "github.com/go-chi/chi/v5/middleware"
 	"github.com/go-chi/cors"
 	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
 	ghmm "github.com/slok/go-http-metrics/middleware"
@@ -126,18 +126,23 @@ func (mware *Middleware) Logging() func(http.Handler) http.Handler {
 }
 
 // CORS returns middleware that handles Cross-Origin Resource Sharing.
+// AllowCredentials is true so browsers include cookies in
+// cross-origin API requests.
 func (mware *Middleware) CORS() func(http.Handler) http.Handler {
 	return cors.Handler(cors.Options{ //nolint:exhaustruct // optional fields
-		AllowedOrigins: []string{"*"},
+		AllowOriginFunc: func(
+			_ *http.Request, _ string,
+		) bool {
+			return true
+		},
 		AllowedMethods: []string{
 			"GET", "POST", "PUT", "DELETE", "OPTIONS",
 		},
 		AllowedHeaders: []string{
-			"Accept", "Authorization",
+			"Accept", "Content-Type", "X-CSRF-Token",
-			"Content-Type", "X-CSRF-Token",
 		},
 		ExposedHeaders:   []string{"Link"},
-		AllowCredentials: false,
+		AllowCredentials: true,
 		MaxAge:           corsMaxAge,
 	})
 }

internal/server/routes.go

@@ -8,8 +8,8 @@ import (
 	"git.eeqj.de/sneak/neoirc/web"
 
 	sentryhttp "github.com/getsentry/sentry-go/http"
-	"github.com/go-chi/chi"
+	"github.com/go-chi/chi/v5"
-	"github.com/go-chi/chi/middleware"
+	"github.com/go-chi/chi/v5/middleware"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/viper"
 )
@@ -75,10 +75,6 @@ func (srv *Server) setupAPIv1(router chi.Router) {
 		"/session",
 		srv.handlers.HandleCreateSession(),
 	)
-	router.Post(
-		"/register",
-		srv.handlers.HandleRegister(),
-	)
 	router.Post(
 		"/login",
 		srv.handlers.HandleLogin(),

internal/server/server.go

@@ -20,7 +20,7 @@ import (
 	"go.uber.org/fx"
 
 	"github.com/getsentry/sentry-go"
-	"github.com/go-chi/chi"
+	"github.com/go-chi/chi/v5"
 
 	_ "github.com/joho/godotenv/autoload" // loads .env file
 )

internal/stats/stats.go

@@ -0,0 +1,52 @@
+// Package stats tracks runtime statistics since server boot.
+package stats
+
+import (
+	"sync/atomic"
+)
+
+// Tracker holds atomic counters for runtime statistics
+// that accumulate since the server started.
+type Tracker struct {
+	connectionsSinceBoot atomic.Int64
+	sessionsSinceBoot    atomic.Int64
+	messagesSinceBoot    atomic.Int64
+}
+
+// New creates a new Tracker with all counters at zero.
+func New() *Tracker {
+	return &Tracker{} //nolint:exhaustruct // atomic fields have zero-value defaults
+}
+
+// IncrConnections increments the total connection count.
+func (t *Tracker) IncrConnections() {
+	t.connectionsSinceBoot.Add(1)
+}
+
+// IncrSessions increments the total session count.
+func (t *Tracker) IncrSessions() {
+	t.sessionsSinceBoot.Add(1)
+}
+
+// IncrMessages increments the total PRIVMSG/NOTICE count.
+func (t *Tracker) IncrMessages() {
+	t.messagesSinceBoot.Add(1)
+}
+
+// ConnectionsSinceBoot returns the total number of
+// client connections since boot.
+func (t *Tracker) ConnectionsSinceBoot() int64 {
+	return t.connectionsSinceBoot.Load()
+}
+
+// SessionsSinceBoot returns the total number of sessions
+// created since boot.
+func (t *Tracker) SessionsSinceBoot() int64 {
+	return t.sessionsSinceBoot.Load()
+}
+
+// MessagesSinceBoot returns the total number of
+// PRIVMSG/NOTICE messages sent since boot.
+func (t *Tracker) MessagesSinceBoot() int64 {
+	return t.messagesSinceBoot.Load()
+}

internal/stats/stats_test.go

@@ -0,0 +1,117 @@
+package stats_test
+
+import (
+	"testing"
+
+	"git.eeqj.de/sneak/neoirc/internal/stats"
+)
+
+func TestNew(t *testing.T) {
+	t.Parallel()
+
+	tracker := stats.New()
+	if tracker == nil {
+		t.Fatal("expected non-nil tracker")
+	}
+
+	if tracker.ConnectionsSinceBoot() != 0 {
+		t.Errorf(
+			"expected 0 connections, got %d",
+			tracker.ConnectionsSinceBoot(),
+		)
+	}
+
+	if tracker.SessionsSinceBoot() != 0 {
+		t.Errorf(
+			"expected 0 sessions, got %d",
+			tracker.SessionsSinceBoot(),
+		)
+	}
+
+	if tracker.MessagesSinceBoot() != 0 {
+		t.Errorf(
+			"expected 0 messages, got %d",
+			tracker.MessagesSinceBoot(),
+		)
+	}
+}
+
+func TestIncrConnections(t *testing.T) {
+	t.Parallel()
+
+	tracker := stats.New()
+
+	tracker.IncrConnections()
+	tracker.IncrConnections()
+	tracker.IncrConnections()
+
+	got := tracker.ConnectionsSinceBoot()
+	if got != 3 {
+		t.Errorf(
+			"expected 3 connections, got %d", got,
+		)
+	}
+}
+
+func TestIncrSessions(t *testing.T) {
+	t.Parallel()
+
+	tracker := stats.New()
+
+	tracker.IncrSessions()
+	tracker.IncrSessions()
+
+	got := tracker.SessionsSinceBoot()
+	if got != 2 {
+		t.Errorf(
+			"expected 2 sessions, got %d", got,
+		)
+	}
+}
+
+func TestIncrMessages(t *testing.T) {
+	t.Parallel()
+
+	tracker := stats.New()
+
+	tracker.IncrMessages()
+
+	got := tracker.MessagesSinceBoot()
+	if got != 1 {
+		t.Errorf(
+			"expected 1 message, got %d", got,
+		)
+	}
+}
+
+func TestCountersAreIndependent(t *testing.T) {
+	t.Parallel()
+
+	tracker := stats.New()
+
+	tracker.IncrConnections()
+	tracker.IncrSessions()
+	tracker.IncrMessages()
+	tracker.IncrMessages()
+
+	if tracker.ConnectionsSinceBoot() != 1 {
+		t.Errorf(
+			"expected 1 connection, got %d",
+			tracker.ConnectionsSinceBoot(),
+		)
+	}
+
+	if tracker.SessionsSinceBoot() != 1 {
+		t.Errorf(
+			"expected 1 session, got %d",
+			tracker.SessionsSinceBoot(),
+		)
+	}
+
+	if tracker.MessagesSinceBoot() != 2 {
+		t.Errorf(
+			"expected 2 messages, got %d",
+			tracker.MessagesSinceBoot(),
+		)
+	}
+}

pkg/irc/commands.go

@@ -11,6 +11,7 @@ const (
 	CmdNames   = "NAMES"
 	CmdNick    = "NICK"
 	CmdNotice  = "NOTICE"
+	CmdPass    = "PASS"
 	CmdPart    = "PART"
 	CmdPing    = "PING"
 	CmdPong    = "PONG"

pkg/irc/numerics.go

@@ -0,0 +1,391 @@
+// Package irc provides constants and utilities for the
+// IRC protocol, including numeric reply codes from
+// RFC 1459 and RFC 2812, and standard command names.
+package irc
+
+import (
+	"errors"
+	"fmt"
+)
+
+// IRCMessageType represents an IRC numeric reply or error code.
+type IRCMessageType int //nolint:revive // Name requested by project owner.
+
+// Name returns the standard IRC name for this numeric code
+// (e.g., IRCMessageType(252).Name() returns "RPL_LUSEROP").
+// Returns an empty string if the code is unknown.
+func (t IRCMessageType) Name() string {
+	return names[t]
+}
+
+// String returns the name and numeric code in angle brackets
+// (e.g., IRCMessageType(252).String() returns "RPL_LUSEROP <252>").
+// If the code is unknown, returns "UNKNOWN <NNN>".
+func (t IRCMessageType) String() string {
+	n := names[t]
+	if n == "" {
+		n = "UNKNOWN"
+	}
+
+	return fmt.Sprintf("%s <%03d>", n, int(t))
+}
+
+// Code returns the three-digit zero-padded string representation
+// of the numeric code (e.g., IRCMessageType(252).Code() returns "252").
+func (t IRCMessageType) Code() string {
+	return fmt.Sprintf("%03d", int(t))
+}
+
+// Int returns the bare integer value of the numeric code.
+func (t IRCMessageType) Int() int {
+	return int(t)
+}
+
+// ErrUnknownNumeric is returned by FromInt when the numeric code is not recognized.
+var ErrUnknownNumeric = errors.New("unknown IRC numeric code")
+
+// FromInt converts an integer to an IRCMessageType, returning an error
+// if the numeric code is not a known IRC reply or error code.
+func FromInt(n int) (IRCMessageType, error) {
+	t := IRCMessageType(n)
+	if _, ok := names[t]; !ok {
+		return 0, fmt.Errorf("%w: %d", ErrUnknownNumeric, n)
+	}
+
+	return t, nil
+}
+
+// Connection registration replies (001-005).
+const (
+	RplWelcome  IRCMessageType = 1
+	RplYourHost IRCMessageType = 2
+	RplCreated  IRCMessageType = 3
+	RplMyInfo   IRCMessageType = 4
+	RplBounce   IRCMessageType = 5 // RFC 2812; also known as RPL_ISUPPORT in practice
+	RplIsupport IRCMessageType = 5 // De-facto standard (same numeric as RplBounce)
+)
+
+// Command responses (200-399).
+const (
+	// RFC 2812 trace/stats/links replies (200-219).
+	RplTraceLink       IRCMessageType = 200
+	RplTraceConnecting IRCMessageType = 201
+	RplTraceHandshake  IRCMessageType = 202
+	RplTraceUnknown    IRCMessageType = 203
+	RplTraceOperator   IRCMessageType = 204
+	RplTraceUser       IRCMessageType = 205
+	RplTraceServer     IRCMessageType = 206
+	RplTraceService    IRCMessageType = 207
+	RplTraceNewType    IRCMessageType = 208
+	RplTraceClass      IRCMessageType = 209
+	RplStatsLinkInfo   IRCMessageType = 211
+	RplStatsCommands   IRCMessageType = 212
+	RplStatsCLine      IRCMessageType = 213
+	RplStatsNLine      IRCMessageType = 214
+	RplStatsILine      IRCMessageType = 215
+	RplStatsKLine      IRCMessageType = 216
+	RplStatsQLine      IRCMessageType = 217
+	RplStatsYLine      IRCMessageType = 218
+	RplEndOfStats      IRCMessageType = 219
+
+	RplUmodeIs      IRCMessageType = 221
+	RplServList     IRCMessageType = 234
+	RplServListEnd  IRCMessageType = 235
+	RplStatsLLine   IRCMessageType = 241
+	RplStatsUptime  IRCMessageType = 242
+	RplStatsOLine   IRCMessageType = 243
+	RplStatsHLine   IRCMessageType = 244
+	RplLuserClient  IRCMessageType = 251
+	RplLuserOp      IRCMessageType = 252
+	RplLuserUnknown IRCMessageType = 253
+
+	RplLuserChannels IRCMessageType = 254
+	RplLuserMe       IRCMessageType = 255
+	RplAdminMe       IRCMessageType = 256
+	RplAdminLoc1     IRCMessageType = 257
+	RplAdminLoc2     IRCMessageType = 258
+	RplAdminEmail    IRCMessageType = 259
+	RplTraceLog      IRCMessageType = 261
+	RplTraceEnd      IRCMessageType = 262
+	RplTryAgain      IRCMessageType = 263
+
+	RplAway          IRCMessageType = 301
+	RplUserHost      IRCMessageType = 302
+	RplIson          IRCMessageType = 303
+	RplUnaway        IRCMessageType = 305
+	RplNowAway       IRCMessageType = 306
+	RplWhoisUser     IRCMessageType = 311
+	RplWhoisServer   IRCMessageType = 312
+	RplWhoisOperator IRCMessageType = 313
+	RplWhoWasUser    IRCMessageType = 314
+	RplEndOfWho      IRCMessageType = 315
+	RplWhoisIdle     IRCMessageType = 317
+	RplEndOfWhois    IRCMessageType = 318
+	RplWhoisChannels IRCMessageType = 319
+	RplListStart     IRCMessageType = 321
+	RplList          IRCMessageType = 322
+	RplListEnd       IRCMessageType = 323
+	RplChannelModeIs IRCMessageType = 324
+
+	RplUniqOpIs        IRCMessageType = 325
+	RplCreationTime    IRCMessageType = 329
+	RplNoTopic         IRCMessageType = 331
+	RplTopic           IRCMessageType = 332
+	RplTopicWhoTime    IRCMessageType = 333
+	RplInviting        IRCMessageType = 341
+	RplSummoning       IRCMessageType = 342
+	RplInviteList      IRCMessageType = 346
+	RplEndOfInviteList IRCMessageType = 347
+	RplExceptList      IRCMessageType = 348
+	RplEndOfExceptList IRCMessageType = 349
+	RplVersion         IRCMessageType = 351
+	RplWhoReply        IRCMessageType = 352
+	RplNamReply        IRCMessageType = 353
+	RplLinks           IRCMessageType = 364
+	RplEndOfLinks      IRCMessageType = 365
+	RplEndOfNames      IRCMessageType = 366
+	RplBanList         IRCMessageType = 367
+	RplEndOfBanList    IRCMessageType = 368
+	RplEndOfWhowas     IRCMessageType = 369
+	RplInfo            IRCMessageType = 371
+	RplMotd            IRCMessageType = 372
+	RplEndOfInfo       IRCMessageType = 374
+	RplMotdStart       IRCMessageType = 375
+	RplEndOfMotd       IRCMessageType = 376
+	RplYoureOper       IRCMessageType = 381
+	RplRehashing       IRCMessageType = 382
+	RplYoureService    IRCMessageType = 383
+	RplTime            IRCMessageType = 391
+	RplUsersStart      IRCMessageType = 392
+	RplUsers           IRCMessageType = 393
+	RplEndOfUsers      IRCMessageType = 394
+	RplNoUsers         IRCMessageType = 395
+)
+
+// Error replies (400-599).
+const (
+	ErrNoSuchNick       IRCMessageType = 401
+	ErrNoSuchServer     IRCMessageType = 402
+	ErrNoSuchChannel    IRCMessageType = 403
+	ErrCannotSendToChan IRCMessageType = 404
+	ErrTooManyChannels  IRCMessageType = 405
+	ErrWasNoSuchNick    IRCMessageType = 406
+	ErrTooManyTargets   IRCMessageType = 407
+	ErrNoSuchService    IRCMessageType = 408
+	ErrNoOrigin         IRCMessageType = 409
+	ErrNoRecipient      IRCMessageType = 411
+	ErrNoTextToSend     IRCMessageType = 412
+	ErrNoTopLevel       IRCMessageType = 413
+	ErrWildTopLevel     IRCMessageType = 414
+	ErrBadMask          IRCMessageType = 415
+	ErrUnknownCommand   IRCMessageType = 421
+	ErrNoMotd           IRCMessageType = 422
+	ErrNoAdminInfo      IRCMessageType = 423
+	ErrFileError        IRCMessageType = 424
+	ErrNoNicknameGiven  IRCMessageType = 431
+	ErrErroneusNickname IRCMessageType = 432
+	ErrNicknameInUse    IRCMessageType = 433
+	ErrNickCollision    IRCMessageType = 436
+	ErrUnavailResource  IRCMessageType = 437
+
+	ErrUserNotInChannel  IRCMessageType = 441
+	ErrNotOnChannel      IRCMessageType = 442
+	ErrUserOnChannel     IRCMessageType = 443
+	ErrNoLogin           IRCMessageType = 444
+	ErrSummonDisabled    IRCMessageType = 445
+	ErrUsersDisabled     IRCMessageType = 446
+	ErrNotRegistered     IRCMessageType = 451
+	ErrNeedMoreParams    IRCMessageType = 461
+	ErrAlreadyRegistered IRCMessageType = 462
+	ErrNoPermForHost     IRCMessageType = 463
+	ErrPasswdMismatch    IRCMessageType = 464
+	ErrYoureBannedCreep  IRCMessageType = 465
+	ErrYouWillBeBanned   IRCMessageType = 466
+	ErrKeySet            IRCMessageType = 467
+	ErrChannelIsFull     IRCMessageType = 471
+	ErrUnknownMode       IRCMessageType = 472
+	ErrInviteOnlyChan    IRCMessageType = 473
+	ErrBannedFromChan    IRCMessageType = 474
+	ErrBadChannelKey     IRCMessageType = 475
+	ErrBadChanMask       IRCMessageType = 476
+	ErrNoChanModes       IRCMessageType = 477
+	ErrBanListFull       IRCMessageType = 478
+	ErrNoPrivileges      IRCMessageType = 481
+	ErrChanOpPrivsNeeded IRCMessageType = 482
+	ErrCantKillServer    IRCMessageType = 483
+	ErrRestricted        IRCMessageType = 484
+	ErrUniqOpPrivsNeeded IRCMessageType = 485
+	ErrNoOperHost        IRCMessageType = 491
+
+	ErrUmodeUnknownFlag IRCMessageType = 501
+	ErrUsersDoNotMatch  IRCMessageType = 502
+)
+
+// names maps numeric codes to their standard IRC names.
+//
+//nolint:gochecknoglobals
+var names = map[IRCMessageType]string{
+	RplWelcome:  "RPL_WELCOME",
+	RplYourHost: "RPL_YOURHOST",
+	RplCreated:  "RPL_CREATED",
+	RplMyInfo:   "RPL_MYINFO",
+	RplBounce:   "RPL_BOUNCE",
+
+	RplTraceLink:       "RPL_TRACELINK",
+	RplTraceConnecting: "RPL_TRACECONNECTING",
+	RplTraceHandshake:  "RPL_TRACEHANDSHAKE",
+	RplTraceUnknown:    "RPL_TRACEUNKNOWN",
+	RplTraceOperator:   "RPL_TRACEOPERATOR",
+	RplTraceUser:       "RPL_TRACEUSER",
+	RplTraceServer:     "RPL_TRACESERVER",
+	RplTraceService:    "RPL_TRACESERVICE",
+	RplTraceNewType:    "RPL_TRACENEWTYPE",
+	RplTraceClass:      "RPL_TRACECLASS",
+	RplStatsLinkInfo:   "RPL_STATSLINKINFO",
+	RplStatsCommands:   "RPL_STATSCOMMANDS",
+	RplStatsCLine:      "RPL_STATSCLINE",
+	RplStatsNLine:      "RPL_STATSNLINE",
+	RplStatsILine:      "RPL_STATSILINE",
+	RplStatsKLine:      "RPL_STATSKLINE",
+	RplStatsQLine:      "RPL_STATSQLINE",
+	RplStatsYLine:      "RPL_STATSYLINE",
+	RplEndOfStats:      "RPL_ENDOFSTATS",
+
+	RplUmodeIs:      "RPL_UMODEIS",
+	RplServList:     "RPL_SERVLIST",
+	RplServListEnd:  "RPL_SERVLISTEND",
+	RplStatsLLine:   "RPL_STATSLLINE",
+	RplStatsUptime:  "RPL_STATSUPTIME",
+	RplStatsOLine:   "RPL_STATSOLINE",
+	RplStatsHLine:   "RPL_STATSHLINE",
+	RplLuserClient:  "RPL_LUSERCLIENT",
+	RplLuserOp:      "RPL_LUSEROP",
+	RplLuserUnknown: "RPL_LUSERUNKNOWN",
+
+	RplLuserChannels: "RPL_LUSERCHANNELS",
+	RplLuserMe:       "RPL_LUSERME",
+	RplAdminMe:       "RPL_ADMINME",
+	RplAdminLoc1:     "RPL_ADMINLOC1",
+	RplAdminLoc2:     "RPL_ADMINLOC2",
+	RplAdminEmail:    "RPL_ADMINEMAIL",
+	RplTraceLog:      "RPL_TRACELOG",
+	RplTraceEnd:      "RPL_TRACEEND",
+	RplTryAgain:      "RPL_TRYAGAIN",
+
+	RplAway:          "RPL_AWAY",
+	RplUserHost:      "RPL_USERHOST",
+	RplIson:          "RPL_ISON",
+	RplUnaway:        "RPL_UNAWAY",
+	RplNowAway:       "RPL_NOWAWAY",
+	RplWhoisUser:     "RPL_WHOISUSER",
+	RplWhoisServer:   "RPL_WHOISSERVER",
+	RplWhoisOperator: "RPL_WHOISOPERATOR",
+	RplWhoWasUser:    "RPL_WHOWASUSER",
+	RplEndOfWho:      "RPL_ENDOFWHO",
+	RplWhoisIdle:     "RPL_WHOISIDLE",
+	RplEndOfWhois:    "RPL_ENDOFWHOIS",
+	RplWhoisChannels: "RPL_WHOISCHANNELS",
+	RplListStart:     "RPL_LISTSTART",
+	RplList:          "RPL_LIST",
+	RplListEnd:       "RPL_LISTEND", //nolint:misspell
+	RplChannelModeIs: "RPL_CHANNELMODEIS",
+
+	RplUniqOpIs:        "RPL_UNIQOPIS",
+	RplCreationTime:    "RPL_CREATIONTIME",
+	RplNoTopic:         "RPL_NOTOPIC",
+	RplTopic:           "RPL_TOPIC",
+	RplTopicWhoTime:    "RPL_TOPICWHOTIME",
+	RplInviting:        "RPL_INVITING",
+	RplSummoning:       "RPL_SUMMONING",
+	RplInviteList:      "RPL_INVITELIST",
+	RplEndOfInviteList: "RPL_ENDOFINVITELIST",
+	RplExceptList:      "RPL_EXCEPTLIST",
+	RplEndOfExceptList: "RPL_ENDOFEXCEPTLIST",
+	RplVersion:         "RPL_VERSION",
+	RplWhoReply:        "RPL_WHOREPLY",
+	RplNamReply:        "RPL_NAMREPLY",
+	RplLinks:           "RPL_LINKS",
+	RplEndOfLinks:      "RPL_ENDOFLINKS",
+	RplEndOfNames:      "RPL_ENDOFNAMES",
+	RplBanList:         "RPL_BANLIST",
+	RplEndOfBanList:    "RPL_ENDOFBANLIST",
+	RplEndOfWhowas:     "RPL_ENDOFWHOWAS",
+	RplInfo:            "RPL_INFO",
+	RplMotd:            "RPL_MOTD",
+	RplEndOfInfo:       "RPL_ENDOFINFO",
+	RplMotdStart:       "RPL_MOTDSTART",
+	RplEndOfMotd:       "RPL_ENDOFMOTD",
+	RplYoureOper:       "RPL_YOUREOPER",
+	RplRehashing:       "RPL_REHASHING",
+	RplYoureService:    "RPL_YOURESERVICE",
+	RplTime:            "RPL_TIME",
+	RplUsersStart:      "RPL_USERSSTART",
+	RplUsers:           "RPL_USERS",
+	RplEndOfUsers:      "RPL_ENDOFUSERS",
+	RplNoUsers:         "RPL_NOUSERS",
+
+	ErrNoSuchNick:       "ERR_NOSUCHNICK",
+	ErrNoSuchServer:     "ERR_NOSUCHSERVER",
+	ErrNoSuchChannel:    "ERR_NOSUCHCHANNEL",
+	ErrCannotSendToChan: "ERR_CANNOTSENDTOCHAN",
+	ErrTooManyChannels:  "ERR_TOOMANYCHANNELS",
+	ErrWasNoSuchNick:    "ERR_WASNOSUCHNICK",
+	ErrTooManyTargets:   "ERR_TOOMANYTARGETS",
+	ErrNoSuchService:    "ERR_NOSUCHSERVICE",
+	ErrNoOrigin:         "ERR_NOORIGIN",
+	ErrNoRecipient:      "ERR_NORECIPIENT",
+	ErrNoTextToSend:     "ERR_NOTEXTTOSEND",
+	ErrNoTopLevel:       "ERR_NOTOPLEVEL",
+	ErrWildTopLevel:     "ERR_WILDTOPLEVEL",
+	ErrBadMask:          "ERR_BADMASK",
+	ErrUnknownCommand:   "ERR_UNKNOWNCOMMAND",
+	ErrNoMotd:           "ERR_NOMOTD",
+	ErrNoAdminInfo:      "ERR_NOADMININFO",
+	ErrFileError:        "ERR_FILEERROR",
+	ErrNoNicknameGiven:  "ERR_NONICKNAMEGIVEN",
+	ErrErroneusNickname: "ERR_ERRONEUSNICKNAME",
+	ErrNicknameInUse:    "ERR_NICKNAMEINUSE",
+	ErrNickCollision:    "ERR_NICKCOLLISION",
+	ErrUnavailResource:  "ERR_UNAVAILRESOURCE",
+
+	ErrUserNotInChannel:  "ERR_USERNOTINCHANNEL",
+	ErrNotOnChannel:      "ERR_NOTONCHANNEL",
+	ErrUserOnChannel:     "ERR_USERONCHANNEL",
+	ErrNoLogin:           "ERR_NOLOGIN",
+	ErrSummonDisabled:    "ERR_SUMMONDISABLED",
+	ErrUsersDisabled:     "ERR_USERSDISABLED",
+	ErrNotRegistered:     "ERR_NOTREGISTERED",
+	ErrNeedMoreParams:    "ERR_NEEDMOREPARAMS",
+	ErrAlreadyRegistered: "ERR_ALREADYREGISTERED",
+	ErrNoPermForHost:     "ERR_NOPERMFORHOST",
+	ErrPasswdMismatch:    "ERR_PASSWDMISMATCH",
+	ErrYoureBannedCreep:  "ERR_YOUREBANNEDCREEP",
+	ErrYouWillBeBanned:   "ERR_YOUWILLBEBANNED",
+	ErrKeySet:            "ERR_KEYSET",
+	ErrChannelIsFull:     "ERR_CHANNELISFULL",
+	ErrUnknownMode:       "ERR_UNKNOWNMODE",
+	ErrInviteOnlyChan:    "ERR_INVITEONLYCHAN",
+	ErrBannedFromChan:    "ERR_BANNEDFROMCHAN",
+	ErrBadChannelKey:     "ERR_BADCHANNELKEY",
+	ErrBadChanMask:       "ERR_BADCHANMASK",
+	ErrNoChanModes:       "ERR_NOCHANMODES",
+	ErrBanListFull:       "ERR_BANLISTFULL",
+	ErrNoPrivileges:      "ERR_NOPRIVILEGES",
+	ErrChanOpPrivsNeeded: "ERR_CHANOPRIVSNEEDED",
+	ErrCantKillServer:    "ERR_CANTKILLSERVER",
+	ErrRestricted:        "ERR_RESTRICTED",
+	ErrUniqOpPrivsNeeded: "ERR_UNIQOPPRIVSNEEDED",
+	ErrNoOperHost:        "ERR_NOOPERHOST",
+
+	ErrUmodeUnknownFlag: "ERR_UMODEUNKNOWNFLAG",
+	ErrUsersDoNotMatch:  "ERR_USERSDONTMATCH",
+}
+
+// Name returns the standard IRC name for a numeric code
+// (e.g., Name(2) returns "RPL_YOURHOST"). Returns an
+// empty string if the code is unknown.
+//
+// Deprecated: Use IRCMessageType.Name() instead.
+func Name(code IRCMessageType) string {
+	return names[code]
+}

pkg/irc/numerics_test.go

@@ -0,0 +1,163 @@
+package irc_test
+
+import (
+	"errors"
+	"testing"
+
+	"git.eeqj.de/sneak/neoirc/pkg/irc"
+)
+
+func TestName(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		numeric irc.IRCMessageType
+		want    string
+	}{
+		{irc.RplWelcome, "RPL_WELCOME"},
+		{irc.RplBounce, "RPL_BOUNCE"},
+		{irc.RplLuserOp, "RPL_LUSEROP"},
+		{irc.ErrCannotSendToChan, "ERR_CANNOTSENDTOCHAN"},
+		{irc.ErrNicknameInUse, "ERR_NICKNAMEINUSE"},
+	}
+
+	for _, tc := range tests {
+		if got := tc.numeric.Name(); got != tc.want {
+			t.Errorf("IRCMessageType(%d).Name() = %q, want %q", tc.numeric.Int(), got, tc.want)
+		}
+	}
+}
+
+func TestString(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		numeric irc.IRCMessageType
+		want    string
+	}{
+		{irc.RplWelcome, "RPL_WELCOME <001>"},
+		{irc.RplBounce, "RPL_BOUNCE <005>"},
+		{irc.RplLuserOp, "RPL_LUSEROP <252>"},
+		{irc.ErrCannotSendToChan, "ERR_CANNOTSENDTOCHAN <404>"},
+	}
+
+	for _, tc := range tests {
+		if got := tc.numeric.String(); got != tc.want {
+			t.Errorf("IRCMessageType(%d).String() = %q, want %q", tc.numeric.Int(), got, tc.want)
+		}
+	}
+}
+
+func TestCode(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		numeric irc.IRCMessageType
+		want    string
+	}{
+		{irc.RplWelcome, "001"},
+		{irc.RplBounce, "005"},
+		{irc.RplLuserOp, "252"},
+		{irc.ErrCannotSendToChan, "404"},
+	}
+
+	for _, tc := range tests {
+		if got := tc.numeric.Code(); got != tc.want {
+			t.Errorf("IRCMessageType(%d).Code() = %q, want %q", tc.numeric.Int(), got, tc.want)
+		}
+	}
+}
+
+func TestInt(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		numeric irc.IRCMessageType
+		want    int
+	}{
+		{irc.RplWelcome, 1},
+		{irc.RplBounce, 5},
+		{irc.RplLuserOp, 252},
+		{irc.ErrCannotSendToChan, 404},
+	}
+
+	for _, tc := range tests {
+		if got := tc.numeric.Int(); got != tc.want {
+			t.Errorf("IRCMessageType(%d).Int() = %d, want %d", tc.want, got, tc.want)
+		}
+	}
+}
+
+func TestFromInt_Known(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		code int
+		want irc.IRCMessageType
+	}{
+		{1, irc.RplWelcome},
+		{5, irc.RplBounce},
+		{252, irc.RplLuserOp},
+		{404, irc.ErrCannotSendToChan},
+		{433, irc.ErrNicknameInUse},
+	}
+
+	for _, test := range tests {
+		got, err := irc.FromInt(test.code)
+		if err != nil {
+			t.Errorf("FromInt(%d) returned unexpected error: %v", test.code, err)
+
+			continue
+		}
+
+		if got != test.want {
+			t.Errorf("FromInt(%d) = %v, want %v", test.code, got, test.want)
+		}
+	}
+}
+
+func TestFromInt_Unknown(t *testing.T) {
+	t.Parallel()
+
+	unknowns := []int{0, 999, 600, -1}
+	for _, code := range unknowns {
+		_, err := irc.FromInt(code)
+		if err == nil {
+			t.Errorf("FromInt(%d) expected error, got nil", code)
+
+			continue
+		}
+
+		if !errors.Is(err, irc.ErrUnknownNumeric) {
+			t.Errorf("FromInt(%d) error = %v, want ErrUnknownNumeric", code, err)
+		}
+	}
+}
+
+func TestUnknownNumeric_Name(t *testing.T) {
+	t.Parallel()
+
+	unknown := irc.IRCMessageType(999)
+	if got := unknown.Name(); got != "" {
+		t.Errorf("IRCMessageType(999).Name() = %q, want empty string", got)
+	}
+}
+
+func TestUnknownNumeric_String(t *testing.T) {
+	t.Parallel()
+
+	unknown := irc.IRCMessageType(999)
+	want := "UNKNOWN <999>"
+
+	if got := unknown.String(); got != want {
+		t.Errorf("IRCMessageType(999).String() = %q, want %q", got, want)
+	}
+}
+
+func TestDeprecatedNameFunc(t *testing.T) {
+	t.Parallel()
+
+	if got := irc.Name(irc.RplYourHost); got != "RPL_YOURHOST" {
+		t.Errorf("Name(RplYourHost) = %q, want %q", got, "RPL_YOURHOST")
+	}
+}

web/src/app.jsx

@@ -8,6 +8,56 @@ const MEMBER_REFRESH_INTERVAL = 10000;
 const ACTION_PREFIX = "\x01ACTION ";
 const ACTION_SUFFIX = "\x01";
 
+// Hashcash proof-of-work helpers using Web Crypto API.
+
+function checkLeadingZeros(hashBytes, bits) {
+  let count = 0;
+  for (let i = 0; i < hashBytes.length; i++) {
+    if (hashBytes[i] === 0) {
+      count += 8;
+      continue;
+    }
+    let b = hashBytes[i];
+    while ((b & 0x80) === 0) {
+      count++;
+      b <<= 1;
+    }
+    break;
+  }
+  return count >= bits;
+}
+
+async function mintHashcash(bits, resource) {
+  const encoder = new TextEncoder();
+  const now = new Date();
+  const date =
+    String(now.getUTCFullYear()).slice(2) +
+    String(now.getUTCMonth() + 1).padStart(2, "0") +
+    String(now.getUTCDate()).padStart(2, "0");
+  const prefix = `1:${bits}:${date}:${resource}::`;
+  let nonce = Math.floor(Math.random() * 0x100000);
+  const batchSize = 1024;
+
+  for (;;) {
+    const stamps = [];
+    const hashPromises = [];
+    for (let i = 0; i < batchSize; i++) {
+      const stamp = prefix + (nonce + i).toString(16);
+      stamps.push(stamp);
+      hashPromises.push(
+        crypto.subtle.digest("SHA-256", encoder.encode(stamp)),
+      );
+    }
+    const hashes = await Promise.all(hashPromises);
+    for (let i = 0; i < hashes.length; i++) {
+      if (checkLeadingZeros(new Uint8Array(hashes[i]), bits)) {
+        return stamps[i];
+      }
+    }
+    nonce += batchSize;
+  }
+}
+
 function api(path, opts = {}) {
   const token = localStorage.getItem("neoirc_token");
   const headers = {
@@ -60,12 +110,16 @@ function LoginScreen({ onLogin }) {
   const [motd, setMotd] = useState("");
   const [serverName, setServerName] = useState("NeoIRC");
   const inputRef = useRef();
+  const hashcashBitsRef = useRef(0);
+  const hashcashResourceRef = useRef("neoirc");
 
   useEffect(() => {
     api("/server")
       .then((s) => {
         if (s.name) setServerName(s.name);
         if (s.motd) setMotd(s.motd);
+        hashcashBitsRef.current = s.hashcash_bits || 0;
+        if (s.name) hashcashResourceRef.current = s.name;
       })
       .catch(() => {});
     const saved = localStorage.getItem("neoirc_token");
@@ -81,9 +135,22 @@ function LoginScreen({ onLogin }) {
     e.preventDefault();
     setError("");
     try {
+      let hashcashStamp = "";
+      if (hashcashBitsRef.current > 0) {
+        setError("Computing proof-of-work...");
+        hashcashStamp = await mintHashcash(
+          hashcashBitsRef.current,
+          hashcashResourceRef.current,
+        );
+        setError("");
+      }
+      const reqBody = { nick: nick.trim() };
+      if (hashcashStamp) {
+        reqBody.pow_token = hashcashStamp;
+      }
       const res = await api("/session", {
         method: "POST",
-        body: JSON.stringify({ nick: nick.trim() }),
+        body: JSON.stringify(reqBody),
       });
       localStorage.setItem("neoirc_token", res.token);
       onLogin(res.nick);