AgentBBS: M0 core hub, M1 arcade, pods with CoinPay membership

A modern BBS over SSH for humans and AI agents (docs/PRD.md), plus the
pods addendum (docs/pods.md). Go + charmbracelet (wish/bubbletea).

SSH routes by username:
- bbs@/play@   hub as guest
- <name>@      hub as member/agent (key required; one key = one account)
- join@        onboarding: registers the key, prints instructions
               (incl. coinpay pay command with HMAC payment ref), kicks
- pod@         personal Linux container, paid membership $1/mo via
               CoinPay; rootless podman preferred, hardened docker
               fallback (cap-drop ALL, no-new-privileges, uid 1000,
               cpu/mem/pids caps, per-user volume)

M0: plugin contract (ID/Title/Description/RequiresAuth/New + ExitMsg),
hub menu, SQLite store (users/sessions/scores/pod_subscriptions),
session audit, grant-pod ops command.

M1 arcade: doom-ascii + Freedoom via scripts/fetch-assets.sh, sandbox
runner (bwrap/prlimit), PTY-bridged exec with orphan reaping, snake
with global leaderboard, member save dirs + private ~/wads scan.

Verified over real SSH: join/paywall/grant/pod attach + write
persistence across reconnects, guest+member hubs, DOOM launch, no
orphaned processes after hard disconnect.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

plugins/arcade/snake.go

@@ -0,0 +1,169 @@
+package arcade
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+
+	"github.com/profullstack/agentbbs/internal/auth"
+	"github.com/profullstack/agentbbs/internal/plugin"
+)
+
+// snake is the built-in leaderboard game: simple, fair, trivially judged.
+type snake struct {
+	user auth.User
+	ctx  plugin.Context
+
+	w, h  int // board size in cells
+	body  []pos
+	dir   pos
+	food  pos
+	score int64
+	dead  bool
+	saved bool
+}
+
+type pos struct{ x, y int }
+
+type tickMsg time.Time
+
+func tick() tea.Cmd {
+	return tea.Tick(120*time.Millisecond, func(t time.Time) tea.Msg { return tickMsg(t) })
+}
+
+func newSnake(user auth.User, ctx plugin.Context, termW, termH int) *snake {
+	w, h := 32, 16
+	if termW > 0 && termW/2-4 < w {
+		w = termW/2 - 4
+	}
+	if termH > 0 && termH-8 < h {
+		h = termH - 8
+	}
+	if w < 10 {
+		w = 10
+	}
+	if h < 8 {
+		h = 8
+	}
+	s := &snake{user: user, ctx: ctx, w: w, h: h,
+		body: []pos{{w / 2, h / 2}}, dir: pos{1, 0}}
+	s.placeFood()
+	return s
+}
+
+func (s *snake) placeFood() {
+	for {
+		p := pos{rand.Intn(s.w), rand.Intn(s.h)}
+		if !s.hits(p) {
+			s.food = p
+			return
+		}
+	}
+}
+
+func (s *snake) hits(p pos) bool {
+	for _, b := range s.body {
+		if b == p {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *snake) Init() tea.Cmd { return tick() }
+
+func (s *snake) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "q", "esc":
+			return s, back
+		case "up", "w":
+			if s.dir.y == 0 {
+				s.dir = pos{0, -1}
+			}
+		case "down", "s":
+			if s.dir.y == 0 {
+				s.dir = pos{0, 1}
+			}
+		case "left", "a":
+			if s.dir.x == 0 {
+				s.dir = pos{-1, 0}
+			}
+		case "right", "d":
+			if s.dir.x == 0 {
+				s.dir = pos{1, 0}
+			}
+		case "r":
+			if s.dead {
+				ns := newSnake(s.user, s.ctx, 0, 0)
+				ns.w, ns.h = s.w, s.h
+				return ns, ns.Init()
+			}
+		}
+	case tickMsg:
+		if s.dead {
+			return s, nil
+		}
+		head := pos{s.body[0].x + s.dir.x, s.body[0].y + s.dir.y}
+		if head.x < 0 || head.y < 0 || head.x >= s.w || head.y >= s.h || s.hits(head) {
+			s.dead = true
+			// Guests play, members persist (PRD §5.1).
+			if !s.saved && s.user.Kind != auth.Guest && s.user.StoreID > 0 && s.score > 0 {
+				_ = s.ctx.Store.AddScore(s.user.StoreID, "snake", s.score)
+				s.saved = true
+			}
+			return s, nil
+		}
+		s.body = append([]pos{head}, s.body...)
+		if head == s.food {
+			s.score += 10
+			s.placeFood()
+		} else {
+			s.body = s.body[:len(s.body)-1]
+		}
+		return s, tick()
+	}
+	return s, nil
+}
+
+var (
+	snakeStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#4ade80"))
+	foodStyle  = lipgloss.NewStyle().Foreground(lipgloss.Color("203"))
+	wallStyle  = lipgloss.NewStyle().Foreground(lipgloss.Color("241"))
+)
+
+func (s *snake) View() string {
+	out := fmt.Sprintf("Snake — score %d", s.score)
+	if s.dead {
+		out += "  ☠  dead (r restart · q back)"
+	}
+	out += "\n" + wallStyle.Render("┌"+repeat("──", s.w)+"┐") + "\n"
+	for y := 0; y < s.h; y++ {
+		row := wallStyle.Render("│")
+		for x := 0; x < s.w; x++ {
+			switch {
+			case s.hits(pos{x, y}):
+				row += snakeStyle.Render("██")
+			case s.food == pos{x, y}:
+				row += foodStyle.Render("◆ ")
+			default:
+				row += "  "
+			}
+		}
+		out += row + wallStyle.Render("│") + "\n"
+	}
+	out += wallStyle.Render("└" + repeat("──", s.w) + "┘")
+	return lipgloss.NewStyle().Padding(1, 2).Render(out)
+}
+
+func repeat(s string, n int) string {
+	out := ""
+	for i := 0; i < n; i++ {
+		out += s
+	}
+	return out
+}