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>

internal/hub/hub.go

@@ -0,0 +1,116 @@
+// Package hub is the Bubble Tea model every BBS session lands in (PRD §4.1):
+// it lists registered plugins and routes the session to the selection,
+// reclaiming it when the plugin emits ExitMsg.
+package hub
+
+import (
+	"fmt"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+
+	"github.com/profullstack/agentbbs/internal/auth"
+	"github.com/profullstack/agentbbs/internal/plugin"
+)
+
+var (
+	titleStyle  = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#4ade80"))
+	dimStyle    = lipgloss.NewStyle().Foreground(lipgloss.Color("241"))
+	cursorStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#4ade80"))
+	lockStyle   = lipgloss.NewStyle().Foreground(lipgloss.Color("203"))
+	frameStyle  = lipgloss.NewStyle().Padding(1, 2)
+)
+
+// Model is the hub menu.
+type Model struct {
+	user    auth.User
+	ctx     plugin.Context
+	plugins []plugin.Plugin
+
+	cursor int
+	active tea.Model
+	width  int
+	height int
+	note   string
+}
+
+// New builds a hub for one session.
+func New(user auth.User, ctx plugin.Context, plugins []plugin.Plugin) Model {
+	return Model{user: user, ctx: ctx, plugins: plugins}
+}
+
+func (m Model) Init() tea.Cmd { return nil }
+
+func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	// Window size is shared with whichever model is active.
+	if ws, ok := msg.(tea.WindowSizeMsg); ok {
+		m.width, m.height = ws.Width, ws.Height
+	}
+
+	// A plugin owns the session until it emits ExitMsg (PRD §4.3).
+	if m.active != nil {
+		if _, ok := msg.(plugin.ExitMsg); ok {
+			m.active = nil
+			return m, nil
+		}
+		next, cmd := m.active.Update(msg)
+		m.active = next
+		return m, cmd
+	}
+
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		m.note = ""
+		switch msg.String() {
+		case "q", "ctrl+c", "esc":
+			return m, tea.Quit
+		case "up", "k":
+			if m.cursor > 0 {
+				m.cursor--
+			}
+		case "down", "j":
+			if m.cursor < len(m.plugins)-1 {
+				m.cursor++
+			}
+		case "enter":
+			p := m.plugins[m.cursor]
+			if p.RequiresAuth() && m.user.Kind == auth.Guest {
+				m.note = "members only — ssh join@ to register"
+				return m, nil
+			}
+			m.active = p.New(m.user, m.ctx)
+			cmds := []tea.Cmd{m.active.Init()}
+			if m.width > 0 {
+				next, cmd := m.active.Update(tea.WindowSizeMsg{Width: m.width, Height: m.height})
+				m.active = next
+				cmds = append(cmds, cmd)
+			}
+			return m, tea.Batch(cmds...)
+		}
+	}
+	return m, nil
+}
+
+func (m Model) View() string {
+	if m.active != nil {
+		return m.active.View()
+	}
+	who := fmt.Sprintf("%s (%s)", m.user.Name, m.user.Kind)
+	s := titleStyle.Render("AgentBBS") + dimStyle.Render("  ·  "+who) + "\n\n"
+	for i, p := range m.plugins {
+		cur := "  "
+		if i == m.cursor {
+			cur = cursorStyle.Render("> ")
+		}
+		label := p.Title()
+		if p.RequiresAuth() && m.user.Kind == auth.Guest {
+			label += lockStyle.Render("  [members]")
+		}
+		s += fmt.Sprintf("%s%s\n  %s\n", cur, label, dimStyle.Render(p.Description()))
+	}
+	s += "\n" + dimStyle.Render("↑/↓ move · enter select · q quit")
+	if m.note != "" {
+		s += "\n" + lockStyle.Render(m.note)
+	}
+	return frameStyle.Render(s)
+}