feat(arcade): add Hangman built-in game + leaderboard

Hangman joins Snake as a built-in, leaderboard-backed TUI game (PRD §5.1).
Endless mode: each solved word banks points (longer words and unused guesses
score more) and deals a fresh word with full lives; the run ends when one word
exhausts all six wrong guesses, persisting the total for members under the
"hangman" score key. Guests play without persisting, same as Snake.

Generalize the leaderboard board to take a game name and split the single
"Leaderboard" row into per-game "Leaderboard — Snake" / "Leaderboard — Hangman"
entries.

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

plugins/arcade/arcade.go

@@ -1,7 +1,7 @@
 // Package arcade is the flagship plugin (PRD §5.1): classic terminal games.
 // DOOM and the 80s arcade classics (Space Invaders, Pac-Man, Tetris, Moon
 // Patrol) run as sandboxed external binaries on a real PTY; built-in TUI games
-// (snake) feed the global leaderboards.
+// (snake, hangman) feed the global leaderboards.
 package arcade
 
 import (
@@ -21,7 +21,9 @@ type Plugin struct{}
 
 func (Plugin) ID() string    { return "arcade" }
 func (Plugin) Title() string { return "Arcade" }
-func (Plugin) Description() string { return "DOOM, Space Invaders, Pac-Man, Tetris, snake & leaderboards" }
+func (Plugin) Description() string {
+	return "DOOM, Space Invaders, Pac-Man, Tetris, snake, hangman & leaderboards"
+}
 func (Plugin) RequiresAuth() bool { return false }
 
 func (Plugin) New(user auth.User, ctx plugin.Context) tea.Model {
@@ -134,10 +136,28 @@ func newMenu(user auth.User, ctx plugin.Context) *menu {
 		},
 		entry{
 			section: "BUILT-IN",
-			label:   "Leaderboard",
+			label:   "Hangman",
-			desc:    "global top scores",
+			desc:    "built-in word game; high scores hit the global leaderboard",
 			run: func(m *menu) (tea.Model, tea.Cmd) {
-				m.child = newBoard(m.ctx)
+				m.child = newHangman(m.user, m.ctx)
+				return m, m.child.Init()
+			},
+		},
+		entry{
+			section: "BUILT-IN",
+			label:   "Leaderboard — Snake",
+			desc:    "global top snake scores",
+			run: func(m *menu) (tea.Model, tea.Cmd) {
+				m.child = newBoard(m.ctx, "snake")
+				return m, m.child.Init()
+			},
+		},
+		entry{
+			section: "BUILT-IN",
+			label:   "Leaderboard — Hangman",
+			desc:    "global top hangman scores",
+			run: func(m *menu) (tea.Model, tea.Cmd) {
+				m.child = newBoard(m.ctx, "hangman")
 				return m, m.child.Init()
 			},
 		},

plugins/arcade/board.go

@@ -10,18 +10,21 @@ import (
 	"github.com/profullstack/agentbbs/internal/ui"
 )
 
-// board renders the global top scores (PRD §5.1 leaderboards).
+// board renders the global top scores for one game (PRD §5.1 leaderboards).
 type board struct {
 	ctx    plugin.Context
+	game   string
 	scores []store.Score
 	err    error
 }
 
-func newBoard(ctx plugin.Context) *board { return &board{ctx: ctx} }
+func newBoard(ctx plugin.Context, game string) *board {
+	return &board{ctx: ctx, game: game}
+}
 
 func (b *board) Init() tea.Cmd {
 	return func() tea.Msg {
-		scores, err := b.ctx.Store.TopScores("snake", 10)
+		scores, err := b.ctx.Store.TopScores(b.game, 10)
 		return boardMsg{scores: scores, err: err}
 	}
 }
@@ -42,7 +45,7 @@ func (b *board) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 }
 
 func (b *board) View() string {
-	s := theme.Title("Leaderboard — snake") + "\n\n"
+	s := theme.Title("Leaderboard — "+b.game) + "\n\n"
 	switch {
 	case b.err != nil:
 		s += ui.Danger.Render("error: " + b.err.Error())

plugins/arcade/hangman.go

@@ -0,0 +1,193 @@
+package arcade
+
+import (
+	"fmt"
+	"math/rand"
+	"strings"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+
+	"github.com/profullstack/agentbbs/internal/auth"
+	"github.com/profullstack/agentbbs/internal/plugin"
+)
+
+// hangman is a built-in leaderboard game: guess the hidden word a letter at a
+// time before the gallows fills. It runs endless — each solved word banks
+// points and deals a fresh word with full lives; the run ends (and the score
+// persists for members) when a single word exhausts all six wrong guesses.
+type hangman struct {
+	user auth.User
+	ctx  plugin.Context
+
+	word    string        // current word, upper-case A–Z
+	guessed map[byte]bool // letters tried this word
+	wrong   int           // wrong guesses on the current word
+	score   int64
+	solved  int  // words solved this run
+	won     bool // current word fully revealed
+	dead    bool // ran out of guesses
+	saved   bool
+}
+
+const hangmanMaxWrong = 6
+
+// hangmanWords is the word bank — common, all-caps, letters only so the masked
+// display and A–Z input stay simple.
+var hangmanWords = []string{
+	"TERMINAL", "SANDBOX", "KEYBOARD", "NETWORK", "PROTOCOL", "FIREWALL",
+	"COMPILER", "VARIABLE", "FUNCTION", "POINTER", "BINARY", "KERNEL",
+	"PACKET", "ROUTER", "CIPHER", "GALLOWS", "ARCADE", "INVADER",
+	"GHOST", "MAZE", "ROCKET", "LASER", "CRATER", "PIXEL",
+	"WIDGET", "BUBBLE", "GOPHER", "DAEMON", "SOCKET", "THREAD",
+	"BUFFER", "MODEM", "CURSOR", "SYNTAX", "MODULE", "VECTOR",
+}
+
+func newHangman(user auth.User, ctx plugin.Context) *hangman {
+	h := &hangman{user: user, ctx: ctx}
+	h.deal()
+	return h
+}
+
+// deal starts a fresh word with full lives.
+func (h *hangman) deal() {
+	h.word = hangmanWords[rand.Intn(len(hangmanWords))]
+	h.guessed = make(map[byte]bool)
+	h.wrong = 0
+	h.won = false
+}
+
+// revealed reports whether every letter of the word has been guessed.
+func (h *hangman) revealed() bool {
+	for i := 0; i < len(h.word); i++ {
+		if !h.guessed[h.word[i]] {
+			return false
+		}
+	}
+	return true
+}
+
+func (h *hangman) Init() tea.Cmd { return nil }
+
+func (h *hangman) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	key, ok := msg.(tea.KeyMsg)
+	if !ok {
+		return h, nil
+	}
+	switch key.String() {
+	case "q", "esc":
+		return h, back
+	case "r":
+		if h.dead {
+			return newHangman(h.user, h.ctx), nil
+		}
+		return h, nil
+	case " ", "enter":
+		if h.won {
+			h.deal() // advance to the next word
+		}
+		return h, nil
+	}
+
+	if h.dead || h.won {
+		return h, nil
+	}
+
+	// A single letter is a guess.
+	s := key.String()
+	if len(s) != 1 {
+		return h, nil
+	}
+	c := s[0]
+	if c >= 'a' && c <= 'z' {
+		c -= 'a' - 'A'
+	}
+	if c < 'A' || c > 'Z' || h.guessed[c] {
+		return h, nil
+	}
+	h.guessed[c] = true
+
+	if strings.IndexByte(h.word, c) < 0 {
+		h.wrong++
+		if h.wrong >= hangmanMaxWrong {
+			h.dead = true
+			// Guests play, members persist (PRD §5.1).
+			if !h.saved && h.user.Kind != auth.Guest && h.user.StoreID > 0 && h.score > 0 {
+				_ = h.ctx.Store.AddScore(h.user.StoreID, "hangman", h.score)
+				h.saved = true
+			}
+		}
+		return h, nil
+	}
+
+	if h.revealed() {
+		h.won = true
+		h.solved++
+		// Longer words and unused guesses are worth more.
+		h.score += int64(len(h.word)*10 + (hangmanMaxWrong-h.wrong)*5)
+	}
+	return h, nil
+}
+
+// hangmanStages are the gallows ASCII for 0..6 wrong guesses.
+var hangmanStages = []string{
+	"  +---+\n      |\n      |\n      |\n     ===",
+	"  +---+\n  O   |\n      |\n      |\n     ===",
+	"  +---+\n  O   |\n  |   |\n      |\n     ===",
+	"  +---+\n  O   |\n /|   |\n      |\n     ===",
+	"  +---+\n  O   |\n /|\\  |\n      |\n     ===",
+	"  +---+\n  O   |\n /|\\  |\n /    |\n     ===",
+	"  +---+\n  O   |\n /|\\  |\n / \\  |\n     ===",
+}
+
+var (
+	hmWordStyle  = lipgloss.NewStyle().Foreground(lipgloss.Color("#fbbf24")).Bold(true)
+	hmWrongStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("203"))
+	hmGoodStyle  = lipgloss.NewStyle().Foreground(lipgloss.Color("#4ade80"))
+	hmGallows    = lipgloss.NewStyle().Foreground(lipgloss.Color("241"))
+)
+
+func (h *hangman) View() string {
+	out := fmt.Sprintf("Hangman — score %d · solved %d\n\n", h.score, h.solved)
+	out += hmGallows.Render(hangmanStages[h.wrong]) + "\n\n"
+
+	// Masked word: reveal the whole thing once the round is over.
+	var b strings.Builder
+	for i := 0; i < len(h.word); i++ {
+		if i > 0 {
+			b.WriteByte(' ')
+		}
+		if h.guessed[h.word[i]] || h.dead {
+			b.WriteByte(h.word[i])
+		} else {
+			b.WriteByte('_')
+		}
+	}
+	out += hmWordStyle.Render(b.String()) + "\n\n"
+
+	// Wrong letters tried.
+	var wrong []string
+	for c := byte('A'); c <= 'Z'; c++ {
+		if h.guessed[c] && strings.IndexByte(h.word, c) < 0 {
+			wrong = append(wrong, string(c))
+		}
+	}
+	out += fmt.Sprintf("misses (%d/%d): ", h.wrong, hangmanMaxWrong)
+	if len(wrong) > 0 {
+		out += hmWrongStyle.Render(strings.Join(wrong, " "))
+	} else {
+		out += hmGallows.Render("—")
+	}
+	out += "\n\n"
+
+	switch {
+	case h.dead:
+		out += hmWrongStyle.Render("☠  out of guesses — the word was "+h.word) + "\n"
+		out += "r restart · q back"
+	case h.won:
+		out += hmGoodStyle.Render("✓  solved!") + "  space next word · q back"
+	default:
+		out += "guess a letter · q back"
+	}
+	return lipgloss.NewStyle().Padding(1, 2).Render(out)
+}

plugins/arcade/hangman_test.go

@@ -0,0 +1,86 @@
+package arcade
+
+import (
+	"testing"
+
+	tea "github.com/charmbracelet/bubbletea"
+
+	"github.com/profullstack/agentbbs/internal/auth"
+	"github.com/profullstack/agentbbs/internal/plugin"
+)
+
+// key builds a single-rune key press the way bubbletea delivers it.
+func key(r rune) tea.KeyMsg { return tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{r}} }
+
+// guest avoids the store path (only members persist), so ctx.Store can be nil.
+func newTestHangman(word string) *hangman {
+	h := newHangman(auth.User{Kind: auth.Guest}, plugin.Context{})
+	h.word = word
+	h.guessed = make(map[byte]bool)
+	h.wrong = 0
+	h.won = false
+	return h
+}
+
+func TestHangmanSolveScores(t *testing.T) {
+	h := newTestHangman("CAT")
+	for _, r := range "CAT" {
+		m, _ := h.Update(key(r))
+		h = m.(*hangman)
+	}
+	if !h.won {
+		t.Fatalf("expected won after guessing every letter")
+	}
+	if h.solved != 1 {
+		t.Fatalf("solved = %d, want 1", h.solved)
+	}
+	// len 3 *10 + (6-0)*5 = 60.
+	if h.score != 60 {
+		t.Fatalf("score = %d, want 60", h.score)
+	}
+	if h.dead {
+		t.Fatalf("should not be dead after a solve")
+	}
+}
+
+func TestHangmanWrongGuessIsCountedOnce(t *testing.T) {
+	h := newTestHangman("CAT")
+	for i := 0; i < 3; i++ { // repeat the same wrong letter
+		m, _ := h.Update(key('Z'))
+		h = m.(*hangman)
+	}
+	if h.wrong != 1 {
+		t.Fatalf("wrong = %d, want 1 (repeat guesses must not stack)", h.wrong)
+	}
+}
+
+func TestHangmanDeathAfterSixMisses(t *testing.T) {
+	h := newTestHangman("CAT")
+	for _, r := range "BDEFGH" { // six letters absent from CAT
+		m, _ := h.Update(key(r))
+		h = m.(*hangman)
+	}
+	if h.wrong != hangmanMaxWrong {
+		t.Fatalf("wrong = %d, want %d", h.wrong, hangmanMaxWrong)
+	}
+	if !h.dead {
+		t.Fatalf("expected dead after %d misses", hangmanMaxWrong)
+	}
+}
+
+func TestHangmanLowercaseInputAndAdvance(t *testing.T) {
+	h := newTestHangman("CAT")
+	for _, r := range "cat" { // lowercase should still solve
+		m, _ := h.Update(key(r))
+		h = m.(*hangman)
+	}
+	if !h.won {
+		t.Fatalf("lowercase input should solve the word")
+	}
+	// space deals a fresh word and clears the round flags.
+	m, _ := h.Update(tea.KeyMsg{Type: tea.KeySpace})
+	h = m.(*hangman)
+	if h.won || h.wrong != 0 || len(h.guessed) != 0 {
+		t.Fatalf("space should deal a fresh round: won=%v wrong=%d guessed=%d", h.won, h.wrong, len(h.guessed))
+	}
+}