Add support for up to 6 players.

internal/server/bots.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"errors"
+	"fmt"
 	"log/slog"
 	"math/rand/v2"
 	"time"
@@ -10,19 +11,23 @@ import (
 	"github.com/greyson/super-auto-pets-board-game/internal/game"
 )
 
-// botDifficulty maps the API's difficulty names to a skill level and a
-// table name for the bot. The levels are calibrated against a competent
-// player (ai.competentLevel, ~0.60): easy loses ~95% of games to them, medium
-// is an even match, and hard wins ~80% (see TestDiagWinRateCurve). Medium is
-// pinned to the competent level itself; hard is the strongest bot the engine
-// can field.
+// botDifficulty maps the API's difficulty names to a skill level and a pool of
+// table names. The levels are calibrated against a competent player
+// (ai.competentLevel, ~0.60): easy loses ~95% of games to them, medium is an
+// even match, and hard wins ~80% (see TestDiagWinRateCurve). Medium is pinned
+// to the competent level itself; hard is the strongest bot the engine can
+// field.
+//
+// A table can hold up to five bots, so each difficulty carries a list of names
+// rather than one: the first unused name is taken, keeping every seat
+// distinguishable while the name still hints at how hard it plays.
 var botDifficulty = map[string]struct {
 	level float64
-	name  string
+	names []string
 }{
-	"easy":   {0.25, "Robo Rookie"},
-	"medium": {0.60, "Robo Rival"},
-	"hard":   {1.00, "Robo Ace"},
+	"easy":   {0.25, []string{"Robo Rookie", "Bitsy", "Clunk", "Pip", "Sprocket"}},
+	"medium": {0.60, []string{"Robo Rival", "Gizmo", "Widget", "Rusty", "Cogsworth"}},
+	"hard":   {1.00, []string{"Robo Ace", "Vex", "Apex", "Onyx", "Zenith"}},
 }
 
 // requireHost authorizes a lobby-management action: only the host (seat 0)
@@ -36,17 +41,37 @@ func requireHost(g *game.Game, playerID string) error {
 }
 
 // addBot seats a computer opponent for a difficulty name, translating the
-// name to the engine's skill level. Capacity and phase are enforced by the
-// engine's AddPlayer.
+// name to the engine's skill level and giving it a name nobody at the table is
+// already using. Capacity and phase are enforced by the engine's AddPlayer.
 func addBot(g *game.Game, difficulty string) error {
 	bot, ok := botDifficulty[difficulty]
 	if !ok {
 		return errors.New("unknown bot difficulty")
 	}
-	_, err := g.AddBot(bot.name, bot.level)
+	_, err := g.AddBot(botName(g, bot.names), bot.level)
 	return err
 }
 
+// botName picks the first name in the pool that no seat has taken. If a host
+// somehow exhausts the pool, it falls back to numbering the first name.
+func botName(g *game.Game, pool []string) string {
+	taken := make(map[string]bool, len(g.Players))
+	for _, p := range g.Players {
+		taken[p.Name] = true
+	}
+	for _, name := range pool {
+		if !taken[name] {
+			return name
+		}
+	}
+	for n := 2; ; n++ {
+		name := fmt.Sprintf("%s %d", pool[0], n)
+		if !taken[name] {
+			return name
+		}
+	}
+}
+
 // commitLocked is the one path every game mutation goes through: bots update
 // their memories from the new public state, the game is persisted, every
 // client gets its view, and the next bot move (if any) is scheduled. Callers