Replace polling loop with NATS pub/sub for game updates

Use via's embedded NATS server to notify players of state changes
instead of a 100ms polling ticker. Each player subscribes to
"game.<id>" on page load; via auto-cleans subscriptions on disconnect,
eliminating the need for manual player tracking and RegisterSync.

.gitignore

@@ -1,2 +1,3 @@
 c4
 c4.db
+data/

game/store.go

@@ -4,16 +4,14 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"sync"
-	"time"
 )
 
-type Syncable interface {
+type PubSub interface {
-	Sync()
+	Publish(subject string, data []byte) error
 }
 
 type PlayerSession struct {
 	Player *Player
-	Sync   Syncable
 }
 
 type Persister interface {
@@ -28,6 +26,7 @@ type GameStore struct {
 	games     map[string]*GameInstance
 	gamesMu   sync.RWMutex
 	persister Persister
+	pubsub    PubSub
 }
 
 func NewGameStore() *GameStore {
@@ -40,10 +39,23 @@ func (gs *GameStore) SetPersister(p Persister) {
 	gs.persister = p
 }
 
+func (gs *GameStore) SetPubSub(ps PubSub) {
+	gs.pubsub = ps
+}
+
+func (gs *GameStore) makeNotify(gameID string) func() {
+	return func() {
+		if gs.pubsub != nil {
+			gs.pubsub.Publish("game."+gameID, nil)
+		}
+	}
+}
+
 func (gs *GameStore) Create() *GameInstance {
 	id := GenerateID(4)
 	gi := NewGameInstance(id)
 	gi.persister = gs.persister
+	gi.notify = gs.makeNotify(id)
 	gs.gamesMu.Lock()
 	gs.games[id] = gi
 	gs.gamesMu.Unlock()
@@ -52,7 +64,6 @@ func (gs *GameStore) Create() *GameInstance {
 		gs.persister.SaveGame(gi.game)
 	}
 
-	go gi.run()
 	return gi
 }
 
@@ -65,7 +76,6 @@ func (gs *GameStore) Get(id string) (*GameInstance, bool) {
 		return gi, true
 	}
 
-	// Try to load from database
 	if gs.persister == nil {
 		return nil, false
 	}
@@ -86,27 +96,20 @@ func (gs *GameStore) Get(id string) (*GameInstance, bool) {
 
 	gi = &GameInstance{
 		game:      game,
-		players:   make(map[PlayerID]Syncable),
-		leave:     make(chan PlayerID, 5),
-		done:      make(chan struct{}),
 		persister: gs.persister,
+		notify:    gs.makeNotify(id),
 	}
 
 	gs.gamesMu.Lock()
 	gs.games[id] = gi
 	gs.gamesMu.Unlock()
 
-	go gi.run()
 	return gi, true
 }
 
 func (gs *GameStore) Delete(id string) error {
 	gs.gamesMu.Lock()
-	gi, ok := gs.games[id]
+	delete(gs.games, id)
-	if ok {
-		delete(gs.games, id)
-		close(gi.done)
-	}
 	gs.gamesMu.Unlock()
 
 	if gs.persister != nil {
@@ -124,20 +127,14 @@ func GenerateID(size int) string {
 type GameInstance struct {
 	game      *Game
 	gameMu    sync.RWMutex
-	players   map[PlayerID]Syncable
+	notify    func()
-	playersMu sync.RWMutex
-	leave     chan PlayerID
-	done      chan struct{}
-	dirty     bool
 	persister Persister
 }
 
 func NewGameInstance(id string) *GameInstance {
 	return &GameInstance{
-		game:    NewGame(id),
+		game:   NewGame(id),
-		players: make(map[PlayerID]Syncable),
+		notify: func() {},
-		leave:   make(chan PlayerID, 5),
-		done:    make(chan struct{}),
 	}
 }
 
@@ -152,30 +149,25 @@ func (gi *GameInstance) Join(ps *PlayerSession) bool {
 	defer gi.gameMu.Unlock()
 
 	var slot int
-	// Assign player to an open slot
 	if gi.game.Players[0] == nil {
-		ps.Player.Color = 1 // Red
+		ps.Player.Color = 1
 		gi.game.Players[0] = ps.Player
 		slot = 0
 	} else if gi.game.Players[1] == nil {
-		ps.Player.Color = 2 // Yellow
+		ps.Player.Color = 2
 		gi.game.Players[1] = ps.Player
 		gi.game.Status = StatusInProgress
 		slot = 1
 	} else {
-		return false // Game is full
+		return false
 	}
 
-	gi.playersMu.Lock()
-	gi.players[ps.Player.ID] = ps.Sync
-	gi.playersMu.Unlock()
-
 	if gi.persister != nil {
 		gi.persister.SaveGamePlayer(gi.game.ID, ps.Player, slot)
 		gi.persister.SaveGame(gi.game)
 	}
 
-	gi.dirty = true
+	gi.notify()
 	return true
 }
 
@@ -196,13 +188,6 @@ func (gi *GameInstance) GetPlayerColor(pid PlayerID) int {
 	return 0
 }
 
-func (gi *GameInstance) RegisterSync(playerID PlayerID, sync Syncable) {
-	gi.playersMu.Lock()
-	gi.players[playerID] = sync
-	gi.playersMu.Unlock()
-	gi.dirty = true
-}
-
 func (gi *GameInstance) CreateRematch(gs *GameStore) *GameInstance {
 	gi.gameMu.Lock()
 	defer gi.gameMu.Unlock()
@@ -223,7 +208,7 @@ func (gi *GameInstance) CreateRematch(gs *GameStore) *GameInstance {
 		}
 	}
 
-	gi.dirty = true
+	gi.notify()
 	return newGI
 }
 
@@ -253,45 +238,6 @@ func (gi *GameInstance) DropPiece(col int, playerColor int) bool {
 		gi.persister.SaveGame(gi.game)
 	}
 
-	gi.dirty = true
+	gi.notify()
 	return true
 }
-
-func (gi *GameInstance) run() {
-	ticker := time.NewTicker(100 * time.Millisecond)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case pid := <-gi.leave:
-			gi.playersMu.Lock()
-			delete(gi.players, pid)
-			gi.playersMu.Unlock()
-		case <-ticker.C:
-			gi.publish()
-		case <-gi.done:
-			return
-		}
-	}
-}
-
-func (gi *GameInstance) publish() {
-	gi.gameMu.Lock()
-	if !gi.dirty {
-		gi.gameMu.Unlock()
-		return
-	}
-	gi.dirty = false
-
-	gi.playersMu.RLock()
-	syncers := make([]Syncable, 0, len(gi.players))
-	for _, sync := range gi.players {
-		syncers = append(syncers, sync)
-	}
-	gi.playersMu.RUnlock()
-	gi.gameMu.Unlock()
-
-	for _, sync := range syncers {
-		sync.Sync()
-	}
-}

go.mod

@@ -15,12 +15,22 @@ require (
 	github.com/alexedwards/scs/sqlite3store v0.0.0-20251002162104-209de6e426de // indirect
 	github.com/alexedwards/scs/v2 v2.9.0 // indirect
 	github.com/andybalholm/brotli v1.2.0 // indirect
+	github.com/antithesishq/antithesis-sdk-go v0.5.0 // indirect
+	github.com/cenkalti/backoff v2.2.1+incompatible // indirect
+	github.com/delaneyj/toolbelt v0.9.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/go-tpm v0.9.7 // indirect
 	github.com/hookenz/gotailwind/v4 v4.1.18 // indirect
 	github.com/klauspost/compress v1.18.2 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mfridman/interpolate v0.0.2 // indirect
+	github.com/minio/highwayhash v1.0.4-0.20251030100505-070ab1a87a76 // indirect
+	github.com/nats-io/jwt/v2 v2.8.0 // indirect
+	github.com/nats-io/nats-server/v2 v2.12.2 // indirect
+	github.com/nats-io/nats.go v1.48.0 // indirect
+	github.com/nats-io/nkeys v0.4.12 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/ncruces/go-strftime v1.0.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/rs/zerolog v1.34.0 // indirect
@@ -28,9 +38,10 @@ require (
 	github.com/starfederation/datastar-go v1.0.3 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 // indirect
+	golang.org/x/exp v0.0.0-20251125195548-87e1e737ad39 // indirect
-	golang.org/x/sync v0.17.0 // indirect
+	golang.org/x/sync v0.18.0 // indirect
 	golang.org/x/sys v0.40.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
 	maragu.dev/gomponents v1.2.0 // indirect
 	modernc.org/libc v1.67.4 // indirect
 	modernc.org/mathutil v1.7.1 // indirect

go.sum

@@ -7,16 +7,24 @@ github.com/alexedwards/scs/v2 v2.9.0/go.mod h1:ToaROZxyKukJKT/xLcVQAChi5k6+Pn1Gv
 github.com/andybalholm/brotli v1.0.5/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
 github.com/andybalholm/brotli v1.2.0 h1:ukwgCxwYrmACq68yiUqwIWnGY0cTPox/M94sVwToPjQ=
 github.com/andybalholm/brotli v1.2.0/go.mod h1:rzTDkvFWvIrjDXZHkuS16NPggd91W3kUSvPlQ1pLaKY=
+github.com/antithesishq/antithesis-sdk-go v0.5.0 h1:cudCFF83pDDANcXFzkQPUHHedfnnIbUO3JMr9fqwFJs=
+github.com/antithesishq/antithesis-sdk-go v0.5.0/go.mod h1:IUpT2DPAKh6i/YhSbt6Gl3v2yvUZjmKncl7U91fup7E=
+github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
+github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/delaneyj/toolbelt v0.9.1 h1:QJComn2qoaQ4azl5uRkGpdHSO9e+JtoxDTXCiQHvH8o=
+github.com/delaneyj/toolbelt v0.9.1/go.mod h1:eNXpPuThjTD4tpRNCBl4JEz9jdg9LpyzNuyG+stnIbs=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/google/brotli/go/cbrotli v0.0.0-20230829110029-ed738e842d2f h1:jopqB+UTSdJGEJT8tEqYyE29zN91fi2827oLET8tl7k=
 github.com/google/brotli/go/cbrotli v0.0.0-20230829110029-ed738e842d2f/go.mod h1:nOPhAkwVliJdNTkj3gXpljmWhjc4wCaVqbMJcPKWP4s=
+github.com/google/go-tpm v0.9.7 h1:u89J4tUUeDTlH8xxC3CTW7OHZjbjKoHdQ9W7gCUhtxA=
+github.com/google/go-tpm v0.9.7/go.mod h1:h9jEsEECg7gtLis0upRBQU+GhYVH6jMjrFxI8u6bVUY=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -40,6 +48,18 @@ github.com/mattn/go-sqlite3 v1.14.32 h1:JD12Ag3oLy1zQA+BNn74xRgaBbdhbNIDYvQUEuuE
 github.com/mattn/go-sqlite3 v1.14.32/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
 github.com/mfridman/interpolate v0.0.2 h1:pnuTK7MQIxxFz1Gr+rjSIx9u7qVjf5VOoM/u6BbAxPY=
 github.com/mfridman/interpolate v0.0.2/go.mod h1:p+7uk6oE07mpE/Ik1b8EckO0O4ZXiGAfshKBWLUM9Xg=
+github.com/minio/highwayhash v1.0.4-0.20251030100505-070ab1a87a76 h1:KGuD/pM2JpL9FAYvBrnBBeENKZNh6eNtjqytV6TYjnk=
+github.com/minio/highwayhash v1.0.4-0.20251030100505-070ab1a87a76/go.mod h1:GGYsuwP/fPD6Y9hMiXuapVvlIUEhFhMTh0rxU3ik1LQ=
+github.com/nats-io/jwt/v2 v2.8.0 h1:K7uzyz50+yGZDO5o772eRE7atlcSEENpL7P+b74JV1g=
+github.com/nats-io/jwt/v2 v2.8.0/go.mod h1:me11pOkwObtcBNR8AiMrUbtVOUGkqYjMQZ6jnSdVUIA=
+github.com/nats-io/nats-server/v2 v2.12.2 h1:4TEQd0Y4zvcW0IsVxjlXnRso1hBkQl3TS0BI+SxgPhE=
+github.com/nats-io/nats-server/v2 v2.12.2/go.mod h1:j1AAttYeu7WnvD8HLJ+WWKNMSyxsqmZ160pNtCQRMyE=
+github.com/nats-io/nats.go v1.48.0 h1:pSFyXApG+yWU/TgbKCjmm5K4wrHu86231/w84qRVR+U=
+github.com/nats-io/nats.go v1.48.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
+github.com/nats-io/nkeys v0.4.12 h1:nssm7JKOG9/x4J8II47VWCL1Ds29avyiQDRn0ckMvDc=
+github.com/nats-io/nkeys v0.4.12/go.mod h1:MT59A1HYcjIcyQDJStTfaOY6vhy9XTUjOFo+SVsvpBg=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
 github.com/ncruces/go-strftime v1.0.0 h1:HMFp8mLCTPp341M/ZnA4qaf7ZlsbTc+miZjCLOFAw7w=
 github.com/ncruces/go-strftime v1.0.0/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
 github.com/pierrec/lz4/v4 v4.1.18/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
@@ -81,19 +101,22 @@ go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
 go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
 golang.org/x/crypto v0.47.0 h1:V6e3FRj+n4dbpw86FJ8Fv7XVOql7TEwpHapKoMJ/GO8=
 golang.org/x/crypto v0.47.0/go.mod h1:ff3Y9VzzKbwSSEzWqJsJVBnWmRwRSHt/6Op5n9bQc4A=
-golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 h1:mgKeJMpvi0yx/sU5GsxQ7p6s2wtOnGAHZWCHUM4KGzY=
+golang.org/x/exp v0.0.0-20251125195548-87e1e737ad39 h1:DHNhtq3sNNzrvduZZIiFyXWOL9IWaDPHqTnLJp+rCBY=
-golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546/go.mod h1:j/pmGrbnkbPtQfxEe5D0VQhZC6qKbfKifgD0oM7sR70=
+golang.org/x/exp v0.0.0-20251125195548-87e1e737ad39/go.mod h1:46edojNIoXTNOhySWIWdix628clX9ODXwPsQuG6hsK0=
-golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
+golang.org/x/mod v0.30.0 h1:fDEXFVZ/fmCKProc/yAXXUijritrDzahmwwefnjoPFk=
-golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
+golang.org/x/mod v0.30.0/go.mod h1:lAsf5O2EvJeSFMiBxXDki7sCgAxEUcZHXoXMKT4GJKc=
-golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
+golang.org/x/sync v0.18.0 h1:kr88TuHDroi+UVf+0hZnirlk8o8T+4MrK6mr60WkH/I=
-golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sync v0.18.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
 golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
-golang.org/x/tools v0.38.0 h1:Hx2Xv8hISq8Lm16jvBZ2VQf+RLmbd7wVUsALibYI/IQ=
+golang.org/x/time v0.14.0 h1:MRx4UaLrDotUKUdCIqzPC48t1Y9hANFKIRpNx+Te8PI=
-golang.org/x/tools v0.38.0/go.mod h1:yEsQ/d/YK8cjh0L6rZlY8tgtlKiBNTL14pGDJPJpYQs=
+golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
+golang.org/x/tools v0.39.0 h1:ik4ho21kwuQln40uelmciQPp9SipgNDdrafrYA4TmQQ=
+golang.org/x/tools v0.39.0/go.mod h1:JnefbkDPyD8UU2kI5fuf8ZX4/yUeh9W877ZeBONxUqQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

main.go

@@ -15,6 +15,7 @@ import (
 	"github.com/ryanhamamura/c4/ui"
 	"github.com/ryanhamamura/via"
 	"github.com/ryanhamamura/via/h"
+	"github.com/ryanhamamura/via/vianats"
 )
 
 var store = game.NewGameStore()
@@ -43,12 +44,20 @@ func main() {
 		log.Fatal(err)
 	}
 
+	ctx := context.Background()
+	ns, err := vianats.New(ctx, "./data/nats")
+	if err != nil {
+		log.Fatal(err)
+	}
+	store.SetPubSub(ns)
+
 	v := via.New()
 	v.Config(via.Options{
 		LogLevel:       via.LogLevelDebug,
 		DocumentTitle:  "Connect 4",
 		ServerAddress:  ":7331",
 		SessionManager: sessionManager,
+		PubSub:         ns,
 		Plugins:        []via.Plugin{DaisyUIPlugin},
 	})
 
@@ -307,7 +316,6 @@ func main() {
 				}
 				gi.Join(&game.PlayerSession{
 					Player: player,
-					Sync:   c,
 				})
 			}
 			c.Sync()
@@ -336,6 +344,11 @@ func main() {
 			}
 		})
 
+		// Subscribe to game updates so the opponent's moves trigger a re-render
+		if gameExists {
+			c.Subscribe("game."+gameID, func(data []byte) { c.Sync() })
+		}
+
 		// If nickname exists in session and game exists, join immediately
 		if gameExists && sessionNickname != "" && gi.GetPlayerColor(playerID) == 0 {
 			player := &game.Player{
@@ -347,11 +360,7 @@ func main() {
 			}
 			gi.Join(&game.PlayerSession{
 				Player: player,
-				Sync:   c,
 			})
-		} else if gameExists && gi.GetPlayerColor(playerID) != 0 {
-			// Re-register sync context for existing players on reconnect
-			gi.RegisterSync(playerID, c)
 		}
 
 		c.View(func() h.H {