feat: add generic pub/sub helpers and pubsub-crud example

Add typed Publish[T] and Subscribe[T] generic helpers that handle
JSON marshaling, along with vianats.EnsureStream and ReplayHistory
helpers. Refactor nats-chatroom to use the new APIs.

Add pubsub-crud example demonstrating CRUD operations with DaisyUI
toast notifications broadcast to all connected clients via NATS.

.gitignore

@@ -47,3 +47,7 @@ internal/examples/picocss/picocss
 internal/examples/plugins/plugins
 internal/examples/realtimechart/realtimechart
 internal/examples/shakespeare/shakespeare
+internal/examples/nats-chatroom/nats-chatroom
+
+# NATS data directory
+data/

actiontrigger.go

@@ -21,6 +21,8 @@ type triggerOpts struct {
 	hasSignal      bool
 	signalID       string
 	value          string
+	window         bool
+	preventDefault bool
 }
 
 type withSignalOpt struct {
@@ -34,6 +36,28 @@ func (o withSignalOpt) apply(opts *triggerOpts) {
 	opts.value = o.value
 }
 
+type withWindowOpt struct{}
+
+func (o withWindowOpt) apply(opts *triggerOpts) {
+	opts.window = true
+}
+
+// WithWindow makes the event listener attach to the window instead of the element.
+func WithWindow() ActionTriggerOption {
+	return withWindowOpt{}
+}
+
+type withPreventDefaultOpt struct{}
+
+func (o withPreventDefaultOpt) apply(opts *triggerOpts) {
+	opts.preventDefault = true
+}
+
+// WithPreventDefault calls evt.preventDefault() for matched keys.
+func WithPreventDefault() ActionTriggerOption {
+	return withPreventDefaultOpt{}
+}
+
 // WithSignal sets a signal value before triggering the action.
 func WithSignal(sig *signal, value string) ActionTriggerOption {
 	return withSignalOpt{
@@ -54,7 +78,7 @@ func buildOnExpr(base string, opts *triggerOpts) string {
 	if !opts.hasSignal {
 		return base
 	}
-	return fmt.Sprintf("$%s=%s;%s", opts.signalID, opts.value, base)
+	return fmt.Sprintf("$%s=%s,%s", opts.signalID, opts.value, base)
 }
 
 func applyOptions(options ...ActionTriggerOption) triggerOpts {
@@ -92,5 +116,49 @@ func (a *actionTrigger) OnKeyDown(key string, options ...ActionTriggerOption) h.
 	if key != "" {
 		condition = fmt.Sprintf("evt.key==='%s' &&", key)
 	}
-	return h.Data("on:keydown", fmt.Sprintf("%s%s", condition, buildOnExpr(actionURL(a.id), &opts)))
+	attrName := "on:keydown"
+	if opts.window {
+		attrName = "on:keydown__window"
+	}
+	return h.Data(attrName, fmt.Sprintf("%s%s", condition, buildOnExpr(actionURL(a.id), &opts)))
+}
+
+// KeyBinding pairs a key with an action and per-binding options.
+type KeyBinding struct {
+	Key     string
+	Action  *actionTrigger
+	Options []ActionTriggerOption
+}
+
+// KeyBind creates a KeyBinding for use with OnKeyDownMap.
+func KeyBind(key string, action *actionTrigger, options ...ActionTriggerOption) KeyBinding {
+	return KeyBinding{Key: key, Action: action, Options: options}
+}
+
+// OnKeyDownMap produces a single window-scoped keydown attribute that dispatches
+// to different actions based on the pressed key. Each binding can reference a
+// different action and carry its own signal/preventDefault options.
+func OnKeyDownMap(bindings ...KeyBinding) h.H {
+	if len(bindings) == 0 {
+		return nil
+	}
+
+	expr := ""
+	for i, b := range bindings {
+		opts := applyOptions(b.Options...)
+
+		branch := ""
+		if opts.preventDefault {
+			branch = "evt.preventDefault(),"
+		}
+		branch += buildOnExpr(actionURL(b.Action.id), &opts)
+
+		if i > 0 {
+			expr += " : "
+		}
+		expr += fmt.Sprintf("evt.key==='%s' ? (%s)", b.Key, branch)
+	}
+	expr += " : void 0"
+
+	return h.Data("on:keydown__window", expr)
 }

configuration.go

@@ -1,15 +1,17 @@
 package via
 
-import "github.com/alexedwards/scs/v2"
+import (
+	"github.com/alexedwards/scs/v2"
+	"github.com/rs/zerolog"
+)
 
-type LogLevel int
+func ptr(l zerolog.Level) *zerolog.Level { return &l }
 
-const (
+var (
-	undefined LogLevel = iota
+	LogLevelDebug = ptr(zerolog.DebugLevel)
-	LogLevelError
+	LogLevelInfo  = ptr(zerolog.InfoLevel)
-	LogLevelWarn
+	LogLevelWarn  = ptr(zerolog.WarnLevel)
-	LogLevelInfo
+	LogLevelError = ptr(zerolog.ErrorLevel)
-	LogLevelDebug
 )
 
 // Plugin is a func that can mutate the given *via.V app runtime. It is useful to integrate popular JS/CSS UI libraries or tools.
@@ -23,9 +25,12 @@ type Options struct {
 	// The http server address. e.g. ':3000'
 	ServerAddress string
 
-	// Level of the logs to write to stdout.
+	// LogLevel sets the minimum log level. nil keeps the default (Info).
-	// Options: Error, Warn, Info, Debug.
+	LogLevel *zerolog.Level
-	LogLvl LogLevel
+
+	// Logger overrides the default logger entirely. When set, LogLevel and
+	// DevMode have no effect on logging.
+	Logger *zerolog.Logger
 
 	// The title of the HTML document.
 	DocumentTitle string
@@ -45,4 +50,8 @@ type Options struct {
 	// DatastarPath is the URL path where the script is served.
 	// Defaults to "/_datastar.js" if empty.
 	DatastarPath string
+
+	// PubSub enables publish/subscribe messaging. Use vianats.New() for an
+	// embedded NATS backend, or supply any PubSub implementation.
+	PubSub PubSub
 }

context.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"log"
 	"maps"
 	"reflect"
 	"sync"
@@ -31,6 +30,9 @@ type Context struct {
 	mu                sync.RWMutex
 	ctxDisposedChan   chan struct{}
 	reqCtx            context.Context
+	subscriptions     []Subscription
+	subsMu            sync.Mutex
+	disposeOnce       sync.Once
 }
 
 // View defines the UI rendered by this context.
@@ -349,11 +351,23 @@ func (c *Context) ReplaceURLf(format string, a ...any) {
 	c.ReplaceURL(fmt.Sprintf(format, a...))
 }
 
-// stopAllRoutines stops all go routines tied to this Context preventing goroutine leaks.
+// dispose idempotently tears down this context: unsubscribes all pubsub
+// subscriptions and closes ctxDisposedChan to stop routines and exit the SSE loop.
+func (c *Context) dispose() {
+	c.disposeOnce.Do(func() {
+		c.unsubscribeAll()
+		c.stopAllRoutines()
+	})
+}
+
+// stopAllRoutines closes ctxDisposedChan, broadcasting to all listening
+// goroutines (OnIntervalRoutine, SSE loop) that this context is done.
 func (c *Context) stopAllRoutines() {
 	select {
-	case c.ctxDisposedChan <- struct{}{}:
+	case <-c.ctxDisposedChan:
+		// already closed
 	default:
+		close(c.ctxDisposedChan)
 	}
 }
 
@@ -403,9 +417,58 @@ func (c *Context) Session() *Session {
 	}
 }
 
+// Publish sends data to the given subject via the configured PubSub backend.
+// Returns an error if no PubSub is configured. No-ops during panic-check init.
+func (c *Context) Publish(subject string, data []byte) error {
+	if c.id == "" {
+		return nil
+	}
+	if c.app.pubsub == nil {
+		return fmt.Errorf("pubsub not configured")
+	}
+	return c.app.pubsub.Publish(subject, data)
+}
+
+// Subscribe creates a subscription on the configured PubSub backend.
+// The subscription is tracked for automatic cleanup when the context is disposed.
+// Returns an error if no PubSub is configured. No-ops during panic-check init.
+func (c *Context) Subscribe(subject string, handler func(data []byte)) (Subscription, error) {
+	if c.id == "" {
+		return nil, nil
+	}
+	if c.app.pubsub == nil {
+		return nil, fmt.Errorf("pubsub not configured")
+	}
+	sub, err := c.app.pubsub.Subscribe(subject, handler)
+	if err != nil {
+		return nil, err
+	}
+
+	// Track on page context for cleanup (components use parent, like signals/actions)
+	target := c
+	if c.isComponent() {
+		target = c.parentPageCtx
+	}
+	target.subsMu.Lock()
+	target.subscriptions = append(target.subscriptions, sub)
+	target.subsMu.Unlock()
+	return sub, nil
+}
+
+// unsubscribeAll cleans up all tracked subscriptions for this context and its components.
+func (c *Context) unsubscribeAll() {
+	c.subsMu.Lock()
+	subs := c.subscriptions
+	c.subscriptions = nil
+	c.subsMu.Unlock()
+	for _, sub := range subs {
+		sub.Unsubscribe()
+	}
+}
+
 func newContext(id string, route string, v *V) *Context {
 	if v == nil {
-		log.Fatal("create context failed: app pointer is nil")
+		panic("create context failed: app pointer is nil")
 	}
 
 	return &Context{

go.mod

@@ -8,17 +8,35 @@ require (
 	github.com/DATA-DOG/go-sqlmock v1.5.2
 	github.com/alexedwards/scs/sqlite3store v0.0.0-20251002162104-209de6e426de
 	github.com/alexedwards/scs/v2 v2.9.0
+	github.com/delaneyj/toolbelt v0.9.1
 	github.com/mattn/go-sqlite3 v1.14.32
+	github.com/nats-io/nats.go v1.48.0
+	github.com/rs/zerolog v1.34.0
 	github.com/starfederation/datastar-go v1.0.3
-	github.com/stretchr/testify v1.10.0
+	github.com/stretchr/testify v1.11.1
 )
 
 require (
 	github.com/CAFxX/httpcompression v0.0.9 // indirect
 	github.com/andybalholm/brotli v1.2.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/antithesishq/antithesis-sdk-go v0.5.0 // indirect
-	github.com/klauspost/compress v1.18.0 // indirect
+	github.com/cenkalti/backoff v2.2.1+incompatible // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/google/go-tpm v0.9.7 // indirect
+	github.com/klauspost/compress v1.18.2 // indirect
+	github.com/kr/text v0.2.0 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // 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/nkeys v0.4.12 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
+	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
+	golang.org/x/crypto v0.45.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -9,23 +9,64 @@ 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/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 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/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/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
 github.com/klauspost/compress v1.16.7/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
-github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
+github.com/klauspost/compress v1.18.2 h1:iiPHWW0YrcFgpBYhsA6D1+fqHssJscY/Tm/y2Uqnapk=
-github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
+github.com/klauspost/compress v1.18.2/go.mod h1:R0h/fSBs8DE4ENlcrlib3PsXS61voFxhIs2DeRhCvJ4=
 github.com/klauspost/pgzip v1.2.6/go.mod h1:Ch1tH69qFZu15pkjo5kYi6mth2Zzwzt50oCQKQE9RUs=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
+github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-sqlite3 v1.14.6/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
 github.com/mattn/go-sqlite3 v1.14.32 h1:JD12Ag3oLy1zQA+BNn74xRgaBbdhbNIDYvQUEuuErjs=
 github.com/mattn/go-sqlite3 v1.14.32/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
+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/pierrec/lz4/v4 v4.1.18 h1:xaKrnTkyoqfh1YItXl56+6KJNVYWlEEPuAQW9xsplYQ=
 github.com/pierrec/lz4/v4 v4.1.18/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
+github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
+github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
+github.com/rs/xid v1.6.0/go.mod h1:7XoLgs4eV+QndskICGsho+ADou8ySMSjJKDIan90Nz0=
+github.com/rs/zerolog v1.34.0 h1:k43nTLIwcTVQAncfCw4KZ2VY6ukYoZaBPNOE8txlOeY=
+github.com/rs/zerolog v1.34.0/go.mod h1:bJsvje4Z08ROH4Nhs5iH600c3IkWhwp44iRc54W6wYQ=
 github.com/starfederation/datastar-go v1.0.3 h1:DnzgsJ6tDHDM6y5Nxsk0AGW/m8SyKch2vQg3P1xGTcU=
 github.com/starfederation/datastar-go v1.0.3/go.mod h1:stm83LQkhZkwa5GzzdPEN6dLuu8FVwxIv0w1DYkbD3w=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -34,8 +75,8 @@ github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpE
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
-github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/ulikunitz/xz v0.5.11/go.mod h1:nbz6k7qbPmH4IRqmfOplQw/tblSgqTqBwxkY0oWt/14=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
@@ -43,8 +84,19 @@ github.com/valyala/gozstd v1.20.1 h1:xPnnnvjmaDDitMFfDxmQ4vpx0+3CdTg2o3lALvXTU/g
 github.com/valyala/gozstd v1.20.1/go.mod h1:y5Ew47GLlP37EkTB+B4s7r6A5rdaeB7ftbl9zoYiIPQ=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+golang.org/x/crypto v0.45.0 h1:jMBrvKuj23MTlT0bQEOBcAE0mjg8mK9RXFhRH6nyF3Q=
+golang.org/x/crypto v0.45.0/go.mod h1:XTGrrkGJve7CYK7J8PEww4aY7gM3qMCElcJQ8n8JdX4=
+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 v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
+golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/time v0.14.0 h1:MRx4UaLrDotUKUdCIqzPC48t1Y9hANFKIRpNx+Te8PI=
+golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 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=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/examples/chatroom/main.go

@@ -22,7 +22,7 @@ func main() {
 	v.Config(via.Options{
 		DevMode:       true,
 		DocumentTitle: "ViaChat",
-		LogLvl:        via.LogLevelInfo,
+		LogLevel:      via.LogLevelInfo,
 	})
 
 	v.AppendToHead(

internal/examples/keyboard/main.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/ryanhamamura/via"
+	"github.com/ryanhamamura/via/h"
+)
+
+const gridSize = 8
+
+func main() {
+	v := via.New()
+	v.Config(via.Options{DocumentTitle: "Keyboard", ServerAddress: ":7331"})
+
+	v.Page("/", func(c *via.Context) {
+		x, y := 0, 0
+		dir := c.Signal("")
+
+		move := c.Action(func() {
+			switch dir.String() {
+			case "up":
+				y = max(0, y-1)
+			case "down":
+				y = min(gridSize-1, y+1)
+			case "left":
+				x = max(0, x-1)
+			case "right":
+				x = min(gridSize-1, x+1)
+			}
+			c.Sync()
+		})
+
+		c.View(func() h.H {
+			var rows []h.H
+			for row := range gridSize {
+				var cells []h.H
+				for col := range gridSize {
+					bg := "#e0e0e0"
+					if col == x && row == y {
+						bg = "#4a90d9"
+					}
+					cells = append(cells, h.Div(
+						h.Attr("style", fmt.Sprintf(
+							"width:48px;height:48px;background:%s;border:1px solid #ccc;",
+							bg,
+						)),
+					))
+				}
+				rows = append(rows, h.Div(
+					append([]h.H{h.Attr("style", "display:flex;")}, cells...)...,
+				))
+			}
+
+			return h.Div(
+				h.H1(h.Text("Keyboard Grid")),
+				h.P(h.Text("Move with WASD or arrow keys")),
+				h.Div(rows...),
+				via.OnKeyDownMap(
+					via.KeyBind("w", move, via.WithSignal(dir, "up")),
+					via.KeyBind("a", move, via.WithSignal(dir, "left")),
+					via.KeyBind("s", move, via.WithSignal(dir, "down")),
+					via.KeyBind("d", move, via.WithSignal(dir, "right")),
+					via.KeyBind("ArrowUp", move, via.WithSignal(dir, "up"), via.WithPreventDefault()),
+					via.KeyBind("ArrowLeft", move, via.WithSignal(dir, "left"), via.WithPreventDefault()),
+					via.KeyBind("ArrowDown", move, via.WithSignal(dir, "down"), via.WithPreventDefault()),
+					via.KeyBind("ArrowRight", move, via.WithSignal(dir, "right"), via.WithPreventDefault()),
+				),
+			)
+		})
+	})
+
+	v.Start()
+}

internal/examples/livereload/main.go

@@ -14,7 +14,7 @@ func main() {
 	v.Config(via.Options{
 		DocumentTitle: "Live Reload Demo",
 		DevMode:       true,
-		LogLvl:        via.LogLevelDebug,
+		LogLevel:      via.LogLevelDebug,
 		Plugins:       []via.Plugin{
 			// picocss.Default
 		},

internal/examples/nats-chatroom/README.md

@@ -0,0 +1,109 @@
+# NATS Chatroom Example (Embedded)
+
+A chatroom built with Via and an **embedded NATS server**, demonstrating pub/sub messaging as an alternative to the custom `Rooms` implementation in `../chatroom`.
+
+Uses `delaneyj/toolbelt/embeddednats` to run NATS inside the same binary - no external server required.
+
+## Key Differences from Original Chatroom
+
+| Aspect | Original (`../chatroom`) | This Example |
+|--------|-------------------------|--------------|
+| Pub/sub | Custom `Rooms` struct (~160 lines) | NATS subjects |
+| Member tracking | Manual `map[TU]Syncable` | NATS handles subscribers |
+| Publish timing | Ticker every 100ms + dirty flag | Instant delivery |
+| Durability | None (in-memory) | JetStream persists to disk |
+| Multi-instance | Not supported | Works across server instances |
+| External deps | None | **None** (NATS embedded in binary) |
+
+## Run the Example
+
+```bash
+go run ./internal/examples/nats-chatroom
+```
+
+That's it. No separate NATS server needed.
+
+Open multiple browser tabs at http://localhost:7331 to see messages broadcast across all clients.
+
+## How Embedded NATS Works
+
+```go
+// Start embedded NATS server (JetStream enabled by default)
+ns, err := embeddednats.New(ctx,
+    embeddednats.WithDirectory("./data/nats"),
+)
+ns.WaitForServer()
+
+// Get client connection to embedded server
+nc, err := ns.Client()
+```
+
+Data is persisted to `./data/nats/` for JetStream durability.
+
+## Architecture
+
+```
+┌─────────────────────────────────────────────────────────┐
+│                    Single Binary                         │
+│                                                          │
+│  Browser A          Embedded NATS         Browser B      │
+│      │                   │                    │          │
+│      │-- Via Action ---> │                    │          │
+│      │   (Send msg)      │                    │          │
+│      │                   │                    │          │
+│      │              nc.Publish()              │          │
+│      │              "chat.room.Go"            │          │
+│      │                   │                    │          │
+│      │<-- Subscribe -----|---- Subscribe --->│          │
+│      │    callback       │    callback        │          │
+│      │                   │                    │          │
+│      │-- c.Sync() ------>│<--- c.Sync() -----|          │
+│      │   (SSE)           │     (SSE)          │          │
+│                                                          │
+└─────────────────────────────────────────────────────────┘
+```
+
+## JetStream Durability
+
+Messages persist to disk via JetStream:
+
+```go
+js.AddStream(&nats.StreamConfig{
+    Name:      "CHAT",
+    Subjects:  []string{"chat.>"},
+    MaxMsgs:   1000,  // Keep last 1000 messages
+    MaxAge:    24 * time.Hour,
+})
+```
+
+Stop and restart the app - chat history survives.
+
+## Code Comparison
+
+**Original chatroom - 160+ lines of custom pub/sub:**
+- `Rooms` struct with named rooms
+- `Room` with member tracking, mutex, dirty flag
+- Ticker-based publish loop
+- Manual join/leave channels
+
+**This example - ~60 lines of NATS integration:**
+- `embeddednats.New()` starts the server
+- `nc.Subscribe(subject, handler)` for receiving
+- `nc.Publish(subject, data)` for sending
+- NATS handles delivery, no polling
+
+## Next Steps
+
+If this pattern proves useful, it could be promoted to a Via plugin:
+
+```go
+// Hypothetical future API
+v.Config(via.WithEmbeddedNATS("./data/nats"))
+
+// In page init
+c.Subscribe("events.user.*", func(data []byte) {
+    c.Sync()
+})
+
+c.Publish("events.user.login", userData)
+```

internal/examples/nats-chatroom/main.go

@@ -0,0 +1,284 @@
+package main
+
+import (
+	"context"
+	"log"
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/ryanhamamura/via"
+	"github.com/ryanhamamura/via/h"
+	"github.com/ryanhamamura/via/vianats"
+)
+
+var (
+	WithSignal = via.WithSignal
+)
+
+// ChatMessage represents a message in a chat room
+type ChatMessage struct {
+	User    UserInfo `json:"user"`
+	Message string   `json:"message"`
+	Time    int64    `json:"time"`
+}
+
+// UserInfo identifies a chat participant
+type UserInfo struct {
+	Name  string `json:"name"`
+	Emoji string `json:"emoji"`
+}
+
+func (u *UserInfo) Avatar() h.H {
+	return h.Div(h.Class("avatar"), h.Attr("title", u.Name), h.Text(u.Emoji))
+}
+
+var roomNames = []string{"Go", "Rust", "Python", "JavaScript", "Clojure"}
+
+func main() {
+	ctx := context.Background()
+
+	ps, err := vianats.New(ctx, "./data/nats")
+	if err != nil {
+		log.Fatalf("Failed to start embedded NATS: %v", err)
+	}
+	defer ps.Close()
+
+	err = vianats.EnsureStream(ps, vianats.StreamConfig{
+		Name:     "CHAT",
+		Subjects: []string{"chat.>"},
+		MaxMsgs:  1000,
+		MaxAge:   24 * time.Hour,
+	})
+	if err != nil {
+		log.Fatalf("Failed to ensure stream: %v", err)
+	}
+
+	v := via.New()
+	v.Config(via.Options{
+		DevMode:       true,
+		DocumentTitle: "NATS Chat",
+		LogLevel:      via.LogLevelInfo,
+		ServerAddress: ":7331",
+		PubSub:        ps,
+	})
+
+	v.AppendToHead(
+		h.Link(h.Rel("stylesheet"), h.Href("https://cdn.jsdelivr.net/npm/@picocss/pico@2/css/pico.min.css")),
+		h.StyleEl(h.Raw(`
+			body { margin: 0; }
+			main {
+				display: flex;
+				flex-direction: column;
+				height: 100vh;
+			}
+			nav[role="tab-control"] ul li a[aria-current="page"] {
+				background-color: var(--pico-primary-background);
+				color: var(--pico-primary-inverse);
+				border-bottom: 2px solid var(--pico-primary);
+			}
+			.chat-message { display: flex; gap: 0.75rem; margin-bottom: 0.5rem; }
+			.avatar {
+				width: 2rem;
+				height: 2rem;
+				border-radius: 50%;
+				background: var(--pico-muted-border-color);
+				display: grid;
+				place-items: center;
+				font-size: 1.5rem;
+				flex-shrink: 0;
+			}
+			.bubble { flex: 1; }
+			.bubble p { margin: 0; }
+			.chat-history {
+				flex: 1;
+				overflow-y: auto;
+				padding: 1rem;
+				padding-bottom: calc(88px + env(safe-area-inset-bottom));
+			}
+			.chat-input {
+				position: fixed;
+				left: 0;
+				right: 0;
+				bottom: 0;
+				background: var(--pico-background-color);
+				display: flex;
+				align-items: center;
+				gap: 0.75rem;
+				padding: 0.75rem 1rem calc(0.75rem + env(safe-area-inset-bottom));
+				border-top: 1px solid var(--pico-muted-border-color);
+			}
+			.chat-input fieldset {
+				flex: 1;
+				margin: 0;
+			}
+			.nats-badge {
+				background: #27AAE1;
+				color: white;
+				padding: 0.25rem 0.5rem;
+				border-radius: 4px;
+				font-size: 0.75rem;
+				margin-left: auto;
+			}
+		`)),
+		h.Script(h.Raw(`
+			function scrollChatToBottom() {
+				const chatHistory = document.querySelector('.chat-history');
+				if (chatHistory) chatHistory.scrollTop = chatHistory.scrollHeight;
+			}
+		`)),
+	)
+
+	v.Page("/", func(c *via.Context) {
+		currentUser := randUser()
+		roomSignal := c.Signal("Go")
+		statement := c.Signal("")
+
+		var messages []ChatMessage
+		var messagesMu sync.Mutex
+		currentRoom := "Go"
+
+		var currentSub via.Subscription
+
+		subscribeToRoom := func(room string) {
+			if currentSub != nil {
+				currentSub.Unsubscribe()
+			}
+
+			subject := "chat.room." + room
+
+			// Replay history from JetStream
+			if hist, err := vianats.ReplayHistory[ChatMessage](ps, subject, 50); err == nil {
+				messages = hist
+			}
+
+			sub, _ := via.Subscribe(c, subject, func(msg ChatMessage) {
+				messagesMu.Lock()
+				messages = append(messages, msg)
+				if len(messages) > 50 {
+					messages = messages[len(messages)-50:]
+				}
+				messagesMu.Unlock()
+				c.Sync()
+			})
+			currentSub = sub
+			currentRoom = room
+		}
+
+		subscribeToRoom("Go")
+
+		switchRoom := c.Action(func() {
+			newRoom := roomSignal.String()
+			if newRoom != currentRoom {
+				messagesMu.Lock()
+				messages = nil
+				messagesMu.Unlock()
+				subscribeToRoom(newRoom)
+				c.Sync()
+			}
+		})
+
+		say := c.Action(func() {
+			msg := statement.String()
+			if msg == "" {
+				msg = randomDevQuote()
+			}
+			statement.SetValue("")
+
+			via.Publish(c, "chat.room."+currentRoom, ChatMessage{
+				User:    currentUser,
+				Message: msg,
+				Time:    time.Now().UnixMilli(),
+			})
+		})
+
+		c.View(func() h.H {
+			var tabs []h.H
+			for _, name := range roomNames {
+				isCurrent := name == currentRoom
+				tabs = append(tabs, h.Li(
+					h.A(
+						h.If(isCurrent, h.Attr("aria-current", "page")),
+						h.Text(name),
+						switchRoom.OnClick(WithSignal(roomSignal, name)),
+					),
+				))
+			}
+
+			messagesMu.Lock()
+			chatHistoryChildren := []h.H{
+				h.Class("chat-history"),
+				h.Script(h.Raw(`new MutationObserver(()=>scrollChatToBottom()).observe(document.querySelector('.chat-history'), {childList:true})`)),
+			}
+			for _, msg := range messages {
+				chatHistoryChildren = append(chatHistoryChildren,
+					h.Div(h.Class("chat-message"),
+						h.Div(h.Class("avatar"), h.Attr("title", msg.User.Name), h.Text(msg.User.Emoji)),
+						h.Div(h.Class("bubble"),
+							h.P(h.Text(msg.Message)),
+						),
+					),
+				)
+			}
+			messagesMu.Unlock()
+
+			return h.Main(h.Class("container"),
+				h.Nav(
+					h.Attr("role", "tab-control"),
+					h.Ul(tabs...),
+					h.Span(h.Class("nats-badge"), h.Text("NATS")),
+				),
+				h.Div(chatHistoryChildren...),
+				h.Div(
+					h.Class("chat-input"),
+					currentUser.Avatar(),
+					h.FieldSet(
+						h.Attr("role", "group"),
+						h.Input(
+							h.Type("text"),
+							h.Placeholder(currentUser.Name+" says..."),
+							statement.Bind(),
+							h.Attr("autofocus"),
+							say.OnKeyDown("Enter"),
+						),
+						h.Button(h.Text("Send"), say.OnClick()),
+					),
+				),
+			)
+		})
+	})
+
+	log.Println("Starting NATS chatroom on :7331 (embedded NATS server)")
+	v.Start()
+}
+
+func randUser() UserInfo {
+	adjectives := []string{"Happy", "Clever", "Brave", "Swift", "Gentle", "Wise", "Bold", "Calm", "Eager", "Fierce"}
+	animals := []string{"Panda", "Tiger", "Eagle", "Dolphin", "Fox", "Wolf", "Bear", "Hawk", "Otter", "Lion"}
+	emojis := []string{"🐼", "🐯", "🦅", "🐬", "🦊", "🐺", "🐻", "🦅", "🦦", "🦁"}
+
+	idx := rand.Intn(len(animals))
+	return UserInfo{
+		Name:  adjectives[rand.Intn(len(adjectives))] + " " + animals[idx],
+		Emoji: emojis[idx],
+	}
+}
+
+var quoteIdx = rand.Intn(len(devQuotes))
+var devQuotes = []string{
+	"Just use NATS.",
+	"Pub/sub all the things!",
+	"Messages are the new API.",
+	"JetStream for durability.",
+	"No more polling.",
+	"Event-driven architecture FTW.",
+	"Decouple everything.",
+	"NATS is fast.",
+	"Subjects are like topics.",
+	"Request-reply is cool.",
+}
+
+func randomDevQuote() string {
+	quoteIdx = (quoteIdx + 1) % len(devQuotes)
+	return devQuotes[quoteIdx]
+}

internal/examples/pubsub-crud/main.go

@@ -0,0 +1,284 @@
+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"fmt"
+	"html"
+	"log"
+	"sync"
+	"time"
+
+	"github.com/ryanhamamura/via"
+	"github.com/ryanhamamura/via/h"
+	"github.com/ryanhamamura/via/vianats"
+)
+
+var WithSignal = via.WithSignal
+
+type Bookmark struct {
+	ID    string
+	Title string
+	URL   string
+}
+
+type CRUDEvent struct {
+	Action string `json:"action"`
+	Title  string `json:"title"`
+	UserID string `json:"user_id"`
+}
+
+var (
+	bookmarks   []Bookmark
+	bookmarksMu sync.RWMutex
+)
+
+func randomHex(n int) string {
+	b := make([]byte, n)
+	rand.Read(b)
+	return fmt.Sprintf("%x", b)
+}
+
+func findBookmark(id string) (Bookmark, int) {
+	for i, bm := range bookmarks {
+		if bm.ID == id {
+			return bm, i
+		}
+	}
+	return Bookmark{}, -1
+}
+
+func main() {
+	ctx := context.Background()
+
+	ps, err := vianats.New(ctx, "./data/nats")
+	if err != nil {
+		log.Fatalf("Failed to start embedded NATS: %v", err)
+	}
+	defer ps.Close()
+
+	err = vianats.EnsureStream(ps, vianats.StreamConfig{
+		Name:     "BOOKMARKS",
+		Subjects: []string{"bookmarks.>"},
+		MaxMsgs:  1000,
+		MaxAge:   24 * time.Hour,
+	})
+	if err != nil {
+		log.Fatalf("Failed to ensure stream: %v", err)
+	}
+
+	v := via.New()
+	v.Config(via.Options{
+		DevMode:       true,
+		DocumentTitle: "Bookmarks",
+		LogLevel:      via.LogLevelInfo,
+		ServerAddress: ":7331",
+		PubSub:        ps,
+	})
+
+	v.AppendToHead(
+		h.Link(h.Rel("stylesheet"), h.Href("https://cdn.jsdelivr.net/npm/daisyui@4/dist/full.min.css")),
+		h.Script(h.Src("https://cdn.tailwindcss.com")),
+	)
+
+	v.Page("/", func(c *via.Context) {
+		userID := randomHex(8)
+
+		titleSignal := c.Signal("")
+		urlSignal := c.Signal("")
+		targetIDSignal := c.Signal("")
+
+		via.Subscribe(c, "bookmarks.events", func(evt CRUDEvent) {
+			if evt.UserID == userID {
+				return
+			}
+			safeTitle := html.EscapeString(evt.Title)
+			var alertClass string
+			switch evt.Action {
+			case "created":
+				alertClass = "alert-success"
+			case "updated":
+				alertClass = "alert-info"
+			case "deleted":
+				alertClass = "alert-error"
+			}
+			c.ExecScript(fmt.Sprintf(`(function(){
+				var tc = document.getElementById('toast-container');
+				if (!tc) return;
+				var d = document.createElement('div');
+				d.className = 'alert %s';
+				d.innerHTML = '<span>Bookmark "%s" %s</span>';
+				tc.appendChild(d);
+				setTimeout(function(){ d.remove(); }, 3000);
+			})()`, alertClass, safeTitle, evt.Action))
+			c.Sync()
+		})
+
+		save := c.Action(func() {
+			title := titleSignal.String()
+			url := urlSignal.String()
+			if title == "" || url == "" {
+				return
+			}
+
+			targetID := targetIDSignal.String()
+			action := "created"
+
+			bookmarksMu.Lock()
+			if targetID != "" {
+				if _, idx := findBookmark(targetID); idx >= 0 {
+					bookmarks[idx].Title = title
+					bookmarks[idx].URL = url
+					action = "updated"
+				}
+			} else {
+				bookmarks = append(bookmarks, Bookmark{
+					ID:    randomHex(8),
+					Title: title,
+					URL:   url,
+				})
+			}
+			bookmarksMu.Unlock()
+
+			titleSignal.SetValue("")
+			urlSignal.SetValue("")
+			targetIDSignal.SetValue("")
+
+			via.Publish(c, "bookmarks.events", CRUDEvent{
+				Action: action,
+				Title:  title,
+				UserID: userID,
+			})
+			c.Sync()
+		})
+
+		edit := c.Action(func() {
+			id := targetIDSignal.String()
+			bookmarksMu.RLock()
+			bm, idx := findBookmark(id)
+			bookmarksMu.RUnlock()
+			if idx < 0 {
+				return
+			}
+			titleSignal.SetValue(bm.Title)
+			urlSignal.SetValue(bm.URL)
+		})
+
+		del := c.Action(func() {
+			id := targetIDSignal.String()
+			bookmarksMu.Lock()
+			bm, idx := findBookmark(id)
+			if idx >= 0 {
+				bookmarks = append(bookmarks[:idx], bookmarks[idx+1:]...)
+			}
+			bookmarksMu.Unlock()
+			if idx < 0 {
+				return
+			}
+
+			targetIDSignal.SetValue("")
+
+			via.Publish(c, "bookmarks.events", CRUDEvent{
+				Action: "deleted",
+				Title:  bm.Title,
+				UserID: userID,
+			})
+			c.Sync()
+		})
+
+		cancelEdit := c.Action(func() {
+			titleSignal.SetValue("")
+			urlSignal.SetValue("")
+			targetIDSignal.SetValue("")
+		})
+
+		c.View(func() h.H {
+			isEditing := targetIDSignal.String() != ""
+
+			// Build table rows
+			bookmarksMu.RLock()
+			var rows []h.H
+			for _, bm := range bookmarks {
+				rows = append(rows, h.Tr(
+					h.Td(h.Text(bm.Title)),
+					h.Td(h.A(h.Href(bm.URL), h.Attr("target", "_blank"), h.Class("link link-primary"), h.Text(bm.URL))),
+					h.Td(
+						h.Div(h.Class("flex gap-1"),
+							h.Button(h.Class("btn btn-xs btn-ghost"), h.Text("Edit"),
+								edit.OnClick(WithSignal(targetIDSignal, bm.ID)),
+							),
+							h.Button(h.Class("btn btn-xs btn-ghost text-error"), h.Text("Delete"),
+								del.OnClick(WithSignal(targetIDSignal, bm.ID)),
+							),
+						),
+					),
+				))
+			}
+			bookmarksMu.RUnlock()
+
+			saveLabel := "Add Bookmark"
+			if isEditing {
+				saveLabel = "Update Bookmark"
+			}
+
+			return h.Div(h.Class("min-h-screen bg-base-200"),
+				// Navbar
+				h.Div(h.Class("navbar bg-base-100 shadow-sm"),
+					h.Div(h.Class("flex-1"),
+						h.A(h.Class("btn btn-ghost text-xl"), h.Text("Bookmarks")),
+					),
+					h.Div(h.Class("flex-none"),
+						h.Div(h.Class("badge badge-outline"), h.Text(userID[:8])),
+					),
+				),
+
+				h.Div(h.Class("container mx-auto p-4 max-w-3xl flex flex-col gap-4"),
+					// Form card
+					h.Div(h.Class("card bg-base-100 shadow"),
+						h.Div(h.Class("card-body"),
+							h.H2(h.Class("card-title"), h.Text(saveLabel)),
+							h.Div(h.Class("flex flex-col gap-2"),
+								h.Input(h.Class("input input-bordered w-full"), h.Type("text"), h.Placeholder("Title"), titleSignal.Bind()),
+								h.Input(h.Class("input input-bordered w-full"), h.Type("text"), h.Placeholder("https://example.com"), urlSignal.Bind()),
+								h.Div(h.Class("card-actions justify-end"),
+									h.If(isEditing,
+										h.Button(h.Class("btn btn-ghost"), h.Text("Cancel"), cancelEdit.OnClick()),
+									),
+									h.Button(h.Class("btn btn-primary"), h.Text(saveLabel), save.OnClick()),
+								),
+							),
+						),
+					),
+
+					// Table card
+					h.Div(h.Class("card bg-base-100 shadow"),
+						h.Div(h.Class("card-body"),
+							h.H2(h.Class("card-title"), h.Text("All Bookmarks")),
+							h.If(len(rows) == 0,
+								h.P(h.Class("text-base-content/60"), h.Text("No bookmarks yet. Add one above!")),
+							),
+							h.If(len(rows) > 0,
+								h.Div(h.Class("overflow-x-auto"),
+									h.Table(h.Class("table"),
+										h.THead(h.Tr(
+											h.Th(h.Text("Title")),
+											h.Th(h.Text("URL")),
+											h.Th(h.Text("Actions")),
+										)),
+										h.TBody(rows...),
+									),
+								),
+							),
+						),
+					),
+				),
+
+				// Toast container — ignored by morph so Sync() doesn't wipe active toasts
+				h.Div(h.ID("toast-container"), h.Class("toast toast-end toast-top"), h.DataIgnoreMorph()),
+			)
+		})
+	})
+
+	log.Println("Starting pubsub-crud example on :7331")
+	v.Start()
+}

internal/examples/realtimechart/main.go

@@ -14,7 +14,7 @@ func main() {
 	v := via.New()
 
 	v.Config(via.Options{
-		LogLvl:  via.LogLevelDebug,
+		LogLevel: via.LogLevelDebug,
 		DevMode: true,
 		Plugins: []via.Plugin{
 			// picocss.Default,

internal/examples/shakespeare/main.go

@@ -54,7 +54,7 @@ func main() {
 	v.Config(via.Options{
 		DevMode:       true,
 		DocumentTitle: "Search",
-		LogLvl:        via.LogLevelWarn,
+		LogLevel:      via.LogLevelWarn,
 	})
 
 	v.AppendToHead(

nats_test.go

@@ -0,0 +1,195 @@
+package via
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/ryanhamamura/via/h"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type mockHandler struct {
+	id     int64
+	fn     func([]byte)
+	active atomic.Bool
+}
+
+// mockPubSub implements PubSub for testing without NATS.
+type mockPubSub struct {
+	mu    sync.Mutex
+	subs  map[string][]*mockHandler
+	nextID atomic.Int64
+}
+
+func newMockPubSub() *mockPubSub {
+	return &mockPubSub{subs: make(map[string][]*mockHandler)}
+}
+
+func (m *mockPubSub) Publish(subject string, data []byte) error {
+	m.mu.Lock()
+	handlers := make([]*mockHandler, len(m.subs[subject]))
+	copy(handlers, m.subs[subject])
+	m.mu.Unlock()
+	for _, h := range handlers {
+		if h.active.Load() {
+			h.fn(data)
+		}
+	}
+	return nil
+}
+
+func (m *mockPubSub) Subscribe(subject string, handler func(data []byte)) (Subscription, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	mh := &mockHandler{
+		id: m.nextID.Add(1),
+		fn: handler,
+	}
+	mh.active.Store(true)
+	m.subs[subject] = append(m.subs[subject], mh)
+	return &mockSub{handler: mh}, nil
+}
+
+func (m *mockPubSub) Close() error { return nil }
+
+type mockSub struct {
+	handler *mockHandler
+}
+
+func (s *mockSub) Unsubscribe() error {
+	s.handler.active.Store(false)
+	return nil
+}
+
+func TestPubSub_RoundTrip(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	var received []byte
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	c := newContext("test-ctx", "/", v)
+	c.View(func() h.H { return h.Div() })
+
+	_, err := c.Subscribe("test.topic", func(data []byte) {
+		received = data
+		wg.Done()
+	})
+	require.NoError(t, err)
+
+	err = c.Publish("test.topic", []byte("hello"))
+	require.NoError(t, err)
+
+	wg.Wait()
+	assert.Equal(t, []byte("hello"), received)
+}
+
+func TestPubSub_MultipleSubscribers(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	var mu sync.Mutex
+	var results []string
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	c1 := newContext("ctx-1", "/", v)
+	c1.View(func() h.H { return h.Div() })
+	c2 := newContext("ctx-2", "/", v)
+	c2.View(func() h.H { return h.Div() })
+
+	c1.Subscribe("broadcast", func(data []byte) {
+		mu.Lock()
+		results = append(results, "c1:"+string(data))
+		mu.Unlock()
+		wg.Done()
+	})
+
+	c2.Subscribe("broadcast", func(data []byte) {
+		mu.Lock()
+		results = append(results, "c2:"+string(data))
+		mu.Unlock()
+		wg.Done()
+	})
+
+	c1.Publish("broadcast", []byte("msg"))
+	wg.Wait()
+
+	assert.Len(t, results, 2)
+	assert.Contains(t, results, "c1:msg")
+	assert.Contains(t, results, "c2:msg")
+}
+
+func TestPubSub_SubscriptionCleanupOnDispose(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	c := newContext("cleanup-ctx", "/", v)
+	c.View(func() h.H { return h.Div() })
+
+	c.Subscribe("room.1", func(data []byte) {})
+	c.Subscribe("room.2", func(data []byte) {})
+
+	assert.Len(t, c.subscriptions, 2)
+
+	c.unsubscribeAll()
+	assert.Empty(t, c.subscriptions)
+}
+
+func TestPubSub_ManualUnsubscribe(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	c := newContext("unsub-ctx", "/", v)
+	c.View(func() h.H { return h.Div() })
+
+	called := false
+	sub, err := c.Subscribe("topic", func(data []byte) {
+		called = true
+	})
+	require.NoError(t, err)
+
+	sub.Unsubscribe()
+
+	c.Publish("topic", []byte("ignored"))
+	time.Sleep(10 * time.Millisecond)
+	assert.False(t, called)
+}
+
+func TestPubSub_NoOpWhenNotConfigured(t *testing.T) {
+	v := New()
+
+	c := newContext("noop-ctx", "/", v)
+	c.View(func() h.H { return h.Div() })
+
+	err := c.Publish("topic", []byte("data"))
+	assert.Error(t, err)
+
+	sub, err := c.Subscribe("topic", func(data []byte) {})
+	assert.Error(t, err)
+	assert.Nil(t, sub)
+}
+
+func TestPubSub_NoOpDuringPanicCheck(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	// Panic-check context has id=""
+	c := newContext("", "/", v)
+
+	err := c.Publish("topic", []byte("data"))
+	assert.NoError(t, err)
+
+	sub, err := c.Subscribe("topic", func(data []byte) {})
+	assert.NoError(t, err)
+	assert.Nil(t, sub)
+}

pubsub.go

@@ -0,0 +1,14 @@
+package via
+
+// PubSub is an interface for publish/subscribe messaging backends.
+// The vianats sub-package provides an embedded NATS implementation.
+type PubSub interface {
+	Publish(subject string, data []byte) error
+	Subscribe(subject string, handler func(data []byte)) (Subscription, error)
+	Close() error
+}
+
+// Subscription represents an active subscription that can be manually unsubscribed.
+type Subscription interface {
+	Unsubscribe() error
+}

pubsub_helpers.go

@@ -0,0 +1,23 @@
+package via
+
+import "encoding/json"
+
+// Publish JSON-marshals msg and publishes to subject.
+func Publish[T any](c *Context, subject string, msg T) error {
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return err
+	}
+	return c.Publish(subject, data)
+}
+
+// Subscribe JSON-unmarshals each message as T and calls handler.
+func Subscribe[T any](c *Context, subject string, handler func(T)) (Subscription, error) {
+	return c.Subscribe(subject, func(data []byte) {
+		var msg T
+		if err := json.Unmarshal(data, &msg); err != nil {
+			return
+		}
+		handler(msg)
+	})
+}

pubsub_helpers_test.go

@@ -0,0 +1,66 @@
+package via
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/ryanhamamura/via/h"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPublishSubscribe_RoundTrip(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	type event struct {
+		Name  string `json:"name"`
+		Count int    `json:"count"`
+	}
+
+	var got event
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	c := newContext("typed-ctx", "/", v)
+	c.View(func() h.H { return h.Div() })
+
+	_, err := Subscribe(c, "events", func(e event) {
+		got = e
+		wg.Done()
+	})
+	require.NoError(t, err)
+
+	err = Publish(c, "events", event{Name: "click", Count: 42})
+	require.NoError(t, err)
+
+	wg.Wait()
+	assert.Equal(t, "click", got.Name)
+	assert.Equal(t, 42, got.Count)
+}
+
+func TestSubscribe_SkipsBadJSON(t *testing.T) {
+	ps := newMockPubSub()
+	v := New()
+	v.Config(Options{PubSub: ps})
+
+	type msg struct {
+		Text string `json:"text"`
+	}
+
+	called := false
+	c := newContext("bad-json-ctx", "/", v)
+	c.View(func() h.H { return h.Div() })
+
+	_, err := Subscribe(c, "topic", func(m msg) {
+		called = true
+	})
+	require.NoError(t, err)
+
+	// Publish raw invalid JSON — handler should silently skip
+	err = c.Publish("topic", []byte("not json"))
+	require.NoError(t, err)
+
+	assert.False(t, called)
+}

via.go

@@ -7,21 +7,25 @@
 package via
 
 import (
+	"context"
 	"crypto/rand"
 	_ "embed"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"io"
-	"log"
 	"net/http"
 	"net/url"
 	"os"
+	ossignal "os/signal"
 	"path/filepath"
 	"strings"
 	"sync"
+	"syscall"
+	"time"
 
 	"github.com/alexedwards/scs/v2"
+	"github.com/rs/zerolog"
 	"github.com/ryanhamamura/via/h"
 	"github.com/starfederation/datastar-go/datastar"
 )
@@ -34,63 +38,66 @@ var datastarJS []byte
 type V struct {
 	cfg                       Options
 	mux                       *http.ServeMux
+	server                    *http.Server
+	logger                    zerolog.Logger
 	contextRegistry           map[string]*Context
 	contextRegistryMutex      sync.RWMutex
 	documentHeadIncludes      []h.H
 	documentFootIncludes      []h.H
 	devModePageInitFnMap      map[string]func(*Context)
 	sessionManager  *scs.SessionManager
+	pubsub          PubSub
 	datastarPath    string
 	datastarContent []byte
 	datastarOnce    sync.Once
 }
 
+func (v *V) logEvent(evt *zerolog.Event, c *Context) *zerolog.Event {
+	if c != nil && c.id != "" {
+		evt = evt.Str("via-ctx", c.id)
+	}
+	return evt
+}
+
 func (v *V) logFatal(format string, a ...any) {
-	log.Printf("[fatal] msg=%q", fmt.Sprintf(format, a...))
+	v.logEvent(v.logger.WithLevel(zerolog.FatalLevel), nil).Msgf(format, a...)
 }
 
 func (v *V) logErr(c *Context, format string, a ...any) {
-	cRef := ""
+	v.logEvent(v.logger.Error(), c).Msgf(format, a...)
-	if c != nil && c.id != "" {
-		cRef = fmt.Sprintf("via-ctx=%q ", c.id)
-	}
-	log.Printf("[error] %smsg=%q", cRef, fmt.Sprintf(format, a...))
 }
 
 func (v *V) logWarn(c *Context, format string, a ...any) {
-	cRef := ""
+	v.logEvent(v.logger.Warn(), c).Msgf(format, a...)
-	if c != nil && c.id != "" {
-		cRef = fmt.Sprintf("via-ctx=%q ", c.id)
-	}
-	if v.cfg.LogLvl >= LogLevelWarn {
-		log.Printf("[warn] %smsg=%q", cRef, fmt.Sprintf(format, a...))
-	}
 }
 
 func (v *V) logInfo(c *Context, format string, a ...any) {
-	cRef := ""
+	v.logEvent(v.logger.Info(), c).Msgf(format, a...)
-	if c != nil && c.id != "" {
-		cRef = fmt.Sprintf("via-ctx=%q ", c.id)
-	}
-	if v.cfg.LogLvl >= LogLevelInfo {
-		log.Printf("[info] %smsg=%q", cRef, fmt.Sprintf(format, a...))
-	}
 }
 
 func (v *V) logDebug(c *Context, format string, a ...any) {
-	cRef := ""
+	v.logEvent(v.logger.Debug(), c).Msgf(format, a...)
-	if c != nil && c.id != "" {
+}
-		cRef = fmt.Sprintf("via-ctx=%q ", c.id)
+
-	}
+func newConsoleLogger(level zerolog.Level) zerolog.Logger {
-	if v.cfg.LogLvl == LogLevelDebug {
+	return zerolog.New(zerolog.ConsoleWriter{Out: os.Stderr, TimeFormat: "15:04:05"}).
-		log.Printf("[debug] %smsg=%q", cRef, fmt.Sprintf(format, a...))
+		With().Timestamp().Logger().Level(level)
-	}
 }
 
 // Config overrides the default configuration with the given options.
 func (v *V) Config(cfg Options) {
-	if cfg.LogLvl != undefined {
+	if cfg.Logger != nil {
-		v.cfg.LogLvl = cfg.LogLvl
+		v.logger = *cfg.Logger
+	} else if cfg.LogLevel != nil || cfg.DevMode != v.cfg.DevMode {
+		level := zerolog.InfoLevel
+		if cfg.LogLevel != nil {
+			level = *cfg.LogLevel
+		}
+		if cfg.DevMode {
+			v.logger = newConsoleLogger(level)
+		} else {
+			v.logger = zerolog.New(os.Stderr).With().Timestamp().Logger().Level(level)
+		}
 	}
 	if cfg.DocumentTitle != "" {
 		v.cfg.DocumentTitle = cfg.DocumentTitle
@@ -117,6 +124,9 @@ func (v *V) Config(cfg Options) {
 	if cfg.DatastarPath != "" {
 		v.datastarPath = cfg.DatastarPath
 	}
+	if cfg.PubSub != nil {
+		v.pubsub = cfg.PubSub
+	}
 }
 
 // AppendToHead appends the given h.H nodes to the head of the base HTML document.
@@ -249,14 +259,82 @@ func (v *V) getCtx(id string) (*Context, error) {
 	return nil, fmt.Errorf("ctx '%s' not found", id)
 }
 
-// Start starts the Via HTTP server on the given address.
+// Start starts the Via HTTP server and blocks until a SIGINT or SIGTERM
+// signal is received, then performs a graceful shutdown.
 func (v *V) Start() {
-	v.logInfo(nil, "via started at [%s]", v.cfg.ServerAddress)
 	handler := http.Handler(v.mux)
 	if v.sessionManager != nil {
 		handler = v.sessionManager.LoadAndSave(v.mux)
 	}
-	log.Fatalf("[fatal] %v", http.ListenAndServe(v.cfg.ServerAddress, handler))
+	v.server = &http.Server{
+		Addr:    v.cfg.ServerAddress,
+		Handler: handler,
+	}
+
+	errCh := make(chan error, 1)
+	go func() {
+		errCh <- v.server.ListenAndServe()
+	}()
+
+	v.logInfo(nil, "via started at [%s]", v.cfg.ServerAddress)
+
+	sigCh := make(chan os.Signal, 1)
+	ossignal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+
+	select {
+	case sig := <-sigCh:
+		v.logInfo(nil, "received signal %v, shutting down", sig)
+	case err := <-errCh:
+		if err != nil && err != http.ErrServerClosed {
+			v.logger.Fatal().Err(err).Msg("http server failed")
+		}
+		return
+	}
+
+	v.shutdown()
+}
+
+// Shutdown gracefully shuts down the server and all contexts.
+// Safe for programmatic or test use.
+func (v *V) Shutdown() {
+	v.shutdown()
+}
+
+func (v *V) shutdown() {
+	v.logInfo(nil, "draining all contexts")
+	v.drainAllContexts()
+
+	if v.server != nil {
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if err := v.server.Shutdown(ctx); err != nil {
+			v.logErr(nil, "http server shutdown error: %v", err)
+		}
+	}
+
+	if v.pubsub != nil {
+		if err := v.pubsub.Close(); err != nil {
+			v.logErr(nil, "pubsub close error: %v", err)
+		}
+	}
+
+	v.logInfo(nil, "shutdown complete")
+}
+
+func (v *V) drainAllContexts() {
+	v.contextRegistryMutex.Lock()
+	contexts := make([]*Context, 0, len(v.contextRegistry))
+	for _, c := range v.contextRegistry {
+		contexts = append(contexts, c)
+	}
+	v.contextRegistry = make(map[string]*Context)
+	v.contextRegistryMutex.Unlock()
+
+	for _, c := range contexts {
+		v.logDebug(c, "disposing context")
+		c.dispose()
+	}
+	v.logInfo(nil, "drained %d context(s)", len(contexts))
 }
 
 // HTTPServeMux returns the underlying HTTP request multiplexer to enable user extentions, middleware and
@@ -280,7 +358,7 @@ func (v *V) ensureDatastarHandler() {
 func (v *V) devModePersist(c *Context) {
 	p := filepath.Join(".via", "devmode", "ctx.json")
 	if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {
-		log.Fatalf("failed to create directory for devmode files: %v", err)
+		v.logFatal("failed to create directory for devmode files: %v", err)
 	}
 
 	// load persisted list from file, or empty list if file not found
@@ -394,6 +472,7 @@ func New() *V {
 
 	v := &V{
 		mux:                  mux,
+		logger:               newConsoleLogger(zerolog.InfoLevel),
 		contextRegistry:      make(map[string]*Context),
 		devModePageInitFnMap: make(map[string]func(*Context)),
 		sessionManager:       scs.New(),
@@ -402,7 +481,6 @@ func New() *V {
 		cfg: Options{
 			DevMode:       false,
 			ServerAddress: ":3000",
-			LogLvl:        LogLevelInfo,
 			DocumentTitle: "⚡ Via",
 		},
 	}
@@ -440,10 +518,10 @@ func New() *V {
 			case <-sse.Context().Done():
 				v.logDebug(c, "SSE connection ended")
 				return
-			case patch, ok := <-c.patchChan:
+			case <-c.ctxDisposedChan:
-				if !ok {
+				v.logDebug(c, "context disposed, closing SSE")
-					continue
+				return
-				}
+			case patch := <-c.patchChan:
 				switch patch.typ {
 				case patchTypeElements:
 					if err := sse.PatchElements(patch.content); err != nil {
@@ -514,7 +592,7 @@ func New() *V {
 	v.mux.HandleFunc("POST /_session/close", func(w http.ResponseWriter, r *http.Request) {
 		body, err := io.ReadAll(r.Body)
 		if err != nil {
-			log.Printf("Error reading body: %v", err)
+			v.logErr(nil, "error reading body: %v", err)
 			w.WriteHeader(http.StatusBadRequest)
 			return
 		}
@@ -525,7 +603,7 @@ func New() *V {
 			v.logErr(c, "failed to handle session close: %v", err)
 			return
 		}
-		c.stopAllRoutines()
+		c.dispose()
 		v.logDebug(c, "session close event triggered")
 		if v.cfg.DevMode {
 			v.devModeRemovePersisted(c)

via_test.go

@@ -128,6 +128,101 @@ func TestAction(t *testing.T) {
 	assert.Contains(t, body, "/_action/")
 }
 
+func TestOnKeyDownWithWindow(t *testing.T) {
+	var trigger *actionTrigger
+	v := New()
+	v.Page("/", func(c *Context) {
+		trigger = c.Action(func() {})
+		c.View(func() h.H {
+			return h.Div(trigger.OnKeyDown("Enter", WithWindow()))
+		})
+	})
+
+	req := httptest.NewRequest("GET", "/", nil)
+	w := httptest.NewRecorder()
+	v.mux.ServeHTTP(w, req)
+	body := w.Body.String()
+	assert.Contains(t, body, "data-on:keydown__window")
+	assert.Contains(t, body, "evt.key==='Enter'")
+}
+
+func TestOnKeyDownMap(t *testing.T) {
+	t.Run("multiple bindings with different actions", func(t *testing.T) {
+		var move, shoot *actionTrigger
+		var dir *signal
+		v := New()
+		v.Page("/", func(c *Context) {
+			dir = c.Signal("none")
+			move = c.Action(func() {})
+			shoot = c.Action(func() {})
+			c.View(func() h.H {
+				return h.Div(
+					OnKeyDownMap(
+						KeyBind("w", move, WithSignal(dir, "up")),
+						KeyBind("ArrowUp", move, WithSignal(dir, "up"), WithPreventDefault()),
+						KeyBind(" ", shoot, WithPreventDefault()),
+					),
+				)
+			})
+		})
+
+		req := httptest.NewRequest("GET", "/", nil)
+		w := httptest.NewRecorder()
+		v.mux.ServeHTTP(w, req)
+		body := w.Body.String()
+
+		// Single attribute, window-scoped
+		assert.Contains(t, body, "data-on:keydown__window")
+
+		// Key dispatching
+		assert.Contains(t, body, "evt.key==='w'")
+		assert.Contains(t, body, "evt.key==='ArrowUp'")
+		assert.Contains(t, body, "evt.key===' '")
+
+		// Different actions referenced
+		assert.Contains(t, body, "/_action/"+move.id)
+		assert.Contains(t, body, "/_action/"+shoot.id)
+
+		// preventDefault only on ArrowUp and space branches
+		assert.Contains(t, body, "evt.key==='ArrowUp' ? (evt.preventDefault()")
+		assert.Contains(t, body, "evt.key===' ' ? (evt.preventDefault()")
+
+		// 'w' branch should NOT have preventDefault
+		assert.NotContains(t, body, "evt.key==='w' ? (evt.preventDefault()")
+	})
+
+	t.Run("WithSignal per binding", func(t *testing.T) {
+		var move *actionTrigger
+		var dir *signal
+		v := New()
+		v.Page("/", func(c *Context) {
+			dir = c.Signal("none")
+			move = c.Action(func() {})
+			c.View(func() h.H {
+				return h.Div(
+					OnKeyDownMap(
+						KeyBind("w", move, WithSignal(dir, "up")),
+						KeyBind("s", move, WithSignal(dir, "down")),
+					),
+				)
+			})
+		})
+
+		req := httptest.NewRequest("GET", "/", nil)
+		w := httptest.NewRecorder()
+		v.mux.ServeHTTP(w, req)
+		body := w.Body.String()
+
+		assert.Contains(t, body, "$"+dir.ID()+"='up'")
+		assert.Contains(t, body, "$"+dir.ID()+"='down'")
+	})
+
+	t.Run("empty bindings returns nil", func(t *testing.T) {
+		result := OnKeyDownMap()
+		assert.Nil(t, result)
+	})
+}
+
 func TestConfig(t *testing.T) {
 	v := New()
 	v.Config(Options{DocumentTitle: "Test"})

vianats/vianats.go

@@ -0,0 +1,127 @@
+// Package vianats provides an embedded NATS server with JetStream as a
+// pub/sub backend for Via applications.
+package vianats
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/delaneyj/toolbelt/embeddednats"
+	"github.com/nats-io/nats.go"
+	"github.com/ryanhamamura/via"
+)
+
+// NATS implements via.PubSub using an embedded NATS server with JetStream.
+type NATS struct {
+	server *embeddednats.Server
+	nc     *nats.Conn
+	js     nats.JetStreamContext
+}
+
+// New starts an embedded NATS server with JetStream enabled and returns a
+// ready-to-use NATS instance. The server stores data in dataDir and shuts
+// down when ctx is cancelled.
+func New(ctx context.Context, dataDir string) (*NATS, error) {
+	ns, err := embeddednats.New(ctx, embeddednats.WithDirectory(dataDir))
+	if err != nil {
+		return nil, fmt.Errorf("vianats: start server: %w", err)
+	}
+	ns.WaitForServer()
+
+	nc, err := ns.Client()
+	if err != nil {
+		ns.Close()
+		return nil, fmt.Errorf("vianats: connect client: %w", err)
+	}
+
+	js, err := nc.JetStream()
+	if err != nil {
+		nc.Close()
+		ns.Close()
+		return nil, fmt.Errorf("vianats: init jetstream: %w", err)
+	}
+
+	return &NATS{server: ns, nc: nc, js: js}, nil
+}
+
+// Publish sends data to the given subject using core NATS publish.
+// JetStream captures messages automatically if a matching stream exists.
+func (n *NATS) Publish(subject string, data []byte) error {
+	return n.nc.Publish(subject, data)
+}
+
+// Subscribe creates a core NATS subscription for real-time fan-out delivery.
+func (n *NATS) Subscribe(subject string, handler func(data []byte)) (via.Subscription, error) {
+	sub, err := n.nc.Subscribe(subject, func(msg *nats.Msg) {
+		handler(msg.Data)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return sub, nil
+}
+
+// Close shuts down the client connection and embedded server.
+func (n *NATS) Close() error {
+	n.nc.Close()
+	return n.server.Close()
+}
+
+// Conn returns the underlying NATS connection for advanced usage.
+func (n *NATS) Conn() *nats.Conn {
+	return n.nc
+}
+
+// JetStream returns the JetStream context for stream configuration and replay.
+func (n *NATS) JetStream() nats.JetStreamContext {
+	return n.js
+}
+
+// StreamConfig holds the parameters for creating or updating a JetStream stream.
+type StreamConfig struct {
+	Name     string
+	Subjects []string
+	MaxMsgs  int64
+	MaxAge   time.Duration
+}
+
+// EnsureStream creates or updates a JetStream stream matching cfg.
+func EnsureStream(n *NATS, cfg StreamConfig) error {
+	_, err := n.js.AddStream(&nats.StreamConfig{
+		Name:      cfg.Name,
+		Subjects:  cfg.Subjects,
+		Retention: nats.LimitsPolicy,
+		MaxMsgs:   cfg.MaxMsgs,
+		MaxAge:    cfg.MaxAge,
+	})
+	return err
+}
+
+// ReplayHistory fetches the last limit messages from subject,
+// deserializing each as T. Returns an empty slice if nothing is available.
+func ReplayHistory[T any](n *NATS, subject string, limit int) ([]T, error) {
+	sub, err := n.js.SubscribeSync(subject, nats.DeliverAll(), nats.OrderedConsumer())
+	if err != nil {
+		return nil, err
+	}
+	defer sub.Unsubscribe()
+
+	var msgs []T
+	for {
+		raw, err := sub.NextMsg(200 * time.Millisecond)
+		if err != nil {
+			break
+		}
+		var msg T
+		if json.Unmarshal(raw.Data, &msg) == nil {
+			msgs = append(msgs, msg)
+		}
+	}
+
+	if limit > 0 && len(msgs) > limit {
+		msgs = msgs[len(msgs)-limit:]
+	}
+	return msgs, nil
+}