fix: clean up leaked contexts on SSE disconnect and add orphan reaper

When clients disconnect without beforeunload firing (network drops,
mobile kills, crashes), contexts leaked in the registry permanently.

- Extract cleanupCtx helper for dispose/unregister sequence
- Call cleanupCtx on SSE disconnect (sse.Context().Done())
- Add background reaper for contexts where SSE never connected
- Add ContextTTL config option (default 30s, negative disables)
- Fix inverted condition in devModeRemovePersisted

configuration.go

@@ -1,6 +1,8 @@
 package via
 
 import (
+	"time"
+
 	"github.com/alexedwards/scs/v2"
 	"github.com/rs/zerolog"
 )
@@ -54,4 +56,9 @@ type Options struct {
 	// PubSub enables publish/subscribe messaging. Use vianats.New() for an
 	// embedded NATS backend, or supply any PubSub implementation.
 	PubSub PubSub
+
+	// ContextTTL is the maximum time a context may exist without an SSE
+	// connection before the background reaper disposes it.
+	// Default: 30s. Negative value disables the reaper.
+	ContextTTL time.Duration
 }

context.go

@@ -8,6 +8,7 @@ import (
 	"maps"
 	"reflect"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ryanhamamura/via/h"
@@ -33,6 +34,8 @@ type Context struct {
 	subscriptions     []Subscription
 	subsMu            sync.Mutex
 	disposeOnce       sync.Once
+	createdAt         time.Time
+	sseConnected      atomic.Bool
 }
 
 // View defines the UI rendered by this context.
@@ -481,5 +484,6 @@ func newContext(id string, route string, v *V) *Context {
 		signals:           new(sync.Map),
 		patchChan:         make(chan patch, 1),
 		ctxDisposedChan:   make(chan struct{}, 1),
+		createdAt:         time.Now(),
 	}
 }

internal/examples/nats-chatroom/main.go

@@ -2,13 +2,11 @@ package main
 
 import (
 	"context"
-	"encoding/json"
 	"log"
 	"math/rand"
 	"sync"
 	"time"
 
-	"github.com/nats-io/nats.go"
 	"github.com/ryanhamamura/via"
 	"github.com/ryanhamamura/via/h"
 	"github.com/ryanhamamura/via/vianats"
@@ -46,15 +44,15 @@ func main() {
 	}
 	defer ps.Close()
 
-	// Create JetStream stream for message durability
+	err = vianats.EnsureStream(ps, vianats.StreamConfig{
-	js := ps.JetStream()
+		Name:     "CHAT",
-	js.AddStream(&nats.StreamConfig{
+		Subjects: []string{"chat.>"},
-		Name:      "CHAT",
+		MaxMsgs:  1000,
-		Subjects:  []string{"chat.>"},
+		MaxAge:   24 * time.Hour,
-		Retention: nats.LimitsPolicy,
-		MaxMsgs:   1000,
-		MaxAge:    24 * time.Hour,
 	})
+	if err != nil {
+		log.Fatalf("Failed to ensure stream: %v", err)
+	}
 
 	v := via.New()
 	v.Config(via.Options{
@@ -147,30 +145,14 @@ func main() {
 				currentSub.Unsubscribe()
 			}
 
-			// Replay history from JetStream before subscribing for real-time
 			subject := "chat.room." + room
-			if hist, err := js.SubscribeSync(subject, nats.DeliverAll(), nats.OrderedConsumer()); err == nil {
+
-				for {
+			// Replay history from JetStream
-					msg, err := hist.NextMsg(200 * time.Millisecond)
+			if hist, err := vianats.ReplayHistory[ChatMessage](ps, subject, 50); err == nil {
-					if err != nil {
+				messages = hist
-						break
-					}
-					var chatMsg ChatMessage
-					if json.Unmarshal(msg.Data, &chatMsg) == nil {
-						messages = append(messages, chatMsg)
-					}
-				}
-				hist.Unsubscribe()
-				if len(messages) > 50 {
-					messages = messages[len(messages)-50:]
-				}
 			}
 
-			sub, _ := c.Subscribe(subject, func(data []byte) {
+			sub, _ := via.Subscribe(c, subject, func(msg ChatMessage) {
-				var msg ChatMessage
-				if err := json.Unmarshal(data, &msg); err != nil {
-					return
-				}
 				messagesMu.Lock()
 				messages = append(messages, msg)
 				if len(messages) > 50 {
@@ -203,12 +185,11 @@ func main() {
 			}
 			statement.SetValue("")
 
-			data, _ := json.Marshal(ChatMessage{
+			via.Publish(c, "chat.room."+currentRoom, ChatMessage{
 				User:    currentUser,
 				Message: msg,
 				Time:    time.Now().UnixMilli(),
 			})
-			c.Publish("chat.room."+currentRoom, data)
 		})
 
 		c.View(func() h.H {

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()
+}

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

@@ -36,20 +36,21 @@ var datastarJS []byte
 // V is the root application.
 // It manages page routing, user sessions, and SSE connections for live updates.
 type V struct {
-	cfg                       Options
+	cfg                  Options
-	mux                       *http.ServeMux
+	mux                  *http.ServeMux
-	server                    *http.Server
+	server               *http.Server
-	logger                    zerolog.Logger
+	logger               zerolog.Logger
-	contextRegistry           map[string]*Context
+	contextRegistry      map[string]*Context
-	contextRegistryMutex      sync.RWMutex
+	contextRegistryMutex sync.RWMutex
-	documentHeadIncludes      []h.H
+	documentHeadIncludes []h.H
-	documentFootIncludes      []h.H
+	documentFootIncludes []h.H
-	devModePageInitFnMap      map[string]func(*Context)
+	devModePageInitFnMap map[string]func(*Context)
-	sessionManager  *scs.SessionManager
+	sessionManager       *scs.SessionManager
-	pubsub          PubSub
+	pubsub               PubSub
-	datastarPath    string
+	datastarPath         string
-	datastarContent []byte
+	datastarContent      []byte
-	datastarOnce    sync.Once
+	datastarOnce         sync.Once
+	reaperStop           chan struct{}
 }
 
 func (v *V) logEvent(evt *zerolog.Event, c *Context) *zerolog.Event {
@@ -127,6 +128,9 @@ func (v *V) Config(cfg Options) {
 	if cfg.PubSub != nil {
 		v.pubsub = cfg.PubSub
 	}
+	if cfg.ContextTTL != 0 {
+		v.cfg.ContextTTL = cfg.ContextTTL
+	}
 }
 
 // AppendToHead appends the given h.H nodes to the head of the base HTML document.
@@ -238,6 +242,14 @@ func (v *V) currSessionNum() int {
 	return len(v.contextRegistry)
 }
 
+func (v *V) cleanupCtx(c *Context) {
+	c.dispose()
+	if v.cfg.DevMode {
+		v.devModeRemovePersisted(c)
+	}
+	v.unregisterCtx(c)
+}
+
 func (v *V) unregisterCtx(c *Context) {
 	if c.id == "" {
 		v.logErr(c, "unregister ctx failed: ctx contains empty id")
@@ -259,6 +271,50 @@ func (v *V) getCtx(id string) (*Context, error) {
 	return nil, fmt.Errorf("ctx '%s' not found", id)
 }
 
+func (v *V) startReaper() {
+	ttl := v.cfg.ContextTTL
+	if ttl < 0 {
+		return
+	}
+	if ttl == 0 {
+		ttl = 30 * time.Second
+	}
+	interval := ttl / 3
+	if interval < 5*time.Second {
+		interval = 5 * time.Second
+	}
+	v.reaperStop = make(chan struct{})
+	go func() {
+		ticker := time.NewTicker(interval)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-v.reaperStop:
+				return
+			case <-ticker.C:
+				v.reapOrphanedContexts(ttl)
+			}
+		}
+	}()
+}
+
+func (v *V) reapOrphanedContexts(ttl time.Duration) {
+	now := time.Now()
+	v.contextRegistryMutex.RLock()
+	var orphans []*Context
+	for _, c := range v.contextRegistry {
+		if !c.sseConnected.Load() && now.Sub(c.createdAt) > ttl {
+			orphans = append(orphans, c)
+		}
+	}
+	v.contextRegistryMutex.RUnlock()
+
+	for _, c := range orphans {
+		v.logInfo(c, "reaping orphaned context (no SSE connection after %s)", ttl)
+		v.cleanupCtx(c)
+	}
+}
+
 // 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() {
@@ -271,6 +327,8 @@ func (v *V) Start() {
 		Handler: handler,
 	}
 
+	v.startReaper()
+
 	errCh := make(chan error, 1)
 	go func() {
 		errCh <- v.server.ListenAndServe()
@@ -301,6 +359,9 @@ func (v *V) Shutdown() {
 }
 
 func (v *V) shutdown() {
+	if v.reaperStop != nil {
+		close(v.reaperStop)
+	}
 	v.logInfo(nil, "draining all contexts")
 	v.drainAllContexts()
 
@@ -400,10 +461,7 @@ func (v *V) devModeRemovePersisted(c *Context) {
 	}
 	file.Close()
 
-	// remove ctx to persisted list
+	delete(ctxRegMap, c.id)
-	if _, ok := ctxRegMap[c.id]; !ok {
-		delete(ctxRegMap, c.id)
-	}
 
 	// write persisted list to file
 	file, err = os.Create(p)
@@ -507,6 +565,7 @@ func New() *V {
 		// use last-event-id to tell if request is a sse reconnect
 		sse.Send(datastar.EventTypePatchElements, []string{}, datastar.WithSSEEventId("via"))
 
+		c.sseConnected.Store(true)
 		v.logDebug(c, "SSE connection established")
 
 		go func() {
@@ -517,6 +576,7 @@ func New() *V {
 			select {
 			case <-sse.Context().Done():
 				v.logDebug(c, "SSE connection ended")
+				v.cleanupCtx(c)
 				return
 			case <-c.ctxDisposedChan:
 				v.logDebug(c, "context disposed, closing SSE")
@@ -603,12 +663,8 @@ func New() *V {
 			v.logErr(c, "failed to handle session close: %v", err)
 			return
 		}
-		c.dispose()
 		v.logDebug(c, "session close event triggered")
-		if v.cfg.DevMode {
+		v.cleanupCtx(c)
-			v.devModeRemovePersisted(c)
-		}
-		v.unregisterCtx(c)
 	})
 	return v
 }

via_test.go

@@ -1,9 +1,13 @@
 package via
 
 import (
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"os"
+	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/ryanhamamura/via/h"
 	"github.com/stretchr/testify/assert"
@@ -235,3 +239,93 @@ func TestPage_PanicsOnNoView(t *testing.T) {
 		v.Page("/", func(c *Context) {})
 	})
 }
+
+func TestReaperCleansOrphanedContexts(t *testing.T) {
+	v := New()
+	c := newContext("orphan-1", "/", v)
+	c.createdAt = time.Now().Add(-time.Minute) // created 1 min ago
+	v.registerCtx(c)
+
+	_, err := v.getCtx("orphan-1")
+	assert.NoError(t, err)
+
+	v.reapOrphanedContexts(10 * time.Second)
+
+	_, err = v.getCtx("orphan-1")
+	assert.Error(t, err, "orphaned context should have been reaped")
+}
+
+func TestReaperIgnoresConnectedContexts(t *testing.T) {
+	v := New()
+	c := newContext("connected-1", "/", v)
+	c.createdAt = time.Now().Add(-time.Minute)
+	c.sseConnected.Store(true)
+	v.registerCtx(c)
+
+	v.reapOrphanedContexts(10 * time.Second)
+
+	_, err := v.getCtx("connected-1")
+	assert.NoError(t, err, "connected context should survive reaping")
+}
+
+func TestReaperDisabledWithNegativeTTL(t *testing.T) {
+	v := New()
+	v.cfg.ContextTTL = -1
+	v.startReaper()
+	assert.Nil(t, v.reaperStop, "reaper should not start with negative TTL")
+}
+
+func TestCleanupCtxIdempotent(t *testing.T) {
+	v := New()
+	c := newContext("idempotent-1", "/", v)
+	v.registerCtx(c)
+
+	assert.NotPanics(t, func() {
+		v.cleanupCtx(c)
+		v.cleanupCtx(c)
+	})
+
+	_, err := v.getCtx("idempotent-1")
+	assert.Error(t, err, "context should be removed after cleanup")
+}
+
+func TestDevModeRemovePersistedFix(t *testing.T) {
+	v := New()
+	v.cfg.DevMode = true
+
+	dir := filepath.Join(t.TempDir(), ".via", "devmode")
+	p := filepath.Join(dir, "ctx.json")
+	assert.NoError(t, os.MkdirAll(dir, 0755))
+
+	// Write a persisted context
+	ctxRegMap := map[string]string{"test-ctx-1": "/"}
+	f, err := os.Create(p)
+	assert.NoError(t, err)
+	assert.NoError(t, json.NewEncoder(f).Encode(ctxRegMap))
+	f.Close()
+
+	// Patch devModeRemovePersisted to use our temp path by calling it
+	// directly — we need to override the path. Instead, test via the
+	// actual function by temporarily changing the working dir.
+	origDir, _ := os.Getwd()
+	assert.NoError(t, os.Chdir(t.TempDir()))
+	defer os.Chdir(origDir)
+
+	// Re-create the structure in the temp dir
+	assert.NoError(t, os.MkdirAll(filepath.Join(".via", "devmode"), 0755))
+	p2 := filepath.Join(".via", "devmode", "ctx.json")
+	f2, _ := os.Create(p2)
+	json.NewEncoder(f2).Encode(map[string]string{"test-ctx-1": "/"})
+	f2.Close()
+
+	c := newContext("test-ctx-1", "/", v)
+	v.devModeRemovePersisted(c)
+
+	// Read back and verify
+	f3, err := os.Open(p2)
+	assert.NoError(t, err)
+	defer f3.Close()
+	var result map[string]string
+	assert.NoError(t, json.NewDecoder(f3).Decode(&result))
+	assert.Empty(t, result, "persisted context should be removed")
+}

vianats/vianats.go

@@ -4,7 +4,9 @@ package vianats
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"time"
 
 	"github.com/delaneyj/toolbelt/embeddednats"
 	"github.com/nats-io/nats.go"
@@ -76,3 +78,50 @@ func (n *NATS) Conn() *nats.Conn {
 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
+}