refactor(init): construct the LocalStack adapter inside the interop server

The adapter was hoisted into main.go "so it can be shared with the
interop server", but nothing in main.go uses it after the constructor
call — main reaches the adapter through interopServer.localStackAdapter.
Revert to in-constructor creation and drop the extra parameter. Also fix
a stale comment in events.go referencing a CustomInteropServer.onDemand
field that does not exist.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: joe4dev

cmd/localstack/custom_interop.go

@@ -99,13 +99,16 @@ func (l *LocalStackAdapter) SendResult(invokeId string, body []byte, isError boo
 	return l.post(endpoint, body)
 }
 
-func NewCustomInteropServer(lsOpts *LsOpts, adapter *LocalStackAdapter, delegate interop.Server, logCollector *LogCollector, eventsAPI *LocalStackEventsAPI) (server *CustomInteropServer) {
+func NewCustomInteropServer(lsOpts *LsOpts, delegate interop.Server, logCollector *LogCollector, eventsAPI *LocalStackEventsAPI) (server *CustomInteropServer) {
 	server = &CustomInteropServer{
-		delegate:          delegate.(*rapidcore.Server),
-		port:              lsOpts.InteropPort,
-		upstreamEndpoint:  lsOpts.RuntimeEndpoint,
-		localStackAdapter: adapter,
-		eventsAPI:         eventsAPI,
+		delegate:         delegate.(*rapidcore.Server),
+		port:             lsOpts.InteropPort,
+		upstreamEndpoint: lsOpts.RuntimeEndpoint,
+		localStackAdapter: &LocalStackAdapter{
+			UpstreamEndpoint: lsOpts.RuntimeEndpoint,
+			RuntimeId:        lsOpts.RuntimeId,
+		},
+		eventsAPI: eventsAPI,
 	}
 
 	// TODO: extract this

cmd/localstack/events.go

@@ -36,9 +36,9 @@ type LocalStackEventsAPI struct {
 	// never calls — i.e. unbounded memory growth in warm environments.
 	lambdatelemetry.NoOpEventsAPI
 	logCollector *LogCollector
-	// onDemand mirrors CustomInteropServer.onDemand: only on-demand functions report the
-	// cold-start init duration in their first invocation's REPORT line (AWS omits it for
-	// provisioned-concurrency and Managed Instances invokes).
+	// onDemand is true for on-demand functions (see the onDemand classification in main.go):
+	// only those report the cold-start init duration in their first invocation's REPORT line
+	// (AWS omits it for provisioned-concurrency and Managed Instances invokes).
 	onDemand bool
 
 	mu sync.Mutex

cmd/localstack/main.go

@@ -195,12 +195,6 @@ func main() {
 	localStackLogsEgressApi := NewLocalStackLogsEgressAPI(logCollector)
 	tracer := NewLocalStackTracer()
 
-	// Create LocalStack adapter upfront so it can be shared with the interop server
-	lsAdapter := &LocalStackAdapter{
-		UpstreamEndpoint: lsOpts.RuntimeEndpoint,
-		RuntimeId:        lsOpts.RuntimeId,
-	}
-
 	// onDemand is true for on-demand functions, where AWS folds a failed cold-start init into
 	// the first invocation (suppressed init). For these we do NOT report init failures via
 	// /status/error; instead we signal ready and let the first invoke surface the error with
@@ -250,7 +244,7 @@ func main() {
 	runDaemon(d) // async
 
 	defaultInterop := sandbox.DefaultInteropServer()
-	interopServer := NewCustomInteropServer(lsOpts, lsAdapter, defaultInterop, logCollector, lsEventsAPI)
+	interopServer := NewCustomInteropServer(lsOpts, defaultInterop, logCollector, lsEventsAPI)
 	sandbox.SetInteropServer(interopServer)
 	if len(handler) > 0 {
 		sandbox.SetHandler(handler)