wire: make WaitForReply actually work; export FromSignal

WaitForReply set the x-reply-inbox header but never msg.Reply — and
the receive side (transport.handleIncoming) responds via m.RespondMsg,
which publishes to the native Reply field and never reads the header.
Every WaitForReply call timed out even on successful delivery. Set
msg.Reply to the inbox; the header stays for observability.

Also export wire.FromSignal and alias runner.FromSignal to it, so
external publishers (the platform's publish-signal path) stop
hardcoding the "signal" literal that the runner's raw-payload check
depends on.

Publisher-side only — deployed modules already reply natively, no
module re-tags needed.

Author: tpoxa

internal/scheduler/runner/runner.go

@@ -27,6 +27,7 @@ import (
 	"github.com/tiny-systems/module/pkg/resource"
 	"github.com/tiny-systems/module/pkg/schema"
 	"github.com/tiny-systems/module/pkg/utils"
+	"github.com/tiny-systems/module/pkg/wire"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/metric"
@@ -72,7 +73,7 @@ type Runner struct {
 	reconcileDebouncer *ReconcileDebouncer
 
 	// pendingNodeUpdaters accumulates metadata update functions during debounce window
-	pendingNodeUpdaters    []func(*v1alpha1.TinyNode) error
+	pendingNodeUpdaters     []func(*v1alpha1.TinyNode) error
 	pendingNodeUpdatersLock *sync.Mutex
 
 	// activeEdges tracks busy edge timestamps for the single gauge callback
@@ -113,7 +114,9 @@ type snapshotRefresher interface {
 }
 
 const (
-	FromSignal = "signal"
+	// FromSignal aliases wire.FromSignal so external publishers and
+	// the runner's signal check can never drift apart.
+	FromSignal = wire.FromSignal
 )
 
 func NewRunner(component m.Component) *Runner {
@@ -1139,8 +1142,8 @@ func (c *Runner) clearGauge(edgeID string) {
 
 // retryState holds the live retry counter and latest transient error for one edge.
 type retryState struct {
-	count    int64
-	lastErr  string
+	count   int64
+	lastErr string
 }
 
 func (c *Runner) ensureRetryGauge() {

pkg/wire/publish.go

@@ -41,6 +41,16 @@ const (
 
 const subjectPrefix = "tinymodule"
 
+// FromSignal is the Options.From value that marks a message as an
+// external signal (dashboard Send, MCP send_signal, debug). The
+// runner unmarshals the raw payload into the port struct ONLY for
+// signal-originated messages — any other From (including empty)
+// makes it fall back to edge-config evaluation or the port's default
+// configuration, silently discarding the payload. Mirrors
+// runner.FromSignal, which lives in internal/ and can't be imported
+// by external publishers.
+const FromSignal = "signal"
+
 // SubjectFor returns the business-hop NATS subject for a given
 // module. Senders publish here for edge-driven hops; the module's
 // queue-group consumer load-balances among pods.
@@ -134,6 +144,13 @@ func Publish(ctx context.Context, nc *nats.Conn, targetNode, port string, data [
 	}
 	defer func() { _ = sub.Unsubscribe() }()
 	msg.Header.Set(HeaderReplyInbox, inbox)
+	// The receive side (transport.handleIncoming) replies with
+	// m.RespondMsg, which publishes to the NATS-native Reply field —
+	// it never reads the x-reply-inbox header. Without msg.Reply set
+	// here every WaitForReply call timed out even on successful
+	// delivery. Keep the header for observability, but the native
+	// Reply field is what makes the round-trip work.
+	msg.Reply = inbox
 
 	if err := nc.PublishMsg(msg); err != nil {
 		return nil, fmt.Errorf("publish: %w", err)