H-15: the apply guard and the yields read the node-engine's module from the entry claiming its seat

The module is the one whose catalog entry claims node-engine, else the one this node heard run the build its own
fingerprint names; no name is fixed in the guard or in the compose.

Builds: design 47 G §364, §527, §428

Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ

internal/selfcompose/selfcompose.go

@@ -33,6 +33,7 @@ import (
 	"github.com/novox/mesh-host/internal/compositions"
 	engcomp "github.com/novox/mesh-host/internal/compositions"
 	"maps"
+	"os"
 	"reflect"
 	"slices"
 	"sort"
@@ -180,6 +181,8 @@ type Composer struct {
 	// node's own consumer (NoteRunning), under mu; heardRead is whether the first read of the stream ended (RunningRead).
 	heard     map[string]map[string]heardRun
 	heardRead bool
+	// engine is the node-engine's own module as the last composing of the node's input found it (Scope.Engine), under mu.
+	engine string
 	// rehand asks for a pass that hands again what the agent waits for (Waiting).
 	rehand chan struct{}
 	// sealedOwn is each own secret's sealed value as first handed, by module/name and generation: a value sealed again
@@ -1002,7 +1005,7 @@ func (c *Composer) compose(ctx context.Context) []agent.Update {
 	var keptMu sync.Mutex
 	var holds map[string]compose.Hold
 	fromManifest := map[string]string{} // by module, why it is composed from the indexer's manifest and not a build
-	scope := frombus.Scope{Node: c.env.Node, KeptAt: kept, InOwn: inOwn, Running: running, Heard: c.heardNow(), Kept: func(module, words string) {
+	scope := frombus.Scope{Node: c.env.Node, KeptAt: kept, InOwn: inOwn, Running: running, Heard: c.heardNow(), Engine: c.noteEngine, OwnFingerprint: os.Getenv(engcomp.FingerprintVar), Kept: func(module, words string) {
 		keptMu.Lock()
 		defer keptMu.Unlock()
 		if !slices.Contains(keptRuns[module], words) {
@@ -2351,3 +2354,20 @@ func (c *Composer) heardNow() map[string]map[string]frombus.Heard {
 	}
 	return out
 }
+
+// noteEngine keeps the node-engine's own module a composing of the node's input found; one that finds none changes nothing.
+func (c *Composer) noteEngine(module string) {
+	if module == "" {
+		return
+	}
+	c.mu.Lock()
+	c.engine = module
+	c.mu.Unlock()
+}
+
+// EngineModule is the node-engine's own module (design 47 G §527), for the apply guard; "" until a composing found it.
+func (c *Composer) EngineModule() string {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.engine
+}