Watch the have bucket only where the node's grant allows, so a node composing itself is not refused by the bus (issue 1126)

The fold's watch of every have key ('>') was refused (permissions violation on
CONSUMER.CREATE KV_node-engine_have), and every self-composing agent stopped
after the seed. The composer now watches '*.node' (records) and '<node>.>' (its
own haves), as buscompose grants a node; the shadow watches '<node>.>' too. The
selfcompose tests check every watch and get against PermissionsFor(KindNode),
and the agent's integration tests run the agent as the node under that grant.

internal/selfcompose/selfcompose_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 	"time"
 
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/compose"
 	"git.novox.be/novox/mesh-sdk/go/compose/frombus"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
@@ -18,41 +19,95 @@ import (
 
 const lemurs = `{"module":"lemurs","version":"1","capabilities":["systemd"],"resources":[{"id":"service","type":"service","unit":"lemurs.service","state":"running","boot":"enabled"}]}`
 
-// fakeBus is the buckets the composer watches, each a channel a test writes updates to, and the keys Get reads.
+// fakeBus is the buckets the composer watches, each watch a channel that gets the updates a test writes to its bucket
+// whose key its pattern matches, as the bus's own watches do, and the keys Get reads. It keeps every watch and get
+// made, so a test checks each against the node's grant.
 type fakeBus struct {
-	mu    sync.Mutex
-	chans map[string]chan agent.Update
-	kv    map[string][]byte // bucket/key
-	said  []string
+	mu      sync.Mutex
+	watches []patternWatch
+	kv      map[string][]byte // bucket/key
+	said    []string
+	reads   [][2]string // bucket, pattern or key: every watch and get
 }
 
 func newFakeBus() *fakeBus {
-	return &fakeBus{chans: map[string]chan agent.Update{}, kv: map[string][]byte{}}
-}
-
-func (b *fakeBus) ch(bucket string) chan agent.Update {
-	b.mu.Lock()
-	defer b.mu.Unlock()
-	if b.chans[bucket] == nil {
-		b.chans[bucket] = make(chan agent.Update, 16)
-	}
-	return b.chans[bucket]
+	return &fakeBus{kv: map[string][]byte{}}
 }
 
 func (b *fakeBus) env() Env {
 	return Env{Node: "n1",
-		Watch: func(_ context.Context, bucket, _ string) (<-chan agent.Update, error) { return b.ch(bucket), nil },
+		Watch: func(_ context.Context, bucket, pattern string) (<-chan agent.Update, error) {
+			b.mu.Lock()
+			defer b.mu.Unlock()
+			w := patternWatch{bucket: bucket, pattern: pattern, ch: make(chan agent.Update, 64)}
+			b.watches = append(b.watches, w)
+			b.reads = append(b.reads, [2]string{bucket, pattern})
+			return w.ch, nil
+		},
 		Get: func(_ context.Context, bucket, key string) ([]byte, error) {
 			b.mu.Lock()
 			defer b.mu.Unlock()
+			b.reads = append(b.reads, [2]string{bucket, key})
 			return b.kv[bucket+"/"+key], nil
 		},
 		Say: func(s string) { b.mu.Lock(); b.said = append(b.said, s); b.mu.Unlock() }}
 }
 
+// send gives u to every watch of bucket whose pattern matches its key; Caught to every watch of bucket.
+func (b *fakeBus) send(bucket string, u agent.Update) {
+	b.mu.Lock()
+	ws := append([]patternWatch(nil), b.watches...)
+	b.mu.Unlock()
+	for _, w := range ws {
+		if w.bucket == bucket && (u.Caught || matches(w.pattern, u.Key)) {
+			w.ch <- u
+		}
+	}
+}
+
 func (b *fakeBus) put(t *testing.T, bucket, key string, value []byte) {
 	t.Helper()
-	b.ch(bucket) <- agent.Update{Key: key, Value: value}
+	b.send(bucket, agent.Update{Key: key, Value: value})
+}
+
+// grantAllows says whether the node's grant (buscompose.PermissionsFor, KindNode) lets it watch or read pattern of
+// bucket: the consumer a watch or a get makes (`$JS.API.CONSUMER.CREATE.KV_<bucket>.<name>.$KV.<bucket>.<pattern>`)
+// and the stream's information, matched as the bus matches a permission against a subject.
+func grantAllows(t *testing.T, node, bucket, pattern string) bool {
+	t.Helper()
+	perms, err := buscompose.PermissionsFor(buscompose.Principal{Kind: buscompose.KindNode, Node: node})
+	if err != nil {
+		t.Fatal(err)
+	}
+	allowed := func(subject string) bool {
+		for _, deny := range perms.PublishDeny {
+			if subjectMatches(deny, subject) {
+				return false
+			}
+		}
+		for _, p := range perms.Publish {
+			if subjectMatches(p, subject) {
+				return true
+			}
+		}
+		return false
+	}
+	stream := "KV_" + bucket
+	return allowed("$JS.API.STREAM.INFO."+stream) && allowed("$JS.API.CONSUMER.CREATE."+stream+".c1.$KV."+bucket+"."+pattern)
+}
+
+// subjectMatches is the bus's match of a permission against a subject: `*` any one token, `>` one or more to the end.
+func subjectMatches(permission, subject string) bool {
+	p, s := strings.Split(permission, "."), strings.Split(subject, ".")
+	for i, tok := range p {
+		if tok == ">" {
+			return len(s) > i
+		}
+		if i >= len(s) || (tok != "*" && tok != s[i]) {
+			return false
+		}
+	}
+	return len(p) == len(s)
 }
 
 func next(t *testing.T, out <-chan agent.Update) agent.Update {
@@ -135,7 +190,7 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 	b.put(t, delivery.AssignerWantsBucket, "want.n1.lemurs", want)
 	b.put(t, delivery.AssignerWantsBucket, "want.n1.node", nodeWant)
 	for _, bucket := range []string{delivery.AssignerWantsBucket, delivery.PlacementBucket, delivery.HaveBucket, delivery.ModulesBucket, ResolvedBucket} {
-		b.ch(bucket) <- agent.Update{Caught: true}
+		b.send(bucket, agent.Update{Caught: true})
 	}
 	got := map[string]bool{}
 	var own delivery.Composed
@@ -163,6 +218,15 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 	if !strings.Contains(strings.Join(ownText, " "), `"id":"oldie.service"`) {
 		t.Errorf("the node's own composition, composed before anything was applied, lacks oldie: %v", ownText)
 	}
+	// Issue 1126, 2026-10-27 09:21: every watch and get the composer makes is one the node's grant allows; a watch of
+	// every have key (`>`) was refused by the bus and stopped every node agent.
+	b.mu.Lock()
+	for _, r := range b.reads {
+		if !grantAllows(t, "n1", r[0], r[1]) {
+			t.Errorf("the composer reads %s of %s, which the node's grant does not allow", r[1], r[0])
+		}
+	}
+	b.mu.Unlock()
 	lemursKey, _ := delivery.ComposedKey("n1", "lemurs", fp)
 	nodeKey, _ := delivery.ComposedNodeKey("n1")
 	if !got[lemursKey] || !got[nodeKey] || len(got) != 2 {
@@ -424,6 +488,21 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 		}
 	}
 	waitFor("every group answered", func(a map[string]delivery.CandidateAnswer) bool { return len(a) == 4 })
+	// Every watch and get the shadow makes is one the node's grant allows (issue 1126, 2026-10-27 09:21).
+	sb.mu.Lock()
+	for _, w := range sb.watches {
+		if !grantAllows(t, "n1", w.bucket, w.pattern) {
+			t.Errorf("the shadow watches %s of %s, which the node's grant does not allow", w.pattern, w.bucket)
+		}
+	}
+	sb.mu.Unlock()
+	readOnly.mu.Lock()
+	for _, r := range readOnly.reads {
+		if !grantAllows(t, "n1", r[0], r[1]) {
+			t.Errorf("the shadow reads %s of %s, which the node's grant does not allow", r[1], r[0])
+		}
+	}
+	readOnly.mu.Unlock()
 	for group, want := range map[string]func(delivery.CandidateAnswer) bool{
 		"same": func(a delivery.CandidateAnswer) bool {
 			return a.Verdict == delivery.CandidateSame && a.Head == "h-same" && a.Revision == 3 && len(a.Same) == 2