diff --git a/go/buscompose/buscompose_test.go b/go/buscompose/buscompose_test.go
index 0138721..bd56f70 100644
--- a/go/buscompose/buscompose_test.go
+++ b/go/buscompose/buscompose_test.go
@@ -41,6 +41,12 @@ var createdAdvisory = regexp.MustCompile(`"\$JS\.EVENT\.ADVISORY\.STREAM\.CREATE
 // write.
 func beyondTheControllers(user string) map[string]bool {
 	out := map[string]bool{}
+	// The self-check's runtime asks who answers (D-root, D3).
+	if strings.HasSuffix(user, "."+SelfCheckModule) {
+		for _, s := range discovering() {
+			out[s] = true
+		}
+	}
 	if strings.HasSuffix(user, "."+WatchmanModule) {
 		for _, s := range append(WatchmanDeadLetterGrants(nil), WatchmanHears()...) {
 			out[s] = true
@@ -659,7 +665,7 @@ func healthChecks(t *testing.T) {
 		"provisioner.a": {"$JS.API.DIRECT.GET.KV_mesh-provisioner_plans.$KV.mesh-provisioner_plans.a.keycloak",
 			"$JS.API.CONSUMER.CREATE.KV_mesh-provisioner_plans.c1.$KV.mesh-provisioner_plans.a.keycloak"},
 		// ADR 0571 clause 3: restic's bundle writes each item's last good night as its own state; the self-check reads it.
-		"a.mesh-self-check": {"$JS.API.DIRECT.GET.KV_restic_good.$KV.restic_good.a.pg.data",
+		"a.mesh-self-check": {"$JS.API.DIRECT.GET.KV_restic_good.$KV.restic_good.a.pg.data", "$SRV.INFO.node-tools", "$SRV.PING",
 			"$JS.API.DIRECT.GET.KV_mesh-grants_withheld.$KV.mesh-grants_withheld." + WithheldKey(Withheld{Node: "a", Module: "reader", Stream: "MAIL"})},
 		"a.mesh-grants": {"$KV.mesh-grants_withheld.reader.mail.a"},
 		"a.restic": {"$JS.API.DIRECT.GET.KV_disk-load_readings.$KV.disk-load_readings.a.pg.data", "$KV.restic_good.a.pg.data",
@@ -688,7 +694,7 @@ func healthChecks(t *testing.T) {
 		"a.mesh-vault": {"$KV.mesh-provisioner_provisions.a.keycloak.postgres-database", "$KV.mesh-provisioner_plans.a.keycloak",
 			"mesh.seat.mesh-artifact-sweep.event.artifacts-gone"},
 		// Each writes its own state alone, and these users are composed.
-		"a.disk-load":             {"$KV.restic_good.a.pg.data"},
+		"a.disk-load":             {"$KV.restic_good.a.pg.data", "$SRV.INFO", "$SRV.PING.node-tools"},
 		"a.mesh-delivery-builder": {"$KV.disk-load_readings.a.pg.data"},
 		// Another machine's plans are not its to read; no client writes or reads the needs any more.
 		"provisioner.a": {"$JS.API.DIRECT.GET.KV_mesh-provisioner_plans.$KV.mesh-provisioner_plans.b.keycloak",
diff --git a/go/buscompose/health_grants.go b/go/buscompose/health_grants.go
index e31a935..916853d 100644
--- a/go/buscompose/health_grants.go
+++ b/go/buscompose/health_grants.go
@@ -170,3 +170,6 @@ func keepsDeadLetters(p Principal, pattern string) bool {
 	return isController(p, pattern) ||
 		(p.Kind == KindModule && p.Module == WatchmanModule && pattern == deadLetterPrefix+">")
 }
+
+// SelfCheckModule is the module holding the seat mesh-self-check, whose runtime asks the bus who answers (D-root, D3).
+const SelfCheckModule = health.SelfCheckModule
diff --git a/go/buscompose/nats.go b/go/buscompose/nats.go
index 61bdfa9..64b6adf 100644
--- a/go/buscompose/nats.go
+++ b/go/buscompose/nats.go
@@ -1014,6 +1014,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 			// And the words its watchdogs hear (ADR 0564 clause 4, Limits 3, 11).
 			sub = append(sub, WatchmanHears()...)
 		}
+		// The self-check asks who answers a verb (D-root, D3): its runtime, on the self-check's own account (runs-as),
+		// asks the bus's discovery, its replies to its own inbox; no other module's account may.
+		if p.Module == SelfCheckModule {
+			pub = append(pub, discovering()...)
+		}
 		// The grants part alone publishes the modules' memberships into the assignments stream (novox/hq ADR 0547 §5;
 		// the operator, 2026-10-25 22:31): one per subject, `mesh.assignment.<node>.<module>`, reading the last one of each
 		// first so it publishes only what changed, and no stream it defines.
diff --git a/go/discover.go b/go/discover.go
new file mode 100644
index 0000000..c7e5f90
--- /dev/null
+++ b/go/discover.go
@@ -0,0 +1,48 @@
+package stdio
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+)
+
+// **Who answers a verb, asked by the bus's discovery** (D-root and D3 of the seat mesh-self-check; issue 1955): the
+// runtime asks the services protocol on the account it runs as (ADR 0197) and answers each machine and module that
+// says it serves the verb. The bundle never asks the bus itself.
+
+// Answerer is one module on one machine that answers a verb.
+type Answerer struct {
+	Machine string `json:"machine"`
+	Module  string `json:"module"`
+}
+
+const discoverTimeout = 10 * time.Second
+
+// Discover is every module that answers verb (`<seat>.<verb>` or `<module>.<tool>`), on node when one is named: runtime
+// verb `mesh/discover {verb, node?}`, answered as a list. None answering is an empty list and no error; an error is a
+// question that could not be asked.
+func Discover(verb, node string) ([]Answerer, error) {
+	if verb == "" {
+		return nil, fmt.Errorf("discover names the verb it asks about")
+	}
+	c, err := live()
+	if err != nil {
+		return nil, err
+	}
+	params := map[string]any{"verb": verb}
+	if node != "" {
+		params["node"] = node
+	}
+	raw, err := c.ask("mesh/discover", params, discoverTimeout)
+	if err != nil {
+		return nil, err
+	}
+	out := []Answerer{}
+	if len(raw) == 0 || string(raw) == "null" {
+		return out, nil
+	}
+	if err := json.Unmarshal(raw, &out); err != nil {
+		return nil, fmt.Errorf("the runtime's answer to discover is not readable: %w", err)
+	}
+	return out, nil
+}
diff --git a/go/log_test.go b/go/log_test.go
index 98bba28..a0f7bbc 100644
--- a/go/log_test.go
+++ b/go/log_test.go
@@ -154,6 +154,17 @@ func logging(t *testing.T, r *logRuntime, run func() (any, error)) map[string]an
 			if json.Unmarshal(lines.Bytes(), &m) != nil {
 				continue
 			}
+			if m.Method == "mesh/discover" {
+				// Who answers: one module on ace, none on any other machine named.
+				var p struct{ Verb, Node string }
+				_ = json.Unmarshal(m.Params, &p)
+				var result any = []map[string]string{{"machine": "ace", "module": "node-tools"}}
+				if p.Node != "" && p.Node != "ace" {
+					result = nil
+				}
+				send(map[string]any{"id": m.ID, "result": result})
+				continue
+			}
 			if strings.HasPrefix(m.Method, "mesh/log.") {
 				go func(m message) {
 					a := r.answer(m)
@@ -214,6 +225,7 @@ func TestABundleKeepsALogThroughTheRuntime(t *testing.T) {
 		narrowed, since      *LogPage
 		newest               []LogEntry
 		watched              *LogEntry
+		found, nobody        []Answerer
 	)
 	got := logging(t, r, func() (any, error) {
 		changes := Log("changes")
@@ -272,6 +284,16 @@ func TestABundleKeepsALogThroughTheRuntime(t *testing.T) {
 			watched = &e
 		case <-time.After(5 * time.Second):
 		}
+		// Who answers a verb, through the runtime (D-root, D3): one, then nobody on a machine none answers on.
+		if found, err = Discover("node-engine.root-free", ""); err != nil {
+			return nil, err
+		}
+		if nobody, err = Discover("node-engine.root-free", "g14"); err != nil {
+			return nil, err
+		}
+		if _, err := Discover("", ""); err == nil {
+			return nil, fmt.Errorf("a discover naming no verb was asked")
+		}
 		return "done", nil
 	})
 	if out, isError := text(t, got); isError || out != `"done"` {
@@ -342,6 +364,9 @@ func TestABundleKeepsALogThroughTheRuntime(t *testing.T) {
 		p["from"] != "since" || p["since"] != "2026-10-11T18:00:00Z" || watched == nil || watched.Sequence != 6 {
 		t.Fatalf("a watch asked %s %v and heard %+v", method, p, watched)
 	}
+	if len(found) != 1 || found[0] != (Answerer{Machine: "ace", Module: "node-tools"}) || nobody == nil || len(nobody) != 0 {
+		t.Fatalf("discover found %+v, and on g14 %+v", found, nobody)
+	}
 	if info == nil || info.Entries != 6 || info.MaxBytes != 1<<30 || info.First != 1 || info.Last != 6 || info.Bytes == 0 {
 		t.Fatalf("the log's info is %+v", info)
 	}