Read seat verbs' replaces from mesh-sdk's seat contract and seat holders from placement's seat-holders state, so the console asks the controller for neither (issue 1955, ADR 0571 clauses 4 and 5)

Pins mesh-sdk f9a496d. The controller's nodes and modules reads remain.

node-tools/internal/console/address.go

@@ -17,6 +17,9 @@ package console
 // session — so a tool that arrived a minute ago is found without the client reconnecting.
 
 import (
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
 	"context"
 	"encoding/json"
 	"fmt"
@@ -134,7 +137,11 @@ type index struct {
 	// what it serves in time, or it answered before and not now. An address it might answer is never
 	// called missing while it is here (2026-10-05).
 	Unheard []unheard
-	// Replaces is what each verb and tool replaces, from the controller's records (novox/hq ADR 0245):
+	// Placed is the state seat-holders as the seat mesh-placement's holder wrote it (novox/hq ADR 0571 clause 4), by its
+	// keys `<seat>` and `<seat>.<node>`, read with delivery.HoldersOf; PlacedWhy says why it could not be read.
+	Placed    map[string][]byte
+	PlacedWhy string
+	// Replaces is what each verb and tool replaces (novox/hq ADR 0245):
 	// `seat:<seat>.<verb>` and `<module>.<tool>`.
 	Replaces map[string][]string
 	// Earlier is every runtime not heard this round whose last answer, within RuntimeForgotten, this
@@ -283,18 +290,13 @@ type recordedMachine struct {
 func indexOn(conn *bus.Conn, held announce.Known, before func(announce.Discovery) []earlier) (*index, error) {
 	var wg sync.WaitGroup
 	var nodesOut, modulesOut string
-	var toolsAnswer json.RawMessage
+	var placed map[string][]byte
+	var placedErr error
 	wg.Add(3)
 	go func() { defer wg.Done(); nodesOut, _ = controllerOutput(conn, "nodes") }()
 	go func() { defer wg.Done(); modulesOut, _ = controllerOutput(conn, "modules") }()
-	// The seats' verbs as the records define them, for what each replaces (novox/hq ADR 0245): answered
-	// in-process from the records, never a command.
-	go func() {
-		defer wg.Done()
-		if got, err := conn.Ask("seat:mesh-controller.tools", map[string]any{}, ""); err == nil {
-			toolsAnswer = got.Result
-		}
-	}()
+	// Who holds which seat on which node, from placement (ADR 0571 clause 4): no call of the controller.
+	go func() { defer wg.Done(); placed, placedErr = seatHoldersOn(conn) }()
 	d, err := announce.Gather(conn, held)
 	wg.Wait()
 	if err != nil {
@@ -333,6 +335,10 @@ func indexOn(conn *bus.Conn, held announce.Known, before func(announce.Discovery
 	l := x.Listing
 	x.Discovery = d
 	x.Stale, x.Earlier = stale, earlierAt
+	x.Placed = placed
+	if placedErr != nil {
+		x.PlacedWhy = placedErr.Error()
+	}
 	for _, s := range d.Silent {
 		x.Unheard = append(x.Unheard, unheard{Runtime: s.Name, Machine: s.Machine,
 			Why: fmt.Sprintf("it answered PING; what it serves did not arrive within %s", announce.Patience)})
@@ -342,7 +348,7 @@ func indexOn(conn *bus.Conn, held announce.Known, before func(announce.Discovery
 	// a module with no tools is never a name here.
 	var recorded []recordedModule
 	recordedOK := json.Unmarshal([]byte(jsonIn(modulesOut)), &recorded) == nil
-	x.Replaces = replacesOf(toolsAnswer, recorded)
+	x.Replaces = replacesOf(catalogue.DefaultSeats(), recorded)
 	if recordedOK {
 		for _, m := range recorded {
 			if !m.Tools {
@@ -360,6 +366,10 @@ func indexOn(conn *bus.Conn, held announce.Known, before func(announce.Discovery
 	} else {
 		l.NotAnswering = append(l.NotAnswering, "mesh-controller (its records of the modules did not answer, so what is missing cannot be said)")
 	}
+	if x.PlacedWhy != "" {
+		l.NotAnswering = append(l.NotAnswering, delivery.SeatHoldersRead+" (who holds which seat by placement could not be read: "+
+			x.PlacedWhy+")")
+	}
 	for _, u := range x.Unheard {
 		l.NotAnswering = append(l.NotAnswering, "the runtime "+sayUnheard([]unheard{u}))
 	}
@@ -381,6 +391,50 @@ func indexOn(conn *bus.Conn, held announce.Known, before func(announce.Discovery
 	return x, nil
 }
 
+// seatHoldersOn reads the state seat-holders whole (novox/hq ADR 0571 clause 4): its current values, through the
+// runtime's own membership, which reads it as delivery.SeatHoldersRead.
+func seatHoldersOn(conn *bus.Conn) (map[string][]byte, error) {
+	var mu sync.Mutex
+	keys := map[string][]byte{}
+	stop, err := conn.StateWatch(conn.Credential().Module, delivery.SeatHoldersRead, "", func(c bus.StateChange) error {
+		if c.Current && c.Op == "put" {
+			mu.Lock()
+			keys[c.Key] = c.Value
+			mu.Unlock()
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	stop()
+	mu.Lock()
+	defer mu.Unlock()
+	return keys, nil
+}
+
+// placedHolders is who holds seat (on node, for a seat held per machine) by placement, or none.
+func (x *index) placedHolders(seat, node string) []delivery.SeatHolder {
+	if len(x.Placed) == 0 {
+		return nil
+	}
+	hs, err := delivery.HoldersOf(x.Placed, seat, node)
+	if err != nil || len(hs) > 0 || node != "" {
+		return hs
+	}
+	// A seat held per machine, asked without one: every node's key of it.
+	var all []delivery.SeatHolder
+	for key := range x.Placed {
+		if s, n, ok := strings.Cut(key, "."); ok && s == seat {
+			if more, err := delivery.HoldersOf(x.Placed, seat, n); err == nil {
+				all = append(all, more...)
+			}
+		}
+	}
+	sort.Slice(all, func(i, j int) bool { return all[i].Node+"/"+all[i].Module < all[j].Node+"/"+all[j].Module })
+	return all
+}
+
 func containsHolder(hs []holder, h holder) bool {
 	for _, x := range hs {
 		if x == h {
@@ -606,6 +660,14 @@ func resolve(x *index, address string) (target, error) {
 			return target{}, fmt.Errorf("%s is assigned to %s in the mesh's records, but nothing that answered discovery serves it: %s. "+
 				"Ask again in a moment; mesh_runtimes shows which runtimes answered", prefix, strings.Join(on, ", "), why)
 		}
+		if hs := x.placedHolders(prefix, node); len(hs) > 0 {
+			var held []string
+			for _, h := range hs {
+				held = append(held, h.Module+" on "+h.Node)
+			}
+			return target{}, fmt.Errorf("the seat %s is held by %s by placement, but no holder of it announced itself on the bus. "+
+				"Ask again in a moment; mesh_runtimes shows which runtimes answered", prefix, strings.Join(held, ", "))
+		}
 		if len(x.Unheard) > 0 {
 			return target{}, fmt.Errorf("nothing that answered discovery is called %s, but not every runtime answered: %s — "+
 				"%s may be theirs. Ask again in a moment; mesh_runtimes shows which runtimes answered", prefix, sayUnheard(x.Unheard), prefix)