The node record states the reader capabilities of the mesh-sdk the engine is built with (ADR 0614 §4, issue 774)

recordOf writes catalogue.ManifestReads in NodeRecord.ManifestReads, once per build, so the assigner moves a want only
to an engine that reads its manifest. A row holds the engine's own manifest to the baseline's words, so its new build is
never held for a word only it reads.

Claude-Session: https://claude.ai/code/session_01JG73KG7AfSdh6FP8VrBqCn

internal/link/have_test.go

@@ -270,7 +270,8 @@ func TestTheNodeKeyCarriesTheNodesFacts(t *testing.T) {
 	}
 	wantRecord := delivery.NodeRecord{V: delivery.Version, Node: "n1", TunnelKey: "tk", SealingKey: "sk", ServingKey: "pk",
 		Certificate: "cert", Trusts: keys.Trusts, Capabilities: []string{"apt", "systemd"}, OutwardLinks: []string{"eth0"}, NetworksSaid: true,
-		Networks: []catalogue.AttachedNetwork{{Link: "eth0", Network: "192.0.2.0/24"}}, Contract: NodeKeyContract}
+		Networks: []catalogue.AttachedNetwork{{Link: "eth0", Network: "192.0.2.0/24"}}, Contract: NodeKeyContract,
+		ManifestReads: catalogue.ManifestReads()} // what it reads of a manifest: its contract's (ADR 0614 §4)
 	if !delivery.SameNodeRecord(*got.Record, wantRecord) {
 		t.Errorf("record = %+v, want %+v", *got.Record, wantRecord)
 	}

internal/link/record.go

@@ -3,6 +3,7 @@ package link
 import (
 	"encoding/json"
 	"sort"
+	"sync"
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
@@ -27,6 +28,11 @@ type RecordKeys struct {
 	Trusts []string
 }
 
+// manifestReads is what this engine reads of a manifest (novox/hq ADR 0614 §4): the reader capabilities of the mesh-sdk it
+// is built with, stated in its record so the assigner moves a want only to an engine that reads its manifest. Computed
+// once: it is the build's, and never changes while it runs.
+var manifestReads = sync.OnceValue(catalogue.ManifestReads)
+
 // recordOf is the node's record from one facts report and its keys; nil for a report that carries no profile (one that
 // says nothing of the machine, such as a rekey), so the record last written stands.
 func recordOf(node string, r Report, keys RecordKeys) *delivery.NodeRecord {
@@ -47,7 +53,8 @@ func recordOf(node string, r Report, keys RecordKeys) *delivery.NodeRecord {
 		return nil
 	}
 	rec := &delivery.NodeRecord{V: delivery.Version, Node: node, TunnelKey: keys.TunnelKey, SealingKey: keys.SealingKey,
-		ServingKey: keys.ServingKey, Certificate: keys.Certificate, Authority: keys.Authority, Trusts: keys.Trusts}
+		ServingKey: keys.ServingKey, Certificate: keys.Certificate, Authority: keys.Authority, Trusts: keys.Trusts,
+		ManifestReads: manifestReads()}
 	for _, c := range p.Capabilities {
 		if c.Present && c.Name != "" {
 			rec.Capabilities = append(rec.Capabilities, c.Name)