diff --git a/contracts/go/clients/meshwantsclient/wants_test.go b/contracts/go/clients/meshwantsclient/wants_test.go
index 490fa692..a621583d 100644
--- a/contracts/go/clients/meshwantsclient/wants_test.go
+++ b/contracts/go/clients/meshwantsclient/wants_test.go
@@ -42,6 +42,7 @@ func TestWantsAreWhatTheEarlierCodecWrote(t *testing.T) {
 			"put":       {Want{Fp: a, Self: true, Put: true, Hold: true, Yes: d, Release: "r1"}, `{"v":1,"fp":"` + a + `","put":true,"hold":true,"yes":"` + d + `","release":"r1","self":true}`},
 			"removed":   {Want{Removed: true, Words: "gone"}, `{"v":1,"removed":true,"words":"gone"}`},
 			"released":  {Want{Fp: a, Composed: c, Version: "0.1.15", Parts: map[string]string{"mesh-sdk:go": d}}, `{"v":1,"fp":"` + a + `","composed":"` + c + `","version":"0.1.15","parts":{"mesh-sdk:go":"` + d + `"}}`},
+			"kept":      {Want{Fp: a, Composed: c, Parts: map[string]string{"x:image": d}, KeptOn: "n1"}, `{"v":1,"fp":"` + a + `","composed":"` + c + `","parts":{"x:image":"` + d + `"},"kept-on":"n1"}`},
 		} {
 			t.Run(name, func(t *testing.T) {
 				raw, err := EncodeWant(row.w)
diff --git a/contracts/go/seats/meshwants/contract.go b/contracts/go/seats/meshwants/contract.go
index 7e958b08..1030ce77 100644
--- a/contracts/go/seats/meshwants/contract.go
+++ b/contracts/go/seats/meshwants/contract.go
@@ -895,7 +895,9 @@ type WantsByWantNodeModuleValue struct {
 	Composed string `json:"composed,omitempty"`
 	Fp       string `json:"fp,omitempty"`
 	Hold     bool   `json:"hold,omitempty"`
-	Newest   string `json:"newest,omitempty"`
+	// for a kept build, the build node that keeps it, from the builder's build.ended; the node-engine fetches the build through that node's seat verb kept-artifact, and a want with none from the store (design 47 G section 526)
+	KeptOn string `json:"kept-on,omitempty"`
+	Newest string `json:"newest,omitempty"`
 	// the digest of each of the module's parts, by artifact reference; the node-engine fetches and checks each part by it (design 47 G section 379)
 	Parts   map[string]string `json:"parts,omitempty"`
 	Put     bool              `json:"put,omitempty"`
diff --git a/contracts/go/seats/meshwants/contract_test.go b/contracts/go/seats/meshwants/contract_test.go
index b21c64c9..32f26b23 100644
--- a/contracts/go/seats/meshwants/contract_test.go
+++ b/contracts/go/seats/meshwants/contract_test.go
@@ -65,6 +65,12 @@ func TestFixtures(t *testing.T) {
 				err := json.Unmarshal(b, &v)
 				return v, err
 			}, subjectIs: nil},
+		{name: "a want for a kept build, naming the node that keeps it", subject: "", given: "{\"fp\":\"ab12\",\"kept-on\":\"n1\",\"parts\":{\"x:image\":\"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef\"},\"v\":1,\"version\":\"0.1.15\"}", wire: "{\"fp\":\"ab12\",\"kept-on\":\"n1\",\"parts\":{\"x:image\":\"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef\"},\"v\":1,\"version\":\"0.1.15\"}",
+			decode: func(b []byte) (any, error) {
+				var v WantsByWantNodeModuleValue
+				err := json.Unmarshal(b, &v)
+				return v, err
+			}, subjectIs: nil},
 		{name: "a node's own want", subject: "", given: "{\"composed\":\"sha256:aa\",\"self\":true,\"v\":1}", wire: "{\"composed\":\"sha256:aa\",\"self\":true,\"v\":1}",
 			decode: func(b []byte) (any, error) {
 				var v WantsByWantNodeNodeValue
diff --git a/contracts/seats/mesh-wants/fixtures/states.json b/contracts/seats/mesh-wants/fixtures/states.json
index 818850d5..85e5d74c 100644
--- a/contracts/seats/mesh-wants/fixtures/states.json
+++ b/contracts/seats/mesh-wants/fixtures/states.json
@@ -8,6 +8,19 @@
       "rule": 3
     }
   },
+  {
+    "name": "a want for a kept build, naming the node that keeps it",
+    "of": "state:wants/want.<node>.<module>",
+    "given": {
+      "v": 1,
+      "fp": "ab12",
+      "version": "0.1.15",
+      "parts": {
+        "x:image": "sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      },
+      "kept-on": "n1"
+    }
+  },
   {
     "name": "a node's own want",
     "of": "state:wants/want.<node>.node",
diff --git a/contracts/seats/mesh-wants/seat.json b/contracts/seats/mesh-wants/seat.json
index ca64e17c..445971f7 100644
--- a/contracts/seats/mesh-wants/seat.json
+++ b/contracts/seats/mesh-wants/seat.json
@@ -542,6 +542,10 @@
                   "type": "string"
                 },
                 "description": "the digest of each of the module's parts, by artifact reference; the node-engine fetches and checks each part by it (design 47 G section 379)"
+              },
+              "kept-on": {
+                "type": "string",
+                "description": "for a kept build, the build node that keeps it, from the builder's build.ended; the node-engine fetches the build through that node's seat verb kept-artifact, and a want with none from the store (design 47 G section 526)"
               }
             }
           },
diff --git a/contracts/ts/seats/meshwants/index.d.ts b/contracts/ts/seats/meshwants/index.d.ts
index 134842cd..81fbc682 100644
--- a/contracts/ts/seats/meshwants/index.d.ts
+++ b/contracts/ts/seats/meshwants/index.d.ts
@@ -513,6 +513,8 @@ export interface WantsByWantNodeModuleValue {
   "composed"?: string;
   "fp"?: string;
   "hold"?: boolean;
+  /** for a kept build, the build node that keeps it, from the builder's build.ended; the node-engine fetches the build through that node's seat verb kept-artifact, and a want with none from the store (design 47 G section 526) */
+  "kept-on"?: string;
   "newest"?: string;
   /** the digest of each of the module's parts, by artifact reference; the node-engine fetches and checks each part by it (design 47 G section 379) */
   "parts"?: Record<string, string>;