diff --git a/modules/mesh-build-go/buildstep/generated_test.go b/modules/mesh-build-go/buildstep/generated_test.go
index eb4830260..6cbce0b76 100644
--- a/modules/mesh-build-go/buildstep/generated_test.go
+++ b/modules/mesh-build-go/buildstep/generated_test.go
@@ -21,9 +21,9 @@ func contracts(t *testing.T, manifest string) (string, []string) {
 	dir := t.TempDir()
 	for p, text := range map[string]string{
 		"module.json":               manifest,
-		"seats/one-store/seat.json": `{"format":1,"seat":"one-store","scope":"mesh","grain":"whole","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"},"answer":{"type":"object"}}]}`,
+		"seats/one-store/seat.json": `{"format":1,"seat":"one-store","scope":"mesh","grain":"whole","domain":"Module","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"},"answer":{"type":"object"}}]}`,
 		// A definition at the seat-list grain is read and generates nothing (ADR 0635 §1, §2).
-		"seats/other/seat.json": `{"format":1,"seat":"other","scope":"mesh","grain":"seat-list","decision":"ADR 1","verbs":[{"name":"ask","input":{"type":"object"}}]}`,
+		"seats/other/seat.json": `{"format":1,"seat":"other","scope":"mesh","grain":"seat-list","domain":"Module","decision":"ADR 1","verbs":[{"name":"ask","input":{"type":"object"}}]}`,
 	} {
 		writeContract(t, filepath.Join(dir, p), text)
 	}
diff --git a/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/a-registry/seat.json b/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/a-registry/seat.json
index 77642d3c9..3fe5feecc 100644
--- a/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/a-registry/seat.json
+++ b/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/a-registry/seat.json
@@ -1,4 +1,4 @@
-{"format":1,"seat":"a-registry","scope":"mesh","grain":"whole","decision":"ADR 1","includes":["registry"],
+{"format":1,"seat":"a-registry","scope":"mesh","grain":"whole","domain":"Module","decision":"ADR 1","includes":["registry"],
  "verbs":[{"name":"hold","input":{"type":"object"},"answer":{"type":"object"}}],
  "family":{"name":"a-registry.events","max-age-days":7},
  "states":[
diff --git a/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/b-registry/seat.json b/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/b-registry/seat.json
index cff301db1..984e450ac 100644
--- a/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/b-registry/seat.json
+++ b/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/b-registry/seat.json
@@ -1,3 +1,3 @@
-{"format":1,"seat":"b-registry","scope":"mesh","grain":"whole","decision":"ADR 1","includes":["registry"],
+{"format":1,"seat":"b-registry","scope":"mesh","grain":"whole","domain":"Module","decision":"ADR 1","includes":["registry"],
  "verbs":[{"name":"hold","input":{"type":"object"},"answer":{"type":"object"}}],
  "family":{"name":"b-registry.events","max-age-days":7}}
diff --git a/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/one-store/seat.json b/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/one-store/seat.json
index 3e0501a66..f742e27fa 100644
--- a/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/one-store/seat.json
+++ b/modules/mesh-build-go/buildstep/seatgen/testdata/contracts/seats/one-store/seat.json
@@ -1 +1 @@
-{"format":1,"seat":"one-store","scope":"mesh","grain":"seat-list","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"}}]}
+{"format":1,"seat":"one-store","scope":"mesh","grain":"seat-list","domain":"Module","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"}}]}
diff --git a/modules/mesh-build-go/cmd/mesh-build-go/test_test.go b/modules/mesh-build-go/cmd/mesh-build-go/test_test.go
index 95fe52fd6..f9047dd67 100644
--- a/modules/mesh-build-go/cmd/mesh-build-go/test_test.go
+++ b/modules/mesh-build-go/cmd/mesh-build-go/test_test.go
@@ -186,7 +186,7 @@ func TestUnitLevelOfAContractsModuleOutOfStepFailsNamingEachPath(t *testing.T) {
 	tree := filepath.Join(m.Work, ws, "tree")
 	for p, text := range map[string]string{
 		"module.json":               `{"module":"c","build":{"artifacts":[{"name":"go","kind":"package","language":"go","paths":["go"],"generated-from":"."}]}}`,
-		"seats/one-store/seat.json": `{"format":1,"seat":"one-store","scope":"mesh","grain":"seat-list","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"}}]}`,
+		"seats/one-store/seat.json": `{"format":1,"seat":"one-store","scope":"mesh","grain":"seat-list","domain":"Module","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"}}]}`,
 		"go/go.mod":                 "module example.org/c/go\n",
 		"go/stray.go":               "package stray\n",
 		"ts/package.json":           `{"name":"@example/c"}`,
@@ -220,7 +220,7 @@ func TestUnitLevelOfAContractsModuleInAFolderOutOfStepFailsNamingEachPath(t *tes
 	tree := filepath.Join(m.Work, ws, "tree")
 	for p, text := range map[string]string{
 		"module.json":               `{"module":"c","build":{"artifacts":[{"name":"go","kind":"package","language":"go","paths":["go"],"generated-from":"."}]}}`,
-		"seats/one-store/seat.json": `{"format":1,"seat":"one-store","scope":"mesh","grain":"seat-list","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"}}]}`,
+		"seats/one-store/seat.json": `{"format":1,"seat":"one-store","scope":"mesh","grain":"seat-list","domain":"Module","decision":"ADR 1","verbs":[{"name":"query","input":{"type":"object"}}]}`,
 		"go/go.mod":                 "module example.org/c/go\n",
 		"go/stray.go":               "package stray\n",
 		"ts/package.json":           `{"name":"@example/c"}`,