diff --git a/go/delivery/builder.go b/go/delivery/builder.go
index 981bca7..447196d 100644
--- a/go/delivery/builder.go
+++ b/go/delivery/builder.go
@@ -184,10 +184,10 @@ type BuilderBuild struct {
 	// does not yet hold: the key is not claimed until that package's trunk key is done and published (novox/hq ADR 0500
 	// clause 6). A reader that does not know the field reads the key as queued.
 	Waits string `json:"waits,omitempty"`
-	// Asks are, on a building key, the ids of the asks the builder put for it (novox/hq ADR 0525 §1; issue 1887 A4b): a
-	// builder that takes the key over at its start waits for those asks' steps and never puts them again. A reader that
-	// does not know the field reads the key as before.
-	Asks []string `json:"asks,omitempty"`
+	// Asks are, on a building key, the asks the builder put for it by build seat language (AskGo, AskNode, AskImage), each
+	// its id (novox/hq ADR 0525 §1; issue 1887 A4b): a builder that takes the key over at its start waits for those asks'
+	// steps and never puts them again. A reader that does not know the field reads the key as before.
+	Asks map[string]string `json:"asks,omitempty"`
 }
 
 func (b BuilderBuild) check() error {
@@ -220,10 +220,13 @@ func (b BuilderBuild) check() error {
 			return fmt.Errorf("delivery: the reference %q of the %s %q %s", a.Reference, a.Kind, a.Name, p)
 		}
 	}
-	for _, id := range b.Asks {
+	for language, id := range b.Asks {
 		if b.State != BuildBuilding {
 			return fmt.Errorf("delivery: a %s build names the ask %s; only a building key does", b.State, id)
 		}
+		if err := checkAskLanguage(language); err != nil {
+			return err
+		}
 		if err := checkAskID(id); err != nil {
 			return err
 		}
diff --git a/go/delivery/stepasks_test.go b/go/delivery/stepasks_test.go
index a8d2d11..1cf1ad6 100644
--- a/go/delivery/stepasks_test.go
+++ b/go/delivery/stepasks_test.go
@@ -127,18 +127,19 @@ func TestAskSubjects(t *testing.T) {
 
 // 1887/A4b: a building key names the asks put for it; a done key or a name that is no ask id is refused.
 func TestABuildingKeyNamesItsAsks(t *testing.T) {
-	b := BuilderBuild{State: BuildBuilding, By: "novox.builder", Asks: []string{"mh3k2x9qa1b2c3"}}
+	b := BuilderBuild{State: BuildBuilding, By: "novox.builder", Asks: map[string]string{AskGo: "mh3k2x9qa1b2c3"}}
 	raw, err := EncodeBuilderBuild(b)
 	if err != nil {
 		t.Fatal(err)
 	}
 	got, err := DecodeBuilderBuild(raw)
-	if err != nil || len(got.Asks) != 1 || got.Asks[0] != "mh3k2x9qa1b2c3" {
+	if err != nil || len(got.Asks) != 1 || got.Asks[AskGo] != "mh3k2x9qa1b2c3" {
 		t.Fatalf("decoded %+v, %v", got, err)
 	}
 	for _, bad := range []BuilderBuild{
-		{State: BuildBuilding, Asks: []string{"postgres"}},
-		{State: BuildFailed, Error: "x", Asks: []string{"mh3k2x9qa1b2c3"}},
+		{State: BuildBuilding, Asks: map[string]string{AskGo: "postgres"}},
+		{State: BuildBuilding, Asks: map[string]string{"typescript": "mh3k2x9qa1b2c3"}},
+		{State: BuildFailed, Error: "x", Asks: map[string]string{AskGo: "mh3k2x9qa1b2c3"}},
 	} {
 		if _, err := EncodeBuilderBuild(bad); err == nil {
 			t.Errorf("encoded %+v", bad)