diff --git a/go/delivery/forge_inputs_test.go b/go/delivery/forge_inputs_test.go
index 5e4b78b..7b1893a 100644
--- a/go/delivery/forge_inputs_test.go
+++ b/go/delivery/forge_inputs_test.go
@@ -69,6 +69,11 @@ func TestForgeMergedRefusesBadInputs(t *testing.T) {
 		// ADR 0565 §2 (issue 1953 D1): the predefined list is one JSON object, said present or absent, never both.
 		"predefined not an object": {func(f *Forge) { f.Predefined = []byte(`["domain"]`) }, "one JSON object"},
 		"predefined both":          {func(f *Forge) { f.Predefined = []byte(`{}`); f.PredefinedRead = true }, "says the merge holds none"},
+		// A deleted branch names its branch and carries nothing else (design 51 *Tagged versions*).
+		"branch-deleted with no branch": {func(f *Forge) { *f = Forge{Kind: ForgeBranchDeleted, Repository: "novox/mesh-sdk"} }, "needs the branch"},
+		"branch-deleted with a head": {func(f *Forge) {
+			*f = Forge{Kind: ForgeBranchDeleted, Repository: "novox/mesh-sdk", Branch: "feat/x", Head: "aaaa"}
+		}, "carries nothing else"},
 	} {
 		f := mergedWithInputs()
 		tc.mut(&f)
diff --git a/go/delivery/source.go b/go/delivery/source.go
index 3956884..6eebdfb 100644
--- a/go/delivery/source.go
+++ b/go/delivery/source.go
@@ -47,6 +47,10 @@ const (
 	ForgeMerged  = "merged"
 	ForgeRefused = "refused"
 	ForgeOpen    = "open"
+	// ForgeBranchDeleted says a branch of a repository was deleted on the forge, from the forge's own delete event
+	// (design 51 *Tagged versions*): the builder removes the tagged versions it asked for that branch. It names the
+	// repository and the branch and carries nothing else. A reader that does not know the kind ignores it.
+	ForgeBranchDeleted = "branch-deleted"
 )
 
 // OpenPull names an open pull request into the trunk: the repository as `<owner>/<name>` and the number.
@@ -166,10 +170,10 @@ func checkRepository(repository string) error {
 
 func checkForgeKind(kind string) error {
 	switch kind {
-	case ForgePull, ForgeMerged, ForgeRefused, ForgeOpen:
+	case ForgePull, ForgeMerged, ForgeRefused, ForgeOpen, ForgeBranchDeleted:
 		return nil
 	}
-	return fmt.Errorf("delivery: the forge kind %q is not pull, merged, refused or open", kind)
+	return fmt.Errorf("delivery: the forge kind %q is not pull, merged, refused, open or branch-deleted", kind)
 }
 
 // ForgeEvent is the name of a forge message of the given kind: `forge.<owner>.<name>.<kind>`.
@@ -704,6 +708,14 @@ func (f Forge) check() error {
 		if err := f.checkInputs(func(d string) bool { _, ok := f.Trees[d]; return ok }, "its trees"); err != nil {
 			return err
 		}
+	case ForgeBranchDeleted:
+		if f.Branch == "" {
+			return fmt.Errorf("delivery: a branch-deleted message needs the branch")
+		}
+		if f.Number != 0 || f.Head != "" || f.Merge != "" || len(f.Dirs) > 0 || len(f.Trees) > 0 || len(f.Manifests) > 0 ||
+			len(f.Locks) > 0 || len(f.Paths) > 0 || len(f.Packages) > 0 || f.Act != "" {
+			return fmt.Errorf("delivery: a branch-deleted message names its repository and branch and carries nothing else")
+		}
 	case ForgeRefused:
 		if len(f.Dirs) > 0 || f.DirsKnown {
 			return fmt.Errorf("delivery: a refused message carries no module directories")
diff --git a/go/delivery/source_test.go b/go/delivery/source_test.go
index 838d395..48b096b 100644
--- a/go/delivery/source_test.go
+++ b/go/delivery/source_test.go
@@ -44,7 +44,7 @@ func TestSourceKeys(t *testing.T) { // 1200/AC1
 	if err != nil || repo != "novox/mesh-sdk" || kind != ForgeMerged {
 		t.Fatalf("parse forge event = %q %q %v", repo, kind, err)
 	}
-	for _, k := range []string{ForgePull, ForgeMerged, ForgeRefused} {
+	for _, k := range []string{ForgePull, ForgeMerged, ForgeRefused, ForgeBranchDeleted} {
 		if _, err := ForgeEvent("a/b", k); err != nil {
 			t.Errorf("kind %s refused: %v", k, err)
 		}
@@ -150,6 +150,8 @@ func sampleForges() []Forge {
 			Trees: map[string]string{"modules/a": "t1"}, Root: "t0"},
 		{Kind: ForgeRefused, Repository: "novox/mesh-sdk", Act: "novox/mesh-sdk.36.aaaa.view", Words: "403 forbidden"},
 		{Kind: ForgeOpen, Open: []OpenPull{{Repository: "novox/mesh-sdk", Number: 36}, {Repository: "novox/mesh-control", Number: 7}}},
+		// A deleted branch, from the forge's delete event (design 51 *Tagged versions*).
+		{Kind: ForgeBranchDeleted, Repository: "novox/mesh-sdk", Branch: "feat/x"},
 	}
 }