diff --git a/go/delivery/stepasks.go b/go/delivery/stepasks.go
index 85da720..110cd21 100644
--- a/go/delivery/stepasks.go
+++ b/go/delivery/stepasks.go
@@ -266,17 +266,19 @@ type StepAsk struct {
 }
 
 // PackageVersions are the versions of the mesh packages a build or a check builds against, by package (a Go module's
-// path), each a full commit (novox/hq ADR 0573 §2).
+// path): each a full commit (novox/hq ADR 0573 §2), or a Go semantic version, the form a delivery group's check names the
+// group's tagged version in (`v0.1.15-feat-x.2`, ADR 0607 §3, §5; design 51 *Tagged versions*).
 type PackageVersions map[string]string
 
-// Check refuses a package that is no module path or a version that is no full commit, naming it.
+// Check refuses a package that is no module path or a version that is neither a full commit nor a Go semantic version,
+// naming it.
 func (p PackageVersions) Check() error {
 	for pkg, version := range p {
 		if pkg == "" || strings.ContainsAny(pkg, " \t\n@") || strings.HasPrefix(pkg, "/") {
 			return fmt.Errorf("delivery: the package %q is no module path", pkg)
 		}
-		if !askCommitOK.MatchString(version) {
-			return fmt.Errorf("delivery: the package %s names the version %q, which is no full commit", pkg, version)
+		if !askCommitOK.MatchString(version) && !PackageSemver.MatchString(version) {
+			return fmt.Errorf("delivery: the package %s names the version %q, which is neither a full commit nor a Go semantic version (v0.1.15-feat-x.2)", pkg, version)
 		}
 	}
 	return nil
@@ -527,6 +529,10 @@ func (c CheckJob) check(id string) error {
 
 var askCommitOK = regexp.MustCompile(`^[0-9a-f]{40}$`)
 
+// PackageSemver is a Go semantic version a package may be named at (PackageVersions): v, three numbers, and an optional
+// pre-release of Semantic Versioning's characters (a tagged version's, ADR 0607 §1).
+var PackageSemver = regexp.MustCompile(`^v(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$`)
+
 // checkFetchArgs refuses fetch arguments with no repository or no full commit; the rest is the build module's fetch to
 // judge, as a direct call's is.
 func checkFetchArgs(id string, args map[string]any) error {
diff --git a/go/delivery/stepasks_test.go b/go/delivery/stepasks_test.go
index 0dcc50f..bcdcc41 100644
--- a/go/delivery/stepasks_test.go
+++ b/go/delivery/stepasks_test.go
@@ -28,7 +28,8 @@ func checkAsk() StepAsk {
 		Check: &CheckJob{Fetch: map[string]any{"repository": "novox/mesh-catalog", "commit": askCommit, "ref": "refs/pull/3/head", "base": askCommit},
 			Levels: []string{LevelUnit, LevelIntegration}, Kept: true, Runner: "workspace", RunnerWhen: "modules/mesh-build-go/", Run: "",
 			NodeNames: []string{"anchor", "laptop"}},
-		Packages: PackageVersions{"git.novox.be/novox/mesh-sdk/go": askCommit, "git.novox.be/novox/mesh-controller/modules/route-proxy/contract": askCommit}}
+		Packages: PackageVersions{"git.novox.be/novox/mesh-sdk/go": askCommit, "git.novox.be/novox/mesh-controller/modules/route-proxy/contract": askCommit,
+			"git.novox.be/novox/mesh-contracts/go": "v0.1.15-feat-x.2"}} // ADR 0607 §5: a group's tagged version
 }
 
 // 1887/A1a: an ask encodes and decodes with every field; 1585/S4: the package versions too.
@@ -61,9 +62,11 @@ func TestAskRefusesUnknownKindAndLanguage(t *testing.T) {
 		"commit":   func(a *StepAsk) { a.Build.Fetch = map[string]any{"repository": "novox/x", "commit": "main"} },
 		"path":     func(a *StepAsk) { a.Build.Path = "" },
 		"needs":    func(a *StepAsk) { a.Needs = []string{NeedNodeBuildNode} }, // issue 890: a build needs no node
-		// Issue 1585: a package's version is a full commit, of a module path.
-		"version": func(a *StepAsk) { a.Packages["git.novox.be/novox/mesh-sdk/go"] = "v0.1.7" },
-		"package": func(a *StepAsk) { a.Packages["git.novox.be/novox/x y"] = askCommit },
+		// Issue 1585, ADR 0607 §5: a package's version is a full commit or a Go semantic version, of a module path.
+		"version":   func(a *StepAsk) { a.Packages["git.novox.be/novox/mesh-sdk/go"] = "main" },
+		"no v":      func(a *StepAsk) { a.Packages["git.novox.be/novox/mesh-sdk/go"] = "0.1.15-feat-x.2" },
+		"pre-chars": func(a *StepAsk) { a.Packages["git.novox.be/novox/mesh-sdk/go"] = "v0.1.15-feat/x.2" },
+		"package":   func(a *StepAsk) { a.Packages["git.novox.be/novox/x y"] = askCommit },
 		"compose": func(a *StepAsk) {
 			a.Kind, a.Build = AskCheck, nil
 			a.Compose = &ComposeJob{Fetch: map[string]any{"repository": "novox/mesh-sdk", "commit": askCommit}, Dir: "go", Package: "x", Request: json.RawMessage(`{}`)}