diff --git a/go/packages_list_test.go b/go/packages_list_test.go
new file mode 100644
index 0000000..8d224e0
--- /dev/null
+++ b/go/packages_list_test.go
@@ -0,0 +1,76 @@
+package stdio
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io/fs"
+	"path/filepath"
+	"slices"
+	"strings"
+	"testing"
+)
+
+// meshSDKPackages is every package mesh-sdk holds (novox/hq ADR 0593 §1): what every module shares, the value shapes
+// and names more than one part reads, and the seat contracts it holds until they move into SDK modules (issue 167).
+// Logic only some modules need is its owner module's package. A package added here is a decision to say in the pull
+// request: does every module share it, or is it a shape more than one part reads?
+var meshSDKPackages = []string{
+	".", "announce", "announcetest", "asker", "asks", "buildstep", "buscompose", "busretry", "calladdress", "catalogue",
+	"composer", "declaration", "delivery", "forgekey", "handacts", "health", "internal/beside", "kvlimit", "membership",
+	"objectlink", "outward", "overlay", "pernode", "process", "provider", "provider/harness", "provisions",
+	"sdkversion", "seal", "testbus",
+}
+
+// computesNot are the functions whose computation is one owner's alone (ADR 0593 §2, §7): the indexer computes a
+// fingerprint, its named tree and a package's version; the node-engine composes.
+var computesNot = []string{"SourceFingerprint", "SourceFingerprint2", "NamedTree", "MeshPackagesOf", "PackageVersionsOf",
+	"OtherPackages", "Compose", "CompositionsShadow", "JudgeMove", "Run"}
+
+// ADR 0593 §1's check: mesh-sdk holds exactly the packages it keeps, and none of them computes what one owner alone
+// computes.
+func TestMeshSDKHoldsOnlyWhatEveryModuleShares(t *testing.T) {
+	var found []string
+	err := filepath.WalkDir(".", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			if n := d.Name(); n == "testdata" || (strings.HasPrefix(n, ".") && path != ".") {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		if !strings.HasSuffix(path, ".go") || strings.HasSuffix(path, "_test.go") {
+			return nil
+		}
+		dir := filepath.ToSlash(filepath.Dir(path))
+		if !slices.Contains(found, dir) {
+			found = append(found, dir)
+		}
+		file, err := parser.ParseFile(token.NewFileSet(), path, nil, parser.SkipObjectResolution)
+		if err != nil {
+			return err
+		}
+		for _, decl := range file.Decls {
+			if fn, ok := decl.(*ast.FuncDecl); ok && fn.Recv == nil && slices.Contains(computesNot, fn.Name.Name) {
+				t.Errorf("%s: %s computes what its owner alone computes (ADR 0593 §2, §7)", path, fn.Name.Name)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	slices.Sort(found)
+	for _, dir := range found {
+		if !slices.Contains(meshSDKPackages, dir) {
+			t.Errorf("mesh-sdk holds the package %s, which it does not keep (ADR 0593 §1): it is its owner module's package", dir)
+		}
+	}
+	for _, want := range meshSDKPackages {
+		if !slices.Contains(found, want) {
+			t.Errorf("mesh-sdk's list keeps %s, which is gone: take it off the list", want)
+		}
+	}
+}