A tool container on the runtime's image is refused once the runtime is registered (hq ADR 0175, to-be 38 WP2.4)

A module declaring tools, a container, and a build on mesh-tools' runtime image is a container whose
purpose is serving tools — the pattern the node's tool runtime retires. Once node-tools is in the
catalogue, registering one is refused by name, with the record that says why; before, it is accepted
as it always was, so a mesh converts in the design's order and nothing is refused before there is
anything to move to. This is the mechanism that keeps the old pattern from returning by habit.

Judged from a repository manifest's own build.on, and for a built manifest — which carries no build
— from what its build stood on, now recorded beside the commit as part of a module's provenance.

internal/inventory/catalogue.go

@@ -42,6 +42,11 @@ type Source struct {
 	// Seen is when the source was last looked at — by a build, by hand, or by the forge saying it
 	// moved. What a late report of an older move is judged against.
 	Seen time.Time
+	// Against is every artifact the build this manifest came from stood on, as recorded. Part of a
+	// module's provenance like the commit is, and what tells a built manifest's base when the manifest
+	// itself no longer carries its build (novox/hq to-be 38 WP2.4). Empty for a manifest handed over
+	// by hand, which carries its `build.on` itself.
+	Against []string
 }
 
 // Current reports whether what the mesh holds is what the source last had.
@@ -61,6 +66,22 @@ func (s Source) Current() bool {
 // gains a requirement, a claim, a resource. What matters is that the change is visible the next
 // time a node is resolved, which it is.
 func (i *Inventory) RegisterModule(ctx context.Context, m catalogue.Manifest, from Source) error {
+	// **Once the node's tool runtime is in the catalogue, the pattern it retires is refused**
+	// (novox/hq ADR 0175, to-be 38 WP2.4): a module serving its tools from a container built on the
+	// runtime's image. Refused at registration, by name, because this is the mechanism that keeps
+	// the old pattern from returning by habit — a rebuild of an unmoved module stops here with the
+	// record that says why. Before the runtime exists the pattern is accepted as it always was.
+	if m.Module != catalogue.RuntimeModule {
+		if why := catalogue.ToolContainerOnTheRuntime(m, from.Against); why != "" {
+			runtime, err := i.hasModule(ctx, catalogue.RuntimeModule)
+			if err != nil {
+				return err
+			}
+			if runtime {
+				return fmt.Errorf("%s is not registered: %s", m.Module, why)
+			}
+		}
+	}
 	raw, err := json.Marshal(m)
 	if err != nil {
 		return err
@@ -89,6 +110,16 @@ func (i *Inventory) RegisterModule(ctx context.Context, m catalogue.Manifest, fr
 	return err
 }
 
+// hasModule is whether the catalogue holds a module of that name.
+func (i *Inventory) hasModule(ctx context.Context, name string) (bool, error) {
+	var one int
+	err := i.store.Pool().QueryRow(ctx, `select 1 from module where name = $1`, name).Scan(&one)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return false, nil
+	}
+	return err == nil, err
+}
+
 // SourceMoved records that a module's source has a newer commit than the mesh has built.
 //
 // This is the whole of noticing. Nothing here builds anything — it writes down that the two