The lab stands in for the builder on an upstream artifact too: the reference the manifest pins

hello-web's server is somebody else's image the mesh would copy in (ADR 0096); the
loader refused it as an artifact nobody stocked.

test/catalogue-module.test.ts

@@ -85,3 +85,17 @@ test("a manifest the catalogue does not have is refused by name", () => {
     assert.throws(() => catalogueModule("nothing", held), /no manifest for nothing/);
   } finally { restore(); }
 });
+
+test("an upstream artifact resolves to the reference the manifest pins, as the machine pulls it", () => {
+  const web = {
+    module: "thing", version: "1",
+    resources: [{ id: "server", type: "container", name: "web", artifact: "server" }],
+    build: { artifacts: [{ name: "server", kind: "upstream", from: "alpine@" + digest("e") }] },
+  };
+  const restore = aCatalogueWith(web);
+  try {
+    const m = JSON.parse(catalogueModule("thing", held)) as { resources: Record<string, unknown>[] };
+    assert.equal(m.resources[0]!["image"], "alpine@" + digest("e"));
+    assert.equal(m.resources[0]!["artifact"], undefined);
+  } finally { restore(); }
+});

test/integration/harness.ts

@@ -306,12 +306,22 @@ export interface ForTheLab {
 export function catalogueModule(module: string, held: HeldImage[], lab: ForTheLab = {}): string {
   const m = JSON.parse(readFileSync(catalogueManifest(module), "utf8")) as {
     resources?: { id: string; type: string; image?: string; artifact?: string; ports?: string[]; env?: Record<string, string> }[];
-    build?: unknown;
+    build?: { artifacts?: { name: string; kind: string; from?: string }[] };
   };
   const artifacts: Record<string, string> = { runtime: `mesh-runtime-${module}`, ...(lab.artifacts ?? {}) };
+  // An upstream artifact is somebody else's image, which the mesh's builder copies into its own
+  // registry (ADR 0096). The lab stands in for the builder by using the reference the manifest
+  // pins, which the machine pulls over its uplink — the same bytes, without the copy.
+  const upstream = new Map<string, string>();
+  for (const a of m.build?.artifacts ?? []) {
+    if (a.kind === "upstream" && a.from) upstream.set(a.name, a.from);
+  }
   for (const r of m.resources ?? []) {
     if (r.type !== "container") continue;
-    if (typeof r.artifact === "string") {
+    if (typeof r.artifact === "string" && upstream.has(r.artifact) && !lab.artifacts?.[r.artifact]) {
+      r.image = onTheMachine(upstream.get(r.artifact)!, held);
+      delete r.artifact;
+    } else if (typeof r.artifact === "string") {
       const repository = artifacts[r.artifact];
       assert.ok(repository,
         `${module}'s container '${r.id}' names the "${r.artifact}" artifact, which the mesh would ` +