diff --git a/src/utils/deploy.ts b/src/utils/deploy.ts
index 5c5d8134..76d3792c 100644
--- a/src/utils/deploy.ts
+++ b/src/utils/deploy.ts
@@ -24,6 +24,7 @@ import {
   ComponentStatus,
   DeployResult,
   DestructiveChangesType,
+  expandD360ComponentSet,
   FileResponseSuccess,
   MetadataApiDeploy,
   MetadataApiDeployOptions,
@@ -119,6 +120,22 @@ export async function buildComponentSet(opts: Partial<DeployOptions>, stl?: Sour
   });
 }
 
+/** True when the deploy includes at least one Data Cloud dataspace-scoped component. */
+const hasD360Components = (requested: ComponentSet): boolean =>
+  [...requested.getSourceComponents()].some((c) => c.type.strategies?.adapter === 'd360');
+
+/**
+ * A dataspace-scoped component's sidecar lists the peers it has to be deployed alongside, under
+ * `retrieveWith`. So when someone deploys one of these, we also pull in those peers (and their peers,
+ * and so on) — but nothing else from the project. To find them we resolve the whole project once,
+ * then hand back the requested set plus that closure.
+ */
+async function expandD360Closure(requested: ComponentSet, registry?: RegistryAccess): Promise<ComponentSet> {
+  // Resolve the whole project so we can look up the retrieveWith peers by their sidecar componentName.
+  const full = await ComponentSetBuilder.build({ sourcepath: await getPackageDirs() });
+  return expandD360ComponentSet(full, requested, registry);
+}
+
 export async function executeDeploy(
   opts: Partial<DeployOptions>,
   project?: SfProject,
@@ -166,6 +183,11 @@ export async function executeDeploy(
     registry = stl.registry;
 
     componentSet = await buildComponentSet(opts, stl);
+    // Dataspace-scoped components need their retrieveWith peers in the same deploy, so pull those in.
+    // Every other deploy leaves the component set untouched.
+    if (hasD360Components(componentSet)) {
+      componentSet = await expandD360Closure(componentSet, registry);
+    }
     if (componentSet.size === 0) {
       if (opts['source-dir'] ?? opts.manifest ?? opts.metadata ?? throwOnEmpty) {
         // the user specified something to deploy, but there isn't anything