fix(nodebuilder/tests): fix API and pruning integration test flakes

TestHeaderSubscription: explicitly connect bridge and light nodes via
mocknet.ConnectPeers, wait for initial sync, and add a delay for
gossipsub heartbeat exchange before subscribing. The bridge uses
FanoutOnly mode which requires subscription metadata propagation.

TestArchivalBlobSync: use assert.Eventually instead of assert.False
for EDS pruning checks. Pruning FNs fetch blocks from core during
catch-up and the pruner needs time to remove data outside the
availability window.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rootulp

nodebuilder/tests/api_test.go

@@ -151,20 +151,23 @@ func TestHeaderSubscription(t *testing.T) {
 	require.NoError(t, err)
 	sw.SetBootstrapper(t, bridge)
 
-	bridgeClient := getAdminClient(ctx, bridge, t)
-
-	// Wait for the bridge to accumulate blocks so the light node's initial
-	// header exchange sync generates subscription events without relying on
-	// gossipsub (which is unreliable in mocknet with FanoutOnly bridge nodes).
-	_, err = bridgeClient.Header.WaitForHeight(ctx, 10)
-	require.NoError(t, err)
-
 	// start a light node that's connected to the bridge node
 	light := sw.NewLightNode()
 	err = light.Start(ctx)
 	require.NoError(t, err)
 
+	// Explicitly connect bridge and light, then wait for gossipsub mesh
+	// formation. Bridge nodes use FanoutOnly for header gossipsub, so we
+	// need to ensure the connection is established and gossipsub has
+	// exchanged subscription metadata before subscribing.
+	sw.Connect(t, bridge, light)
+
 	lightClient := getAdminClient(ctx, light, t)
+	// Wait for the light to sync a few headers (proves connectivity) and
+	// give gossipsub heartbeats time to propagate subscription info.
+	_, err = lightClient.Header.WaitForHeight(ctx, 3)
+	require.NoError(t, err)
+	time.Sleep(3 * time.Second)
 
 	// subscribe to headers via the light node's RPC header subscription
 	subctx, subcancel := context.WithCancel(ctx)

nodebuilder/tests/prune_test.go

@@ -152,12 +152,16 @@ func TestArchivalBlobSync(t *testing.T) {
 	}
 
 	// ensure pruned FNs don't have the blocks associated
-	// with the historical blobs
+	// with the historical blobs. Use Eventually because the pruning FNs may
+	// fetch blocks from core during catch-up; the pruner needs time to
+	// remove data outside the availability window.
 	for _, pruned := range pruningFulls {
 		for _, b := range archivalBlobs {
-			has, err := pruned.EDSStore.HasByHeight(ctx, b.height)
-			require.NoError(t, err)
-			assert.False(t, has)
+			assert.Eventually(t, func() bool {
+				has, err := pruned.EDSStore.HasByHeight(ctx, b.height)
+				return err == nil && !has
+			}, 30*time.Second, 500*time.Millisecond,
+				"expected EDS at height %d to be pruned", b.height)
 		}
 	}