feat(diff): give the diff header its own white/gray identity

pkg/action/action.go

@@ -170,9 +170,10 @@ func DiffHeader(breadcrumb []string, target string, color bool) string {
 }
 
 // diffTurnBanner heads one bulk turn: the root module as an inverted "≡ … ≡" chip
-// (mirroring the log's root section header) followed by the turn's instance name
-// in bold. This is the anchor the eye lands on, so turn boundaries stand out in a
-// long batch. Callers put the separating blank line above the whole header block.
+// followed by the turn's instance name in bold. The chip is white rather than the
+// run log's indigo root color, so the banner reads as "this is the diff" and not
+// more run output. It is the anchor the eye lands on, so turn boundaries stand out
+// in a long batch. Callers put the separating blank line above the header block.
 func diffTurnBanner(root, turn string, color bool) string {
 	if color {
 		return diffColorInvert + diffColorRoot + diffColorBold + " ≡ " + root + " ≡ " + diffColorReset +
@@ -184,18 +185,20 @@ func diffTurnBanner(root, turn string, color bool) string {
 // diffHandoffChain renders the submodule hand-off lines beneath a turn banner:
 // one "▸ parent › child" per descent step from the turn down to the leaf, the
 // run log's nested-dispatch form — no root chip, so headers inside a turn read
-// lighter. The marker and parent share the worker teal so the hand-off reads as
-// one legible breadcrumb unit rather than fading into the diff; the child, the
-// step that matters, stays bold. Empty when the breadcrumb stops at the turn.
+// lighter. The child — the module that produced the diff — is an inverted light-
+// gray chip: a filled anchor so the breadcrumb stands out against the diff, one
+// step below the white turn chip, and in neither the log's indigo nor teal so it
+// never reads as more run output. The marker and parent stay muted context.
+// Empty when the breadcrumb stops at the turn.
 func diffHandoffChain(segs []string, color bool) string {
 	var b strings.Builder
 	for i := 1; i+1 < len(segs); i++ {
 		parent, child := segs[i], segs[i+1]
 		if color {
-			b.WriteString(diffColorWorker + "▸ " + parent + " › " + diffColorReset +
-				diffColorBold + child + diffColorReset + "\n")
+			b.WriteString(diffColorMuted + "▸ " + parent + " › " + diffColorReset +
+				diffColorInvert + diffColorSub + " " + child + " " + diffColorReset + "\n")
 		} else {
-			b.WriteString("▸ " + parent + " › " + child + "\n")
+			b.WriteString("▸ " + parent + " › [" + child + "]\n")
 		}
 	}
 	return b.String()

pkg/action/diff.go

@@ -16,9 +16,9 @@ const (
 	diffColorGreen  = "\033[32m"
 	diffColorCyan   = "\033[36m"
 	diffColorInvert = "\033[7m"
-	diffColorMuted  = "\033[38;5;244m" // mid gray — matches the log handler's muted tone
-	diffColorRoot   = "\033[38;5;61m"  // muted indigo — the orchestrator chip (log's root color)
-	diffColorWorker = "\033[38;5;66m"  // slate teal — the hand-off marker (log's worker color)
+	diffColorMuted  = "\033[38;5;244m" // mid gray — the hand-off marker, parent context, and target line
+	diffColorRoot   = "\033[38;5;231m" // white — the turn chip, top of the diff header
+	diffColorSub    = "\033[38;5;250m" // light gray — the submodule chip, one step below the turn
 )
 
 // printDiff computes a unified diff between old and new content and hands it to

pkg/action/diff_header_test.go

@@ -32,7 +32,7 @@ func TestDiffHeader_SubmoduleGetsRootFreeHandoff(t *testing.T) {
 	// root and item, then a "▸ item › submodule" hand-off with no root chip.
 	got := DiffHeader([]string{"bulk-deploy-k8s", "deploy-k8s-2", "autocert"}, "acme/cluster-2 (main)", false)
 	want := "\n[≡ bulk-deploy-k8s ≡] deploy-k8s-2\n" +
-		"▸ deploy-k8s-2 › autocert\n" +
+		"▸ deploy-k8s-2 › [autocert]\n" +
 		"acme/cluster-2 (main)\n"
 	if got != want {
 		t.Errorf("got %q, want %q", got, want)
@@ -44,8 +44,8 @@ func TestDiffHeader_ColorTurnBannerAndHandoff(t *testing.T) {
 	want := "\n" +
 		diffColorInvert + diffColorRoot + diffColorBold + " ≡ deps-bump ≡ " + diffColorReset +
 		" " + diffColorBold + "service-a" + diffColorReset + "\n" +
-		diffColorWorker + "▸ service-a › " + diffColorReset +
-		diffColorBold + "autocert" + diffColorReset + "\n" +
+		diffColorMuted + "▸ service-a › " + diffColorReset +
+		diffColorInvert + diffColorSub + " autocert " + diffColorReset + "\n" +
 		diffColorMuted + "acme/service-a" + diffColorReset + "\n"
 	if got != want {
 		t.Errorf("got %q, want %q", got, want)
@@ -106,15 +106,15 @@ func TestDiffCollector_BannerOncePerTurnHandoffPerSubmodule(t *testing.T) {
 		t.Errorf("expected deploy-1 named 3 times, got %d:\n%s", n, out)
 	}
 	for _, want := range []string{
-		"▸ deploy-1 › autocert", "▸ deploy-1 › ingress", "▸ deploy-2 › autocert",
+		"▸ deploy-1 › [autocert]", "▸ deploy-1 › [ingress]", "▸ deploy-2 › [autocert]",
 	} {
 		if !strings.Contains(out, want) {
 			t.Errorf("expected hand-off %q, got:\n%s", want, out)
 		}
 	}
 	// Every header block is set off from the diff above it by a blank line, so a
 	// breadcrumb between two diffs stays visible — the within-turn submodule too.
-	if !strings.Contains(out, "\n\n▸ deploy-1 › ingress") {
+	if !strings.Contains(out, "\n\n▸ deploy-1 › [ingress]") {
 		t.Errorf("expected a blank line before the within-turn submodule header, got:\n%s", out)
 	}
 }