fix(html): normalise nil render context

Co-Authored-By: Virgil <virgil@lethean.io>

context.go

@@ -33,6 +33,15 @@ func applyLocaleToService(svc Translator, locale string) {
 	}
 }
 
+// normaliseContext ensures render paths always have a usable context.
+// A nil input is replaced with a fresh default context.
+func normaliseContext(ctx *Context) *Context {
+	if ctx != nil {
+		return ctx
+	}
+	return NewContext()
+}
+
 // context.go: NewContext creates a new rendering context with sensible defaults.
 // Example: ctx := NewContext("en-GB").
 // An optional locale may be provided as the first argument.

layout.go

@@ -133,6 +133,7 @@ func (l *Layout) Render(ctx *Context) string {
 	if l == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	var b strings.Builder
 

layout_test.go

@@ -226,3 +226,15 @@ func TestLayout_RenderNilReceiver(t *testing.T) {
 		t.Fatalf("nil Layout should render empty string, got %q", got)
 	}
 }
+
+func TestLayout_RenderNilContext(t *testing.T) {
+	layout := NewLayout("C").C(Raw("content"))
+	got := layout.Render(nil)
+
+	if !strings.Contains(got, `data-block="C-0"`) {
+		t.Fatalf("Layout.Render(nil) should still render the block ID, got:\n%s", got)
+	}
+	if !strings.Contains(got, "content") {
+		t.Fatalf("Layout.Render(nil) should still render content, got:\n%s", got)
+	}
+}

node.go

@@ -34,7 +34,7 @@ func renderNode(n Node, ctx *Context) string {
 	if n == nil {
 		return ""
 	}
-	return n.Render(ctx)
+	return n.Render(normaliseContext(ctx))
 }
 
 // renderNodeWithPath renders a node while preserving layout path prefixes for
@@ -43,6 +43,7 @@ func renderNodeWithPath(n Node, ctx *Context, path string) string {
 	if n == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	switch t := n.(type) {
 	case *Layout:
@@ -246,7 +247,7 @@ func (n *elNode) Render(ctx *Context) string {
 		return ""
 	}
 
-	return n.renderWithPath(ctx, "")
+	return n.renderWithPath(normaliseContext(ctx), "")
 }
 
 func (n *elNode) renderWithPath(ctx *Context, path string) string {
@@ -312,9 +313,10 @@ func (n *textNode) Render(ctx *Context) string {
 	if n == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	var text string
-	if ctx != nil && ctx.service != nil {
+	if ctx.service != nil {
 		text = ctx.service.T(n.key, n.args...)
 	} else {
 		text = i18n.T(n.key, n.args...)
@@ -339,9 +341,10 @@ func (n *ifNode) Render(ctx *Context) string {
 	if n == nil || n.cond == nil || n.node == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	if n.cond(ctx) {
-		return n.node.Render(ctx)
+		return renderNodeWithPath(n.node, ctx, "")
 	}
 	return ""
 }
@@ -363,9 +366,10 @@ func (n *unlessNode) Render(ctx *Context) string {
 	if n == nil || n.cond == nil || n.node == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	if !n.cond(ctx) {
-		return n.node.Render(ctx)
+		return renderNodeWithPath(n.node, ctx, "")
 	}
 	return ""
 }
@@ -389,11 +393,12 @@ func (n *entitledNode) Render(ctx *Context) string {
 	if n == nil || n.node == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
-	if ctx == nil || ctx.Entitlements == nil || !ctx.Entitlements(n.feature) {
+	if ctx.Entitlements == nil || !ctx.Entitlements(n.feature) {
 		return ""
 	}
-	return n.node.Render(ctx)
+	return renderNodeWithPath(n.node, ctx, "")
 }
 
 // --- switchNode ---
@@ -413,10 +418,11 @@ func (n *switchNode) Render(ctx *Context) string {
 	if n == nil || n.selector == nil || n.cases == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	key := n.selector(ctx)
 	if node, ok := n.cases[key]; ok {
-		return renderNode(node, ctx)
+		return renderNodeWithPath(node, ctx, "")
 	}
 	return ""
 }
@@ -444,10 +450,11 @@ func (n *eachNode[T]) Render(ctx *Context) string {
 	if n == nil || n.items == nil || n.fn == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	var b strings.Builder
 	for item := range n.items {
-		b.WriteString(renderNode(n.fn(item), ctx))
+		b.WriteString(renderNodeWithPath(n.fn(item), ctx, ""))
 	}
 	return b.String()
 }

pipeline.go

@@ -48,9 +48,7 @@ func StripTags(html string) string {
 // and returns a GrammarImprint — the full render-reverse pipeline.
 // Example: Imprint(NewLayout("C").C(Text("page.body")), NewContext()).
 func Imprint(node Node, ctx *Context) reversal.GrammarImprint {
-	if ctx == nil {
-		ctx = NewContext()
-	}
+	ctx = normaliseContext(ctx)
 	rendered := Render(node, ctx)
 	text := StripTags(rendered)
 	tok := reversal.NewTokeniser()
@@ -62,9 +60,7 @@ func Imprint(node Node, ctx *Context) reversal.GrammarImprint {
 // and returns pairwise similarity scores. Key format: "name1:name2".
 // Example: CompareVariants(NewResponsive().Variant("desktop", NewLayout("C")), NewContext()).
 func CompareVariants(r *Responsive, ctx *Context) map[string]float64 {
-	if ctx == nil {
-		ctx = NewContext()
-	}
+	ctx = normaliseContext(ctx)
 	if r == nil {
 		return map[string]float64{}
 	}

render.go

@@ -3,9 +3,7 @@ package html
 // render.go: Render is a convenience function that renders a node tree to HTML.
 // Example: Render(NewLayout("C").C(Raw("body")), NewContext()).
 func Render(node Node, ctx *Context) string {
-	if ctx == nil {
-		ctx = NewContext()
-	}
+	ctx = normaliseContext(ctx)
 	if node == nil {
 		return ""
 	}

responsive.go

@@ -106,6 +106,7 @@ func (r *Responsive) Render(ctx *Context) string {
 	if r == nil {
 		return ""
 	}
+	ctx = normaliseContext(ctx)
 
 	var b strings.Builder
 	for _, v := range r.variants {

responsive_test.go

@@ -96,6 +96,20 @@ func TestResponsive_RenderNilReceiver(t *testing.T) {
 	}
 }
 
+func TestResponsive_RenderNilContext(t *testing.T) {
+	r := NewResponsive().
+		Variant("desktop", NewLayout("C").C(Raw("main")))
+
+	got := r.Render(nil)
+
+	if !strings.Contains(got, `data-variant="desktop"`) {
+		t.Fatalf("Responsive.Render(nil) should still render the variant wrapper, got:\n%s", got)
+	}
+	if !strings.Contains(got, `data-block="C-0"`) {
+		t.Fatalf("Responsive.Render(nil) should still render the layout block, got:\n%s", got)
+	}
+}
+
 func TestResponsive_NilLayoutVariant(t *testing.T) {
 	ctx := NewContext()
 	r := NewResponsive().