feat(html): add tabindex helper

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

docs/architecture.md

@@ -32,6 +32,13 @@ All concrete node types are unexported structs with exported constructor functio
 | `Switch(selector, cases)` | Renders one of several named cases based on a runtime selector function. Returns empty string when no case matches. |
 | `Entitled(feature, Node)` | Renders the child only when the context's entitlement function grants the named feature. Deny-by-default: returns empty string when no entitlement function is set. |
 
+Accessibility-oriented helpers are also provided for common attribute patterns:
+
+- `AriaLabel(node, label)`
+- `Alt(node, text)`
+- `AriaHidden(node, hidden)`
+- `TabIndex(node, index)`
+
 ### Safety Guarantees
 
 - **XSS prevention**: `Text()` nodes always HTML-escape their output via `html.EscapeString()`. User-supplied strings passed through `Text()` cannot inject HTML.

docs/history.md

@@ -114,6 +114,6 @@ These are not regressions; they are design choices or deferred work recorded for
 These items were captured during the WASM size reduction work and expert review sessions. They are not committed work items.
 
 - **TypeScript type definitions** alongside `GenerateBundle()` for typed Web Component consumers.
-- **Accessibility helpers** — `aria-label` builder, `alt` text helpers, focus management nodes. The layout has semantic HTML and ARIA roles but no API for fine-grained accessibility attributes beyond `Attr()`.
+- **Accessibility helpers** — `aria-label`, `alt`, `aria-hidden`, and `tabindex` helpers. The layout has semantic HTML and ARIA roles, and the node layer now exposes common accessibility attribute shortcuts beyond `Attr()`.
 - **Layout variant validation** — return a warning or sentinel error from `NewLayout` when the variant string contains unrecognised slot characters.
 - **Daemon mode for codegen** — watch mode for regenerating the JS bundle when slot config changes, for development workflows.

node.go

@@ -5,6 +5,7 @@ import (
 	"iter"
 	"maps"
 	"slices"
+	"strconv"
 	"strings"
 
 	i18n "dappco.re/go/core/i18n"
@@ -115,6 +116,11 @@ func AriaHidden(n Node, hidden bool) Node {
 	return Attr(n, "aria-hidden", "false")
 }
 
+// TabIndex sets the tabindex attribute on an element node.
+func TabIndex(n Node, index int) Node {
+	return Attr(n, "tabindex", strconv.Itoa(index))
+}
+
 func (n *elNode) Render(ctx *Context) string {
 	var b strings.Builder
 

node_test.go

@@ -211,6 +211,15 @@ func TestAriaHiddenHelper(t *testing.T) {
 	}
 }
 
+func TestTabIndexHelper(t *testing.T) {
+	ctx := NewContext()
+	node := TabIndex(El("button", Raw("action")), -1)
+	got := node.Render(ctx)
+	if !strings.Contains(got, `tabindex="-1"`) {
+		t.Errorf("TabIndex() = %q, want tabindex=\"-1\"", got)
+	}
+}
+
 func TestElNode_MultipleAttrs(t *testing.T) {
 	ctx := NewContext()
 	node := Attr(Attr(El("a", Raw("link")), "href", "/home"), "class", "nav")