Add Phase 2 P1 features: reactive class/style, refs, portals

- :class-map dict toggles classes reactively via classList.add/remove
- :style-map dict sets inline styles reactively via el.style[prop]
- ref/ref-get/ref-set! mutable boxes (non-reactive, like useRef)
- :ref attribute sets ref.current to DOM element after rendering
- portal render-dom form renders children into remote target element
- Portal content auto-removed on island disposal via register-in-scope
- Added #portal-root div to page shell template
- Added stop-propagation and dom-focus platform functions
- Demo islands for all three features on the demo page
- Updated status tables: all P0/P1 features marked Done

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

shared/sx/ref/adapter-dom.sx

@@ -185,6 +185,15 @@
                     ;; Two-way input binding: :bind signal
                     (and (= attr-name "bind") (signal? attr-val))
                       (bind-input el attr-val)
+                    ;; class-map: reactively toggle classes
+                    (= attr-name "class-map")
+                      (reactive-class-map el attr-val)
+                    ;; style-map: reactively set inline styles
+                    (= attr-name "style-map")
+                      (reactive-style-map el attr-val)
+                    ;; ref: set ref.current to this element
+                    (= attr-name "ref")
+                      (ref-set! attr-val el)
                     ;; Boolean attr
                     (contains? BOOLEAN_ATTRS attr-name)
                       (when attr-val (dom-set-attr el attr-name ""))
@@ -306,7 +315,7 @@
 (define RENDER_DOM_FORMS
   (list "if" "when" "cond" "case" "let" "let*" "begin" "do"
         "define" "defcomp" "defisland" "defmacro" "defstyle" "defhandler"
-        "map" "map-indexed" "filter" "for-each"))
+        "map" "map-indexed" "filter" "for-each" "portal"))
 
 (define render-dom-form?
   (fn (name)
@@ -423,6 +432,10 @@
       (= name "filter")
         (render-to-dom (trampoline (eval-expr expr env)) env ns)
 
+      ;; portal — render children into a remote target element
+      (= name "portal")
+        (render-dom-portal args env ns)
+
       ;; for-each (render variant)
       (= name "for-each")
         (let ((f (trampoline (eval-expr (nth expr 1) env)))
@@ -700,6 +713,86 @@
             (reset! sig (dom-get-prop el "value"))))))))
 
 
+;; --------------------------------------------------------------------------
+;; reactive-class-map — toggle classes based on signals
+;; --------------------------------------------------------------------------
+;;
+;; Dict values should be signals or booleans. Signals are deref'd reactively.
+;;
+;; (div :class-map (dict "active" selected? "hidden" hide-computed))
+;;
+;; Creates a single effect that deref's each value (tracking signal deps)
+;; and calls classList.add/remove for each class.
+
+(define reactive-class-map
+  (fn (el class-dict)
+    (effect (fn ()
+      (for-each
+        (fn (cls)
+          (let ((val (deref (get class-dict cls))))
+            (if val
+              (dom-add-class el cls)
+              (dom-remove-class el cls))))
+        (keys class-dict))))))
+
+
+;; --------------------------------------------------------------------------
+;; reactive-style-map — reactively set inline styles via signals
+;; --------------------------------------------------------------------------
+;;
+;; Dict values should be signals or strings. Signals are deref'd reactively.
+;;
+;; (div :style-map (dict "width" width-sig "opacity" opacity-computed))
+;;
+;; Creates a single effect that deref's each value and sets the style property.
+
+(define reactive-style-map
+  (fn (el style-dict)
+    (effect (fn ()
+      (for-each
+        (fn (prop)
+          (dom-set-style el prop (str (deref (get style-dict prop)))))
+        (keys style-dict))))))
+
+
+;; --------------------------------------------------------------------------
+;; render-dom-portal — render children into a remote target element
+;; --------------------------------------------------------------------------
+;;
+;; (portal "#modal-root" (div "content"))
+;;
+;; Renders children into the DOM node matched by the selector, rather than
+;; into the current position. Returns a comment marker at the original
+;; position. Registers a disposer to clean up portal content on island
+;; teardown.
+
+(define render-dom-portal
+  (fn (args env ns)
+    (let ((selector (trampoline (eval-expr (first args) env)))
+          (target (dom-query selector)))
+      (if (not target)
+        ;; Target not found — render nothing, log warning
+        (do
+          (log-warn (str "Portal target not found: " selector))
+          (create-comment (str "portal: " selector " (not found)")))
+        (let ((marker (create-comment (str "portal: " selector)))
+              (frag (create-fragment)))
+          ;; Render children into the fragment
+          (for-each
+            (fn (child) (dom-append frag (render-to-dom child env ns)))
+            (rest args))
+          ;; Track portal nodes for disposal
+          (let ((portal-nodes (dom-child-nodes frag)))
+            ;; Append into remote target
+            (dom-append target frag)
+            ;; Register disposer: remove portal content on island teardown
+            (register-in-scope
+              (fn ()
+                (for-each (fn (n) (dom-remove n)) portal-nodes))))
+          ;; Return marker at original position
+          marker)))))
+
+
 ;; --------------------------------------------------------------------------
 ;; Platform interface — DOM adapter
 ;; --------------------------------------------------------------------------
@@ -724,6 +817,20 @@
 ;;   (dom-set-data el key val)    → void (store arbitrary data on element)
 ;;   (dom-get-data el key)        → any (retrieve data stored on element)
 ;;
+;; Property access (for input binding):
+;;   (dom-set-prop el name val)   → void (set JS property: el[name] = val)
+;;   (dom-get-prop el name)       → any (read JS property: el[name])
+;;
+;; Class manipulation (for reactive class-map):
+;;   (dom-add-class el cls)       → void (classList.add)
+;;   (dom-remove-class el cls)    → void (classList.remove)
+;;
+;; Style manipulation (for reactive style-map):
+;;   (dom-set-style el prop val)  → void (el.style[prop] = val)
+;;
+;; Query (for portals):
+;;   (dom-query selector)         → Element or nil (document.querySelector)
+;;
 ;; Event handling:
 ;;   (dom-listen el name handler) → remove-fn (addEventListener, returns remover)
 ;;   (dom-dispatch el name detail)→ boolean (dispatch CustomEvent, bubbles: true)
@@ -748,7 +855,11 @@
 ;;
 ;; From signals.sx:
 ;;   signal, deref, reset!, swap!, computed, effect, batch
-;;   signal?, with-island-scope
+;;   signal?, with-island-scope, register-in-scope
+;;   ref, ref-get, ref-set!
+;;
+;; Pure primitives used:
+;;   keys, get, str
 ;;
 ;; Iteration:
 ;;   (for-each-indexed fn coll) → call fn(index, item) for each element

shared/sx/ref/bootstrap_js.py

@@ -444,6 +444,8 @@ class JSEmitter:
             "dom-outer-html": "domOuterHtml",
             "dom-body-inner-html": "domBodyInnerHtml",
             "prevent-default": "preventDefault_",
+            "stop-propagation": "stopPropagation_",
+            "dom-focus": "domFocus",
             "element-value": "elementValue",
             "validate-for-request": "validateForRequest",
             "with-transition": "withTransition",
@@ -3461,6 +3463,8 @@ PLATFORM_ORCHESTRATION_JS = """
   // --- Events ---
 
   function preventDefault_(e) { if (e && e.preventDefault) e.preventDefault(); }
+  function stopPropagation_(e) { if (e && e.stopPropagation) e.stopPropagation(); }
+  function domFocus(el) { if (el && el.focus) el.focus(); }
   function elementValue(el) { return el && el.value !== undefined ? el.value : NIL; }
 
   function domAddListener(el, event, fn, opts) {

shared/sx/ref/signals.sx

@@ -306,7 +306,28 @@
 
 
 ;; ==========================================================================
-;; 12. Named stores — page-level signal containers (L3)
+;; 12. Refs — mutable boxes, no reactivity
+;; ==========================================================================
+;;
+;; A ref is a mutable container that does NOT trigger subscriptions when
+;; written. Like React's useRef: holds mutable values between renders, and
+;; provides imperative DOM element access via :ref attribute.
+
+(define ref
+  (fn (initial)
+    (dict "current" initial)))
+
+(define ref-get
+  (fn (r)
+    (get r "current")))
+
+(define ref-set!
+  (fn (r v)
+    (dict-set! r "current" v)))
+
+
+;; ==========================================================================
+;; 13. Named stores — page-level signal containers (L3)
 ;; ==========================================================================
 ;;
 ;; Stores persist across island creation/destruction. They live at page