Wire reactive islands end-to-end: live interactive demos on the demo page

- Rebuild sx-browser.js with signals spec module (was missing entirely)
- Register signal functions (signal, deref, effect, computed, etc.) as
  PRIMITIVES so runtime-evaluated SX code in island bodies can call them
- Add reactive deref detection in adapter-dom.sx: (deref sig) in island
  scope creates reactive-text node instead of static text
- Add Island SSR support in html.py (_render_island with data-sx-island)
- Add Island bundling in jinja_bridge.py (defisland defs sent to client)
- Update deps.py to track Island dependencies alongside Component
- Add defisland to _ASER_FORMS in async_eval.py
- Add clear-interval platform primitive (was missing)
- Create four live demo islands: counter, temperature, imperative, stopwatch

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

shared/sx/jinja_bridge.py

@@ -25,7 +25,7 @@ import hashlib
 import os
 from typing import Any
 
-from .types import NIL, Component, Keyword, Macro, Symbol
+from .types import NIL, Component, Island, Keyword, Macro, Symbol
 from .parser import parse
 import os as _os
 if _os.environ.get("SX_USE_REF") == "1":
@@ -64,7 +64,14 @@ def _compute_component_hash() -> None:
     parts = []
     for key in sorted(_COMPONENT_ENV):
         val = _COMPONENT_ENV[key]
-        if isinstance(val, Component):
+        if isinstance(val, Island):
+            param_strs = ["&key"] + list(val.params)
+            if val.has_children:
+                param_strs.extend(["&rest", "children"])
+            params_sx = "(" + " ".join(param_strs) + ")"
+            body_sx = serialize(val.body)
+            parts.append(f"(defisland ~{val.name} {params_sx} {body_sx})")
+        elif isinstance(val, Component):
             param_strs = ["&key"] + list(val.params)
             if val.has_children:
                 param_strs.extend(["&rest", "children"])
@@ -198,7 +205,7 @@ def register_components(sx_source: str) -> None:
     # Slightly over-counts per component but safe and avoids re-scanning at request time.
     all_classes: set[str] | None = None
     for key, val in _COMPONENT_ENV.items():
-        if key not in existing and isinstance(val, Component):
+        if key not in existing and isinstance(val, (Component, Island)):
             if all_classes is None:
                 all_classes = scan_classes_from_sx(sx_source)
             val.css_classes = set(all_classes)
@@ -307,7 +314,16 @@ def client_components_tag(*names: str) -> str:
     from .parser import serialize
     parts = []
     for key, val in _COMPONENT_ENV.items():
-        if isinstance(val, Component):
+        if isinstance(val, Island):
+            if names and val.name not in names and key.lstrip("~") not in names:
+                continue
+            param_strs = ["&key"] + list(val.params)
+            if val.has_children:
+                param_strs.extend(["&rest", "children"])
+            params_sx = "(" + " ".join(param_strs) + ")"
+            body_sx = serialize(val.body, pretty=True)
+            parts.append(f"(defisland ~{val.name} {params_sx} {body_sx})")
+        elif isinstance(val, Component):
             if names and val.name not in names and key.lstrip("~") not in names:
                 continue
             # Reconstruct defcomp source from the Component object
@@ -365,7 +381,15 @@ def components_for_page(page_sx: str, service: str | None = None) -> tuple[str,
     # Also include macros — they're needed for client-side expansion
     parts = []
     for key, val in _COMPONENT_ENV.items():
-        if isinstance(val, Component):
+        if isinstance(val, Island):
+            if f"~{val.name}" in needed or key in needed:
+                param_strs = ["&key"] + list(val.params)
+                if val.has_children:
+                    param_strs.extend(["&rest", "children"])
+                params_sx = "(" + " ".join(param_strs) + ")"
+                body_sx = serialize(val.body, pretty=True)
+                parts.append(f"(defisland ~{val.name} {params_sx} {body_sx})")
+        elif isinstance(val, Component):
             if f"~{val.name}" in needed or key in needed:
                 param_strs = ["&key"] + list(val.params)
                 if val.has_children:
@@ -412,7 +436,7 @@ def css_classes_for_page(page_sx: str, service: str | None = None) -> set[str]:
     classes: set[str] = set()
 
     for key, val in _COMPONENT_ENV.items():
-        if isinstance(val, Component):
+        if isinstance(val, (Component, Island)):
             if (f"~{val.name}" in needed or key in needed) and val.css_classes:
                 classes.update(val.css_classes)