Bootstrap stores + event bridge, add island hydration to boot.sx

- signals.sx: fix has? → has-key?, add def-store/use-store/clear-stores
  (L3 named stores), emit-event/on-event/bridge-event (event bridge)
- boot.sx: add sx-hydrate-islands, hydrate-island, dispose-island
  for client-side island hydration from SSR output
- bootstrap_js.py: add RENAMES, platform fns (domListen, eventDetail,
  domGetData, jsonParse), public API exports for all new functions
- bootstrap_py.py: add RENAMES, server-side no-op stubs for DOM events
- Regenerate sx-ref.js (with boot adapter) and sx_ref.py
- Update reactive-islands status: hydration, stores, bridge all spec'd

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

shared/static/scripts/sx-ref.js

@@ -14,7 +14,7 @@
   // =========================================================================
 
   var NIL = Object.freeze({ _nil: true, toString: function() { return "nil"; } });
-  var SX_VERSION = "2026-03-08T10:13:40Z";
+  var SX_VERSION = "2026-03-08T11:12:31Z";
 
   function isNil(x) { return x === NIL || x === null || x === undefined; }
   function isSxTruthy(x) { return x !== false && !isNil(x); }
@@ -572,6 +572,92 @@
     return makeThunk(componentBody(comp), local);
   };
 
+  // =========================================================================
+  // Platform: deps module — component dependency analysis
+  // =========================================================================
+
+  function componentDeps(c) {
+    return c.deps ? c.deps.slice() : [];
+  }
+
+  function componentSetDeps(c, deps) {
+    c.deps = deps;
+  }
+
+  function componentCssClasses(c) {
+    return c.cssClasses ? c.cssClasses.slice() : [];
+  }
+
+  function envComponents(env) {
+    var names = [];
+    for (var k in env) {
+      var v = env[k];
+      if (v && (v._component || v._macro)) names.push(k);
+    }
+    return names;
+  }
+
+  function regexFindAll(pattern, source) {
+    var re = new RegExp(pattern, "g");
+    var results = [];
+    var m;
+    while ((m = re.exec(source)) !== null) {
+      if (m[1] !== undefined) results.push(m[1]);
+      else results.push(m[0]);
+    }
+    return results;
+  }
+
+  function scanCssClasses(source) {
+    var classes = {};
+    var result = [];
+    var m;
+    var re1 = /:class\s+"([^"]*)"/g;
+    while ((m = re1.exec(source)) !== null) {
+      var parts = m[1].split(/\s+/);
+      for (var i = 0; i < parts.length; i++) {
+        if (parts[i] && !classes[parts[i]]) {
+          classes[parts[i]] = true;
+          result.push(parts[i]);
+        }
+      }
+    }
+    var re2 = /:class\s+\(str\s+((?:"[^"]*"\s*)+)\)/g;
+    while ((m = re2.exec(source)) !== null) {
+      var re3 = /"([^"]*)"/g;
+      var m2;
+      while ((m2 = re3.exec(m[1])) !== null) {
+        var parts2 = m2[1].split(/\s+/);
+        for (var j = 0; j < parts2.length; j++) {
+          if (parts2[j] && !classes[parts2[j]]) {
+            classes[parts2[j]] = true;
+            result.push(parts2[j]);
+          }
+        }
+      }
+    }
+    var re4 = /;;\s*@css\s+(.+)/g;
+    while ((m = re4.exec(source)) !== null) {
+      var parts3 = m[1].split(/\s+/);
+      for (var k = 0; k < parts3.length; k++) {
+        if (parts3[k] && !classes[parts3[k]]) {
+          classes[parts3[k]] = true;
+          result.push(parts3[k]);
+        }
+      }
+    }
+    return result;
+  }
+
+  function componentIoRefs(c) {
+    return c.ioRefs ? c.ioRefs.slice() : [];
+  }
+
+  function componentSetIoRefs(c, refs) {
+    c.ioRefs = refs;
+  }
+
+
   // =========================================================================
   // Platform interface — Parser
   // =========================================================================
@@ -2179,6 +2265,93 @@ return (function() {
 })() : NIL);
 })(); };
 
+  // _optimistic-snapshots
+  var _optimisticSnapshots = {};
+
+  // optimistic-cache-update
+  var optimisticCacheUpdate = function(cacheKey, mutator) { return (function() {
+  var cached = pageDataCacheGet(cacheKey);
+  return (isSxTruthy(cached) ? (function() {
+  var predicted = mutator(cached);
+  _optimisticSnapshots[cacheKey] = cached;
+  pageDataCacheSet(cacheKey, predicted);
+  return predicted;
+})() : NIL);
+})(); };
+
+  // optimistic-cache-revert
+  var optimisticCacheRevert = function(cacheKey) { return (function() {
+  var snapshot = get(_optimisticSnapshots, cacheKey);
+  return (isSxTruthy(snapshot) ? (pageDataCacheSet(cacheKey, snapshot), dictDelete(_optimisticSnapshots, cacheKey), snapshot) : NIL);
+})(); };
+
+  // optimistic-cache-confirm
+  var optimisticCacheConfirm = function(cacheKey) { return dictDelete(_optimisticSnapshots, cacheKey); };
+
+  // submit-mutation
+  var submitMutation = function(pageName, params, actionName, payload, mutatorFn, onComplete) { return (function() {
+  var cacheKey = pageDataCacheKey(pageName, params);
+  var predicted = optimisticCacheUpdate(cacheKey, mutatorFn);
+  if (isSxTruthy(predicted)) {
+  tryRerenderPage(pageName, params, predicted);
+}
+  return executeAction(actionName, payload, function(result) { if (isSxTruthy(result)) {
+  pageDataCacheSet(cacheKey, result);
+}
+optimisticCacheConfirm(cacheKey);
+if (isSxTruthy(result)) {
+  tryRerenderPage(pageName, params, result);
+}
+logInfo((String("sx:optimistic confirmed ") + String(pageName)));
+return (isSxTruthy(onComplete) ? onComplete("confirmed") : NIL); }, function(error) { return (function() {
+  var reverted = optimisticCacheRevert(cacheKey);
+  if (isSxTruthy(reverted)) {
+  tryRerenderPage(pageName, params, reverted);
+}
+  logWarn((String("sx:optimistic reverted ") + String(pageName) + String(": ") + String(error)));
+  return (isSxTruthy(onComplete) ? onComplete("reverted") : NIL);
+})(); });
+})(); };
+
+  // _is-online
+  var _isOnline = true;
+
+  // _offline-queue
+  var _offlineQueue = [];
+
+  // offline-is-online?
+  var offlineIsOnline_p = function() { return _isOnline; };
+
+  // offline-set-online!
+  var offlineSetOnline_b = function(val) { return (_isOnline = val); };
+
+  // offline-queue-mutation
+  var offlineQueueMutation = function(actionName, payload, pageName, params, mutatorFn) { return (function() {
+  var cacheKey = pageDataCacheKey(pageName, params);
+  var entry = {["action"]: actionName, ["payload"]: payload, ["page"]: pageName, ["params"]: params, ["timestamp"]: nowMs(), ["status"]: "pending"};
+  _offlineQueue.push(entry);
+  (function() {
+  var predicted = optimisticCacheUpdate(cacheKey, mutatorFn);
+  return (isSxTruthy(predicted) ? tryRerenderPage(pageName, params, predicted) : NIL);
+})();
+  logInfo((String("sx:offline queued ") + String(actionName) + String(" (") + String(len(_offlineQueue)) + String(" pending)")));
+  return entry;
+})(); };
+
+  // offline-sync
+  var offlineSync = function() { return (function() {
+  var pending = filter(function(e) { return (get(e, "status") == "pending"); }, _offlineQueue);
+  return (isSxTruthy(!isSxTruthy(isEmpty(pending))) ? (logInfo((String("sx:offline syncing ") + String(len(pending)) + String(" mutations"))), forEach(function(entry) { return executeAction(get(entry, "action"), get(entry, "payload"), function(result) { entry["status"] = "synced";
+return logInfo((String("sx:offline synced ") + String(get(entry, "action")))); }, function(error) { entry["status"] = "failed";
+return logWarn((String("sx:offline sync failed ") + String(get(entry, "action")) + String(": ") + String(error))); }); }, pending)) : NIL);
+})(); };
+
+  // offline-pending-count
+  var offlinePendingCount = function() { return len(filter(function(e) { return (get(e, "status") == "pending"); }, _offlineQueue)); };
+
+  // offline-aware-mutation
+  var offlineAwareMutation = function(pageName, params, actionName, payload, mutatorFn, onComplete) { return (isSxTruthy(_isOnline) ? submitMutation(pageName, params, actionName, payload, mutatorFn, onComplete) : (offlineQueueMutation(actionName, payload, pageName, params, mutatorFn), (isSxTruthy(onComplete) ? onComplete("queued") : NIL))); };
+
   // current-page-layout
   var currentPageLayout = function() { return (function() {
   var pathname = urlPathname(browserLocationHref());
@@ -2382,7 +2555,8 @@ return bindInlineHandlers(root); };
   domAppend(el, node);
   hoistHeadElementsFull(el);
   processElements(el);
-  return sxHydrateElements(el);
+  sxHydrateElements(el);
+  return sxHydrateIslands(el);
 })() : NIL);
 })(); };
 
@@ -2397,6 +2571,7 @@ return (function() {
   { var _c = exprs; for (var _i = 0; _i < _c.length; _i++) { var expr = _c[_i]; domAppend(el, renderToDom(expr, env, NIL)); } }
   processElements(el);
   sxHydrateElements(el);
+  sxHydrateIslands(el);
   return domDispatch(el, "sx:resolved", {"id": id});
 })() : logWarn((String("resolveSuspense: no element for id=") + String(id))));
 })(); };
@@ -2491,8 +2666,186 @@ callExpr.push(dictGet(kwargs, k)); } }
   return logInfo((String("pages: ") + String(len(_pageRoutes)) + String(" routes loaded")));
 })(); };
 
+  // sx-hydrate-islands
+  var sxHydrateIslands = function(root) { return (function() {
+  var els = domQueryAll(sxOr(root, domBody()), "[data-sx-island]");
+  return forEach(function(el) { return (isSxTruthy(!isSxTruthy(isProcessed(el, "island-hydrated"))) ? (markProcessed(el, "island-hydrated"), hydrateIsland(el)) : NIL); }, els);
+})(); };
+
+  // hydrate-island
+  var hydrateIsland = function(el) { return (function() {
+  var name = domGetAttr(el, "data-sx-island");
+  var stateJson = sxOr(domGetAttr(el, "data-sx-state"), "{}");
+  return (function() {
+  var compName = (String("~") + String(name));
+  var env = getRenderEnv(NIL);
+  return (function() {
+  var comp = envGet(env, compName);
+  return (isSxTruthy(!isSxTruthy(sxOr(isComponent(comp), isIsland(comp)))) ? logWarn((String("hydrate-island: unknown island ") + String(compName))) : (function() {
+  var kwargs = jsonParse(stateJson);
+  var disposers = [];
+  var local = envMerge(componentClosure(comp), env);
+  { var _c = componentParams(comp); for (var _i = 0; _i < _c.length; _i++) { var p = _c[_i]; local[p] = (isSxTruthy(dictHas(kwargs, p)) ? dictGet(kwargs, p) : NIL); } }
+  return (function() {
+  var bodyDom = withIslandScope(function(disposable) { return append_b(disposers, disposable); }, function() { return renderToDom(componentBody(comp), local, NIL); });
+  morphChildren(el, bodyDom);
+  domSetData(el, "sx-disposers", disposers);
+  processElements(el);
+  return logInfo((String("hydrated island: ") + String(compName) + String(" (") + String(len(disposers)) + String(" disposers)")));
+})();
+})());
+})();
+})();
+})(); };
+
+  // dispose-island
+  var disposeIsland = function(el) { return (function() {
+  var disposers = domGetData(el, "sx-disposers");
+  return (isSxTruthy(disposers) ? (forEach(function(d) { return (isSxTruthy(isCallable(d)) ? d() : NIL); }, disposers), domSetData(el, "sx-disposers", NIL)) : NIL);
+})(); };
+
   // boot-init
-  var bootInit = function() { return (logInfo((String("sx-browser ") + String(SX_VERSION))), initCssTracking(), processPageScripts(), processSxScripts(NIL), sxHydrateElements(NIL), processElements(NIL)); };
+  var bootInit = function() { return (logInfo((String("sx-browser ") + String(SX_VERSION))), initCssTracking(), processPageScripts(), processSxScripts(NIL), sxHydrateElements(NIL), sxHydrateIslands(NIL), processElements(NIL)); };
+
+
+  // === Transpiled from deps (component dependency analysis) ===
+
+  // scan-refs
+  var scanRefs = function(node) { return (function() {
+  var refs = [];
+  scanRefsWalk(node, refs);
+  return refs;
+})(); };
+
+  // scan-refs-walk
+  var scanRefsWalk = function(node, refs) { return (isSxTruthy((typeOf(node) == "symbol")) ? (function() {
+  var name = symbolName(node);
+  return (isSxTruthy(startsWith(name, "~")) ? (isSxTruthy(!isSxTruthy(contains(refs, name))) ? append_b(refs, name) : NIL) : NIL);
+})() : (isSxTruthy((typeOf(node) == "list")) ? forEach(function(item) { return scanRefsWalk(item, refs); }, node) : (isSxTruthy((typeOf(node) == "dict")) ? forEach(function(key) { return scanRefsWalk(dictGet(node, key), refs); }, keys(node)) : NIL))); };
+
+  // transitive-deps-walk
+  var transitiveDepsWalk = function(n, seen, env) { return (isSxTruthy(!isSxTruthy(contains(seen, n))) ? (append_b(seen, n), (function() {
+  var val = envGet(env, n);
+  return (isSxTruthy((typeOf(val) == "component")) ? forEach(function(ref) { return transitiveDepsWalk(ref, seen, env); }, scanRefs(componentBody(val))) : (isSxTruthy((typeOf(val) == "macro")) ? forEach(function(ref) { return transitiveDepsWalk(ref, seen, env); }, scanRefs(macroBody(val))) : NIL));
+})()) : NIL); };
+
+  // transitive-deps
+  var transitiveDeps = function(name, env) { return (function() {
+  var seen = [];
+  var key = (isSxTruthy(startsWith(name, "~")) ? name : (String("~") + String(name)));
+  transitiveDepsWalk(key, seen, env);
+  return filter(function(x) { return !isSxTruthy((x == key)); }, seen);
+})(); };
+
+  // compute-all-deps
+  var computeAllDeps = function(env) { return forEach(function(name) { return (function() {
+  var val = envGet(env, name);
+  return (isSxTruthy((typeOf(val) == "component")) ? componentSetDeps(val, transitiveDeps(name, env)) : NIL);
+})(); }, envComponents(env)); };
+
+  // scan-components-from-source
+  var scanComponentsFromSource = function(source) { return (function() {
+  var matches = regexFindAll("\\(~([a-zA-Z_][a-zA-Z0-9_\\-]*)", source);
+  return map(function(m) { return (String("~") + String(m)); }, matches);
+})(); };
+
+  // components-needed
+  var componentsNeeded = function(pageSource, env) { return (function() {
+  var direct = scanComponentsFromSource(pageSource);
+  var allNeeded = [];
+  { var _c = direct; for (var _i = 0; _i < _c.length; _i++) { var name = _c[_i]; if (isSxTruthy(!isSxTruthy(contains(allNeeded, name)))) {
+  allNeeded.push(name);
+}
+(function() {
+  var val = envGet(env, name);
+  return (function() {
+  var deps = (isSxTruthy((isSxTruthy((typeOf(val) == "component")) && !isSxTruthy(isEmpty(componentDeps(val))))) ? componentDeps(val) : transitiveDeps(name, env));
+  return forEach(function(dep) { return (isSxTruthy(!isSxTruthy(contains(allNeeded, dep))) ? append_b(allNeeded, dep) : NIL); }, deps);
+})();
+})(); } }
+  return allNeeded;
+})(); };
+
+  // page-component-bundle
+  var pageComponentBundle = function(pageSource, env) { return componentsNeeded(pageSource, env); };
+
+  // page-css-classes
+  var pageCssClasses = function(pageSource, env) { return (function() {
+  var needed = componentsNeeded(pageSource, env);
+  var classes = [];
+  { var _c = needed; for (var _i = 0; _i < _c.length; _i++) { var name = _c[_i]; (function() {
+  var val = envGet(env, name);
+  return (isSxTruthy((typeOf(val) == "component")) ? forEach(function(cls) { return (isSxTruthy(!isSxTruthy(contains(classes, cls))) ? append_b(classes, cls) : NIL); }, componentCssClasses(val)) : NIL);
+})(); } }
+  { var _c = scanCssClasses(pageSource); for (var _i = 0; _i < _c.length; _i++) { var cls = _c[_i]; if (isSxTruthy(!isSxTruthy(contains(classes, cls)))) {
+  classes.push(cls);
+} } }
+  return classes;
+})(); };
+
+  // scan-io-refs-walk
+  var scanIoRefsWalk = function(node, ioNames, refs) { return (isSxTruthy((typeOf(node) == "symbol")) ? (function() {
+  var name = symbolName(node);
+  return (isSxTruthy(contains(ioNames, name)) ? (isSxTruthy(!isSxTruthy(contains(refs, name))) ? append_b(refs, name) : NIL) : NIL);
+})() : (isSxTruthy((typeOf(node) == "list")) ? forEach(function(item) { return scanIoRefsWalk(item, ioNames, refs); }, node) : (isSxTruthy((typeOf(node) == "dict")) ? forEach(function(key) { return scanIoRefsWalk(dictGet(node, key), ioNames, refs); }, keys(node)) : NIL))); };
+
+  // scan-io-refs
+  var scanIoRefs = function(node, ioNames) { return (function() {
+  var refs = [];
+  scanIoRefsWalk(node, ioNames, refs);
+  return refs;
+})(); };
+
+  // transitive-io-refs-walk
+  var transitiveIoRefsWalk = function(n, seen, allRefs, env, ioNames) { return (isSxTruthy(!isSxTruthy(contains(seen, n))) ? (append_b(seen, n), (function() {
+  var val = envGet(env, n);
+  return (isSxTruthy((typeOf(val) == "component")) ? (forEach(function(ref) { return (isSxTruthy(!isSxTruthy(contains(allRefs, ref))) ? append_b(allRefs, ref) : NIL); }, scanIoRefs(componentBody(val), ioNames)), forEach(function(dep) { return transitiveIoRefsWalk(dep, seen, allRefs, env, ioNames); }, scanRefs(componentBody(val)))) : (isSxTruthy((typeOf(val) == "macro")) ? (forEach(function(ref) { return (isSxTruthy(!isSxTruthy(contains(allRefs, ref))) ? append_b(allRefs, ref) : NIL); }, scanIoRefs(macroBody(val), ioNames)), forEach(function(dep) { return transitiveIoRefsWalk(dep, seen, allRefs, env, ioNames); }, scanRefs(macroBody(val)))) : NIL));
+})()) : NIL); };
+
+  // transitive-io-refs
+  var transitiveIoRefs = function(name, env, ioNames) { return (function() {
+  var allRefs = [];
+  var seen = [];
+  var key = (isSxTruthy(startsWith(name, "~")) ? name : (String("~") + String(name)));
+  transitiveIoRefsWalk(key, seen, allRefs, env, ioNames);
+  return allRefs;
+})(); };
+
+  // compute-all-io-refs
+  var computeAllIoRefs = function(env, ioNames) { return forEach(function(name) { return (function() {
+  var val = envGet(env, name);
+  return (isSxTruthy((typeOf(val) == "component")) ? componentSetIoRefs(val, transitiveIoRefs(name, env, ioNames)) : NIL);
+})(); }, envComponents(env)); };
+
+  // component-pure?
+  var componentPure_p = function(name, env, ioNames) { return isEmpty(transitiveIoRefs(name, env, ioNames)); };
+
+  // render-target
+  var renderTarget = function(name, env, ioNames) { return (function() {
+  var key = (isSxTruthy(startsWith(name, "~")) ? name : (String("~") + String(name)));
+  return (function() {
+  var val = envGet(env, key);
+  return (isSxTruthy(!isSxTruthy((typeOf(val) == "component"))) ? "server" : (function() {
+  var affinity = componentAffinity(val);
+  return (isSxTruthy((affinity == "server")) ? "server" : (isSxTruthy((affinity == "client")) ? "client" : (isSxTruthy(!isSxTruthy(componentPure_p(name, env, ioNames))) ? "server" : "client")));
+})());
+})();
+})(); };
+
+  // page-render-plan
+  var pageRenderPlan = function(pageSource, env, ioNames) { return (function() {
+  var needed = componentsNeeded(pageSource, env);
+  var compTargets = {};
+  var serverList = [];
+  var clientList = [];
+  var ioDeps = [];
+  { var _c = needed; for (var _i = 0; _i < _c.length; _i++) { var name = _c[_i]; (function() {
+  var target = renderTarget(name, env, ioNames);
+  compTargets[name] = target;
+  return (isSxTruthy((target == "server")) ? (append_b(serverList, name), forEach(function(ioRef) { return (isSxTruthy(!isSxTruthy(contains(ioDeps, ioRef))) ? append_b(ioDeps, ioRef) : NIL); }, transitiveIoRefs(name, env, ioNames))) : append_b(clientList, name));
+})(); } }
+  return {"components": compTargets, "server": serverList, "client": clientList, "io-deps": ioDeps};
+})(); };
 
 
   // === Transpiled from router (client-side route matching) ===
@@ -2702,6 +3055,40 @@ return (isSxTruthy((_batchDepth == 0)) ? (function() {
   // register-in-scope
   var registerInScope = function(disposable) { return (isSxTruthy(_islandScope) ? _islandScope(disposable) : NIL); };
 
+  // *store-registry*
+  var _storeRegistry = {};
+
+  // def-store
+  var defStore = function(name, initFn) { return (function() {
+  var registry = _storeRegistry;
+  if (isSxTruthy(!isSxTruthy(hasKey_p(registry, name)))) {
+  _storeRegistry = assoc(registry, name, initFn());
+}
+  return get(_storeRegistry, name);
+})(); };
+
+  // use-store
+  var useStore = function(name) { return (isSxTruthy(hasKey_p(_storeRegistry, name)) ? get(_storeRegistry, name) : error((String("Store not found: ") + String(name) + String(". Call (def-store ...) before (use-store ...).")))); };
+
+  // clear-stores
+  var clearStores = function() { return (_storeRegistry = {}); };
+
+  // emit-event
+  var emitEvent = function(el, eventName, detail) { return domDispatch(el, eventName, detail); };
+
+  // on-event
+  var onEvent = function(el, eventName, handler) { return domListen(el, eventName, handler); };
+
+  // bridge-event
+  var bridgeEvent = function(el, eventName, targetSignal, transformFn) { return effect(function() { return (function() {
+  var remove = domListen(el, eventName, function(e) { return (function() {
+  var detail = eventDetail(e);
+  var newVal = (isSxTruthy(transformFn) ? transformFn(detail) : detail);
+  return reset_b(targetSignal, newVal);
+})(); });
+  return remove;
+})(); }); };
+
 
   // =========================================================================
   // Platform interface — DOM adapter (browser-only)
@@ -2852,6 +3239,16 @@ return (isSxTruthy((_batchDepth == 0)) ? (function() {
     return el.dispatchEvent(evt);
   }
 
+  function domListen(el, name, handler) {
+    if (!_hasDom || !el) return function() {};
+    el.addEventListener(name, handler);
+    return function() { el.removeEventListener(name, handler); };
+  }
+
+  function eventDetail(e) {
+    return (e && e.detail != null) ? e.detail : nil;
+  }
+
   function domQuery(sel) {
     return _hasDom ? document.querySelector(sel) : null;
   }
@@ -2879,6 +3276,12 @@ return (isSxTruthy((_batchDepth == 0)) ? (function() {
   function domSetData(el, key, val) {
     if (el) { if (!el._sxData) el._sxData = {}; el._sxData[key] = val; }
   }
+  function domGetData(el, key) {
+    return (el && el._sxData) ? (el._sxData[key] != null ? el._sxData[key] : nil) : nil;
+  }
+  function jsonParse(s) {
+    try { return JSON.parse(s); } catch(e) { return {}; }
+  }
 
   // =========================================================================
   // Performance overrides — replace transpiled spec with imperative JS
@@ -4706,7 +5109,20 @@ return (isSxTruthy((_batchDepth == 0)) ? (function() {
     renderComponent: typeof sxRenderComponent === "function" ? sxRenderComponent : null,
     getEnv: function() { return componentEnv; },
     resolveSuspense: typeof resolveSuspense === "function" ? resolveSuspense : null,
+    hydrateIslands: typeof sxHydrateIslands === "function" ? sxHydrateIslands : null,
+    disposeIsland: typeof disposeIsland === "function" ? disposeIsland : null,
     init: typeof bootInit === "function" ? bootInit : null,
+    scanRefs: scanRefs,
+    scanComponentsFromSource: scanComponentsFromSource,
+    transitiveDeps: transitiveDeps,
+    computeAllDeps: computeAllDeps,
+    componentsNeeded: componentsNeeded,
+    pageComponentBundle: pageComponentBundle,
+    pageCssClasses: pageCssClasses,
+    scanIoRefs: scanIoRefs,
+    transitiveIoRefs: transitiveIoRefs,
+    computeAllIoRefs: computeAllIoRefs,
+    componentPure_p: componentPure_p,
     splitPathSegments: splitPathSegments,
     parseRoutePattern: parseRoutePattern,
     matchRoute: matchRoute,
@@ -4724,6 +5140,12 @@ return (isSxTruthy((_batchDepth == 0)) ? (function() {
     batch: batch,
     isSignal: isSignal,
     makeSignal: makeSignal,
+    defStore: defStore,
+    useStore: useStore,
+    clearStores: clearStores,
+    emitEvent: emitEvent,
+    onEvent: onEvent,
+    bridgeEvent: bridgeEvent,
     _version: "ref-2.0 (boot+dom+engine+html+orchestration+parser+sx, bootstrap-compiled)"
   };
 
@@ -4766,4 +5188,4 @@ return (isSxTruthy((_batchDepth == 0)) ? (function() {
   if (typeof module !== "undefined" && module.exports) module.exports = Sx;
   else global.Sx = Sx;
 
-})(typeof globalThis !== "undefined" ? globalThis : typeof window !== "undefined" ? window : this);
+})(typeof globalThis !== "undefined" ? globalThis : typeof window !== "undefined" ? window : this);

shared/sx/ref/boot.sx

@@ -84,9 +84,10 @@
           (dom-append el node)
           ;; Hoist head elements from rendered content
           (hoist-head-elements-full el)
-          ;; Process sx- attributes and hydrate
+          ;; Process sx- attributes, hydrate data-sx and islands
           (process-elements el)
-          (sx-hydrate-elements el))))))
+          (sx-hydrate-elements el)
+          (sx-hydrate-islands el))))))
 
 
 ;; --------------------------------------------------------------------------
@@ -117,6 +118,7 @@
               exprs)
             (process-elements el)
             (sx-hydrate-elements el)
+            (sx-hydrate-islands el)
             (dom-dispatch el "sx:resolved" {:id id})))
         (log-warn (str "resolveSuspense: no element for id=" id))))))
 
@@ -305,6 +307,88 @@
       (log-info (str "pages: " (len _page-routes) " routes loaded")))))
 
 
+;; --------------------------------------------------------------------------
+;; Island hydration — activate reactive islands from SSR output
+;; --------------------------------------------------------------------------
+;;
+;; The server renders islands as:
+;;   <div data-sx-island="counter" data-sx-state='{"initial": 0}'>
+;;     ...static HTML...
+;;   </div>
+;;
+;; Hydration:
+;; 1. Find all [data-sx-island] elements
+;; 2. Look up the island component by name
+;; 3. Parse data-sx-state into kwargs
+;; 4. Re-render the island body in a reactive context
+;; 5. Morph existing DOM to preserve structure, focus, scroll
+;; 6. Store disposers on the element for cleanup
+
+(define sx-hydrate-islands
+  (fn (root)
+    (let ((els (dom-query-all (or root (dom-body)) "[data-sx-island]")))
+      (for-each
+        (fn (el)
+          (when (not (is-processed? el "island-hydrated"))
+            (mark-processed! el "island-hydrated")
+            (hydrate-island el)))
+        els))))
+
+(define hydrate-island
+  (fn (el)
+    (let ((name (dom-get-attr el "data-sx-island"))
+          (state-json (or (dom-get-attr el "data-sx-state") "{}")))
+      (let ((comp-name (str "~" name))
+            (env (get-render-env nil)))
+        (let ((comp (env-get env comp-name)))
+          (if (not (or (component? comp) (island? comp)))
+            (log-warn (str "hydrate-island: unknown island " comp-name))
+
+            ;; Parse state and build keyword args
+            (let ((kwargs (json-parse state-json))
+                  (disposers (list))
+                  (local (env-merge (component-closure comp) env)))
+
+              ;; Bind params from kwargs
+              (for-each
+                (fn (p)
+                  (env-set! local p (if (dict-has? kwargs p) (dict-get kwargs p) nil)))
+                (component-params comp))
+
+              ;; Render the island body in a reactive scope
+              (let ((body-dom
+                      (with-island-scope
+                        (fn (disposable) (append! disposers disposable))
+                        (fn () (render-to-dom (component-body comp) local nil)))))
+
+                ;; Morph existing DOM against reactive output
+                (morph-children el body-dom)
+
+                ;; Store disposers for cleanup
+                (dom-set-data el "sx-disposers" disposers)
+
+                ;; Process any sx- attributes on new content
+                (process-elements el)
+
+                (log-info (str "hydrated island: " comp-name
+                               " (" (len disposers) " disposers)"))))))))))
+
+
+;; --------------------------------------------------------------------------
+;; Island disposal — clean up when island removed from DOM
+;; --------------------------------------------------------------------------
+
+(define dispose-island
+  (fn (el)
+    (let ((disposers (dom-get-data el "sx-disposers")))
+      (when disposers
+        (for-each
+          (fn (d)
+            (when (callable? d) (d)))
+          disposers)
+        (dom-set-data el "sx-disposers" nil)))))
+
+
 ;; --------------------------------------------------------------------------
 ;; Full boot sequence
 ;; --------------------------------------------------------------------------
@@ -317,13 +401,15 @@
     ;; 3. Process scripts (components + mounts)
     ;; 4. Process page registry (client-side routing)
     ;; 5. Hydrate [data-sx] elements
-    ;; 6. Process engine elements
+    ;; 6. Hydrate [data-sx-island] elements (reactive islands)
+    ;; 7. Process engine elements
     (do
       (log-info (str "sx-browser " SX_VERSION))
       (init-css-tracking)
       (process-page-scripts)
       (process-sx-scripts nil)
       (sx-hydrate-elements nil)
+      (sx-hydrate-islands nil)
       (process-elements nil))))
 
 
@@ -382,8 +468,25 @@
 ;;   (log-info msg)                → void (console.log with prefix)
 ;;   (log-parse-error label text err) → void (diagnostic parse error)
 ;;
-;; === JSON parsing ===
+;; === JSON ===
+;;   (json-parse str)              → dict/list/value (JSON.parse)
+;;
 ;; === Processing markers ===
 ;;   (mark-processed! el key)      → void
 ;;   (is-processed? el key)        → boolean
+;;
+;; === Morph ===
+;;   (morph-children target source) → void (morph target's children to match source)
+;;
+;; === Island support (from adapter-dom.sx / signals.sx) ===
+;;   (island? x)                   → boolean
+;;   (component-closure comp)      → env
+;;   (component-params comp)       → list of param names
+;;   (component-body comp)         → AST
+;;   (component-name comp)         → string
+;;   (component-has-children? comp) → boolean
+;;   (with-island-scope scope-fn body-fn) → result (track disposables)
+;;   (render-to-dom expr env ns)   → DOM node
+;;   (dom-get-data el key)         → any (from el._sxData)
+;;   (dom-set-data el key val)     → void
 ;; --------------------------------------------------------------------------

shared/sx/ref/bootstrap_js.py

@@ -165,6 +165,13 @@ class JSEmitter:
             "*batch-depth*": "_batchDepth",
             "*batch-queue*": "_batchQueue",
             "*island-scope*": "_islandScope",
+            "*store-registry*": "_storeRegistry",
+            "def-store": "defStore",
+            "use-store": "useStore",
+            "clear-stores": "clearStores",
+            "emit-event": "emitEvent",
+            "on-event": "onEvent",
+            "bridge-event": "bridgeEvent",
             "macro?": "isMacro",
             "primitive?": "isPrimitive",
             "get-primitive": "getPrimitive",
@@ -314,6 +321,8 @@ class JSEmitter:
             "dom-add-class": "domAddClass",
             "dom-remove-class": "domRemoveClass",
             "dom-dispatch": "domDispatch",
+            "dom-listen": "domListen",
+            "event-detail": "eventDetail",
             "dom-query": "domQuery",
             "dom-query-all": "domQueryAll",
             "dom-tag-name": "domTagName",
@@ -322,6 +331,8 @@ class JSEmitter:
             "dom-child-nodes": "domChildNodes",
             "dom-remove-children-after": "domRemoveChildrenAfter",
             "dom-set-data": "domSetData",
+            "dom-get-data": "domGetData",
+            "json-parse": "jsonParse",
             "dict-has?": "dictHas",
             "dict-delete!": "dictDelete",
             "process-bindings": "processBindings",
@@ -508,6 +519,9 @@ class JSEmitter:
             "process-component-script": "processComponentScript",
             "SX_VERSION": "SX_VERSION",
             "boot-init": "bootInit",
+            "sx-hydrate-islands": "sxHydrateIslands",
+            "hydrate-island": "hydrateIsland",
+            "dispose-island": "disposeIsland",
             "resolve-suspense": "resolveSuspense",
             "resolve-mount-target": "resolveMountTarget",
             "sx-render-with-env": "sxRenderWithEnv",
@@ -2870,6 +2884,16 @@ PLATFORM_DOM_JS = """
     return el.dispatchEvent(evt);
   }
 
+  function domListen(el, name, handler) {
+    if (!_hasDom || !el) return function() {};
+    el.addEventListener(name, handler);
+    return function() { el.removeEventListener(name, handler); };
+  }
+
+  function eventDetail(e) {
+    return (e && e.detail != null) ? e.detail : nil;
+  }
+
   function domQuery(sel) {
     return _hasDom ? document.querySelector(sel) : null;
   }
@@ -2897,6 +2921,12 @@ PLATFORM_DOM_JS = """
   function domSetData(el, key, val) {
     if (el) { if (!el._sxData) el._sxData = {}; el._sxData[key] = val; }
   }
+  function domGetData(el, key) {
+    return (el && el._sxData) ? (el._sxData[key] != null ? el._sxData[key] : nil) : nil;
+  }
+  function jsonParse(s) {
+    try { return JSON.parse(s); } catch(e) { return {}; }
+  }
 
   // =========================================================================
   // Performance overrides — replace transpiled spec with imperative JS
@@ -4142,6 +4172,8 @@ def public_api_js(has_html, has_sx, has_dom, has_engine, has_orch, has_boot, has
         api_lines.append('    renderComponent: typeof sxRenderComponent === "function" ? sxRenderComponent : null,')
         api_lines.append('    getEnv: function() { return componentEnv; },')
         api_lines.append('    resolveSuspense: typeof resolveSuspense === "function" ? resolveSuspense : null,')
+        api_lines.append('    hydrateIslands: typeof sxHydrateIslands === "function" ? sxHydrateIslands : null,')
+        api_lines.append('    disposeIsland: typeof disposeIsland === "function" ? disposeIsland : null,')
         api_lines.append('    init: typeof bootInit === "function" ? bootInit : null,')
     elif has_orch:
         api_lines.append('    init: typeof engineInit === "function" ? engineInit : null,')
@@ -4178,6 +4210,12 @@ def public_api_js(has_html, has_sx, has_dom, has_engine, has_orch, has_boot, has
         api_lines.append('    batch: batch,')
         api_lines.append('    isSignal: isSignal,')
         api_lines.append('    makeSignal: makeSignal,')
+        api_lines.append('    defStore: defStore,')
+        api_lines.append('    useStore: useStore,')
+        api_lines.append('    clearStores: clearStores,')
+        api_lines.append('    emitEvent: emitEvent,')
+        api_lines.append('    onEvent: onEvent,')
+        api_lines.append('    bridgeEvent: bridgeEvent,')
     api_lines.append(f'    _version: "{version}"')
     api_lines.append('  };')
     api_lines.append('')

shared/sx/ref/bootstrap_py.py

@@ -174,6 +174,16 @@ class PyEmitter:
             "*batch-depth*": "_batch_depth",
             "*batch-queue*": "_batch_queue",
             "*island-scope*": "_island_scope",
+            "*store-registry*": "_store_registry",
+            "def-store": "def_store",
+            "use-store": "use_store",
+            "clear-stores": "clear_stores",
+            "emit-event": "emit_event",
+            "on-event": "on_event",
+            "bridge-event": "bridge_event",
+            "dom-listen": "dom_listen",
+            "dom-dispatch": "dom_dispatch",
+            "event-detail": "event_detail",
             "macro?": "is_macro",
             "primitive?": "is_primitive",
             "get-primitive": "get_primitive",
@@ -1544,6 +1554,17 @@ def is_empty_dict(d):
     return len(d) == 0
 
 
+# DOM event primitives — no-ops on server (browser-only).
+def dom_listen(el, name, handler):
+    return lambda: None
+
+def dom_dispatch(el, name, detail=None):
+    return False
+
+def event_detail(e):
+    return None
+
+
 def env_has(env, name):
     return name in env
 

shared/sx/ref/signals.sx

@@ -307,13 +307,13 @@
   (fn (name init-fn)
     (let ((registry *store-registry*))
       ;; Only create the store once — subsequent calls return existing
-      (when (not (has? registry name))
+      (when (not (has-key? registry name))
         (set! *store-registry* (assoc registry name (init-fn))))
       (get *store-registry* name))))
 
 (define use-store
   (fn (name)
-    (if (has? *store-registry* name)
+    (if (has-key? *store-registry* name)
       (get *store-registry* name)
       (error (str "Store not found: " name
                   ". Call (def-store ...) before (use-store ...).")))))

shared/sx/ref/sx_ref.py

@@ -416,6 +416,17 @@ def is_empty_dict(d):
     return len(d) == 0
 
 
+# DOM event primitives — no-ops on server (browser-only).
+def dom_listen(el, name, handler):
+    return lambda: None
+
+def dom_dispatch(el, name, detail=None):
+    return False
+
+def event_detail(e):
+    return None
+
+
 def env_has(env, name):
     return name in env
 
@@ -1346,24 +1357,6 @@ render_html_island = lambda island, args, env: (lambda kwargs: (lambda children:
 serialize_island_state = lambda kwargs: (NIL if sx_truthy(is_empty_dict(kwargs)) else json_serialize(kwargs))
 
 
-# === Transpiled from adapter-sx ===
-
-# render-to-sx
-render_to_sx = lambda expr, env: (lambda result: (result if sx_truthy((type_of(result) == 'string')) else serialize(result)))(aser(expr, env))
-
-# aser
-aser = lambda expr, env: _sx_case(type_of(expr), [('number', lambda: expr), ('string', lambda: expr), ('boolean', lambda: expr), ('nil', lambda: NIL), ('symbol', lambda: (lambda name: (env_get(env, name) if sx_truthy(env_has(env, name)) else (get_primitive(name) if sx_truthy(is_primitive(name)) else (True if sx_truthy((name == 'true')) else (False if sx_truthy((name == 'false')) else (NIL if sx_truthy((name == 'nil')) else error(sx_str('Undefined symbol: ', name))))))))(symbol_name(expr))), ('keyword', lambda: keyword_name(expr)), ('list', lambda: ([] if sx_truthy(empty_p(expr)) else aser_list(expr, env))), (None, lambda: expr)])
-
-# aser-list
-aser_list = lambda expr, env: (lambda head: (lambda args: (map(lambda x: aser(x, env), expr) if sx_truthy((not sx_truthy((type_of(head) == 'symbol')))) else (lambda name: (aser_fragment(args, env) if sx_truthy((name == '<>')) else (aser_call(name, args, env) if sx_truthy(starts_with_p(name, '~')) else (aser_call(name, args, env) if sx_truthy(contains_p(HTML_TAGS, name)) else (aser_special(name, expr, env) if sx_truthy((is_special_form(name) if sx_truthy(is_special_form(name)) else is_ho_form(name))) else (aser(expand_macro(env_get(env, name), args, env), env) if sx_truthy((env_has(env, name) if not sx_truthy(env_has(env, name)) else is_macro(env_get(env, name)))) else (lambda f: (lambda evaled_args: (apply(f, evaled_args) if sx_truthy((is_callable(f) if not sx_truthy(is_callable(f)) else ((not sx_truthy(is_lambda(f))) if not sx_truthy((not sx_truthy(is_lambda(f)))) else ((not sx_truthy(is_component(f))) if not sx_truthy((not sx_truthy(is_component(f)))) else (not sx_truthy(is_island(f))))))) else (trampoline(call_lambda(f, evaled_args, env)) if sx_truthy(is_lambda(f)) else (aser_call(sx_str('~', component_name(f)), args, env) if sx_truthy(is_component(f)) else (aser_call(sx_str('~', component_name(f)), args, env) if sx_truthy(is_island(f)) else error(sx_str('Not callable: ', inspect(f))))))))(map(lambda a: trampoline(eval_expr(a, env)), args)))(trampoline(eval_expr(head, env)))))))))(symbol_name(head))))(rest(expr)))(first(expr))
-
-# aser-fragment
-aser_fragment = lambda children, env: (lambda parts: ('' if sx_truthy(empty_p(parts)) else sx_str('(<> ', join(' ', map(serialize, parts)), ')')))(filter(lambda x: (not sx_truthy(is_nil(x))), map(lambda c: aser(c, env), children)))
-
-# aser-call
-aser_call = lambda name, args, env: (lambda parts: _sx_begin(reduce(lambda state, arg: (lambda skip: (assoc(state, 'skip', False, 'i', (get(state, 'i') + 1)) if sx_truthy(skip) else ((lambda val: _sx_begin((_sx_begin(_sx_append(parts, sx_str(':', keyword_name(arg))), _sx_append(parts, serialize(val))) if sx_truthy((not sx_truthy(is_nil(val)))) else NIL), assoc(state, 'skip', True, 'i', (get(state, 'i') + 1))))(aser(nth(args, (get(state, 'i') + 1)), env)) if sx_truthy(((type_of(arg) == 'keyword') if not sx_truthy((type_of(arg) == 'keyword')) else ((get(state, 'i') + 1) < len(args)))) else (lambda val: _sx_begin((_sx_append(parts, serialize(val)) if sx_truthy((not sx_truthy(is_nil(val)))) else NIL), assoc(state, 'i', (get(state, 'i') + 1))))(aser(arg, env)))))(get(state, 'skip')), {'i': 0, 'skip': False}, args), sx_str('(', join(' ', parts), ')')))([name])
-
-
 # === Transpiled from deps (component dependency analysis) ===
 
 # scan-refs
@@ -1493,6 +1486,32 @@ def with_island_scope(scope_fn, body_fn):
 # register-in-scope
 register_in_scope = lambda disposable: (_island_scope(disposable) if sx_truthy(_island_scope) else NIL)
 
+# *store-registry*
+_store_registry = {}
+
+# def-store
+def def_store(name, init_fn):
+    registry = _store_registry
+    if sx_truthy((not sx_truthy(has_key_p(registry, name)))):
+        _store_registry = assoc(registry, name, init_fn())
+    return get(_store_registry, name)
+
+# use-store
+use_store = lambda name: (get(_store_registry, name) if sx_truthy(has_key_p(_store_registry, name)) else error(sx_str('Store not found: ', name, '. Call (def-store ...) before (use-store ...).')))
+
+# clear-stores
+def clear_stores():
+    return _sx_cell_set(_cells, '_store_registry', {})
+
+# emit-event
+emit_event = lambda el, event_name, detail: dom_dispatch(el, event_name, detail)
+
+# on-event
+on_event = lambda el, event_name, handler: dom_listen(el, event_name, handler)
+
+# bridge-event
+bridge_event = lambda el, event_name, target_signal, transform_fn: effect(lambda : (lambda remove: remove)(dom_listen(el, event_name, lambda e: (lambda detail: (lambda new_val: reset_b(target_signal, new_val))((transform_fn(detail) if sx_truthy(transform_fn) else detail)))(event_detail(e)))))
+
 
 # =========================================================================
 # Fixups -- wire up render adapter dispatch
@@ -1530,9 +1549,6 @@ def _wrap_aser_outputs():
 # Public API
 # =========================================================================
 
-# Wrap aser outputs to return SxExpr
-_wrap_aser_outputs()
-
 # Set HTML as default adapter
 _setup_html_adapter()
 

sx/sx/reactive-islands.sx

@@ -111,8 +111,8 @@
               (td :class "px-3 py-2 font-mono text-xs text-stone-500" "signals.sx: emit-event, on-event, bridge-event"))
             (tr :class "border-b border-stone-100"
               (td :class "px-3 py-2 text-stone-700" "Client hydration")
-              (td :class "px-3 py-2 text-amber-600 font-medium" "TODO")
-              (td :class "px-3 py-2 font-mono text-xs text-stone-500" "boot.sx"))
+              (td :class "px-3 py-2 text-green-700 font-medium" "Spec'd")
+              (td :class "px-3 py-2 font-mono text-xs text-stone-500" "boot.sx: sx-hydrate-islands, hydrate-island, dispose-island"))
             (tr :class "border-b border-stone-100"
               (td :class "px-3 py-2 text-stone-700" "Event bindings")
               (td :class "px-3 py-2 text-amber-600 font-medium" "TODO")