Replace invoke with cek-call in reactive island primitives

All signal operations (computed, effect, batch, etc.) now dispatch
function calls through cek-call, which routes SX lambdas via cek-run
and native callables via apply. This replaces the invoke shim.

Key changes:
- cek.sx: add cek-call (defined before reactive-shift-deref), replace
  invoke in subscriber disposal and ReactiveResetFrame handler
- signals.sx: replace all 11 invoke calls with cek-call
- js.sx: fix octal escape in js-quote-string (char-from-code 0)
- platform_js.py: fix JS append to match Python (list concat semantics),
  add Continuation type guard in PLATFORM_CEK_JS, add scheduleIdle
  safety check, module ordering (cek before signals)
- platform_py.py: fix ident-char regex (remove [ ] from valid chars),
  module ordering (cek before signals)
- run_js_sx.py: emit PLATFORM_CEK_JS before transpiled spec files
- page-functions.sx: add cek and provide page functions for SX URLs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

shared/sx/ref/platform_js.py

@@ -52,7 +52,7 @@ SPEC_MODULES = {
 
 # Explicit ordering for spec modules with dependencies.
 # Modules listed here are emitted in this order; any not listed use alphabetical.
-SPEC_MODULE_ORDER = ["deps", "frames", "page-helpers", "router", "signals", "cek"]
+SPEC_MODULE_ORDER = ["deps", "frames", "page-helpers", "router", "cek", "signals"]
 
 
 EXTENSION_NAMES = {"continuations"}
@@ -1004,7 +1004,7 @@ PRIMITIVES_JS_MODULES: dict[str, str] = {
   PRIMITIVES["rest"] = function(c) { if (c && typeof c.slice !== "function") { console.error("[sx-debug] rest called on non-sliceable:", typeof c, c, new Error().stack); return []; } return c ? c.slice(1) : []; };
   PRIMITIVES["nth"] = function(c, n) { return c && n >= 0 && n < c.length ? c[n] : NIL; };
   PRIMITIVES["cons"] = function(x, c) { return [x].concat(c || []); };
-  PRIMITIVES["append"] = function(c, x) { return (c || []).concat([x]); };
+  PRIMITIVES["append"] = function(c, x) { return (c || []).concat(Array.isArray(x) ? x : [x]); };
   PRIMITIVES["append!"] = function(arr, x) { arr.push(x); return arr; };
   PRIMITIVES["chunk-every"] = function(c, n) {
     var r = []; for (var i = 0; i < c.length; i += n) r.push(c.slice(i, i + n)); return r;
@@ -1487,6 +1487,14 @@ PLATFORM_CEK_JS = '''
   // Platform: CEK module — explicit CEK machine
   // =========================================================================
 
+  // Continuation type (needed by CEK even without the tree-walk shift/reset extension)
+  if (typeof Continuation === "undefined") {
+    function Continuation(fn) { this.fn = fn; }
+    Continuation.prototype._continuation = true;
+    Continuation.prototype.call = function(value) { return this.fn(value !== undefined ? value : NIL); };
+    PRIMITIVES["continuation?"] = function(x) { return x != null && x._continuation === true; };
+  }
+
   // Standalone aliases for primitives used by cek.sx / frames.sx
   var inc = PRIMITIVES["inc"];
   var dec = PRIMITIVES["dec"];
@@ -1608,10 +1616,10 @@ PLATFORM_PARSER_JS = r"""
   // =========================================================================
   // Character classification derived from the grammar:
   //   ident-start → [a-zA-Z_~*+\-><=/!?&]
-  //   ident-char  → ident-start + [0-9.:\/\[\]#,]
+  //   ident-char  → ident-start + [0-9.:\/\#,]
 
   var _identStartRe = /[a-zA-Z_~*+\-><=/!?&]/;
-  var _identCharRe = /[a-zA-Z0-9_~*+\-><=/!?.:&/\[\]#,]/;
+  var _identCharRe = /[a-zA-Z0-9_~*+\-><=/!?.:&/#,]/;
 
   function isIdentStart(ch) { return _identStartRe.test(ch); }
   function isIdentChar(ch) { return _identCharRe.test(ch); }
@@ -2436,6 +2444,10 @@ PLATFORM_ORCHESTRATION_JS = """
   }
   function scheduleIdle(fn) {
     var cb = _wrapSxFn(fn);
+    if (typeof cb !== "function") {
+      console.error("[sx-ref] scheduleIdle: callback not callable, fn type:", typeof fn, "fn:", fn, "_lambda:", fn && fn._lambda);
+      return;
+    }
     if (typeof requestIdleCallback !== "undefined") requestIdleCallback(cb);
     else setTimeout(cb, 0);
   }
@@ -2525,8 +2537,12 @@ PLATFORM_ORCHESTRATION_JS = """
       e.preventDefault();
       // Re-read href from element at click time (not closed-over value)
       var liveHref = el.getAttribute("href") || _href;
+      console.log("[sx-debug] bindBoostLink click:", liveHref, "el:", el.tagName, el.textContent.slice(0,30));
       executeRequest(el, { method: "GET", url: liveHref }).then(function() {
+        console.log("[sx-debug] boost fetch OK, pushState:", liveHref);
         try { history.pushState({ sxUrl: liveHref, scrollY: window.scrollY }, "", liveHref); } catch (err) {}
+      }).catch(function(err) {
+        console.error("[sx-debug] boost fetch ERROR:", err);
       });
     });
   }
@@ -2551,21 +2567,25 @@ PLATFORM_ORCHESTRATION_JS = """
       // Re-read href from element at click time (not closed-over value)
       var liveHref = link.getAttribute("href") || _href;
       var pathname = urlPathname(liveHref);
+      console.log("[sx-debug] bindClientRouteClick:", pathname, "el:", link.tagName, link.textContent.slice(0,30));
       // Find target selector: sx-boost ancestor, explicit sx-target, or #main-panel
       var boostEl = link.closest("[sx-boost]");
       var targetSel = boostEl ? boostEl.getAttribute("sx-boost") : null;
       if (!targetSel || targetSel === "true") {
         targetSel = link.getAttribute("sx-target") || "#main-panel";
       }
+      console.log("[sx-debug] targetSel:", targetSel, "trying client route...");
       if (tryClientRoute(pathname, targetSel)) {
+        console.log("[sx-debug] client route SUCCESS, pushState:", liveHref);
         try { history.pushState({ sxUrl: liveHref, scrollY: window.scrollY }, "", liveHref); } catch (err) {}
         if (typeof window !== "undefined") window.scrollTo(0, 0);
       } else {
-        logInfo("sx:route server " + pathname);
+        console.log("[sx-debug] client route FAILED, server fetch:", liveHref);
         executeRequest(link, { method: "GET", url: liveHref }).then(function() {
+          console.log("[sx-debug] server fetch OK, pushState:", liveHref);
           try { history.pushState({ sxUrl: liveHref, scrollY: window.scrollY }, "", liveHref); } catch (err) {}
         }).catch(function(err) {
-          logWarn("sx:route server fetch error: " + (err && err.message ? err.message : err));
+          console.error("[sx-debug] server fetch ERROR:", err);
         });
       }
     });