SxExpr aser wire format fix + Playwright test infrastructure + blob protocol

Aser serialization: aser-call/fragment now return SxExpr instead of String.
serialize/inspect passes SxExpr through unquoted, preventing the double-
escaping (\" → \\\" ) that broke client-side parsing when aser wire format
was output via raw! into <script> tags. Added make-sx-expr + sx-expr-source
primitives to OCaml and JS hosts.

Binary blob protocol: eval, aser, aser-slot, and sx-page-full now send SX
source as length-prefixed blobs instead of escaped strings. Eliminates pipe
desync from concurrent requests and removes all string-escape round-trips
between Python and OCaml.

Bridge safety: re-entrancy guard (_in_io_handler) raises immediately if an
IO handler tries to call the bridge, preventing silent deadlocks.

Fetch error logging: orchestration.sx error callback now logs method + URL
via log-warn. Platform catches (fetchAndRestore, fetchPreload, bindBoostForm)
also log errors instead of silently swallowing them.

Transpiler fixes: makeEnv, scopePeek, scopeEmit, makeSxExpr added as
platform function definitions + transpiler mappings — were referenced in
transpiled code but never defined as JS functions.

Playwright test infrastructure:
- nav() captures JS errors and fails fast with the actual error message
- Checks for [object Object] rendering artifacts
- New tests: delete-row interaction, full page refresh, back button,
  direct load with fresh context, code block content verification
- Default base URL changed to localhost:8013 (standalone dev server)
- docker-compose.dev-sx.yml: port 8013 exposed for local testing
- test-sx-build.sh: build + unit tests + Playwright smoke tests

Geography content: index page component written (sx/sx/geography/index.sx)
describing OCaml evaluator, wire formats, rendering pipeline, and topic
links. Wiring blocked by aser-expand-component children passing issue.

Tests: 1080/1080 JS, 952/952 OCaml, 66/66 Playwright

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

hosts/javascript/platform.py

@@ -1130,8 +1130,10 @@ PRIMITIVES_JS_MODULES: dict[str, str] = {
   PRIMITIVES["emit!"] = sxEmit;
   PRIMITIVES["emitted"] = sxEmitted;
   // Aliases for aser adapter (avoids CEK special form conflict on server)
-  PRIMITIVES["scope-emit!"] = sxEmit;
-  PRIMITIVES["scope-peek"] = sxEmitted;
+  var scopeEmit = sxEmit;
+  var scopePeek = sxEmitted;
+  PRIMITIVES["scope-emit!"] = scopeEmit;
+  PRIMITIVES["scope-peek"] = scopePeek;
 ''',
 }
 # Modules to include by default (all)
@@ -1170,6 +1172,7 @@ PLATFORM_JS_PRE = '''
     if (x._spread) return "spread";
     if (x._macro) return "macro";
     if (x._raw) return "raw-html";
+    if (x._sx_expr) return "sx-expr";
     if (typeof Node !== "undefined" && x instanceof Node) return "dom-node";
     if (Array.isArray(x)) return "list";
     if (typeof x === "object") return "dict";
@@ -1441,6 +1444,7 @@ PLATFORM_JS_POST = '''
   // escape-html and escape-attr are now library functions defined in render.sx
   function rawHtmlContent(r) { return r.html; }
   function makeRawHtml(s) { return { _raw: true, html: s }; }
+  function makeSxExpr(s) { return { _sx_expr: true, source: s }; }
   function sxExprSource(x) { return x && x.source ? x.source : String(x); }
 
   // Placeholders — overridden by transpiled spec from parser.sx / adapter-sx.sx
@@ -1669,7 +1673,8 @@ CEK_FIXUPS_JS = '''
   PRIMITIVES["island?"] = isIsland;
   PRIMITIVES["make-symbol"] = function(n) { return new Symbol(n); };
   PRIMITIVES["is-html-tag?"] = function(n) { return HTML_TAGS.indexOf(n) >= 0; };
-  PRIMITIVES["make-env"] = function() { return merge(componentEnv, PRIMITIVES); };
+  function makeEnv() { return merge(componentEnv, PRIMITIVES); }
+  PRIMITIVES["make-env"] = makeEnv;
 
   // localStorage — defined here (before boot) so islands can use at hydration
   PRIMITIVES["local-storage-get"] = function(key) {
@@ -1792,7 +1797,7 @@ PLATFORM_PARSER_JS = r"""
   function escapeString(s) {
     return s.replace(/\\/g, "\\\\").replace(/"/g, '\\"').replace(/\n/g, "\\n").replace(/\t/g, "\\t");
   }
-  function sxExprSource(e) { return typeof e === "string" ? e : String(e); }
+  function sxExprSource(e) { return typeof e === "string" ? e : (e && e.source ? e.source : String(e)); }
   var charFromCode = PRIMITIVES["char-from-code"];
 """
 
@@ -2298,7 +2303,10 @@ PLATFORM_ORCHESTRATION_JS = """
           }
         }
       });
-    }).catch(function() { location.reload(); });
+    }).catch(function(err) {
+      logWarn("sx:popstate fetch error " + url + " — " + (err && err.message ? err.message : err));
+      location.reload();
+    });
   }
 
   function fetchStreaming(target, url, headers) {
@@ -2436,7 +2444,9 @@ PLATFORM_ORCHESTRATION_JS = """
       return resp.text().then(function(text) {
         preloadCacheSet(cache, url, text, ct);
       });
-    }).catch(function() { /* ignore */ });
+    }).catch(function(err) {
+      logInfo("sx:preload error " + url + " — " + (err && err.message ? err.message : err));
+    });
   }
 
   // --- Request body building ---
@@ -2725,6 +2735,8 @@ PLATFORM_ORCHESTRATION_JS = """
       var liveAction = form.getAttribute("action") || _action || location.href;
       executeRequest(form, { method: liveMethod, url: liveAction }).then(function() {
         try { history.pushState({ sxUrl: liveAction, scrollY: window.scrollY }, "", liveAction); } catch (err) {}
+      }).catch(function(err) {
+        logWarn("sx:boost form error " + liveMethod + " " + liveAction + " — " + (err && err.message ? err.message : err));
       });
     });
   }

hosts/javascript/run_tests.js

@@ -218,6 +218,19 @@ env["component-has-children"] = function(c) {
   return c && c.has_children ? c.has_children : false;
 };
 
+// Aser test helper: parse SX source, evaluate via aser, return wire format string
+env["render-sx"] = function(source) {
+  const exprs = Sx.parse(source);
+  const parts = [];
+  for (const expr of exprs) {
+    const result = Sx.renderToSx(expr, env);
+    if (result !== null && result !== undefined && result !== Sx.NIL) {
+      parts.push(typeof result === "string" ? result : Sx.serialize(result));
+    }
+  }
+  return parts.join("");
+};
+
 // Platform test functions
 env["try-call"] = function(thunk) {
   try {

hosts/javascript/transpiler.sx

@@ -54,6 +54,8 @@
   "make-action-def" "makeActionDef"
   "make-page-def" "makePageDef"
   "make-symbol" "makeSymbol"
+  "make-env" "makeEnv"
+  "make-sx-expr" "makeSxExpr"
   "make-keyword" "makeKeyword"
   "lambda-params" "lambdaParams"
   "lambda-body" "lambdaBody"
@@ -163,6 +165,7 @@
   "aser-special" "aserSpecial"
   "eval-case-aser" "evalCaseAser"
   "sx-serialize" "sxSerialize"
+
   "sx-serialize-dict" "sxSerializeDict"
   "sx-expr-source" "sxExprSource"
   "sf-if" "sfIf"
@@ -620,6 +623,8 @@
   "cond-scheme?" "condScheme_p"
   "scope-push!" "scopePush"
   "scope-pop!" "scopePop"
+  "scope-emit!" "scopeEmit"
+  "scope-peek" "scopePeek"
   "provide-push!" "providePush"
   "provide-pop!" "providePop"
   "context" "sxContext"