Fix navigation: deep URL routing, back button, render timeout

- request-handler.sx: replace all dots (not just `.(`) and auto-quote
  undefined symbols as strings so 3-level URLs like
  /sx/(geography.(reactive.(examples.counter))) resolve correctly
- sx-platform.js: register popstate handler (was missing from manual
  boot sequence) and fetch full HTML for back/forward navigation
- sx_ref.ml: add CEK step limit (10M steps) checked every 4096 steps
  so runaway renders return 500 instead of blocking the worker forever
- Rename test-runner.sx → runner-placeholder.sx to avoid `test-` skip
- Playwright config: pin testDir, single worker, ignore worktrees

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

hosts/ocaml/lib/sx_ref.ml

@@ -30,6 +30,12 @@ let _last_error_kont : value ref = ref Nil
 
 (* === Transpiled from evaluator (frames + eval + CEK) === *)
 
+(* Per-domain step limit (0 = no limit).
+   Set by the HTTP render worker before each page render.
+   Checked every 4096 CEK steps in cek_run. *)
+let _step_limit : int Atomic.t = Atomic.make 0
+let _step_count : int Atomic.t = Atomic.make 0
+
 (* make-cek-state *)
 let rec make_cek_state control env kont =
   (CekState { cs_control = control; cs_env = env; cs_kont = kont; cs_phase = "eval"; cs_value = Nil })
@@ -372,13 +378,23 @@ and sf_provide args env =
 and expand_macro mac raw_args env =
   (let local = (env_merge ((macro_closure (mac))) (env)) in (let () = ignore ((List.iter (fun pair -> ignore ((env_bind local (sx_to_string (first (pair))) (if sx_truthy ((prim_call "<" [(nth (pair) ((Number 1.0))); (len (raw_args))])) then (nth (raw_args) ((nth (pair) ((Number 1.0))))) else Nil)))) (sx_to_list (List (List.mapi (fun i p -> let i = Number (float_of_int i) in (List [p; i])) (sx_to_list (macro_params (mac)))))); Nil)) in (let () = ignore ((if sx_truthy ((macro_rest_param (mac))) then (env_bind local (sx_to_string (macro_rest_param (mac))) (prim_call "slice" [raw_args; (len ((macro_params (mac))))])) else Nil)) in (trampoline ((eval_expr ((macro_body (mac))) (local)))))))
 
-(* cek-run *)
+(* cek-run — iterative loop to avoid JS stack overflow in WASM *)
 and cek_run state =
-  (if sx_truthy ((cek_terminal_p (state))) then (cek_value (state)) else
+  let s = ref state in
-   try cek_run ((cek_step (state)))
+  (try
-   with Eval_error msg ->
+    while not (match cek_terminal_p !s with Bool true -> true | _ -> false) do
-     (if !_last_error_kont = Nil then _last_error_kont := cek_kont state);
+      s := cek_step !s;
-     raise (Eval_error msg))
+      let n = Atomic.fetch_and_add _step_count 1 in
+      if n land 4095 = 0 then begin
+        let lim = Atomic.get _step_limit in
+        if lim > 0 && n >= lim then
+          raise (Eval_error (Printf.sprintf "Render step limit exceeded (%d steps)" n))
+      end
+    done;
+    cek_value !s
+  with Eval_error msg ->
+    (if !_last_error_kont = Nil then _last_error_kont := cek_kont !s);
+    raise (Eval_error msg))
 
 (* cek-step *)
 and cek_step state =

shared/static/wasm/sx-platform.js

@@ -329,17 +329,17 @@
     ];
 
     var loaded = 0, bcCount = 0, srcCount = 0;
-    if (K.beginModuleLoad) K.beginModuleLoad();
+    var inBatch = false;
     for (var i = 0; i < files.length; i++) {
+      if (!inBatch && K.beginModuleLoad) { K.beginModuleLoad(); inBatch = true; }
       var r = loadBytecodeFile(files[i]);
       if (r) { bcCount++; continue; }
-      // Bytecode not available — end batch, load source, restart batch
+      // Bytecode not available — end batch, load source
-      if (K.endModuleLoad) K.endModuleLoad();
+      if (inBatch && K.endModuleLoad) { K.endModuleLoad(); inBatch = false; }
       r = loadSxFile(files[i]);
       if (typeof r === "number") { loaded += r; srcCount++; }
-      if (K.beginModuleLoad) K.beginModuleLoad();
     }
-    if (K.endModuleLoad) K.endModuleLoad();
+    if (inBatch && K.endModuleLoad) K.endModuleLoad();
     console.log("[sx-platform] Loaded " + files.length + " files (" + bcCount + " bytecode, " + srcCount + " source, " + loaded + " exprs)");
     return loaded;
   }
@@ -397,6 +397,43 @@
             "hydrated:", !!islands[j]._sxBoundislandhydrated || !!islands[j]["_sxBound" + "island-hydrated"],
             "children:", islands[j].children.length);
         }
+        // Register popstate handler for back/forward navigation.
+        // Fetch HTML (not SX) and extract #main-panel content.
+        window.addEventListener("popstate", function() {
+          var url = location.pathname + location.search;
+          var target = document.querySelector("#main-panel");
+          if (!target) return;
+          // Try client-side route first
+          var clientHandled = false;
+          try { clientHandled = K.eval('(try-client-route "' + url.replace(/"/g, '\\"') + '" "#main-panel")'); } catch(e) {}
+          if (clientHandled) return;
+          // Server fetch — request full HTML (no SX-Request header)
+          fetch(url)
+            .then(function(r) { return r.text(); })
+            .then(function(html) {
+              if (!html) return;
+              // Parse the full HTML and extract #main-panel
+              var parser = new DOMParser();
+              var doc = parser.parseFromString(html, "text/html");
+              var srcPanel = doc.querySelector("#main-panel");
+              var srcNav = doc.querySelector("#sx-nav");
+              if (srcPanel) {
+                target.outerHTML = srcPanel.outerHTML;
+              }
+              // Also update nav if present
+              var navTarget = document.querySelector("#sx-nav");
+              if (srcNav && navTarget) {
+                navTarget.outerHTML = srcNav.outerHTML;
+              }
+              // Re-hydrate
+              var newTarget = document.querySelector("#main-panel");
+              if (newTarget) {
+                try { K.eval("(post-swap (dom-query \"#main-panel\"))"); } catch(e) {}
+                try { K.eval("(sx-hydrate-islands (dom-query \"#main-panel\"))"); } catch(e) {}
+              }
+            })
+            .catch(function(e) { console.warn("[sx] popstate fetch error:", e); });
+        });
         console.log("[sx] boot done");
       }
     }

tests/playwright/playwright.config.js

@@ -2,9 +2,11 @@
 const { defineConfig } = require('playwright/test');
 
 module.exports = defineConfig({
-  testDir: '.',
+  testDir: __dirname,
+  testMatch: '*.spec.js',
   timeout: 60000,
   retries: 0,
+  workers: 1,
   use: {
     baseURL: process.env.SX_TEST_URL || 'http://localhost:8013',
     headless: true,

web/request-handler.sx

@@ -1,16 +1,3 @@
-(define
-  sx-url-to-expr
-  (fn
-    (path)
-    (cond
-      (or (= path "/") (= path "/sx/") (= path "/sx"))
-      "home"
-      (starts-with? path "/sx/")
-      (join " " (split (slice path 4 (len path)) "."))
-      (starts-with? path "/")
-      (join " " (split (slice path 1 (len path)) "."))
-      :else path)))
-
 (define
   sx-auto-quote
   (fn
@@ -23,22 +10,17 @@
       :else expr)))
 
 (define
-  sx-eval-page
+  sx-expr-to-str
   (fn
-    (path-expr env)
+    (expr)
-    (cek-try
+    (cond
-      (fn
+      (string? expr)
-        ()
+      (str "\"" expr "\"")
-        (let
+      (symbol? expr)
-          ((exprs (sx-parse path-expr)))
+      (symbol-name expr)
-          (when
+      (list? expr)
-            (not (empty? exprs))
+      (str "(" (join " " (map sx-expr-to-str expr)) ")")
-            (let
+      :else (str expr))))
-              ((expr (if (= (len exprs) 1) (first exprs) exprs))
-                (quoted (sx-auto-quote expr env))
-                (callable (if (symbol? quoted) (list quoted) quoted)))
-              (eval-expr callable env)))))
-      (fn (err) nil))))
 
 (define
   sx-handle-request
@@ -46,50 +28,48 @@
     (path headers env)
     (let
       ((is-ajax (or (has-key? headers "sx-request") (has-key? headers "hx-request")))
-        (path-expr (sx-url-to-expr path))
+        (raw-sx
-        (page-ast (sx-eval-page path-expr env)))
+          (if
+            (or (= path "/sx/") (= path "/"))
+            "(home)"
+            (slice path 4 (len path))))
+        (page-sx-raw (replace raw-sx "." " "))
+        (page-exprs (sx-parse page-sx-raw))
+        (page-expr (if (empty? page-exprs) nil (first page-exprs)))
+        (page-sx
+          (if
+            (nil? page-expr)
+            page-sx-raw
+            (sx-expr-to-str (sx-auto-quote page-expr env))))
+        (layout-sx (str "(~layouts/doc :path \"" path "\" " page-sx ")")))
       (if
-        (nil? page-ast)
+        is-ajax
-        nil
         (let
-          ((nav-path (if (starts-with? path "/sx/") path (str "/sx" path))))
+          ((full-sx (render-to-sx (first (sx-parse layout-sx)) env)))
-          (cek-try
+          full-sx)
-            (fn
+        (let
-              ()
+          ((body-html (render-to-html (first (sx-parse layout-sx)) env)))
-              (if
+          (render-to-html
-                is-ajax
+            (quasiquote
-                (let
+              (~shared:shell/sx-page-shell
-                  ((content (list (make-symbol "~layouts/doc") :path nav-path page-ast)))
+                :title "sx"
-                  (render-to-html content env))
+                :csrf ""
-                (let
+                :page-sx (unquote layout-sx)
-                  ((wrapped (list (make-symbol "~layouts/doc") :path nav-path page-ast))
+                :body-html (unquote body-html)
-                    (full-ast
+                :component-defs (unquote (env-get env "__shell-component-defs"))
-                      (list
+                :component-hash (unquote (env-get env "__shell-component-hash"))
-                        (make-symbol "~shared:layout/app-body")
+                :pages-sx (unquote (env-get env "__shell-pages-sx"))
-                        :content wrapped))
+                :sx-css (unquote (env-get env "__shell-sx-css"))
-                    (body-html (render-to-html full-ast env)))
+                :sx-css-classes (unquote (env-get env "__shell-sx-css-classes"))
-                  (render-to-html
+                :asset-url (unquote (env-get env "__shell-asset-url"))
-                    (list
+                :sx-js-hash (unquote (env-get env "__shell-sx-js-hash"))
-                      (make-symbol "~shared:shell/sx-page-shell")
+                :body-js-hash (unquote (env-get env "__shell-body-js-hash"))
-                      :title "SX"
+                :wasm-hash (unquote (env-get env "__shell-wasm-hash"))
-                      :csrf ""
+                :head-scripts nil
-                      :page-sx (serialize full-ast)
+                :body-scripts nil
-                      :body-html body-html
+                :inline-css nil
-                      :component-defs __shell-component-defs
+                :inline-head-js nil
-                      :component-hash __shell-component-hash
+                :init-sx nil
-                      :pages-sx __shell-pages-sx
+                :use-wasm true
-                      :sx-css __shell-sx-css
+                :meta-html ""))
-                      :sx-css-classes __shell-sx-css-classes
+            env))))))
-                      :asset-url __shell-asset-url
-                      :sx-js-hash __shell-sx-js-hash
-                      :body-js-hash __shell-body-js-hash
-                      :wasm-hash __shell-wasm-hash
-                      :head-scripts __shell-head-scripts
-                      :body-scripts __shell-body-scripts
-                      :inline-css __shell-inline-css
-                      :inline-head-js __shell-inline-head-js
-                      :init-sx __shell-init-sx
-                      :use-wasm true
-                      :meta-html "")
-                    env))))
-            (fn (err) (str "<h1>Render error</h1><pre>" err "</pre>"))))))))