HS E36: socket URL parsing + hs-socket-register! runtime (+3 tests)

- parser.sx: parse-socket-feat handles /path and scheme:// URLs; collect-url
  greedily joins URL continuation tokens (ident/number/op/colon/dot)
- tokenizer.sx: fix :// not treated as line comment (lookback check)
- compiler.sx: emit-socket compiles socket AST to hs-socket-register! call
- runtime.sx: hs-socket-register! normalises URL (relative→ws:/wss:),
  constructs WebSocket, builds wrapper dict, binds on window name-path
- hs-run-filtered.js: WebSocket mock uses plain object (not JS array) so
  host-global returns a foreign value rather than SX list; host-get idx works

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

shared/static/wasm/sx/hs-compiler.sx

@@ -787,6 +787,31 @@
               (quote fn)
               (cons (quote me) (map make-symbol params))
               (cons (quote do) (map hs-to-sx body)))))))
+    (define
+      emit-socket
+      (fn
+        (ast)
+        (let
+          ((name-path (nth ast 1))
+           (url (nth ast 2))
+           (timeout-ms (nth ast 3))
+           (on-msg (nth ast 4)))
+         (let
+           ((handler
+             (if
+               (nil? on-msg)
+               nil
+               (let
+                 ((body (hs-to-sx (nth on-msg 2))))
+                 (list (quote fn) (list (quote event)) body))))
+             (json?-val (if (nil? on-msg) false (nth on-msg 1))))
+           (list
+             (quote hs-socket-register!)
+             (cons (quote list) name-path)
+             url
+             (if (nil? timeout-ms) nil (hs-to-sx timeout-ms))
+             handler
+             json?-val)))))
     (fn
       (ast)
       (cond
@@ -2075,6 +2100,7 @@
                           (quote _hs-def-val))
                         (quote _hs-def-val))))))
               ((= head (quote behavior)) (emit-behavior ast))
+              ((= head (quote socket)) (emit-socket ast))
               ((= head (quote sx-eval))
                 (let
                   ((src (nth ast 1)))

shared/static/wasm/sx/hs-parser.sx

@@ -2729,6 +2729,63 @@
                   (match-kw "end")
                   (list (quote when-feat-no-op)))))
             (do (pwf-skip) (match-kw "end") (list (quote when-feat-no-op))))))
+      (define
+        parse-socket-feat
+        (fn
+          ()
+          (let
+            ((seg0 (tp-val)))
+            (adv!)
+            (define
+              collect-segs
+              (fn
+                (acc)
+                (if
+                  (= (tp-type) "class")
+                  (let
+                    ((seg (tp-val)))
+                    (adv!)
+                    (collect-segs (append acc (list seg))))
+                  acc)))
+            (let
+              ((name-path (collect-segs (list seg0))))
+              (define
+                url-cont?
+                (fn
+                  ()
+                  (or
+                    (= (tp-type) "ident")
+                    (= (tp-type) "number")
+                    (= (tp-type) "op")
+                    (= (tp-type) "colon")
+                    (= (tp-type) "dot")
+                    (and
+                      (= (tp-type) "keyword")
+                      (not
+                        (or
+                          (= (tp-val) "end")
+                          (= (tp-val) "with")
+                          (= (tp-val) "on")
+                          (= (tp-val) "as")))))))
+              (define
+                collect-url
+                (fn
+                  (parts)
+                  (if
+                    (and (not (at-end?)) (url-cont?))
+                    (let
+                      ((v (tp-val)))
+                      (adv!)
+                      (collect-url (append parts (list v))))
+                    (join "" parts))))
+              (let
+                ((url (cond ((and (= (tp-type) "op") (= (tp-val) "/")) (do (adv!) (collect-url (list "/")))) ((= (tp-type) "ident") (let ((scheme (tp-val))) (adv!) (if (= (tp-type) "colon") (collect-url (list scheme)) (parse-arith (parse-poss (list (quote ref) scheme)))))) (true (parse-atom)))))
+                (let
+                  ((timeout-ms (if (match-kw "with") (do (adv!) (parse-expr)) nil)))
+                  (let
+                    ((on-msg (if (match-kw "on") (do (adv!) (let ((json? (if (match-kw "as") (do (adv!) true) false))) (let ((body (parse-cmd-list))) (list (quote on-message) json? body)))) nil)))
+                    (match-kw "end")
+                    (list (quote socket) name-path url timeout-ms on-msg))))))))
       (define
         parse-feat
         (fn
@@ -2749,6 +2806,7 @@
               ((= val "behavior") (do (adv!) (parse-behavior-feat)))
               ((= val "live") (do (adv!) (parse-live-feat)))
               ((= val "when") (do (adv!) (parse-when-feat)))
+              ((= val "socket") (do (adv!) (parse-socket-feat)))
               (true (parse-cmd-list))))))
       (define
         coll-feats

shared/static/wasm/sx/hs-runtime.sx

@@ -2525,3 +2525,56 @@
   (fn
     (fn-name args)
     (let ((fn (host-global fn-name))) (if fn (host-call-fn fn args) nil))))
+
+;; ── WebSocket / socket feature ───────────────────────────────────
+
+(define
+  hs-socket-register!
+  (fn
+    (name-path url timeout-ms handler json?)
+    ;; 1. Normalise URL — absolute ws/wss pass through; relative paths get scheme+host
+    (let
+      ((ws-url
+        (cond
+          ((or (starts-with? url "ws://") (starts-with? url "wss://")) url)
+          (true
+            (let
+              ((proto (host-get (host-global "location") "protocol"))
+                (h (host-get (host-global "location") "host")))
+              (str (if (= proto "https:") "wss:" "ws:") "//" h url))))))
+      ;; 2. Construct WebSocket
+      (let
+        ((ws (host-new "WebSocket" ws-url)))
+        ;; 3. Build wrapper dict
+        (let
+          ((wrapper
+            {:raw ws
+             :url ws-url
+             :timeout timeout-ms
+             :pending {}
+             :handler handler
+             :json? json?
+             :closed? false}))
+          ;; 4. Wire RPC proxy via JS factory (if available)
+          (let
+            ((proxy-factory (host-global "_hs_make_rpc_proxy")))
+            (when proxy-factory
+              (host-set! wrapper "rpc"
+                (host-call proxy-factory "call" nil wrapper))))
+          ;; 5. Bind wrapper on window, walking name-path
+          (define
+            bind-path!
+            (fn
+              (obj path)
+              (if
+                (= (len path) 1)
+                (host-set! obj (first path) wrapper)
+                (let
+                  ((key (first path))
+                    (rest-path (rest path)))
+                  (let
+                    ((next (or (host-get obj key) {})))
+                    (host-set! obj key next)
+                    (bind-path! next rest-path))))))
+          (bind-path! (host-global "window") name-path)
+          wrapper)))))

shared/static/wasm/sx/hs-tokenizer.sx

@@ -441,7 +441,11 @@
               (cond
                 (and (= ch "-") (< (+ pos 1) src-len) (= (hs-peek 1) "-"))
                 (do (hs-advance! 2) (skip-comment!) (scan!))
-                (and (= ch "/") (< (+ pos 1) src-len) (= (hs-peek 1) "/"))
+                (and
+                  (= ch "/")
+                  (< (+ pos 1) src-len)
+                  (= (hs-peek 1) "/")
+                  (not (and (> pos 0) (= (hs-peek -1) ":"))))
                 (do (hs-advance! 2) (skip-comment!) (scan!))
                 (and
                   (= ch "<")