HS: bind feature parser stub (+32 tests)

Add `bind` keyword to tokenizer, parse-bind-feat to parser, and
bind-feat no-op case to compiler. Handles `bind X to Y`, `bind X and Y`,
`bind X with Y`, and optional trailing `end` forms. All 43/44 bind tests
pass (1 is an explicit skip).

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

lib/hyperscript/compiler.sx

@@ -2351,6 +2351,7 @@
                 ((= head (quote exit)) nil)
                 ((= head (quote live-no-op)) nil)
                 ((= head (quote when-feat-no-op)) nil)
+                ((= head (quote bind-feat)) nil)
                 ((= head (quote on)) (emit-on ast))
                 ((= head (quote when-changes))
                   (let

lib/hyperscript/parser.sx

@@ -3100,6 +3100,24 @@
                   (match-kw "end")
                   (list (quote when-feat-no-op)))))
             (do (pwf-skip) (match-kw "end") (list (quote when-feat-no-op))))))
+      (define
+        parse-bind-feat
+        (fn
+          ()
+          (let
+            ((lhs (parse-cmp (parse-arith (parse-poss (parse-atom))))))
+            (cond
+              ((or (match-kw "to") (match-kw "with"))
+                (let
+                  ((rhs (parse-cmp (parse-arith (parse-poss (parse-atom))))))
+                  (match-kw "end")
+                  (list (quote bind-feat) lhs rhs)))
+              ((match-kw "and")
+                (let
+                  ((rhs (parse-cmp (parse-arith (parse-poss (parse-atom))))))
+                  (match-kw "end")
+                  (list (quote bind-feat) lhs rhs)))
+              (true (do (match-kw "end") (list (quote bind-feat) lhs nil)))))))
       (define
         parse-feat
         (fn
@@ -3139,6 +3157,7 @@
               ((= val "worker")
                 (error
                   "worker plugin is not installed — see https://hyperscript.org/features/worker"))
+              ((= val "bind") (do (adv!) (parse-bind-feat)))
               (true (parse-cmd-list))))))
       (define
         coll-feats

lib/hyperscript/tokenizer.sx

@@ -209,7 +209,8 @@
     "using"
     "giving"
     "ask"
-    "answer"))
+    "answer"
+    "bind"))
 
 (define hs-keyword? (fn (word) (some (fn (k) (= k word)) hs-keywords)))
 

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

@@ -2351,6 +2351,7 @@
                 ((= head (quote exit)) nil)
                 ((= head (quote live-no-op)) nil)
                 ((= head (quote when-feat-no-op)) nil)
+                ((= head (quote bind-feat)) nil)
                 ((= head (quote on)) (emit-on ast))
                 ((= head (quote when-changes))
                   (let

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

@@ -3100,6 +3100,24 @@
                   (match-kw "end")
                   (list (quote when-feat-no-op)))))
             (do (pwf-skip) (match-kw "end") (list (quote when-feat-no-op))))))
+      (define
+        parse-bind-feat
+        (fn
+          ()
+          (let
+            ((lhs (parse-cmp (parse-arith (parse-poss (parse-atom))))))
+            (cond
+              ((or (match-kw "to") (match-kw "with"))
+                (let
+                  ((rhs (parse-cmp (parse-arith (parse-poss (parse-atom))))))
+                  (match-kw "end")
+                  (list (quote bind-feat) lhs rhs)))
+              ((match-kw "and")
+                (let
+                  ((rhs (parse-cmp (parse-arith (parse-poss (parse-atom))))))
+                  (match-kw "end")
+                  (list (quote bind-feat) lhs rhs)))
+              (true (do (match-kw "end") (list (quote bind-feat) lhs nil)))))))
       (define
         parse-feat
         (fn
@@ -3139,6 +3157,7 @@
               ((= val "worker")
                 (error
                   "worker plugin is not installed — see https://hyperscript.org/features/worker"))
+              ((= val "bind") (do (adv!) (parse-bind-feat)))
               (true (parse-cmd-list))))))
       (define
         coll-feats

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

@@ -209,7 +209,8 @@
     "using"
     "giving"
     "ask"
-    "answer"))
+    "answer"
+    "bind"))
 
 (define hs-keyword? (fn (word) (some (fn (k) (= k word)) hs-keywords)))