From 1723808517bcef0dca2652b5672aacdf37bfec50 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Mon, 27 Apr 2026 05:18:38 +0000
Subject: [PATCH] HS: viewTransition command (+9 tests)

Add 'start view transition [using EXPR] [then] BODY end' syntax.
- tokenizer: add 'view' as a keyword
- parser: add 'start' to cmd-kw? and dispatch to view-transition! AST node
- compiler: emit hs-view-transition! call from view-transition! node

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 lib/hyperscript/compiler.sx           |  3 +++
 lib/hyperscript/parser.sx             | 13 ++++++++++++-
 lib/hyperscript/tokenizer.sx          |  1 +
 shared/static/wasm/sx/hs-compiler.sx  |  3 +++
 shared/static/wasm/sx/hs-parser.sx    | 13 ++++++++++++-
 shared/static/wasm/sx/hs-tokenizer.sx |  1 +
 6 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/lib/hyperscript/compiler.sx b/lib/hyperscript/compiler.sx
index cf5aad15..05504731 100644
--- a/lib/hyperscript/compiler.sx
+++ b/lib/hyperscript/compiler.sx
@@ -1832,6 +1832,9 @@
                     (hs-to-sx (nth ast 2))))
                 ((= head (quote set-el!))
                   (list (quote hs-set-element!) (hs-to-sx (nth ast 1)) (hs-to-sx (nth ast 2))))
+                ((= head (quote view-transition!))
+                  (let ((body (nth ast 2)))
+                    (list (quote hs-view-transition!) (hs-to-sx (nth ast 1)) (if (nil? body) (quote nil) (hs-to-sx body)))))
                 ((= head (quote put!))
                   (let
                     ((val (hs-to-sx (nth ast 1)))
diff --git a/lib/hyperscript/parser.sx b/lib/hyperscript/parser.sx
index dc70ed29..0f631c2b 100644
--- a/lib/hyperscript/parser.sx
+++ b/lib/hyperscript/parser.sx
@@ -2711,6 +2711,16 @@
                 (do (adv!) (list (quote exit))))
               ((and (= typ "keyword") (= val "js"))
                 (do (adv!) (parse-js-block)))
+              ((and (= typ "keyword") (= val "start"))
+                (do
+                  (adv!)
+                  (expect-kw! "view")
+                  (expect-kw! "transition")
+                  (let ((using (if (match-kw "using") (parse-expr) nil)))
+                    (match-kw "then")
+                    (let ((body (parse-cmd-list)))
+                      (match-kw "end")
+                      (list (quote view-transition!) using body)))))
               (true (parse-expr))))))
       (define
         parse-cmd-list
@@ -2767,7 +2777,8 @@
                 (= v "pick")
                 (= v "ask")
                 (= v "answer")
-                (= v "js"))))
+                (= v "js")
+                (= v "start"))))
           (define
             cl-collect
             (fn
diff --git a/lib/hyperscript/tokenizer.sx b/lib/hyperscript/tokenizer.sx
index 8b3a6a80..02255e1a 100644
--- a/lib/hyperscript/tokenizer.sx
+++ b/lib/hyperscript/tokenizer.sx
@@ -131,6 +131,7 @@
     "append"
     "settle"
     "transition"
+    "view"
     "over"
     "closest"
     "next"
diff --git a/shared/static/wasm/sx/hs-compiler.sx b/shared/static/wasm/sx/hs-compiler.sx
index cf5aad15..05504731 100644
--- a/shared/static/wasm/sx/hs-compiler.sx
+++ b/shared/static/wasm/sx/hs-compiler.sx
@@ -1832,6 +1832,9 @@
                     (hs-to-sx (nth ast 2))))
                 ((= head (quote set-el!))
                   (list (quote hs-set-element!) (hs-to-sx (nth ast 1)) (hs-to-sx (nth ast 2))))
+                ((= head (quote view-transition!))
+                  (let ((body (nth ast 2)))
+                    (list (quote hs-view-transition!) (hs-to-sx (nth ast 1)) (if (nil? body) (quote nil) (hs-to-sx body)))))
                 ((= head (quote put!))
                   (let
                     ((val (hs-to-sx (nth ast 1)))
diff --git a/shared/static/wasm/sx/hs-parser.sx b/shared/static/wasm/sx/hs-parser.sx
index dc70ed29..0f631c2b 100644
--- a/shared/static/wasm/sx/hs-parser.sx
+++ b/shared/static/wasm/sx/hs-parser.sx
@@ -2711,6 +2711,16 @@
                 (do (adv!) (list (quote exit))))
               ((and (= typ "keyword") (= val "js"))
                 (do (adv!) (parse-js-block)))
+              ((and (= typ "keyword") (= val "start"))
+                (do
+                  (adv!)
+                  (expect-kw! "view")
+                  (expect-kw! "transition")
+                  (let ((using (if (match-kw "using") (parse-expr) nil)))
+                    (match-kw "then")
+                    (let ((body (parse-cmd-list)))
+                      (match-kw "end")
+                      (list (quote view-transition!) using body)))))
               (true (parse-expr))))))
       (define
         parse-cmd-list
@@ -2767,7 +2777,8 @@
                 (= v "pick")
                 (= v "ask")
                 (= v "answer")
-                (= v "js"))))
+                (= v "js")
+                (= v "start"))))
           (define
             cl-collect
             (fn
diff --git a/shared/static/wasm/sx/hs-tokenizer.sx b/shared/static/wasm/sx/hs-tokenizer.sx
index 8b3a6a80..02255e1a 100644
--- a/shared/static/wasm/sx/hs-tokenizer.sx
+++ b/shared/static/wasm/sx/hs-tokenizer.sx
@@ -131,6 +131,7 @@
     "append"
     "settle"
     "transition"
+    "view"
     "over"
     "closest"
     "next"