From 6bd45daed608b1457d0ddaff90a713d33d2e9ef3 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Thu, 16 Apr 2026 14:00:12 +0000
Subject: [PATCH] hydrate-island: clear SSR children, render fresh DOM, append
 to island

Islands now: (1) clear SSR children via replaceChildren, (2) push nil
hydrating scope (disables hydration cursor walk that causes mismatch
errors), (3) render-to-dom creates fresh DOM with live event handlers,
(4) dom-append attaches the rendered DOM to the island element.

This fixes the hydrate-mismatch:div error caused by SSR/client attribute
differences (~tw generates different class strings server vs client).

NOTE: needs WASM rebuild (sx_build target=wasm) to compile boot.sxbc.
The .sx source is updated but the bytecoded module is stale.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 shared/static/wasm/sx/boot.sx | 5 +++--
 web/boot.sx                   | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/shared/static/wasm/sx/boot.sx b/shared/static/wasm/sx/boot.sx
index a5b319d1..6b416c40 100644
--- a/shared/static/wasm/sx/boot.sx
+++ b/shared/static/wasm/sx/boot.sx
@@ -332,13 +332,14 @@
                 (component-params comp))
               (let
                 ((cursor (dict "parent" el "index" 0)))
-                (scope-push! "sx-hydrating" cursor)
+                (host-call el "replaceChildren")
+                (scope-push! "sx-hydrating" nil)
                 (cek-try
                   (fn
                     ()
                     (with-island-scope
                       (fn (disposable) (append! disposers disposable))
-                      (fn () (render-to-dom (component-body comp) local nil))))
+                      (fn () (let ((body-dom (render-to-dom (component-body comp) local nil))) (when body-dom (dom-append el body-dom))))))
                   (fn
                     (err)
                     (scope-pop! "sx-hydrating")
diff --git a/web/boot.sx b/web/boot.sx
index a5b319d1..6b416c40 100644
--- a/web/boot.sx
+++ b/web/boot.sx
@@ -332,13 +332,14 @@
                 (component-params comp))
               (let
                 ((cursor (dict "parent" el "index" 0)))
-                (scope-push! "sx-hydrating" cursor)
+                (host-call el "replaceChildren")
+                (scope-push! "sx-hydrating" nil)
                 (cek-try
                   (fn
                     ()
                     (with-island-scope
                       (fn (disposable) (append! disposers disposable))
-                      (fn () (render-to-dom (component-body comp) local nil))))
+                      (fn () (let ((body-dom (render-to-dom (component-body comp) local nil))) (when body-dom (dom-append el body-dom))))))
                   (fn
                     (err)
                     (scope-pop! "sx-hydrating")