Fix stepper hydration flash and stepping structure

Two bugs fixed:

1. Hydration flash: The effect's schedule-idle called rebuild-preview
   on initial hydration, which cleared the SSR HTML and re-rendered
   (flashing raw SX source or blank). Fix: skip rebuild-preview on
   initial render — the SSR content is already correct. Only rebuild
   when stepping.

2. Stepping structure: After do-back calls rebuild-preview, the DOM
   stack was reset to just [container]. Subsequent do-step calls
   appended elements to the wrong parent (e.g. "sx" span outside h1).
   Fix: compute the correct stack depth by replaying open/close step
   counts, then walk the rendered DOM tree that many levels deep via
   lastElementChild to find the actual DOM nodes.

Proven by harness test: compute-depth returns 3 at step 10 (inside
div > h1 > span), 2 at step 8 (inside div > h1), 0 at step 16 (all
closed).

Playwright test: lake never shows raw SX (~tw, :tokens) during
hydration — now passes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-04-02 14:42:40 +00:00
parent 9a64f13dc6
commit b13962e8dd
2 changed files with 91 additions and 46 deletions

View File

@@ -8,7 +8,8 @@
(if (client?) (def-store "home-stepper" (fn () {:step-idx (signal 16)})) nil))
(step-idx (if store (get store "step-idx") (signal 16)))
(dom-stack-sig (signal (list)))
(code-tokens (signal (list))))
(code-tokens (signal (list)))
(initial-render (signal true)))
(letrec
((split-tag (fn (expr result) (cond (not (list? expr)) (append! result {:expr expr :type "leaf"}) (empty? expr) nil (not (= (type-of (first expr)) "symbol")) (append! result {:expr expr :type "leaf"}) (is-html-tag? (symbol-name (first expr))) (let ((ctag (symbol-name (first expr))) (cargs (rest expr)) (cch (list)) (cat (list)) (spreads (list)) (ckw false)) (for-each (fn (a) (cond (= (type-of a) "keyword") (do (set! ckw true) (append! cat a)) ckw (do (set! ckw false) (append! cat a)) (and (list? a) (not (empty? a)) (= (type-of (first a)) "symbol") (starts-with? (symbol-name (first a)) "~")) (do (set! ckw false) (append! spreads a)) :else (do (set! ckw false) (append! cch a)))) cargs) (append! result {:spreads spreads :tag ctag :type "open" :attrs cat}) (for-each (fn (c) (split-tag c result)) cch) (append! result {:open-attrs cat :open-spreads spreads :tag ctag :type "close"})) :else (append! result {:expr expr :type "expr"}))))
(build-code-tokens
@@ -263,7 +264,36 @@
(let
((dom (render-to-dom expr (get-render-env nil) nil)))
(when dom (dom-append container dom)))))
(set-stack (list container))))))
(let
((depth 0) (all (deref steps)))
(let
loop
((i 0))
(when
(< i target)
(let
((stype (get (nth all i) "type")))
(cond
(= stype "open")
(set! depth (+ depth 1))
(= stype "close")
(set! depth (- depth 1))))
(loop (+ i 1))))
(let
((stack (list container)) (node container))
(let
walk
((d 0))
(when
(< d depth)
(let
((child (host-get node "lastElementChild")))
(when
child
(append! stack child)
(set! node child)))
(walk (+ d 1))))
(set-stack stack)))))))
(do-back
(fn
()
@@ -304,7 +334,7 @@
(build-code-tokens (first parsed) tokens step-ref 0)
(reset! code-tokens tokens)))))
(let
((_eff (effect (fn () (schedule-idle (fn () (build-code-dom) (rebuild-preview (deref step-idx)) (update-code-highlight) (run-post-render-hooks)))))))
((_eff (effect (fn () (schedule-idle (fn () (build-code-dom) (if (deref initial-render) (do (reset! initial-render false) (set-stack (let ((p (get-preview))) (if p (list p) (list))))) (rebuild-preview (deref step-idx))) (update-code-highlight) (run-post-render-hooks)))))))
(div
(~tw :tokens "space-y-4 text-center")
(div

View File

@@ -1,58 +1,62 @@
const { test, expect } = require('playwright/test');
const { loadPage, trackErrors } = require('./helpers');
test('stepper: no raw SX component calls visible after hydration', async ({ page }) => {
const t = trackErrors(page);
await loadPage(page, '');
test('stepper: lake never shows raw SX source during hydration', async ({ page }) => {
// Monitor the lake content during page load to catch flashes
const lakeStates = [];
await page.context().clearCookies();
const stepper = page.locator('[data-sx-island="home/stepper"]');
await expect(stepper).toBeVisible({ timeout: 10000 });
// Set up mutation observer before navigation
await page.addInitScript(() => {
window.__lakeStates = [];
const observer = new MutationObserver(() => {
const lake = document.querySelector('[data-sx-lake="home-preview"]');
if (lake) {
const text = lake.textContent;
if (text && text.length > 0) {
window.__lakeStates.push(text.slice(0, 100));
}
}
});
// Start observing once DOM is ready
if (document.body) {
observer.observe(document.body, { childList: true, subtree: true, characterData: true });
} else {
document.addEventListener('DOMContentLoaded', () => {
observer.observe(document.body, { childList: true, subtree: true, characterData: true });
});
}
});
const lake = stepper.locator('[data-sx-lake]');
await expect(lake).toBeVisible({ timeout: 5000 });
const lakeText = await lake.textContent();
expect(lakeText).not.toContain('~cssx/tw');
expect(lakeText).not.toContain('~tw');
expect(lakeText).not.toContain(':tokens');
await page.goto('http://localhost:8013/', { waitUntil: 'networkidle' });
await page.waitForTimeout(3000);
expect(t.errors()).toEqual([]);
const states = await page.evaluate(() => window.__lakeStates);
// No state should contain raw SX component calls
for (const state of states) {
expect(state).not.toContain('~tw');
expect(state).not.toContain('~cssx');
expect(state).not.toContain(':tokens');
}
});
test('stepper: default view shows all four words', async ({ page }) => {
// Clear stepper cookie
test('stepper: default view shows all four words after hydration', async ({ page }) => {
await page.context().clearCookies();
await loadPage(page, '');
const lake = page.locator('[data-sx-lake="home-preview"]');
await expect(lake).toBeVisible({ timeout: 10000 });
// Wait for hydration
await page.waitForTimeout(2000);
await page.waitForTimeout(3000);
const text = await lake.textContent();
// All four words should be present after hydration
expect(text).toContain('the');
expect(text).toContain('joy');
expect(text).toContain('of');
expect(text).toContain('sx');
});
test('stepper: all spans inside h1 with correct structure', async ({ page }) => {
await page.context().clearCookies();
await loadPage(page, '');
await page.waitForTimeout(3000);
const lake = page.locator('[data-sx-lake="home-preview"]');
const h1 = lake.locator('h1');
await expect(h1).toBeVisible({ timeout: 5000 });
// All colored spans should be inside the h1
const spans = h1.locator('span');
const count = await spans.count();
expect(count).toBeGreaterThanOrEqual(4);
});
test('stepper: stepping forward renders styled text', async ({ page }) => {
// Start from step 0
test('stepper: stepped spans have colored text', async ({ page }) => {
await page.context().addCookies([{
name: 'sx-home-stepper',
value: '0',
@@ -64,18 +68,29 @@ test('stepper: stepping forward renders styled text', async ({ page }) => {
const fwdBtn = page.locator('button:has-text("▶")');
await expect(fwdBtn).toBeVisible({ timeout: 5000 });
// Step forward 10 times to get through "of"
for (let i = 0; i < 10; i++) {
// Step forward 16 times to complete the expression
for (let i = 0; i < 16; i++) {
await fwdBtn.click();
await page.waitForTimeout(300);
await page.waitForTimeout(200);
}
const lake = page.locator('[data-sx-lake="home-preview"]');
const text = await lake.textContent();
expect(text).toContain('of');
// The "of" text should be in a styled span (with sx- or data-tw class)
const styledSpan = lake.locator('span[data-tw]').filter({ hasText: 'of' });
const count = await styledSpan.count();
expect(count).toBeGreaterThan(0);
// Check each span has a non-black computed color
const colors = await lake.evaluate(el => {
const spans = el.querySelectorAll('span');
return Array.from(spans).map(s => ({
text: s.textContent,
color: getComputedStyle(s).color,
hasClass: s.className.length > 0
}));
});
expect(colors.length).toBeGreaterThanOrEqual(4);
for (const span of colors) {
// Each span should have a class applied
expect(span.hasClass).toBe(true);
// Color should not be default black (rgb(0, 0, 0))
expect(span.color).not.toBe('rgb(0, 0, 0)');
}
});