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perf(core): let a scene wait when it only looks inside its own root #5726

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Merged
miguel-heygen merged 1 commit into from
Oct 18, 2026
Merged

perf(core): let a scene wait when it only looks inside its own root #5726

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30 changes: 30 additions & 0 deletions packages/core/src/compiler/htmlBundler.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3441,6 +3441,36 @@ ${["b", "h"].map((id, i) => ` <div data-composition-id="${id}" data-compositi
]);
});

it("lets a scene wait when its script only marks a node in its own root or reads an attribute off <html>", async () => {
const scene = (id: string, script: string) =>
`<template id="${id}-template"><div data-composition-id="${id}" id="r-${id}"><p>${id}</p>
<script>${script}</script></div></template>`;
const claim = (id: string) =>
`const root = (function(){var a=document.querySelectorAll('[id="r-${id}"]');for(var i=0;i<a.length;i++){if(!a[i].__hfClaimed){a[i].__hfClaimed=1;return a[i];}}return document.getElementById('r-${id}');})();`;
const dir = makeTempProject({
"index.html": `<!doctype html><html><head></head><body>
<div data-composition-id="main" data-width="1920" data-height="1080" data-duration="8">
${["g", "h", "i", "j"].map((id, i) => ` <div data-composition-id="${id}" data-composition-src="compositions/${id}.html" data-start="${i * 2}" data-duration="2"></div>`).join("\n")}
</div></body></html>`,
"compositions/g.html": scene("g", claim("g")),
"compositions/h.html": scene(
"h",
'JSON.parse(document.documentElement.getAttribute("data-composition-variables") || "[]");',
),
"compositions/i.html": scene("i", "document.documentElement.classList.add('dark');"),
"compositions/j.html": scene("j", "window.__hfClaimed = true;"),
});
const doc = parseHTML(await bundleToSingleHtml(dir, { sceneParts: true })).document;
const eager = (id: string) =>
doc.querySelector(`div[data-hf-scene="${id}"]`)?.getAttribute("data-hf-scene-eager");
expect(["g", "h", "i", "j"].map(eager)).toEqual([
null,
null,
"its script uses documentElement",
"its script uses window.__hfClaimed",
]);
});

it("marks a scene whose own script leaves work running as not swappable, and only that scene", async () => {
const dir = makeTempProject({
"index.html": `<!doctype html><html><head>
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6 changes: 3 additions & 3 deletions packages/core/src/compiler/inlineSubCompositions.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -70,10 +70,10 @@ function sceneScriptSwapRefusal(script: string): string | null {
return match ? `its script uses ${match[0].trim()}` : null;
}

// What ties a scene script to boot order: reaching outside its root, or leaving state on window for
// other scripts (the timeline registry aside).
// What ties a scene script to boot order: reaching outside its root (reading <html>'s attributes and
// marking nodes its scoped `document` found stay inside), or leaving state on window for others.
const REACHES_OUTSIDE_RE =
/\b(documentElement|getElementsBy\w+|__hf[A-Z]\w*)\b|document\s*\.\s*(head|body)\b|querySelector(All)?\(\s*["'](head|body)["']|defineProperty\s*\(\s*(window|globalThis|self|document)\b|\b(window|globalThis|self)\s*(\.\s*(?!__timelines\b)[A-Za-z_$][\w$]*|\[[^\]]*\])\s*=(?!=)/;
/\bgetElementsBy\w+\b|\bdocumentElement\b(?!\s*\.\s*(?:get|has)Attribute\s*\()|(?<!\.\s*)\b__hf[A-Z]\w*\b|\b(?:window|globalThis|self)\s*\.\s*__hf[A-Z]\w*|document\s*\.\s*(head|body)\b|querySelector(All)?\(\s*["'](head|body)["']|defineProperty\s*\(\s*(window|globalThis|self|document)\b|\b(window|globalThis|self)\s*(\.\s*(?!__timelines\b)[A-Za-z_$][\w$]*|\[[^\]]*\])\s*=(?!=)/;

@terencecho terencecho Oct 17, 2026

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[P2] Keep shared-object __hf* properties eager

The dotted-property exception also admits document.__hfSharedTone, although the scoped document is a Proxy over the real Document, with only the three query getters overridden and no private set trap (compositionScoping.ts:395–405). Two authored data-composition-src scenes can therefore share this property. Put a preparer first in source order at start=60/duration=5 that assigns document.__hfSharedTone = 'ready', followed by a reader at start=30/duration=5 that snapshots String(document.__hfSharedTone || 'unset') into its scoped .out. Each can register only its own timeline, with a 70-second root and no cross-scene registry/selector dependencies.

BASE marks both eager and initial mounting runs preparer then reader, producing ready. HEAD marks neither eager: the reader mounts at t=20 and captures unset; the preparer only mounts at t=50. takeHeldScenesNear removes each entry once, so later preparation does not repair the reader's visible text. The same overly broad receiver assumption admits aliases such as const page = window; page.__hfReady = 'ready', despite the window proxy forwarding that write globally. Preserve shared-receiver eagerness or establish that the receiver is actually a scene-local node. This is a source-derived ordering witness, not a claimed executed reproduction.

@terencecho terencecho Oct 17, 2026

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[P2] Preserve ordering for mutable shared <html> attribute reads

documentElement falls through the scoped document proxy to the real outer <html>. A getter writes nothing, but can still depend on its position relative to an eager writer. For example, start with <html data-shared-tone='warm'>; put a reader scene first in source order at start=30/duration=5 that snapshots document.documentElement.getAttribute('data-shared-tone') into its scoped .out, then a writer at start=60/duration=5 that calls document.documentElement.setAttribute('data-shared-tone', 'cool'). Use a 70-second root and only own-key timeline registrations.

BASE keeps both eager, so the reader captures warm before the writer changes the attribute. HEAD defers the reader but keeps the writer eager: the writer runs at initial mounting, and the reader captures cool at t=20 instead. Neither registry dependency closure nor the unchanged no-swap marker preserves this ordering; held-scene scheduling does not consult no-swap. Restrict the exemption to guaranteed-immutable reads or preserve their ordering dependencies, rather than allowing arbitrary getAttribute/hasAttribute calls. This is a source-derived BASE/HEAD control, not a claimed browser test.


/** Why an authored scene script must run at boot rather than when the playhead nears, or null. */
function sceneScriptEagerReason(script: string): string | null {
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