[valeriangalliat]

🤖 AI agent: Arcade fork patch. Do not merge.

This draft shows patch/probe-var-src-media against main, the upstream mirror, so the patch has one page for its diff, its revisions and its reason. Arcade's /hyperframes-update rebases the branch onto main and cherry-picks it onto arcade; this PR is not part of that flow. When a rebuild changes the patch, its git range-diff against the previous sync/<date>/probe-var-src-media tag is posted as a comment.

Not needed yet and not in scripts/arcade/patches.json. Arcade doesn't use data-var-src today. This is the prerequisite for moving scene settings onto HyperFrames variables (ARC-17433), and the first candidate to send upstream. Split out of #13.

Why

hasVariableBoundMedia only probes when render-level --variables set the bound variable. A value from the composition's declared default or a host's data-variable-values is applied by the runtime in the browser, while extraction reads the static src, so the export shows the fallback clip. HyperFrames' own lint treats a default that differs from src as normal (the src is the authored fallback), and its docs present data-variable-values as the way to give each instance its own values.

While inlining, the compiler now stamps data-hf-var-src-changed on bound <audio>, <video> and <source> when any value in its scope chain differs from the static src: the top-level declared defaults, or any enclosing composition's merged defaults and host values. The trigger probes when it sees the stamp. A bound clip whose value equals its src doesn't load the page. The comparison runs before remote sources are localized, while both still read as authored.

Review notes

• The stamp checks every value the scope chain could supply rather than replicating the runtime's lookup, so a doubtful case loads the page and never exports a stale clip. The inlined scene keeps its authored data-composition-id inside the host's runtime id, which is why a nearest-scope lookup alone misses the host's values.
• Same pattern as data-hf-auto-start: compiler stamps, probe trigger reads.
• Images are unchanged: they render live in the page.

Verification

• htmlCompiler.test.ts: a compiled sub-composition is stamped when the host value differs, stamped when the declared default differs, and left alone when the host value equals the src.
• probeStage.test.ts: stamped versus unstamped bound clip. Upstream's hasVariableBoundMedia tests unchanged. 228/228 across both files. tsc, oxfmt, oxlint and lefthook clean.
• Arcade render corpus on prod's a318cd008 plus this change (bundled with Fork patch: Probe untraced media src writes #13 at the time): two temporary data-var-src scenes, scene default and host override, pass; both export the stale clip without it.

Upstream

No issue or PR filed yet. Strong candidate: it's a gap in HyperFrames' own variables feature.

Drop when

Upstream probes data-var-src media whose declared default or host value differs from its src.

Arcade

ARC-17433 · ARC-17431

[github-actions]

Edit accuracy: accurate 271 (base branch 271), smooth 150 of those

The gate passes.
Smoothness is reported in the artifact, not gated. A case fails only if it fails 2 of 3 runs.

Quarantined, measured but not gated (0)

Unstable (1)

• seqplainkeys-none-center-r0-root-z100: tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo false, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true

[valeriangalliat]

🤖 AI agent: Dropped at sync/2026-11-10. Upstream heygen-com/hyperframes#6501 (v0.8.207) loads the page for data-var-src media when the value comes from a mount's data-variable-values or a declared default on the root; both render correctly on 0.9.30, which the fork is now based on.

One case is left upstream: a default declared in the sub-composition file itself, with no value from the mount. That is reported as heygen-com/hyperframes#7505 with a repro. It is not carried here, because a host can pass the value on the mount instead.

The patch's history stays under the sync/2026-11-09/probe-var-src-media tag.