* fix(core): discover sub-composition hosts to a fixed point during inlining
inlineSubCompositions collected [data-composition-src] hosts from the
document once, before inlining began, then processed that fixed list in
a single flat loop. A host's inlined content could introduce new hosts
of its own (a sub-composition nesting another sub-composition), and
those were never discovered: two-level nesting worked because the
second level's host already existed in the root document, but any
third level's host only appeared inside content the single pass had
already finished walking, so its content silently never rendered.
Host discovery now runs as a work queue: after a host is inlined, the
newly inserted subtree is re-scanned for further hosts, which are
enqueued with their ancestry chain. A host whose source already appears
in its own ancestry is a circular reference and is reported through the
existing onMissingComposition channel instead of being inlined; a depth
ceiling backstops any gap in that check. Existing single- and two-level
fixtures are unaffected.
* fix(producer): assign runtime composition ids to hosts discovered mid-inline
The producer's per-instance runtime id assignment (assignBundledRuntimeCompositionIds)
ran once over the root document's initial hosts, before inlining. With
host discovery now iterating to a fixed point (previous commit), hosts
revealed inside an already-inlined sub-composition were never in that
pre-pass, so the identity map returned undefined for them: two sibling
instances of the same sub-composition, discovered mid-traversal, both
fell back to their shared authored id and clobbered each other's
variablesByComp entry.
hostIdentityMap is now a lazy map: a pre-pass cache hit returns
unchanged, a miss reads the host's authored data-composition-id,
allocates a collision-checked runtime id by scanning the live document,
writes it back, and caches it. No change to the shared inliner's call
signature. Existing single-instance and root-level reusable-template
cases (#2064) are unaffected.
* test(producer): add depth-3 nested sub-composition regression fixture
Adds a minimal three-level chain (root -> level-2 -> level-3) where the
deepest level renders a distinguishing full-frame marker, following the
existing sub-comp-* fixture pattern. Confirmed against the pre-fix
commit (735128a61) in a separate scratch checkout that the fixture fails
without the previous two commits (level-3's marker absent, ~0.4B fewer
matching pixels than the golden expects) and passes with them.
The golden reference video was captured on the team's render host
(devbox) rather than locally, to avoid PSNR drift from font/GPU
differences against whatever renders the regression suite in CI. Local
render against that golden also passes (PSNR ~24.5dB throughout, 0
failed frames of 100 checkpoints), confirming cross-machine consistency
as well.
## Summary
The Studio preview now installs the runtime bridge only after its transport is ready, preventing initialization-order gaps without changing the bridge contract.
## Stack
Part 1 of 20. Parent: `main`. Next: heygen-com/hyperframes#2559. The golden reference, heygen-com/hyperframes#2387, remains open and unchanged.
## Test plan
- [x] Integrated Studio suite: 2,800 tests passed
- [x] Integrated parser suite: 853 tests passed
- [x] Studio and parser typechecks passed
- [x] Studio and parser production builds passed
- [ ] Per-PR CI completes on the submitted stack
## Post-Deploy Monitoring & Validation
Validation window: first 24 hours after the stack merges. Owner: Studio maintainers. Watch browser console and support reports for `[Timeline]`, `gsap-parser`, failed keyframe mutations, or preview/render easing mismatches. Healthy means edits persist and preview/render agree; revert the first failing layer if authored animation data changes unexpectedly.
---
[](https://github.com/EveryInc/compound-engineering-plugin)
* docs(guides): resolve the fidelity contradiction (preserve substance, adapt form)
The guide called the rebuild 'lossy by nature' while the checklist demanded 'content
match the brief exactly', with no rule for what to preserve vs adapt. On a live import
CD kept fonts/palette/hero but genericized the source's real figures (2.4M signals/sec,
+240% spike) into vague phrases. Resolve around one principle: substance (real copy,
exact palette/fonts, distinctive figures/data, product names, signature visuals) is
preserved verbatim; only the form (static page to timed multi-scene motion) adapts.
* test(guides): pin the Send-to fidelity contract against silent regression
Address review on #2620: the resolved 'preserve substance, adapt form' instruction is
load-bearing LLM-facing prompt text, but validate-docs only proves syntax. Add a semantic
pin (mirroring packages/cli figma skillContent.test.ts) asserting the three positive
concepts are present and the two retired contradictory phrases ('lossy by nature',
'content match the brief exactly') cannot silently return.
* style(guides): oxfmt the Send-to fidelity-contract test
Wrap the readFileSync call to oxfmt form (printWidth 100); unblocks required Format + its
preflight/preview-regression cascade on #2620.
* fix(producer): credit held video tails in coverage gate
* test(producer): decouple makeExtracted's durationSeconds default from delivered frame count
Defaulting durationSeconds to delivered/fps made any test modeling a
delivery shortfall silently report full coverage unless it remembered
to override durationSeconds afterward. Default to Infinity instead so
callers fall into the 'no usable source duration' branch (full slot
required) unless they explicitly pass a duration.
* fix(core): stop the async media-metadata rebind once render capture starts seeking
scheduleMetadataDurationHydration re-resolves and can swap the captured
GSAP timeline off a debounced loadedmetadata/durationchange event, fully
uncoordinated with the producer's own per-frame renderSeek calls. When a
full-length <video>'s metadata resolves after capture has already begun
(slow I/O, Docker), this races the deterministic BeginFrame capture loop
and can reflow sub-composition state mid-render, producing phase-offset
duplicate content in captured frames (#2550).
Render-mode duration correction already happens deterministically during
the probe stage before capture starts, so once renderSeek has been called
once there is nothing left for this self-correction to do — gate it off
for the rest of the session.
* fix(core): scope the metadata-rebind guard to actual render/export pages
renderSeek isn't capture-exclusive — Studio's own preview iframe falls
back to it for compositions whose timeline overhangs every native
adapter's duration. Gating the HF#2550 fix on renderCaptureSeekStarted
alone silently disabled the metadata-driven duration self-correction for
that live-scrub case too, where it's still needed. Require the render/
export page signal (window.__HF_EXPORT_RENDER_SEEK_CONFIG, set only by
the producer's fileServer.ts) alongside it, and add a regression test
covering the Studio-preview case.
* fix(engine): stop requesting beyond-viewport capture for video comps that don't need it
Root-caused HF#2550 by reproducing the reporter's public repro end-to-end
(not just the timeline-rebind mechanism from the earlier commits in this
branch) on native Linux: instrumented the actual DOM state during a real
capture session and confirmed the sub-composition never double-mounts —
getBoundingClientRect and the timeline's own local time both match the
single, correct DOM tree throughout. The phantom second copy only exists
in the captured screenshot pixels.
Bisected it to captureBeyondViewport: resolveVideoCaptureBeyondViewport
(#1094's tall-portrait fix) forces `Page.captureScreenshot`'s beyond-viewport
path on for any render with a native <video>, regardless of whether the
page's content actually overflows the declared capture height. On
SwiftShader that beyond-viewport path can composite a stale, vertically
offset paint of the page alongside the fresh one for content that fits
entirely within the viewport — producing exactly the reported phase-offset
duplicate. Disabling captureBeyondViewport (repro's video still present)
eliminates the duplicate outright; re-enabling it reproduces the duplicate
byte-for-byte, isolating it as the actual cause.
Adds pageContentExceedsCaptureHeight, a ground-truth measurement of the
page's actual scrollHeight against the requested capture height, and wires
it into initializeSession to downgrade captureBeyondViewport back to false
once the page is settled and it's confirmed unnecessary — the "reliable
clip predictor" the original #1094 fix's ponytail comment flagged as
missing. This keeps #1094's fix intact for content that genuinely
overflows while closing the SwiftShader ghosting hazard for the (common)
case of video that fits inside its own viewport.
* test(producer): add HF#2550 video+sub-composition regression fixture
Checks in the reporter's confirmed real-world reproduction (media
regenerated via ffmpeg testsrc2, matching their public repro repo) as a
regression fixture, with a golden baseline rendered against the fix.
Verified end-to-end via the project's own Docker regression harness:
- Rendering this fixture with the fix produces the golden baseline
(clean, single flowchart instance, captureBeyondViewport correctly
downgraded).
- Direct CLI renders (not through this harness) against unpatched code
reproduce the reported phantom-duplicate artifact reliably (10/10).
Caveat documented in meta.json: the underlying bug is timing-dependent.
Two harness runs against unpatched code, using this same fixture, did
not reproduce the artifact (0/2) — the harness's in-process render path
apparently doesn't hit the same race window a direct CLI process does on
this host. This fixture is a best-effort regression guard and a
preserved real-world repro, not the sole protection — the deterministic
guard is packages/engine/src/services/screenshotService.test.ts's
pageContentExceedsCaptureHeight unit tests, which exercise the actual
fix logic directly.
Also adds an .gitattributes LFS rule for this fixture's source
index.html (744 KB — carries the real project's embedded base64
assets, over the largefiles hook's 500 KB non-LFS limit).
* fix: route HF#2550 fixture binaries through LFS (were committed raw)
filter.lfs.clean/smudge were locally configured as a no-op "cat" in
this repo's shared .git/config, silently disabling LFS filtering for
every worktree. The previous commit's large binaries (output.mp4,
compiled.html, source index.html, source video) landed as raw blobs
instead of LFS pointers as a result. Ran `git lfs install --local
--force` to restore the correct filter commands, then re-staged the
affected files so they commit as proper LFS pointers.
* fix(engine): address capture viewport review feedback
slideshowIslandRegex scanned the full file content on every editingFile
change even for the common non-slideshow case. Gate it behind a plain
substring check on SLIDESHOW_ISLAND_TYPE first — cheap, and avoids the
full-content RegExp pass for files that plainly have no island.
Added a test for the still-open behavior this preserves: a malformed
island (invalid JSON) still trips the substring check and the regex,
so the tab stays discoverable rather than silently disappearing.
Flip STUDIO_FLAT_INSPECTOR_ENABLED's default from false to true — the
bug-fix pass on the flat inspector is complete (right-aligned values,
Stroke width/style split, promote-badge overlap, Layout/Style section
gating for non-visual elements like audio). VITE_STUDIO_FLAT_INSPECTOR_ENABLED=false
still opts back into the legacy panel.
Updates the two tests that asserted the old false default: the flag's
own default test, and the "classic PropertyPanel input coverage" suite,
which relied on that default to reach the legacy panel and now mocks it
explicitly (mirroring the adjacent "flat" suite's existing pattern).
The Slideshow tab rendered unconditionally, showing the branching editor
for any composition regardless of whether it was actually a slideshow —
a plain video comp offered a tab with nothing meaningful to edit.
Gate it on the composition carrying the slideshow JSON island
(<script type="application/hyperframes-slideshow+json">), the same
definitive marker the CLI's `present` command already requires (it
refuses to run without one). Presence-only, not full manifest
validation, so a malformed island still surfaces the tab rather than
disappearing entirely. Also bounce rightPanelTab off "slideshow" to
"renders" if the active composition stops being a slideshow while that
tab is open (e.g. switching files), since its button would otherwise
vanish with no way back to it.
Extracted the gating + scene-list derivation into useSlideshowTabState
to keep StudioRightPanel.tsx under the 600-LOC gate.
* feat(media): alpha-capable authoring proxies
Alpha sources were refused a proxy before the codec map ever asked whether the
browser could decode them, so a ProRes 4444 alpha file (which no browser
previews at all) rendered black forever, while an alpha WebM (which previews
fine) was already covered by the browser-safe check on the next line. The alpha
veto earned nothing and cost the one case that needed help.
Alpha is now a target-codec choice rather than a veto: alpha sources transcode
to VP9 + yuva420p in WebM, everything else keeps the existing H.264/MP4 path
byte for byte. Only files no browser can preview are proxied, which is the rule
the runtime already followed everywhere else.
WebM cannot carry AAC, so the VP9 path uses Opus and drops the MP4-only
faststart flag. PROXY_PARAMS_VERSION moves to v3 so clients stop serving the
previously cached proxies.
Safari does not decode VP9 alpha and still shows black for alpha sources, as it
does today: this is better on Chromium and Firefox and no worse anywhere.
* fix(media): infer proxy variant for rescue
* fix(media): preserve alpha proxy hardening after restack
* docs(media): document automatic proxying for hostile codecs
Describes the shipped behavior: which input codecs render, that live preview
auto-proxies what the browser cannot decode, where the cache lives, and how to
turn it off. Carries the skills notes and the hardening design documents.
* docs(media): align proxy guidance with runtime
James