[miguel-heygen]

What

Player and NLEPreview take a new prop, loadingUi: "studio" | "host" (default "studio"). With "host", the host draws its own loader, so Studio draws neither of its preview loaders: neither the "Loading composition" cover nor the "Preparing preview assets" wait. onCompositionLoadingChange still reports that the preview is loading. suppressLoadingOverlay is unchanged.

Why

A host that draws its own loader over the preview had no way to turn off both of Studio's. suppressLoadingOverlay hides only the composition cover, and the asset wait is its own black overlay.

Folding the asset wait into suppressLoadingOverlay would have changed Studio's own preview pane: PreviewPane passes suppressLoadingOverlay after the first load to skip only the composition cover on later loads, and those loads keep their asset wait. So "skip the cover on a later load" and "the host draws its own loader" are two props.

Found on the way, not changed here

Studio's asset wait never starts on a real first load today. The player's iframe fires load for about:blank first, so the composition's own load is load 2, and Player treats any load after the first as a content refresh and skips the asset scan. A log line in Player's load handler, on a Linux box at this branch's base, showed exactly that: the first load was about:blank with no media, the second was the composition with its video still unloaded, and that second one skipped the scan as a refresh.

So this PR is a guard: it keeps a host's loader alone on screen once that path runs again. Whether to revive the asset wait (count only the composition's load) or delete it is a separate product decision; this PR leaves it as it is.

Related work

The player element already has the matching opt-out for its own overlay, assets-loading-ui="none".

How

• Player.tsx keeps whether each wait is on (compositionWaitShown, assetWaitShown, the same conditions as before) apart from whether Studio draws it (studioDraws(wait, loadingUi)). The loading callback reads the waits, not the drawing, so callers hear exactly what they heard before. NLEPreview passes loadingUi to the live preview slot.
• To stay under the file-size and complexity budgets, NLEPreview's stage constants (PREVIEW_STAGE_INSET_PX, SHADOW_IFRAME_STYLE, resolvePreviewStageSize) move unchanged into nle/previewStage.ts, and Player reads loadingUi from its remaining props instead of destructuring one more.

Test plan

• Two tests in Player.test.ts. One loads a preview whose audio has no data with suppressLoadingOverlay alone: the asset wait still shows (PreviewPane's meaning, unchanged). The other uses loadingUi: "host": neither "Preparing preview assets" nor "Loading composition" is drawn, and onCompositionLoadingChange was last called with true.
• fails without the fix: run before the change, the loadingUi: "host" test fails with expected 'Preparing preview assetsWaiting for m…' not to contain 'Preparing preview assets'; the other passes.

Before (shot-only setup)

Studio at this branch's base, preview pane passing suppressLoadingOverlay as a host does, a video whose first 300 KB arrive and the rest is held: Studio's black asset wait covers the picture.

After (shot-only setup)

The same at this head with loadingUi="host": Studio draws nothing over the picture; the host's own loader would sit there.

Both shots are shot-only setups, labelled as such and never committed: the preview pane edited to pass the host's props, the player's own overlay off with assets-loading-ui="none" (as a host sets it), and one line in Player so the composition's load counts as the first (see "Found on the way"). Without that line neither state shows any Studio loader.

What I measured

• Player.test.ts + NLEPreview.test.ts: 50 of 50 pass, 3 runs in a row, on a Linux box.
• tsc --noEmit -p packages/studio: exit 0. fallow audit against the merge-base with --fail-on-issues: exit 0. comment-ratchet.mjs and check-comment-citations.mjs against the merge-base: both pass. NLEPreview.tsx is 560 lines.

What I did NOT execute

• No unpatched browser run that shows the difference: with the first-load counting as it is, neither Before nor After draws a Studio loader.
• No change or test for the hidden shadow and backdrop preview slots in NLEPreview; they already pass suppressLoadingOverlay and sit behind the live slot.

Size

About 100 changed lines, half of them the unchanged stage constants moving file: one prop, one behaviour, the two tests that pin it, and the moves the size and complexity budgets asked for.

[heygengenesis]

Reviewed at b90a8e2d. I found no blocker in the code, but two required repo checks are red on this head, so I'm requesting changes until they pass.

Blockers (CI):

1. Comments / "A package file's comment share may not rise": NLEPreview.tsx goes from 13 to 14 comment lines and Player.tsx from 60 to 62, which raises each file's comment share. Cut those comment lines or move the meaning into names or types. For example, loadingUi: "studio" | "none" could become a self-describing union, or the doc lines could be dropped from the NLEPreview pass-through.
2. PR captures / "Require Before and After captures": this PR changes .tsx in packages/studio, so the body needs ## Before and ## After sections, each with an image or video. Per the check's hint, edit the body text first, then attach with gh pr edit 6911 --attach.

Code: no issues found.

• compositionWaitShown and assetWaitShown use the same conditions the old show* flags did, and drawing is now gated separately on loadingUi === "studio". Defaults and the PreviewPane path are unchanged, and onCompositionLoadingChange reports exactly what it did before.
• Player.test.ts and NLEPreview.test.ts pass 50/50 at this head. With Player.tsx and NLEPreview.tsx reverted to main, only the loadingUi: "none" test fails, with the message quoted in the body. That matches the fails without the fix: line.

Non-blocking: with loadingUi: "none" the host also loses Studio's "Continue anyway" button. The asset poll's 10 s cap still ends the wait, so nothing hangs. A Desktop loader that wants that escape would need an imperative hook later.

[github-actions]

Edit accuracy: accurate 271 (base branch 271), smooth 122 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 true, 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

[heygengenesis]

Re-reviewed at ac0e8733. The code is fine, but one required check is still red and the body no longer matches the code, so I'm requesting changes again.

Resolved: the Comments check now passes. loadingUi: "studio" | "host" reads clearly without the doc lines, and Player.test.ts plus NLEPreview.test.ts pass 50/50 at this head.

Still blocking:

1. PR captures / "Require Before and After captures" still fails on this head. The body has no ## Before or ## After section. This change edits .tsx in packages/studio, so the check needs both, each with an image or video. Edit the body text first, then run gh pr edit 6911 --attach ./before.png --attach ./after.png.
2. The body describes the old API. What, How, Test plan, the fails without the fix: line and "What I did NOT execute" all still say loadingUi: "none", but the prop is now "studio" | "host". Please update the body to "host" in the same edit as the captures, so the named failing test matches the code.

The code itself has no remaining issues.

[heygengenesis]

Re-reviewed at 5825d4ab. Requesting changes for a formatting failure only; the code is ready.

Blocker (CI): bun run format:check fails on packages/studio/src/components/nle/NLEPreview.tsx. The CI "Format" job and preview-regression's "Preflight (lint + format)" job both fail on it, so preview-regression is red too. I see the same result locally with oxfmt --check. Two spots need fixing:

• line 31: the ./previewStage import is over the print width and needs wrapping onto multiple lines;
• lines 70–71: two blank lines are left where the stage constants were moved out.

Running bunx oxfmt packages/studio/src/components/nle/NLEPreview.tsx fixes both.

Resolved since the last head:

• The description now has Before and After captures, and the PR captures check passes.
• The description now matches the code (loadingUi: "studio" | "host"), including the fails without the fix: line.
• The Comments check passes.

Code: no issues found.

• studioDraws(wait, loadingUi) gates only the drawing, and onCompositionLoadingChange still reports the waits, so the default and PreviewPane behaviour is unchanged.
• The constants moved into previewStage.ts are unchanged, and their only importers are NLEPreview.tsx and NLEPreview.test.ts.
• tsc --noEmit -p packages/studio is clean. Player.test.ts and NLEPreview.test.ts pass 50/50.

Noted, not blocking: the "Found on the way" finding that the asset wait never runs on a real first load (the about:blank load counts as load 1) deserves its own issue.

[miguel-heygen]

Fixed in 3a7d5839: oxfmt wraps the ./previewStage import and drops the doubled blank line in NLEPreview.tsx; Format and Preflight pass at that head.

[heygengenesis]

Re-reviewed at 3a7d5839. Approving.

• Formatting only: the only change since 5825d4ab is one fast-forward commit, 3a7d5839 style(studio): format NLEPreview's stage import. It wraps the ./previewStage import and removes the extra blank line. No behaviour changed.
• oxfmt --check passes on NLEPreview.tsx, previewStage.ts and Player.tsx.
• CI at this head: all 8 workflow runs completed successfully: CI, preview-regression, Comments, PR captures, regression, Player perf, Windows render verification and CodeQL.

My review of 5825d4ab covers the code: no issues, and the fails without the fix: test was verified earlier.