Mobile clip player: pin the video, tab the drills

The smell

After the active drills landed (52e8f51), the player was honest but unusable: video → controls → title → record → dictation → chunk-order → scenario → analysis, all stacked in one ScrollView. Three concrete problems, surfaced by the owner — "저 ui가 너무 사용성이 떨어져보이지않니":

1. Endless scroll — scenario and analysis sections were always expanded, so the screen was a long wall.
2. The video scrolled away — to reach a drill you lost sight of the clip you were supposed to be hearing. In a shadowing app that's backwards.
3. No "what do I do now" — the listen → reorder → produce flow was implied by stacking order, never guided.

The fix (52e8f51)

Picked "video pinned + drill tabs" over a guided step-wizard or a tidy accordion (the owner chose it from three ASCII mockups). The video now lives in a fixed header that never scrolls, with a tab bar below — Listen / Order / Speak / Shadow / Notes — and only the active drill renders, in its own scroll area. Two follow-through details:

• Drills take an embedded prop so, as the sole content of a tab, they open straight into the exercise instead of behind a "tap to start" button (one less tap).
• Tabs with no data yet show a placeholder ("Analyzing… ready soon" / "Not available for this clip") instead of a blank pane, so a still-analyzing clip reads as pending, not broken.

Portrait (Shorts) video is capped harder (~42% height) now that it's pinned, to leave room for the drill beneath it.

Pattern

In a media-centric learning screen, the media is not a section — it's the frame. Pin it and switch the work beside/below it, rather than stacking the work in a scroll that pushes the media out of view. The redesign was zero new data — pure layout — which is the cheapest kind of "advancement" when the features already exist.