Dense, no-scroll mobile layout

layout-and-composition and grid-and-spacing cover the general system. This skill is the specific discipline of getting a screen to do its job within one viewport so the user isn't endlessly scrolling a tall stack of full-width cards. The goal is not "ban scrolling" — it's "scroll only when there's genuinely more content than screen, never because the layout wastes space."

Core principle: a phone screen is a fixed budget. Spend it on what the user came for; demote everything else off-screen, behind a tap, or into a denser form. A tall single-column stack of one-thing-per-card is the default failure mode — it's easy to build and wastes 60% of the budget on padding and headers.

1. Budget the viewport (know your numbers)

Logical points of content height after chrome, on common iPhones (portrait):

• Small (SE-class): ~667pt total, ~480–520pt usable between status/nav and the floating tab bar.
• Standard (15/16/17): ~852pt, ~650–690pt usable.
• Max/Pro Max: ~932pt, ~720–760pt usable.

Design the primary job to fit the smallest target's usable budget (~500pt). If the core task (see today's numbers / log a meal / check progress) needs scrolling on an SE, the layout is too loose. Everything below the fold is "more," not "the point."

2. The condensing playbook (in order of preference)

1. Merge cards. One full-width card per metric is the worst offender. Combine related metrics into a single card with internal columns/rows. Five metric cards (≈110pt each ≈ 550pt) → one 4-up stat grid (≈140pt).
2. Go horizontal. A 2×2 or 1×N grid (LazyVGrid/Grid) or a horizontally-scrolling rail puts 4 items in the height of 1. Use for stats, quick-actions, day pickers.
3. Segmented swap instead of stack. If a screen shows "macros AND nutrients AND trends," don't stack all three — put a segmented Picker at top and swap the body. Same pixels, one section at a time, zero scroll.
4. Disclosure / progressive reveal. DisclosureGroup, "Show more", or a .medium detent sheet for the long tail. Default-collapse anything that's reference, not action.
5. Inline dense rows. A diary/list of items should be compact rows (title + value on one line, ~44pt), not cards-with-padding. Reserve cards for the 1–2 hero elements.
6. Promote one hero, demote the rest. Pick the single most important element (the calorie ring, the day total) and give it real space; make everything else compact.
7. Kill redundant chrome. Per-card titles, repeated section headers, big hero copy that restates the screen title — each eats 30–60pt. One header per region, not per card.

3. Components that buy density

• Stat grid: 2×2 or 4-up Grid of (value, label) pairs — 4 numbers in ~one card's height.
• Combined progress card: one ring or bar set (calories + the 3 macros) instead of four separate bars stacked.
• Segmented section switcher: Picker(.segmented) driving the body — the highest-leverage no-scroll tool on feature-heavy screens.
• Compact list rows: leading icon · title · trailing value, single line, dividers not cards.
• Horizontal rail: ScrollView(.horizontal) for day strips, quick-add chips, recent items.
• Detented sheet for entry/detail (see ios26-hig-patterns §3) — keeps the main screen short.

4. When scrolling IS correct (don't over-compress)

• A genuinely long, unbounded list (full food diary, transaction history, search results) — that's content, not layout waste. Make rows dense; scrolling is expected.
• Long-form reading (an article, terms). Don't cram.
• When compressing would push elements below 44pt targets, clip text the user needs, or stack things so tightly they read as one blob. Density has a floor: 8pt minimum gaps, 44pt targets, AA contrast, comfortable line length. Compress whitespace and redundant chrome first; never compress legibility or tap safety.

The test: if a new user opened this screen, is the thing they came for visible without scrolling? If yes and the rest is honestly "more," you're done. If the core task is below the fold, condense.

5. Per-screen procedure (apply to each screen)

1. State the screen's one job in a sentence. That element is the hero — it gets prime, above-fold space.
2. List every other element; tag each: needed-now (keep, compact) / reference (disclose or move) / secondary action (toolbar or sheet) / redundant (delete).
3. Replace stacked metric cards with a stat grid or combined card.
4. If ≥2 distinct content modes coexist, add a segmented switcher and swap.
5. Move entry/detail into a detent sheet.
6. Re-measure against the SE budget (~500pt). Iterate until the job fits.
7. Verify the floor: 44pt targets, 8pt min gaps, AA contrast, Dynamic Type still reflows.

6. Review checklist

• ] Screen's one job is visible without scrolling on a small iPhone.
• ] No run of ≥3 single-metric full-width cards (merged into a grid/combined card).
• ] Coexisting modes use a segmented swap, not a long stack.
• ] Reference/long-tail content is disclosed or in a sheet, not inline.
• ] List items are compact rows, not padded cards.
• ] One header per region; no per-card title restating the screen.
• ] Density floor intact: ≥44pt targets, ≥8pt gaps, AA contrast, Dynamic Type reflows.
• ] Any remaining scroll is genuine content overflow, not wasted space.