fix(design-system): make the radius contract describe the app it governs

[jackwener]

Follow-up to #1520. Audited the radius system from first principles — the four tier values, every calc() shrink site, the COMPONENT_RADIUS table, and the SELECTOR_TIER table.

The suite was 18/18 green. It was green because the non-conforming parts were either absent from the tables or had the rule rewritten around them. Two contracts had gone further and were holding defects in place — the fix was the thing failing CI.

Contracts that were protecting defects

.providerLogo — a repaired invariant, silently reverted, then locked

PR-UI-13 pinned a single ~27-28% radius ratio across plate sizes, after an audit found the 44px and 32px plates reading as different shapes. The tier convergence rewrote both to --radius-surface:

plate	radius	ratio	comment claimed
44px	8px	18.2%	/* 27.3% — anchor ratio */
32px	8px	25.0%	/* 28.1% — matches md ratio */

Both comments arithmetically false, the drift restored, and SELECTOR_TIER pinned it — restoring the ratio failed CI.

Square icon plates are governed by ratio, not tier: a fixed px cannot read the same at 32px and 48px. Added --radius-plate: 27% — scale-invariant, restores the PR-UI-13 anchor (12px at 44px), correct at sizes not yet added. Applied to all six plates, which had drifted to four different ratios (18.2 / 25 / 16.7 / 22.2%). The compact and catalog-row overrides no longer restate a radius at all; with a ratio the size change alone suffices.

Compared visually at all four sizes before merging — the old column visibly drifts (48px reads squarer than 32px), the new one is one shape scaled.

.maka-search-modal-input-row — concentric nesting that was never adjacent

Pinned to calc(var(--radius-modal) - 8px) = 4px as "an input inside a 12px modal shell with an 8px inset", warning that a tier "would read as too round against the shell corners".

Measured live: that row is the middle of a 3-row grid — 57px below the shell's top edge, 12px in from its sides, adjacent to no shell corner. The 8px was the vertical margin to the header band, an axis with nothing to do with the corner. Its twin .maka-palette-input-wrap — same primitive, same position, same 12px shell — used the control tier all along, so the two searches differed by 50% in roundness.

The rule itself was the root cause. It said only "with padding between them" and never mentioned adjacency, so the search modal satisfied it literally — and its one worked example was this bug. Rewritten to state the precondition: the inner corner must sit in the outer corner, with an equal inset on both edges meeting there. It now cites the one genuinely concentric site in the codebase (segmented: 8px track, uniform 2px pad, buttons hugging its corners, 8−2=6 landing exactly on control).

Rules that had been rewritten to fit the code

• TabsList / TabsTrigger were dropped from COMPONENT_RADIUS when refactor(ui): hover/selected state + tab component governance (post #496 color migrate) #499 moved them to primitives/tabs.tsx, on the stated grounds they were "governed by primitives-design-contract escape hatches". That file contains no radius assertion at all — leaving the vocabulary's own "tab trigger" and "tab list" as the only named roles governed nowhere. They had merely changed file; re-pointed.
• Vocabulary said checkbox → pill 999px, while every checkbox renders rounded-[var(--radius-control)]. The code is right (a fully round checkbox is a radio); the vocabulary was wrong, and because Checkbox is absent from the table nothing ever caught it.
• .enabledEmptyChip was pinned to control by reading its class name. It renders as a full-width two-line card with 16px padding — surface now, matching its twin .settingsWechatQrState.

Dead by construction

input-group's **:[textarea_button]:rounded-[calc(var(--radius-sm)-1px)] compiles to :is(… *):is(textarea button) — a <button> inside a <textarea>, which the HTML content model forbids. Not merely unused, unmatchable. Removed.

Deliberately not changed

• Toggle / ToggleGroup look dead from the app's side (no JSX call sites) but are design-system primitives with a dedicated story, pinned by storybook-baseline-contract. Entries stay.
• The tier values (6/8/12/999). The audit raised real questions — one control token spans a 16px Kbd to a 36px Input, a 2.25× swing in roundness, and 6-vs-8 is below the perceptual threshold as a global semantic distinction (it only does work in concentric nesting). But changing them moves the whole app's surface: a design decision, not a defect fix. Left for a separate call.

Gate

lint · format:check · build · typecheck · knip (both workspaces) · check-console · check-dead-css — all clean, plus 2879 main-process tests passing.