System · Atlas

UX

Operator experience — states, heuristics, disclosure, empty/error.

ux.md

Meridian — ux.md

User experience — twin pillar with dx.md. Typed: uxLaws in lib/design/experience.ts.
Ranking: influences.md.
Primary absorb: Polaris Pro (meaning, predictable, juicy) + Cursor (keyboard, object-bound) + Fluent (rest→hover→selected, focus stroke) + Linear (quiet chrome) + Vercel (every state) + NN/g heuristics.

0. Twin pillars

UX (this file) and DX (dx.md) outrank cinema polish. If a change improves a screenshot but worsens operator clarity or agent reliability, reject it.

1. North-star UX principles

#	Principle	Source	Meridian rule
1	Obsess over usefulness	Vercel DE	Every control finishes a task
2	Assign meaning	Polaris	Color/icon/depth = role
3	Predictable then juicy	Polaris	Same look → same behavior; press felt
4	Complexity available, not required	Vercel	Progressive disclosure
5	Quiet chrome, loud content	Linear	Brand tint limited in chrome
6	Object-bound AI	Cursor app	No floating chatbot
7	Focus ≠ fill	Fluent color/interaction	Ring/stroke for keyboard
8	Visibility of status	NN/g #1	Loading + agent activity always visible
9	Error prevention & recovery	NN/g #5 · #9	Specific copy + retry; confirm destructive
10	Recognition over recall	NN/g #6	Show labels / kbd hints; don’t rely on memory

NN/g → Meridian map (compressed)

Heuristic	Encode
1 Status	Skeletons, `bg-activity-*`, mono tool names
3 Control & freedom	Escape, undo-friendly defaults, non-modal where possible
4 Consistency	Closed radii / states / typeset presets
5–9 Errors	`emptyAndErrorOwned`; never silent failure
7 Flexibility	Keyboard power + pointer defaults (`data-surface`)
8 Minimalist	Quiet chrome; one idea per cinema frame
10 Help	`typesetClass("docs")` drawers — not walls of tip text

Agent UI disclosure (Nielsen on progressive disclosure)

Level 1 — outcome + decision-critical ask
Level 2 — activity / tool trace (one click)
Never narrate every tool call in the primary pane — and never hide the ledger entirely.

2. Interaction state model (Fluent + Polaris)

rest → hover → pressed → selected
                 ↘ focus-visible (parallel track)

State	Visual	Notes
Rest	Neutral surface	No brand border by default
Hover	`bg-muted/30–40`	Quiet (Polaris: unobtrusive)
Pressed	Slightly stronger muted / scale micro	Juicy but short
Selected	`bg-brand/10`	Not a thick brand border
Focus-visible	`ring-ring` / thicker stroke	Fluent: focus changes container stroke, not only fill
Disabled	Reduced opacity + `pointer-events-none`	Still contrast-safe where needed
Danger	`bg-destructive/10` + destructive text	Never brand

Rest → hover → selected (Fluent)

Controls generally get darker through interaction on paper; selected uses brand wash. Dark mode follows token aliases — never hardcode branches.

3. Control affordances

Control	Afford	Anti
Button primary	Brand fill, clear label	Neon, chevron garnish
Button ghost	Transparent + hover muted	Brand border chrome
Input	`rounded-lg`, thin border or edge	Shadow-md wells
Row / nav item	Full-row hit target, h-7–h-9	Tiny icon-only without label (unless toolbar)
Checkbox / toggle	Instant check feedback	Novelty bounce loops
Menu item	`rounded-lg`, focus = accent wash	Nested hover traps

4. Keyboard & command

Cursor / Linear operators expect:

Shortcut pattern	UX
`⌘K` / command palette	Jump anywhere
Arrow + Enter in lists	Move selection
`⌘↵` in agent composer	Submit bound to object
Tab / Shift+Tab	Visible focus rings always

Show kbd hints in mono near search — never as the only discoverability path.

5. Information architecture patterns

Indexes (Polaris density + Linear rows)

Filter/search chrome (compact)
Dense table/list
Selection opens detail or agent rail
Empty / error / loading owned (Vercel)

Detail

Object title + mono ID
Primary actions
Properties
Optional AI rail bound to this ID

Marketing film

One idea per svh stage — see cinema laws. CTAs: one primary + optional secondary; no chevrons.

6. Feedback & messaging

Kind	Treatment
Success	Brand-linked success token + short copy
Warning	`warning` semantic — not brand
Destructive	Confirm; `destructive` colors
Agent activity	`bg-activity-*` + mono tool name
Toast / inline	Prefer inline near object; avoid modal spam

7. Progressive disclosure

Default visible	Reveal when needed
Core nav + index	Agent rail
Primary CTA	Secondary tools
Paper application	Theater marketing
Summary meta	Full provenance timeline

OpenAI-style lesson: product is hero; complexity waits (influences §9).

8. Empty, loading, error (mandatory)

Every index/detail must define:

State	Minimum
Loading	Skeleton or quiet mono “Loading…” — no layout jump
Empty	One sentence + one action
Error	Specific message + retry
No permission	Clear next step

9. Touch vs pointer

Lane	Target	Notes
`mobile`	≥44×44	Fluent / Apple HIG aligned
`application`	32px controls	Dense but clickable
`desktop`	28px chrome OK	Keyboard primary

10. Accessibility UX

Never color-only meaning (Fluent + WCAG)
Body text ≥ 4.5:1; large ≥ 3:1 (check:contrast)
Theater stages lift --brand via data-tone="theater"
prefers-reduced-motion honored (see animations.md)
Labels on icon buttons (aria-label)

11. Anti-patterns

Ban	Why
Floating chatbot	Unbound AI
Brand borders on every selected thing	Noise
Hover-only critical actions	Pointer exclusive
Scroll-jacking tutorials	Cinema ban
Status color as decoration	Polaris meaning
Infinite onboarding modals	Usefulness fails

12. Proofs

Proof	Where
Resource empty / loading / error	Workbench + Composer demos
Outcome → activity trace	Agent rails (`data-slot="agent-outcome"` / `agent-trace`)
Keyboard parity	`/meridian/theme#keyboard` · `/meridian/surfaces#keyboard`

13. Agent checklist

States: rest/hover/focus/selected/disabled/empty/loading/error
Selected = brand wash; focus = ring
AI: outcome first, trace one click away
Keyboard path exists
meridian-a11y + contrast + experience gates

Sources

Raw