craft: add laws-of-ux guidance

Adds the laws-of-ux craft guidance for generated UI work.

craft/README.md

@@ -69,6 +69,7 @@ A purely behavioral craft file (state-coverage, animation-discipline) is guidanc
 | `accessibility-baseline.md` | `accessibility-baseline` | Any skill that ships interactive UI: dashboards, forms, mobile flows, anything with focus/labels/keyboard paths |
 | `rtl-and-bidi.md` | `rtl-and-bidi` | Any skill that ships localized text or layout: blogs, docs, financial tables, mobile apps, anything that may render Arabic / Hebrew / Persian |
 | `form-validation.md` | `form-validation` | Any skill whose primary artifact contains an interactive form: lead capture, sign-in, signup, settings, multi-step intake |
+| `laws-of-ux.md` | `laws-of-ux` | Any skill whose composition decisions hit named cognitive limits: pricing pages (Hick's, Choice Overload, Von Restorff), dashboards (Pareto, Selective Attention, Working Memory), onboarding (Goal-Gradient, Zeigarnik, Peak-End), modals (Fitts's, Tesler's). Sibling axis to the rendering-rule files above — covers what to compose, not how to render. |
 
 **Partial-stateful skills.** A skill that's mostly static but contains an embedded form, data table, or query surface should opt in. State-coverage rules apply to the stateful component, not the whole page.
 

craft/laws-of-ux.md

@@ -0,0 +1,297 @@
+# Laws of UX craft rules
+
+Universal cognitive, perceptual, and behavioral heuristics that decide
+what a UI composes — how many pricing tiers fit on a screen, where a
+primary action anchors in scanning order, when a progress indicator
+earns its place, why a settings list needs grouping. The active
+`DESIGN.md` decides brand visual language; the existing craft files
+decide rendering rules (color, typography, motion, states, ARIA, RTL,
+forms); this file decides composition rules grounded in named research.
+
+> Distilled from primary sources: Hick (1952) + Hyman (1953), Miller
+> (1956) for chunking / `7±2` channel capacity, Cowan (2001) for the
+> modern ~4 working-memory bound, Fitts (1954), Wertheimer (1923) for
+> proximity / similarity / Prägnanz, Palmer (1992) for Common Region,
+> Palmer & Rock (1994) for Uniform Connectedness, Kahneman /
+> Fredrickson / Schreiber / Redelmeier (1993) for Peak-End, Zeigarnik
+> (1927), Csíkszentmihályi (1975), Hull (1932), von Restorff (1933),
+> Broadbent (1958), Sweller (1988), Postel (RFC 760, 1980), Carroll &
+> Rosson (1987), Tversky & Kahneman (1974) for Anchoring, Kurosu &
+> Kashimura (1995), Iyengar & Lepper (2000), Toffler (1970), Pareto
+> (c.1906) / Juran (*Quality Control Handbook*, 1951), Ebbinghaus
+> (1885), Ockham (14th c.), Tesler at Apple (1980s), Nielsen (2000),
+> Norman *POET* (1988), Parkinson (1955).
+
+## Prior art and scope
+
+Existing public catalogs of UX heuristics (Yablonski's lawsofux.com,
+NN/g's 10 usability heuristics, Material 3 motion + interaction
+guidance, Apple HIG, Baymard Institute checkout research) inventory the
+laws but rarely tie each one to a concrete code-gen directive. This
+file does the translation: every entry ends with one actionable move
+for an HTML / Tailwind / React-emitting agent. Sibling craft files
+(`accessibility-baseline.md`, `state-coverage.md`, `typography.md`,
+`anti-ai-slop.md`, `color.md`, `animation-discipline.md`,
+`form-validation.md`) own the auto-checked rules; this file names the
+underlying law and surfaces the folklore. Out of scope: Weber-Fechner
+psychophysics and Signal Detection Theory — both apply to UI but the
+prompt-emission directives are too narrow to earn a slot here. Add
+later if a skill needs them.
+
+The rules below are guidance, not auto-checked. Reviewers and the agent
+apply them; the linter does not. Where a law has a sibling rule already
+auto-checked elsewhere — touch-target floor in
+`accessibility-baseline.md`, the 300 ms / 2 s / 10 s / 30 s / 60 s
+loading thresholds in `state-coverage.md`, ALL CAPS letter-spacing in
+`typography.md`, the indigo / gradient / emoji-icon list in
+`anti-ai-slop.md` — the entry below cross-references rather than
+duplicates.
+
+## Perception and visual grouping
+
+Five Gestalt laws plus three attention-and-recognition laws govern how
+the eye groups elements before the brain reads them.
+
+- **Law of Proximity** (Wertheimer, 1923). Objects near each other read
+  as a group. Cheapest grouping signal — cheaper than borders or shared
+  color. Apply variable vertical rhythm: 8–12 px within a group,
+  32–48 px between groups. Uniform spacing reads as nothing being
+  grouped.
+- **Law of Similarity** (Wertheimer, 1923). Visually similar elements
+  read as a group. Equivalent affordances must share treatment — every
+  list row identical class set, every secondary button identical, every
+  destructive action identical. Visible deviation is reserved for the
+  one item meant to draw attention (the recommended pricing tier, the
+  selected nav item).
+- **Law of Common Region** (Palmer, 1992). A shared bounded area binds
+  enclosed elements. Use enclosure when proximity is not enough — and
+  reserve it. Concrete numbers: padding ≥16 px inside the region,
+  distinct surface (border + tinted background, or card chrome at
+  ≥1 px hairline). A page where every section is bordered destroys the
+  signal.
+- **Law of Prägnanz / Good Figure** (Wertheimer, 1923). The eye
+  resolves complex layouts into the simplest underlying form. Designs
+  that align with a clear underlying grid (12-column, F-pattern,
+  4-quadrant) feel inevitable; ornate breaks that add nothing semantic
+  feel arbitrary.
+- **Law of Uniform Connectedness** (Palmer & Rock, 1994). The
+  strongest grouping signal in the Gestalt hierarchy: connected lines,
+  shared toolbars, or bracketing containers tie items together more
+  strongly than proximity or similarity. Use for wizard steps,
+  comparison sets, and explicit navigation flows.
+- **Selective Attention** (Broadbent, *Perception and Communication*,
+  1958). Cognitive bandwidth is finite. Users filter aggressively and
+  ignore anything that looks irrelevant to their goal — banner blindness
+  comes from this. Reserve the strongest visual contrast for the single
+  goal-relevant action; let supporting content recede in weight.
+- **Von Restorff Effect** (von Restorff, 1933). The item that differs
+  from a uniform field is the one most likely to be remembered. Make
+  the recommended pricing tier, the active nav item, the warning state
+  visually distinct. Pair contrast with a non-color signal (icon, text
+  label, position) — `accessibility-baseline.md` rules out color-alone
+  signaling.
+- **Aesthetic-Usability Effect** (Kurosu & Kashimura, Hitachi Design
+  Center, 1995). Visual polish biases perceived usability. Refined
+  typography, generous whitespace, and a calm palette earn the benefit
+  of the doubt for minor friction. Never substitutes for measurable
+  usability or for `state-coverage.md`'s required-states rule.
+
+## Decision-making
+
+Six laws govern how fast and how well users decide when an interface
+offers a choice.
+
+- **Hick's Law** (Hick, 1952; Hyman, 1953 replication). Decision time
+  grows roughly log(n+1) with the number of equivalent options. Cap any
+  single decision-screen to 3–5 visible primary options; collapse the
+  rest behind a "More" / progressive disclosure pattern; visually
+  distinguish the recommended choice. Aggressive truncation that hides
+  the path forward is the opposite failure mode — surface the full
+  option set, just don't render every option at the same visual weight.
+- **Choice Overload** (Iyengar & Lepper, *Journal of Personality and
+  Social Psychology*, 2000; framing dates to Toffler, *Future Shock*,
+  1970). Too many roughly-equivalent options stall or abandon the
+  decision. Pricing pages: 3–4 tiers, exactly one marked recommended.
+  Product grids: 6–9 hero cards above the fold. Settings panels: ≤5
+  named groups. Never emit a flat wall of equivalents.
+- **Anchoring** (Tversky & Kahneman, *Science* 185:1124–1131, 1974).
+  The first number a user sees re-weights every subsequent number.
+  Place the recommended pricing tier where it anchors the comparison;
+  render yearly-billing savings as concrete dollar deltas, not just
+  percentage badges; pre-select the safer default in radio groups.
+  Visual weight matches intended decision weight.
+- **Pareto Principle / 80-20** (Pareto, c.1906; Juran, *Quality Control
+  Handbook*, 1951 — popularized the management-application framing). A
+  small share of features drives most of the value. Identify the 2–3 actions
+  that drive the dominant journey for the target persona; emphasize
+  those visually; demote the long tail to overflow menus, footer
+  surfaces, or settings.
+- **Tesler's Law / Conservation of Complexity** (Tesler, Apple, 1980s).
+  Every product has an irreducible amount of complexity. The design
+  choice is *where* it lives — engineering team, interface, user — not
+  whether to eliminate it. When complexity reaches the user, surface
+  contextual guidance (tooltips, smart defaults, inline empty-state
+  coaching, progressive disclosure) at the exact step where it
+  surfaces. Hiding it is not the same as removing it.
+- **Occam's Razor** (Ockham, 14th c.). Among options that explain the
+  data equally well, prefer the one with the fewest assumptions. Specify
+  a minimal element inventory; forbid decorative chrome that doesn't
+  serve a stated user task. The law constrains assumptions, not feature
+  count — a "minimum viable" framing misreads it.
+
+## Memory and learning
+
+Five laws cover how working memory handles information density and
+what the user retains afterward.
+
+- **Miller's Law and Chunking** (Miller, *The Magical Number Seven,
+  Plus or Minus Two*, *Psychological Review*, 1956 — channel capacity /
+  `7±2` and chunking; Cowan, *Behavioral and Brain Sciences* 24:1, 2001
+  for the modern ~4-item working-memory bound). Working memory holds
+  about four items reliably and up to seven for short-term recall. Each
+  slot can hold a *larger familiar unit*, constrained by the user's
+  domain knowledge — chunking does not let you pack arbitrary content
+  into a single slot. Often misread as a rule about menu length;
+  Miller's paper is about chunks. Group related fields with clear
+  section headings, dividers, or card containers. A settings page with
+  sections "Account / Notifications / Privacy / Billing / Danger zone"
+  beats one flat list of 30 toggles.
+- **Working Memory** (Baddeley & Hitch, 1974; lineage to Atkinson &
+  Shiffrin, 1968). Items decay in seconds without rehearsal. Recognition
+  beats recall: persisting prior context across screens, marking visited
+  elements, and surfacing comparison views beats forcing the user to
+  memorize. On dashboards specifically: sticky filter chips, last-N
+  selections persisted, breadcrumbs that include applied filters.
+- **Serial Position Effect** (Ebbinghaus, *Über das Gedächtnis*, 1885).
+  Recall favors the extremes — primacy at the start, recency at the
+  end — while middle items fade. Anchor the most important nav items at
+  the leftmost and rightmost positions of a horizontal menu; cluster
+  utilities in the middle.
+- **Peak-End Rule** (Kahneman, Fredrickson, Schreiber, Redelmeier,
+  *Psychological Science*, 1993). Memory of an experience is dominated
+  by the emotional peak and the ending, not the average. Stage a
+  high-effort celebratory success state; let intermediate steps stay
+  calm. Mediocre middles matter less than a strong close. The peak
+  belongs at the *end* of a flow, not as arbitrary mid-flow motion —
+  `animation-discipline.md` rejects motion that performs (rather than
+  confirms) a state change.
+- **Zeigarnik Effect** (Zeigarnik, *Über das Behalten erledigter und
+  unerledigter Handlungen*, 1927). Uncompleted tasks create cognitive
+  tension that pulls the user back. Visible progress ("3 of 5 steps",
+  greyed-out next sections) converts that tension into completion
+  pressure. Reserve for genuinely beneficial flows like onboarding;
+  applying the same lever to streaks, daily-quest counters, or notification-
+  reduction nags is a dark pattern.
+
+## Interaction and motor
+
+Five laws cover how fast and how accurately users can act on the UI.
+
+- **Fitts's Law** (Fitts, *Journal of Experimental Psychology*, 1954).
+  Time to acquire a target depends on its distance and size — bigger
+  and closer is faster. Spacing between adjacent hit zones matters as
+  much as size. Pair with `accessibility-baseline.md`'s 24 × 24 CSS px
+  AA touch-target floor; on mobile, place high-frequency controls in
+  the natural thumb arc.
+- **Doherty Threshold** (Doherty & Thadani, *IBM Systems Journal*,
+  1982). Sub-second feedback keeps users in flow; latency above ~1 s
+  breaks attention. The implementable directive lives in
+  `state-coverage.md`'s loading-threshold table (no indicator under
+  300 ms; skeleton 300 ms – 2 s; labelled spinner 2 – 10 s; determinate
+  bar with cancel 10 – 60 s; stop and offer error/retry past 60 s).
+  This entry exists to name the underlying law and flag its folklore
+  (the 400 ms number doesn't appear in the 1982 paper — see
+  `animation-discipline.md` for the 400 ms folklore trace).
+- **Flow** (Csíkszentmihályi, *Beyond Boredom and Anxiety*, 1975). Flow
+  sits in the balance between challenge and skill — too hard breeds
+  frustration, too easy breeds boredom. Continuous feedback and a clear
+  sense of control keep the user inside the state. System friction and
+  latency are the fastest ways to break it.
+- **Goal-Gradient Effect** (Hull, *Psychological Review*, 1932; Kivetz,
+  Urminsky, Zheng, 2006 for the punch-card replication). Motivation to
+  finish rises as the goal gets closer. Multi-step flows render with a
+  prominent progress indicator that reflects *real* endowed progress —
+  show completed prerequisites when they truly exist (saved profile,
+  imported team, prior survey answer). When no real prerequisite
+  exists, render the current step honestly as `1 of N` with the
+  empty/current-step state clearly marked. Hull's hypothesis is
+  descriptive; treating it as license for fabricated progress, streak
+  dark patterns, or loyalty-program quota inflation is a misread.
+- **Postel's Law / Robustness Principle** (Postel, RFC 760, 1980). "Be
+  liberal in what you accept, conservative in what you send." Take
+  input in whatever shape users naturally give it (phone numbers with
+  or without dashes, dates in mixed formats, percentages with or
+  without `%`); normalize internally to a canonical form; emit one
+  consistent format on output. The error-timing and ARIA-wiring half
+  lives in `form-validation.md`; the input-tolerance half is the
+  directive above. RFC 9413 (Thomson, IAB, 2023; built on the earlier
+  `draft-iab-protocol-maintenance`) retracts the maxim for protocol
+  design citing security surface; the UX-input application stands.
+
+## Behavior and expectation
+
+Five laws cover what users predict and how that prediction interacts
+with the rendered surface.
+
+- **Jakob's Law** (Nielsen, Nielsen Norman Group, 2000). Users spend
+  most of their time on other sites and expect yours to work the same.
+  Reuse category convention — nav placement, cart icon, settings gear,
+  primary CTA in the upper right of a SaaS landing — so the user spends
+  zero cycles relearning interaction grammar. Novelty must earn its
+  keep against the convention's ROI; "innovate everywhere" is the
+  opposite failure mode.
+- **Mental Model** (Craik, *The Nature of Explanation*, 1943; Norman,
+  *POET / The Psychology of Everyday Things*, 1988). Every user
+  arrives with a prior built from competitor products and the physical
+  world. When the prediction holds, the product feels intuitive; when
+  it breaks, friction shows up as confusion, not curiosity. When the
+  brief names a reference product, anchor explicitly — capture the
+  reference in the prompt and the agent inherits a transferable
+  interaction grammar.
+- **Paradox of the Active User** (Carroll & Rosson, in *Interfacing
+  Thought: Cognitive Aspects of Human-Computer Interaction*, MIT Press,
+  1987, pp. 80–111). Users skip the manual and start using the
+  software immediately, even when reading it would speed them up. Bake
+  guidance into the surface itself — empty-state coaching, inline
+  tooltips, contextual hints — at the action point.
+- **Parkinson's Law** (Parkinson, *The Economist*, 1955). Work expands
+  to fill the time allotted to it. Loose interfaces let users dawdle;
+  cut friction and pre-fill what you can — autofill, smart defaults,
+  saved state — so a checkout finishes faster than the user expected.
+  Beating anticipated duration becomes the felt win.
+- **Cognitive Load** (Sweller, *Cognitive Science*, 1988). Total
+  mental effort splits into intrinsic (the task's inherent difficulty)
+  and extraneous (poor layout, jargon, inconsistent patterns, visual
+  noise). Designers can't reduce intrinsic load; they own extraneous
+  fully. The visual-restraint directives (single accent in `color.md`,
+  three-weight typography rhythm in `typography.md`, P0 anti-default
+  list in `anti-ai-slop.md`) already constrain extraneous load; this
+  entry exists to name the cognitive cost the sibling rules reduce.
+
+## Common mistakes (lint these)
+
+Folklore corrections that don't survive a primary-source check, in the
+same vein as the busts already documented in `animation-discipline.md`
+and `accessibility-baseline.md`. The first three are attribution
+corrections (year / venue / institution) the body entries already
+applied — restated here so a reviewer reading just this section sees
+them. The remainder are folklore not addressed in the body.
+
+- "Anchoring effect = Tversky & Kahneman 1972." Wrong year. The
+  *Science* paper introducing the anchoring framing is 1974; the 1972
+  paper is "Subjective probability: A judgment of representativeness"
+  (different work).
+- "Tesler's Law was developed at Xerox PARC." Tesler left PARC for
+  Apple in 1980; the Conservation-of-Complexity formulation traces to
+  his Apple years.
+- "Paradox of the Active User was a CACM article." It's a chapter in
+  Carroll's *Interfacing Thought* (MIT Press, 1987), not CACM.
+- "Selective Attention = solved by red dots and badges." Repeated
+  attention-grabbers train banner blindness. Reserve the strongest
+  contrast for one goal-relevant action per surface.
+- "Fitts's Law alone is enough for touch targets." Fitts gives the
+  speed-accuracy tradeoff. WCAG 2.2 SC 2.5.8 sets the AA floor at
+  24 × 24 CSS px (`accessibility-baseline.md`); iOS HIG suggests
+  44 × 44 pt; Material 3 suggests 48 × 48 dp. Fitts plus the
+  platform floor — never just Fitts.
+

skills/dashboard/SKILL.md

@@ -23,7 +23,7 @@ od:
     requires: true
     sections: [color, typography, layout, components]
   craft:
-    requires: [state-coverage, accessibility-baseline]
+    requires: [state-coverage, accessibility-baseline, laws-of-ux]
 ---
 
 # Dashboard Skill

skills/kanban-board/SKILL.md

@@ -23,7 +23,7 @@ od:
     requires: true
     sections: [color, typography, layout, components]
   craft:
-    requires: [state-coverage]
+    requires: [state-coverage, laws-of-ux]
   example_prompt: "Make me a kanban board for a 5-person growth squad mid-sprint — backlog, doing, review, done."
 ---
 

skills/mobile-onboarding/SKILL.md

@@ -24,7 +24,7 @@ od:
     requires: true
     sections: [color, typography, layout, components]
   craft:
-    requires: [state-coverage, animation-discipline, accessibility-baseline, form-validation]
+    requires: [state-coverage, animation-discipline, accessibility-baseline, form-validation, laws-of-ux]
   example_prompt: "Design a 3-screen mobile onboarding flow for a meditation app — welcome, value props, sign-in."
 ---
 

skills/pricing-page/SKILL.md

@@ -22,6 +22,8 @@ od:
   design_system:
     requires: true
     sections: [color, typography, layout, components]
+  craft:
+    requires: [laws-of-ux]
 ---
 
 # Pricing Page Skill

skills/saas-landing/SKILL.md

@@ -20,7 +20,7 @@ od:
     requires: true
     sections: [color, typography, layout, components]
   craft:
-    requires: [typography, color, anti-ai-slop]
+    requires: [typography, color, anti-ai-slop, laws-of-ux]
   inputs:
     - name: product_name
       type: string