Design Principles
Section titled “Design Principles”Target-agnostic design principles. These bind on every deliverable — website, app or mini-app, book/booklet/pamphlet, report, deck. How each one cashes out per medium is in Targets/.
1. F.A.S.T. — the primary constraint
Section titled “1. F.A.S.T. — the primary constraint”SSOT for the definition: Core/Misc/Glossary.
Fast (respects time), Adaptable (progress beyond basics only where you value more), Simple (easy to understand and implement), Tailored (personalized to your specifics).
F.A.S.T. outranks conventional design convention. Where a design norm and F.A.S.T. conflict, F.A.S.T. wins. This is a CEO directive, not a preference.
Operationally, for design:
| Letter | What it demands of a deliverable |
|---|---|
| Fast | Time-to-first-value is the metric. Perceived speed counts — a skeleton beats a spinner; a rendered default beats an empty form. |
| Adaptable | Start simple and minimal; progress further only where the person values more. This is progressive disclosure, and it is why §2 and §3 below exist. |
| Simple | Understandable and implementable without instruction. Fewer inputs, fewer metrics, fewer choices — not smaller type. |
| Tailored | Defaults personalized to the person’s actual situation, ideally without them supplying it (§6). |
“Start simple, minimal, then progressive” is F.A.S.T.’s A. It is not a separate principle — treating it as one splits a single idea across two homes.
Note on the “A”: F.A.S.T.’s A is Adaptable in the progressive-disclosure sense above (Talbot, ratified 2026-08-29). A distinct behavioural idea — firing an intervention at an individual’s threshold crossing rather than a population calendar event — is discussed at Core/Processes/Behavioural-Solutions.md §6 under the word “Adaptive”. That is a timing principle, not this one, and it is not F.A.S.T.’s A.
2. 80/20 BIG Rocks Focus, EVERYWHERE
Section titled “2. 80/20 BIG Rocks Focus, EVERYWHERE”- Focus on most important elements first
- Applies to EVERYTHING
- Inputs (One/two core)
- Analysis/Results (One/two core), then “More”
- Concepts/education
- Progressively add more only if needed/valued
Originally written for SD App development; it generalizes to every target without change.
A note on scope
Section titled “A note on scope”Sections 1–3 here are genuinely target-agnostic. The input/output mechanics that used to sit at §§3–4 — the one-or-two-core-inputs rule, “See all”, and Highest Impact Analysis — are app-and-calculator guidelines, not global ones, and now live in Design — Apps where they belong (Talbot, 2026-08-29). A page or a pamphlet has no inputs to simplify; an app does.
3. Personalized / Tailored
Section titled “3. Personalized / Tailored”The T in F.A.S.T. The devices available, cheapest first:
- Predefined User Profiles — one click stands in for many inputs (e.g. Middle-income / High-income). The primary device.
- Inferred context — country/region determined automatically by browser rather than asked.
- Progressive personalization — take what is volunteered as the person goes deeper; never gate the first result on it.
- Personalization settings stored/retrieved automatically (respecting privacy regulations), to also enhance Fast, Adaptable. Local storage default. Some apps will also store settings in backend.
4. Accessibility floor
Section titled “4. Accessibility floor”WCAG AA is the floor on every visual deliverable. Not restated here — the SSOT is GlobalDevRules §3.7 (Accessibility): ARIA, semantic HTML, keyboard navigation, WCAG AA contrast, screen-reader testing.
5. Voice
Section titled “5. Voice”Voice is a design constraint, not a separate discipline — the words are part of the interface. Schema and per-brand router: Voice.
6. Provenance
Section titled “6. Provenance”§2 and the seed of §3 — plus the two input/output sections now in Design — Apps — are lifted verbatim from SDC/_WorkingOn/Projects/SD-App/archive/DESIGN.md, whose taxation half was folded into the monorepo repo on 2026-08-28 (commit c3e497c) while its UI/UX half was left without a home. That gap was recorded at SDC/_WorkingOn/Projects/SD-App/PORTAL.md and was blocking LevPro mini-app UI work per SDC/Logs/Dev/2026-08-28_LevPro-sd-math-M5-M6-RRSP.md. This file closes it.
The archive copy stays where it is as frozen prior art. This file is the live SSOT.
7. Time-series charts: “View: All / 20 years”
Section titled “7. Time-series charts: “View: All / 20 years””Every interactive time-series chart gets a View: All / 20 years control (Talbot, 2026-09-24). This is F.A.S.T.’s Adaptable principle applied to charts: the full history is the default, and a closer look is one click away.
- All shows the whole period with data.
- 20 years shows one 20-year window, with a start-year slider to move it.
- Growth-of-$1 charts rebase to $1 at the window start. Otherwise a window cut from a 1926 curve compares nothing.
- Log axes label 1-2-5 steps, so a short window still has readable ticks.
- Reference implementation:
~/projects/cape-timing/report/base.js(RUI.tsChart).