INSTRUMENT — design system for AI apps

The problem it solves

You cannot prompt your way out of the AI-app look. More detailed prompts do not fix it, because the convergence is in the model, not in your wording. The only escape is a system with an actual point of view.

The point of view

**Instrumentation.** An oscilloscope, a mixing desk, a flight panel. Flat fills, hairline rules, near-zero radii, graph-paper field, tabular numerics, and exactly **one** hot accent used as a signal — never as decoration.

Deliberately refused: the purple-blue gradient hero, glassmorphism, one uniform radius on everything, emoji as iconography, centered everything, and pill buttons floating in whitespace.

Built outward from AI surfaces

Not a general design system applied to an AI app — designed from these:

• **Streaming text** with a block cursor that steps, in a recessed well, with a capped prose measure so output doesn't run edge-to-edge.
• **Tool calls** as rows on a scope: shared hairlines, state carried in the left rail, expandable payloads, failures auto-open.
• **Reasoning traces** collapsed to a scope sparkline, expandable to prose.
• **Approval gates** with severity — and **hold-to-confirm on irreversible actions**, because approval fatigue is real and a click is one motor action.
• **A cost meter**: multimeter readout plus a notched gauge.
• **The states everyone forgets**: empty, loading, degraded, refused.

Accessibility asserted in code, not promised in a README

**32 tests.** Every ink/background pair is contrast-checked in *both* themes. State is never conveyed by color alone — every state carries a mono chip label plus a distinct edge or hatch, legible with no color perception at all. `prefers-reduced-motion` collapses all timing including the press and hold gestures. No external font CDNs, so it works under a strict CSP.

The suite earned its keep immediately: it caught **two contrast failures in the original token set** (4.46 and 4.31 against a 4.5 floor) that had been *stated* as passing. Tokens were corrected; the claims now match the measurements.

Delivery

Source delivered as a private repository invite within 24 hours of purchase. Single-product commercial license: use and modify in one shipped product; no redistribution or resale of the source.