JBSYS

Case study / v0.6.0 released local-first prototype

Neutro

A local-first, user-controlled interface adaptation prototype with transparent profiles and explainable changes.

Repository ↗
Neutro verified interface

Problem

Interfaces often hide accessibility settings across disconnected controls or infer needs without giving the user a clear explanation and reset path.

Target user

People who want direct control over presentation preferences in one browser.

Solution

A deterministic adaptation studio for typography, contrast, motion, sensory load, layout, and focus assistance with live preview, explanations, persistence, and reset.

Personal contribution

Refocused the product around explicit user choice; implemented the preference engine, provider, accessible workflow, persistence recovery, tests, performance split, documentation, and narrated release evidence.

Architecture

Boundaries before buzzwords.

  1. Pure preset, normalization, and explanation rules
  2. React provider mapping state to CSS variables and document attributes
  3. Versioned local browser persistence
  4. Route-split optional reading, replay, and camera labs

Main workflow

State moves with a reason.

  1. 01

    Choose a transparent starting profile

  2. 02

    Override any presentation dimension

  3. 03

    Inspect the live preview and explanations

  4. 04

    Reload to confirm local persistence

  5. 05

    Reset completely to Balanced

Technical decisions

The trade-offs that define the system.

  • Manual changes always become an explicit Custom profile
  • System reduced motion is never overridden by forced motion
  • Camera heuristics cannot change adaptation preferences or trigger automatic intervention
  • Optional labs load separately from the primary workflow

Difficult engineering challenge

The product needed to make adaptation immediately useful while keeping every transformation user-controlled, reversible, explainable, and free of unsupported medical inference.

Verification

Evidence and boundaries.

Testing

  • 6 deterministic Vitest cases
  • Desktop persistence/reset Playwright workflow
  • 390×844 overflow and keyboard-focus check
  • Canonical and legacy lint/build CI
  • 0 known npm vulnerabilities

Security and privacy

  • Preferences remain in versioned browser storage
  • Camera and replay are off by default and require explicit user action

Known limitations

  • Preferences do not sync across browsers or devices
  • No clinical validation, health outcome, or cross-platform desktop claim

Focused future work

  • Add automated accessibility scanning and broader assistive-technology/browser evidence

Verified demonstration

Rendered product behavior.

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