Accessibility

TermFlow targets terminal apps, where the assistive-technology story is genuinely different from the web: screen readers read the terminal buffer directly, so the practical levers a TUI library has are around colour, motion, and predictable structure.

This page documents the levers TermFlow exposes today.

Colour

• Theme.dark, Theme.light, and Theme.mono ship as built-in palettes.
• Capability detection downgrades cleanly: true-colour → 256 → 16 → 8 → mono. Apps don't need to branch on the terminal — pick a Theme and let the renderer downgrade.
• The NO_COLOR environment variable is honoured: when set, the runtime forces Theme.mono-equivalent rendering regardless of detected capability.

Reduced motion

Some users find ambient animation actively unhelpful — vestibular sensitivity, low-bandwidth sessions, screen-reader environments that re-announce on every frame, or just personal preference. TermFlow exposes a single flag for this: reducedMotion.

Activating reduced motion

Either set the environment variable:

TERMFLOW_REDUCED_MOTION=1

…or set it in the HOCON config:

termflow {
  accessibility {
    reduced-motion = true
  }
}

The env var takes precedence over the config value when set. Truthy values are anything other than "0" or "false" (case-insensitive).

What it affects

The flag is plumbed through RuntimeCtx.config.accessibility.reducedMotion so apps and widgets can read it.

Spinner accepts a reducedMotion: Boolean parameter that, when true, pins the rendered frame to frames(0) regardless of the tick:

import termflow.tui.widgets.Spinner

def view(model: Model)(using ctx: RuntimeCtx[Msg]): VNode =
  Spinner(
    Spinner.Braille,
    frame = model.tick,
    reducedMotion = ctx.config.accessibility.reducedMotion
  )

App-level animation (sine wave demos, custom progress effects, anything driven by Sub.Every purely for cosmetic reasons) should query the flag and either skip rendering or fall back to a static representation.

What it does not affect

• Functional motion — cursor movement, focus changes, scroll position, dialog open/close. Those are part of the app's behaviour, not cosmetic animation.
• Determinate ProgressBar — already non-cycling. Only indeterminate progress indicators count as cosmetic motion, and TermFlow's ProgressBar is determinate-only.

Predictable structure

The Elm-style architecture (update is pure, view is a function of the model) means the rendered frame is fully determined by the model. That's a foundation accessibility tooling can build on — semantic annotations, a linear/announcement renderer, or a screen-reader bridge. Those are post-1.0 work; see the roadmap for current status.