# Decision: `indicator_mode` — a colour-optional rendering mode for UI signals

**Date:** 2026-08-31
**Status:** active

## Context

Several UI signals were encoded by hue alone and unreadable with a colour-vision deficiency:

- `price_quality` (0–9) as a red→yellow→green gradient — a dot in the configurator search
  dropdown and inline before `lot_name`, a coloured number in the pricelist "Качество" column,
  a full-row background tint on the "Ценообразование" tab;
- the amber `world`-fallback price cell tint
  ([2026-07-10-world-pricelist-fallback.md](2026-07-10-world-pricelist-fallback.md));
- the red "contaminated total" in the pricing footer
  ([2026-07-24-pricing-total-world-share.md](2026-07-24-pricing-total-world-share.md)).

The bible has no dedicated accessibility contract, but `table-management` §Icon Semantics,
`controls-selection` §Buttons, `go-code-style` §Business Logic Placement and `build-version-display`
say the same thing: meaning is never carried by one ambiguous channel — back it with
shape / number / explicit `title`+`aria-label`, and keep the indicator visually subordinate.

## Decision

One per-client preference, **`app_settings.indicator_mode`** = `color` (default) | `accessible`,
set on `/setup` ("Настройки") via `GET`/`PUT /api/settings/ui` (`internal/handlers/settings.go`)
— no restart. Deliberately named for the concern (how indicators are rendered), not for the
current widget, so future colour-only signals attach to the same switch.

`internal/handlers/web.go` `render()` and `internal/handlers/setup.go` inject the mode for every
page; `base.html` publishes it as `window.QF_INDICATOR_MODE`. `web/static/price-quality.js` is
still the single source of the price-quality scale and branches on the mode internally, so its
call sites do not change.

In `accessible` mode:

- `price_quality` renders as a **5-step signal-strength meter** (`priceQualityLevel` =
  `min(4, floor(score/2))` → `0-1 / 2-3 / 4-5 / 6-7 / 8-9`), five bars in one neutral hue, each
  instance carrying `title`/`aria-label` = `Качество цены: N/9`. `qualityDotHtml` and
  `qualityBadgeHtml` return the meter;
- `qualityRowStyle` returns `''` — the pricing tab instead shows the meter in a narrow leading
  column (conditional `<th>` / `colspan` in `index.html`, per-sub-row `<td>`);
- the `world`-fallback amber class is dropped for a `W` superscript text marker on the price
  (text, not a colour class — `applyCustomPrice`'s colour-stripping regex is a non-issue);
- `_setPricingTotal` drops `text-red-600` for a leading `⚠` glyph, on the same trigger as the
  red (`worldShare > 0`). The hover popup — including the "prices for N of M positions" coverage
  line — is unchanged in both modes; per 2026-07-24 there is still no colour-coded coverage-only
  signal, and `accessible` mode does not add one.

`color` mode is byte-for-byte the previous behaviour.

## Consequences

- Default unchanged; nothing moves until a user opts in on `/setup`.
- `web/static/price-quality.js` stays the only place that knows the 0–9 scale. Any new
  colour-coded quality/price signal adds a branch there keyed on `isAccessible()`, never a local
  reimplementation, and its `accessible` form must be shape/text, not another hue.
- The pricing-tab tables have a mode-dependent column count (8 / 9). `index.html` guards the
  `<th>`, the empty-state `colspan`, the `tfoot` "Итого:" `colspan` and the JS row template on
  `ACCESSIBLE_MODE` / `{{ eq .IndicatorMode "accessible" }}`. CSV export is untouched — it reads
  `data-*` row attributes, not cell positions.
- New routes `GET`/`PUT /api/settings/ui`, registered in both the normal and setup-mode route
  sets in `cmd/qfs/main.go`. `render()` nil-guards `localDB` for tests.