feat: emit the high-contrast tier under a manual contrastLevel

.changeset/quiet-pugs-remember.md

@@ -0,0 +1,29 @@
+---
+'@tenphi/glaze': minor
+---
+
+A manual `contrastLevel` no longer suppresses high-contrast output.
+
+The level now does one thing: it positions the **normal** `light` / `dark`
+variants on the 0–100 slider. The high-contrast tier stays the true
+high-contrast resolution — bit-identical to what `'auto'` resolves — at every
+level, and `modes.highContrast` alone decides whether it is emitted. The two
+compose: a slider raises the baseline while a `prefers-contrast: more` block
+still escalates on top of it.
+
+Most visible in `css()`, which has no `modes` option and always returns four
+strings: at a mid level its `lightContrast` / `darkContrast` blocks now carry
+genuinely escalated values where they previously repeated the normal
+declarations.
+
+Two consequences of the corrected model:
+
+- `contrastLevel: 0` now reproduces `'auto'` output exactly, high-contrast tier
+  included. It no longer implies "no high-contrast tier" — that is
+  `modes.highContrast: false`, still the default.
+- At a global `contrastLevel: 100` the normal variants already *are* the
+  high-contrast ones, so a separate tier would duplicate them: a single
+  light/dark set is emitted, even against an explicit `modes.highContrast: true`.
+
+Also fixes the side-stability probe leaking into the high-contrast passes, which
+made a mid-level high-contrast variant diverge from its `'auto'` counterpart.

AGENTS.md

@@ -37,11 +37,11 @@ glaze/
 | [src/color-token.ts](src/color-token.ts) | Standalone `glaze.color()` tokens. Parses values through `color-value.ts`; owns the structured-input validator, the two factory paths, sparse local config + live resolve, and the JSON-safe export / `glaze.colorFrom` rehydrate round-trip. |
 | [src/color-value.ts](src/color-value.ts) | `GlazeColorValue` parsing + validation: hex (3/6/8), the `rgb()` / `hsl()` / `okhsl()` / `okhst()` / `oklch()` functions, and the four value-object shapes, all normalized to OKHSL by `extractOkhslFromValue`. Split out of `color-token.ts` so the resolver can reach it for a theme color's `from` without closing an import cycle. Leaf module — depends only on the color math. |
 | [src/serialize.ts](src/serialize.ts) | Authoring-export helpers: `GLAZE_EXPORT_VERSION`, `assertExportKind` / `assertExportVersion`, and `isThemeExport` / `isColorTokenExport` / `isPaletteExport` type guards. |
-| [src/resolver.ts](src/resolver.ts) | Four-pass solver (light → light-HC → dark → dark-HC), or two-pass (light → dark) under a manual `contrastLevel`, where the HC slots mirror the normal ones, `passTone` / `passNumber` / `resolveContrastSpec` feed interpolated inputs into the ordinary pass, and a probe solve at the nearer endpoint pins which side of its base a contrast-solved color sits on. Stores canonical tone (`t`) in variants; per-scheme branches for regular, shadow, and mix defs; integrates the contrast solver, and the OKHST tone helpers. `resolveChannels` owns per-scheme hue/saturation (incl. the `darkHue` / `darkSaturation` seed + def overrides, the `darkDesaturation` bypass, and the absolute hue/saturation a `from` color carries in place of the seed factor) and feeds both the emitted variant and the contrast solver. `configForColor` gives a `from` color a local `lightTone: false` so its light variant reproduces the authored value. Converts to/from OKHSL lightness only at the mix/shadow edges. Pre-seeds externally-resolved bases for `glaze.color({ base })`. |
+| [src/resolver.ts](src/resolver.ts) | Four-pass solver (light → light-HC → dark → dark-HC), dropping to two-pass (light → dark) with mirrored HC slots only at `contrastLevel: 100`, where the normal passes already are the HC ones (`hcMirrorsNormal`). Under any other manual level `passTone` / `passNumber` / `resolveContrastSpec` feed interpolated inputs into the two *normal* passes and a probe solve at the nearer endpoint pins which side of its base a contrast-solved color sits on; the HC passes bypass the level and the probe entirely, so the HC tier is bit-identical to `'auto'`. Stores canonical tone (`t`) in variants; per-scheme branches for regular, shadow, and mix defs; integrates the contrast solver, and the OKHST tone helpers. `resolveChannels` owns per-scheme hue/saturation (incl. the `darkHue` / `darkSaturation` seed + def overrides, the `darkDesaturation` bypass, and the absolute hue/saturation a `from` color carries in place of the seed factor) and feeds both the emitted variant and the contrast solver. `configForColor` gives a `from` color a local `lightTone: false` so its light variant reproduces the authored value. Converts to/from OKHSL lightness only at the mix/shadow edges. Pre-seeds externally-resolved bases for `glaze.color({ base })`. |
 | [src/okhst.ts](src/okhst.ts) | The OKHST tone layer. `REF_EPS`, tone↔lightness transfers (`toTone`/`fromTone`, `toneFromY`/`yFromTone`), OKHST↔OKHSL conversions, `variantToOkhsl` (tone→lightness at render), `normalizeToneWindow` (`[lo,hi]` / `{lo,hi,eps}` / `false` → `{lo,hi,eps}`), `mapToneForScheme` (scheme inversion + window remap, HC bypass), `mapSaturationDark` (the `darkDesaturation` reducer the resolver skips when a dark saturation is authored), and `schemeToneRange` for the solver. `activeWindow` owns the HC window bypass and its continuous form under `contrastLevel`. Only tone adapts here — hue/saturation are the resolver's business. |
-| [src/contrast-solver.ts](src/contrast-solver.ts) | Tone-based binary-search solver for WCAG **and** APCA. Public API: `findToneForContrast` (incl. the `preferInitial` tie-break the manual level uses to keep a color's side stable), `findValueForMixContrast`, `resolveContrastForMode`, `resolveContrastForLevel` (both ends resolved, target interpolated for a manual `contrastLevel`; throws on a metric switch), `contrastMetricOf`, `resolveMinContrast`, `apcaContrast`. Closed-form WCAG seed + tone search. |
+| [src/contrast-solver.ts](src/contrast-solver.ts) | Tone-based binary-search solver for WCAG **and** APCA. Public API: `findToneForContrast` (incl. the `preferInitial` tie-break the manual level uses on its normal passes to keep a color's side stable), `findValueForMixContrast`, `resolveContrastForMode`, `resolveContrastForLevel` (both ends resolved, target interpolated for a manual `contrastLevel`; throws on a metric switch), `contrastMetricOf`, `resolveMinContrast`, `apcaContrast`. Closed-form WCAG seed + tone search. |
 | [src/shadow.ts](src/shadow.ts) | Shadow + mix def predicates (`isShadowDef`, `isMixDef`), default `ShadowTuning`, tuning merge, the actual `computeShadow` math (hue blend, saturation cap, lightness clamp, `tanh` alpha curve) operating on OKHSL lightness at the edge, and `circularLerp` for hue. |
-| [src/hc-pair.ts](src/hc-pair.ts) | Tiny shared helpers: HC-pair selection (`pairNormal` / `pairHC`), HC-pair interpolation for the manual contrast level (`contrastFraction`, `levelFraction`, `numberAt`, `parseToneValueAt`, `PAIR_SWITCH`), tone-value parsing (`parseToneValue` for absolute / relative / `'max'`/`'min'` extremes, `isExtremeTone`), root-tone discrimination (`isAbsoluteTone`, now incl. extremes), `clamp` / `lerp`, hue resolution (`resolveEffectiveHue`), relative-value parsing. Leaf module — types only, so every other module can import it. |
+| [src/hc-pair.ts](src/hc-pair.ts) | Tiny shared helpers: HC-pair selection (`pairNormal` / `pairHC`), HC-pair interpolation for the manual contrast level (`contrastFraction`, `hcMirrorsNormal` — the level-100 "HC slots are duplicates" predicate, `levelFraction`, `numberAt`, `parseToneValueAt`, `PAIR_SWITCH`), tone-value parsing (`parseToneValue` for absolute / relative / `'max'`/`'min'` extremes, `isExtremeTone`), root-tone discrimination (`isAbsoluteTone`, now incl. extremes), `clamp` / `lerp`, hue resolution (`resolveEffectiveHue`), relative-value parsing. Leaf module — types only, so every other module can import it. |
 | [src/formatters.ts](src/formatters.ts) | Variant→string dispatch (`okhsl` / `rgb` / `hsl` / `oklch`) and the four token-map shapes Glaze emits: `buildTokenMap` ([Tasty](https://tasty.style) `#name` keys + state aliases), `buildFlatTokenMap` (per-variant maps), `buildJsonMap` (per-color JSON), `buildCssMap` (CSS custom-property declarations). For `splitHue` it emits the light hue declarations plus, via `darkHueDeclarations` in `channels.ts`, the whole dark set when a `darkHue` makes it differ. Also the `resolveModes` helper used everywhere. |
 | [src/okhsl-color-math.ts](src/okhsl-color-math.ts) | OKHSL ↔ linear-sRGB ↔ gamma-sRGB ↔ OKLab conversions, hex parsing (3/6/8 digits), gamut clamping, and the `formatOkhsl` / `formatRgb` / `formatHsl` / `formatOklch` writers. The only file with the actual color science. |
 | [src/config.ts](src/config.ts) | Global config singleton. `defaultConfig()` is the one source of truth for defaults; `configure()` mutates the live object and bumps a monotonic `configVersion` so theme caches invalidate. `snapshotConfig()` powers `glaze.getConfig()`. `freezeConfigForExport()` freezes resolve-relevant fields for authoring export (`pastel` is instance-only; `contrastLevel` is frozen only when instance-authored, since a global level is a live preference). `normalizeContrastLevel()` validates the manual contrast level. |

README.md

@@ -32,7 +32,7 @@ contrast floor.
 - **Mix colors** — blend two colors with OKHSL or sRGB interpolation, opaque or transparent, with optional contrast solving
 - **Shadow colors** — OKHSL-native shadow computation with automatic alpha, fg/bg tinting, and per-scheme adaptation
 - **Light + Dark + High-Contrast** — all schemes from one definition
-- **Manual contrast level** — swap the high-contrast tier for a `0–100` slider; `0` is your normal palette, `100` the high-contrast one, and every level in between is solved, not approximated
+- **Manual contrast level** — put your normal palette on a `0–100` slider between itself and the high-contrast one; every level in between is solved, not approximated, and the high-contrast tier stays available on top
 - **Per-color hue override** — absolute or relative hue shifts within a theme
 - **Multi-format output** — native `rgb`, `hsl`, and `oklch`, plus
   [Tasty](https://tasty.style)-compatible `okhsl` and `okhst`