max / makeover

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1	//! Shared theme loading + intent resolution for TOML-based theme files.
2	//!
3	//! Used by GoingsOn, Balanced Breakfast (Tauri apps), audiofiles (egui), and the
4	//! MNW web server. Themes are authored by intent ("human design"): colors are
5	//! declared by role (surface / content / action / status / line / category), not
6	//! by hue. This crate is the single place that resolves an authored theme into a
7	//! full set of intent tokens — including the derived interactive states
8	//! (hover/active/selection/row-stripe/contrast) that each app used to recompute
9	//! itself — and emits them as CSS variables or RGB tuples.
10	//!
11	//! Theme file shape:
12	//! ```text
13	//! [meta]
14	//! name = "Nord"
15	//! variant = "dark" # or "light"
16	//!
17	//! [surface] # container backgrounds by role/elevation
18	//! page = "#2e3440"; raised = "#3b4252"; sunken = "#434c5e"; overlay = "#3b4252"
19	//!
20	//! [content] # the ink. Its emphasis steps are derived, not authored:
21	//! primary = "#d8dee9" # `content-secondary` and `content-muted` are tonal
22	//! # steps of this toward `surface.page`. See `Emphasis`.
23	//!
24	//! [action] # interactive / brand color
25	//! primary = "#81a1c1"
26	//!
27	//! [status] # state semantics
28	//! danger = "#bf616a"; success = "#a3be8c"; warning = "#ebcb8b"; info = "#88c0d0"
29	//!
30	//! [line]
31	//! border = "#4c566a"
32	//!
33	//! [category] # distinct decorative colors for tags/badges/charts
34	//! one = "#bf616a"; two = "#a3be8c"; three = "#81a1c1"
35	//! four = "#ebcb8b"; five = "#b48ead"; six = "#88c0d0"
36	//! ```
37
38	// Color-space math: single-letter channel names (r/g/b/l/m/s) and the published
39	// high-precision OKLab/sRGB matrix constants are the domain vocabulary here.
40	#![allow(clippy::many_single_char_names, clippy::unreadable_literal)]
41
42	use serde::Serialize;
43	use std::collections::{BTreeMap, HashMap};
44	use std::path::{Path, PathBuf};
45
46	/// The color sections an authored theme may declare.
47	pub const COLOR_SECTIONS: &[&str] = &["surface", "content", "action", "status", "line", "category"];
48
49	/// Theme metadata parsed from the `[meta]` section.
50	#[derive(Debug, Clone, Serialize)]
51	#[serde(rename_all = "camelCase")]
52	pub struct ThemeMeta {
53	pub id: String,
54	pub name: String,
55	pub variant: String,
56	pub is_custom: bool,
57	}
58
59	/// A loaded theme: metadata plus the authored colors, flattened to dotted keys
60	/// (e.g. `"surface.page"`, `"status.danger"`, `"category.one"`).
61	#[derive(Debug, Serialize)]
62	#[serde(rename_all = "camelCase")]
63	pub struct ThemeColors {
64	pub meta: ThemeMeta,
65	pub colors: HashMap<String, String>,
66	}
67
68	// ============================================================================
69	// Color math — perceptual (OKLab) derivations + WCAG contrast.
70	//
71	// Interactive states (hover/active/selection/surfaces) are derived in OKLab so
72	// equal steps look equal across every theme's hues (Ottosson 2020; the modern
73	// CIELAB). Text-on-color is picked by the WCAG 2.x contrast ratio, not a naive
74	// luminance threshold, so the choice actually meets AA where achievable.
75	// This is the single source of truth shared by every product.
76	// ============================================================================
77
78	/// An sRGB color. Hex round-trips losslessly.
79	#[derive(Clone, Copy, Debug, PartialEq, Eq)]
80	pub struct Rgb {
81	pub r: u8,
82	pub g: u8,
83	pub b: u8,
84	}
85
86	impl Rgb {
87	/// Parse `#rgb` or `#rrggbb` (case-insensitive). Returns `None` otherwise.
88	pub fn from_hex(s: &str) -> Option<Rgb> {
89	let h = s.strip_prefix('#')?;
90	let (r, g, b) = match h.len() {
91	6 => (
92	u8::from_str_radix(&h[0..2], 16).ok()?,
93	u8::from_str_radix(&h[2..4], 16).ok()?,
94	u8::from_str_radix(&h[4..6], 16).ok()?,
95	),
96	3 => {
97	let d = \|c: &str\| u8::from_str_radix(c, 16).ok().map(\|v\| v * 17);
98	(d(&h[0..1])?, d(&h[1..2])?, d(&h[2..3])?)
99	}
100	_ => return None,
101	};
102	Some(Rgb { r, g, b })
103	}
104
105	/// Lowercase `#rrggbb`.
106	pub fn to_hex(self) -> String {
107	format!("#{:02x}{:02x}{:02x}", self.r, self.g, self.b)
108	}
109
110	pub fn tuple(self) -> (u8, u8, u8) {
111	(self.r, self.g, self.b)
112	}
113	}
114
115	/// A color in OKLab (perceptually uniform): `l` lightness in [0,1], `a`/`b` opponent axes.
116	#[derive(Clone, Copy, Debug)]
117	pub struct Oklab {
118	pub l: f32,
119	pub a: f32,
120	pub b: f32,
121	}
122
123	fn srgb_to_linear(c: u8) -> f32 {
124	let c = c as f32 / 255.0;
125	if c <= 0.04045 {
126	c / 12.92
127	} else {
128	((c + 0.055) / 1.055).powf(2.4)
129	}
130	}
131
132	fn linear_to_srgb(c: f32) -> u8 {
133	let c = c.clamp(0.0, 1.0);
134	let v = if c <= 0.0031308 {
135	c * 12.92
136	} else {
137	1.055 * c.powf(1.0 / 2.4) - 0.055
138	};
139	(v * 255.0).round().clamp(0.0, 255.0) as u8
140	}
141
142	impl Rgb {
143	/// Convert to OKLab (Ottosson's sRGB matrices).
144	///
145	/// The matrix coefficients are quoted at their published precision so they
146	/// can be diffed against the reference. `f32` rounds them at compile time;
147	/// truncating the literals would only make them harder to check.
148	#[allow(clippy::excessive_precision)]
149	pub fn to_oklab(self) -> Oklab {
150	let (r, g, b) = (
151	srgb_to_linear(self.r),
152	srgb_to_linear(self.g),
153	srgb_to_linear(self.b),
154	);
155	let l = 0.4122214708 * r + 0.5363325363 * g + 0.0514459929 * b;
156	let m = 0.2119034982 * r + 0.6806995451 * g + 0.1073969566 * b;
157	let s = 0.0883024619 * r + 0.2817188376 * g + 0.6299787005 * b;
158	let (l_, m_, s_) = (l.cbrt(), m.cbrt(), s.cbrt());
159	Oklab {
160	l: 0.2104542553 * l_ + 0.7936177850 * m_ - 0.0040720468 * s_,
161	a: 1.9779984951 * l_ - 2.4285922050 * m_ + 0.4505937099 * s_,
162	b: 0.0259040371 * l_ + 0.7827717662 * m_ - 0.8086757660 * s_,
163	}
164	}
165
166	/// Convert from OKLab back to the nearest in-gamut sRGB.
167	///
168	/// Published precision, as in [`Rgb::to_oklab`].
169	#[allow(clippy::excessive_precision)]
170	pub fn from_oklab(c: Oklab) -> Rgb {
171	let l_ = c.l + 0.3963377774 * c.a + 0.2158037573 * c.b;
172	let m_ = c.l - 0.1055613458 * c.a - 0.0638541728 * c.b;
173	let s_ = c.l - 0.0894841775 * c.a - 1.2914855480 * c.b;
174	let (l, m, s) = (l_ * l_ * l_, m_ * m_ * m_, s_ * s_ * s_);
175	Rgb {
176	r: linear_to_srgb(4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s),
177	g: linear_to_srgb(-1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s),
178	b: linear_to_srgb(-0.0041960863 * l - 0.7034186147 * m + 1.7076147010 * s),
179	}
180	}
181	}
182
183	/// WCAG 2.x relative luminance of an sRGB color.
184	fn rel_luminance(c: Rgb) -> f32 {
185	0.2126 * srgb_to_linear(c.r) + 0.7152 * srgb_to_linear(c.g) + 0.0722 * srgb_to_linear(c.b)
186	}
187
188	/// WCAG 2.x contrast ratio between two colors, in [1, 21].
189	pub fn wcag_contrast(a: Rgb, b: Rgb) -> f32 {
190	let (la, lb) = (rel_luminance(a), rel_luminance(b));
191	let (hi, lo) = if la >= lb { (la, lb) } else { (lb, la) };
192	(hi + 0.05) / (lo + 0.05)
193	}
194
195	/// Pick black or white for legible text on `bg`, by the higher WCAG contrast
196	/// ratio (so the choice meets AA wherever the background allows it).
197	pub fn readable_on(bg: Rgb) -> Rgb {
198	let white = Rgb {
199	r: 255,
200	g: 255,
201	b: 255,
202	};
203	let black = Rgb { r: 0, g: 0, b: 0 };
204	if wcag_contrast(white, bg) >= wcag_contrast(black, bg) {
205	white
206	} else {
207	black
208	}
209	}
210
211	/// Shift OKLab lightness by `delta` (perceptually uniform). Positive lightens.
212	pub fn lighten(c: Rgb, delta: f32) -> Rgb {
213	let mut lab = c.to_oklab();
214	lab.l = (lab.l + delta).clamp(0.0, 1.0);
215	Rgb::from_oklab(lab)
216	}
217
218	/// Shift OKLab lightness down by `delta` (perceptually uniform).
219	pub fn darken(c: Rgb, delta: f32) -> Rgb {
220	lighten(c, -delta)
221	}
222
223	/// Interpolate between `a` and `b` by `t` in [0,1] in OKLab (perceptual blend).
224	pub fn mix(a: Rgb, b: Rgb, t: f32) -> Rgb {
225	let (x, y) = (a.to_oklab(), b.to_oklab());
226	Rgb::from_oklab(Oklab {
227	l: x.l + (y.l - x.l) * t,
228	a: x.a + (y.a - x.a) * t,
229	b: x.b + (y.b - x.b) * t,
230	})
231	}
232
233	// ============================================================================
234	// Tonal steps
235	// ============================================================================
236
237	/// How far a tonal step sits from the token it is a step of.
238	///
239	/// The named ratios. [`tonal`] is the same operation with the number written
240	/// out, and this is the small set of steps the vocabulary has agreed on, so a
241	/// consumer asking for "the muted form of this" names it rather than picking a
242	/// number and disagreeing with the next consumer to pick one.
243	///
244	/// The rule these encode, stated as the three-tone convention:
245	///
246	/// \| step \| what it means \|
247	/// \|------\|---------------\|
248	/// \| [`Full`](Self::Full) \| active, emphasised, the thing itself \|
249	/// \| [`Secondary`](Self::Secondary) \| inactive but usable: a control that still answers \|
250	/// \| [`Muted`](Self::Muted) \| inert: disabled, or not a control at all \|
251	#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
252	pub enum Emphasis {
253	/// The token unchanged.
254	Full,
255	/// One step back. Still legible as content, not competing with `Full`.
256	Secondary,
257	/// Two steps back. Present, and saying it is not the point.
258	Muted,
259	}
260
261	impl Emphasis {
262	/// The fraction of the way to the ground this step travels.
263	///
264	/// Both numbers are the shipped corpus' own, not invented: across the 31
265	/// bundled themes, hand-authored `content.secondary` sat at a median 0.115
266	/// of the way from `content.primary` to `surface.page`, and `content.muted`
267	/// at 0.424. So the derivation reproduces what theme authors converged on
268	/// by eye, and the themes that move are the ones that were off the cluster.
269	#[must_use]
270	pub const fn ratio(self) -> f32 {
271	match self {
272	Self::Full => 0.0,
273	Self::Secondary => 0.12,
274	Self::Muted => 0.42,
275	}
276	}
277
278	/// The suffix a derived token takes, or `None` for the token itself.
279	///
280	/// `content` + [`Muted`](Self::Muted) is `content-muted`, which is the
281	/// naming every consumer already spells by hand. Grouping a family this way
282	/// is what makes `danger-muted` or `action-secondary` nameable without a
283	/// second table saying what they mean.
284	#[must_use]
285	pub const fn suffix(self) -> Option<&'static str> {
286	match self {
287	Self::Full => None,
288	Self::Secondary => Some("-secondary"),
289	Self::Muted => Some("-muted"),
290	}
291	}
292
293	/// The derived token key for `token` at this step.
294	#[must_use]
295	pub fn token(self, token: &str) -> String {
296	match self.suffix() {
297	Some(suffix) => format!("{token}{suffix}"),
298	None => token.to_string(),
299	}
300	}
301	}
302
303	/// The contrast a tonal step must clear against the token it is a step of.
304	///
305	/// A ratio says how far to travel, not how far that lands, and the two are the
306	/// same thing only when the base has room to travel in. Across the bundled
307	/// themes a derived `content.secondary` sits between 1.21 and 1.44 of its ink;
308	/// the exceptions were the two themes whose ink is `#000000`, where OKLab L is
309	/// 0, 12 percent of nothing is nothing, and the sRGB transfer curve compresses
310	/// what is left into a 3/255 move. So the floor is the bottom of the band the
311	/// healthy themes already reach, and a theme inside it does not move.
312	///
313	/// Deliberately below [`DISTINCT`]: that is the 3:1 two areas need to read as
314	/// separate, and an emphasis step is one voice quieter rather than a second
315	/// region. Asking 3:1 of it would flatten every theme's ramp into three widely
316	/// spaced greys.
317	pub const STEP_FLOOR: f32 = 1.21;
318
319	/// A tonal step of `base`, `ratio` of the way toward the `ground` it is read
320	/// against.
321	///
322	/// The numerical form of [`Emphasis`], for a consumer that wants a step the
323	/// named set does not have. `ratio` is clamped to [0,1]: past 1 the step is no
324	/// longer a step of `base` but a colour beyond the ground, which is a different
325	/// operation wearing this one's name.
326	///
327	/// # Toward the ground, not toward grey
328	///
329	/// A tonal step is a reduction in contrast against what it is read on, so it
330	/// interpolates toward the surface rather than desaturating or lightening. That
331	/// is why it takes two colours: lightening is wrong on a light theme and
332	/// darkening is wrong on a dark one, and mixing toward the ground is correct on
333	/// both without asking which theme this is. It is also why the ground is a
334	/// parameter rather than assumed — text in a well is read against the well.
335	///
336	/// # It composes
337	///
338	/// Two steps toward the same ground are one step toward that ground, since
339	/// OKLab interpolation is linear: `tonal(tonal(c, g, a), g, b)` is
340	/// `tonal(c, g, a + b - a*b)`. So a family can be derived recursively — the
341	/// muted form of a secondary is a well-defined colour and not a compounding
342	/// error — and re-deriving a token that was already derived is stable rather
343	/// than a slow slide into the background.
344	#[must_use]
345	pub fn tonal(base: Rgb, ground: Rgb, ratio: f32) -> Rgb {
346	mix(base, ground, ratio.clamp(0.0, 1.0))
347	}
348
349	/// A named tonal step of `base` against the `ground` it is read on.
350	///
351	/// [`tonal`] with [`Emphasis::ratio`], and the form to reach for: the two
352	/// spellings of "muted" a pair of consumers pick independently are the drift
353	/// this replaces.
354	#[must_use]
355	pub fn emphasized(base: Rgb, ground: Rgb, emphasis: Emphasis) -> Rgb {
356	tonal(base, ground, emphasis.ratio())
357	}
358
359	// ============================================================================
360	// Low-color terminals
361	// ============================================================================
362
363	/// The 16 colors an ANSI terminal addresses by index, in the PC/VGA
364	/// arrangement the Linux console and most emulators start from.
365	///
366	/// 0-7 are the normal colors and 8-15 the bright ones. Index 7 is a light gray
367	/// rather than white, which is the entry a themed surface usually lands on, and
368	/// index 15 is the true white.
369	///
370	/// Emulators let the user repaint all sixteen, so this is the standard
371	/// arrangement rather than a promise about any one terminal. The Linux console
372	/// keeps it, which is the case that matters: a console app cannot fall back to
373	/// 24-bit color there.
374	pub const ANSI_16: [Rgb; 16] = [
375	Rgb {
376	r: 0x00,
377	g: 0x00,
378	b: 0x00,
379	},
380	Rgb {
381	r: 0xaa,
382	g: 0x00,
383	b: 0x00,
384	},
385	Rgb {
386	r: 0x00,
387	g: 0xaa,
388	b: 0x00,
389	},
390	Rgb {
391	r: 0xaa,
392	g: 0x55,
393	b: 0x00,
394	},
395	Rgb {
396	r: 0x00,
397	g: 0x00,
398	b: 0xaa,
399	},
400	Rgb {
401	r: 0xaa,
402	g: 0x00,
403	b: 0xaa,
404	},
405	Rgb {
406	r: 0x00,
407	g: 0xaa,
408	b: 0xaa,
409	},
410	Rgb {
411	r: 0xaa,
412	g: 0xaa,
413	b: 0xaa,
414	},
415	Rgb {
416	r: 0x55,
417	g: 0x55,
418	b: 0x55,
419	},
420	Rgb {
421	r: 0xff,
422	g: 0x55,
423	b: 0x55,
424	},
425	Rgb {
426	r: 0x55,
427	g: 0xff,
428	b: 0x55,
429	},
430	Rgb {
431	r: 0xff,
432	g: 0xff,
433	b: 0x55,
434	},
435	Rgb {
436	r: 0x55,
437	g: 0x55,
438	b: 0xff,
439	},
440	Rgb {
441	r: 0xff,
442	g: 0x55,
443	b: 0xff,
444	},
445	Rgb {
446	r: 0x55,
447	g: 0xff,
448	b: 0xff,
449	},
450	Rgb {
451	r: 0xff,
452	g: 0xff,
453	b: 0xff,
454	},
455	];
456
457	/// The 256 colors an xterm-compatible terminal addresses by index, so that
458	/// entry `i` is what the terminal paints for `38;5;i`.
459	///
460	/// Three regions, and they are not equally trustworthy. 0-15 are the [`ANSI_16`]
461	/// system colors, which every emulator lets the user repaint. 16-231 are a
462	/// 6x6x6 RGB cube and 232-255 a 24-step gray ramp, and those 240 are fixed.
463	///
464	/// So a color whose whole job is to be told apart from another should quantize
465	/// against [`ANSI_240`] rather than against this table: a match landing in the
466	/// low sixteen is a match against a color the user may have moved.
467	pub const ANSI_256: [Rgb; 256] = build_ansi_256();
468
469	/// The fixed region of [`ANSI_256`]: the 6x6x6 cube and the gray ramp, without
470	/// the sixteen repaintable system colors.
471	///
472	/// Quantizing against this returns an index into this slice; add
473	/// [`ANSI_240_OFFSET`] to get the index the terminal wants.
474	pub const ANSI_240: &[Rgb] = ANSI_256.split_at(16).1;
475
476	/// What to add to an [`ANSI_240`] index to get an [`ANSI_256`] one.
477	pub const ANSI_240_OFFSET: usize = 16;
478
479	/// The twelve chromatic ANSI slots, as the intents that paint them.
480	///
481	/// Indexed 1-6 and 9-14. The hues do not depend on whether the theme is light
482	/// or dark, since red is the theme's danger tone either way, which is exactly
483	/// why the four achromatic slots are not in this table.
484	///
485	/// Lifted from Alloy's `skelgen` on 2026-07-31, which had folded three
486	/// disagreeing hand-maintained copies into one and is the reason the
487	/// arrangement is trusted. It moved here so a program that paints its own
488	/// palette at runtime, rather than reading a generated config, resolves the
489	/// same slots. Slot 14 was the one the copies disagreed on and is
490	/// `category.six`, which both the Linux console table and the retired
491	/// `vtrgb.py` had.
492	const CHROMATIC: [(usize, &str); 12] = [
493	(1, "status.danger"),
494	(2, "status.success"),
495	(3, "status.warning"),
496	(4, "status.info"),
497	(5, "category.five"),
498	(6, "category.six"),
499	(9, "action.primary"), // bright red, the theme's warm accent
500	(10, "status.success"),
501	(11, "status.warning"),
502	(12, "status.info"),
503	(13, "category.five"),
504	(14, "category.six"),
505	];
506
507	/// The four achromatic slots, 0, 7, 8 and 15, which invert with the theme.
508	///
509	/// These are the slots a naive table gets wrong. ANSI 0 is "black" and 7 is
510	/// "white", but what a terminal wants there is the darkest tone and *the
511	/// lightest tone*, and which intent that is flips with the theme's polarity. A
512	/// light theme's darkest tone is its ink; a dark theme's is its deepest
513	/// surface. Pinning slot 0 to `content.primary` reads correctly on a light
514	/// theme and hands a dark one a pale cream as "black".
515	///
516	/// Slot 7 is a surface and not a text tone, because it is what a program with
517	/// no way to name anything else draws its container on: a greeter's login card
518	/// is a light card on the darker field slot 0 paints.
519	///
520	/// Anything that is not `dark`, including `high-contrast`, follows the light
521	/// anchors.
522	fn achromatic_slot(index: usize, variant: &str) -> Option<&'static str> {
523	let dark = variant == "dark";
524	Some(match (index, dark) {
525	(0, false) => "content.primary", // darkest text tone
526	(0, true) => "surface.sunken", // darkest surface
527	(7, false) => "surface.raised", // the login card
528	(7, true) => "content.secondary", // a readable light tone
529	(8, _) => "content.muted", // muted chrome, either way
530	(15, false) => "surface.overlay", // lightest surface
531	(15, true) => "content.primary", // lightest text tone
532	_ => return None,
533	})
534	}
535
536	/// The authored intent painting ANSI slot `index` under a theme of `variant`,
537	/// as a dotted key into [`ThemeColors::colors`].
538	///
539	/// `None` for an index outside 0-15. Every slot in range resolves, so a caller
540	/// that has the intent can fill all sixteen.
541	///
542	/// This is what makes a bare console, a terminal emulator and a generated
543	/// config agree on what red means. They disagreed for as long as each kept its
544	/// own table.
545	#[must_use]
546	pub fn ansi_intent(index: usize, variant: &str) -> Option<&'static str> {
547	achromatic_slot(index, variant).or_else(\|\| {
548	CHROMATIC
549	.iter()
550	.find(\|(slot, _)\| *slot == index)
551	.map(\|(_, intent)\| *intent)
552	})
553	}
554
555	const fn build_ansi_256() -> [Rgb; 256] {
556	let mut table = [Rgb { r: 0, g: 0, b: 0 }; 256];
557
558	let mut i = 0;
559	while i < 16 {
560	table[i] = ANSI_16[i];
561	i += 1;
562	}
563
564	// The cube's six levels are not evenly spaced. The step from black to the
565	// first is more than twice any later one, which is xterm's arrangement
566	// rather than a choice available here, and it is why the darkest tones a
567	// theme can reach on 256 colors come from the gray ramp instead.
568	const LEVELS: [u8; 6] = [0, 95, 135, 175, 215, 255];
569	let mut r = 0;
570	while r < 6 {
571	let mut g = 0;
572	while g < 6 {
573	let mut b = 0;
574	while b < 6 {
575	table[16 + 36 * r + 6 * g + b] = Rgb {
576	r: LEVELS[r],
577	g: LEVELS[g],
578	b: LEVELS[b],
579	};
580	b += 1;
581	}
582	g += 1;
583	}
584	r += 1;
585	}
586
587	// 8 to 238 in steps of 10. Neither end is black or white; both of those are
588	// in the cube, so the ramp is 24 steps of gray between them rather than 24
589	// steps of the whole range.
590	let mut k = 0;
591	while k < 24 {
592	let v = 8 + 10 * k as u8;
593	table[232 + k as usize] = Rgb { r: v, g: v, b: v };
594	k += 1;
595	}
596
597	table
598	}
599
600	/// The contrast ratio two colors must clear to read as separate areas.
601	///
602	/// WCAG 2.x asks 3:1 of user interface components and graphics, which is what
603	/// a border, a rule, or a focus ring is. Text wants more, and a caller drawing
604	/// text can ask for more by checking [`wcag_contrast`] itself.
605	pub const DISTINCT: f32 = 3.0;
606
607	/// Perceptual distance between two colors, for choosing the closest of a set.
608	fn oklab_distance(a: Rgb, b: Rgb) -> f32 {
609	let (x, y) = (a.to_oklab(), b.to_oklab());
610	((x.l - y.l).powi(2) + (x.a - y.a).powi(2) + (x.b - y.b).powi(2)).sqrt()
611	}
612
613	/// Index of the entry in `palette` that looks most like `c`.
614	///
615	/// OKLab distance rather than distance in sRGB, for the same reason [`mix`]
616	/// interpolates there: sRGB's numbers are not spaced the way seeing is, so a
617	/// nearest match computed in it picks visibly wrong entries in the mid tones.
618	///
619	/// # Panics
620	///
621	/// If `palette` is empty.
622	pub fn quantize(c: Rgb, palette: &[Rgb]) -> usize {
623	assert!(!palette.is_empty(), "a palette needs at least one color");
624	let mut best = 0;
625	let mut best_distance = f32::INFINITY;
626	for (index, entry) in palette.iter().enumerate() {
627	let distance = oklab_distance(c, *entry);
628	if distance < best_distance {
629	best = index;
630	best_distance = distance;
631	}
632	}
633	best
634	}
635
636	/// Index of the entry in `palette` closest to `fg` that still reads against
637	/// `bg`.
638	///
639	/// [`quantize`] answers about one color at a time, and two colors that differ
640	/// can quantize to the same entry: a themed page and a border drawn on it are
641	/// often a few steps apart in a 24-bit theme and land together on a 16-color
642	/// terminal, leaving one flat area where there was a frame. Alloy's console
643	/// showed exactly this, and it is not a contrived pairing: a light page and the
644	/// mid-tone border derived from it both land on index 7.
645	///
646	/// So the background is quantized first, because what the border must be
647	/// distinguished from is the entry the terminal will actually paint, not the
648	/// color the theme asked for. Then the nearest entry to `fg` clearing
649	/// [`DISTINCT`] against it wins. When nothing clears it, the entry that gets
650	/// furthest does: at that point the palette cannot honor the design, and the
651	/// most legible approximation beats the closest invisible one.
652	///
653	/// Only for colors whose whole job is to be told apart from their background.
654	/// Applied to every token it would push a deliberately quiet one until it
655	/// shouted.
656	///
657	/// # Panics
658	///
659	/// If `palette` is empty.
660	pub fn quantize_against(fg: Rgb, bg: Rgb, palette: &[Rgb]) -> usize {
661	assert!(!palette.is_empty(), "a palette needs at least one color");
662	let shown = palette[quantize(bg, palette)];
663
664	let mut order: Vec<usize> = (0..palette.len()).collect();
665	order.sort_by(\|a, b\| {
666	oklab_distance(fg, palette[a]).total_cmp(&oklab_distance(fg, palette[b]))
667	});
668
669	order
670	.iter()
671	.copied()
672	.find(\|index\| wcag_contrast(palette[*index], shown) >= DISTINCT)
673	.unwrap_or_else(\|\| {
674	order
675	.iter()
676	.copied()
677	.max_by(\|a, b\| {
678	wcag_contrast(palette[a], shown).total_cmp(&wcag_contrast(palette[b], shown))
679	})
680	.expect("the palette is not empty")
681	})
682	}
683
684	// ============================================================================
685	// Intent resolution
686	// ============================================================================
687
688	/// Base intents: (TOML dotted source key, canonical token key). The token key
689	/// is the CSS-var stem (`--{token}`) and the `rgb()` lookup key.
690	///
691	/// Read straight from the loaded theme, which is not quite the same as read
692	/// from the file: `content.secondary` and `content.muted` are tonal steps of
693	/// `content.primary` and are filled in at load by [`derive_tonal_steps`], so
694	/// they arrive here already computed and take this path like any other.
695	pub const BASE_INTENTS: &[(&str, &str)] = &[
696	("surface.page", "surface-page"),
697	("surface.raised", "surface-raised"),
698	("surface.sunken", "surface-sunken"),
699	("surface.overlay", "surface-overlay"),
700	("content.primary", "content"),
701	("content.secondary", "content-secondary"),
702	("content.muted", "content-muted"),
703	("action.primary", "action"),
704	("status.danger", "danger"),
705	("status.success", "success"),
706	("status.warning", "warning"),
707	("status.info", "info"),
708	("line.border", "border"),
709	("category.one", "category-one"),
710	("category.two", "category-two"),
711	("category.three", "category-three"),
712	("category.four", "category-four"),
713	("category.five", "category-five"),
714	("category.six", "category-six"),
715	];
716
717	/// A fully resolved intent layer: every token key → concrete `#rrggbb`.
718	/// Includes both authored base intents and the computed derived intents.
719	#[derive(Debug, Clone, Serialize)]
720	#[serde(rename_all = "camelCase")]
721	pub struct SemanticTokens {
722	pub meta: ThemeMeta,
723	/// token-key → resolved hex. Stable, deterministic ordering.
724	pub intents: BTreeMap<String, String>,
725	}
726
727	impl SemanticTokens {
728	/// Resolved hex for a token key, if present.
729	pub fn hex(&self, key: &str) -> Option<&str> {
730	self.intents.get(key).map(String::as_str)
731	}
732
733	/// Resolved RGB tuple for a token key (for egui / native consumers).
734	///
735	/// `None` for a translucent token. Two intents are emitted as `rgba(...)`
736	/// rather than hex, `overlay` and `elevation`, and dropping the alpha would
737	/// hand a native consumer an opaque near-black where it asked for a scrim.
738	/// Those want [`rgba`](Self::rgba).
739	pub fn rgb(&self, key: &str) -> Option<(u8, u8, u8)> {
740	self.intents
741	.get(key)
742	.and_then(\|h\| Rgb::from_hex(h))
743	.map(Rgb::tuple)
744	}
745
746	/// Resolved RGBA tuple for a token key, alpha as 0-255.
747	///
748	/// Reads both spellings, so a caller that does not care whether an intent
749	/// happens to be translucent can use this for everything: an opaque token
750	/// comes back at 255.
751	///
752	/// It exists because a CSS consumer can take `rgba(...)` as a string
753	/// straight out of [`hex`](Self::hex) and a native one cannot. Without it
754	/// the two translucent intents are reachable from a stylesheet and from
755	/// nowhere else, which is the coupling deriving in the crate was meant to
756	/// avoid.
757	pub fn rgba(&self, key: &str) -> Option<(u8, u8, u8, u8)> {
758	let value = self.intents.get(key)?;
759	if let Some(rgb) = Rgb::from_hex(value) {
760	let (r, g, b) = rgb.tuple();
761	return Some((r, g, b, 255));
762	}
763	let inner = value.strip_prefix("rgba(")?.strip_suffix(')')?;
764	let mut parts = inner.split(',').map(str::trim);
765	let r = parts.next()?.parse().ok()?;
766	let g = parts.next()?.parse().ok()?;
767	let b = parts.next()?.parse().ok()?;
768	let alpha: f32 = parts.next()?.parse().ok()?;
769	if parts.next().is_some() \|\| !(0.0..=1.0).contains(&alpha) {
770	return None;
771	}
772	Some((r, g, b, (alpha * 255.0).round() as u8))
773	}
774	}
775
776	/// Resolve an authored theme into the full intent token set.
777	///
778	/// 1. Copy each present base intent from the authored colors.
779	/// 2. Compute the derived interactive states from the base intents, using the
780	/// same math the apps used to apply individually (so output is identical).
781	///
782	/// Each derived token is emitted only when its source intents exist, mirroring
783	/// the skip-missing behavior of the rest of the crate.
784	pub fn resolve(theme: &ThemeColors) -> SemanticTokens {
785	let mut intents: BTreeMap<String, String> = BTreeMap::new();
786
787	// 1. Base intents (authored). Copy only values that parse as a hex color and
788	// re-emit them in canonical `#rrggbb` form, so an authored value can never
789	// carry arbitrary bytes into the emitted CSS (the resolved tokens are inlined
790	// raw into a `<style>` block by the web server). A malformed value is skipped,
791	// mirroring the skip-missing behavior for absent intents.
792	for (src, token) in BASE_INTENTS {
793	if let Some(rgb) = theme.colors.get(*src).and_then(\|v\| Rgb::from_hex(v)) {
794	intents.insert((*token).to_string(), rgb.to_hex());
795	}
796	}
797
798	// Helper: parse an already-resolved token to Rgb.
799	let get = \|m: &BTreeMap<String, String>, k: &str\| m.get(k).and_then(\|h\| Rgb::from_hex(h));
800
801	// 2. Derived intents — perceptual (OKLab) steps + WCAG-picked text.
802	// Lightness deltas are in OKLab L units; mix ratios interpolate in OKLab.
803	let mut derived: Vec<(String, Rgb)> = Vec::new();
804	if let Some(action) = get(&intents, "action") {
805	derived.push(("action-hover".into(), lighten(action, 0.05)));
806	derived.push(("content-on-action".into(), readable_on(action)));
807	// The focus ring is the action colour itself, not a tint of it: a ring
808	// is a statement that the keyboard is here, and a faded one reads as a
809	// disabled control rather than an emphatic one.
810	//
811	// One ring, not one per primitive. Where the ring sits is a depth
812	// question and not a per-component choice: a well takes it inside its
813	// own edge and a raised surface takes it outside. That is one decision
814	// with two renderings rather than one decision per component, which is
815	// how the three apps ended up with three rings. This token is the one
816	// shared artifact; which thing wears it, and how it is drawn, is each
817	// renderer's own (see `makeover_layout`'s crate header, "reach, focus
818	// and the focus ring").
819	derived.push(("focus-ring".into(), action));
820	}
821	if let Some(page) = get(&intents, "surface-page") {
822	// Modal scrim: a near-black tone carrying a faint hint of the theme's
823	// hue, at 50% alpha. Anchored very dark (OKLab L=0.08) so it dims the
824	// page on light and dark themes. Emitted as rgba (not a flat hex), so
825	// it is inserted directly rather than through the hex loop below.
826	let mut o = page.to_oklab();
827	o.l = 0.08;
828	let s = Rgb::from_oklab(o);
829	intents.insert(
830	"overlay".into(),
831	format!("rgba({}, {}, {}, 0.5)", s.r, s.g, s.b),
832	);
833
834	// What a surface that FLOATS OVER the page is cast onto it with.
835	//
836	// The one intent here about a surface's relationship to the page rather
837	// than about the surface itself, which is why it is derived from `page`
838	// and not from `surface-raised`. A shadow is not the thing, it is the
839	// absence of light on what is behind the thing.
840	//
841	// SCOPE, and it is the whole point of this intent existing rather than
842	// a general "shadow": a surface that overlays the page takes this, a
843	// surface IN the page takes a bevel. Menus, toasts, popovers and
844	// dropdowns overlay. A card, a plate and a framed image do not, and
845	// reaching for this on one of those is how a pre-Platinum look survives
846	// a conversion wearing a token's name. `.raised` is the answer there.
847	//
848	// Same anchor as the scrim above and for the same reason: a tone read
849	// off the theme's hue but pinned very dark, so it reads as absence of
850	// light on a light theme and on a dark one alike. A shadow tinted to a
851	// dark theme's own lightness would not be a shadow.
852	//
853	// The alpha is the only number here that is a look decision rather than
854	// a derivation. 0.18 sits between the two literal scales it replaces:
855	// the MNW server's --shadow-2 (0.10) reads as nothing under a menu, and
856	// its --shadow-3 (0.15) was measured invisible at plate size. Geometry
857	// stays with the consumer, the way bevel thickness does.
858	intents.insert(
859	"elevation".into(),
860	format!("rgba({}, {}, {}, 0.18)", s.r, s.g, s.b),
861	);
862	}
863	if let Some(raised) = get(&intents, "surface-raised") {
864	// The two edges of a bevel: a raised control is lit from the top left,
865	// so its top and left edges take `bevel-light` and its bottom and right
866	// edges `bevel-dark`. Inverting the pair gives a pressed state and an
867	// inset well, which is what makes the idiom cheap for a consumer.
868	//
869	// Derived here rather than composed per-app because the two webviews
870	// could do it in `color-mix()` and audiofiles, which is egui, could not.
871	// Geometry (thickness, radius, which side gets which) stays app-side.
872	//
873	// The deltas are asymmetric because the eye is: an equal step down reads
874	// as a smaller change than the same step up, so the shadow is cut deeper
875	// than the highlight is raised.
876	//
877	// A face already at the top of the ramp cannot hold a highlight — the
878	// lightening clamps and the control bevels on two sides without ever
879	// resolving as lit. That is a property of the theme, not of this
880	// derivation; `bevel_edges_are_distinct_from_their_face` names the
881	// shipped themes it currently bites.
882	derived.push(("bevel-light".into(), lighten(raised, 0.14)));
883	derived.push(("bevel-dark".into(), darken(raised, 0.18)));
884
885	// An inset well: the content surface inside a raised container, so a
886	// list reads as content in a container rather than as bands on a panel.
887	// `surface-sunken` cannot serve, because a theme is free to author it
888	// darker than raised (goingson does) and a well has to go the other way.
889	//
890	// Which way is "the other way" depends on the theme, and this is the one
891	// derivation here that inverts. A well is lighter than its face on a
892	// light theme and darker on a dark one, where the bevel pair sidesteps
893	// the question by emitting both directions at once.
894	//
895	// Read the direction off `content` rather than off `Variant`. A theme
896	// whose text is dark is a theme whose surfaces are light, whatever its
897	// `variant` field claims, so this resolves correctly even when that
898	// field is wrong and it keeps the branch on measured color rather than
899	// on metadata.
900	//
901	// Deltas are asymmetric for the same reason the bevel's are, and smaller
902	// than the bevel's because a well is an area rather than an edge. The
903	// step up is the specimen's, measured: #D9DDF4 to #F3F5FD is 0.069.
904	//
905	// A face at the top of its ramp cannot hold a lighter well, the same
906	// clamp `bevel-light` hits; `well_is_visible_against_its_face` names the
907	// shipped themes where it bites.
908	if let Some(content) = get(&intents, "content") {
909	let content_is_darker = content.to_oklab().l < raised.to_oklab().l;
910	let well = if content_is_darker {
911	lighten(raised, 0.07)
912	} else {
913	darken(raised, 0.09)
914	};
915	derived.push(("surface-well".into(), well));
916	}
917	}
918	if let Some(sunken) = get(&intents, "surface-sunken") {
919	derived.push(("hover-surface".into(), sunken));
920	}
921	if let Some(border) = get(&intents, "border") {
922	derived.push(("border-strong".into(), darken(border, 0.05)));
923	}
924
925	for (token, rgb) in derived {
926	intents.insert(token, rgb.to_hex());
927	}
928
929	SemanticTokens {
930	meta: theme.meta.clone(),
931	intents,
932	}
933	}
934
935	/// Emit the resolved intent layer as CSS declarations (no selector), one
936	/// ` --token: #hex;` line each, in deterministic (BTreeMap) order.
937	pub fn intent_css_declarations(tokens: &SemanticTokens) -> String {
938	let mut out = String::new();
939	for (token, hex) in &tokens.intents {
940	out.push_str(" --");
941	out.push_str(token);
942	out.push_str(": ");
943	out.push_str(hex);
944	out.push_str(";\n");
945	}
946	out
947	}
948
949	/// Emit the resolved intent layer as a `:root { … }` block — the single TOML →
950	/// CSS mapping every web surface injects.
951	pub fn intent_css_vars(tokens: &SemanticTokens) -> String {
952	format!(":root {{\n{}}}\n", intent_css_declarations(tokens))
953	}
954
955	// ============================================================================
956	// Typography — layer 1 of the house font model.
957	//
958	// Wiki `typography-standard`. The model is three layers: an app override, the
959	// house default, then a system generic, and this is the middle one. Two needs,
960	// two names, and no others in the suite:
961	//
962	// --font-mono Quasi Mono -> monospace
963	// --font-sans Quasi Body -> sans-serif
964	//
965	// Both are cut by `quasi-type` from the Atkinson Hyperlegible superfamily plus
966	// the house glyph set. This crate does not cut them and cannot: quasi-type is
967	// `publish = false` and makeover is on crates.io, so the cut lives in each
968	// consumer's own build script (`quasi_type::cut`, taken as a git dependency,
969	// the way `shop-font` does it). What lives here is the vocabulary, which is
970	// the half that was scattered.
971	//
972	// Font is not a theme's business and none of this is themeable. A theme
973	// declares colour by role; nothing in a theme file names a face, and the two
974	// tokens below are the same in every theme. That is why they are constants
975	// rather than another section of `SemanticTokens`, and why they belong in a
976	// stylesheet generated once at build time rather than in the block that gets
977	// re-injected on a theme switch.
978	//
979	// The brand/display tier is out of scope, per product and by decision: Young
980	// Serif on MNW, Reglo in GoingsOn, Departure Mono on Alloy, audiofiles' logo
981	// face. No renderer emits them and no described screen resolves a token to
982	// one, so they keep their own `font-family` until the app-override layer
983	// lands and gives them a place to be declared.
984	// ============================================================================
985
986	/// The mono slot: code, data, identifiers, cell grids, anything monospaced.
987	pub const FONT_MONO: &str = "\"Quasi Mono\", monospace";
988
989	/// The body / UI slot. Everything that is not the mono slot or brand tier.
990	pub const FONT_SANS: &str = "\"Quasi Body\", sans-serif";
991
992	/// The family name inside [`FONT_MONO`], on its own, for a consumer that needs
993	/// the name rather than the stack. A test asserts the two agree.
994	pub const HOUSE_MONO_FAMILY: &str = "Quasi Mono";
995
996	/// The family name inside [`FONT_SANS`]. See [`HOUSE_MONO_FAMILY`].
997	pub const HOUSE_SANS_FAMILY: &str = "Quasi Body";
998
999	/// The weight range both house faces carry.
1000	///
1001	/// They are variable, `wght` 200-800, and a declaration that omits the range
1002	/// makes every weight resolve to the file's default instance — which is
1003	/// ExtraLight, because a cut keeps its base's default.
1004	pub const HOUSE_WEIGHT_RANGE: &str = "200 800";
1005
1006	/// Filename a consumer writes the cut mono face to, under its own font URL.
1007	///
1008	/// `quasi-type` writes `QuasiMono[wght].woff2`, naming the variable axis the
1009	/// way a font tool expects. Those brackets have to be percent-encoded to
1010	/// survive a URL and are a bug waiting to be written, so the web copy takes a
1011	/// plain name and the two places that have to agree — the build script that
1012	/// writes the file and the `@font-face` that fetches it — agree through this
1013	/// constant rather than by both spelling it out.
1014	pub const WEBFONT_MONO_FILE: &str = "QuasiMono.woff2";
1015
1016	/// Filename a consumer writes the cut body face to. See [`WEBFONT_MONO_FILE`].
1017	pub const WEBFONT_SANS_FILE: &str = "QuasiBody.woff2";
1018
1019	/// The house font tokens as CSS declarations (no selector), for a caller that
1020	/// is composing its own block.
1021	pub fn typography_css_declarations() -> String {
1022	format!(" --font-mono: {FONT_MONO};\n --font-sans: {FONT_SANS};\n")
1023	}
1024
1025	/// The house font tokens as a `:root { … }` block.
1026	///
1027	/// Inlined by surfaces that cannot link a stylesheet — the MNW embeds are the
1028	/// live case — and written to a file by everything else, through
1029	/// `makeover_build::typography_css`.
1030	pub fn typography_css_vars() -> String {
1031	format!(":root {{\n{}}}\n", typography_css_declarations())
1032	}
1033
1034	/// The `@font-face` rules for both slots, fetching from `base_url`.
1035	///
1036	/// `base_url` is the directory the consumer serves its fonts from, without a
1037	/// trailing slash: `/static/fonts` on the MNW server, `fonts` for a Tauri
1038	/// frontend loading relative to its index.
1039	///
1040	/// # `font-weight: 200 800`, which is the part that bites
1041	///
1042	/// Both faces are variable over `wght` 200-800 in one file, and the mono
1043	/// face's default instance is ExtraLight — that is upstream Atkinson's
1044	/// default and the cut keeps the axis rather than pinning a master, so a
1045	/// consumer that loads the file and takes what it opens at draws its whole UI
1046	/// at 200. Declaring the range here is what makes the browser resolve `normal`
1047	/// to 400 and `bold` to 700 instead. shop hit the same trap from the other
1048	/// side and names `wght` 400 explicitly in its shaper; this is the web's
1049	/// version of that fix, stated once for every consumer.
1050	///
1051	/// `font-display: swap` on both: the faces are 31KB and 50KB, they are cached
1052	/// hard after the first paint, and a flash of the fallback beats invisible
1053	/// text either way.
1054	pub fn font_face_css(base_url: &str) -> String {
1055	// Rendered from the same `FontFace` a product override uses, rather than
1056	// written out here a second time. It used to be a format string, which is
1057	// why the house tier could be emitted and not read.
1058	let base = base_url.trim_end_matches('/');
1059	FontSlot::ALL
1060	.iter()
1061	.filter_map(\|slot\| slot.house_face())
1062	.map(\|face\| face.css(base))
1063	.collect()
1064	}
1065
1066	// ============================================================================
1067	// Typography — layer 0, the app override.
1068	//
1069	// Wiki `typography-standard`, GO makeover `174ab3c1`. Layer 1 above is what
1070	// every product shares; this is the one declaration a product is allowed to
1071	// make for itself:
1072	//
1073	// layer 0 app override per product, optional MNW display -> Young Serif
1074	// layer 1 house default the quasi-* slot font quasi-mono -> Quasi Mono
1075	// layer 2 system generic one hop, no further monospace / sans-serif
1076	//
1077	// The brand tier was already exempt by decision (`cdf8ac09`), and the exemption
1078	// was enforced by those faces simply not being in the vocabulary — so each
1079	// product reached its own face through a hardcoded `font-family` and an
1080	// `@font-face` block it maintained by hand, which is the exact shape the
1081	// unification is deleting everywhere else. This turns the carve-out into a
1082	// mechanism: the per-product face is declared once, in the build script that
1083	// already writes the typography layer, and is readable as an override rather
1084	// than as a stylesheet nobody unified.
1085	//
1086	// It permits overriding `mono` and `sans` too. No product wants that today,
1087	// and a layer that only allows overriding the slot nobody describes is not a
1088	// layer, it is the exemption restated.
1089	//
1090	// One declaration per product per slot. [`Typography::with_override`]
1091	// panics on a second override of the same slot rather than letting the last
1092	// one win: a product with two answers for a slot has the vocabulary wrong, and
1093	// that is the thing to fix.
1094	//
1095	// # What a renderer does when it cannot honour one
1096	//
1097	// Declare once, renderers honour what they can. Today only the webview surface
1098	// has a face to honour at all — neither `makeover-tui` nor `makeover-immediate`
1099	// emits a `font-family` from anywhere, because the terminal owns the face in
1100	// one and the app loads its own font stack in the other. So an override is
1101	// honoured by the generated stylesheet and ignored, silently and correctly, by
1102	// the other two. That last clause was too strong and 2.10.0 corrected it: egui
1103	// can reach a face perfectly well, it just needs the file rather than a stack.
1104	// audiofiles honours its override with no stylesheet anywhere in the path. A renderer that gains font control later reads
1105	// [`Typography::resolve`] rather than the CSS, which is why the resolution is
1106	// a method on the data and not a string-building detail. Loading a file needs
1107	// one thing more than the stack — the family name and the source to load it
1108	// from — so [`Typography::faces`] is the same data read the other way, and
1109	// between them an egui or TUI surface can honour an override without a
1110	// stylesheet anywhere in the path. audiofiles is the first to do it.
1111	// ============================================================================
1112
1113	/// A slot in the house font vocabulary — the unit an override replaces.
1114	///
1115	/// Three, and the third is deliberately empty by default: `display` is the
1116	/// brand tier, it has no house answer, and a product that does not override it
1117	/// leaves the token undefined so whatever the consumer wrote as a fallback
1118	/// renders. The MNW embeds rely on exactly that.
1119	#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1120	pub enum FontSlot {
1121	/// Code, data, identifiers, cell grids. [`FONT_MONO`] by default.
1122	Mono,
1123	/// Body and UI text: everything that is not mono or brand. [`FONT_SANS`].
1124	Sans,
1125	/// The brand / display tier. No house default, per `cdf8ac09`.
1126	Display,
1127	}
1128
1129	impl FontSlot {
1130	/// Every slot, in the order they are emitted.
1131	pub const ALL: [FontSlot; 3] = [FontSlot::Mono, FontSlot::Sans, FontSlot::Display];
1132
1133	/// The custom property this slot is read through.
1134	pub fn token(self) -> &'static str {
1135	match self {
1136	FontSlot::Mono => "--font-mono",
1137	FontSlot::Sans => "--font-sans",
1138	FontSlot::Display => "--font-display",
1139	}
1140	}
1141
1142	/// The house stack, or `None` for the brand tier.
1143	pub fn house_default(self) -> Option<&'static str> {
1144	match self {
1145	FontSlot::Mono => Some(FONT_MONO),
1146	FontSlot::Sans => Some(FONT_SANS),
1147	FontSlot::Display => None,
1148	}
1149	}
1150
1151	/// The house face behind that stack, or `None` for the brand tier.
1152	///
1153	/// The counterpart of [`house_default`](Self::house_default), and the same
1154	/// split as [`Typography::resolve`] against [`Typography::faces`]: one
1155	/// names the family that wins, the other names the file behind it. The
1156	/// house tier was a format string until this existed, so it could be
1157	/// emitted and not read — which made [`Typography::faces`] answer for the
1158	/// brand tier and stay silent about the other two.
1159	///
1160	/// The sources are the web copies, and that is the whole of what the
1161	/// house tier ships today. A renderer loading a face directly wants a
1162	/// `ttf`, and there is no house `ttf` under any name to hand it.
1163	pub fn house_face(self) -> Option<FontFace> {
1164	let (family, file) = match self {
1165	FontSlot::Mono => (HOUSE_MONO_FAMILY, WEBFONT_MONO_FILE),
1166	FontSlot::Sans => (HOUSE_SANS_FAMILY, WEBFONT_SANS_FILE),
1167	FontSlot::Display => return None,
1168	};
1169	Some(
1170	FontFace::new(family, [file])
1171	.with_weight(HOUSE_WEIGHT_RANGE)
1172	.with_style("normal"),
1173	)
1174	}
1175	}
1176
1177	/// One `@font-face` an override brings with it.
1178	///
1179	/// A product overriding a slot usually has to ship the face too, and the two
1180	/// halves have to agree on a family name. Declaring them together is what
1181	/// makes that agreement structural rather than a string typed twice.
1182	#[derive(Debug, Clone)]
1183	pub struct FontFace {
1184	family: String,
1185	sources: Vec<String>,
1186	weight: Option<String>,
1187	style: Option<String>,
1188	}
1189
1190	impl FontFace {
1191	/// A face named `family`, fetched from `sources`.
1192	///
1193	/// Each source is either a bare filename, resolved against the
1194	/// [`Typography`] base URL, or an absolute one (`/…` or `https://…`) taken
1195	/// as written. The `format()` hint is inferred from the extension —
1196	/// `woff2`, `woff`, `ttf`, `otf` — and omitted for anything else rather
1197	/// than guessed, since a wrong hint is worse than none.
1198	pub fn new<S: Into<String>>(
1199	family: impl Into<String>,
1200	sources: impl IntoIterator<Item = S>,
1201	) -> Self {
1202	Self {
1203	family: family.into(),
1204	sources: sources.into_iter().map(Into::into).collect(),
1205	weight: None,
1206	style: None,
1207	}
1208	}
1209
1210	/// `font-weight`, as CSS writes it: `"700"`, or `"200 800"` for a variable
1211	/// axis. Omitted when unset, which means `normal`.
1212	///
1213	/// A variable face MUST name its range here for the same reason the house
1214	/// faces do: a `@font-face` with no range makes the browser resolve every
1215	/// weight to the file's default instance.
1216	#[must_use]
1217	pub fn with_weight(mut self, weight: impl Into<String>) -> Self {
1218	self.weight = Some(weight.into());
1219	self
1220	}
1221
1222	/// `font-style`. Omitted when unset, which means `normal`.
1223	#[must_use]
1224	pub fn with_style(mut self, style: impl Into<String>) -> Self {
1225	self.style = Some(style.into());
1226	self
1227	}
1228
1229	/// The declared `font-weight`, or `None` when the face never named one.
1230	///
1231	/// A renderer loading a variable face directly has to name a weight — the
1232	/// file's own default instance is whatever the base shipped, which for the
1233	/// house faces is ExtraLight — so this is the half of the declaration that
1234	/// stops the load from being a guess.
1235	pub fn weight(&self) -> Option<&str> {
1236	self.weight.as_deref()
1237	}
1238
1239	/// The declared `font-style`, or `None`, which means `normal`.
1240	pub fn style(&self) -> Option<&str> {
1241	self.style.as_deref()
1242	}
1243
1244	/// The family name, as the stack has to spell it.
1245	///
1246	/// For a renderer that loads faces rather than emitting CSS this is the
1247	/// name it registers the file under, and reading it here is what keeps
1248	/// that name from being typed a second time.
1249	pub fn family(&self) -> &str {
1250	&self.family
1251	}
1252
1253	/// The sources, unresolved — bare filenames as they were declared, not
1254	/// joined to any base URL. A renderer loading from disk or from an
1255	/// `include_bytes!` wants the filename; only the CSS wants the URL.
1256	pub fn sources(&self) -> &[String] {
1257	&self.sources
1258	}
1259
1260	fn css(&self, base: &str) -> String {
1261	use std::fmt::Write as _;
1262
1263	let src = self
1264	.sources
1265	.iter()
1266	.map(\|s\| {
1267	let url = if s.starts_with('/') \|\| s.contains("://") {
1268	s.clone()
1269	} else {
1270	format!("{base}/{s}")
1271	};
1272	match font_format(s) {
1273	Some(fmt) => format!("url(\"{url}\") format(\"{fmt}\")"),
1274	None => format!("url(\"{url}\")"),
1275	}
1276	})
1277	.collect::<Vec<_>>()
1278	.join(",\n ");
1279
1280	let mut out = format!(
1281	"@font-face {{\n font-family: \"{}\";\n src: {src};\n",
1282	self.family
1283	);
1284	if let Some(w) = &self.weight {
1285	let _ = writeln!(out, " font-weight: {w};");
1286	}
1287	if let Some(s) = &self.style {
1288	let _ = writeln!(out, " font-style: {s};");
1289	}
1290	out.push_str(" font-display: swap;\n}\n\n");
1291	out
1292	}
1293	}
1294
1295	/// The `format()` hint for a source, by extension. `None` when unrecognised.
1296	fn font_format(source: &str) -> Option<&'static str> {
1297	match source.rsplit('.').next()?.to_ascii_lowercase().as_str() {
1298	"woff2" => Some("woff2"),
1299	"woff" => Some("woff"),
1300	"ttf" => Some("truetype"),
1301	"otf" => Some("opentype"),
1302	_ => None,
1303	}
1304	}
1305
1306	/// One product's answer for one slot: the stack, and any faces it ships.
1307	#[derive(Debug, Clone)]
1308	pub struct FontOverride {
1309	slot: FontSlot,
1310	stack: String,
1311	faces: Vec<FontFace>,
1312	}
1313
1314	impl FontOverride {
1315	/// Point `slot` at `stack`.
1316	///
1317	/// `stack` is the CSS value the token takes, written the way the house
1318	/// stacks are: the family, then one hop to a system generic. Layer 2 is
1319	/// still one hop and no further — an override is a different answer to the
1320	/// slot, not a licence to write the fallback chain the standard deleted.
1321	pub fn new(slot: FontSlot, stack: impl Into<String>) -> Self {
1322	Self {
1323	slot,
1324	stack: stack.into(),
1325	faces: Vec::new(),
1326	}
1327	}
1328
1329	/// Ship a face with the override.
1330	#[must_use]
1331	pub fn with_face(mut self, face: FontFace) -> Self {
1332	self.faces.push(face);
1333	self
1334	}
1335
1336	/// The slot this answers.
1337	pub fn slot(&self) -> FontSlot {
1338	self.slot
1339	}
1340
1341	/// The stack it resolves to.
1342	pub fn stack(&self) -> &str {
1343	&self.stack
1344	}
1345
1346	/// The faces it ships, in declaration order.
1347	pub fn faces(&self) -> &[FontFace] {
1348	&self.faces
1349	}
1350	}
1351
1352	/// The whole typography layer for one product: the house defaults, plus
1353	/// whatever it overrides.
1354	///
1355	/// This is what a build script composes and what
1356	/// `makeover_build::typography_css_from` writes. [`typography_css_vars`] and
1357	/// [`font_face_css`] are the no-override case of it and stay for callers that
1358	/// have nothing to declare.
1359	#[derive(Debug, Clone)]
1360	pub struct Typography {
1361	base_url: String,
1362	overrides: Vec<FontOverride>,
1363	}
1364
1365	impl Typography {
1366	/// The house layer alone, fetching faces from `base_url` — the directory
1367	/// the consumer serves fonts from, with or without a trailing slash.
1368	pub fn house(base_url: impl Into<String>) -> Self {
1369	Self {
1370	base_url: base_url.into(),
1371	overrides: Vec::new(),
1372	}
1373	}
1374
1375	/// Add one product override.
1376	///
1377	/// # Panics
1378	///
1379	/// If the slot is already overridden. One declaration per product per
1380	/// slot: a second is not a merge to resolve, it is two answers to a
1381	/// question that has one, and the vocabulary is what wants fixing.
1382	#[must_use]
1383	pub fn with_override(mut self, ov: FontOverride) -> Self {
1384	assert!(
1385	!self.overrides.iter().any(\|o\| o.slot == ov.slot),
1386	"{} is overridden twice; one declaration per product per slot",
1387	ov.slot.token()
1388	);
1389	self.overrides.push(ov);
1390	self
1391	}
1392
1393	/// What `slot` resolves to under this layer, or `None` for a brand slot
1394	/// nobody overrode.
1395	///
1396	/// The resolution, for a renderer that has a face to choose rather than a
1397	/// stylesheet to emit.
1398	pub fn resolve(&self, slot: FontSlot) -> Option<&str> {
1399	self.overrides
1400	.iter()
1401	.find(\|o\| o.slot == slot)
1402	.map(\|o\| o.stack.as_str())
1403	.or_else(\|\| slot.house_default())
1404	}
1405
1406	/// The faces a product ships for `slot`, in declaration order, or an
1407	/// empty slice for a slot it did not override.
1408	///
1409	/// The other half of [`resolve`](Self::resolve), for a renderer that has
1410	/// to load a file rather than name a stack: `resolve` says which family
1411	/// wins, this says where the bytes come from, what to call them, and at
1412	/// what weight. The
1413	/// house faces are not here — they belong to the slot rather than to any
1414	/// one product, and [`FontSlot::house_face`] is where they answer.
1415	pub fn faces(&self, slot: FontSlot) -> &[FontFace] {
1416	self.overrides
1417	.iter()
1418	.find(\|o\| o.slot == slot)
1419	.map_or(&[], \|o\| o.faces())
1420	}
1421
1422	/// The `@font-face` rules: the two house faces, then each override's.
1423	pub fn font_face_css(&self) -> String {
1424	let base = self.base_url.trim_end_matches('/');
1425	let mut out = font_face_css(base);
1426	for ov in &self.overrides {
1427	for face in &ov.faces {
1428	out.push_str(&face.css(base));
1429	}
1430	}
1431	out
1432	}
1433
1434	/// The resolved tokens as CSS declarations, no selector.
1435	pub fn css_declarations(&self) -> String {
1436	use std::fmt::Write as _;
1437
1438	let mut out = String::new();
1439	for slot in FontSlot::ALL {
1440	if let Some(stack) = self.resolve(slot) {
1441	let _ = writeln!(out, " {}: {stack};", slot.token());
1442	}
1443	}
1444	out
1445	}
1446
1447	/// The resolved tokens as a `:root { … }` block.
1448	pub fn css_vars(&self) -> String {
1449	format!(":root {{\n{}}}\n", self.css_declarations())
1450	}
1451
1452	/// Faces then tokens, in the order a stylesheet wants them.
1453	pub fn css(&self) -> String {
1454	format!("{}{}", self.font_face_css(), self.css_vars())
1455	}
1456	}
1457
1458	// ============================================================================
1459	// Loading / parsing
1460	// ============================================================================
1461
1462	/// Validate a theme ID contains only safe characters (alphanumeric, hyphens, underscores).
1463	pub fn validate_theme_id(id: &str) -> Result<(), String> {
1464	if !id
1465	.chars()
1466	.all(\|c\| c.is_alphanumeric() \|\| c == '-' \|\| c == '_')
1467	{
1468	return Err(format!("Invalid theme ID: {id}"));
1469	}
1470	Ok(())
1471	}
1472
1473	/// Parse the `[meta]` section into `ThemeMeta`.
1474	///
1475	/// Falls back to the file ID as the name and `"dark"` as the variant.
1476	pub fn parse_meta(id: &str, table: &toml::Table, is_custom: bool) -> ThemeMeta {
1477	let meta = table.get("meta").and_then(\|m\| m.as_table());
1478	let name = meta
1479	.and_then(\|m\| m.get("name"))
1480	.and_then(\|v\| v.as_str())
1481	.unwrap_or(id)
1482	.to_string();
1483	let variant = meta
1484	.and_then(\|m\| m.get("variant"))
1485	.and_then(\|v\| v.as_str())
1486	.unwrap_or("dark")
1487	.to_string();
1488
1489	ThemeMeta {
1490	id: id.to_string(),
1491	name,
1492	variant,
1493	is_custom,
1494	}
1495	}
1496
1497	// ============================================================================
1498	// Choosing a theme.
1499	//
1500	// The file half of this crate was always shared; the selection half was not,
1501	// and four apps re-rolled it four ways. GoingsOn stores a "system" sentinel in
1502	// localStorage, Balanced Breakfast treats an absent value as follow-the-system
1503	// and hardcodes two theme ids as its light/dark pair, audiofiles keeps the id
1504	// in a synced SQLite table, and the Alloy console parses COLORFGBG. They also
1505	// disagreed about what a variant string means: this crate defaults a missing
1506	// one to "dark" while alloy_tui parsed an unrecognized one as light.
1507	//
1508	// What cannot be shared is the store — localStorage, a synced config table and
1509	// a TOML file are genuinely different places. What can be shared, and is here,
1510	// is the meaning: one vocabulary for variants, one encoding for "what did the
1511	// user choose", and one rule for turning that into an id that exists.
1512	// ============================================================================
1513
1514	/// A theme's kind, as declared by `meta.variant`.
1515	///
1516	/// Three, not two: one shipped theme is `high-contrast`, and an app that
1517	/// matched on light-or-dark alone would quietly file it under the wrong one.
1518	#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize)]
1519	#[serde(rename_all = "kebab-case")]
1520	pub enum Variant {
1521	Light,
1522	Dark,
1523	HighContrast,
1524	}
1525
1526	impl Variant {
1527	/// The spelling used in a theme file and in [`ThemeMeta::variant`].
1528	#[must_use]
1529	pub const fn as_str(self) -> &'static str {
1530	match self {
1531	Variant::Light => "light",
1532	Variant::Dark => "dark",
1533	Variant::HighContrast => "high-contrast",
1534	}
1535	}
1536
1537	/// Read a variant string, or `None` if it names none of them.
1538	#[must_use]
1539	pub fn parse(raw: &str) -> Option<Self> {
1540	match raw {
1541	"light" => Some(Variant::Light),
1542	"dark" => Some(Variant::Dark),
1543	"high-contrast" => Some(Variant::HighContrast),
1544	_ => None,
1545	}
1546	}
1547	}
1548
1549	impl std::fmt::Display for Variant {
1550	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
1551	f.write_str(self.as_str())
1552	}
1553	}
1554
1555	/// Anything unrecognized reads as dark, which is what [`parse_meta`] already
1556	/// does with a missing one. Consumers that guessed light for an unknown string
1557	/// were disagreeing with the crate that produced it.
1558	impl From<&str> for Variant {
1559	fn from(raw: &str) -> Self {
1560	Variant::parse(raw).unwrap_or(Variant::Dark)
1561	}
1562	}
1563
1564	impl ThemeMeta {
1565	/// This theme's variant as a value rather than a string.
1566	#[must_use]
1567	pub fn kind(&self) -> Variant {
1568	Variant::from(self.variant.as_str())
1569	}
1570	}
1571
1572	/// The spelling of "follow whatever the system is doing", in every store.
1573	pub const FOLLOW: &str = "system";
1574
1575	/// What the user chose, as opposed to what is being rendered.
1576	///
1577	/// The distinction is the whole point: `Follow` is a standing instruction that
1578	/// resolves differently as the ambient mode changes, and a `Fixed` id is an
1579	/// answer that does not. An app that stored only the rendered id could not tell
1580	/// the two apart the next time the system flipped to dark.
1581	#[derive(Debug, Clone, PartialEq, Eq, Default)]
1582	pub enum ThemeSelection {
1583	/// Track the ambient light/dark mode.
1584	#[default]
1585	Follow,
1586	/// Always this theme.
1587	Fixed(String),
1588	}
1589
1590	impl ThemeSelection {
1591	/// Read a stored selection. An empty or absent value is [`Follow`], which
1592	/// is what an app with nothing saved yet should do.
1593	///
1594	/// [`Follow`]: ThemeSelection::Follow
1595	#[must_use]
1596	pub fn parse(raw: Option<&str>) -> Self {
1597	match raw.map(str::trim) {
1598	None \| Some("" \| FOLLOW) => ThemeSelection::Follow,
1599	Some(id) => ThemeSelection::Fixed(id.to_string()),
1600	}
1601	}
1602
1603	/// The string to persist, whatever the store is.
1604	#[must_use]
1605	pub fn as_str(&self) -> &str {
1606	match self {
1607	ThemeSelection::Follow => FOLLOW,
1608	ThemeSelection::Fixed(id) => id,
1609	}
1610	}
1611
1612	/// Turn a selection into a theme id that exists.
1613	///
1614	/// `ambient` is the light/dark mode the app learned however it can: a
1615	/// `prefers-color-scheme` media query, an OS appearance API, `COLORFGBG`
1616	/// from a terminal. `available` is what [`list_themes_from_dirs`] found.
1617	///
1618	/// A `Fixed` id that is no longer on disk falls through to the same path as
1619	/// `Follow` rather than being returned anyway. Themes are deletable in
1620	/// three of the four apps, and handing back an id that will fail to load
1621	/// only moves the error somewhere less helpful.
1622	///
1623	/// The fallback chain is: the app's own default for the ambient mode if it
1624	/// is installed, then any installed theme of that variant, then the app's
1625	/// default regardless. The last step means this always returns something,
1626	/// and an app with no theme directory at all gets the id it ships with and
1627	/// the load error it would have had anyway.
1628	#[must_use]
1629	pub fn resolve(
1630	&self,
1631	ambient: Variant,
1632	defaults: &ThemeDefaults,
1633	available: &[ThemeMeta],
1634	) -> String {
1635	let installed = \|id: &str\| available.iter().any(\|meta\| meta.id == id);
1636
1637	if let ThemeSelection::Fixed(id) = self
1638	&& installed(id)
1639	{
1640	return id.clone();
1641	}
1642
1643	let preferred = defaults.for_variant(ambient);
1644	if installed(preferred) {
1645	return preferred.to_string();
1646	}
1647	available
1648	.iter()
1649	.find(\|meta\| meta.kind() == ambient)
1650	.map_or_else(\|\| preferred.to_string(), \|meta\| meta.id.clone())
1651	}
1652	}
1653
1654	impl std::fmt::Display for ThemeSelection {
1655	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
1656	f.write_str(self.as_str())
1657	}
1658	}
1659
1660	/// The themes an app falls back to, one per ambient mode.
1661	///
1662	/// App-specific on purpose: which theme is "the app's own" is the app's
1663	/// identity, not this crate's business. What is shared is everything around it.
1664	#[derive(Debug, Clone)]
1665	pub struct ThemeDefaults {
1666	light: String,
1667	dark: String,
1668	high_contrast: Option<String>,
1669	}
1670
1671	impl ThemeDefaults {
1672	pub fn new(light: impl Into<String>, dark: impl Into<String>) -> Self {
1673	Self {
1674	light: light.into(),
1675	dark: dark.into(),
1676	high_contrast: None,
1677	}
1678	}
1679
1680	/// Name a theme for a high-contrast ambient mode. Without one, that mode
1681	/// falls back to the dark default, which is the safer of the two to read.
1682	#[must_use]
1683	pub fn high_contrast(mut self, id: impl Into<String>) -> Self {
1684	self.high_contrast = Some(id.into());
1685	self
1686	}
1687
1688	#[must_use]
1689	pub fn for_variant(&self, variant: Variant) -> &str {
1690	match variant {
1691	Variant::Light => &self.light,
1692	Variant::Dark => &self.dark,
1693	Variant::HighContrast => self.high_contrast.as_ref().unwrap_or(&self.dark),
1694	}
1695	}
1696	}
1697
1698	// ============================================================================
1699	// Where themes are looked for.
1700	//
1701	// Four apps built this vector by hand, two of them byte-for-byte identically,
1702	// and one of them built it backwards: the Alloy console pushed the user's own
1703	// directory first, under a comment saying "highest precedence first", when both
1704	// consumers of the vector resolve last wins. A user's custom theme lost to
1705	// the packaged one of the same id.
1706	//
1707	// Hence a builder that names the tiers rather than a function taking a vector.
1708	// The precedence is stated once, here, and a caller cannot express it backwards
1709	// because the order is not theirs to choose.
1710	// ============================================================================
1711
1712	/// Builds the search path [`load_theme`] and [`list_themes_from_dirs`] take.
1713	///
1714	/// Tiers are added in whatever order is convenient and always end up in
1715	/// precedence order: the user's own themes win, then whatever the system
1716	/// ships, then whatever the app bundles.
1717	///
1718	/// A directory that does not exist is dropped rather than carried, so callers
1719	/// can offer every tier they might have without checking each one.
1720	#[derive(Debug, Default, Clone)]
1721	pub struct ThemeDirs {
1722	bundled: Vec<PathBuf>,
1723	system: Vec<PathBuf>,
1724	custom: Option<PathBuf>,
1725	}
1726
1727	impl ThemeDirs {
1728	#[must_use]
1729	pub fn new() -> Self {
1730	Self::default()
1731	}
1732
1733	/// Themes the app ships with. Lowest precedence.
1734	///
1735	/// Takes more than one because a Tauri app has two: the bundled resource
1736	/// directory in production, and the tree `build.rs` materialized for a
1737	/// `cargo run` that has no resource directory at all.
1738	#[must_use]
1739	pub fn bundled(mut self, dir: Option<PathBuf>) -> Self {
1740	self.bundled.extend(dir);
1741	self
1742	}
1743
1744	/// Themes the machine ships, from an image or a package. Overrides bundled.
1745	#[must_use]
1746	pub fn system(mut self, dir: Option<PathBuf>) -> Self {
1747	self.system.extend(dir);
1748	self
1749	}
1750
1751	/// The user's own themes. Highest precedence, and the only tier flagged
1752	/// custom, which is what makes them exportable and deletable.
1753	#[must_use]
1754	pub fn custom(mut self, dir: Option<PathBuf>) -> Self {
1755	self.custom = dir;
1756	self
1757	}
1758
1759	/// The search path, lowest precedence first.
1760	#[must_use]
1761	pub fn build(self) -> Vec<(PathBuf, bool)> {
1762	let mut dirs = Vec::new();
1763	for dir in self.bundled.into_iter().chain(self.system) {
1764	if dir.is_dir() {
1765	dirs.push((dir, false));
1766	}
1767	}
1768	if let Some(dir) = self.custom
1769	&& dir.is_dir()
1770	{
1771	dirs.push((dir, true));
1772	}
1773	dirs
1774	}
1775	}
1776
1777	/// Extract the intent color sections into a flat `HashMap` with dotted keys
1778	/// like `"surface.page"`, `"status.danger"`, `"category.one"`.
1779	///
1780	/// The tonal steps of `content.primary` are filled in here rather than read, by
1781	/// [`derive_tonal_steps`]. Anything a theme authored under those keys is
1782	/// replaced.
1783	pub fn extract_colors(table: &toml::Table) -> HashMap<String, String> {
1784	let mut colors = HashMap::new();
1785	for section in COLOR_SECTIONS {
1786	if let Some(sect) = table.get(*section).and_then(\|s\| s.as_table()) {
1787	for (key, val) in sect {
1788	if let Some(color) = val.as_str() {
1789	colors.insert(format!("{section}.{key}"), color.to_string());
1790	}
1791	}
1792	}
1793	}
1794	derive_tonal_steps(&mut colors);
1795	colors
1796	}
1797
1798	/// Fill in the tonal steps of `content.primary`, overwriting whatever the theme
1799	/// authored under those keys.
1800	///
1801	/// # Why they are not authored
1802	///
1803	/// `content.secondary` and `content.muted` are not independent colours. They are
1804	/// the ink, one step and two steps back, and a theme that names them separately
1805	/// is stating three times something it stated once — which is how three of the
1806	/// bundled themes came to author a `secondary` lighter than their own
1807	/// `primary` (nord, solarized-dark) or identical to it (dracula), inverting the
1808	/// emphasis ramp the whole vocabulary rests on. Deriving them makes
1809	/// `content` > `content-secondary` > `content-muted` true by construction in
1810	/// every theme, including one a user writes.
1811	///
1812	/// Applied at load rather than in [`resolve`] so that there is one answer: the
1813	/// resolved token layer, the ANSI table ([`ansi_intent`] reads authored keys),
1814	/// and every consumer holding a [`ThemeColors`] all see the same value. A
1815	/// derivation visible from only one of those is how a terminal and a webview
1816	/// come to disagree about what muted means.
1817	///
1818	/// Both keys need `content.primary` and `surface.page` to exist and parse. When
1819	/// either is missing the step is skipped and anything authored is left where it
1820	/// is, mirroring the skip-missing behaviour of the rest of the crate — a
1821	/// half-written theme keeps whatever it has rather than losing it.
1822	///
1823	/// # The ratio is a starting point, not the answer
1824	///
1825	/// Each step is pushed further toward the page until it clears [`STEP_FLOOR`]
1826	/// against the ink, so what the theme gets is a step that can be seen rather
1827	/// than a step of the agreed size. The two are the same number in every bundled
1828	/// theme but the two with a pure-black ink, where the ratio has no range to
1829	/// travel in and the nominal step lands 3/255 from where it started.
1830	pub fn derive_tonal_steps<S: std::hash::BuildHasher>(colors: &mut HashMap<String, String, S>) {
1831	let ink = colors.get("content.primary").and_then(\|v\| Rgb::from_hex(v));
1832	let page = colors.get("surface.page").and_then(\|v\| Rgb::from_hex(v));
1833	let (Some(ink), Some(page)) = (ink, page) else {
1834	return;
1835	};
1836	// Each step starts no nearer than the one before it landed, so pushing
1837	// secondary out cannot carry it past muted and invert the ramp.
1838	let mut reached = 0.0;
1839	for (key, step) in [
1840	("content.secondary", Emphasis::Secondary),
1841	("content.muted", Emphasis::Muted),
1842	] {
1843	let (color, ratio) = step_clearing_floor(ink, page, step.ratio().max(reached));
1844	reached = ratio;
1845	colors.insert(key.to_string(), color.to_hex());
1846	}
1847	}
1848
1849	/// The step `from` of the way from `ink` to `page`, pushed toward `page` until
1850	/// it clears [`STEP_FLOOR`] against the ink it is a step of. Returns the colour
1851	/// and the ratio it was found at.
1852	///
1853	/// A forward scan rather than a solve, because it wants the first ratio that
1854	/// clears: contrast against the base rises with the distance travelled, but it
1855	/// rises through sRGB's transfer curve and OKLab's chroma path, and a bisection
1856	/// would trust a monotonicity nothing here guarantees.
1857	///
1858	/// Travel stops at the ground. A theme whose ink and page are the same colour
1859	/// has no step to take, and the ground is the honest answer — nothing past it
1860	/// is a step of the ink any more.
1861	fn step_clearing_floor(ink: Rgb, page: Rgb, from: f32) -> (Rgb, f32) {
1862	// Finer than 8-bit sRGB can resolve on the shortest ramp in the corpus, so
1863	// the scan never steps over the first colour that clears.
1864	const PROBE: f32 = 0.005;
1865	let mut ratio = from.clamp(0.0, 1.0);
1866	loop {
1867	let color = tonal(ink, page, ratio);
1868	if wcag_contrast(color, ink) >= STEP_FLOOR \|\| ratio >= 1.0 {
1869	return (color, ratio);
1870	}
1871	ratio = (ratio + PROBE).min(1.0);
1872	}
1873	}
1874
1875	/// Scan directories for `.toml` theme files and return metadata for each.
1876	///
1877	/// Directories are checked in order; later entries override earlier ones by ID.
1878	/// Each entry in `dirs` is `(path, is_custom)`.
1879	pub fn list_themes_from_dirs(dirs: &[(PathBuf, bool)]) -> Vec<ThemeMeta> {
1880	let mut seen: HashMap<String, ThemeMeta> = HashMap::new();
1881
1882	for (dir, is_custom) in dirs {
1883	let Ok(entries) = std::fs::read_dir(dir) else {
1884	continue;
1885	};
1886
1887	for entry in entries {
1888	let Ok(entry) = entry else {
1889	continue;
1890	};
1891	let path = entry.path();
1892	if path.extension().and_then(\|e\| e.to_str()) != Some("toml") {
1893	continue;
1894	}
1895
1896	let id = path
1897	.file_stem()
1898	.and_then(\|s\| s.to_str())
1899	.unwrap_or_default()
1900	.to_string();
1901
1902	let Ok(content) = std::fs::read_to_string(&path) else {
1903	continue;
1904	};
1905	let table: toml::Table = match content.parse() {
1906	Ok(t) => t,
1907	Err(_) => continue,
1908	};
1909
1910	seen.insert(id.clone(), parse_meta(&id, &table, *is_custom));
1911	}
1912	}
1913
1914	let mut themes: Vec<ThemeMeta> = seen.into_values().collect();
1915	themes.sort_by(\|a, b\| a.name.cmp(&b.name));
1916	themes
1917	}
1918
1919	/// Find a theme file by ID in the given directories.
1920	///
1921	/// Checks directories in reverse order so the highest-priority directory wins.
1922	/// Returns `(path, is_custom)` or `None` if not found.
1923	pub fn find_theme_path(dirs: &[(PathBuf, bool)], id: &str) -> Option<(PathBuf, bool)> {
1924	let filename = format!("{id}.toml");
1925
1926	for (dir, is_custom) in dirs.iter().rev() {
1927	let path = dir.join(&filename);
1928	if path.is_file() {
1929	return Some((path, *is_custom));
1930	}
1931	}
1932
1933	None
1934	}
1935
1936	/// Parse a complete theme (metadata + colors) from raw TOML content, with no
1937	/// filesystem access. For callers that embed themes at compile time.
1938	pub fn parse_theme_str(id: &str, content: &str, is_custom: bool) -> Result<ThemeColors, String> {
1939	validate_theme_id(id)?;
1940	let table: toml::Table = content
1941	.parse()
1942	.map_err(\|e\| format!("Failed to parse theme '{id}': {e}"))?;
1943	let meta = parse_meta(id, &table, is_custom);
1944	let colors = extract_colors(&table);
1945	Ok(ThemeColors { meta, colors })
1946	}
1947
1948	/// Load a complete theme (metadata + colors) by ID from the given directories.
1949	pub fn load_theme(dirs: &[(PathBuf, bool)], id: &str) -> Result<ThemeColors, String> {
1950	validate_theme_id(id)?;
1951
1952	let (path, is_custom) =
1953	find_theme_path(dirs, id).ok_or_else(\|\| format!("Theme '{id}' not found"))?;
1954
1955	let content = std::fs::read_to_string(&path)
1956	.map_err(\|e\| format!("Failed to read {}: {}", path.display(), e))?;
1957
1958	let table: toml::Table = content
1959	.parse()
1960	.map_err(\|e\| format!("Failed to parse {}: {}", path.display(), e))?;
1961
1962	let meta = parse_meta(id, &table, is_custom);
1963	let colors = extract_colors(&table);
1964
1965	Ok(ThemeColors { meta, colors })
1966	}
1967
1968	/// Load a theme and resolve it to the full intent token set in one step.
1969	pub fn load_semantic(dirs: &[(PathBuf, bool)], id: &str) -> Result<SemanticTokens, String> {
1970	Ok(resolve(&load_theme(dirs, id)?))
1971	}
1972
1973	/// Import a theme TOML file into the custom themes directory.
1974	///
1975	/// Validates that the file is parseable TOML with at least one intent color
1976	/// section, then copies it to `custom_dir/{id}.toml`. Returns the theme metadata.
1977	pub fn import_theme(source_path: &Path, custom_dir: &Path) -> Result<ThemeMeta, String> {
1978	let content = std::fs::read_to_string(source_path)
1979	.map_err(\|e\| format!("Failed to read {}: {}", source_path.display(), e))?;
1980
1981	let table: toml::Table = content.parse().map_err(\|e\| format!("Invalid TOML: {e}"))?;
1982
1983	let has_colors = COLOR_SECTIONS
1984	.iter()
1985	.any(\|s\| table.get(*s).and_then(\|v\| v.as_table()).is_some());
1986	if !has_colors {
1987	return Err(format!(
1988	"Theme file must have at least one color section ({})",
1989	COLOR_SECTIONS.join(", ")
1990	));
1991	}
1992
1993	let id = source_path
1994	.file_stem()
1995	.and_then(\|s\| s.to_str())
1996	.ok_or("Invalid file name")?
1997	.to_string();
1998	validate_theme_id(&id)?;
1999
2000	std::fs::create_dir_all(custom_dir)
2001	.map_err(\|e\| format!("Failed to create {}: {}", custom_dir.display(), e))?;
2002
2003	let dest = custom_dir.join(format!("{id}.toml"));
2004	std::fs::copy(source_path, &dest).map_err(\|e\| format!("Failed to copy theme: {e}"))?;
2005
2006	Ok(parse_meta(&id, &table, true))
2007	}
2008
2009	/// Delete a custom theme by ID.
2010	///
2011	/// Only operates on `custom_dir` — bundled themes are not deletable through
2012	/// this entry point.
2013	pub fn delete_theme(custom_dir: &Path, id: &str) -> Result<(), String> {
2014	validate_theme_id(id)?;
2015
2016	let path = custom_dir.join(format!("{id}.toml"));
2017	if !path.is_file() {
2018	return Err(format!("Custom theme '{id}' not found"));
2019	}
2020
2021	std::fs::remove_file(&path).map_err(\|e\| format!("Failed to delete {}: {}", path.display(), e))
2022	}
2023
2024	/// A four-color preview for theme thumbnails: the representative swatch from
2025	/// each of the principal roles.
2026	#[derive(Debug, Clone, Serialize)]
2027	#[serde(rename_all = "camelCase")]
2028	pub struct ThemePreview {
2029	pub meta: ThemeMeta,
2030	/// Page background (`surface.page`).
2031	pub background: Option<String>,
2032	/// Body text (`content.primary`).
2033	pub foreground: Option<String>,
2034	/// Brand/interactive color (`action.primary`).
2035	pub accent: Option<String>,
2036	/// Divider/outline color (`line.border`).
2037	pub border: Option<String>,
2038	}
2039
2040	fn color_at(table: &toml::Table, section: &str, key: &str) -> Option<String> {
2041	table
2042	.get(section)
2043	.and_then(\|s\| s.as_table())
2044	.and_then(\|s\| s.get(key))
2045	.and_then(\|v\| v.as_str())
2046	.map(std::string::ToString::to_string)
2047	}
2048
2049	/// Load just the preview swatches for a theme — for UI thumbnails.
2050	pub fn load_theme_preview(dirs: &[(PathBuf, bool)], id: &str) -> Result<ThemePreview, String> {
2051	validate_theme_id(id)?;
2052
2053	let (path, is_custom) =
2054	find_theme_path(dirs, id).ok_or_else(\|\| format!("Theme '{id}' not found"))?;
2055
2056	let content = std::fs::read_to_string(&path)
2057	.map_err(\|e\| format!("Failed to read {}: {}", path.display(), e))?;
2058
2059	let table: toml::Table = content
2060	.parse()
2061	.map_err(\|e\| format!("Failed to parse {}: {}", path.display(), e))?;
2062
2063	Ok(ThemePreview {
2064	meta: parse_meta(id, &table, is_custom),
2065	background: color_at(&table, "surface", "page"),
2066	foreground: color_at(&table, "content", "primary"),
2067	accent: color_at(&table, "action", "primary"),
2068	border: color_at(&table, "line", "border"),
2069	})
2070	}
2071
2072	/// Export a theme to a user-chosen path.
2073	pub fn export_theme(dirs: &[(PathBuf, bool)], id: &str, dest_path: &Path) -> Result<(), String> {
2074	validate_theme_id(id)?;
2075
2076	let (source, _) = find_theme_path(dirs, id).ok_or_else(\|\| format!("Theme '{id}' not found"))?;
2077
2078	std::fs::copy(&source, dest_path).map_err(\|e\| format!("Failed to export theme: {e}"))?;
2079
2080	Ok(())
2081	}
2082
2083	/// The themes this crate ships, embedded at compile time.
2084	///
2085	/// `include_dir` is an implementation detail: the public API hands back plain
2086	/// `(id, toml_source)` pairs, so how the data is embedded can change without
2087	/// a breaking release.
2088	static EMBEDDED: include_dir::Dir<'static> =
2089	include_dir::include_dir!("$CARGO_MANIFEST_DIR/themes");
2090
2091	/// The themes this crate ships, as `(id, toml_source)` pairs.
2092	///
2093	/// This is the path-free way to reach the bundled set, for consumers that
2094	/// cannot rely on a directory existing at runtime: a crate pulled from
2095	/// crates.io lives in a registry checkout whose location is not knowable at
2096	/// compile time, so `include_dir!` and asset-bundling globs in the depending
2097	/// crate have nothing stable to point at. Embedding here and re-exporting the
2098	/// contents gives them one source of truth without a path.
2099	///
2100	/// Ordering follows the embedded directory and is not guaranteed; collect and
2101	/// sort by id where a stable order matters (a theme picker, say).
2102	pub fn embedded_themes() -> impl Iterator<Item = (&'static str, &'static str)> {
2103	EMBEDDED.files().filter_map(\|file\| {
2104	let path = file.path();
2105	if path.extension().and_then(\|e\| e.to_str()) != Some("toml") {
2106	return None;
2107	}
2108	let id = path.file_stem()?.to_str()?;
2109	Some((id, file.contents_utf8()?))
2110	})
2111	}
2112
2113	/// The theme directory this crate ships, for use as a build-from-source
2114	/// fallback.
2115	///
2116	/// Resolves against `makeover`'s own manifest directory, fixed at compile
2117	/// time, so it works from a path dependency and from a cargo git checkout
2118	/// alike. Installed systems should put their packaged theme directory ahead
2119	/// of this in the search path; this is the entry that keeps `cargo run` in a
2120	/// fresh clone from coming up with no themes at all.
2121	///
2122	/// Returns `None` when the directory is absent — a cargo cache that has been
2123	/// cleaned, or a vendored copy that dropped the data — so callers degrade to
2124	/// their remaining search path rather than failing.
2125	pub fn bundled_themes_dir() -> Option<PathBuf> {
2126	let themes = Path::new(env!("CARGO_MANIFEST_DIR")).join("themes");
2127	if themes.is_dir() { Some(themes) } else { None }
2128	}
2129
2130	#[cfg(test)]
2131	mod tests {
2132	use super::*;
2133	use std::fs;
2134
2135	// ---- id validation ----
2136
2137	#[test]
2138	fn validate_theme_id_alphanumeric() {
2139	assert!(validate_theme_id("darkmode").is_ok());
2140	assert!(validate_theme_id("Theme123").is_ok());
2141	}
2142
2143	#[test]
2144	fn validate_theme_id_hyphens_underscores() {
2145	assert!(validate_theme_id("dark-mode").is_ok());
2146	assert!(validate_theme_id("my_theme_v2").is_ok());
2147	}
2148
2149	#[test]
2150	fn validate_theme_id_rejects_path_traversal() {
2151	assert!(validate_theme_id("../etc/passwd").is_err());
2152	assert!(validate_theme_id("foo/bar").is_err());
2153	assert!(validate_theme_id("theme.toml").is_err());
2154	}
2155
2156	// ---- low-color terminals ----
2157
2158	#[test]
2159	fn the_ansi_palette_is_sixteen_distinct_colors() {
2160	let mut seen: Vec<(u8, u8, u8)> = ANSI_16.iter().map(\|c\| c.tuple()).collect();
2161	seen.sort_unstable();
2162	seen.dedup();
2163	assert_eq!(seen.len(), 16);
2164	}
2165
2166	// ---- the intent-to-slot table ----
2167
2168	// Sixteen slots, every one of them answered. A caller filling a terminal
2169	// palette has no fallback for a hole: the slot would keep whatever the
2170	// emulator started with, and one raw ANSI colour in a themed table is more
2171	// obviously wrong than all sixteen would be.
2172	#[test]
2173	fn every_ansi_slot_names_an_intent_on_either_polarity() {
2174	for variant in ["light", "dark", "high-contrast"] {
2175	for index in 0..16 {
2176	assert!(
2177	ansi_intent(index, variant).is_some(),
2178	"slot {index} unanswered on {variant}"
2179	);
2180	}
2181	assert_eq!(ansi_intent(16, variant), None);
2182	}
2183	}
2184
2185	// The property the four achromatic slots exist to hold: 0 is the darkest
2186	// tone the theme offers and 15 the lightest, in either polarity. A table
2187	// that pins slot 0 to `content.primary` passes this on a light theme and
2188	// inverts on a dark one, which is the bug the polarity split fixes.
2189	#[test]
2190	fn ansi_zero_is_darker_than_ansi_fifteen_on_either_polarity() {
2191	for id in ["akari-dawn", "akari-night"] {
2192	let theme = bundled(id);
2193	let slot = \|i: usize\| -> Rgb {
2194	let key = ansi_intent(i, &theme.meta.variant).expect("in range");
2195	Rgb::from_hex(theme.colors.get(key).expect("theme carries it")).expect("valid hex")
2196	};
2197	assert!(
2198	rel_luminance(slot(0)) < rel_luminance(slot(15)),
2199	"{id}: ANSI 0 {} should be darker than ANSI 15 {}",
2200	slot(0).to_hex(),
2201	slot(15).to_hex(),
2202	);
2203	}
2204	}
2205
2206	// The pair a greeter draws with: its container on 7, its text on 0. If
2207	// those collapse the login screen is one flat block, and slot 7 being a
2208	// surface rather than a text tone is what keeps them apart.
2209	#[test]
2210	fn the_container_slot_and_the_text_slot_stay_legible() {
2211	for id in ["akari-dawn", "akari-night"] {
2212	let theme = bundled(id);
2213	let slot = \|i: usize\| -> Rgb {
2214	let key = ansi_intent(i, &theme.meta.variant).expect("in range");
2215	Rgb::from_hex(theme.colors.get(key).expect("theme carries it")).expect("valid hex")
2216	};
2217	let contrast = wcag_contrast(slot(0), slot(7));
2218	assert!(contrast >= 4.5, "{id}: ANSI 0 on ANSI 7 is {contrast:.2}:1");
2219	}
2220	}
2221
2222	// The hues do not move with polarity. Red is the theme's danger tone on a
2223	// light theme and on a dark one, which is why only four slots are in the
2224	// polarity table at all.
2225	#[test]
2226	fn the_chromatic_slots_do_not_vary_with_polarity() {
2227	for index in [1, 2, 3, 4, 5, 6, 9, 10, 11, 12, 13, 14] {
2228	assert_eq!(
2229	ansi_intent(index, "light"),
2230	ansi_intent(index, "dark"),
2231	"slot {index} moved with polarity"
2232	);
2233	}
2234	}
2235
2236	fn bundled(id: &str) -> ThemeColors {
2237	let dir = bundled_themes_dir().expect("makeover ships its themes");
2238	load_theme(&[(dir, false)], id).expect("the akari pair ships")
2239	}
2240
2241	#[test]
2242	fn quantize_picks_the_obvious_entry() {
2243	let black = Rgb { r: 0, g: 0, b: 0 };
2244	let white = Rgb {
2245	r: 255,
2246	g: 255,
2247	b: 255,
2248	};
2249	assert_eq!(quantize(black, &ANSI_16), 0);
2250	assert_eq!(quantize(white, &ANSI_16), 15);
2251	}
2252
2253	// Nearest-entry quantization is per-color, so two colors a theme keeps
2254	// apart can arrive as one. These two are both closest to the palette's
2255	// light gray, and a border drawn in one on a page painted the other is not
2256	// drawn at all.
2257	#[test]
2258	fn two_colors_can_quantize_to_one_entry() {
2259	let page = Rgb::from_hex("#a8a8a8").unwrap();
2260	let border = Rgb::from_hex("#b4b4b4").unwrap();
2261
2262	assert_eq!(quantize(page, &ANSI_16), quantize(border, &ANSI_16));
2263	assert_ne!(
2264	quantize_against(border, page, &ANSI_16),
2265	quantize(page, &ANSI_16)
2266	);
2267	}
2268
2269	#[test]
2270	fn quantize_against_keeps_the_border_off_the_page() {
2271	let page = Rgb::from_hex("#e4ded6").unwrap();
2272	let border = Rgb::from_hex("#7f786d").unwrap();
2273
2274	let shown_page = ANSI_16[quantize(page, &ANSI_16)];
2275	let shown_border = ANSI_16[quantize_against(border, page, &ANSI_16)];
2276
2277	assert!(
2278	wcag_contrast(shown_border, shown_page) >= DISTINCT,
2279	"border {} on page {} is {:.2}:1",
2280	shown_border.to_hex(),
2281	shown_page.to_hex(),
2282	wcag_contrast(shown_border, shown_page)
2283	);
2284	}
2285
2286	// A color that already reads against its background is left where it is,
2287	// so this can be applied without redesigning what already worked.
2288	#[test]
2289	fn quantize_against_leaves_a_readable_color_alone() {
2290	let page = Rgb::from_hex("#e4ded6").unwrap();
2291	let text = Rgb::from_hex("#1a1816").unwrap();
2292
2293	assert_eq!(
2294	quantize_against(text, page, &ANSI_16),
2295	quantize(text, &ANSI_16)
2296	);
2297	}
2298
2299	// With nothing in the palette to satisfy the request, the most legible
2300	// entry is the answer. Returning the nearest one would return the
2301	// background itself, which is the failure this function exists to avoid.
2302	#[test]
2303	fn an_impossible_palette_gets_the_most_legible_entry() {
2304	let page = Rgb::from_hex("#ffffff").unwrap();
2305	let border = Rgb::from_hex("#fefefe").unwrap();
2306	let palette = [
2307	Rgb::from_hex("#ffffff").unwrap(),
2308	Rgb::from_hex("#fdfdfd").unwrap(),
2309	];
2310
2311	let chosen = palette[quantize_against(border, page, &palette)];
2312	assert_eq!(chosen.to_hex(), "#fdfdfd");
2313	}
2314
2315	// ---- meta ----
2316
2317	#[test]
2318	fn parse_meta_with_name_and_variant() {
2319	let table: toml::Table = "[meta]\nname = \"Nord\"\nvariant = \"light\"\n"
2320	.parse()
2321	.unwrap();
2322	let meta = parse_meta("nord", &table, false);
2323	assert_eq!(meta.id, "nord");
2324	assert_eq!(meta.name, "Nord");
2325	assert_eq!(meta.variant, "light");
2326	assert!(!meta.is_custom);
2327	}
2328
2329	#[test]
2330	fn parse_meta_defaults_to_id_and_dark() {
2331	let table: toml::Table = "".parse().unwrap();
2332	let meta = parse_meta("fallback", &table, true);
2333	assert_eq!(meta.name, "fallback");
2334	assert_eq!(meta.variant, "dark");
2335	assert!(meta.is_custom);
2336	}
2337
2338	// ---- color math (formulas must match the apps they came from) ----
2339
2340	#[test]
2341	fn rgb_hex_roundtrip() {
2342	assert_eq!(
2343	Rgb::from_hex("#6196FF").unwrap(),
2344	Rgb {
2345	r: 0x61,
2346	g: 0x96,
2347	b: 0xff
2348	}
2349	);
2350	assert_eq!(
2351	Rgb::from_hex("#abc").unwrap(),
2352	Rgb {
2353	r: 0xaa,
2354	g: 0xbb,
2355	b: 0xcc
2356	}
2357	);
2358	assert_eq!(
2359	Rgb {
2360	r: 0x61,
2361	g: 0x96,
2362	b: 0xff
2363	}
2364	.to_hex(),
2365	"#6196ff"
2366	);
2367	assert!(Rgb::from_hex("not-a-color").is_none());
2368	}
2369
2370	#[test]
2371	fn oklab_roundtrips_within_tolerance() {
2372	for hex in ["#6196ff", "#2e3440", "#ffffff", "#000000", "#c0392b"] {
2373	let c = Rgb::from_hex(hex).unwrap();
2374	let back = Rgb::from_oklab(c.to_oklab());
2375	// Gamut round-trip is near-exact (±1 per channel from rounding).
2376	assert!((c.r as i16 - back.r as i16).abs() <= 1, "{hex} r");
2377	assert!((c.g as i16 - back.g as i16).abs() <= 1, "{hex} g");
2378	assert!((c.b as i16 - back.b as i16).abs() <= 1, "{hex} b");
2379	}
2380	}
2381
2382	#[test]
2383	fn wcag_contrast_known_pairs() {
2384	let white = Rgb {
2385	r: 255,
2386	g: 255,
2387	b: 255,
2388	};
2389	let black = Rgb { r: 0, g: 0, b: 0 };
2390	assert!((wcag_contrast(white, black) - 21.0).abs() < 0.01);
2391	assert!((wcag_contrast(white, white) - 1.0).abs() < 0.01);
2392	}
2393
2394	#[test]
2395	fn readable_on_picks_by_wcag() {
2396	assert_eq!(
2397	readable_on(Rgb {
2398	r: 255,
2399	g: 255,
2400	b: 255
2401	}),
2402	Rgb { r: 0, g: 0, b: 0 }
2403	);
2404	assert_eq!(
2405	readable_on(Rgb { r: 0, g: 0, b: 0 }),
2406	Rgb {
2407	r: 255,
2408	g: 255,
2409	b: 255
2410	}
2411	);
2412	// A light blue action -> black text reads better.
2413	let action = Rgb::from_hex("#6196ff").unwrap();
2414	assert_eq!(readable_on(action), Rgb { r: 0, g: 0, b: 0 });
2415	}
2416
2417	#[test]
2418	fn lighten_darken_move_oklab_lightness() {
2419	let c = Rgb::from_hex("#6196ff").unwrap();
2420	let l0 = c.to_oklab().l;
2421	assert!(lighten(c, 0.05).to_oklab().l > l0);
2422	assert!(darken(c, 0.05).to_oklab().l < l0);
2423	}
2424
2425	#[test]
2426	fn mix_endpoints_and_midpoint() {
2427	let a = Rgb::from_hex("#000000").unwrap();
2428	let b = Rgb::from_hex("#6196ff").unwrap();
2429	assert_eq!(mix(a, b, 0.0), a);
2430	assert_eq!(mix(a, b, 1.0), b);
2431	// Midpoint sits between the endpoints in OKLab lightness.
2432	let mid = mix(a, b, 0.5).to_oklab().l;
2433	assert!(mid > a.to_oklab().l && mid < b.to_oklab().l);
2434	}
2435
2436	// ---- extract + resolve ----
2437
2438	fn nord_toml() -> &'static str {
2439	r##"
2440	[meta]
2441	name = "Nord"
2442	variant = "dark"
2443
2444	[surface]
2445	page = "#2e3440"
2446	raised = "#3b4252"
2447	sunken = "#434c5e"
2448	overlay = "#3b4252"
2449
2450	[content]
2451	primary = "#d8dee9"
2452	secondary = "#e5e9f0"
2453	muted = "#616e88"
2454
2455	[action]
2456	primary = "#81a1c1"
2457
2458	[status]
2459	danger = "#bf616a"
2460	success = "#a3be8c"
2461	warning = "#ebcb8b"
2462	info = "#88c0d0"
2463
2464	[line]
2465	border = "#4c566a"
2466
2467	[category]
2468	one = "#bf616a"
2469	two = "#a3be8c"
2470	three = "#81a1c1"
2471	four = "#ebcb8b"
2472	five = "#b48ead"
2473	six = "#88c0d0"
2474	"##
2475	}
2476
2477	#[test]
2478	fn extract_colors_reads_intent_sections() {
2479	let table: toml::Table = nord_toml().parse().unwrap();
2480	let colors = extract_colors(&table);
2481	assert_eq!(colors.get("surface.page").unwrap(), "#2e3440");
2482	assert_eq!(colors.get("content.primary").unwrap(), "#d8dee9");
2483	assert_eq!(colors.get("action.primary").unwrap(), "#81a1c1");
2484	assert_eq!(colors.get("status.danger").unwrap(), "#bf616a");
2485	assert_eq!(colors.get("line.border").unwrap(), "#4c566a");
2486	assert_eq!(colors.get("category.five").unwrap(), "#b48ead");
2487	assert_eq!(colors.len(), 19);
2488	}
2489
2490	#[test]
2491	fn resolve_base_intents_passthrough() {
2492	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
2493	let t = resolve(&theme);
2494	assert_eq!(t.hex("surface-page"), Some("#2e3440"));
2495	assert_eq!(t.hex("content"), Some("#d8dee9")); // content.primary -> content
2496	// Not a passthrough: a tonal step of the ink, whatever the file said.
2497	assert_eq!(
2498	t.hex("content-muted").unwrap(),
2499	emphasized(
2500	Rgb::from_hex("#d8dee9").unwrap(),
2501	Rgb::from_hex("#2e3440").unwrap(),
2502	Emphasis::Muted
2503	)
2504	.to_hex()
2505	);
2506	assert_eq!(t.hex("action"), Some("#81a1c1"));
2507	assert_eq!(t.hex("danger"), Some("#bf616a"));
2508	assert_eq!(t.hex("border"), Some("#4c566a"));
2509	assert_eq!(t.hex("category-five"), Some("#b48ead"));
2510	}
2511
2512	#[test]
2513	fn a_tonal_step_lands_between_its_base_and_its_ground() {
2514	let ink = Rgb::from_hex("#d8dee9").unwrap();
2515	let page = Rgb::from_hex("#2e3440").unwrap();
2516	for step in [Emphasis::Full, Emphasis::Secondary, Emphasis::Muted] {
2517	let out = emphasized(ink, page, step).to_oklab().l;
2518	assert!(
2519	out <= ink.to_oklab().l && out >= page.to_oklab().l,
2520	"{step:?} left the interval between the ink and the page"
2521	);
2522	}
2523	assert_eq!(emphasized(ink, page, Emphasis::Full).to_hex(), ink.to_hex());
2524	}
2525
2526	#[test]
2527	fn tonal_steps_compose_rather_than_compound() {
2528	// Two steps toward one ground are one step toward it, which is what
2529	// makes deriving a family recursively well-defined. Within a rounding
2530	// step, since each hop lands back in 8-bit sRGB.
2531	let ink = Rgb::from_hex("#d8dee9").unwrap();
2532	let page = Rgb::from_hex("#2e3440").unwrap();
2533	let (a, b) = (0.12f32, 0.42f32);
2534	let twice = tonal(tonal(ink, page, a), page, b);
2535	let once = tonal(ink, page, a + b - a * b);
2536	let (x, y) = (twice.tuple(), once.tuple());
2537	for (l, r) in [(x.0, y.0), (x.1, y.1), (x.2, y.2)] {
2538	assert!(l.abs_diff(r) <= 1, "{twice:?} is not {once:?}");
2539	}
2540	}
2541
2542	#[test]
2543	fn a_ratio_outside_the_interval_is_clamped_rather_than_extrapolated() {
2544	let ink = Rgb::from_hex("#d8dee9").unwrap();
2545	let page = Rgb::from_hex("#2e3440").unwrap();
2546	assert_eq!(tonal(ink, page, -1.0).to_hex(), ink.to_hex());
2547	assert_eq!(tonal(ink, page, 2.0).to_hex(), page.to_hex());
2548	}
2549
2550	#[test]
2551	fn a_derived_token_key_is_the_family_plus_the_step() {
2552	assert_eq!(Emphasis::Muted.token("content"), "content-muted");
2553	assert_eq!(Emphasis::Secondary.token("content"), "content-secondary");
2554	assert_eq!(Emphasis::Full.token("content"), "content");
2555	// The point of the suffix being a property of the step: any family can
2556	// be grouped the same way without a second table saying what it means.
2557	assert_eq!(Emphasis::Muted.token("danger"), "danger-muted");
2558	}
2559
2560	#[test]
2561	fn every_shipped_theme_ramps_one_way() {
2562	// The property authoring the steps separately could not hold: three
2563	// themes had shipped a secondary lighter than their own primary, so a
2564	// renderer reading the emphasis order got the reverse of it.
2565	for (id, toml) in embedded_themes() {
2566	let theme = parse_theme_str(id, toml, false).unwrap();
2567	let t = resolve(&theme);
2568	let page = Rgb::from_hex(t.hex("surface-page").unwrap()).unwrap();
2569	let steps = ["content", "content-secondary", "content-muted"]
2570	.map(\|k\| wcag_contrast(Rgb::from_hex(t.hex(k).unwrap()).unwrap(), page));
2571	assert!(
2572	steps[0] > steps[1] && steps[1] > steps[2],
2573	"{id}: emphasis does not fall monotonically: {steps:?}"
2574	);
2575	}
2576	}
2577
2578	#[test]
2579	fn every_shipped_theme_takes_a_visible_first_step() {
2580	// The property that was missing when 2.6.0 derived these, and the
2581	// reason a pure-black ink shipped a secondary 3/255 away from it: the
2582	// ramp falling monotonically says nothing about how far it falls, and
2583	// a step nobody can see is not a step.
2584	for (id, toml) in embedded_themes() {
2585	let theme = parse_theme_str(id, toml, false).unwrap();
2586	let t = resolve(&theme);
2587	let ink = Rgb::from_hex(t.hex("content").unwrap()).unwrap();
2588	let secondary = Rgb::from_hex(t.hex("content-secondary").unwrap()).unwrap();
2589	let step = wcag_contrast(ink, secondary);
2590	assert!(
2591	step >= STEP_FLOOR,
2592	"{id}: secondary is {step:.2} from its ink, under the {STEP_FLOOR} floor"
2593	);
2594	}
2595	}
2596
2597	#[test]
2598	fn an_authored_emphasis_step_does_not_survive_loading() {
2599	// `nord_toml` still authors both, because a user's theme file might and
2600	// the answer has to be the same one.
2601	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
2602	assert_ne!(theme.colors.get("content.muted").unwrap(), "#616e88");
2603	assert_ne!(theme.colors.get("content.secondary").unwrap(), "#e5e9f0");
2604	}
2605
2606	#[test]
2607	fn a_theme_with_no_page_keeps_what_it_authored() {
2608	// Skip-missing: there is nothing to read the step against, so the step
2609	// is not taken and a half-written theme does not lose a colour.
2610	let mut colors = HashMap::new();
2611	colors.insert("content.primary".to_string(), "#d8dee9".to_string());
2612	colors.insert("content.muted".to_string(), "#616e88".to_string());
2613	derive_tonal_steps(&mut colors);
2614	assert_eq!(colors.get("content.muted").unwrap(), "#616e88");
2615	}
2616
2617	#[test]
2618	fn resolve_derived_intents() {
2619	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
2620	let t = resolve(&theme);
2621	let action = Rgb::from_hex("#81a1c1").unwrap();
2622	let page = Rgb::from_hex("#2e3440").unwrap();
2623	let _ = page;
2624	assert_eq!(
2625	t.hex("action-hover").unwrap(),
2626	lighten(action, 0.05).to_hex()
2627	);
2628	assert_eq!(
2629	t.hex("content-on-action").unwrap(),
2630	readable_on(action).to_hex()
2631	);
2632	assert_eq!(t.hex("focus-ring"), Some("#81a1c1"));
2633	assert_eq!(t.hex("hover-surface"), Some("#434c5e")); // = surface.sunken
2634	// Pruned by the usage audit (0 consumers): action-active, the *-surface
2635	// tints, selection, row-stripe. Apps that need them derive inline via
2636	// the shared mix().
2637	assert!(t.hex("action-active").is_none());
2638	assert!(t.hex("danger-surface").is_none());
2639	assert!(t.hex("selection").is_none());
2640	assert!(t.hex("row-stripe").is_none());
2641	}
2642
2643	#[test]
2644	fn resolve_bevel_intents() {
2645	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
2646	let t = resolve(&theme);
2647	let raised = Rgb::from_hex("#3b4252").unwrap();
2648	assert_eq!(
2649	t.hex("bevel-light").unwrap(),
2650	lighten(raised, 0.14).to_hex()
2651	);
2652	assert_eq!(t.hex("bevel-dark").unwrap(), darken(raised, 0.18).to_hex());
2653	}
2654
2655	// A bevel is two edges around one face, so both edges have to be visibly off
2656	// that face or the control never resolves as lit. The lightening clamps at
2657	// the top of the ramp, which means a theme authoring a white raised surface
2658	// gets a highlight identical to the surface it is meant to sit on.
2659	//
2660	// The list is asserted rather than merely reported so that changing a theme
2661	// has to come here and say so. Shrinking it is the fix; growing it is a
2662	// regression in the theme, not in this derivation.
2663	#[test]
2664	fn bevel_edges_are_distinct_from_their_face() {
2665	const CANNOT_BEVEL: &[&str] = &["neobrute", "oxocarbon-light"];
2666
2667	let mut degenerate: Vec<String> = Vec::new();
2668	for (id, source) in embedded_themes() {
2669	let theme = parse_theme_str(id, source, false).unwrap();
2670	let t = resolve(&theme);
2671	let Some(raised) = t.hex("surface-raised") else {
2672	continue;
2673	};
2674	let light = t.hex("bevel-light").expect("raised implies bevel-light");
2675	let dark = t.hex("bevel-dark").expect("raised implies bevel-dark");
2676	if light == raised \|\| dark == raised {
2677	degenerate.push(id.to_string());
2678	}
2679	}
2680	degenerate.sort();
2681
2682	assert_eq!(
2683	degenerate, CANNOT_BEVEL,
2684	"themes whose raised surface cannot hold both bevel edges"
2685	);
2686	}
2687
2688	// The well inverts by theme, so assert both directions explicitly rather
2689	// than only the one the light themes happen to take.
2690	#[test]
2691	fn resolve_well_intent_follows_the_content_direction() {
2692	// nord is dark: light text on a dark raised surface, so the well goes
2693	// down and away from the text.
2694	let dark = resolve(&parse_theme_str("nord", nord_toml(), false).unwrap());
2695	let dark_raised = Rgb::from_hex("#3b4252").unwrap();
2696	assert_eq!(
2697	dark.hex("surface-well").unwrap(),
2698	darken(dark_raised, 0.09).to_hex()
2699	);
2700
2701	// The shipped light themes take the other branch.
2702	let goingson = embedded_themes()
2703	.into_iter()
2704	.find(\|(id, _)\| *id == "goingson")
2705	.expect("goingson is embedded")
2706	.1;
2707	let light = resolve(&parse_theme_str("goingson", goingson, false).unwrap());
2708	let light_raised = light
2709	.hex("surface-raised")
2710	.and_then(Rgb::from_hex)
2711	.expect("goingson authors a raised surface");
2712	assert_eq!(
2713	light.hex("surface-well").unwrap(),
2714	lighten(light_raised, 0.07).to_hex()
2715	);
2716	}
2717
2718	// A well is a fill, not an edge, so the only thing that makes it read is
2719	// being a different color from the surface it is cut into.
2720	//
2721	// Same shape and the same asserted-list discipline as
2722	// `bevel_edges_are_distinct_from_their_face`, and it bites the same two
2723	// themes for the same reason: a raised surface already at the top of the
2724	// ramp has nothing lighter to go to.
2725	#[test]
2726	fn well_is_distinct_from_its_face() {
2727	const CANNOT_WELL: &[&str] = &["neobrute", "oxocarbon-light"];
2728
2729	let mut degenerate: Vec<String> = Vec::new();
2730	for (id, source) in embedded_themes() {
2731	let theme = parse_theme_str(id, source, false).unwrap();
2732	let t = resolve(&theme);
2733	let Some(raised) = t.hex("surface-raised") else {
2734	continue;
2735	};
2736	let well = t.hex("surface-well").expect("raised implies surface-well");
2737	if well == raised {
2738	degenerate.push(id.to_string());
2739	}
2740	}
2741	degenerate.sort();
2742
2743	assert_eq!(
2744	degenerate, CANNOT_WELL,
2745	"themes whose raised surface cannot hold a well"
2746	);
2747	}
2748
2749	// Distinct is not the same as visible. A face near the top of the ramp
2750	// clamps partway rather than exactly, which yields a well that differs from
2751	// its face by a hex digit and by nothing the eye can find. `rosepine-dawn`
2752	// authors raised at L=0.987 and gets 0.009 of the 0.07 it asked for.
2753	//
2754	// Worth a separate test from the one above because the fix differs: an
2755	// exactly-degenerate theme needs its raised surface off the ramp end, while
2756	// these need it merely lowered. Both fixes are the theme's, not this
2757	// derivation's, which is why the list is asserted rather than warned about.
2758	#[test]
2759	fn well_is_visible_against_its_face() {
2760	// Below this, the well and its face are the same surface to a reader.
2761	const MIN_DELTA_L: f32 = 0.02;
2762	const CANNOT_HOLD_A_VISIBLE_WELL: &[&str] =
2763	&["neobrute", "oxocarbon-light", "rosepine-dawn"];
2764
2765	let mut invisible: Vec<String> = Vec::new();
2766	for (id, source) in embedded_themes() {
2767	let theme = parse_theme_str(id, source, false).unwrap();
2768	let t = resolve(&theme);
2769	let (Some(raised), Some(well)) = (
2770	t.hex("surface-raised").and_then(Rgb::from_hex),
2771	t.hex("surface-well").and_then(Rgb::from_hex),
2772	) else {
2773	continue;
2774	};
2775	if (well.to_oklab().l - raised.to_oklab().l).abs() < MIN_DELTA_L {
2776	invisible.push(id.to_string());
2777	}
2778	}
2779	invisible.sort();
2780
2781	assert_eq!(
2782	invisible, CANNOT_HOLD_A_VISIBLE_WELL,
2783	"themes whose well is too close to its face to read as one"
2784	);
2785	}
2786
2787	// The three tests above each measure a derived color against the face it was
2788	// derived from, so a theme can pass all of them and still have nothing lift
2789	// off anything: the face itself sits on the page, and that relationship is
2790	// the one a bevel needs in order to read as an object rather than as a
2791	// rectangle with decorated edges. makenot.work passed all three and could
2792	// not hold a bevel, which is what this covers.
2793	//
2794	// The threshold is picked against the ramps already ruled on rather than
2795	// against a round number. makenot.work shipped at 0.024 and was invisible,
2796	// was tried at 0.036 and rejected as marginal on badges and chips, and was
2797	// accepted at 0.058; goingson and audiofiles sit at 0.119 and 0.065. Every
2798	// ramp judged inadequate is below 0.036 and every one judged adequate is
2799	// above 0.058, so the line goes in the gap between them. Note the unit: this
2800	// is oklab L on 0 to 1, not the CIE L* on 0 to 100 that the theme files quote
2801	// in their comments, and the two are not interchangeable.
2802	//
2803	// Most of the list is imported palettes, which were authored for syntax
2804	// highlighting and owe our depth model nothing. Failing here says a theme
2805	// cannot hold a bevel, not that it is wrong. Shrinking the list is the fix;
2806	// growing it is a regression in the theme, not in this derivation.
2807	//
2808	// tokyonight left the list on 2026-08-15, and it is the only entry that could
2809	// leave without a judgment call about someone else's palette. Its page and
2810	// raised were the identical hex, so it had no ramp at all rather than a
2811	// shallow one, and the fix is upstream's own `bg_highlight` (#292e42, 0.079
2812	// above the page) rather than a color we picked. The other nineteen are
2813	// shallow ramps in published palettes, which is a different claim, and they
2814	// stay deferred until every app is migrated and eyeballed.
2815	#[test]
2816	fn raised_is_distinct_from_page() {
2817	// Below this, a raised surface and the page under it are one surface to
2818	// a reader, whichever direction the theme ramps in.
2819	const MIN_DELTA_L: f32 = 0.05;
2820	const CANNOT_LIFT_OFF_THE_PAGE: &[&str] = &[
2821	"akari-dawn",
2822	"akari-night",
2823	"ayu-light",
2824	"ayu-mirage",
2825	"catppuccin-latte",
2826	"catppuccin-mocha",
2827	"dawnfox",
2828	"dracula",
2829	"everforest",
2830	"flatwhite",
2831	"gruvbox-light",
2832	"neobrute",
2833	"one-dark",
2834	"oxocarbon-dark",
2835	"oxocarbon-light",
2836	"poimandres",
2837	"rosepine",
2838	"rosepine-dawn",
2839	"solarized-dark",
2840	];
2841
2842	let mut flat: Vec<String> = Vec::new();
2843	for (id, source) in embedded_themes() {
2844	let theme = parse_theme_str(id, source, false).unwrap();
2845	let t = resolve(&theme);
2846	let (Some(page), Some(raised)) = (
2847	t.hex("surface-page").and_then(Rgb::from_hex),
2848	t.hex("surface-raised").and_then(Rgb::from_hex),
2849	) else {
2850	continue;
2851	};
2852	if (raised.to_oklab().l - page.to_oklab().l).abs() < MIN_DELTA_L {
2853	flat.push(id.to_string());
2854	}
2855	}
2856	flat.sort();
2857
2858	assert_eq!(
2859	flat, CANNOT_LIFT_OFF_THE_PAGE,
2860	"themes whose raised surface is too close to the page to lift off it"
2861	);
2862	}
2863
2864	// What the bevel pair does on a sixteen-color terminal, measured across the
2865	// shipped set rather than assumed. Two results, both load-bearing for a
2866	// consumer that has to render one there.
2867	//
2868	// Exactly one edge survives, never both. A raised face quantizes onto one of
2869	// the palette's three grays, and the palette is too coarse to hold anything
2870	// between that entry and its neighbour, so whichever edge is pushed toward
2871	// the end of the ramp the face already sits on lands back on the face. Light
2872	// themes and most dark ones keep the shadow and lose the highlight; a face
2873	// that quantizes to black keeps the highlight and loses the shadow.
2874	//
2875	// So a low-color consumer draws the single edge it can render, on the side
2876	// the palette left it, rather than a bevel that resolves on two sides.
2877	//
2878	// And `quantize_against` is the wrong function for this pair, though it is
2879	// the right one for a border. It answers "nearest entry that clears DISTINCT
2880	// against the background", which has no notion of direction, so both edges
2881	// are pushed onto the same contrasting entry and the bevel inverts on one
2882	// side. Plain `quantize` keeps them apart and in the right order.
2883	#[test]
2884	fn a_sixteen_color_terminal_gets_one_bevel_edge_and_not_two() {
2885	for (id, source) in embedded_themes() {
2886	let theme = parse_theme_str(id, source, false).unwrap();
2887	let t = resolve(&theme);
2888	let (Some(face), Some(light), Some(dark)) = (
2889	t.hex("surface-raised").and_then(Rgb::from_hex),
2890	t.hex("bevel-light").and_then(Rgb::from_hex),
2891	t.hex("bevel-dark").and_then(Rgb::from_hex),
2892	) else {
2893	continue;
2894	};
2895
2896	let face_index = quantize(face, &ANSI_16);
2897	let light_survives = quantize(light, &ANSI_16) != face_index;
2898	let dark_survives = quantize(dark, &ANSI_16) != face_index;
2899	assert!(
2900	light_survives != dark_survives,
2901	"{id}: expected exactly one bevel edge to survive 16 colors, \
2902	highlight {light_survives} shadow {dark_survives}"
2903	);
2904
2905	// Direction-blind, so it collapses the pair it is asked to separate.
2906	assert_eq!(
2907	quantize_against(light, face, &ANSI_16),
2908	quantize_against(dark, face, &ANSI_16),
2909	"{id}: quantize_against is expected to be unusable for a bevel pair"
2910	);
2911	}
2912	}
2913
2914	// 256 colors is where the bevel starts working. At 16 every shipped theme
2915	// loses an edge; here all but the five whose raised surface sits at the very
2916	// top of the ramp keep both, and those five fail for the reason they fail in
2917	// truecolor rather than for a palette reason.
2918	//
2919	// Three of them cannot bevel at any depth, so they are the
2920	// `bevel_edges_are_distinct_from_their_face` set. The other two are new here:
2921	// they hold a highlight in 24-bit, but not one wide enough to survive
2922	// rounding onto the cube.
2923	#[test]
2924	fn two_hundred_fifty_six_colors_keep_both_bevel_edges() {
2925	const LOSES_AN_EDGE: &[&str] = &[
2926	"gruvbox-light",
2927	"neobrute",
2928	"oxocarbon-light",
2929	"rosepine-dawn",
2930	];
2931
2932	let mut lost: Vec<String> = Vec::new();
2933	for (id, source) in embedded_themes() {
2934	let theme = parse_theme_str(id, source, false).unwrap();
2935	let t = resolve(&theme);
2936	let (Some(face), Some(light), Some(dark)) = (
2937	t.hex("surface-raised").and_then(Rgb::from_hex),
2938	t.hex("bevel-light").and_then(Rgb::from_hex),
2939	t.hex("bevel-dark").and_then(Rgb::from_hex),
2940	) else {
2941	continue;
2942	};
2943
2944	// Against the fixed region, which is what a consumer should use: a
2945	// match in the low sixteen is a match against a repaintable color.
2946	let f = quantize(face, ANSI_240);
2947	let l = quantize(light, ANSI_240);
2948	let d = quantize(dark, ANSI_240);
2949	if l == f \|\| d == f \|\| l == d {
2950	lost.push(id.to_string());
2951	}
2952	}
2953	lost.sort();
2954
2955	assert_eq!(
2956	lost, LOSES_AN_EDGE,
2957	"themes that cannot hold a two-tone bevel on a 256-color terminal"
2958	);
2959	}
2960
2961	#[test]
2962	fn the_256_table_has_its_three_regions() {
2963	// Index is the escape-sequence index, so the low sixteen must match.
2964	assert_eq!(ANSI_256[..16], ANSI_16);
2965	// The cube's corners, at both ends and one interior level.
2966	assert_eq!(ANSI_256[16].tuple(), (0, 0, 0));
2967	assert_eq!(ANSI_256[231].tuple(), (255, 255, 255));
2968	assert_eq!(ANSI_256[16 + 36 * 2 + 6 * 3 + 4].tuple(), (135, 175, 215));
2969	// The gray ramp runs 8 to 238 and contains neither black nor white.
2970	assert_eq!(ANSI_256[232].tuple(), (8, 8, 8));
2971	assert_eq!(ANSI_256[255].tuple(), (238, 238, 238));
2972	// The fixed region is the table minus the repaintable colors.
2973	assert_eq!(ANSI_240.len(), 240);
2974	assert_eq!(ANSI_240[0], ANSI_256[ANSI_240_OFFSET]);
2975	}
2976
2977	#[test]
2978	fn resolve_overlay_is_dark_translucent_scrim() {
2979	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
2980	let t = resolve(&theme);
2981	let overlay = t.hex("overlay").unwrap();
2982	assert!(
2983	overlay.starts_with("rgba("),
2984	"overlay is translucent: {overlay}"
2985	);
2986	assert!(overlay.ends_with(", 0.5)"));
2987	// The scrim tone is anchored very dark regardless of theme.
2988	let inner = overlay
2989	.trim_start_matches("rgba(")
2990	.trim_end_matches(", 0.5)");
2991	let parts: Vec<u8> = inner.split(", ").map(\|p\| p.parse().unwrap()).collect();
2992	let scrim = Rgb {
2993	r: parts[0],
2994	g: parts[1],
2995	b: parts[2],
2996	};
2997	assert!(scrim.to_oklab().l < 0.2, "scrim must be near-black");
2998	}
2999
3000	/// Every shipped theme derives it, on both polarities, and it is always a
3001	/// near-black translucent tone. A shadow tinted to a dark theme's own
3002	/// lightness would not read as one.
3003	#[test]
3004	fn elevation_is_a_near_black_cast_on_every_theme() {
3005	for (id, source) in embedded_themes() {
3006	let theme = parse_theme_str(id, source, false).unwrap();
3007	let t = resolve(&theme);
3008	let Some(elevation) = t.hex("elevation") else {
3009	panic!("{id} derives no elevation");
3010	};
3011	assert!(
3012	elevation.starts_with("rgba(") && elevation.ends_with(", 0.18)"),
3013	"{id}: elevation is translucent: {elevation}"
3014	);
3015	let inner = elevation
3016	.trim_start_matches("rgba(")
3017	.trim_end_matches(", 0.18)");
3018	let parts: Vec<u8> = inner.split(", ").map(\|p\| p.parse().unwrap()).collect();
3019	let cast = Rgb {
3020	r: parts[0],
3021	g: parts[1],
3022	b: parts[2],
3023	};
3024	assert!(
3025	cast.to_oklab().l < 0.2,
3026	"{id}: a cast shadow must be near-black, got {elevation}"
3027	);
3028	}
3029	}
3030
3031	/// The scrim and the cast share an anchor and differ only in weight. Stated
3032	/// as a test because the two are easy to drift apart, and a scrim that
3033	/// stopped matching the shadow under the thing it dims would show.
3034	#[test]
3035	fn elevation_and_the_scrim_are_the_same_tone() {
3036	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
3037	let t = resolve(&theme);
3038	let scrim = t.hex("overlay").unwrap();
3039	let cast = t.hex("elevation").unwrap();
3040	assert_eq!(
3041	scrim.trim_end_matches(", 0.5)"),
3042	cast.trim_end_matches(", 0.18)"),
3043	);
3044	}
3045
3046	/// The accessor that makes a translucent intent reachable from something
3047	/// that is not a stylesheet. Both spellings, and an opaque token answers
3048	/// 255 so a caller need not know which kind it asked for.
3049	#[test]
3050	fn rgba_reads_both_spellings() {
3051	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
3052	let t = resolve(&theme);
3053
3054	let (_, _, _, opaque) = t.rgba("surface-page").expect("page is a hex token");
3055	assert_eq!(opaque, 255);
3056
3057	let (r, g, b, alpha) = t.rgba("elevation").expect("elevation is translucent");
3058	assert_eq!(alpha, 46, "0.18 of 255");
3059	assert_eq!(t.rgb("elevation"), None, "rgb declines to drop the alpha");
3060
3061	let (sr, sg, sb, scrim) = t.rgba("overlay").expect("overlay is translucent");
3062	assert_eq!((sr, sg, sb), (r, g, b), "one tone, two weights");
3063	assert_eq!(scrim, 128);
3064	}
3065
3066	#[test]
3067	fn resolve_drops_non_hex_base_intent() {
3068	// A base intent that isn't a hex color must never reach the resolved
3069	// token set (it would otherwise be inlined verbatim into a <style>
3070	// block). Skipped like a missing intent; valid siblings survive.
3071	let theme = parse_theme_str(
3072	"x",
3073	"[surface]\npage = \"</style><script>alert(1)</script>\"\n[content]\nprimary = \"#111111\"\n",
3074	false,
3075	)
3076	.unwrap();
3077	let t = resolve(&theme);
3078	assert!(
3079	t.hex("surface-page").is_none(),
3080	"non-hex base intent leaked"
3081	);
3082	assert_eq!(t.hex("content").unwrap(), "#111111");
3083	// The injected markup appears in no resolved value.
3084	assert!(!t.intents.values().any(\|v\| v.contains('<')));
3085	}
3086
3087	#[test]
3088	fn resolve_skips_derived_when_source_missing() {
3089	// No [action] => no action-derived tokens.
3090	let theme = parse_theme_str(
3091	"x",
3092	"[surface]\npage = \"#000000\"\n[line]\nborder = \"#222222\"\n",
3093	false,
3094	)
3095	.unwrap();
3096	let t = resolve(&theme);
3097	assert!(t.hex("action").is_none());
3098	assert!(t.hex("action-hover").is_none());
3099	assert!(t.hex("selection").is_none());
3100	assert_eq!(
3101	t.hex("border-strong").unwrap(),
3102	darken(Rgb::from_hex("#222222").unwrap(), 0.05).to_hex()
3103	);
3104	}
3105
3106	#[test]
3107	fn rgb_accessor_for_native_consumers() {
3108	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
3109	let t = resolve(&theme);
3110	assert_eq!(t.rgb("action"), Some((0x81, 0xa1, 0xc1)));
3111	assert_eq!(t.rgb("nonexistent"), None);
3112	}
3113
3114	// ---- css emit ----
3115
3116	#[test]
3117	fn intent_css_vars_wraps_root_and_includes_tokens() {
3118	let theme = parse_theme_str("nord", nord_toml(), false).unwrap();
3119	let css = intent_css_vars(&resolve(&theme));
3120	assert!(css.starts_with(":root {\n"));
3121	assert!(css.contains(" --surface-page: #2e3440;\n"));
3122	assert!(css.contains(" --danger: #bf616a;\n"));
3123	assert!(css.contains(" --action-hover: "));
3124	assert!(css.trim_end().ends_with('}'));
3125	}
3126
3127	// ---- typography ----
3128
3129	#[test]
3130	fn the_font_tokens_are_two_names_and_each_ends_at_a_system_generic() {
3131	let css = typography_css_vars();
3132	assert!(css.starts_with(":root {\n"));
3133	assert!(css.contains(" --font-mono: \"Quasi Mono\", monospace;\n"));
3134	assert!(css.contains(" --font-sans: \"Quasi Body\", sans-serif;\n"));
3135
3136	// Layer 2 is one hop and no further. A third entry in either stack is
3137	// the shape the standard exists to delete: a chain nobody can predict
3138	// the metrics of, which is what `--font-sans: -apple-system,
3139	// BlinkMacSystemFont, 'Segoe UI', Roboto, ...` was in three apps.
3140	for stack in [FONT_MONO, FONT_SANS] {
3141	assert_eq!(stack.split(',').count(), 2, "{stack} is not one hop");
3142	}
3143
3144	// Two tokens, and no others. `--font-body`, `--font-heading` and
3145	// `--font-display` are gone or out of scope; a token appearing here
3146	// is a fifth answer to a question that has two.
3147	assert_eq!(css.matches("--font-").count(), 2);
3148	}
3149
3150	#[test]
3151	fn every_font_face_names_the_weight_range_because_the_mono_opens_at_200() {
3152	let css = font_face_css("/static/fonts");
3153
3154	assert_eq!(css.matches("@font-face").count(), 2);
3155	assert!(css.contains("src: url(\"/static/fonts/QuasiMono.woff2\") format(\"woff2\");"));
3156	assert!(css.contains("src: url(\"/static/fonts/QuasiBody.woff2\") format(\"woff2\");"));
3157
3158	// The trap. Atkinson Hyperlegible Mono's default instance is
3159	// ExtraLight and the cut keeps the axis, so a `@font-face` that omits
3160	// the range draws the whole UI at 200.
3161	assert_eq!(css.matches("font-weight: 200 800;").count(), 2);
3162
3163	// The families have to be exactly what the tokens ask for, or the
3164	// stack falls through to the generic and the face is dead weight.
3165	for family in [FONT_MONO, FONT_SANS] {
3166	let quoted = family.split(',').next().unwrap();
3167	assert!(css.contains(&format!("font-family: {quoted};")));
3168	}
3169	}
3170
3171	#[test]
3172	fn a_trailing_slash_on_the_base_url_does_not_double_it() {
3173	assert_eq!(font_face_css("fonts/"), font_face_css("fonts"));
3174	assert!(font_face_css("fonts").contains("url(\"fonts/QuasiMono.woff2\")"));
3175	}
3176
3177	// ---- typography, layer 0 ----
3178
3179	/// The live case: MNW's Young Serif, which reached the page through a
3180	/// hand-maintained `@font-face` and a `--font-heading` nothing else knew
3181	/// about.
3182	fn young_serif() -> FontOverride {
3183	FontOverride::new(FontSlot::Display, "\"Young Serif\", serif")
3184	.with_face(FontFace::new("Young Serif", ["ysrf.woff2", "ysrf.ttf"]))
3185	}
3186
3187	#[test]
3188	fn the_house_layer_alone_is_exactly_what_the_free_functions_emit() {
3189	let t = Typography::house("/static/fonts");
3190	assert_eq!(t.font_face_css(), font_face_css("/static/fonts"));
3191	assert_eq!(t.css_vars(), typography_css_vars());
3192	}
3193
3194	#[test]
3195	fn an_unoverridden_display_slot_defines_no_token_at_all() {
3196	// Not "defined empty": undefined, so the consumer's own fallback in
3197	// `var(--font-display, …)` renders. The MNW embeds depend on it.
3198	let t = Typography::house("fonts");
3199	assert!(!t.css_vars().contains("--font-display"));
3200	assert_eq!(t.resolve(FontSlot::Display), None);
3201	assert_eq!(t.css_vars().matches("--font-").count(), 2);
3202	}
3203
3204	#[test]
3205	fn an_override_adds_its_token_and_its_face_without_touching_the_house_two() {
3206	let t = Typography::house("/static/fonts").with_override(young_serif());
3207
3208	assert!(
3209	t.css_vars()
3210	.contains(" --font-display: \"Young Serif\", serif;\n")
3211	);
3212	assert!(
3213	t.css_vars()
3214	.contains(" --font-mono: \"Quasi Mono\", monospace;\n")
3215	);
3216	assert!(
3217	t.css_vars()
3218	.contains(" --font-sans: \"Quasi Body\", sans-serif;\n")
3219	);
3220	assert_eq!(t.resolve(FontSlot::Display), Some("\"Young Serif\", serif"));
3221
3222	let faces = t.font_face_css();
3223	assert_eq!(faces.matches("@font-face").count(), 3);
3224	assert!(faces.contains("font-family: \"Young Serif\";"));
3225	assert!(faces.contains("url(\"/static/fonts/ysrf.woff2\") format(\"woff2\")"));
3226	assert!(faces.contains("url(\"/static/fonts/ysrf.ttf\") format(\"truetype\")"));
3227
3228	// The house faces still come first, so a product face never shadows a
3229	// slot it did not claim.
3230	assert!(faces.find("Quasi Mono").unwrap() < faces.find("Young Serif").unwrap());
3231	}
3232
3233	#[test]
3234	fn overriding_mono_or_sans_replaces_the_house_stack_rather_than_adding_to_it() {
3235	// Nobody wants this today. A layer that only permits overriding the
3236	// slot nobody describes is the exemption restated, not a layer.
3237	let t = Typography::house("fonts").with_override(FontOverride::new(
3238	FontSlot::Mono,
3239	"\"Departure Mono\", monospace",
3240	));
3241
3242	assert!(
3243	t.css_vars()
3244	.contains(" --font-mono: \"Departure Mono\", monospace;\n")
3245	);
3246	assert!(!t.css_vars().contains("Quasi Mono"));
3247	assert_eq!(t.css_vars().matches("--font-").count(), 2);
3248	}
3249
3250	#[test]
3251	#[should_panic(expected = "--font-display is overridden twice")]
3252	fn a_second_override_of_one_slot_is_a_vocabulary_bug_and_says_so() {
3253	let _ = Typography::house("fonts")
3254	.with_override(young_serif())
3255	.with_override(FontOverride::new(FontSlot::Display, "\"Reglo\", serif"));
3256	}
3257
3258	#[test]
3259	fn an_absolute_source_is_taken_as_written_and_a_relative_one_joins_the_base() {
3260	let t = Typography::house("/static/fonts").with_override(
3261	FontOverride::new(FontSlot::Display, "\"Reglo\", serif").with_face(
3262	FontFace::new(
3263	"Reglo",
3264	["Reglo-Bold.woff2", "https://cdn.example/reglo.woff2"],
3265	)
3266	.with_weight("700"),
3267	),
3268	);
3269	let faces = t.font_face_css();
3270	assert!(faces.contains("url(\"/static/fonts/Reglo-Bold.woff2\")"));
3271	assert!(faces.contains("url(\"https://cdn.example/reglo.woff2\")"));
3272	assert!(faces.contains(" font-weight: 700;\n"));
3273	}
3274
3275	#[test]
3276	fn the_house_tier_renders_byte_for_byte_what_the_format_string_wrote() {
3277	// The house faces became `FontFace` values so they could be read as
3278	// well as emitted. Nothing about the sheet was meant to move, and this
3279	// is the whole of that claim: the literal the format string produced.
3280	let expected = concat!(
3281	"@font-face {\n",
3282	" font-family: \"Quasi Mono\";\n",
3283	" src: url(\"/static/fonts/QuasiMono.woff2\") format(\"woff2\");\n",
3284	" font-weight: 200 800;\n",
3285	" font-style: normal;\n",
3286	" font-display: swap;\n",
3287	"}\n\n",
3288	"@font-face {\n",
3289	" font-family: \"Quasi Body\";\n",
3290	" src: url(\"/static/fonts/QuasiBody.woff2\") format(\"woff2\");\n",
3291	" font-weight: 200 800;\n",
3292	" font-style: normal;\n",
3293	" font-display: swap;\n",
3294	"}\n\n",
3295	);
3296	assert_eq!(font_face_css("/static/fonts"), expected);
3297	}
3298
3299	#[test]
3300	fn a_house_slot_names_the_same_family_in_its_stack_and_in_its_face() {
3301	// The family is spelled once as a bare name and once inside a CSS
3302	// stack, because a stack cannot be built from a const at compile time.
3303	// A face whose family is not the one the stack names loads and is
3304	// never asked for.
3305	for (slot, family) in [
3306	(FontSlot::Mono, HOUSE_MONO_FAMILY),
3307	(FontSlot::Sans, HOUSE_SANS_FAMILY),
3308	] {
3309	let face = slot.house_face().expect("a house slot has a house face");
3310	assert_eq!(face.family(), family);
3311	assert!(
3312	slot.house_default()
3313	.unwrap()
3314	.starts_with(&format!("\"{family}\""))
3315	);
3316	}
3317	}
3318
3319	#[test]
3320	fn the_brand_tier_has_no_house_face_the_way_it_has_no_house_stack() {
3321	assert!(FontSlot::Display.house_face().is_none());
3322	assert!(FontSlot::Display.house_default().is_none());
3323	}
3324
3325	#[test]
3326	fn a_face_loading_renderer_reads_the_family_and_the_source_off_the_layer() {
3327	// The egui case, which has no stylesheet in the path at all: the
3328	// renderer registers the file under a name, and the name has to be
3329	// the one the stack spells or the two halves drift.
3330	let t = Typography::house("fonts").with_override(
3331	FontOverride::new(FontSlot::Display, "\"RecursiveMono\", monospace").with_face(
3332	FontFace::new("RecursiveMono", ["RecursiveMonoLnrSt-Bold.ttf"]).with_weight("700"),
3333	),
3334	);
3335
3336	let [face] = t.faces(FontSlot::Display) else {
3337	panic!("the display slot ships exactly one face");
3338	};
3339	assert_eq!(face.family(), "RecursiveMono");
3340	assert_eq!(face.sources(), ["RecursiveMonoLnrSt-Bold.ttf"]);
3341	assert!(
3342	t.resolve(FontSlot::Display)
3343	.unwrap()
3344	.contains(face.family())
3345	);
3346	}
3347
3348	#[test]
3349	fn a_weight_and_style_are_readable_now_that_the_builders_are_not_using_the_names() {
3350	let bold = FontFace::new("Reglo", ["Reglo-Bold.woff2"]).with_weight("700");
3351	assert_eq!(bold.weight(), Some("700"));
3352	assert_eq!(
3353	bold.style(),
3354	None,
3355	"unset means normal, not a stated normal"
3356	);
3357
3358	let italic = FontFace::new("Odd", ["odd.woff2"]).with_style("italic");
3359	assert_eq!(italic.weight(), None);
3360	assert_eq!(italic.style(), Some("italic"));
3361	}
3362
3363	#[test]
3364	fn the_house_faces_state_the_variable_range_a_direct_loader_has_to_name() {
3365	// The trap this closes: a variable face's own default instance is
3366	// whatever the base shipped, which for these is ExtraLight. A loader
3367	// that does not name a weight gets that and nothing says so.
3368	for slot in [FontSlot::Mono, FontSlot::Sans] {
3369	let face = slot.house_face().unwrap();
3370	assert_eq!(face.weight(), Some(HOUSE_WEIGHT_RANGE));
3371	assert_eq!(face.style(), Some("normal"));
3372	}
3373	}
3374
3375	#[test]
3376	fn a_source_is_read_back_unresolved_because_only_the_css_wants_a_url() {
3377	let t = Typography::house("/static/fonts").with_override(young_serif());
3378	assert_eq!(
3379	t.faces(FontSlot::Display)[0].sources(),
3380	["ysrf.woff2", "ysrf.ttf"]
3381	);
3382	// The same face, joined to the base, in the sheet.
3383	assert!(
3384	t.font_face_css()
3385	.contains("url(\"/static/fonts/ysrf.woff2\")")
3386	);
3387	}
3388
3389	#[test]
3390	fn a_slot_nobody_overrode_ships_no_faces_including_the_house_two() {
3391	let t = Typography::house("fonts").with_override(young_serif());
3392	assert!(t.faces(FontSlot::Mono).is_empty());
3393	assert!(t.faces(FontSlot::Sans).is_empty());
3394	assert_eq!(t.faces(FontSlot::Display).len(), 1);
3395	}
3396
3397	#[test]
3398	fn an_unrecognised_extension_gets_no_format_hint_rather_than_a_guessed_one() {
3399	let t = Typography::house("fonts").with_override(
3400	FontOverride::new(FontSlot::Display, "\"Odd\", serif")
3401	.with_face(FontFace::new("Odd", ["odd.eot"])),
3402	);
3403	assert!(t.font_face_css().contains("url(\"fonts/odd.eot\");"));
3404	assert!(!t.font_face_css().contains("format(\"eot\")"));
3405	}
3406
3407	#[test]
3408	fn css_puts_the_faces_before_the_tokens_that_name_them() {
3409	let t = Typography::house("fonts").with_override(young_serif());
3410	let css = t.css();
3411	assert!(css.starts_with("@font-face"));
3412	assert!(css.find("@font-face").unwrap() < css.find(":root").unwrap());
3413	}
3414
3415	// ---- loading / fs ----
3416
3417	#[test]
3418	fn load_and_resolve_round_trip() {
3419	let dir = tempfile::tempdir().unwrap();
3420	fs::write(dir.path().join("nord.toml"), nord_toml()).unwrap();
3421	let dirs = vec![(dir.path().to_path_buf(), false)];
3422	let t = load_semantic(&dirs, "nord").unwrap();
3423	assert_eq!(t.meta.name, "Nord");
3424	assert_eq!(t.hex("action"), Some("#81a1c1"));
3425	}
3426
3427	#[test]
3428	fn load_theme_rejects_invalid_id() {
3429	assert!(load_theme(&[], "../evil").is_err());
3430	}
3431
3432	fn meta(id: &str, variant: &str) -> ThemeMeta {
3433	ThemeMeta {
3434	id: id.to_string(),
3435	name: id.to_string(),
3436	variant: variant.to_string(),
3437	is_custom: false,
3438	}
3439	}
3440
3441	fn defaults() -> ThemeDefaults {
3442	ThemeDefaults::new("flatwhite", "nord")
3443	}
3444
3445	// The three the shipped themes actually declare.
3446	#[test]
3447	fn every_shipped_variant_parses() {
3448	assert_eq!(Variant::parse("light"), Some(Variant::Light));
3449	assert_eq!(Variant::parse("dark"), Some(Variant::Dark));
3450	assert_eq!(Variant::parse("high-contrast"), Some(Variant::HighContrast));
3451	assert_eq!(Variant::parse("sepia"), None);
3452	}
3453
3454	// parse_meta already defaults a missing variant to dark, so an
3455	// unrecognized one reading as light would have the crate disagreeing with
3456	// itself. alloy_tui did exactly that before this existed.
3457	#[test]
3458	fn an_unrecognized_variant_reads_the_way_a_missing_one_does() {
3459	assert_eq!(Variant::from("sepia"), Variant::Dark);
3460	assert_eq!(Variant::from(""), Variant::Dark);
3461
3462	let missing: toml::Table = "[meta]\nname = \"X\"\n".parse().unwrap();
3463	assert_eq!(parse_meta("x", &missing, false).kind(), Variant::Dark);
3464	}
3465
3466	#[test]
3467	fn a_selection_round_trips_through_any_store() {
3468	for (stored, expect) in [
3469	(Some("system"), ThemeSelection::Follow),
3470	(None, ThemeSelection::Follow),
3471	(Some(""), ThemeSelection::Follow),
3472	(Some(" "), ThemeSelection::Follow),
3473	(Some("nord"), ThemeSelection::Fixed("nord".into())),
3474	] {
3475	let parsed = ThemeSelection::parse(stored);
3476	assert_eq!(parsed, expect, "{stored:?}");
3477	assert_eq!(
3478	ThemeSelection::parse(Some(parsed.as_str())),
3479	expect,
3480	"what is written reads back as what was meant",
3481	);
3482	}
3483	}
3484
3485	// Nothing saved is follow-the-system, which is what Balanced Breakfast
3486	// expressed as an absent value and GoingsOn as a sentinel. Both are now the
3487	// same thing.
3488	#[test]
3489	fn nothing_chosen_yet_is_follow() {
3490	assert_eq!(ThemeSelection::default(), ThemeSelection::Follow);
3491	}
3492
3493	#[test]
3494	fn a_fixed_selection_wins_when_its_theme_is_installed() {
3495	let available = [meta("nord", "dark"), meta("flatwhite", "light")];
3496	let fixed = ThemeSelection::Fixed("nord".into());
3497	assert_eq!(
3498	fixed.resolve(Variant::Light, &defaults(), &available),
3499	"nord",
3500	"a chosen theme is not overridden by the ambient mode",
3501	);
3502	}
3503
3504	// Themes are deletable in three of the four apps. Handing back an id that
3505	// will fail to load only moves the error somewhere less helpful.
3506	#[test]
3507	fn a_fixed_selection_whose_theme_is_gone_falls_back() {
3508	let available = [meta("nord", "dark"), meta("flatwhite", "light")];
3509	let fixed = ThemeSelection::Fixed("deleted".into());
3510	assert_eq!(
3511	fixed.resolve(Variant::Light, &defaults(), &available),
3512	"flatwhite",
3513	);
3514	}
3515
3516	#[test]
3517	fn follow_picks_the_apps_default_for_the_ambient_mode() {
3518	let available = [meta("nord", "dark"), meta("flatwhite", "light")];
3519	let follow = ThemeSelection::Follow;
3520	assert_eq!(
3521	follow.resolve(Variant::Dark, &defaults(), &available),
3522	"nord",
3523	);
3524	assert_eq!(
3525	follow.resolve(Variant::Light, &defaults(), &available),
3526	"flatwhite",
3527	);
3528	}
3529
3530	// The behaviour Balanced Breakfast could not have: following the system
3531	// into a theme the user installed, when the app's own default is absent.
3532	#[test]
3533	fn follow_uses_any_installed_theme_of_the_right_variant() {
3534	let available = [meta("solarized-light", "light"), meta("mine", "dark")];
3535	assert_eq!(
3536	ThemeSelection::Follow.resolve(Variant::Dark, &defaults(), &available),
3537	"mine",
3538	"the app's `nord` is not installed, but a dark theme is",
3539	);
3540	}
3541
3542	// Always returns something: an app with no theme directory gets the id it
3543	// ships with, and the load error it would have had anyway.
3544	#[test]
3545	fn an_empty_catalog_still_names_the_apps_default() {
3546	assert_eq!(
3547	ThemeSelection::Follow.resolve(Variant::Dark, &defaults(), &[]),
3548	"nord",
3549	);
3550	}
3551
3552	#[test]
3553	fn high_contrast_falls_back_to_dark_unless_named() {
3554	let plain = defaults();
3555	assert_eq!(plain.for_variant(Variant::HighContrast), "nord");
3556
3557	let named = defaults().high_contrast("sharp");
3558	assert_eq!(named.for_variant(Variant::HighContrast), "sharp");
3559	}
3560
3561	// The bug this builder exists to prevent: the Alloy console pushed the
3562	// user's directory first under a comment reading "highest precedence
3563	// first", when both consumers of this vector resolve last-wins. A custom
3564	// theme lost to the packaged one of the same id.
3565	#[test]
3566	fn the_users_own_themes_outrank_everything() {
3567	let root = tempfile::tempdir().unwrap();
3568	let make = \|name: &str\| {
3569	let dir = root.path().join(name);
3570	std::fs::create_dir_all(&dir).unwrap();
3571	dir
3572	};
3573	let (bundled, system, custom) = (make("bundled"), make("system"), make("custom"));
3574
3575	let dirs = ThemeDirs::new()
3576	.custom(Some(custom.clone()))
3577	.bundled(Some(bundled.clone()))
3578	.system(Some(system.clone()))
3579	.build();
3580
3581	assert_eq!(
3582	dirs,
3583	vec![(bundled, false), (system, false), (custom.clone(), true)],
3584	"lowest precedence first, whatever order the tiers were added in",
3585	);
3586	assert!(dirs.last().unwrap().1, "only the user's tier is custom");
3587
3588	// And the ordering means what the consumers think it means.
3589	for dir in dirs.iter().map(\|(dir, _)\| dir) {
3590	std::fs::write(dir.join("shared.toml"), "[meta]\nname = \"x\"\n").unwrap();
3591	}
3592	assert_eq!(
3593	find_theme_path(&dirs, "shared").unwrap().0,
3594	custom.join("shared.toml"),
3595	"the user's copy is the one that loads",
3596	);
3597	}
3598
3599	#[test]
3600	fn a_directory_that_does_not_exist_is_dropped() {
3601	let root = tempfile::tempdir().unwrap();
3602	let real = root.path().join("real");
3603	std::fs::create_dir_all(&real).unwrap();
3604
3605	let dirs = ThemeDirs::new()
3606	.bundled(Some(root.path().join("nope")))
3607	.system(None)
3608	.custom(Some(real.clone()))
3609	.build();
3610
3611	assert_eq!(dirs, vec![(real, true)]);
3612	}
3613
3614	// A Tauri app has two bundled tiers: the resource dir in production and the
3615	// tree build.rs materialized for a dev run with no resource dir.
3616	#[test]
3617	fn more_than_one_bundled_tier_is_allowed() {
3618	let root = tempfile::tempdir().unwrap();
3619	let (first, second) = (root.path().join("a"), root.path().join("b"));
3620	std::fs::create_dir_all(&first).unwrap();
3621	std::fs::create_dir_all(&second).unwrap();
3622
3623	let dirs = ThemeDirs::new()
3624	.bundled(Some(first.clone()))
3625	.bundled(Some(second.clone()))
3626	.build();
3627	assert_eq!(dirs, vec![(first, false), (second, false)]);
3628	}
3629
3630	#[test]
3631	fn list_themes_from_dirs_finds_toml_files() {
3632	let dir = tempfile::tempdir().unwrap();
3633	fs::write(dir.path().join("t.toml"), "[meta]\nname = \"T\"\n").unwrap();
3634	fs::write(dir.path().join("x.txt"), "ignored").unwrap();
3635	let dirs = vec![(dir.path().to_path_buf(), false)];
3636	let themes = list_themes_from_dirs(&dirs);
3637	assert_eq!(themes.len(), 1);
3638	assert_eq!(themes[0].id, "t");
3639	}
3640
3641	#[test]
3642	fn find_theme_path_reverse_priority() {
3643	let d1 = tempfile::tempdir().unwrap();
3644	let d2 = tempfile::tempdir().unwrap();
3645	fs::write(d1.path().join("s.toml"), "[meta]\n").unwrap();
3646	fs::write(d2.path().join("s.toml"), "[meta]\n").unwrap();
3647	let dirs = vec![
3648	(d1.path().to_path_buf(), false),
3649	(d2.path().to_path_buf(), true),
3650	];
3651	let (path, is_custom) = find_theme_path(&dirs, "s").unwrap();
3652	assert!(is_custom);
3653	assert_eq!(path, d2.path().join("s.toml"));
3654	}
3655
3656	#[test]
3657	fn import_theme_valid_and_rejects_empty() {
3658	let src_dir = tempfile::tempdir().unwrap();
3659	let custom_dir = tempfile::tempdir().unwrap();
3660
3661	let good = src_dir.path().join("my-theme.toml");
3662	fs::write(&good, "[surface]\npage = \"#1a1b26\"\n").unwrap();
3663	let meta = import_theme(&good, custom_dir.path()).unwrap();
3664	assert_eq!(meta.id, "my-theme");
3665	assert!(custom_dir.path().join("my-theme.toml").exists());
3666
3667	let empty = src_dir.path().join("empty.toml");
3668	fs::write(&empty, "[meta]\nname = \"E\"\n").unwrap();
3669	assert!(import_theme(&empty, custom_dir.path()).is_err());
3670	}
3671
3672	#[test]
3673	fn import_theme_rejects_invalid_toml() {
3674	let src_dir = tempfile::tempdir().unwrap();
3675	let custom_dir = tempfile::tempdir().unwrap();
3676	let src = src_dir.path().join("bad.toml");
3677	fs::write(&src, "this is not [valid toml [[[").unwrap();
3678	assert!(import_theme(&src, custom_dir.path()).is_err());
3679	}
3680
3681	#[test]
3682	fn delete_theme_removes_and_guards() {
3683	let custom = tempfile::tempdir().unwrap();
3684	let path = custom.path().join("doomed.toml");
3685	fs::write(&path, "[surface]\npage = \"#000\"\n").unwrap();
3686	delete_theme(custom.path(), "doomed").unwrap();
3687	assert!(!path.exists());
3688	assert!(delete_theme(custom.path(), "../etc/passwd").is_err());
3689	assert!(delete_theme(custom.path(), "ghost").is_err());
3690	}
3691
3692	#[test]
3693	fn export_theme_copies_file() {
3694	let src_dir = tempfile::tempdir().unwrap();
3695	let dest_dir = tempfile::tempdir().unwrap();
3696	let content = "[meta]\nname = \"E\"\n[surface]\npage = \"#ffffff\"\n";
3697	fs::write(src_dir.path().join("e.toml"), content).unwrap();
3698	let dirs = vec![(src_dir.path().to_path_buf(), false)];
3699	let dest = dest_dir.path().join("out.toml");
3700	export_theme(&dirs, "e", &dest).unwrap();
3701	assert_eq!(fs::read_to_string(&dest).unwrap(), content);
3702	assert!(export_theme(&dirs, "missing", &dest).is_err());
3703	}
3704
3705	#[test]
3706	fn load_theme_preview_returns_role_swatches() {
3707	let dir = tempfile::tempdir().unwrap();
3708	fs::write(dir.path().join("nord.toml"), nord_toml()).unwrap();
3709	let dirs = vec![(dir.path().to_path_buf(), false)];
3710	let p = load_theme_preview(&dirs, "nord").unwrap();
3711	assert_eq!(p.background.as_deref(), Some("#2e3440")); // surface.page
3712	assert_eq!(p.foreground.as_deref(), Some("#d8dee9")); // content.primary
3713	assert_eq!(p.accent.as_deref(), Some("#81a1c1")); // action.primary
3714	assert_eq!(p.border.as_deref(), Some("#4c566a")); // line.border
3715	}
3716
3717	#[test]
3718	fn bundled_themes_dir_resolves_to_shipped_themes() {
3719	// The crate ships its themes, so this must resolve in-tree and the
3720	// Akari defaults the console falls back to must be present.
3721	let dir = bundled_themes_dir().expect("makeover ships a themes/ directory");
3722	assert!(dir.join("akari-dawn.toml").is_file());
3723	assert!(dir.join("akari-night.toml").is_file());
3724	}
3725
3726	#[test]
3727	fn every_theme_is_accounted_for_in_third_party_notices() {
3728	// Attribution is a redistribution obligation, not a nicety: adding a
3729	// theme without a notice entry silently ships someone's work
3730	// uncredited. Fail here instead.
3731	let notices = std::fs::read_to_string(
3732	Path::new(env!("CARGO_MANIFEST_DIR")).join("THIRD-PARTY-NOTICES.md"),
3733	)
3734	.expect("THIRD-PARTY-NOTICES.md must exist");
3735	let missing: Vec<&str> = embedded_themes()
3736	.map(\|(id, _)\| id)
3737	.filter(\|id\| !notices.contains(*id))
3738	.collect();
3739	assert!(
3740	missing.is_empty(),
3741	"themes missing from THIRD-PARTY-NOTICES.md: {missing:?}"
3742	);
3743	}
3744
3745	#[test]
3746	fn adapted_themes_carry_inline_attribution() {
3747	// Each adapted file must name its upstream in-file, so the credit
3748	// survives someone copying a single .toml out of the crate.
3749	const ORIGINALS: [&str; 5] = [
3750	"makenotwork",
3751	"goingson",
3752	"audiofiles",
3753	"high-contrast",
3754	"neobrute",
3755	];
3756	for (id, source) in embedded_themes() {
3757	if ORIGINALS.contains(&id) {
3758	continue;
3759	}
3760	assert!(
3761	source.contains("adapted from"),
3762	"adapted theme `{id}` is missing its inline attribution header"
3763	);
3764	}
3765	}
3766
3767	#[test]
3768	fn embedded_themes_match_the_directory() {
3769	// The embedded copy and themes/ are two views of one source. If they
3770	// ever disagree, path-based and path-free consumers render different
3771	// theme sets, which is exactly the drift shipping the data was meant
3772	// to prevent.
3773	let dir = bundled_themes_dir().unwrap();
3774	let mut on_disk: Vec<String> = std::fs::read_dir(&dir)
3775	.unwrap()
3776	.filter_map(\|e\| {
3777	let path = e.ok()?.path();
3778	if path.extension()? != "toml" {
3779	return None;
3780	}
3781	Some(path.file_stem()?.to_str()?.to_string())
3782	})
3783	.collect();
3784	let mut embedded: Vec<String> = embedded_themes().map(\|(id, _)\| id.to_string()).collect();
3785	on_disk.sort();
3786	embedded.sort();
3787	assert_eq!(embedded, on_disk, "embedded theme set drifted from themes/");
3788	}
3789
3790	#[test]
3791	fn every_embedded_theme_parses() {
3792	// Guards the path-free consumers (MNW server, the Tauri build steps)
3793	// the same way every_shipped_theme_loads guards the path-based ones.
3794	let mut count = 0;
3795	for (id, source) in embedded_themes() {
3796	parse_theme_str(id, source, false)
3797	.unwrap_or_else(\|e\| panic!("embedded theme `{id}` failed to parse: {e}"));
3798	count += 1;
3799	}
3800	assert!(count >= 30, "expected the full theme set, got {count}");
3801	}
3802
3803	#[test]
3804	fn every_shipped_theme_loads() {
3805	// Guards the data, not just the loader: a malformed or truncated
3806	// .toml in themes/ is a shipping bug, and it should fail here rather
3807	// than at a user's first launch.
3808	let dir = bundled_themes_dir().unwrap();
3809	let dirs = vec![(dir.clone(), false)];
3810	let themes = list_themes_from_dirs(&dirs);
3811	assert!(
3812	themes.len() >= 30,
3813	"expected the full theme set, got {}",
3814	themes.len()
3815	);
3816	for meta in &themes {
3817	load_theme(&dirs, &meta.id)
3818	.unwrap_or_else(\|e\| panic!("shipped theme `{}` failed to load: {e}", meta.id));
3819	}
3820	}
3821	}
3822