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