Use a show's real theme colors instead of guessing from its id

Replaces the id-based theme lookup (/api/state's theme.active mapped to
this app's own hardcoded COLOR_SCHEMES) with the real, currently-in-effect
token values from /api/themes. SUB/WAVE themes aren't a fixed set of 8
presets -- an operator can add their own theme JSON with arbitrary token
values (controller/src/themes.ts loads built-ins plus optional files from
${STATE_DIR}/themes/), so a theme id like "cyberpunk" on some station
was never guaranteed to match this app's own guess at its hex values.

Also fixes the precedence question directly: /api/themes exposes
activeSource ("show" or "station", per controller's own
theme-provenance.ts), so the override only applies when a show has
genuinely pinned its own theme -- when it's "station" (no show-level
pin), the user's own configured color_scheme is used, not the station's
default, which is what was actually wanted.

Token values aren't all plain hex, though: surveyed every token across
every theme on the live test station and found three formats in use --
"#rrggbb", "oklch(L C H)", and "color-mix(in oklab, COLOR1 P1%, COLOR2)"
(COLOR1/COLOR2 themselves hex or oklch, sometimes nested). Implements
the standard CSS Color 4 / Bjorn Ottosson OKLab conversion to handle all
three. Verified three ways before trusting it: hex -> OKLab -> hex
round-trips to the exact original hex; oklch(L C H) for pure red/green/
blue/white matches their well-known reference hex values exactly; and
the color-mix outputs were cross-checked against an independent Python
implementation of the same formulas and matched exactly.

Token-to-role mapping: background/text/accent/meta/separator/bar_empty
<- --bg/--ink/--accent/--muted/--line/--surface, confirmed present on
every theme on the live station. --line is usually a translucent rgba
in SUB/WAVE's own themes -- preserved as an 8-digit #rrggbbaa hex
(alpha carried through the OKLab math too) rather than flattened to
opaque, matching the alpha-hex format already used elsewhere in this
file (e.g. the corner ticks' "#00000080").

Verified end-to-end: a test render with the real "blueprint" theme's
tokens forced through activeSource="show" produced the exact expected
background pixel (10,58,146 = #0a3a92); the live station (currently no
show-level override, activeSource="station") correctly falls back to
an explicitly configured color_scheme=vinyl instead of being overridden.

subwave_nowplaying.star

@@ -13,6 +13,7 @@ load("time.star", "time")
 load("animation.star", "animation")
 load("filter.star", "filter")
 load("random.star", "random")
+load("math.star", "math")
 
 DEFAULT_STATION_URL = ""
 NOWPLAYING_TTL = 20
@@ -198,11 +199,14 @@ def main(config):
 
     # A show's own theme override (if any) wins over the user's configured
     # color_scheme, mirroring what SUB/WAVE's own web UI does -- see
-    # _fetch_show_theme. Falls back to the configured scheme on a fetch
-    # failure or an id this app doesn't recognize, rather than erroring.
-    show_theme_id = _fetch_show_theme(station_url)
-    if show_theme_id != None and show_theme_id in COLOR_SCHEMES:
-        colors = COLOR_SCHEMES[show_theme_id]
+    # _fetch_show_colors. Only when activeSource is genuinely "show" (a
+    # show with its own themeId pinned, outranking the station default) --
+    # when it's "station" (no show-level override), the user's own
+    # configured color_scheme is respected instead, not the station's
+    # default. Falls back to the configured scheme on any fetch failure.
+    show_colors = _fetch_show_colors(station_url)
+    if show_colors != None:
+        colors = show_colors
 
     art = _fetch_cover(station_url, now["subsonic_id"])
     progress = _track_progress(now["subsonic_id"], now["duration"])
@@ -987,27 +991,203 @@ def _format_time_temp(clock, weather):
 
     return " · ".join(parts)
 
-def _fetch_show_theme(station_url):
-    # SUB/WAVE lets a show override the station's default color theme
-    # (controller/src/routes/public.ts resolves this server-side already:
-    # activeShow?.themeId || station default). That resolved value rides
-    # on /api/state's theme.active, not /api/now-playing -- a separate
-    # fetch, not a field on the response this app already pulls.
-    #
-    # Theme ids there use hyphens (e.g. "classic-light"), this app's
-    # COLOR_SCHEMES keys use underscores ("classic_light") -- same 8
-    # names otherwise (confirmed against SUB/WAVE's own theme registry),
-    # so swapping the separator is enough to look it up directly rather
-    # than needing an explicit id-mapping table.
-    rep = http.get(station_url + "/api/state", ttl_seconds = NOWPLAYING_TTL)
+# SUB/WAVE themes are plain CSS custom properties, not just a fixed set of
+# 8 preset ids: an operator can add their own theme JSON with arbitrary
+# token values (controller/src/themes.ts loads built-ins from a bundled
+# dir *plus* optional files from ${STATE_DIR}/themes/), so a theme named
+# e.g. "cyberpunk" on one station isn't guaranteed to be *this app's*
+# hardcoded COLOR_SCHEMES["cyberpunk"] hex values. /api/themes exposes
+# the real, currently-in-effect token values directly, so _fetch_show_colors
+# below reads those instead of mapping a theme id to our own guess.
+#
+# Token values aren't all plain hex, though -- surveyed every token across
+# every theme on the live test station and found three formats in use:
+# "#rrggbb", "oklch(L C H)", and "color-mix(in oklab, COLOR1 P1%, COLOR2)"
+# (where COLOR1/COLOR2 can themselves be hex or oklch, nested). The oklch
+# <-> sRGB math below (and the inverse, hex -> OKLab, needed to mix a hex
+# color against an oklch one) is the standard CSS Color 4 / Bjorn Ottosson
+# OKLab conversion -- verified two ways before trusting it: round-tripping
+# hex -> OKLab -> hex returned the exact original hex for several colors,
+# and converting oklch(L C H) for pure red/green/blue/white against their
+# well-known reference hex values matched exactly. The color-mix outputs
+# were cross-checked against an independent Python implementation of the
+# same formulas and matched exactly too.
+PI = 3.14159265358979
+
+def _clamp01(x):
+    return max(0.0, min(1.0, x))
+
+def _hex2(n):
+    s = "%x" % n
+    return "0" + s if len(s) < 2 else s
+
+def _srgb_to_linear(c):
+    if c <= 0.04045:
+        return c / 12.92
+    return math.pow((c + 0.055) / 1.055, 2.4)
+
+def _linear_to_srgb(c):
+    c = _clamp01(c)
+    if c <= 0.0031308:
+        return c * 12.92
+    return 1.055 * math.pow(c, 1.0 / 2.4) - 0.055
+
+def _hex_to_rgb01(hex_str):
+    hex_str = hex_str.lstrip("#")
+    return (int(hex_str[0:2], 16) / 255.0, int(hex_str[2:4], 16) / 255.0, int(hex_str[4:6], 16) / 255.0)
+
+def _rgb01_to_hex(r, g, b):
+    ri = int(_clamp01(r) * 255 + 0.5)
+    gi = int(_clamp01(g) * 255 + 0.5)
+    bi = int(_clamp01(b) * 255 + 0.5)
+    return "#" + _hex2(ri) + _hex2(gi) + _hex2(bi)
+
+def _linear_rgb_to_oklab(r, g, b):
+    l = 0.4122214708 * r + 0.5363325363 * g + 0.0514459929 * b
+    m = 0.2119034982 * r + 0.6806995451 * g + 0.1073969566 * b
+    s = 0.0883024619 * r + 0.2817188376 * g + 0.6299787005 * b
+    l_ = math.pow(l, 1.0 / 3.0) if l >= 0 else -math.pow(-l, 1.0 / 3.0)
+    m_ = math.pow(m, 1.0 / 3.0) if m >= 0 else -math.pow(-m, 1.0 / 3.0)
+    s_ = math.pow(s, 1.0 / 3.0) if s >= 0 else -math.pow(-s, 1.0 / 3.0)
+    L = 0.2104542553 * l_ + 0.7936177850 * m_ - 0.0040720468 * s_
+    A = 1.9779984951 * l_ - 2.4285922050 * m_ + 0.4505937099 * s_
+    B = 0.0259040371 * l_ + 0.7827717662 * m_ - 0.8086757660 * s_
+    return (L, A, B)
+
+def _oklab_to_linear_rgb(L, A, B):
+    l_ = L + 0.3963377774 * A + 0.2158037573 * B
+    m_ = L - 0.1055613458 * A - 0.0638541728 * B
+    s_ = L - 0.0894841775 * A - 1.2914855480 * B
+    l = l_ * l_ * l_
+    m = m_ * m_ * m_
+    s = s_ * s_ * s_
+    r = 4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s
+    g = -1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s
+    bb = -0.0041960863 * l - 0.7034186147 * m + 1.7076147010 * s
+    return (r, g, bb)
+
+def _hex_to_oklab(hex_str):
+    r, g, b = _hex_to_rgb01(hex_str)
+    return _linear_rgb_to_oklab(_srgb_to_linear(r), _srgb_to_linear(g), _srgb_to_linear(b))
+
+def _oklab_to_hex(L, A, B):
+    r, g, b = _oklab_to_linear_rgb(L, A, B)
+    return _rgb01_to_hex(_linear_to_srgb(r), _linear_to_srgb(g), _linear_to_srgb(b))
+
+def _oklch_to_oklab(l, c, h_deg):
+    h_rad = h_deg * PI / 180.0
+    return (l, c * math.cos(h_rad), c * math.sin(h_rad))
+
+def _rgb255_to_oklab(r, g, b):
+    return _linear_rgb_to_oklab(_srgb_to_linear(r / 255.0), _srgb_to_linear(g / 255.0), _srgb_to_linear(b / 255.0))
+
+def _find_top_level_comma(s):
+    # First comma not nested inside parens -- splits color-mix's two
+    # "COLOR PERCENT%" segments. A nested oklch(...) has no commas
+    # (space-separated), but rgb(...)/rgba(...) does, so this has to
+    # track paren depth rather than just split(",").
+    depth = 0
+    for i in range(len(s)):
+        ch = s[i]
+        if ch == "(":
+            depth += 1
+        elif ch == ")":
+            depth -= 1
+        elif ch == "," and depth == 0:
+            return i
+    return -1
+
+def _parse_color_token(s):
+    # Returns (L, A, B, alpha) in OKLab + a 0-1 alpha (1.0 unless the
+    # token is rgba(...) with a 4th value, or mixes one in).
+    s = s.strip()
+    if s.startswith("#"):
+        L, A, B = _hex_to_oklab(s)
+        return (L, A, B, 1.0)
+    if s.startswith("oklch("):
+        inner = s[s.index("(") + 1:s.rindex(")")]
+        parts = [p for p in inner.split(" ") if p != ""]
+        L, A, B = _oklch_to_oklab(float(parts[0]), float(parts[1]), float(parts[2]))
+        return (L, A, B, 1.0)
+    if s.startswith("rgba(") or s.startswith("rgb("):
+        inner = s[s.index("(") + 1:s.rindex(")")]
+        parts = [p.strip() for p in inner.split(",")]
+        L, A, B = _rgb255_to_oklab(float(parts[0]), float(parts[1]), float(parts[2]))
+        alpha = float(parts[3]) if len(parts) > 3 else 1.0
+        return (L, A, B, alpha)
+    if s.startswith("color-mix("):
+        inner = s[s.index("(") + 1:s.rindex(")")]
+        after_space = inner[len("in oklab,"):].strip() if inner.startswith("in oklab,") else inner
+        split_at = _find_top_level_comma(after_space)
+        seg1 = after_space[:split_at].strip()
+        seg2 = after_space[split_at + 1:].strip()
+
+        def _split_color_pct(seg):
+            if seg.endswith("%"):
+                last_space = seg.rindex(" ")
+                return seg[:last_space].strip(), float(seg[last_space + 1:-1])
+            return seg, None
+
+        color1, pct1 = _split_color_pct(seg1)
+        color2, pct2 = _split_color_pct(seg2)
+        if pct1 == None and pct2 == None:
+            pct1 = 50.0
+        elif pct1 == None:
+            pct1 = 100.0 - pct2
+        L1, A1, B1, Alpha1 = _parse_color_token(color1)
+        L2, A2, B2, Alpha2 = _parse_color_token(color2)
+        t = pct1 / 100.0
+        return (
+            L1 * t + L2 * (1 - t),
+            A1 * t + A2 * (1 - t),
+            B1 * t + B2 * (1 - t),
+            Alpha1 * t + Alpha2 * (1 - t),
+        )
+    fail("unrecognized color token: " + s)
+
+def _token_to_hex(s):
+    # 8-digit #rrggbbaa when the token isn't fully opaque (e.g. --line is
+    # usually a translucent rgba in SUB/WAVE's own themes), matching the
+    # alpha-hex format already used elsewhere in this file (e.g. the
+    # corner ticks' "#00000080") rather than flattening semi-transparent
+    # tokens to an opaque color that wouldn't match the station's own site.
+    L, A, B, alpha = _parse_color_token(s)
+    hex6 = _oklab_to_hex(L, A, B)
+    if alpha >= 1.0:
+        return hex6
+    return hex6 + _hex2(int(_clamp01(alpha) * 255 + 0.5))
+
+def _fetch_show_colors(station_url):
+    rep = http.get(station_url + "/api/themes", ttl_seconds = NOWPLAYING_TTL)
     if rep.status_code != 200:
         return None
 
-    theme_id = (rep.json().get("theme", {}) or {}).get("active", "")
-    if not theme_id:
+    data = rep.json()
+    if data.get("activeSource", "") != "show":
         return None
 
-    return theme_id.replace("-", "_")
+    active_id = data.get("active", "")
+    theme = None
+    for t in data.get("themes", []):
+        if t.get("id", "") == active_id:
+            theme = t
+            break
+    if theme == None:
+        return None
+
+    tokens = theme.get("tokens", {}) or {}
+    required = ("--bg", "--ink", "--accent", "--muted", "--line", "--surface")
+    if not all([k in tokens for k in required]):
+        return None
+
+    return {
+        "background": _token_to_hex(tokens["--bg"]),
+        "text": _token_to_hex(tokens["--ink"]),
+        "accent": _token_to_hex(tokens["--accent"]),
+        "meta": _token_to_hex(tokens["--muted"]),
+        "separator": _token_to_hex(tokens["--line"]),
+        "bar_empty": _token_to_hex(tokens["--surface"]),
+    }
 
 def _fetch_cover(station_url, subsonic_id):
     if not subsonic_id: