feat(palette): sixteen ANSI colour ladders, cycled with c

beefy_player/palettes.py

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+"""The colour palettes everything in the UI draws from.
+
+Every colour in Beefy Player is a stock ANSI palette *name*, never RGB, so the
+TUI adopts whatever colours the terminal is configured with.  A palette here is
+therefore a short ladder of those names — the "gradient" is a quantised walk
+from the quiet end to the hot end, not an interpolation.
+
+The active palette drives the spectrum analyser, the album-art mosaic, the
+provider wordmarks and the pane corners; `c` cycles through them and the
+choice is remembered in the config file.
+"""
+
+from __future__ import annotations
+
+#: Dark → hot ladders of ANSI names.  Sixteen of them: seven hue gradients, a
+#: few near-monochromes, and the original spectrum.
+PALETTES: dict[str, tuple[str, ...]] = {
+    "spectrum": (
+        "cyan",
+        "blue",
+        "magenta",
+        "bright_magenta",
+        "yellow",
+        "bright_yellow",
+        "red",
+    ),
+    "rainbow": (
+        "red",
+        "bright_yellow",
+        "bright_green",
+        "bright_cyan",
+        "bright_blue",
+        "bright_magenta",
+    ),
+    "ocean": (
+        "bright_black",
+        "blue",
+        "bright_blue",
+        "cyan",
+        "bright_cyan",
+        "bright_white",
+    ),
+    "ember": (
+        "bright_black",
+        "red",
+        "bright_red",
+        "yellow",
+        "bright_yellow",
+        "bright_white",
+    ),
+    "mint": (
+        "bright_black",
+        "green",
+        "bright_green",
+        "cyan",
+        "bright_cyan",
+        "bright_white",
+    ),
+    "sunset": ("magenta", "bright_magenta", "red", "bright_red", "yellow"),
+    "violet": ("blue", "bright_blue", "magenta", "bright_magenta", "bright_white"),
+    "acid": ("bright_black", "green", "bright_green", "yellow", "bright_yellow"),
+    "neon": (
+        "bright_magenta",
+        "bright_red",
+        "bright_yellow",
+        "bright_green",
+        "bright_cyan",
+    ),
+    "sand": ("bright_black", "yellow", "bright_yellow", "white", "bright_white"),
+    "blood": ("bright_black", "red", "bright_red", "bright_magenta"),
+    "forest": ("bright_black", "green", "bright_green", "yellow", "bright_white"),
+    "ice": ("bright_white", "bright_cyan", "cyan", "bright_blue", "blue"),
+    "steel": ("bright_black", "white", "bright_white", "bright_cyan"),
+    "candy": ("magenta", "bright_magenta", "bright_cyan", "bright_yellow"),
+    "mono": ("bright_black", "white", "bright_white"),
+}
+
+#: Cycle order for the palette key.
+PALETTE_ORDER: tuple[str, ...] = tuple(PALETTES)
+
+#: What you get until you press `c`.
+DEFAULT_PALETTE = "spectrum"
+
+
+def palette_stops(name: str | None) -> tuple[str, ...]:
+    """The ladder for ``name``, falling back to the default palette."""
+    key = (name or "").strip().lower()
+    return PALETTES.get(key, PALETTES[DEFAULT_PALETTE])