feat(projects/khora): color-code calendar events

Render calendar colors beside both event and calendar rows, including
conversion of khal named and xterm palette values.

Assisted-by: pi (gpt-5.6-sol)

projects/khora/src/khora/colors.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+import re
+
+_DEFAULT = "#3584e4"
+_ANSI = (
+    "#241f31",
+    "#c01c28",
+    "#26a269",
+    "#a2734c",
+    "#1c71d8",
+    "#a347ba",
+    "#2aa1b3",
+    "#deddda",
+    "#5e5c64",
+    "#ed333b",
+    "#57e389",
+    "#f8e45c",
+    "#62a0ea",
+    "#c061cb",
+    "#5bc8d7",
+    "#ffffff",
+)
+_NAMED = dict(
+    zip(
+        (
+            "black",
+            "dark red",
+            "dark green",
+            "brown",
+            "dark blue",
+            "dark magenta",
+            "dark cyan",
+            "white",
+            "dark gray",
+            "light red",
+            "light green",
+            "yellow",
+            "light blue",
+            "light magenta",
+            "light cyan",
+            "light gray",
+        ),
+        _ANSI,
+        strict=True,
+    )
+)
+_HEX_COLOR = re.compile(r"#[0-9a-fA-F]{3}(?:[0-9a-fA-F]{3})?(?:[0-9a-fA-F]{2})?")
+
+
+def display_color(value: str | None) -> str:
+    """Turn khal's terminal-oriented color values into GTK-friendly hex."""
+    if not value or value == "auto":
+        return _DEFAULT
+    if _HEX_COLOR.fullmatch(value):
+        return value
+    if value in _NAMED:
+        return _NAMED[value]
+    if value.isdigit() and 0 <= (index := int(value)) <= 255:
+        return _xterm_color(index)
+    return _DEFAULT
+
+
+def _xterm_color(index: int) -> str:
+    if index < 16:
+        return _ANSI[index]
+    if index < 232:
+        index -= 16
+        levels = (0, 95, 135, 175, 215, 255)
+        red, remainder = divmod(index, 36)
+        green, blue = divmod(remainder, 6)
+        return f"#{levels[red]:02x}{levels[green]:02x}{levels[blue]:02x}"
+    gray = 8 + (index - 232) * 10
+    return f"#{gray:02x}{gray:02x}{gray:02x}"

projects/khora/src/khora/window.py

@@ -8,6 +8,7 @@ gi.require_version("Adw", "1")
 gi.require_version("Gtk", "4.0")
 from gi.repository import Adw, Gio, GLib, Gtk
 
+from .colors import display_color
 from .khal_adapter import KhalRepository
 from .model import Event
 
@@ -83,6 +84,7 @@ class KhoraWindow(Adw.ApplicationWindow):
             toggle = Gtk.Switch(active=True, valign=Gtk.Align.CENTER)
             toggle.connect("notify::active", self._on_calendar_toggled, calendar.name)
             row = Adw.ActionRow(title=calendar.name, activatable=True)
+            row.add_prefix(self._color_dot(calendar.color))
             row.add_suffix(toggle)
             row.set_activatable_widget(toggle)
             calendars.append(row)
@@ -136,7 +138,15 @@ class KhoraWindow(Adw.ApplicationWindow):
         details = f"{event.time_label} · {event.calendar}"
         if event.location:
             details += f" · {event.location}"
-        return Adw.ActionRow(title=event.summary, subtitle=details)
+        row = Adw.ActionRow(title=event.summary, subtitle=details)
+        row.add_prefix(KhoraWindow._color_dot(event.color))
+        return row
+
+    @staticmethod
+    def _color_dot(color: str | None) -> Gtk.Label:
+        dot = Gtk.Label(valign=Gtk.Align.CENTER)
+        dot.set_markup(f'<span foreground="{display_color(color)}" size="18000">●</span>')
+        return dot
 
     def _on_calendar_toggled(self, button: Gtk.Switch, _property, name: str) -> None:
         if button.get_active():

projects/khora/tests/test_colors.py

@@ -0,0 +1,18 @@
+from khora.colors import display_color
+
+
+def test_preserves_html_colors() -> None:
+    assert display_color("#c01c28") == "#c01c28"
+
+
+def test_converts_khal_named_colors() -> None:
+    assert display_color("light blue") == "#62a0ea"
+
+
+def test_converts_xterm_color_cube() -> None:
+    assert display_color("196") == "#ff0000"
+
+
+def test_unknown_colors_use_accent_fallback() -> None:
+    assert display_color("auto") == "#3584e4"
+    assert display_color("chartreuse, probably") == "#3584e4"