fix(projects/khora): adopt calendar-style header navigation

Arrange branding, today and date navigation around a dynamic period title, with refresh and view controls on the right.

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

projects/khora/khora/model.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import calendar
 import datetime as dt
 from dataclasses import dataclass
 
@@ -9,6 +10,31 @@ def week_dates(day: dt.date) -> tuple[dt.date, ...]:
     return tuple(monday + dt.timedelta(days=offset) for offset in range(7))
 
 
+def period_label(day: dt.date, mode: str) -> str:
+    if mode == "month":
+        return f"{day:%B} {day.year}"
+    if mode != "week":
+        return f"{day:%A, %B} {day.day}, {day.year}"
+
+    start, *_, end = week_dates(day)
+    if start.year != end.year:
+        return f"{start:%B} {start.day}, {start.year} – {end:%B} {end.day}, {end.year}"
+    if start.month != end.month:
+        return f"{start:%B} {start.day} – {end:%B} {end.day}, {start.year}"
+    return f"{start:%B} {start.day}–{end.day}, {start.year}"
+
+
+def shifted_date(day: dt.date, mode: str, direction: int) -> dt.date:
+    if mode != "month":
+        step = 7 if mode == "week" else 1
+        return day + dt.timedelta(days=step * direction)
+
+    month_index = day.year * 12 + day.month - 1 + direction
+    year, zero_based_month = divmod(month_index, 12)
+    month = zero_based_month + 1
+    return dt.date(year, month, min(day.day, calendar.monthrange(year, month)[1]))
+
+
 def event_slot_range(event: Event, day: dt.date) -> tuple[int, int]:
     """Return the half-hour rows occupied by a timed event on one day."""
     assert isinstance(event.start, dt.datetime)

projects/khora/khora/window.py

@@ -10,7 +10,7 @@ from gi.repository import Adw, Gio, GLib, Gtk, Pango
 
 from .colors import display_color
 from .khal_adapter import KhalRepository
-from .model import Event, event_slot_range, week_dates
+from .model import Event, event_slot_range, period_label, shifted_date, week_dates
 
 
 class KhoraWindow(Adw.ApplicationWindow):
@@ -53,16 +53,53 @@ class KhoraWindow(Adw.ApplicationWindow):
 
     def _build_header(self) -> Adw.HeaderBar:
         header = Adw.HeaderBar()
+        header.set_title_widget(Gtk.Box())
+
+        brand = Gtk.Box(spacing=8, margin_end=12)
+        brand.append(Gtk.Image(icon_name="x-office-calendar-symbolic", pixel_size=24))
+        brand.append(Gtk.Label(label="Khora", css_classes=["title"]))
+        header.pack_start(brand)
         header.pack_start(Gtk.Button(label="Today", action_name="win.today"))
 
+        navigation = Gtk.Box()
+        previous = Gtk.Button(
+            icon_name="go-previous-symbolic",
+            action_name="win.previous",
+            css_classes=["flat"],
+            tooltip_text="Previous period",
+        )
+        following = Gtk.Button(
+            icon_name="go-next-symbolic",
+            action_name="win.next",
+            css_classes=["flat"],
+            tooltip_text="Next period",
+        )
+        navigation.append(previous)
+        navigation.append(following)
+        header.pack_start(navigation)
+
+        self._period_label = Gtk.Label(css_classes=["title"], margin_start=6)
+        header.pack_start(self._period_label)
+
         menu = Gio.Menu()
         for mode in ("day", "week", "month", "agenda"):
             menu.append(mode.title(), f"win.view::{mode}")
         self._view_button = Gtk.MenuButton(label="Week", menu_model=menu)
-        header.set_title_widget(self._view_button)
-        header.pack_end(Gtk.Button(icon_name="view-refresh-symbolic", action_name="win.refresh"))
+
+        controls = Gtk.Box(spacing=6)
+        controls.append(
+            Gtk.Button(
+                icon_name="view-refresh-symbolic",
+                action_name="win.refresh",
+                tooltip_text="Refresh calendars",
+            )
+        )
+        controls.append(self._view_button)
+        header.pack_end(controls)
 
         self._install_action("today", self._on_today)
+        self._install_action("previous", lambda *_: self._navigate(-1))
+        self._install_action("next", lambda *_: self._navigate(1))
         self._install_action("refresh", lambda *_: self._refresh())
         view_action = Gio.SimpleAction.new("view", GLib.VariantType.new("s"))
         view_action.connect("activate", self._on_view_selected)
@@ -122,6 +159,7 @@ class KhoraWindow(Adw.ApplicationWindow):
         if self._repository is None or not hasattr(self, "_view_content"):
             return
 
+        self._period_label.set_label(period_label(self._selected_day(), self._view_mode))
         self._clear_view()
         self._empty.set_visible(False)
         if self._view_mode == "month":
@@ -292,6 +330,12 @@ class KhoraWindow(Adw.ApplicationWindow):
         self._calendar.select_day(GLib.DateTime.new_now_local())
         self._refresh()
 
+    def _navigate(self, direction: int) -> None:
+        target = shifted_date(self._selected_day(), self._view_mode, direction)
+        selected = GLib.DateTime.new_local(target.year, target.month, target.day, 0, 0, 0)
+        self._calendar.select_day(selected)
+        self._refresh()
+
     def _on_view_selected(self, _action: Gio.SimpleAction, parameter: GLib.Variant) -> None:
         self._view_mode = parameter.get_string()
         self._view_button.set_label(self._view_mode.title())

projects/khora/tests/test_model.py

@@ -1,6 +1,6 @@
 import datetime as dt
 
-from khora.model import Event, event_slot_range, week_dates
+from khora.model import Event, event_slot_range, period_label, shifted_date, week_dates
 
 
 def test_timed_event_label_uses_24_hour_time() -> None:
@@ -26,6 +26,27 @@ def test_week_dates_runs_from_monday_through_sunday() -> None:
     )
 
 
+def test_period_labels_follow_the_active_view() -> None:
+    day = dt.date(2026, 8, 15)
+
+    assert period_label(day, "day") == "Saturday, August 15, 2026"
+    assert period_label(day, "week") == "August 10–16, 2026"
+    assert period_label(day, "month") == "August 2026"
+    assert period_label(day, "agenda") == "Saturday, August 15, 2026"
+
+
+def test_week_label_handles_month_boundaries() -> None:
+    assert period_label(dt.date(2026, 9, 1), "week") == "August 31 – September 6, 2026"
+
+
+def test_shifted_date_uses_the_active_view_interval() -> None:
+    day = dt.date(2026, 8, 15)
+
+    assert shifted_date(day, "day", 1) == dt.date(2026, 8, 16)
+    assert shifted_date(day, "week", -1) == dt.date(2026, 8, 8)
+    assert shifted_date(dt.date(2026, 1, 31), "month", 1) == dt.date(2026, 2, 28)
+
+
 def test_event_slot_range_rounds_to_half_hours() -> None:
     event = Event(
         summary="Oddly timed meeting",