Preserve historical activity selection (#103)

src/fenris/activity_selection.py

@@ -13,12 +13,23 @@ class IntervalIdentity:
     end_ts: str
 
 
+@dataclass(frozen=True)
+class HistoryDayIdentity:
+    """Stable identity for one recorded local-day summary."""
+
+    local_date: str
+    timezone: str
+    utc_start: str
+    utc_end: str
+
+
 class ActivitySelection:
     """Keep activity navigation state separate from its Textual rendering."""
 
     def __init__(self) -> None:
         self.view = "live"
         self.browse_date: str | None = None
+        self.selected_history_day: HistoryDayIdentity | None = None
         self.selected_history_hour: str | None = None
         self.history_range_days = HISTORY_RANGE_DEFAULT
         self.measure = "written"
@@ -34,11 +45,23 @@ class ActivitySelection:
         if view == "live":
             self.follow_live()
 
-    def select_history_date(self, date: str | None) -> None:
-        """Keep the chosen historical local date across refresh."""
-        if date != self.browse_date:
+    def select_history_date(
+        self,
+        date: str | None,
+        identity: HistoryDayIdentity | None = None,
+    ) -> None:
+        """Keep requested date and evidence identity across refresh."""
+        if date != self.browse_date or (
+            identity is not None and identity != self.selected_history_day
+        ):
             self.selected_history_hour = None
+        if date != self.browse_date:
+            self.selected_history_day = None
         self.browse_date = date
+        if identity is not None:
+            self.selected_history_day = identity
+        elif date is None:
+            self.selected_history_day = None
 
     def select_history_hour(self, hour: str | None) -> None:
         """Keep the chosen historical hour across refresh."""
@@ -53,6 +76,7 @@ class ActivitySelection:
         """Resume following the newest interval and clear stale-pin notices."""
         self.view = "live"
         self.browse_date = None
+        self.selected_history_day = None
         self.selected_history_hour = None
         self.following_live = True
         self.selected_live_interval = None