feat: add execution counter column to task stack display

Tracks how many times each task has been moved to the top of the stack
via a new `execution_count` field on Task, incremented in `mark_current()`.
Displays the count as ×N in a new column before "started at", persisted
to YAML and backward-compatible (defaults to 0 for existing tasks).

https://claude.ai/code/session_01WfpSrDsJqKjvjCoS8uMkAF

Author: claude

python/src/task_stack/stack.py

@@ -22,6 +22,7 @@ class Task:
     duration: float = field(default=0.0)
     deleted_at: datetime | None = field(default=None)
     description: str = field(default="")
+    execution_count: int = field(default=0)
 
     @property
     def is_deleted(self) -> bool:
@@ -34,6 +35,7 @@ def mark_current(self, now: datetime | None = None) -> None:
         if self.started_at is None:
             self.started_at = now
         self.last_current = now
+        self.execution_count += 1
 
     def end_current_stint(self, now: datetime | None = None) -> None:
         """Accumulate the live stint into ``duration``.
@@ -79,6 +81,8 @@ def to_dict(self) -> dict:
             d["deleted_at"] = self.deleted_at.isoformat()
         if self.description:
             d["description"] = self.description
+        if self.execution_count:
+            d["execution_count"] = self.execution_count
         return d
 
     @staticmethod
@@ -100,6 +104,7 @@ def _parse(v: object) -> datetime | None:
             duration=duration,
             deleted_at=_parse(d.get("deleted_at")),
             description=d.get("description") or "",
+            execution_count=int(d.get("execution_count") or 0),
         )
 
 

python/src/task_stack/window.py

@@ -353,6 +353,7 @@ def _update_fonts(self) -> None:
         self._ts_col_w = f.measure("00m ago") + 8
         self._lc_col_w = f.measure("00m ago") + 8
         self._idx_col_w = f.measure("999") + 4
+        self._exec_col_w = f.measure("×99") + 4
 
     def _truncate(self, text: str, max_px: int, is_current: bool) -> str:
         font = self._font_obj_current if is_current else self._font_obj_normal
@@ -628,7 +629,8 @@ def _redraw(self) -> None:
         dur_x = width - right_pad
         lc_x = dur_x - self._dur_col_w - gap
         ts_x = lc_x - self._lc_col_w - gap
-        text_right = ts_x - self._ts_col_w - gap
+        exec_x = ts_x - self._ts_col_w - gap
+        text_right = exec_x - self._exec_col_w - gap
 
         if self._filter_text:
             self._visible_indices = [
@@ -685,6 +687,15 @@ def _redraw(self) -> None:
                 ts_text = st.format_timestamp(task.started_at, now)
                 dur_seconds = task.duration
                 col_fill = t.fg_muted
+            exec_text = f"×{task.execution_count}" if task.execution_count else "—"
+            c.create_text(
+                exec_x,
+                y0 + _ROW_HEIGHT // 2,
+                text=exec_text,
+                anchor=tk.E,
+                font=self._font_normal,
+                fill=col_fill,
+            )
             c.create_text(
                 ts_x,
                 y0 + _ROW_HEIGHT // 2,