feat: show scheduled prompts in session rows

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_tui.py

@@ -1032,6 +1032,51 @@ def test_format_session_text_status_colors():
     )  # Overlay0
 
 
+def _make_scheduled_prompt(due_at):
+    prompt = MagicMock()
+    prompt.due_at = due_at
+    prompt.status = "pending"
+    return prompt
+
+
+def test_format_session_text_shows_scheduled_prompt_countdown():
+    from datetime import datetime, timedelta
+    from hqt.tui.widgets.session_list import format_session_text
+
+    now = datetime(2026, 6, 11, 14, 0, 0)
+    scheduled = _make_scheduled_prompt(now + timedelta(minutes=12, seconds=1))
+
+    text = format_session_text(
+        "mywork",
+        "claude",
+        "idle",
+        "●",
+        scheduled_prompt=scheduled,
+        now=now,
+    )
+
+    assert "@ 13m" in text
+
+
+def test_format_session_text_shows_scheduled_prompt_clock_time():
+    from datetime import datetime, timedelta
+    from hqt.tui.widgets.session_list import format_session_text
+
+    now = datetime(2026, 6, 11, 14, 0, 0)
+    scheduled = _make_scheduled_prompt(now + timedelta(hours=2, minutes=30))
+
+    text = format_session_text(
+        "mywork",
+        "claude",
+        "idle",
+        "●",
+        scheduled_prompt=scheduled,
+        now=now,
+    )
+
+    assert "@ 16:30" in text
+
+
 @pytest.mark.asyncio
 async def test_session_list_renders_harness_name_brackets():
     """Regression: '[claude]' must be visible, not swallowed as a markup tag."""