Fix median duration for even run counts

agentrace/cli.py

@@ -1,9 +1,9 @@
 """agentrace CLI.
 
-    agentrace list                 what did my subagents do
-    agentrace check               flag the suspicious results
-    agentrace show <id>           read one run in full
-    agentrace stats               where the time went
+agentrace list                 what did my subagents do
+agentrace check               flag the suspicious results
+agentrace show <id>           read one run in full
+agentrace stats               where the time went
 """
 
 from __future__ import annotations
@@ -12,6 +12,7 @@
 import json
 import sys
 from pathlib import Path
+from statistics import median
 
 from rich.console import Console
 from rich.markup import escape
@@ -80,7 +81,9 @@ def cmd_check(args) -> int:
             continue
         flagged += 1
         total_findings += len(findings)
-        console.print(f"\n[bold]{r.description or '(no description)'}[/] [dim]{r.tool_use_id[-8:]}[/]")
+        console.print(
+            f"\n[bold]{r.description or '(no description)'}[/] [dim]{r.tool_use_id[-8:]}[/]"
+        )
         for f in findings:
             colour = _SEV_COLOUR.get(f.severity, "white")
             console.print(f"  [{colour}]{f.severity:<6}[/] [bold]{f.check}[/]  {f.message}")
@@ -136,9 +139,9 @@ def cmd_stats(args) -> int:
     table.add_row("errored", f"{errors:,}")
     table.add_row("empty results", f"{empty:,}")
     if durations:
-        table.add_row("total agent time", f"{total_s/3600:.1f} h")
-        table.add_row("median run", f"{sorted(durations)[len(durations)//2]:.0f} s")
-        table.add_row("slowest run", f"{max(durations)/60:.1f} min")
+        table.add_row("total agent time", f"{total_s / 3600:.1f} h")
+        table.add_row("median run", f"{median(durations):.0f} s")
+        table.add_row("slowest run", f"{max(durations) / 60:.1f} min")
     table.add_row("prompt chars written", f"{prompt_chars:,}")
     table.add_row("result chars returned", f"{result_chars:,}")
     console.print(table)

tests/test_cli.py

@@ -2,6 +2,13 @@
 
 import subprocess
 import sys
+from argparse import Namespace
+from datetime import UTC, datetime, timedelta
+
+import pytest
+
+from agentrace import cli
+from agentrace.parse import AgentRun
 
 
 def run_cli(*args: str) -> subprocess.CompletedProcess[str]:
@@ -13,6 +20,42 @@ def run_cli(*args: str) -> subprocess.CompletedProcess[str]:
     )
 
 
+@pytest.mark.parametrize(
+    "durations,expected",
+    [
+        ([10, 20], "15 s"),
+        ([30, 10, 20], "20 s"),
+        ([10], "10 s"),
+        ([10, None, 20], "15 s"),
+        ([None], None),
+    ],
+)
+def test_stats_median(durations, expected, monkeypatch, capsys):
+    start = datetime(2026, 1, 1, tzinfo=UTC)
+    runs = [
+        AgentRun(
+            tool_use_id=str(i),
+            description="test",
+            prompt="prompt",
+            result="result",
+            started_at=start,
+            ended_at=start + timedelta(seconds=duration) if duration is not None else None,
+        )
+        for i, duration in enumerate(durations)
+    ]
+    monkeypatch.setattr(cli, "_load", lambda args: runs)
+
+    assert cli.cmd_stats(Namespace(json=False)) == 0
+
+    rows = capsys.readouterr().out.splitlines()
+    median_rows = [row for row in rows if "median run" in row]
+    if expected is None:
+        assert median_rows == []
+    else:
+        assert len(median_rows) == 1
+        assert " ".join(median_rows[0].split()) == f"median run {expected}"
+
+
 def test_file_and_dir_are_mutually_exclusive(tmp_path):
     transcript = tmp_path / "session.jsonl"
     transcript.write_text("")