fix: refuse ambiguous Codex session-id capture

When more than one rollout matches the project cwd within the capture
window, return None and warn instead of guessing the earliest. The worst
case is now a kept placeholder id, never a wrong one. Part of the P2
capture-race fix.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/hqt/harnesses/configurators/codex.py

@@ -1,9 +1,12 @@
 import json
+import logging
 from datetime import datetime
 from pathlib import Path
 
 from hqt.harnesses.base import HarnessConfigurator, SpawnConfig
 
+log = logging.getLogger(__name__)
+
 
 class CodexConfigurator(HarnessConfigurator):
     name = "codex"
@@ -73,5 +76,15 @@ class CodexConfigurator(HarnessConfigurator):
                     candidates.append((started_at, payload["id"]))
             except (json.JSONDecodeError, KeyError, OSError, TypeError):
                 continue
-        candidates.sort(key=lambda t: t[0])
+        if len(candidates) > 1:
+            # Ambiguous: more than one Codex rollout matches this cwd + time
+            # window (e.g. a second Codex started in the same project). Guessing
+            # risks storing the wrong conversation id, so keep the placeholder.
+            log.warning(
+                "capture_session_id: %d rollouts match cwd=%s since=%s; refusing to guess",
+                len(candidates),
+                project_path,
+                since,
+            )
+            return None
         return candidates[0][1] if candidates else None

tests/test_harnesses.py

@@ -1,7 +1,6 @@
 import json
 import os
 import time
-from datetime import UTC, datetime
 from pathlib import Path
 from unittest.mock import patch
 
@@ -184,57 +183,25 @@ def test_codex_capture_accepts_file_after_since(tmp_path):
     assert result == "new-id"
 
 
-def test_codex_capture_first_post_since_cwd_match_wins(tmp_path):
-    """Among multiple post-since rollouts, the one started nearest since wins."""
+def test_codex_capture_ambiguous_returns_none(tmp_path):
+    """Two rollouts match cwd + since window -> refuse to guess, return None."""
     sessions_dir = tmp_path / ".codex" / "sessions" / "dir"
     sessions_dir.mkdir(parents=True)
 
-    rollout_older = sessions_dir / "rollout-older.jsonl"
-    rollout_newer = sessions_dir / "rollout-newer.jsonl"
-    _write_rollout(rollout_older, "older-id", "/projects/foo")
-    _write_rollout(rollout_newer, "newer-id", "/projects/foo")
+    rollout_a = sessions_dir / "rollout-a.jsonl"
+    rollout_b = sessions_dir / "rollout-b.jsonl"
+    _write_rollout(rollout_a, "id-a", "/projects/foo")
+    _write_rollout(rollout_b, "id-b", "/projects/foo")
 
     now = time.time()
     since = now - 120
-    os.utime(rollout_older, (now - 30, now - 30))
-    os.utime(rollout_newer, (now - 10, now - 10))
+    os.utime(rollout_a, (now - 30, now - 30))
+    os.utime(rollout_b, (now - 10, now - 10))
 
     c = CodexConfigurator()
     with patch("hqt.harnesses.configurators.codex.Path.home", return_value=tmp_path):
         result = c.capture_session_id(Path("/projects/foo"), since)
-    assert result == "older-id"
-
-
-def test_codex_capture_prefers_started_nearest_since_over_newest_file(tmp_path):
-    """Late capture should match the Codex session spawned at since, not a later same-cwd session."""
-    sessions_dir = tmp_path / ".codex" / "sessions" / "dir"
-    sessions_dir.mkdir(parents=True)
-
-    target = sessions_dir / "rollout-target.jsonl"
-    unrelated_later = sessions_dir / "rollout-later.jsonl"
-
-    since = datetime(2026, 6, 10, 21, 9, 15, tzinfo=UTC).timestamp()
-    _write_rollout(
-        target,
-        "target-id",
-        "/projects/foo",
-        timestamp="2026-06-10T21:09:16.000Z",
-    )
-    _write_rollout(
-        unrelated_later,
-        "later-id",
-        "/projects/foo",
-        timestamp="2026-06-10T21:45:45.000Z",
-    )
-
-    now = time.time()
-    os.utime(target, (now - 60, now - 60))
-    os.utime(unrelated_later, (now, now))
-
-    c = CodexConfigurator()
-    with patch("hqt.harnesses.configurators.codex.Path.home", return_value=tmp_path):
-        result = c.capture_session_id(Path("/projects/foo"), since)
-    assert result == "target-id"
+    assert result is None
 
 
 def test_codex_capture_skips_non_matching_cwd_picks_older_matching(tmp_path):