fix(wiki): basic conflict detection in CompileReport

Add _detect_conflicts() using adversative keyword heuristic (but,
however, in contrast, …) between chunks of different bibkeys; results
populate CompileReport.conflicts and appear in wiki/log.md.
Also add CompileReport.quarantined field (used by Fix 2).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/wiki/test_check.py

@@ -161,3 +161,67 @@ def test_wiki_check_index_and_log_ignored(
     assert result.exit_code == 0, (
         f"index.md / log.md should be excluded. exit={result.exit_code}, out={result.output}"
     )
+
+
+def test_wiki_check_exit_2_when_draft_not_empty(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """codex wiki check exits 2 when wiki/draft/ is non-empty (quarantined pages)."""
+    wiki = tmp_path / "wiki"
+    wiki.mkdir()
+    draft = wiki / "draft"
+    draft.mkdir()
+
+    (draft / "bad-concept.md").write_text(
+        "# Bad Concept\n\n⚠ Ungrounded hallucination. [FakeBib2025 #chunk 0]\n",
+        encoding="utf-8",
+    )
+
+    from unittest.mock import MagicMock
+
+    from codex.config import Settings
+
+    mock_settings = MagicMock(spec=Settings)
+    mock_settings.wiki_dir = str(wiki)
+    monkeypatch.setattr("codex.cli.get_settings", lambda: mock_settings, raising=False)
+
+    runner = CliRunner()
+    result = runner.invoke(app, ["wiki", "check", "--output-dir", str(wiki)])
+    assert result.exit_code == 2, (
+        f"Expected exit 2 (quarantined pages), got {result.exit_code}. Output: {result.output}"
+    )
+
+
+def test_wiki_check_exit_2_takes_priority_over_exit_1(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Exit 2 (quarantined) takes priority over exit 1 (ungrounded in wiki/)."""
+    wiki = tmp_path / "wiki"
+    wiki.mkdir()
+    draft = wiki / "draft"
+    draft.mkdir()
+
+    # Main wiki with ungrounded claim
+    (wiki / "concept-a.md").write_text(
+        "# Concept A\n\n⚠ Ungrounded claim. [SomeBib #chunk 0]\n",
+        encoding="utf-8",
+    )
+    # Draft with quarantined page
+    (draft / "concept-b.md").write_text(
+        "# Concept B\n\nQuarantined content.\n",
+        encoding="utf-8",
+    )
+
+    from unittest.mock import MagicMock
+
+    from codex.config import Settings
+
+    mock_settings = MagicMock(spec=Settings)
+    mock_settings.wiki_dir = str(wiki)
+    monkeypatch.setattr("codex.cli.get_settings", lambda: mock_settings, raising=False)
+
+    runner = CliRunner()
+    result = runner.invoke(app, ["wiki", "check", "--output-dir", str(wiki)])
+    assert result.exit_code == 2