fix(wiki): quarantine zero-citation pages instead of publishing (audit C-4)

compile_all's quarantine gate was guarded by `total_claims > 0`, so a page
with no parseable citations — including the LLM-outage case where
compile_concept returns an empty page — fell through to the publish branch and
was written to wiki/ + marked compiled. Such a page carries zero grounding
evidence.

Now: total_claims == 0 (or grounding_rate below threshold) quarantines and does
NOT update the compile-state, so a transient LLM failure retries next run
instead of freezing an empty/uncited page as 'compiled'. Empty bodies are
recorded but not written as draft files.

Regression test reproduces the exact bypass (uncited LLM output -> quarantined,
not published).

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

tests/wiki/test_compile.py

@@ -504,6 +504,47 @@ def test_log_append_records_skipped(
     assert "circle-packing" in content
 
 
+# ---------------------------------------------------------------------------
+# Audit C-4: zero-citation pages must NOT bypass the quarantine
+# ---------------------------------------------------------------------------
+
+
+def test_zero_citation_page_is_quarantined_not_published(
+    mock_retrieve: None,
+    mock_formulas: None,
+    mock_settings: Path,
+) -> None:
+    """A confident-but-uncited LLM response yields zero parseable claims
+    (grounding_rate 0.0). It must be quarantined — not written to wiki/ and
+    marked compiled. Regression for audit C-4: the old ``total_claims > 0``
+    guard let zero-claim (and LLM-outage empty) pages fall through to wiki/.
+    """
+    from codex.wiki import compile_all
+
+    (mock_settings / "concepts.yaml").write_text(
+        textwrap.dedent(
+            """\
+            concepts:
+              - slug: lobachevsky-function
+                title: Lobachevsky Function
+                aliases: [Milnor Lobachevsky]
+            """
+        ),
+        encoding="utf-8",
+    )
+    # No [BibKey] citations anywhere → zero claims → grounding_rate 0.0.
+    uncited = MockLLM(
+        "The Lobachevsky function is obviously central to all of geometry. "
+        "Every result follows from it. This paragraph cites nothing at all."
+    )
+
+    report = compile_all(changed_only=False, llm=uncited, output_dir=str(mock_settings))
+
+    assert "lobachevsky-function" in report.quarantined
+    assert "lobachevsky-function" not in report.compiled
+    assert not (mock_settings / "lobachevsky-function.md").exists()
+
+
 # ---------------------------------------------------------------------------
 # Idempotency: second compile without chunk change → no rewrite
 # ---------------------------------------------------------------------------