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>

codex/wiki.py

@@ -77,6 +77,7 @@ class CompileReport:
     skipped: list[str] = field(default_factory=list)  # slugs skipped (unchanged)
     ungrounded: list[tuple[str, str]] = field(default_factory=list)  # (slug, claim_text)
     conflicts: list[tuple[str, str, str]] = field(default_factory=list)  # (slug, bibkey1, bibkey2)
+    quarantined: list[str] = field(default_factory=list)  # slugs written to wiki/draft/
 
 
 # ---------------------------------------------------------------------------
@@ -279,6 +280,51 @@ def _run_grounding_guard(
     return claims
 
 
+# ---------------------------------------------------------------------------
+# Conflict detection (MVP: keyword-based signal)
+# ---------------------------------------------------------------------------
+
+_CONFLICT_KEYWORDS = re.compile(
+    r"\b(but|however|in contrast|contradicts|on the other hand|unlike|whereas)\b",
+    re.IGNORECASE,
+)
+
+
+def _detect_conflicts(
+    slug: str,
+    chunks: list[dict[str, Any]],
+) -> list[tuple[str, str, str]]:
+    """Detect potential conflicts between chunks for the same concept (MVP).
+
+    Looks for adversative keywords ("but", "however", "in contrast", …) in
+    pairs of chunks from *different* bibkeys.  Returns a list of
+    ``(slug, bibkey1, bibkey2)`` triples for each conflicting pair found.
+    """
+    conflicts: list[tuple[str, str, str]] = []
+    # Group chunks by bibkey
+    by_bib: dict[str, list[str]] = {}
+    for chunk in chunks:
+        bk = str(chunk.get("bibkey") or "")
+        if bk:
+            by_bib.setdefault(bk, []).append(chunk["content"])
+
+    bibkeys = list(by_bib.keys())
+    for i, bk1 in enumerate(bibkeys):
+        for bk2 in bibkeys[i + 1 :]:
+            # Check if any chunk from bk1 contains a conflict keyword
+            # and any chunk from bk2 also does — heuristic signal only
+            bk1_has_conflict = any(
+                _CONFLICT_KEYWORDS.search(c) for c in by_bib[bk1]
+            )
+            bk2_has_conflict = any(
+                _CONFLICT_KEYWORDS.search(c) for c in by_bib[bk2]
+            )
+            if bk1_has_conflict and bk2_has_conflict:
+                conflicts.append((slug, bk1, bk2))
+
+    return conflicts
+
+
 # ---------------------------------------------------------------------------
 # Cross-reference injection
 # ---------------------------------------------------------------------------
@@ -598,17 +644,32 @@ def compile_all(
             wiki_dir=wiki_dir,
         )
 
-        # Write page to disk
-        page_path = wiki_dir / f"{concept.slug}.md"
-        page_path.write_text(page.markdown, encoding="utf-8")
-
         # Collect ungrounded claims for the report
         for claim in page.claims:
             if not claim.grounded:
                 report.ungrounded.append((concept.slug, claim.text))
 
-        state[concept.slug] = page.chunk_hash
-        report.compiled.append(concept.slug)
+        # Detect conflicts between chunks from different bibkeys
+        report.conflicts.extend(_detect_conflicts(concept.slug, chunks))
+
+        # Quarantine check: compute grounding rate
+        total_claims = len(page.claims)
+        grounded_claims = sum(1 for c in page.claims if c.grounded)
+        grounding_rate = grounded_claims / total_claims if total_claims > 0 else 0.0
+
+        if total_claims > 0 and grounding_rate < settings.wiki_min_grounding_rate:
+            # Quarantine: write to wiki/draft/ instead of wiki/
+            draft_dir = wiki_dir / "draft"
+            draft_dir.mkdir(parents=True, exist_ok=True)
+            page_path = draft_dir / f"{concept.slug}.md"
+            page_path.write_text(page.markdown, encoding="utf-8")
+            report.quarantined.append(concept.slug)
+        else:
+            # Write page to wiki/
+            page_path = wiki_dir / f"{concept.slug}.md"
+            page_path.write_text(page.markdown, encoding="utf-8")
+            state[concept.slug] = page.chunk_hash
+            report.compiled.append(concept.slug)
 
     _save_compile_state(state_path, state)
     write_index([_page_summary(slug, wiki_dir) for slug in list(state.keys())])
@@ -701,6 +762,11 @@ def append_log(
         entry_lines.append("**⚠ Ungrounded claims:**")
         for slug, text in report.ungrounded:
             entry_lines.append(f"- `{slug}`: {text[:120]}")
+    if report.quarantined:
+        entry_lines.append("")
+        entry_lines.append("**QUARANTINED** (grounding rate < threshold → wiki/draft/):")
+        for slug in report.quarantined:
+            entry_lines.append(f"- `{slug}`")
     if report.conflicts:
         entry_lines.append("")
         entry_lines.append("**⚠ Conflicts detected:**")