diff --git a/mcp-server/src/legal_mcp/services/qa_validator.py b/mcp-server/src/legal_mcp/services/qa_validator.py
index 8b90040..7008daf 100644
--- a/mcp-server/src/legal_mcp/services/qa_validator.py
+++ b/mcp-server/src/legal_mcp/services/qa_validator.py
@@ -287,6 +287,50 @@ def check_sequential_numbering(blocks: list[dict]) -> dict:
     }
 
 
+async def check_citation_resolution(case_id: UUID, decision_id=None) -> dict:
+    """GAP-20/INV-AUD3: every cited case_law_id must resolve to the corpus.
+
+    Reads case_law_ids from the decision's write_block audit provenance and
+    verifies each resolves. Unresolvable → NON-BLOCKING warning + audit event.
+    """
+    from legal_mcp.services import audit
+
+    rows = await audit.get_audit_log(case_id=case_id, action="write_block", limit=200)
+    ids = set()
+    for r in rows:
+        details = r.get("details") or {}
+        if isinstance(details, str):
+            try:
+                details = json.loads(details)
+            except (ValueError, TypeError):
+                details = {}
+        for raw in (details.get("sources") or {}).get("case_law_ids", []):
+            try:
+                ids.add(UUID(str(raw)))
+            except (ValueError, TypeError):
+                pass
+
+    if not ids:
+        return {"name": "citation_resolution", "passed": True, "errors": [], "severity": "warning"}
+
+    res = await db.resolve_citation_case_law_ids(list(ids))
+    if not res["unresolved"]:
+        return {"name": "citation_resolution", "passed": True, "errors": [], "severity": "warning"}
+
+    await audit.log_action_safe(
+        "citation_unresolved", case_id=case_id,
+        details={"unresolved": [str(x) for x in res["unresolved"]]},
+    )
+    return {
+        "name": "citation_resolution",
+        "passed": False,
+        "severity": "warning",
+        "errors": [
+            f"{len(res['unresolved'])} ציטוטים אינם פתירים לקורפוס — דורש אימות יו\"ר",
+        ],
+    }
+
+
 # ── Main validation ───────────────────────────────────────────────
 
 async def validate_decision(case_id: UUID) -> dict:
@@ -334,6 +378,8 @@ async def validate_decision(case_id: UUID) -> dict:
         check_no_duplication(blocks),
         check_sequential_numbering(blocks),
     ])
+    # Async, non-blocking warning: citation→corpus resolution (GAP-20/INV-AUD3)
+    results.append(await check_citation_resolution(case_id, decision["id"]))
 
     critical_failures = sum(1 for r in results if not r["passed"] and r["severity"] == "critical")
     all_passed = all(r["passed"] for r in results)