diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 63632be3a..5e7d45efc 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -64,10 +64,31 @@ jobs:
           # Surface symptom: every test fails with "Code: 194 REQUIRED_PASSWORD". Setting
           # CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT=1 + CLICKHOUSE_SKIP_USER_SETUP=1 keeps the
           # default-user-passwordless path open without baking a credential into the workflow.
+          # Use the same server overrides as the ClickHouse nightly job (`.claude/clickhouse-config/`).
+          # Without `mutations_sync = 2` an `ALTER ... DELETE` can finish between the two reads of one
+          # oracle check, which then reports a mismatch that is only a race (e.g. 132 rows vs 0 rows
+          # after `ALTER TABLE t0 DELETE WHERE <true constant>`). The files with `<profiles>` go to
+          # `users.d`, the rest to `config.d`. Each file is mounted separately, so the directories that
+          # the entrypoint writes to stay writable.
+          CONFIG_DIR="$PWD/.claude/clickhouse-config"
+          MOUNTS=()
+          for f in "$CONFIG_DIR"/*.xml; do
+            if grep -q '<profiles>' "$f"; then
+              MOUNTS+=(-v "$f:/etc/clickhouse-server/users.d/$(basename "$f"):ro")
+            else
+              MOUNTS+=(-v "$f:/etc/clickhouse-server/config.d/$(basename "$f"):ro")
+            fi
+          done
           docker run --ulimit nofile=262144:262144 --name clickhouse-server -p8123:8123 -d \
             -e CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT=1 -e CLICKHOUSE_SKIP_USER_SETUP=1 \
+            "${MOUNTS[@]}" \
             clickhouse/clickhouse-server:head
           until curl -sf http://127.0.0.1:8123/ping 2>/dev/null; do sleep 1; done
+          # Fail here rather than in a flaky oracle if the overrides did not take effect.
+          SETTINGS=$(curl -sf http://127.0.0.1:8123/ --data-binary \
+            "SELECT getSetting('mutations_sync'), getSetting('alter_sync'), getSetting('async_insert') FORMAT TSV")
+          echo "mutations_sync, alter_sync, async_insert: $SETTINGS"
+          test "$SETTINGS" = "$(printf '2\t2\tfalse')"
       - name: Run Tests
         run: CLICKHOUSE_AVAILABLE=true mvn -Djacoco.skip=true -Dtest=ClickHouseBinaryComparisonOperationTest,TestClickHouse,ClickHouseOperatorsVisitorTest,ClickHouseToStringVisitorTest,ClickHouseTypeTest,ClickHouseTypeParserTest,ClickHouseTypeGenerationTest,ClickHouseCastExtensionTest,ClickHouseCODDTestFilterTest,ClickHouseCERTGeneratorTest,ClickHouseTableGeneratorTest test
       - name: Show fatal errors