@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/bytebase/omni/tidb/ast"
+	pingcapast "github.com/pingcap/tidb/pkg/parser/ast"
 
 	"github.com/bytebase/bytebase/backend/common"
 	storepb "github.com/bytebase/bytebase/backend/generated-go/store"
@@ -85,12 +86,46 @@ func (*StatementPriorBackupCheckAdvisor) Check(ctx context.Context, checkCtx adv
 		})
 	}
 
+	// Cumulative #30 Codex-fix-1f: DDL detection MUST go through
+	// pingcap (`getTiDBNodes`), not omni (`getTiDBOmniNodes`).
+	// Reason: invariant #2 soft-fail at the omni wrapper silently
+	// drops Tier-4-deferred grammar (Sequence trio, FlashBackDatabase,
+	// FlashBackTable). For a safety gate, that's a real regression —
+	// pingcap's full DDLNode interface catches all 22 implementers
+	// via `ddlNode` struct embedding. The omni path is still used
+	// below for per-table DML-mixing detection (where omni AST shape
+	// is required); DDL detection sidesteps omni's grammar gaps via
+	// the pingcap-bridge path.
+	//
+	// Architectural note: this dual-path approach mirrors mysql's
+	// analog (mysqlparser.ExtractTables + isOmniDDL). Eight rounds
+	// of Codex catches on omni-only DDL enumeration (cumulative #30
+	// Codex-fix-1c through 1e) demonstrated the brittle-enumeration
+	// pattern; switching DDL detection to pingcap's authoritative
+	// DDLNode interface eliminates the enumeration entirely.
+	pingcapStmts, err := getTiDBNodes(checkCtx)
+	if err != nil {
+		return nil, err
+	}
+	for _, p := range pingcapStmts {
+		if _, isDDL := p.(pingcapast.DDLNode); isDDL {
+			adviceList = append(adviceList, &storepb.Advice{
+				Status:        level,
+				Title:         title,
+				Content:       "Prior backup cannot deal with mixed DDL and DML statements",
+				Code:          code.BuiltinPriorBackupCheck.Int32(),
+				StartPosition: common.ConvertANTLRLineToPosition(p.OriginTextPosition()),
+			})
+		}
+	}
+
 	stmts, err := getTiDBOmniNodes(checkCtx)
 	if err != nil {
 		return nil, err
 	}
 
-	// 2. Mixed DDL + DML detection. Collect DML-by-table along the way.
+	// 2. Per-table DML mixing detection (omni path — needs full
+	// AST-shape access for SET-clause analysis).
 	// Cumulative #30 Codex-fix-2 (revised): resolve unqualified table
 	// references to a default database at EXTRACTION time, so the
 	// priorBackupTable.database field is always populated. This makes
@@ -115,15 +150,6 @@ func (*StatementPriorBackupCheckAdvisor) Check(ctx context.Context, checkCtx adv
 
 	for _, ostmt := range stmts {
 		node := ostmt.Node
-		if omniIsDDLStmt(node) {
-			adviceList = append(adviceList, &storepb.Advice{
-				Status:        level,
-				Title:         title,
-				Content:       "Prior backup cannot deal with mixed DDL and DML statements",
-				Code:          code.BuiltinPriorBackupCheck.Int32(),
-				StartPosition: common.ConvertANTLRLineToPosition(ostmt.FirstTokenLine()),
-			})
-		}
 		switch n := node.(type) {
 		case *ast.UpdateStmt:
 			// Cumulative #30 Codex-fix-1: derive UPDATE mutation
@@ -503,27 +529,11 @@ func omniResolveUnqualifiedSETColumn(colName string, distinctBases []priorBackup
 // the verified correct list. Unit tests in utils_test.go pin both
 // positive (DDL types that MUST return true) and negative (DML +
 // non-DDL utility types that must NOT) cases.
-// Cumulative #30 Codex-fix-1c: DropViewStmt + AlterDatabaseStmt are
-// DDL in pingcap. Initial port excluded both per peer's compile-time
-// `_ DDLNode = ...` grep, which missed the `ddlNode` struct embedding
-// at ast/base.go:81-88. Empirical: parsing `DROP VIEW v` yields
-// *ast.DropTableStmt in pingcap (already in our list) but
-// *ast.DropViewStmt in omni — excluding the latter was the real
-// regression. AlterDatabaseStmt empirically isDDLNode=true via the
-// embedding. Both added.
-func omniIsDDLStmt(node ast.Node) bool {
-	switch node.(type) {
-	case *ast.CreateTableStmt, *ast.AlterTableStmt, *ast.DropTableStmt,
-		*ast.CreateIndexStmt, *ast.DropIndexStmt,
-		*ast.CreateViewStmt, *ast.DropViewStmt,
-		*ast.CreateDatabaseStmt, *ast.AlterDatabaseStmt, *ast.DropDatabaseStmt,
-		*ast.TruncateStmt, // pingcap calls it TruncateTableStmt
-		*ast.RenameTableStmt,
-		*ast.CreatePlacementPolicyStmt, *ast.AlterPlacementPolicyStmt, *ast.DropPlacementPolicyStmt,
-		*ast.CreateResourceGroupStmt, *ast.AlterResourceGroupStmt, *ast.DropResourceGroupStmt,
-		*ast.OptimizeTableStmt, *ast.RepairTableStmt:
-		return true
-	default:
-		return false
-	}
-}
+// Note: omniIsDDLStmt previously enumerated omni's DDL types for
+// the advisor's DDL detection step. Removed in Codex-fix-1f after
+// eight rounds of enumeration corrections (cumulative #30 Codex-
+// fix-1c/1d/1e) revealed the omni-only path's fundamental gap with
+// pingcap's broader DDLNode interface (Tier-4-deferred grammar like
+// Sequence/FlashBack). DDL detection now uses pingcap's DDLNode
+// directly via the `getTiDBNodes` path; no per-type omni enumeration
+// to maintain. Lesson preserved in plan-doc cumulative #30.
@@ -268,6 +268,40 @@ func TestTiDBPriorBackupCheckAdvisor(t *testing.T) {
 				"db1.tech_book",
 			},
 		},
+		{
+			// Cumulative #30 Codex-fix-1f: Tier-4-deferred DDL
+			// (CREATE/ALTER/DROP SEQUENCE) is omni-rejected at
+			// parse time. Pre-fix-1f used omniIsDDLStmt on
+			// omni-parsed stmts → soft-fail skipped the SEQUENCE
+			// stmt → DDL detection missed → no mixed-DDL advice
+			// despite the DML+DDL mixing. Post-fix-1f: DDL
+			// detection uses pingcap's DDLNode interface via
+			// `getTiDBNodes` → pingcap parses CreateSequenceStmt
+			// successfully → DDL detected → advice fires.
+			name:            "CREATE SEQUENCE + UPDATE fires mixed DDL+DML via pingcap path (Codex-fix-1f)",
+			statement:       "CREATE SEQUENCE seq1 START 1 INCREMENT BY 1;\nUPDATE tech_book SET id = 1 WHERE id = 2;",
+			backupDBPresent: true,
+			wantContentSubstr: []string{
+				"mixed DDL and DML",
+			},
+		},
+		{
+			// Cumulative #30 Codex-fix-1f: FLASHBACK family is
+			// Tier-4-deferred grammar in omni. Pingcap handles
+			// FLASHBACK TABLE / FLASHBACK DATABASE as DDL via
+			// the DDLNode interface. Post-fix-1f: pingcap path
+			// catches it; pre-fix-1f silently skipped.
+			//
+			// Note: pingcap classifies FLASHBACK TABLE / DATABASE
+			// as DDL via ddlNode struct embedding. Verified by
+			// parse-test in batch 19 reshape investigation.
+			name:            "FLASHBACK TABLE + DELETE fires mixed DDL+DML via pingcap path (Codex-fix-1f)",
+			statement:       "FLASHBACK TABLE tech_book TO tech_book_old;\nDELETE FROM orders WHERE order_id = 5;",
+			backupDBPresent: true,
+			wantContentSubstr: []string{
+				"mixed DDL and DML",
+			},
+		},
 		{
 			// Cumulative #30 Codex-fix-1e: schema-aware column
 			// resolution for unqualified SET in multi-table UPDATE.
 
@@ -430,87 +430,12 @@ func TestOmniCharLength(t *testing.T) {
 	}
 }
 
-// TestOmniIsDDLStmt pins the DDL-type enumeration used by
-// builtin_prior_backup_check's mixed-DDL-and-DML detection.
-// Pingcap-tidb has an `ast.DDLNode` marker interface; omni has no
-// such interface, so we enumerate concrete DDL types. The enumeration
-// mirrors pingcap's DDLNode set (22 types per ast/ddl.go's
-// `_ DDLNode = &XxxStmt{}` declarations as of tidb v8.5.5), restricted
-// to types omni's grammar accepts today (drops 4 Tier-4-deferred:
-// Sequence trio + FlashBackDatabase).
-//
-// Both positive and negative pins are load-bearing — without the
-// negative cases, a future refactor could re-add over-inclusions
-// (e.g., CreateUserStmt) and tests would still pass. Initial batch
-// 19 had this exact mistake (over-enumerated User/Role/Function/
-// Tablespace as DDL when pingcap doesn't); pre-merge peer review
-// caught it, and the negative cases below pin the corrected contract.
-func TestOmniIsDDLStmt(t *testing.T) {
-	cases := []struct {
-		name string
-		node omniast.Node
-		want bool
-	}{
-		// Positive: pingcap DDLNode set (excluding Tier-4-deferred).
-		{"CreateTableStmt", &omniast.CreateTableStmt{}, true},
-		{"AlterTableStmt", &omniast.AlterTableStmt{}, true},
-		{"DropTableStmt", &omniast.DropTableStmt{}, true},
-		{"CreateIndexStmt", &omniast.CreateIndexStmt{}, true},
-		{"DropIndexStmt", &omniast.DropIndexStmt{}, true},
-		{"CreateViewStmt", &omniast.CreateViewStmt{}, true},
-		// Cumulative #30 Codex-fix-1c: DropViewStmt IS DDL (pingcap
-		// parses DROP VIEW under DropTableStmt which is DDL; omni
-		// splits to DropViewStmt — must classify as DDL for parity).
-		{"DropViewStmt (#30 Codex-fix-1c)", &omniast.DropViewStmt{}, true},
-		{"CreateDatabaseStmt", &omniast.CreateDatabaseStmt{}, true},
-		// Cumulative #30 Codex-fix-1c: AlterDatabaseStmt IS DDL via
-		// pingcap's ddlNode struct embedding (peer's compile-time
-		// `_ DDLNode = ...` grep missed embedding-based implementers).
-		{"AlterDatabaseStmt (#30 Codex-fix-1c)", &omniast.AlterDatabaseStmt{}, true},
-		{"DropDatabaseStmt", &omniast.DropDatabaseStmt{}, true},
-		{"TruncateStmt", &omniast.TruncateStmt{}, true},
-		{"RenameTableStmt", &omniast.RenameTableStmt{}, true},
-		{"CreatePlacementPolicyStmt", &omniast.CreatePlacementPolicyStmt{}, true},
-		{"AlterPlacementPolicyStmt", &omniast.AlterPlacementPolicyStmt{}, true},
-		{"DropPlacementPolicyStmt", &omniast.DropPlacementPolicyStmt{}, true},
-		{"CreateResourceGroupStmt", &omniast.CreateResourceGroupStmt{}, true},
-		{"AlterResourceGroupStmt", &omniast.AlterResourceGroupStmt{}, true},
-		{"DropResourceGroupStmt", &omniast.DropResourceGroupStmt{}, true},
-		{"OptimizeTableStmt", &omniast.OptimizeTableStmt{}, true},
-		{"RepairTableStmt", &omniast.RepairTableStmt{}, true},
-
-		// Negative — pingcap-tidb does NOT classify these as DDL.
-		// (Initial batch 19 over-enumerated these as true; pre-merge
-		// peer review caught; pins are load-bearing for that lesson.
-		// DropViewStmt and AlterDatabaseStmt were originally in this
-		// negative list per peer's compile-time grep, but Codex-fix-1c
-		// established they ARE DDL via runtime ddlNode-embedding
-		// verification — moved to positive list above.)
-		{"CreateUserStmt (privilege mgmt, not DDL)", &omniast.CreateUserStmt{}, false},
-		{"DropUserStmt", &omniast.DropUserStmt{}, false},
-		{"AlterUserStmt", &omniast.AlterUserStmt{}, false},
-		{"CreateRoleStmt", &omniast.CreateRoleStmt{}, false},
-		{"DropRoleStmt", &omniast.DropRoleStmt{}, false},
-		{"CreateFunctionStmt (procedural, not DDL)", &omniast.CreateFunctionStmt{}, false},
-		{"CreateTriggerStmt", &omniast.CreateTriggerStmt{}, false},
-		{"CreateEventStmt", &omniast.CreateEventStmt{}, false},
-		{"CreateTablespaceStmt", &omniast.CreateTablespaceStmt{}, false},
-		{"AlterTablespaceStmt", &omniast.AlterTablespaceStmt{}, false},
-		{"DropTablespaceStmt", &omniast.DropTablespaceStmt{}, false},
-		{"CreateServerStmt", &omniast.CreateServerStmt{}, false},
-
-		// Negative: DML and query.
-		{"UpdateStmt (DML)", &omniast.UpdateStmt{}, false},
-		{"DeleteStmt (DML)", &omniast.DeleteStmt{}, false},
-		{"InsertStmt (DML)", &omniast.InsertStmt{}, false},
-		{"SelectStmt (query)", &omniast.SelectStmt{}, false},
-
-		// Negative: nil.
-		{"nil", nil, false},
-	}
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			require.Equal(t, tc.want, omniIsDDLStmt(tc.node))
-		})
-	}
-}
+// TestOmniIsDDLStmt was REMOVED in cumulative #30 Codex-fix-1f:
+// the omniIsDDLStmt helper itself was removed when DDL detection
+// switched to pingcap's authoritative DDLNode interface via the
+// `getTiDBNodes` path. The omni-only enumeration was brittle (4
+// rounds of corrections across Codex-fix-1c/1d/1e) and fundamentally
+// gap-prone for Tier-4-deferred grammar (Sequence, FlashBackDatabase)
+// that omni's parser rejects but pingcap classifies as DDL. The
+// switch eliminates the enumeration. End-to-end coverage of the
+// DDL-detection path is now in TestTiDBPriorBackupCheckAdvisor.