diff --git a/api/commands/rbac.py b/api/commands/rbac.py
new file mode 100644
index 0000000000..92cc6e26a6
--- /dev/null
+++ b/api/commands/rbac.py
@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+import click
+from sqlalchemy import select
+
+from core.db.session_factory import session_factory
+from models import TenantAccountJoin, TenantAccountRole
+from services.enterprise.rbac_service import ListOption, RBACService
+
+
+def _resolve_builtin_role_id(tenant_id: str, operator_account_id: str, legacy_role: str) -> str:
+    """Resolve a legacy workspace role to the current tenant's builtin RBAC role id.
+
+    The migration replays the old `TenantAccountJoin.role` values onto the
+    RBAC member-role binding API. Builtin RBAC roles are tenant-scoped and
+    identified by runtime ids, so the command must look them up per tenant.
+    """
+    expected_builtin_name = {
+        TenantAccountRole.OWNER.value: "所有者",
+        TenantAccountRole.ADMIN.value: "管理者",
+        TenantAccountRole.EDITOR.value: "编辑者",
+        TenantAccountRole.NORMAL.value: "普通用户",
+        TenantAccountRole.DATASET_OPERATOR.value: "知识库操作员",
+    }.get(legacy_role)
+    if not expected_builtin_name:
+        raise ValueError(f"Unsupported legacy workspace role: {legacy_role}")
+
+    roles = RBACService.Roles.list(
+        tenant_id=tenant_id,
+        account_id=operator_account_id,
+        options=ListOption(page_number=1, results_per_page=100),
+    ).data
+    for role in roles:
+        if role.is_builtin and role.category == "global_system_default" and role.name == expected_builtin_name:
+            return str(role.id)
+
+    raise ValueError(f"Builtin RBAC role not found for tenant={tenant_id}, legacy_role={legacy_role}")
+
+
+@click.command("rbac-migrate-member-roles", help="Migrate legacy workspace member roles into RBAC member-role bindings.")
+@click.option("--tenant-id", help="Only migrate a single workspace.")
+@click.option("--dry-run", is_flag=True, default=False, help="Preview the migration without writing RBAC bindings.")
+def migrate_member_roles_to_rbac(tenant_id: str | None, dry_run: bool) -> None:
+    """Backfill RBAC member-role bindings from legacy `TenantAccountJoin.role` data.
+
+    This is an offline migration command for workspaces that already have
+    members in the legacy role model but need matching records in the RBAC
+    member-role binding store.
+    """
+    click.echo(click.style("Starting RBAC member-role migration.", fg="green"))
+
+    with session_factory.create_session() as session:
+        stmt = select(TenantAccountJoin).order_by(TenantAccountJoin.tenant_id.asc(), TenantAccountJoin.id.asc())
+        if tenant_id:
+            stmt = stmt.where(TenantAccountJoin.tenant_id == tenant_id)
+
+        joins = list(session.scalars(stmt).all())
+
+    if not joins:
+        click.echo(click.style("No workspace members found for migration.", fg="yellow"))
+        return
+
+    owner_account_by_tenant: dict[str, str] = {}
+    resolved_role_ids: dict[tuple[str, str], str] = {}
+    migrated_count = 0
+
+    for join in joins:
+        workspace_id = str(join.tenant_id)
+        member_account_id = str(join.account_id)
+        legacy_role = str(join.role)
+
+        if workspace_id not in owner_account_by_tenant:
+            owner_join = next(
+                (
+                    item
+                    for item in joins
+                    if str(item.tenant_id) == workspace_id and str(item.role) == TenantAccountRole.OWNER.value
+                ),
+                None,
+            )
+            if not owner_join:
+                raise ValueError(f"Workspace owner not found for tenant={workspace_id}")
+            owner_account_by_tenant[workspace_id] = str(owner_join.account_id)
+
+        operator_account_id = owner_account_by_tenant[workspace_id]
+        cache_key = (workspace_id, legacy_role)
+        if cache_key not in resolved_role_ids:
+            resolved_role_ids[cache_key] = _resolve_builtin_role_id(workspace_id, operator_account_id, legacy_role)
+
+        resolved_role_id = resolved_role_ids[cache_key]
+        click.echo(
+            f"tenant={workspace_id} member={member_account_id} legacy_role={legacy_role} -> rbac_role_id={resolved_role_id}"
+        )
+
+        if dry_run:
+            continue
+
+        RBACService.MemberRoles.replace(
+            tenant_id=workspace_id,
+            account_id=operator_account_id,
+            member_account_id=member_account_id,
+            role_ids=[resolved_role_id],
+        )
+        migrated_count += 1
+
+    if dry_run:
+        click.echo(click.style("Dry run completed. No RBAC bindings were written.", fg="yellow"))
+    else:
+        click.echo(click.style(f"RBAC member-role migration completed. Migrated {migrated_count} members.", fg="green"))