merge this (#4759)

* wait I forgot to comit locally

* cp the entire core directory and then rm the .git subdir

alembic/versions/341068089f14_add_preserve_on_migration_to_block.py

@@ -0,0 +1,40 @@
+"""add preserve_on_migration to block
+
+Revision ID: 341068089f14
+Revises: 348214cbc081
+Create Date: 2025-05-29 10:39:44.494643
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+
+from alembic import op
+from letta.settings import settings
+
+# revision identifiers, used by Alembic.
+revision: str = "341068089f14"
+down_revision: Union[str, None] = "348214cbc081"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Skip this migration for SQLite
+    if not settings.letta_pg_uri_no_default:
+        return
+
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column("block", sa.Column("preserve_on_migration", sa.Boolean(), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # Skip this migration for SQLite
+    if not settings.letta_pg_uri_no_default:
+        return
+
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column("block", "preserve_on_migration")
+    # ### end Alembic commands ###