Task flow engine implementation

migrations/versions/r5m6n7o8p9q0_workstream_status_string.py

@@ -0,0 +1,48 @@
+"""convert workstream status enum to string
+
+Revision ID: r5m6n7o8p9q0
+Revises: q4l5m6n7o8p9
+Create Date: 2026-05-01
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = "r5m6n7o8p9q0"
+down_revision = "q4l5m6n7o8p9"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.alter_column("workstreams", "status", server_default=None)
+    op.alter_column(
+        "workstreams",
+        "status",
+        existing_type=sa.Enum(
+            "active", "blocked", "completed", "archived", name="workstreamstatus"
+        ),
+        type_=sa.String(length=20),
+        existing_nullable=False,
+        postgresql_using="status::text",
+        server_default="active",
+    )
+    op.execute("DROP TYPE IF EXISTS workstreamstatus")
+
+
+def downgrade() -> None:
+    op.execute("UPDATE workstreams SET status = 'active' WHERE status = 'todo'")
+    op.alter_column("workstreams", "status", server_default=None)
+    workstream_status = sa.Enum(
+        "active", "blocked", "completed", "archived", name="workstreamstatus"
+    )
+    workstream_status.create(op.get_bind(), checkfirst=True)
+    op.alter_column(
+        "workstreams",
+        "status",
+        existing_type=sa.String(length=20),
+        type_=workstream_status,
+        existing_nullable=False,
+        postgresql_using="status::workstreamstatus",
+        server_default="active",
+    )