fix: harden strategy set migration upgrade

docs/db-schema-spec.md

@@ -168,5 +168,5 @@ When schema changes:
 | Revision ID | File | Summary |
 |---|---|---|
 | 20260403_0001 | migrations/versions/20260403_0001_initial_portfolio_schema.py | Initial schema for strategy sets, portfolios, ledger, indexes, optional hypertable |
-| 20260403_0002 | migrations/versions/20260403_0002_strategy_set_columns.py | Rename `strategy_name`->`name`, `strategy_config`->`config`, add unique `nick` |
+| 20260403_0002 | migrations/versions/20260403_0002_strategy_set_columns.py | Rename `strategy_name`->`name`, `strategy_config`->`config`, add unique `nick`, handle legacy unnamed unique constraint |
 | 20260403_0003 | migrations/versions/20260403_0003_portfolio_strategy_refs.py | Remove embedded portfolio strategy fields, add `active_strategy_id` and `avabile_strategies` |

migrations/versions/20260403_0002_strategy_set_columns.py

@@ -17,6 +17,33 @@ branch_labels = None
 depends_on = None
 
 
+def _drop_unique_constraint_for_columns(table_name: str, columns: tuple[str, ...]) -> None:
+    bind = op.get_bind()
+    rows = bind.execute(
+        sa.text(
+            """
+            SELECT c.conname,
+                   array_agg(a.attname ORDER BY u.ord) AS column_names
+            FROM pg_constraint c
+            JOIN pg_class t ON t.oid = c.conrelid
+            JOIN pg_namespace n ON n.oid = t.relnamespace
+            JOIN unnest(c.conkey) WITH ORDINALITY AS u(attnum, ord) ON TRUE
+            JOIN pg_attribute a ON a.attrelid = t.oid AND a.attnum = u.attnum
+            WHERE c.contype = 'u'
+              AND n.nspname = current_schema()
+              AND t.relname = :table_name
+            GROUP BY c.conname
+            """
+        ),
+        {"table_name": table_name},
+    )
+    expected = list(columns)
+    for row in rows:
+        if list(row.column_names) == expected:
+            op.drop_constraint(row.conname, table_name, type_="unique")
+            return
+
+
 def upgrade() -> None:
     op.add_column("strategy_sets", sa.Column("name", sa.Text(), nullable=True))
     op.add_column("strategy_sets", sa.Column("config", sa.Text(), nullable=True, server_default=""))
@@ -38,7 +65,7 @@ def upgrade() -> None:
     op.alter_column("strategy_sets", "config", nullable=False)
     op.alter_column("strategy_sets", "nick", nullable=False)
 
-    op.drop_constraint("uq_strategy_sets_name_config", "strategy_sets", type_="unique")
+    _drop_unique_constraint_for_columns("strategy_sets", ("strategy_name", "strategy_config"))
     op.create_unique_constraint("uq_strategy_sets_name_config", "strategy_sets", ["name", "config"])
     op.create_unique_constraint("uq_strategy_sets_nick", "strategy_sets", ["nick"])
 
@@ -64,8 +91,8 @@ def downgrade() -> None:
     op.alter_column("strategy_sets", "strategy_name", nullable=False)
     op.alter_column("strategy_sets", "strategy_config", nullable=False)
 
-    op.drop_constraint("uq_strategy_sets_nick", "strategy_sets", type_="unique")
+    _drop_unique_constraint_for_columns("strategy_sets", ("nick",))
-    op.drop_constraint("uq_strategy_sets_name_config", "strategy_sets", type_="unique")
+    _drop_unique_constraint_for_columns("strategy_sets", ("name", "config"))
     op.create_unique_constraint("uq_strategy_sets_name_config", "strategy_sets", ["strategy_name", "strategy_config"])
 
     op.drop_column("strategy_sets", "nick")