feat(phase-30): add coverage snapshots, temporal comparison and auto re-testing (T-230 to T-232)

backend/alembic/versions/b016_add_retest_fields.py

@@ -0,0 +1,41 @@
+"""add_retest_fields
+
+Revision ID: b016retests
+Revises: b015snapshots
+Create Date: 2026-02-10 01:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision: str = "b016retests"
+down_revision: Union[str, None] = "b015snapshots"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "tests",
+        sa.Column(
+            "retest_of",
+            postgresql.UUID(as_uuid=True),
+            sa.ForeignKey("tests.id"),
+            nullable=True,
+        ),
+    )
+    op.add_column(
+        "tests",
+        sa.Column("retest_count", sa.Integer, server_default="0", nullable=False),
+    )
+    op.create_index("ix_tests_retest_of", "tests", ["retest_of"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_tests_retest_of", table_name="tests")
+    op.drop_column("tests", "retest_count")
+    op.drop_column("tests", "retest_of")