Enforce bounded operation guardrails

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a028de-e2c8-7732-8521-46a7fc5db82f

migrations/versions/0009_drop_legacy_task_instances.py

@@ -0,0 +1,57 @@
+"""retire legacy executor and gate-sounding audit column
+
+Revision ID: 0009
+Revises: 0008
+Create Date: 2026-08-23
+
+ACTIVITY-WP-0035-T07 — the disabled TaskExecutorWorkflow compatibility stub had
+no production executions and task_instances had zero production rows.
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects.postgresql import JSONB
+
+revision: str = "0009"
+down_revision: Union[str, Sequence[str], None] = "0008"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.drop_index("ix_task_instances_run_id", table_name="task_instances")
+    op.drop_table("task_instances")
+    op.alter_column(
+        "task_spawn_log",
+        "review_required",
+        new_column_name="review_advisory",
+    )
+
+
+def downgrade() -> None:
+    op.alter_column(
+        "task_spawn_log",
+        "review_advisory",
+        new_column_name="review_required",
+    )
+    op.create_table(
+        "task_instances",
+        sa.Column("id", sa.UUID(), nullable=False),
+        sa.Column("run_id", sa.UUID(), nullable=False),
+        sa.Column("type", sa.Text(), nullable=False),
+        sa.Column("params", JSONB(), nullable=False, server_default="{}"),
+        sa.Column("status", sa.Text(), nullable=False, server_default="pending"),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.ForeignKeyConstraint(
+            ["run_id"], ["activity_runs.run_id"], ondelete="CASCADE"
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index("ix_task_instances_run_id", "task_instances", ["run_id"])