feat(agents): Add task assignment and comments functionality

backend/alembic/versions/8045fbfb157f_add_task_assigned_agent.py

@@ -0,0 +1,36 @@
+"""add task assigned agent
+
+Revision ID: 8045fbfb157f
+Revises: 6df47d330227
+Create Date: 2026-02-04 17:28:57.465934
+
+"""
+from __future__ import annotations
+
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = '8045fbfb157f'
+down_revision = '6df47d330227'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.execute(
+        "ALTER TABLE tasks ADD COLUMN IF NOT EXISTS assigned_agent_id UUID"
+    )
+    op.execute(
+        "ALTER TABLE tasks ADD CONSTRAINT IF NOT EXISTS tasks_assigned_agent_id_fkey "
+        "FOREIGN KEY (assigned_agent_id) REFERENCES agents(id)"
+    )
+
+
+def downgrade() -> None:
+    op.execute(
+        "ALTER TABLE tasks DROP CONSTRAINT IF EXISTS tasks_assigned_agent_id_fkey"
+    )
+    op.execute(
+        "ALTER TABLE tasks DROP COLUMN IF EXISTS assigned_agent_id"
+    )

backend/alembic/versions/b9d22e2a4d50_add_task_comments_index.py

@@ -0,0 +1,29 @@
+"""add task comments index
+
+Revision ID: b9d22e2a4d50
+Revises: 8045fbfb157f
+Create Date: 2026-02-04 17:32:06.204331
+
+"""
+from __future__ import annotations
+
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = 'b9d22e2a4d50'
+down_revision = '8045fbfb157f'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.execute(
+        "CREATE INDEX IF NOT EXISTS ix_activity_events_task_comment "
+        "ON activity_events (task_id, created_at) "
+        "WHERE event_type = 'task.comment'"
+    )
+
+
+def downgrade() -> None:
+    op.execute("DROP INDEX IF EXISTS ix_activity_events_task_comment")