fix(schedules): use stable handles for run schedules

Move schedule authorization and mutations to immutable row identifiers while keeping name-based aliases for convenience.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: jromualdez-scale

agentex/database/migrations/alembic/versions/2026_07_08_1626_schedule_identity_id_handles_9a4b8c7d6e5f.py

@@ -0,0 +1,46 @@
+"""move run schedule identity to row id
+
+Revision ID: 9a4b8c7d6e5f
+Revises: e7f8a9b0c1d2
+Create Date: 2026-07-08 16:26:00.000000
+
+Switches schedule names from reserved external handles to mutable labels by
+making the name uniqueness constraint apply only to active rows. Schema-only and
+idempotent: index creation/drop use CONCURRENTLY with IF EXISTS / IF NOT EXISTS.
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "9a4b8c7d6e5f"
+down_revision: str | None = "e7f8a9b0c1d2"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    with op.get_context().autocommit_block():
+        op.execute(
+            "CREATE UNIQUE INDEX CONCURRENTLY IF NOT EXISTS "
+            "uq_agent_run_schedules_active_agent_name "
+            "ON agent_run_schedules (agent_id, name) "
+            "WHERE deleted_at IS NULL"
+        )
+        op.execute(
+            "DROP INDEX CONCURRENTLY IF EXISTS uq_agent_run_schedules_agent_name"
+        )
+
+
+def downgrade() -> None:
+    with op.get_context().autocommit_block():
+        op.execute(
+            "CREATE UNIQUE INDEX CONCURRENTLY IF NOT EXISTS "
+            "uq_agent_run_schedules_agent_name "
+            "ON agent_run_schedules (agent_id, name)"
+        )
+        op.execute(
+            "DROP INDEX CONCURRENTLY IF EXISTS "
+            "uq_agent_run_schedules_active_agent_name"
+        )