Description

A sandbox with custom policy presets applied via policy --from-file / --from-dir loses them after snapshot restore (including snapshot restore --to <dst>). The restored sandbox keeps its built-in presets but none of the custom ones.

Root cause

snapshot create records applied policy presets into the rebuild manifest so they can be re-applied after destroy/recreate, because presets live in the gateway policy engine rather than on the sandbox filesystem. But it only captures the built-in preset names (policyPresets, from registry.policies):

• The RebuildManifest interface has policyPresets?: string[] but no field for custom presets.
• createBackup captures sb.policies only.
• snapshot restore reconciles policyPresets only.

Custom presets are tracked separately in registry.customPolicies (each CustomPolicyEntry carries the preset's full content), and they live in the same gateway-only location, so they are subject to the exact same loss on restore — but nothing captures or replays them. Result: custom policies are silently dropped.

Expected

snapshot restore re-applies custom policy presets just like built-in presets, so the restored sandbox's effective policy matches the snapshot.

Fix

Since CustomPolicyEntry.content is self-contained, capture customPolicies into the rebuild manifest and reconcile them on restore (re-apply by content via the existing custom-preset apply path, which also re-records them in the registry; remove any the snapshot did not record), mirroring how policyPresets are reconciled.