Development Notes

Execution Mode Architecture

Execution mode (dry-run, approval, auto, sunset) is configured per-disk-group on the Rules page. Each disk group has its own Mode field that governs how the engine acts on candidates within that group.

The DefaultDiskGroupMode field on PreferenceSet serves only as a template for newly auto-discovered disk groups. When the poller discovers a new mount path and creates a DiskGroup record, the group inherits the current DefaultDiskGroupMode value. After creation, the group's mode is independent of the global preference.

Key invariants

• Route handlers and orchestrators must never use prefs.DefaultDiskGroupMode for runtime decisions about existing groups. Always resolve the mode from the disk group itself.
• The only valid uses of DefaultDiskGroupMode are:
  1. DiskGroupService.Upsert() — setting mode on newly created groups
  2. Fallback paths where no disk group association exists (e.g., resolveCurrentMode() in deletion worker for legacy queue items without a DiskGroupID)
  3. Backup/restore compatibility
• The worker stats API returns diskGroupModes (a JSON map of group ID → mode) rather than a single global mode string.
• SSE events (engine_start, engine_complete) carry diskGroupModes for real-time UI updates.