agent v0.36.0: guest boot-id on /disks (deterministic guest-reboot recreate)

GET /disks emits guest_boot_id = <host-btime>-<guest-init-starttime>: changes on
every guest/host boot, stable across controller-only restarts. The controller
persists it + deterministically recreates drive-backed apps on change (replaces
the timed state-sample). Non-hollow parser test + companion.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/localapi/disks.go

@@ -78,6 +78,9 @@ type GuestAttacher interface {
 	// GuestSeesMount reports whether vmid's guest sees `path` as a mount in its own namespace (the
 	// guest-usable signal — distinct from the host having the bind). Backs BoundUnderParent.
 	GuestSeesMount(ctx context.Context, vmid int, path string) bool
+	// GuestBootID returns a token that changes on every guest boot (host or guest) but is stable across a
+	// controller-only restart — the deterministic guest-reboot signal the controller recreates apps on.
+	GuestBootID(ctx context.Context, vmid int) string
 	// AttachBind is the LEGACY per-drive `pct set -mpN` bind (pre-intermediary). Retained for the
 	// transition; new attaches use AttachDrive.
 	AttachBind(ctx context.Context, vmid int, mountKey, where string) error
@@ -202,7 +205,13 @@ func (s *Server) handleDisks(w http.ResponseWriter, r *http.Request, vmid int) {
 		}
 		out = append(out, di)
 	}
-	writeOK(w, map[string]any{"vmid": vmid, "disks": out})
+	// Guest boot-id (intermediary model): changes on every guest boot, stable across controller restarts.
+	// The controller persists it and deterministically recreates drive-backed apps when it changes.
+	bootID := ""
+	if s.guestAttach != nil {
+		bootID = s.guestAttach.GuestBootID(r.Context(), vmid)
+	}
+	writeOK(w, map[string]any{"vmid": vmid, "disks": out, "guest_boot_id": bootID})
 }
 
 type assignRequest struct {