v0.318.0: the internal data place, partitions, an honest whole-box backup offer (R-1084), sys_drive never offered (R-1082)

felhom.eu architecture/16 §4-§6 (build B). MinAgent 0.157.0 — the internal place and the partitions appear only when
agent >= 0.158.0 reports them. Tests red-proved; four parity fixtures refreshed (only the new lines).

Claude-Session: https://claude.ai/code/session_012qRErfCoiTkvDK9N5XHbzb

controller/internal/agentapi/client.go

@@ -357,12 +357,16 @@ type DiskInfo struct {
 	Smart *SmartSummary `json:"smart,omitempty"`
 	// Physical-disk identity (agent v0.157.0, `16` §3): kind, the keys of the physical disks under the place,
 	// proven|unknown + reason. Empty from an older agent or for an absent drive.
-	Kind           string   `json:"kind,omitempty"`
+	Kind           string   `json:"kind,omitempty"` // system | internal | disk | partition | network (felhom.eu `16` §3)
 	PhysicalDisks  []string `json:"physical_disks,omitempty"`
 	Identity       string   `json:"identity,omitempty"`
 	IdentityReason string   `json:"identity_reason,omitempty"`
 }
 
+// PlaceKindInternal is the agent's kind for the one-disk box's internal data place („Belső tárhely", agent ≥ 0.158.0,
+// felhom.eu architecture/16 §5): a host mount on the system disk, bound at /mnt/felhom-drives/belso.
+const PlaceKindInternal = "internal"
+
 // FSUUID returns the raw filesystem UUID from a "uuid:<…>" DurableID, or "" if this disk's identity
 // is not a filesystem UUID (network/lvm targets — not assignable as a host mount).
 func (d DiskInfo) FSUUID() string {
@@ -477,8 +481,34 @@ type DiskCandidate struct {
 	// mountpoint — sending it down the device-attach path would try to mount an in-guest path as if
 	// it were a raw device. See web/attach_sources.go for why the agent's scan cannot supply these.
 	AlreadyMounted bool `json:"already_mounted,omitempty"`
+	// Partitions (agent ≥ 0.158.0, felhom.eu architecture/16 §6): each partition of this disk as its own place —
+	// state empty („format this part"), filesystem („use this part" when mountable; format through the confirmed
+	// path), in_use (already a Felhom drive: shown, never offered). Absent from an older agent.
+	Partitions []CandidatePartition `json:"partitions,omitempty"`
+	// WholeDiskInUse is set by the CONTROLLER (never the agent) when a partition of this disk is a registered drive
+	// (R-542): the disk stays listed for its FREE parts only, and no whole-disk action is offered.
+	WholeDiskInUse bool `json:"whole_disk_in_use,omitempty"`
 }
 
+// CandidatePartition mirrors the agent's partition entry (felhom-agent internal/storage/partitions.go).
+type CandidatePartition struct {
+	Device    string `json:"device"`
+	Number    int    `json:"number,omitempty"`
+	SizeBytes int64  `json:"size_bytes"`
+	FSType    string `json:"fstype,omitempty"`
+	State     string `json:"state"` // empty | filesystem | in_use
+	Mountable bool   `json:"mountable"`
+	DurableID string `json:"durable_id,omitempty"` // uuid:<fs-uuid> — the attach key
+	MountedAt string `json:"mounted_at,omitempty"`
+}
+
+// Partition states (agent ≥ 0.158.0).
+const (
+	PartEmpty      = "empty"
+	PartFilesystem = "filesystem"
+	PartInUse      = "in_use"
+)
+
 // CandidatesResult mirrors GET /disks/candidates: disks free to enroll, split into initialize (all
 // unclaimed) and attach (the mountable-FS subset).
 type CandidatesResult struct {