Isolate multi-VM setup with deterministic device targeting

Makefile

@@ -8,6 +8,10 @@ CPU         ?= 8
 MEMORY      ?= 8192
 DISK_SIZE   ?= 64
 CFW_INPUT   ?= cfw_input
+RESTORE_UDID ?=
+RESTORE_ECID ?=
+IRECOVERY_ECID ?=
+SSH_PORT    ?= 2222
 
 # ─── Build info ──────────────────────────────────────────────────
 GIT_HASH    := $(shell git rev-parse --short HEAD 2>/dev/null || echo "unknown")
@@ -77,7 +81,7 @@ help:
 	@echo "  make cfw_install_dev         Install CFW mods via SSH (dev mode)"
 	@echo "  make cfw_install_jb          Install CFW + JB extensions (jetsam/procursus/basebin)"
 	@echo ""
-	@echo "Variables: VM_DIR=$(VM_DIR) CPU=$(CPU) MEMORY=$(MEMORY) DISK_SIZE=$(DISK_SIZE)"
+	@echo "Variables: VM_DIR=$(VM_DIR) CPU=$(CPU) MEMORY=$(MEMORY) DISK_SIZE=$(DISK_SIZE) SSH_PORT=$(SSH_PORT)"
 
 # ═══════════════════════════════════════════════════════════════════
 # Setup
@@ -208,10 +212,16 @@ fw_patch_jb:
 .PHONY: restore_get_shsh restore
 
 restore_get_shsh:
-	cd $(VM_DIR) && "$(CURDIR)/$(IDEVICERESTORE)" -e -y ./iPhone*_Restore -t
+	cd $(VM_DIR) && "$(CURDIR)/$(IDEVICERESTORE)" \
+		$(if $(RESTORE_UDID),-u $(RESTORE_UDID),) \
+		$(if $(RESTORE_ECID),-i $(RESTORE_ECID),) \
+		-e -y ./iPhone*_Restore -t
 
 restore:
-	cd $(VM_DIR) && "$(CURDIR)/$(IDEVICERESTORE)" -e -y ./iPhone*_Restore
+	cd $(VM_DIR) && "$(CURDIR)/$(IDEVICERESTORE)" \
+		$(if $(RESTORE_UDID),-u $(RESTORE_UDID),) \
+		$(if $(RESTORE_ECID),-i $(RESTORE_ECID),) \
+		-e -y ./iPhone*_Restore
 
 # ═══════════════════════════════════════════════════════════════════
 # Ramdisk
@@ -223,7 +233,8 @@ ramdisk_build:
 	cd $(VM_DIR) && $(PYTHON) "$(CURDIR)/$(SCRIPTS)/ramdisk_build.py" .
 
 ramdisk_send:
-	cd $(VM_DIR) && IRECOVERY="$(CURDIR)/$(IRECOVERY)" zsh "$(CURDIR)/$(SCRIPTS)/ramdisk_send.sh"
+	cd $(VM_DIR) && IRECOVERY="$(CURDIR)/$(IRECOVERY)" IRECOVERY_ECID="$(IRECOVERY_ECID)" \
+		zsh "$(CURDIR)/$(SCRIPTS)/ramdisk_send.sh"
 
 # ═══════════════════════════════════════════════════════════════════
 # CFW
@@ -232,10 +243,10 @@ ramdisk_send:
 .PHONY: cfw_install cfw_install_dev cfw_install_jb
 
 cfw_install:
-	cd $(VM_DIR) && zsh "$(CURDIR)/$(SCRIPTS)/cfw_install.sh" .
+	cd $(VM_DIR) && SSH_PORT="$(SSH_PORT)" zsh "$(CURDIR)/$(SCRIPTS)/cfw_install.sh" .
 
 cfw_install_dev:
-	cd $(VM_DIR) && zsh "$(CURDIR)/$(SCRIPTS)/cfw_install_dev.sh" .
+	cd $(VM_DIR) && SSH_PORT="$(SSH_PORT)" zsh "$(CURDIR)/$(SCRIPTS)/cfw_install_dev.sh" .
 
 cfw_install_jb:
-	cd $(VM_DIR) && zsh "$(CURDIR)/$(SCRIPTS)/cfw_install_jb.sh" .
+	cd $(VM_DIR) && SSH_PORT="$(SSH_PORT)" zsh "$(CURDIR)/$(SCRIPTS)/cfw_install_jb.sh" .

scripts/cfw_install.sh

@@ -29,7 +29,7 @@ CFW_INPUT="cfw_input"
 CFW_ARCHIVE="cfw_input.tar.zst"
 TEMP_DIR="$VM_DIR/.cfw_temp"
 
-SSH_PORT=2222
+SSH_PORT="${SSH_PORT:-2222}"
 SSH_PASS="alpine"
 SSH_USER="root"
 SSH_HOST="localhost"

scripts/cfw_install_dev.sh

@@ -29,7 +29,7 @@ CFW_INPUT="cfw_input"
 CFW_ARCHIVE="cfw_input.tar.zst"
 TEMP_DIR="$VM_DIR/.cfw_temp"
 
-SSH_PORT=2222
+SSH_PORT="${SSH_PORT:-2222}"
 SSH_PASS="alpine"
 SSH_USER="root"
 SSH_HOST="localhost"

scripts/cfw_install_jb.sh

@@ -35,7 +35,7 @@ CFW_JB_INPUT="cfw_jb_input"
 CFW_JB_ARCHIVE="cfw_jb_input.tar.zst"
 TEMP_DIR="$VM_DIR/.cfw_temp"
 
-SSH_PORT=2222
+SSH_PORT="${SSH_PORT:-2222}"
 SSH_PASS="alpine"
 SSH_USER="root"
 SSH_HOST="localhost"

scripts/ramdisk_send.sh

@@ -8,8 +8,26 @@
 set -euo pipefail
 
 IRECOVERY="${IRECOVERY:-irecovery}"
+IRECOVERY_ECID="${IRECOVERY_ECID:-}"
 RAMDISK_DIR="${1:-Ramdisk}"
 
+IRECOVERY_ARGS=()
+if [[ -n "$IRECOVERY_ECID" ]]; then
+    IRECOVERY_ECID="${IRECOVERY_ECID#0x}"
+    IRECOVERY_ECID="${IRECOVERY_ECID#0X}"
+    [[ "$IRECOVERY_ECID" =~ ^[0-9A-Fa-f]{1,16}$ ]] || {
+        echo "[-] Invalid IRECOVERY_ECID: ${IRECOVERY_ECID}"
+        exit 1
+    }
+    IRECOVERY_ECID="0x${IRECOVERY_ECID:u}"
+    IRECOVERY_ARGS=(-i "$IRECOVERY_ECID")
+    echo "[*] Using ECID selector for irecovery: ${IRECOVERY_ECID}"
+fi
+
+irecovery_cmd() {
+    "$IRECOVERY" "${IRECOVERY_ARGS[@]}" "$@"
+}
+
 if [[ ! -d "$RAMDISK_DIR" ]]; then
     echo "[-] Ramdisk directory not found: $RAMDISK_DIR"
     echo "    Run 'make ramdisk_build' first."
@@ -30,48 +48,48 @@ fi
 
 # 1. Load iBSS + iBEC (DFU → recovery)
 echo "  [1/8] Loading iBSS..."
-"$IRECOVERY" -f "$RAMDISK_DIR/iBSS.vresearch101.RELEASE.img4"
+irecovery_cmd -f "$RAMDISK_DIR/iBSS.vresearch101.RELEASE.img4"
 
 echo "  [2/8] Loading iBEC..."
-"$IRECOVERY" -f "$RAMDISK_DIR/iBEC.vresearch101.RELEASE.img4"
+irecovery_cmd -f "$RAMDISK_DIR/iBEC.vresearch101.RELEASE.img4"
-"$IRECOVERY" -c go
+irecovery_cmd -c go
 
 sleep 1
 
 # 2. Load SPTM
 echo "  [3/8] Loading SPTM..."
-"$IRECOVERY" -f "$RAMDISK_DIR/sptm.vresearch1.release.img4"
+irecovery_cmd -f "$RAMDISK_DIR/sptm.vresearch1.release.img4"
-"$IRECOVERY" -c firmware
+irecovery_cmd -c firmware
 
 # 3. Load TXM
 echo "  [4/8] Loading TXM..."
-"$IRECOVERY" -f "$RAMDISK_DIR/txm.img4"
+irecovery_cmd -f "$RAMDISK_DIR/txm.img4"
-"$IRECOVERY" -c firmware
+irecovery_cmd -c firmware
 
 # 4. Load trustcache
 echo "  [5/8] Loading trustcache..."
-"$IRECOVERY" -f "$RAMDISK_DIR/trustcache.img4"
+irecovery_cmd -f "$RAMDISK_DIR/trustcache.img4"
-"$IRECOVERY" -c firmware
+irecovery_cmd -c firmware
 
 # 5. Load ramdisk
 echo "  [6/8] Loading ramdisk..."
-"$IRECOVERY" -f "$RAMDISK_DIR/ramdisk.img4"
+irecovery_cmd -f "$RAMDISK_DIR/ramdisk.img4"
 sleep 2
-"$IRECOVERY" -c ramdisk
+irecovery_cmd -c ramdisk
 
 # 6. Load device tree
 echo "  [7/8] Loading device tree..."
-"$IRECOVERY" -f "$RAMDISK_DIR/DeviceTree.vphone600ap.img4"
+irecovery_cmd -f "$RAMDISK_DIR/DeviceTree.vphone600ap.img4"
-"$IRECOVERY" -c devicetree
+irecovery_cmd -c devicetree
 
 # 7. Load SEP
 echo "  [8/8] Loading SEP..."
-"$IRECOVERY" -f "$RAMDISK_DIR/sep-firmware.vresearch101.RELEASE.img4"
+irecovery_cmd -f "$RAMDISK_DIR/sep-firmware.vresearch101.RELEASE.img4"
-"$IRECOVERY" -c firmware
+irecovery_cmd -c firmware
 
 # 8. Load kernel and boot
 echo "  [*] Booting kernel..."
-"$IRECOVERY" -f "$KERNEL_IMG"
+irecovery_cmd -f "$KERNEL_IMG"
-"$IRECOVERY" -c bootx
+irecovery_cmd -c bootx
 
 echo "[+] Boot sequence complete. Device should be booting into ramdisk."

scripts/setup_machine.sh

@@ -17,7 +17,7 @@ cd "$PROJECT_ROOT"
 
 LOG_DIR="${PROJECT_ROOT}/setup_logs"
 DFU_LOG="${LOG_DIR}/boot_dfu.log"
-IPROXY_LOG="${LOG_DIR}/iproxy_2222.log"
+IPROXY_LOG=""
 
 DFU_PID=""
 IPROXY_PID=""
@@ -32,9 +32,16 @@ POST_RESTORE_KILL_DELAY="${POST_RESTORE_KILL_DELAY:-30}"
 POST_KILL_SETTLE_DELAY="${POST_KILL_SETTLE_DELAY:-5}"
 RAMDISK_SSH_TIMEOUT="${RAMDISK_SSH_TIMEOUT:-60}"
 RAMDISK_SSH_INTERVAL="${RAMDISK_SSH_INTERVAL:-2}"
-RAMDISK_SSH_PORT="${RAMDISK_SSH_PORT:-2222}"
+RAMDISK_SSH_PORT="${RAMDISK_SSH_PORT:-}"
 RAMDISK_SSH_USER="${RAMDISK_SSH_USER:-root}"
 RAMDISK_SSH_PASS="${RAMDISK_SSH_PASS:-alpine}"
+RAMDISK_SSH_PORT_EXPLICIT=0
+if [[ -n "$RAMDISK_SSH_PORT" ]]; then
+  RAMDISK_SSH_PORT_EXPLICIT=1
+fi
+
+DEVICE_UDID=""
+DEVICE_ECID=""
 JB_MODE=0
 DEV_MODE=0
 SKIP_PROJECT_SETUP=0
@@ -49,6 +56,92 @@ require_cmd() {
   command -v "$cmd" >/dev/null 2>&1 || die "Missing required command: $cmd"
 }
 
+normalize_ecid() {
+  local ecid="$1"
+  ecid="${ecid#0x}"
+  ecid="${ecid#0X}"
+  [[ "$ecid" =~ ^[0-9A-Fa-f]{1,16}$ ]] || return 1
+  printf "%016s" "${ecid:u}" | tr ' ' '0'
+}
+
+load_device_identity() {
+  local prediction_file="${VM_DIR_ABS}/udid-prediction.txt"
+  local timeout=30
+  local waited=0
+  local key value
+  local udid_ecid
+
+  while [[ ! -f "$prediction_file" && "$waited" -lt "$timeout" ]]; do
+    if [[ -n "$DFU_PID" ]] && ! kill -0 "$DFU_PID" 2>/dev/null; then
+      break
+    fi
+    sleep 1
+    (( waited++ ))
+  done
+
+  [[ -f "$prediction_file" ]] || die "Missing ${prediction_file}. Rebuild and run make boot_dfu to generate it."
+
+  DEVICE_UDID=""
+  DEVICE_ECID=""
+  while IFS='=' read -r key value; do
+    case "$key" in
+      UDID)
+        DEVICE_UDID="${value:u}"
+        ;;
+      ECID)
+        DEVICE_ECID="$(normalize_ecid "$value" || true)"
+        ;;
+    esac
+  done < "$prediction_file"
+
+  [[ "$DEVICE_UDID" =~ ^[0-9A-F]{8}-[0-9A-F]{16}$ ]] \
+    || die "Invalid UDID in ${prediction_file}: ${DEVICE_UDID}"
+
+  if [[ -z "$DEVICE_ECID" ]]; then
+    DEVICE_ECID="${DEVICE_UDID#*-}"
+  fi
+  [[ "$DEVICE_ECID" =~ ^[0-9A-F]{16}$ ]] \
+    || die "Invalid ECID in ${prediction_file}: ${DEVICE_ECID}"
+
+  udid_ecid="${DEVICE_UDID#*-}"
+  [[ "$udid_ecid" == "$DEVICE_ECID" ]] \
+    || die "UDID/ECID mismatch in ${prediction_file}: ${DEVICE_UDID} vs 0x${DEVICE_ECID}"
+
+  echo "[+] Device identity loaded: UDID=${DEVICE_UDID} ECID=0x${DEVICE_ECID}"
+}
+
+port_is_listening() {
+  local port="$1"
+  lsof -n -t -iTCP:"$port" -sTCP:LISTEN >/dev/null 2>&1
+}
+
+pick_random_ssh_port() {
+  local attempt port
+  for attempt in {1..200}; do
+    port=$((20000 + (RANDOM % 40000)))
+    if ! port_is_listening "$port"; then
+      echo "$port"
+      return 0
+    fi
+  done
+  return 1
+}
+
+choose_ramdisk_ssh_port() {
+  if [[ -n "$RAMDISK_SSH_PORT" ]]; then
+    [[ "$RAMDISK_SSH_PORT" == <-> ]] || die "RAMDISK_SSH_PORT must be an integer"
+    (( RAMDISK_SSH_PORT >= 1 && RAMDISK_SSH_PORT <= 65535 )) \
+      || die "RAMDISK_SSH_PORT out of range: ${RAMDISK_SSH_PORT}"
+    if port_is_listening "$RAMDISK_SSH_PORT"; then
+      die "RAMDISK_SSH_PORT ${RAMDISK_SSH_PORT} is already in use"
+    fi
+    return
+  fi
+
+  RAMDISK_SSH_PORT="$(pick_random_ssh_port)" \
+    || die "Failed to allocate a random local SSH forward port"
+}
+
 collect_vm_lock_pids() {
   local -a paths pids
   local path pid
@@ -329,12 +422,19 @@ wait_for_post_restore_reboot() {
 
 wait_for_recovery() {
   local irecovery="${PROJECT_ROOT}/.limd/bin/irecovery"
+  local -a query_args
   [[ -x "$irecovery" ]] || die "irecovery not found at $irecovery"
 
+  if [[ -n "$DEVICE_ECID" ]]; then
+    query_args=(-i "0x${DEVICE_ECID}")
+  else
+    query_args=()
+  fi
+
   echo "[*] Waiting for recovery/DFU endpoint..."
   local i
   for i in {1..90}; do
-    if "$irecovery" -q >/dev/null 2>&1; then
+    if "$irecovery" "${query_args[@]}" -q >/dev/null 2>&1; then
       echo "[+] Device endpoint is reachable"
       return
     fi
@@ -346,29 +446,28 @@ wait_for_recovery() {
   exit 1
 }
 
-start_iproxy_2222() {
+start_iproxy() {
   local iproxy_bin
-  local -a stale_pids
-  local pid
   iproxy_bin="${PROJECT_ROOT}/.limd/bin/iproxy"
   [[ -x "$iproxy_bin" ]] || die "iproxy not found at $iproxy_bin (run: make setup_libimobiledevice)"
+  [[ -n "$DEVICE_UDID" ]] || die "Device UDID is empty; cannot start isolated iproxy"
 
-  stale_pids=(${(@f)$(lsof -n -t -iTCP:2222 -sTCP:LISTEN 2>/dev/null || true)})
+  choose_ramdisk_ssh_port
-  if (( ${#stale_pids[@]} > 0 )); then
+
-    echo "[*] Found stale listener(s) on tcp/2222, terminating..."
+  if port_is_listening "$RAMDISK_SSH_PORT"; then
-    for pid in "${stale_pids[@]}"; do
+    if [[ "$RAMDISK_SSH_PORT_EXPLICIT" == "1" ]]; then
-      [[ -z "$pid" || "$pid" == "$$" ]] && continue
+      die "RAMDISK_SSH_PORT ${RAMDISK_SSH_PORT} is already in use"
-      kill_descendants "$pid"
+    fi
-      kill -9 "$pid" >/dev/null 2>&1 || true
+    RAMDISK_SSH_PORT="$(pick_random_ssh_port)" \
-    done
+      || die "Failed to allocate a free random local SSH forward port"
-    sleep 1
   fi
 
+  IPROXY_LOG="${LOG_DIR}/iproxy_${RAMDISK_SSH_PORT}.log"
   mkdir -p "$LOG_DIR"
   : > "$IPROXY_LOG"
 
-  echo "[*] Starting iproxy 2222 -> 22..."
+  echo "[*] Starting iproxy ${RAMDISK_SSH_PORT} -> 22 (UDID=${DEVICE_UDID})..."
-  ("$iproxy_bin" 2222 22 >"$IPROXY_LOG" 2>&1) &
+  ("$iproxy_bin" -u "$DEVICE_UDID" "$RAMDISK_SSH_PORT" 22 >"$IPROXY_LOG" 2>&1) &
   IPROXY_PID=$!
 
   sleep 1
@@ -431,14 +530,16 @@ wait_for_ramdisk_ssh() {
   done
 
   echo "[-] Timed out waiting for ramdisk SSH readiness."
-  echo "[-] iproxy log tail:"
+  if [[ -n "$IPROXY_LOG" ]]; then
-  tail -n 40 "$IPROXY_LOG" 2>/dev/null || true
+    echo "[-] iproxy log tail:"
+    tail -n 40 "$IPROXY_LOG" 2>/dev/null || true
+  fi
   echo "[-] boot_dfu log tail:"
   tail -n 60 "$DFU_LOG" 2>/dev/null || true
   die "Ramdisk SSH did not become ready in ${RAMDISK_SSH_TIMEOUT}s."
 }
 
-stop_iproxy_2222() {
+stop_iproxy() {
   if [[ -n "$IPROXY_PID" ]] && kill -0 "$IPROXY_PID" 2>/dev/null; then
     echo "[*] Stopping iproxy (pid=$IPROXY_PID)..."
     kill_descendants "$IPROXY_PID"
@@ -522,9 +623,10 @@ main() {
   echo ""
   echo "=== Restore phase ==="
   start_boot_dfu
+  load_device_identity
   wait_for_recovery
-  run_make "Restore" restore_get_shsh
+  run_make "Restore" restore_get_shsh RESTORE_UDID="$DEVICE_UDID" RESTORE_ECID="0x$DEVICE_ECID"
-  run_make "Restore" restore
+  run_make "Restore" restore RESTORE_UDID="$DEVICE_UDID" RESTORE_ECID="0x$DEVICE_ECID"
   wait_for_post_restore_reboot
   stop_boot_dfu
   echo "[*] Waiting ${POST_KILL_SETTLE_DELAY}s for cleanup before ramdisk stage..."
@@ -533,16 +635,17 @@ main() {
   echo ""
   echo "=== Ramdisk + CFW phase ==="
   start_boot_dfu
+  load_device_identity
   wait_for_recovery
   run_make "Ramdisk" ramdisk_build
-  run_make "Ramdisk" ramdisk_send
+  run_make "Ramdisk" ramdisk_send IRECOVERY_ECID="0x$DEVICE_ECID"
-  start_iproxy_2222
+  start_iproxy
 
   wait_for_ramdisk_ssh
 
-  run_make "CFW install" "$cfw_install_target"
+  run_make "CFW install" "$cfw_install_target" SSH_PORT="$RAMDISK_SSH_PORT"
   stop_boot_dfu
-  stop_iproxy_2222
+  stop_iproxy
 
   echo ""
   echo "=== First boot ==="

sources/vphone-cli/VPhoneControl.swift

@@ -544,7 +544,7 @@ class VPhoneControl {
         let timeoutSeconds = max(Int(timeout.rounded()), 1)
         DispatchQueue.global(qos: .utility).asyncAfter(deadline: .now() + timeout) { [weak self] in
             guard let self else { return }
-            guard let pending = self.removePending(id: id) else { return }
+            guard let pending = removePending(id: id) else { return }
             pending.handler(.failure(ControlError.requestTimedOut(type: type, seconds: timeoutSeconds)))
         }
     }

sources/vphone-cli/VPhoneFileBrowserModel.swift

@@ -195,7 +195,7 @@ class VPhoneFileBrowserModel {
         transferName = nil
         await refresh()
         // Set error after refresh so refresh() doesn't clear it before the alert fires.
-        if let e = uploadError { self.error = e }
+        if let e = uploadError { error = e }
     }
 
     func createNewFolder(name: String) async {

sources/vphone-cli/VPhoneHardwareModel.swift

@@ -13,6 +13,9 @@ import Virtualization
 /// Minimum host OS for PV=3: macOS 15.0 (Sequoia)
 ///
 enum VPhoneHardware {
+    /// Fixed CPID for the current vphone hardware descriptor.
+    static let udidChipID: UInt32 = 0xFE01
+
     static func createModel() throws -> VZMacHardwareModel {
         // platformVersion=3, boardID=0x90, ISA=2 matches vresearch101
         let desc = Dynamic._VZMacHardwareModelDescriptor()

sources/vphone-cli/VPhoneLocationProvider.swift

@@ -46,7 +46,9 @@ class VPhoneLocationProvider: NSObject {
     private var replayTask: Task<Void, Never>?
     private var replayName: String?
 
-    var isReplaying: Bool { replayTask != nil }
+    var isReplaying: Bool {
+        replayTask != nil
+    }
 
     init(control: VPhoneControl) {
         self.control = control
@@ -135,7 +137,7 @@ class VPhoneLocationProvider: NSObject {
             var index = 0
             while !Task.isCancelled {
                 let point = points[index]
-                self.sendSimulatedLocation(
+                sendSimulatedLocation(
                     latitude: point.latitude,
                     longitude: point.longitude,
                     altitude: point.altitude,

sources/vphone-cli/VPhoneVirtualMachine.swift

@@ -27,6 +27,12 @@ class VPhoneVirtualMachine: NSObject, VZVirtualMachineDelegate {
         var kernelDebugPort: Int = 5909
     }
 
+    private struct DeviceIdentity {
+        let cpidHex: String
+        let ecidHex: String
+        let udid: String
+    }
+
     init(options: Options) throws {
         // --- Hardware model (PV=3) ---
         let hwModel = try VPhoneHardware.createModel()
@@ -36,17 +42,34 @@ class VPhoneVirtualMachine: NSObject, VZVirtualMachineDelegate {
         let platform = VZMacPlatformConfiguration()
 
         // Persist machineIdentifier for stable ECID
+        let machineIdentifier: VZMacMachineIdentifier
         if let savedData = try? Data(contentsOf: options.machineIDURL),
            let savedID = VZMacMachineIdentifier(dataRepresentation: savedData)
         {
-            platform.machineIdentifier = savedID
+            machineIdentifier = savedID
             print("[vphone] Loaded machineIdentifier (ECID stable)")
         } else {
             let newID = VZMacMachineIdentifier()
-            platform.machineIdentifier = newID
+            machineIdentifier = newID
             try newID.dataRepresentation.write(to: options.machineIDURL)
             print("[vphone] Created new machineIdentifier -> \(options.machineIDURL.lastPathComponent)")
         }
+        platform.machineIdentifier = machineIdentifier
+
+        if let identity = Self.resolveDeviceIdentity(machineIdentifier: machineIdentifier) {
+            print("[vphone] ECID: 0x\(identity.ecidHex)")
+            print("[vphone] Predicted UDID: \(identity.udid)")
+            do {
+                let outputURL = try Self.writeUDIDPrediction(
+                    identity: identity, machineIDURL: options.machineIDURL
+                )
+                print("[vphone] Wrote UDID prediction: \(outputURL.path)")
+            } catch {
+                print("[vphone] Warning: failed to write udid-prediction.txt: \(error)")
+            }
+        } else {
+            print("[vphone] Warning: failed to resolve ECID from machineIdentifier")
+        }
 
         let auxStorage = try VZMacAuxiliaryStorage(
             creatingStorageAt: options.nvramURL,
@@ -204,6 +227,39 @@ class VPhoneVirtualMachine: NSObject, VZVirtualMachineDelegate {
         }
     }
 
+    private static func resolveDeviceIdentity(machineIdentifier: VZMacMachineIdentifier)
+        -> DeviceIdentity?
+    {
+        let ecidValue: UInt64? = if let ecid = Dynamic(machineIdentifier)._ECID.asUInt64 {
+            ecid
+        } else if let ecidNumber = Dynamic(machineIdentifier)._ECID.asObject as? NSNumber {
+            ecidNumber.uint64Value
+        } else {
+            nil
+        }
+
+        guard let ecidValue else { return nil }
+
+        let cpidHex = String(format: "%08X", VPhoneHardware.udidChipID)
+        let ecidHex = String(format: "%016llX", ecidValue)
+        let udid = "\(cpidHex)-\(ecidHex)"
+        return DeviceIdentity(cpidHex: cpidHex, ecidHex: ecidHex, udid: udid)
+    }
+
+    private static func writeUDIDPrediction(identity: DeviceIdentity, machineIDURL: URL) throws -> URL {
+        let outputURL = machineIDURL.deletingLastPathComponent().appendingPathComponent(
+            "udid-prediction.txt"
+        )
+        let content = """
+        UDID=\(identity.udid)
+        CPID=0x\(identity.cpidHex)
+        ECID=0x\(identity.ecidHex)
+        MACHINE_IDENTIFIER=\(machineIDURL.lastPathComponent)
+        """
+        try content.write(to: outputURL, atomically: true, encoding: .utf8)
+        return outputURL
+    }
+
     // MARK: - Battery
 
     /// Update the synthetic battery charge and connectivity at runtime.