diff --git a/z.py b/z.py
index 934b754..7c91843 100755
--- a/z.py
+++ b/z.py
@@ -10,9 +10,139 @@ import time
 from dataclasses import dataclass, field
 from typing import List, Optional
 
-# ... (imports continue)
+# Configuration variables
+default_packages = [
+    "base", "linux", "linux-firmware", "btrfs-progs", "nano", "sudo",
+    "networkmanager", "efibootmgr", "grub", "os-prober", "base-devel", "git"
+]
 
-# ... (existing code)
+@dataclass
+class InstallConfig:
+    seed_device: str
+    sprout_device: str
+    efi_device: str
+    hostname: str = "arch-z"
+    username: str = "zeev"
+    timezone: str = "Europe/Helsinki"
+    root_password: str = ""
+    user_password: str = ""
+    packages: List[str] = field(default_factory=lambda: list(default_packages))
+    dry_run: bool = False
+
+def run_command(command, check=True, shell=False, capture_output=False, dry_run=False):
+    """Result wrapper for subprocess.run"""
+    if dry_run:
+        print(f"[DRY RUN] Would execute: {command}")
+        # Return a dummy completed process for dry runs so logic doesn't crash on attribute access
+        return subprocess.CompletedProcess(args=command, returncode=0, stdout="", stderr="")
+
+    try:
+        # If command is a string and shell is False, split it (naive splitting)
+        # But better to rely on caller passing list if shell=False
+        if isinstance(command, str) and not shell:
+            cmd_list = shlex.split(command)
+        else:
+            cmd_list = command
+            
+        result = subprocess.run(
+            cmd_list,
+            check=check,
+            shell=shell,
+            text=True,
+            capture_output=capture_output
+        )
+        return result
+    except subprocess.CalledProcessError as e:
+        print(f"Error executing command: {command}")
+        print(f"Error output: {e.stderr}")
+        if check:
+            sys.exit(1)
+        return e
+
+def get_disks():
+    """Returns a list of dictionaries with disk info."""
+    cmd = ["lsblk", "-p", "-dno", "NAME,SIZE,MODEL"]
+    result = run_command(cmd, capture_output=True)
+    disks = []
+    if result.stdout:
+        lines = result.stdout.strip().split('\n')
+        for line in lines:
+            parts = line.split(maxsplit=2)
+            if len(parts) >= 2:
+                name = parts[0]
+                size = parts[1]
+                model = parts[2] if len(parts) > 2 else ""
+                disks.append({"name": name, "size": size, "model": model, "raw": line})
+    return disks
+
+def get_partitions(disk):
+    """Returns a list of partitions for the given disk."""
+    # lsblk -p -nlo NAME,SIZE,TYPE "$selected_disk" | awk '$3=="part" {printf "%s (%s)\n", $1, $2}'
+    cmd = f"lsblk -p -nlo NAME,SIZE,TYPE {disk}"
+    result = run_command(cmd, shell=True, capture_output=True)
+    parts = []
+    if result.stdout:
+        lines = result.stdout.strip().split('\n')
+        for line in lines:
+            # We want to match awk '$3=="part"' logic
+            columns = line.split()
+            if len(columns) >= 3 and columns[2] == "part":
+                # Create display string "NAME (SIZE)"
+                display = f"{columns[0]} ({columns[1]})"
+                parts.append({"path": columns[0], "display": display})
+    return parts
+
+def run_live_command(command, log_func=None, check=True, shell=False, dry_run=False):
+    """Executes a command and streams output to log_func."""
+    if dry_run:
+        if log_func:
+            log_func(f"[DRY RUN] Would execute: {command}")
+        return
+
+    # Use shell=True if command is a string, consistent with run_command logic preference
+    # though run_command defaults shell=False. We follow the caller's instructions.
+    
+    # Needs to handle list vs string same as run_command
+    if isinstance(command, str) and not shell:
+         cmd_list = shlex.split(command)
+    else:
+         cmd_list = command
+
+    process = subprocess.Popen(
+        cmd_list,
+        shell=shell,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+        text=True,
+        bufsize=1 # Line buffered
+    )
+    
+    if log_func:
+        for line in process.stdout:
+            log_func(line.rstrip())
+            
+    return_code = process.wait()
+    if check and return_code != 0:
+        if log_func:
+             log_func(f"Command failed with return code {return_code}")
+        # Mimic subprocess.CalledProcessError
+        raise subprocess.CalledProcessError(return_code, command)
+
+def check_dependencies(log_func=print):
+    """Checks if required system tools are available."""
+    required_tools = [
+        "lsblk", "btrfs", "mkfs.btrfs", "mkfs.fat", 
+        "pacstrap", "genfstab", "arch-chroot"
+    ]
+    missing = []
+    for tool in required_tools:
+        if not shutil.which(tool):
+            missing.append(tool)
+    
+    if missing:
+        msg = f"Error: Missing required tools: {', '.join(missing)}\nPlease install: btrfs-progs, dosfstools, arch-install-scripts"
+        log_func(msg)
+        raise RuntimeError(msg)
 
 def cleanup_mount(mount_point, log_func=print):
     """
@@ -48,8 +178,56 @@ def cleanup_mount(mount_point, log_func=print):
         return False
     return True
 
-# ... (perform_installation continues)
+def perform_installation(config: InstallConfig, log_func=print):
+    """
+    Executes the installation process based on the provided configuration.
+    log_func is a function to display messages (defaults to print).
+    """
+    
+    try:
+        check_dependencies(log_func)
+    except RuntimeError:
+        # If check fails, we stop. In TUI this will define the error.
+        return
 
+    # helper for dry_run propagation
+    def run(cmd, **kwargs):
+        # Merge dry_run into kwargs if not explicitly set
+        if 'dry_run' not in kwargs:
+            kwargs['dry_run'] = config.dry_run
+            
+        # If capturing output, we use the standard run_command (buffered)
+        if kwargs.get('capture_output'):
+            return run_command(cmd, **kwargs)
+        
+        # Otherwise, use live command for streaming logs
+        return run_live_command(cmd, log_func=log_func, **kwargs)
+
+    log_func("--- Starting Installation ---")
+    
+    # Get Sprout PARTUUID
+    if config.dry_run:
+        sprout_partuuid = "DRY-RUN-UUID-1234"
+    else:
+        cmd_uuid = f"blkid -s PARTUUID -o value {config.sprout_device}"
+        sprout_partuuid = run(cmd_uuid, shell=True, capture_output=True).stdout.strip()
+    
+    log_func(f"Sprout PARTUUID: {sprout_partuuid}")
+    
+    # Check mountpoint
+    # For dry_run we might want to skip real checks or mock them
+    if not config.dry_run:
+        mount_check = subprocess.run(["mountpoint", "-q", "/mnt"], check=False)
+        if mount_check.returncode == 0:
+            log_func("/mnt is already mounted. Unmounting...")
+            cleanup_mount("/mnt", log_func)
+
+    log_func("Creating filesystems...")
+    run(f"mkfs.btrfs -f -L SEED {config.seed_device}", shell=True)
+    run(f"mkfs.btrfs -f -L SPROUT {config.sprout_device}", shell=True)
+    run(f"mkfs.fat -F 32 -n EFI {config.efi_device}", shell=True)
+    log_func("Filesystems created successfully.")
+        
     # Initial Mount
     run(f"mount -o subvol=/ {config.seed_device} /mnt", shell=True)
     
@@ -63,7 +241,43 @@ def cleanup_mount(mount_point, log_func=print):
     cleanup_mount("/mnt", log_func)
     run(f"mount -o subvol=/@ {config.seed_device} /mnt", shell=True)
     
-    # ... (skipping to end of chroot)
+    # Pacstrap
+    log_func(f"Installing packages: {' '.join(config.packages)}")
+    run(["pacstrap", "-K", "/mnt"] + config.packages)
+    run(f"mount -m {config.efi_device} /mnt/efi", shell=True)
+    
+    # fstab
+    if not config.dry_run:
+        with open("/mnt/etc/fstab", "w") as f:
+            subprocess.run(["genfstab", "-U", "/mnt"], stdout=f, check=True)
+    else:
+        log_func("[DRY RUN] Would generate fstab")
+        
+    # Chroot function
+    mkinitcpio_hooks = "base udev autodetect microcode modconf kms keyboard block btrfs filesystems"
+    grub_options = "--target=x86_64-efi --efi-directory=/efi --boot-directory=/boot --bootloader-id=GRUB"
+    
+    install_script = [
+        "hwclock --systohc",
+        f"echo '{config.hostname}' > /etc/hostname",
+        "echo 'KEYMAP=us' > /etc/vconsole.conf",
+        "sed -i 's/^#en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen",
+        "locale-gen",
+        "echo 'LANG=en_US.UTF-8' > /etc/locale.conf",
+        f"ln -sf /usr/share/zoneinfo/{config.timezone} /etc/localtime",
+        f'sed -i "s/^HOOKS=.*/HOOKS=({mkinitcpio_hooks})/" /etc/mkinitcpio.conf',
+        f"echo 'root:{config.root_password}' | chpasswd",
+        f"useradd -m -G wheel -s /usr/bin/bash {config.username}",
+        f"echo '{config.username}:{config.user_password}' | chpasswd",
+        f"echo '{config.username} ALL=(ALL:ALL) ALL' > /etc/sudoers.d/{config.username}",
+        "systemctl enable systemd-timesyncd",
+        f"grub-install {grub_options}",
+        "echo 'GRUB_DISABLE_OS_PROBER=false' >> /etc/default/grub",
+        "grub-mkconfig -o /boot/grub/grub.cfg",
+        f"sed -i 's/root=UUID=[A-Fa-f0-9-]*/root=PARTUUID={sprout_partuuid}/g' /boot/grub/grub.cfg",
+        "passwd -l root",
+        "mkinitcpio -P"
+    ]
     
     full_script = "\n".join(install_script)
     # arch-chroot /mnt /usr/bin/bash -c "$cmd"