feat: Implement dataset versioning and management for NNUE training data

modules/bot/python/.gitignore

@@ -19,3 +19,4 @@ ENV/
 *.swo
 tactical_data/
 trainingdata/
+/datasets/

modules/bot/python/DATASETS.md

@@ -0,0 +1,173 @@
+# Training Dataset Management
+
+The NNUE training pipeline now features versioned dataset management, similar to model versioning. This prevents data loss and allows you to maintain multiple training configurations.
+
+## Directory Structure
+
+```
+datasets/
+  ds_v1/
+    labeled.jsonl       # Training data: {"fen": "...", "eval": 0.5, "eval_raw": 150}
+    metadata.json       # Version info and composition
+  ds_v2/
+    labeled.jsonl
+    metadata.json
+```
+
+## Metadata Schema
+
+Each dataset has a `metadata.json` file tracking its composition:
+
+```json
+{
+  "version": 1,
+  "created": "2026-04-13T15:30:45.123456",
+  "total_positions": 1000000,
+  "stockfish_depth": 12,
+  "sources": [
+    {
+      "type": "generated",
+      "count": 500000,
+      "params": {
+        "num_positions": 500000,
+        "min_move": 1,
+        "max_move": 50
+      }
+    },
+    {
+      "type": "tactical",
+      "count": 300000,
+      "max_puzzles": 300000
+    },
+    {
+      "type": "file_import",
+      "count": 200000,
+      "path": "/path/to/original_file.txt"
+    }
+  ]
+}
+```
+
+## TUI Workflow
+
+### Main Menu
+```
+1 - Manage Training Data
+2 - Train Model
+3 - Export Model
+4 - Exit
+```
+
+### Training Data Management Submenu
+```
+1 - Create new dataset
+2 - Extend existing dataset
+3 - View all datasets
+4 - Delete dataset
+5 - Back
+```
+
+## Creating a Dataset
+
+Use the "Create new dataset" option to add data from one or more sources:
+
+1. **Generate random positions** — Play random games and sample positions
+   - Number of positions
+   - Move range (min/max move number to sample from)
+   - Number of worker threads
+
+2. **Import from file** — Load positions from a FEN file
+   - File must contain one FEN string per line
+   - Duplicates are automatically removed
+
+3. **Extract tactical puzzles** — Download and extract Lichess puzzle database
+   - Maximum number of puzzles to include
+   - Automatically filters for tactical themes (forks, pins, mates, etc.)
+
+You can combine multiple sources in a single dataset creation session. All positions are:
+- Deduplicated (only unique FENs are kept)
+- Labeled with Stockfish evaluations
+- Saved to `datasets/ds_vN/labeled.jsonl`
+
+## Extending a Dataset
+
+Use "Extend existing dataset" to add more positions to an existing dataset:
+
+1. Select the dataset version to extend
+2. Choose data sources (same options as creation)
+3. Confirm labeling parameters
+4. New positions are:
+   - Labeled with Stockfish
+   - Deduplicated against the target dataset (preventing duplicates)
+   - Merged into the existing `labeled.jsonl`
+   - Metadata is updated with the new source entry
+
+## Training with a Dataset
+
+When you start training (Standard or Burst mode), you'll be prompted to select a dataset version. The TUI will display all available datasets with:
+- Version number
+- Total number of positions
+- Source types (generated, tactical, imported)
+- Stockfish depth used
+- Creation date
+
+## Legacy Data Migration
+
+If you have existing labeled data in `data/training_data.jsonl` from before this update:
+
+1. Open the "Manage Training Data" menu
+2. Choose "Create new dataset"
+3. Select "Import from file"
+4. Point to `data/training_data.jsonl`
+5. Complete the dataset creation
+
+Alternatively, you can manually copy the file to `datasets/ds_v1/labeled.jsonl` and create a `metadata.json` file.
+
+## Viewing Dataset Details
+
+Use "View all datasets" to see a table of all datasets with:
+- Version number
+- Position count
+- Source composition
+- Stockfish depth
+- Creation date
+
+## Deleting a Dataset
+
+Use "Delete dataset" to remove a dataset and free up disk space. **This action cannot be undone.**
+
+⚠️ The system does not prevent deleting datasets used by model checkpoints. Plan accordingly.
+
+## Technical Details
+
+### Deduplication Strategy
+
+When extending a dataset, positions are deduplicated **within that dataset only**. This allows different datasets to contain overlapping positions if desired.
+
+When creating a new dataset from multiple sources, all sources are combined and deduplicated before labeling.
+
+### Labeled Position Format
+
+Each line in `labeled.jsonl` is a JSON object:
+```json
+{
+  "fen": "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
+  "eval": 0.0,
+  "eval_raw": 0
+}
+```
+
+- `fen`: The position in Forsyth-Edwards Notation
+- `eval`: Normalized evaluation ([-1, 1] range using tanh)
+- `eval_raw`: Raw Stockfish evaluation in centipawns
+
+### Storage Location
+
+Datasets are stored in the `datasets/` directory relative to the script location. The old `data/` directory is preserved for backward compatibility but is not actively used by the new system.
+
+## Performance Tips
+
+- **Smaller datasets train faster** — Start with 100k-500k positions
+- **Deduplication matters** — Use the extend functionality to build up your dataset without redundant data
+- **Stockfish depth** — Depth 12-14 balances accuracy and labeling speed
+- **Workers** — Use 4-8 workers for labeling if your machine supports it; more workers = faster but uses more CPU/memory

modules/bot/python/nnue.py

@@ -4,6 +4,7 @@
 import os
 import shutil
 import sys
+import tempfile
 from pathlib import Path
 from rich.console import Console
 from rich.table import Table
@@ -17,23 +18,23 @@ sys.path.insert(0, str(Path(__file__).parent / "src"))
 from generate import play_random_game_and_collect_positions
 from label import label_positions_with_stockfish
 from train import train_nnue, burst_train
-from export import export_weights_to_binary
+from export import export_to_nbai
 from tactical_positions_extractor import (
     download_and_extract_puzzle_db,
-    interactive_merge_positions
+    extract_tactical_only
+)
+from dataset import (
+    get_datasets_dir,
+    list_datasets,
+    next_dataset_version,
+    load_dataset_metadata,
+    create_dataset,
+    extend_dataset,
+    get_dataset_labeled_path,
+    delete_dataset,
+    show_datasets_table
 )
 
-def get_data_dir():
-    """Get/create data directory."""
-    data_dir = Path(__file__).parent / "data"
-    data_dir.mkdir(exist_ok=True)
-    return data_dir
-
-def get_tactical_data_dir():
-    """Get/create data directory."""
-    data_dir = Path(__file__).parent / "tactical_data"
-    data_dir.mkdir(exist_ok=True)
-    return data_dir
 
 def get_weights_dir():
     """Get/create weights directory."""
@@ -41,6 +42,14 @@ def get_weights_dir():
     weights_dir.mkdir(exist_ok=True)
     return weights_dir
 
+
+def get_data_dir():
+    """Get/create legacy data directory (for migration)."""
+    data_dir = Path(__file__).parent / "data"
+    data_dir.mkdir(exist_ok=True)
+    return data_dir
+
+
 def list_checkpoints():
     """List available checkpoint versions."""
     weights_dir = get_weights_dir()
@@ -49,6 +58,20 @@ def list_checkpoints():
         return []
     return [int(cp.stem.split("_v")[1]) for cp in checkpoints]
 
+
+def migrate_legacy_data():
+    """On first run, offer to import existing data/training_data.jsonl as ds_v1."""
+    console = Console()
+    data_dir = get_data_dir()
+    legacy_file = data_dir / "training_data.jsonl"
+    datasets = list_datasets()
+
+    # Only migrate if legacy data exists and no datasets exist yet
+    if legacy_file.exists() and not datasets:
+        console.print("\n[cyan]Legacy data detected: data/training_data.jsonl[/cyan]")
+        console.print("[dim]Tip: Use 'Manage Training Data' menu to import it as ds_v1[/dim]")
+
+
 def show_header():
     """Display application header."""
     console = Console()
@@ -56,22 +79,23 @@ def show_header():
     console.print(
         Panel(
             "[bold cyan]🧠 NNUE Training Pipeline[/bold cyan]\n"
-            "[dim]Neural Network Utility Evaluation - Model Management[/dim]",
+            "[dim]Neural Network Utility Evaluation - Dataset & Model Management[/dim]",
             border_style="cyan",
             padding=(1, 2),
         )
     )
 
+
 def show_checkpoints_table():
     """Display available checkpoints in a table."""
     console = Console()
     available = list_checkpoints()
 
     if not available:
-        console.print("[yellow]ℹ No checkpoints found yet[/yellow]")
+        console.print("[yellow]ℹ No model checkpoints found yet[/yellow]")
         return
 
-    table = Table(title="Available Checkpoints", show_header=True, header_style="bold cyan")
+    table = Table(title="Available Model Checkpoints", show_header=True, header_style="bold cyan")
     table.add_column("Version", style="dim")
     table.add_column("File Size", justify="right")
     table.add_column("Status", justify="center")
@@ -87,46 +111,500 @@ def show_checkpoints_table():
 
     console.print(table)
 
+
 def show_main_menu():
     """Display and handle main menu."""
     console = Console()
 
+    # Migrate legacy data on first run
+    migrate_legacy_data()
+
     while True:
         show_header()
         show_checkpoints_table()
 
         console.print("\n[bold]What would you like to do?[/bold]")
-        console.print("[cyan]1[/cyan] - Train NNUE Model")
-        console.print("[cyan]2[/cyan] - Burst Train NNUE Model")
-        console.print("[cyan]3[/cyan] - Export Weights to Scala")
-        console.print("[cyan]4[/cyan] - Extract Tactical Positions")
-        console.print("[cyan]5[/cyan] - View Checkpoints")
-        console.print("[cyan]6[/cyan] - Exit")
+        console.print("[cyan]1[/cyan] - Manage Training Data")
+        console.print("[cyan]2[/cyan] - Train Model")
+        console.print("[cyan]3[/cyan] - Export Model")
+        console.print("[cyan]4[/cyan] - Exit")
 
-        choice = Prompt.ask("\nSelect option", choices=["1", "2", "3", "4", "5", "6"])
+        choice = Prompt.ask("\nSelect option", choices=["1", "2", "3", "4"])
+
+        if choice == "1":
+            datasets_menu()
+        elif choice == "2":
+            training_menu()
+        elif choice == "3":
+            export_interactive()
+        elif choice == "4":
+            console.print("[yellow]👋 Goodbye![/yellow]")
+            return
+
+
+def datasets_menu():
+    """Dataset management submenu."""
+    console = Console()
+
+    while True:
+        show_header()
+        show_datasets_table(console)
+
+        console.print("\n[bold]Training Data Management[/bold]")
+        console.print("[cyan]1[/cyan] - Create new dataset")
+        console.print("[cyan]2[/cyan] - Extend existing dataset")
+        console.print("[cyan]3[/cyan] - View all datasets")
+        console.print("[cyan]4[/cyan] - Delete dataset")
+        console.print("[cyan]5[/cyan] - Back")
+
+        choice = Prompt.ask("\nSelect option", choices=["1", "2", "3", "4", "5"])
+
+        if choice == "1":
+            create_dataset_interactive()
+        elif choice == "2":
+            extend_dataset_interactive()
+        elif choice == "3":
+            show_header()
+            show_datasets_table(console)
+            Prompt.ask("\nPress Enter to continue")
+        elif choice == "4":
+            delete_dataset_interactive()
+        elif choice == "5":
+            return
+
+
+def create_dataset_interactive():
+    """Interactive dataset creation flow."""
+    console = Console()
+    show_header()
+
+    console.print("\n[bold cyan]📊 Create New Dataset[/bold cyan]")
+
+    sources = []
+    combined_count = 0
+
+    # Allow user to add multiple sources
+    while True:
+        console.print("\n[bold]Add data source (repeat until done):[/bold]")
+        console.print("[cyan]a[/cyan] - Generate random positions")
+        console.print("[cyan]b[/cyan] - Import from file")
+        console.print("[cyan]c[/cyan] - Extract Lichess tactical puzzles")
+        console.print("[cyan]d[/cyan] - Done adding sources")
+
+        choice = Prompt.ask("Select", choices=["a", "b", "c", "d"])
+
+        if choice == "a":
+            num_positions = int(Prompt.ask("Number of positions to generate", default="100000"))
+            min_move = int(Prompt.ask("Minimum move number", default="1"))
+            max_move = int(Prompt.ask("Maximum move number", default="50"))
+            num_workers = int(Prompt.ask("Number of workers", default="8"))
+
+            console.print("[dim]Generating positions...[/dim]")
+            temp_file = Path(tempfile.gettempdir()) / "temp_positions.txt"
+            count = play_random_game_and_collect_positions(
+                str(temp_file),
+                total_positions=num_positions,
+                samples_per_game=1,
+                min_move=min_move,
+                max_move=max_move,
+                num_workers=num_workers
+            )
+            if count > 0:
+                sources.append({
+                    "type": "generated",
+                    "count": count,
+                    "params": {"num_positions": num_positions, "min_move": min_move, "max_move": max_move}
+                })
+                combined_count += count
+                console.print(f"[green]✓ {count:,} positions generated[/green]")
+            else:
+                console.print("[red]✗ Generation failed[/red]")
+
+        elif choice == "b":
+            file_path = Prompt.ask("Path to FEN file")
+            try:
+                with open(file_path, 'r') as f:
+                    count = sum(1 for _ in f)
+                sources.append({"type": "file_import", "count": count, "path": file_path})
+                combined_count += count
+                console.print(f"[green]✓ {count:,} positions from file[/green]")
+            except FileNotFoundError:
+                console.print(f"[red]✗ File not found: {file_path}[/red]")
+
+        elif choice == "c":
+            max_puzzles = int(Prompt.ask("Maximum puzzles to extract", default="300000"))
+            console.print("[dim]Extracting tactical positions...[/dim]")
+            temp_file = Path(tempfile.gettempdir()) / "temp_tactical.txt"
+            try:
+                csv_path = download_and_extract_puzzle_db(output_dir=str(Path(__file__).parent / "tactical_data"))
+                if csv_path:
+                    count = extract_tactical_only(csv_path, str(temp_file), max_puzzles)
+                    sources.append({"type": "tactical", "count": count, "max_puzzles": max_puzzles})
+                    combined_count += count
+                    console.print(f"[green]✓ {count:,} tactical positions extracted[/green]")
+            except Exception as e:
+                console.print(f"[red]✗ Tactical extraction failed: {e}[/red]")
+
+        elif choice == "d":
+            if not sources:
+                console.print("[yellow]⚠ No sources added yet[/yellow]")
+                continue
+            break
+
+    if not sources:
+        console.print("[yellow]Dataset creation cancelled[/yellow]")
+        return
+
+    # Stockfish labeling parameters
+    console.print("\n[bold cyan]🏷️  Labeling Parameters[/bold cyan]")
+    stockfish_path = Prompt.ask(
+        "Stockfish path",
+        default=os.environ.get("STOCKFISH_PATH") or shutil.which("stockfish") or "/usr/bin/stockfish"
+    )
+    stockfish_depth = int(Prompt.ask("Stockfish analysis depth", default="12"))
+    num_workers = int(Prompt.ask("Number of parallel workers", default="1"))
+
+    # Summary and confirm
+    console.print("\n[bold]Dataset Summary:[/bold]")
+    console.print(f"  Total positions: {combined_count:,}")
+    for source in sources:
+        console.print(f"  - {source['type']}: {source['count']:,}")
+    console.print(f"  Stockfish depth: {stockfish_depth}")
+
+    if not Confirm.ask("\nProceed to label and create dataset?", default=True):
+        console.print("[yellow]Cancelled[/yellow]")
+        return
+
+    try:
+        # Combine all sources into one FEN file
+        console.print("\n[bold cyan]Step 1: Combining sources[/bold cyan]")
+        combined_fen_file = Path(tempfile.gettempdir()) / "combined_positions.txt"
+        all_fens = set()
+
+        for source in sources:
+            if source['type'] == 'generated':
+                temp_file = Path(tempfile.gettempdir()) / "temp_positions.txt"
+            elif source['type'] == 'file_import':
+                temp_file = Path(source['path'])
+            elif source['type'] == 'tactical':
+                temp_file = Path(tempfile.gettempdir()) / "temp_tactical.txt"
+
+            if temp_file.exists():
+                with open(temp_file, 'r') as f:
+                    for line in f:
+                        fen = line.strip()
+                        if fen:
+                            all_fens.add(fen)
+
+        with open(combined_fen_file, 'w') as f:
+            for fen in all_fens:
+                f.write(fen + '\n')
+        console.print(f"[green]✓ Combined {len(all_fens):,} unique positions[/green]")
+
+        # Label positions
+        console.print("\n[bold cyan]Step 2: Labeling Positions[/bold cyan]")
+        labeled_file = Path(tempfile.gettempdir()) / "labeled.jsonl"
+        success = label_positions_with_stockfish(
+            str(combined_fen_file),
+            str(labeled_file),
+            stockfish_path,
+            depth=stockfish_depth,
+            num_workers=num_workers
+        )
+
+        if not success:
+            console.print("[red]✗ Labeling failed[/red]")
+            return
+
+        console.print("[green]✓ Positions labeled[/green]")
+
+        # Save dataset
+        console.print("\n[bold cyan]Step 3: Creating Dataset[/bold cyan]")
+        version = next_dataset_version()
+        create_dataset(
+            version=version,
+            labeled_jsonl_path=str(labeled_file),
+            sources=sources,
+            stockfish_depth=stockfish_depth
+        )
+        console.print(f"[green]✓ Dataset created: ds_v{version}[/green]")
+        console.print(f"[bold]Location: {get_datasets_dir() / f'ds_v{version}'}[/bold]")
+
+        Prompt.ask("\nPress Enter to continue")
+
+    except Exception as e:
+        console.print(f"[red]✗ Error: {e}[/red]")
+        import traceback
+        traceback.print_exc()
+        Prompt.ask("Press Enter to continue")
+
+
+def extend_dataset_interactive():
+    """Interactive dataset extension flow."""
+    console = Console()
+    show_header()
+
+    console.print("\n[bold cyan]📊 Extend Existing Dataset[/bold cyan]")
+
+    datasets = list_datasets()
+    if not datasets:
+        console.print("[yellow]ℹ No datasets available to extend[/yellow]")
+        Prompt.ask("Press Enter to continue")
+        return
+
+    show_datasets_table(console)
+    version = int(Prompt.ask("\nEnter dataset version to extend (e.g., 1)"))
+
+    if not any(v == version for v, _ in datasets):
+        console.print("[red]✗ Dataset not found[/red]")
+        return
+
+    sources = []
+    combined_count = 0
+
+    # Allow user to add sources
+    while True:
+        console.print("\n[bold]Add data source:[/bold]")
+        console.print("[cyan]a[/cyan] - Generate random positions")
+        console.print("[cyan]b[/cyan] - Import from file")
+        console.print("[cyan]c[/cyan] - Extract Lichess tactical puzzles")
+        console.print("[cyan]d[/cyan] - Done adding sources")
+
+        choice = Prompt.ask("Select", choices=["a", "b", "c", "d"])
+
+        if choice == "a":
+            num_positions = int(Prompt.ask("Number of positions to generate", default="100000"))
+            min_move = int(Prompt.ask("Minimum move number", default="1"))
+            max_move = int(Prompt.ask("Maximum move number", default="50"))
+            num_workers = int(Prompt.ask("Number of workers", default="8"))
+
+            console.print("[dim]Generating positions...[/dim]")
+            temp_file = Path(tempfile.gettempdir()) / "temp_positions.txt"
+            count = play_random_game_and_collect_positions(
+                str(temp_file),
+                total_positions=num_positions,
+                samples_per_game=1,
+                min_move=min_move,
+                max_move=max_move,
+                num_workers=num_workers
+            )
+            if count > 0:
+                sources.append({
+                    "type": "generated",
+                    "count": count,
+                    "params": {"num_positions": num_positions, "min_move": min_move, "max_move": max_move}
+                })
+                combined_count += count
+                console.print(f"[green]✓ {count:,} positions generated[/green]")
+
+        elif choice == "b":
+            file_path = Prompt.ask("Path to FEN file")
+            try:
+                with open(file_path, 'r') as f:
+                    count = sum(1 for _ in f)
+                sources.append({"type": "file_import", "count": count, "path": file_path})
+                combined_count += count
+                console.print(f"[green]✓ {count:,} positions from file[/green]")
+            except FileNotFoundError:
+                console.print(f"[red]✗ File not found: {file_path}[/red]")
+
+        elif choice == "c":
+            max_puzzles = int(Prompt.ask("Maximum puzzles to extract", default="300000"))
+            console.print("[dim]Extracting tactical positions...[/dim]")
+            temp_file = Path(tempfile.gettempdir()) / "temp_tactical.txt"
+            try:
+                csv_path = download_and_extract_puzzle_db(output_dir=str(Path(__file__).parent / "tactical_data"))
+                if csv_path:
+                    count = extract_tactical_only(csv_path, str(temp_file), max_puzzles)
+                    sources.append({"type": "tactical", "count": count, "max_puzzles": max_puzzles})
+                    combined_count += count
+                    console.print(f"[green]✓ {count:,} tactical positions extracted[/green]")
+            except Exception as e:
+                console.print(f"[red]✗ Extraction failed: {e}[/red]")
+
+        elif choice == "d":
+            if not sources:
+                console.print("[yellow]⚠ No sources added yet[/yellow]")
+                continue
+            break
+
+    if not sources:
+        console.print("[yellow]Extension cancelled[/yellow]")
+        return
+
+    # Stockfish labeling parameters
+    console.print("\n[bold cyan]🏷️  Labeling Parameters[/bold cyan]")
+    stockfish_path = Prompt.ask(
+        "Stockfish path",
+        default=os.environ.get("STOCKFISH_PATH") or shutil.which("stockfish") or "/usr/bin/stockfish"
+    )
+    stockfish_depth = int(Prompt.ask("Stockfish analysis depth", default="12"))
+    num_workers = int(Prompt.ask("Number of parallel workers", default="1"))
+
+    # Summary and confirm
+    console.print("\n[bold]Extension Summary:[/bold]")
+    console.print(f"  Target dataset: ds_v{version}")
+    console.print(f"  New positions: {combined_count:,}")
+    for source in sources:
+        console.print(f"  - {source['type']}: {source['count']:,}")
+
+    if not Confirm.ask("\nProceed to label and extend dataset?", default=True):
+        console.print("[yellow]Cancelled[/yellow]")
+        return
+
+    try:
+        # Combine all sources into one FEN file
+        console.print("\n[bold cyan]Step 1: Combining sources[/bold cyan]")
+        combined_fen_file = Path(tempfile.gettempdir()) / "combined_positions.txt"
+        all_fens = set()
+
+        for source in sources:
+            if source['type'] == 'generated':
+                temp_file = Path(tempfile.gettempdir()) / "temp_positions.txt"
+            elif source['type'] == 'file_import':
+                temp_file = Path(source['path'])
+            elif source['type'] == 'tactical':
+                temp_file = Path(tempfile.gettempdir()) / "temp_tactical.txt"
+
+            if temp_file.exists():
+                with open(temp_file, 'r') as f:
+                    for line in f:
+                        fen = line.strip()
+                        if fen:
+                            all_fens.add(fen)
+
+        with open(combined_fen_file, 'w') as f:
+            for fen in all_fens:
+                f.write(fen + '\n')
+        console.print(f"[green]✓ Combined {len(all_fens):,} unique positions[/green]")
+
+        # Label positions
+        console.print("\n[bold cyan]Step 2: Labeling Positions[/bold cyan]")
+        labeled_file = Path(tempfile.gettempdir()) / "labeled.jsonl"
+        success = label_positions_with_stockfish(
+            str(combined_fen_file),
+            str(labeled_file),
+            stockfish_path,
+            depth=stockfish_depth,
+            num_workers=num_workers
+        )
+
+        if not success:
+            console.print("[red]✗ Labeling failed[/red]")
+            return
+
+        console.print("[green]✓ Positions labeled[/green]")
+
+        # Extend dataset
+        console.print("\n[bold cyan]Step 3: Extending Dataset[/bold cyan]")
+        success = extend_dataset(
+            version=version,
+            new_labeled_path=str(labeled_file),
+            new_source_entry={
+                "type": "merged_sources",
+                "count": len(all_fens),
+                "sources": sources
+            }
+        )
+
+        if success:
+            metadata = load_dataset_metadata(version)
+            console.print(f"[green]✓ Dataset extended[/green]")
+            console.print(f"[bold]Total positions: {metadata['total_positions']:,}[/bold]")
+        else:
+            console.print("[red]✗ Extension failed[/red]")
+
+        Prompt.ask("\nPress Enter to continue")
+
+    except Exception as e:
+        console.print(f"[red]✗ Error: {e}[/red]")
+        import traceback
+        traceback.print_exc()
+        Prompt.ask("Press Enter to continue")
+
+
+def delete_dataset_interactive():
+    """Interactive dataset deletion."""
+    console = Console()
+    show_header()
+
+    console.print("\n[bold cyan]⚠️  Delete Dataset[/bold cyan]")
+
+    datasets = list_datasets()
+    if not datasets:
+        console.print("[yellow]ℹ No datasets to delete[/yellow]")
+        Prompt.ask("Press Enter to continue")
+        return
+
+    show_datasets_table(console)
+    version = int(Prompt.ask("\nEnter dataset version to delete (e.g., 1)"))
+
+    if not any(v == version for v, _ in datasets):
+        console.print("[red]✗ Dataset not found[/red]")
+        return
+
+    if Confirm.ask(f"Delete ds_v{version}? This cannot be undone.", default=False):
+        if delete_dataset(version):
+            console.print(f"[green]✓ Dataset ds_v{version} deleted[/green]")
+        else:
+            console.print("[red]✗ Deletion failed[/red]")
+
+    Prompt.ask("Press Enter to continue")
+
+
+def training_menu():
+    """Training submenu."""
+    console = Console()
+
+    while True:
+        show_header()
+
+        console.print("\n[bold]Training[/bold]")
+        console.print("[cyan]1[/cyan] - Standard Training")
+        console.print("[cyan]2[/cyan] - Burst Training")
+        console.print("[cyan]3[/cyan] - View Model Checkpoints")
+        console.print("[cyan]4[/cyan] - Back")
+
+        choice = Prompt.ask("\nSelect option", choices=["1", "2", "3", "4"])
 
         if choice == "1":
             train_interactive()
         elif choice == "2":
             burst_train_interactive()
         elif choice == "3":
-            export_interactive()
-        elif choice == "4":
-            extract_tactical_interactive()
-        elif choice == "5":
             show_header()
             show_checkpoints_table()
             Prompt.ask("\nPress Enter to continue")
-        elif choice == "6":
-            console.print("[yellow]👋 Goodbye![/yellow]")
+        elif choice == "4":
             return
 
+
 def train_interactive():
     """Interactive training menu."""
     console = Console()
     show_header()
 
-    console.print("\n[bold cyan]📚 Training Configuration[/bold cyan]")
+    console.print("\n[bold cyan]📚 Standard Training Configuration[/bold cyan]")
+
+    # Dataset selection
+    datasets = list_datasets()
+    if not datasets:
+        console.print("[red]✗ No datasets available. Create one first.[/red]")
+        Prompt.ask("Press Enter to continue")
+        return
+
+    console.print("\n[bold]Available Datasets:[/bold]")
+    show_datasets_table(console)
+    dataset_version = int(Prompt.ask("\nEnter dataset version to train on (e.g., 1)"))
+
+    if not any(v == dataset_version for v, _ in datasets):
+        console.print("[red]✗ Dataset not found[/red]")
+        return
+
+    labeled_file = get_dataset_labeled_path(dataset_version)
+    if not labeled_file:
+        console.print("[red]✗ Dataset labeled.jsonl not found[/red]")
+        return
 
     # Checkpoint selection
     available = list_checkpoints()
@@ -142,36 +620,6 @@ def train_interactive():
                 default=str(max(available))
             )
 
-    # Positions source
-    use_existing = Confirm.ask("Use existing positions file?", default=False)
-    positions_file = None
-    num_games = 500000
-    samples_per_game = 1
-    min_move = 1
-    max_move = 50
-
-    if use_existing:
-        positions_file = Prompt.ask("Enter path to positions file", default=str(get_data_dir() / "positions.txt"))
-    else:
-        num_games = int(Prompt.ask("Number of games to generate", default="5000"))
-        samples_per_game = int(Prompt.ask("Positions to sample per game", default="1"))
-        min_move = int(Prompt.ask("Minimum move number", default="1"))
-        max_move = int(Prompt.ask("Maximum move number", default="50"))
-
-    use_existing_labels = Confirm.ask("Use existing labels file?", default=False)
-    labels_file = None
-    if use_existing_labels:
-        labels_file = Prompt.ask("Enter path to labels file", default=str(get_data_dir() / "training_data.jsonl"))
-
-    # Stockfish path and labeling parameters
-    default_stockfish = os.environ.get("STOCKFISH_PATH") or shutil.which("stockfish") or "/usr/bin/stockfish"
-    stockfish_path = Prompt.ask("Stockfish path", default=default_stockfish)
-    stockfish_depth = 12
-    num_workers = 1
-    if not use_existing_labels:
-        stockfish_depth = int(Prompt.ask("Stockfish analysis depth", default="12"))
-        num_workers = int(Prompt.ask("Number of parallel workers", default="1"))
-
     # Training parameters
     epochs = int(Prompt.ask("Number of epochs", default="100"))
     batch_size = int(Prompt.ask("Batch size", default="16384"))
@@ -182,16 +630,7 @@ def train_interactive():
 
     # Confirm and start
     console.print("\n[bold]Configuration Summary:[/bold]")
-    if use_checkpoint:
-        console.print(f"  Checkpoint: v{checkpoint_version}")
-    else:
-        console.print("  Checkpoint: None (training from scratch)")
-    if not use_existing:
-        console.print(f"  Games: {num_games:,}")
-        console.print(f"  Samples per game: {samples_per_game}")
-        console.print(f"  Move range: {min_move}-{max_move}")
-    else:
-        console.print(f"  Positions file: {positions_file}")
+    console.print(f"  Dataset: ds_v{dataset_version}")
     console.print(f"  Epochs: {epochs}")
     console.print(f"  Batch size: {batch_size}")
     console.print(f"  Subsample ratio: {subsample_ratio:.0%}")
@@ -199,70 +638,27 @@ def train_interactive():
         console.print(f"  Early stopping: Yes (patience: {early_stopping})")
     else:
         console.print(f"  Early stopping: No")
-    if not use_existing_labels:
-        console.print(f"  Stockfish depth: {stockfish_depth}")
-        console.print(f"  Workers: {num_workers}")
-    console.print(f"  Stockfish: {stockfish_path}")
+    if use_checkpoint:
+        console.print(f"  Checkpoint: v{checkpoint_version}")
+    else:
+        console.print(f"  Checkpoint: None (training from scratch)")
 
     if not Confirm.ask("\nStart training?", default=True):
         console.print("[yellow]Training cancelled[/yellow]")
+        Prompt.ask("Press Enter to continue")
         return
 
     # Execute training
-    data_dir = get_data_dir()
     weights_dir = get_weights_dir()
 
     try:
-        # Generate positions
-        if not use_existing:
-            console.print("\n[bold cyan]Step 1: Generating Positions[/bold cyan]")
-            count = play_random_game_and_collect_positions(
-                str(data_dir / "positions.txt"),
-                total_games=num_games,
-                samples_per_game=samples_per_game,
-                min_move=min_move,
-                max_move=max_move
-            )
-            if count == 0:
-                console.print("[red]✗ No valid positions generated[/red]")
-                return
-            console.print(f"[green]✓ Generated {count:,} positions[/green]")
-        else:
-            if not Path(positions_file).exists():
-                console.print(f"[red]✗ Positions file not found: {positions_file}[/red]")
-                return
-
-        if not use_existing_labels:
-            # Label positions
-            console.print("\n[bold cyan]Step 2: Labeling Positions[/bold cyan]")
-            positions_file = data_dir / "positions.txt"
-            output_file = data_dir / "training_data.jsonl"
-            success = label_positions_with_stockfish(
-                str(positions_file),
-                str(output_file),
-                stockfish_path,
-                depth=stockfish_depth,
-                num_workers=num_workers
-            )
-            if not success:
-                console.print("[red]✗ Position labeling failed[/red]")
-                return
-            console.print(f"[green]✓ Positions labeled[/green]")
-        else:
-            console.print("\n[bold cyan]Step 2: Loading Existing Labels[/bold cyan]")
-            output_file = labels_file
-            if not Path(output_file).exists():
-                console.print(f"[red]✗ Labels file not found: {output_file}[/red]")
-                return
-
-        # Train model
-        console.print("\n[bold cyan]Step 3: Training Model[/bold cyan]")
+        console.print("\n[bold cyan]Training Model[/bold cyan]")
         checkpoint = None
         if use_checkpoint:
             checkpoint = str(weights_dir / f"nnue_weights_v{checkpoint_version}.pt")
 
         train_nnue(
-            data_file=str(output_file),
+            data_file=str(labeled_file),
             output_file=str(weights_dir / "nnue_weights.pt"),
             epochs=epochs,
             batch_size=batch_size,
@@ -286,6 +682,7 @@ def train_interactive():
         traceback.print_exc()
         Prompt.ask("Press Enter to continue")
 
+
 def burst_train_interactive():
     """Interactive burst training menu."""
     console = Console()
@@ -294,14 +691,30 @@ def burst_train_interactive():
     console.print("\n[bold cyan]⚡ Burst Training Configuration[/bold cyan]")
     console.print("[dim]Repeatedly restarts from the best checkpoint until the time budget expires.[/dim]\n")
 
+    # Dataset selection
+    datasets = list_datasets()
+    if not datasets:
+        console.print("[red]✗ No datasets available. Create one first.[/red]")
+        Prompt.ask("Press Enter to continue")
+        return
+
+    console.print("[bold]Available Datasets:[/bold]")
+    show_datasets_table(console)
+    dataset_version = int(Prompt.ask("\nEnter dataset version to train on (e.g., 1)"))
+
+    if not any(v == dataset_version for v, _ in datasets):
+        console.print("[red]✗ Dataset not found[/red]")
+        return
+
+    labeled_file = get_dataset_labeled_path(dataset_version)
+    if not labeled_file:
+        console.print("[red]✗ Dataset labeled.jsonl not found[/red]")
+        return
+
     duration_minutes = float(Prompt.ask("Training budget (minutes)", default="60"))
     epochs_per_season = int(Prompt.ask("Max epochs per season", default="50"))
     early_stopping_patience = int(Prompt.ask("Early stopping patience (epochs)", default="10"))
 
-    # Data file
-    default_labels = str(get_data_dir() / "training_data.jsonl")
-    labels_file = Prompt.ask("Path to labeled data file (.jsonl)", default=default_labels)
-
     # Optional initial checkpoint
     available = list_checkpoints()
     checkpoint = None
@@ -317,29 +730,25 @@ def burst_train_interactive():
 
     # Summary
     console.print("\n[bold]Configuration Summary:[/bold]")
+    console.print(f"  Dataset:             ds_v{dataset_version}")
     console.print(f"  Duration:            {duration_minutes:.0f} minutes")
     console.print(f"  Epochs per season:   {epochs_per_season}")
     console.print(f"  Patience:            {early_stopping_patience}")
-    console.print(f"  Data file:           {labels_file}")
-    console.print(f"  Checkpoint:          {checkpoint or 'None (from scratch)'}")
     console.print(f"  Batch size:          {batch_size}")
     console.print(f"  Subsample ratio:     {subsample_ratio:.0%}")
+    console.print(f"  Checkpoint:          {checkpoint or 'None (from scratch)'}")
 
     if not Confirm.ask("\nStart burst training?", default=True):
         console.print("[yellow]Burst training cancelled[/yellow]")
+        Prompt.ask("Press Enter to continue")
         return
 
     weights_dir = get_weights_dir()
 
     try:
-        if not Path(labels_file).exists():
-            console.print(f"[red]✗ Data file not found: {labels_file}[/red]")
-            Prompt.ask("Press Enter to continue")
-            return
-
         console.print("\n[bold cyan]Burst Training[/bold cyan]")
         burst_train(
-            data_file=labels_file,
+            data_file=str(labeled_file),
             output_file=str(weights_dir / "nnue_weights.pt"),
             duration_minutes=duration_minutes,
             epochs_per_season=epochs_per_season,
@@ -362,6 +771,7 @@ def burst_train_interactive():
         traceback.print_exc()
         Prompt.ask("Press Enter to continue")
 
+
 def export_interactive():
     """Interactive export menu."""
     console = Console()
@@ -380,7 +790,7 @@ def export_interactive():
     version = Prompt.ask("Enter version to export (e.g., 2)")
 
     weights_file = f"nnue_weights_v{version}.pt"
-    output_file = str(Path(__file__).parent.parent / "src" / "main" / "resources" / "nnue_weights.bin")
+    output_file = str(Path(__file__).parent.parent / "src" / "main" / "resources" / "nnue_weights.nbai")
 
     console.print(f"\n[bold]Export Configuration:[/bold]")
     console.print(f"  Source: {weights_file}")
@@ -399,7 +809,7 @@ def export_interactive():
             return
 
         console.print("\n[bold cyan]Exporting Weights[/bold cyan]")
-        export_weights_to_binary(str(weights_path), output_file)
+        export_to_nbai(str(weights_path), output_file)
         console.print(f"\n[green]✓ Export complete![/green]")
         console.print(f"[bold]Weights saved to:[/bold] {output_file}")
         Prompt.ask("Press Enter to continue")
@@ -410,65 +820,6 @@ def export_interactive():
         traceback.print_exc()
         Prompt.ask("Press Enter to continue")
 
-def extract_tactical_interactive():
-    """Interactive tactical positions extraction and merge menu."""
-    console = Console()
-    show_header()
-
-    console.print("\n[bold cyan]♟️  Tactical Positions Extraction & Merge[/bold cyan]")
-
-    # Download and extract options
-    console.print("\n[bold]Lichess Puzzle Database:[/bold]")
-    download_url = Prompt.ask(
-        "Download URL",
-        default="https://database.lichess.org/lichess_db_puzzle.csv.zst"
-    )
-
-    output_dir = Prompt.ask(
-        "Extract to directory",
-        default=str(Path(__file__).parent / "trainingdata")
-    )
-
-    max_puzzles = int(Prompt.ask("Maximum puzzles to extract", default="300000"))
-
-    # Confirm and download
-    console.print("\n[bold]Configuration:[/bold]")
-    console.print(f"  Download URL: {download_url}")
-    console.print(f"  Extract directory: {output_dir}")
-    console.print(f"  Max puzzles: {max_puzzles:,}")
-
-    if not Confirm.ask("\nProceed?", default=True):
-        console.print("[yellow]Cancelled[/yellow]")
-        Prompt.ask("Press Enter to continue")
-        return
-
-    try:
-        console.print("\n[bold cyan]Step 1: Download & Extract[/bold cyan]")
-        csv_path = download_and_extract_puzzle_db(download_url, output_dir)
-
-        if not csv_path:
-            console.print("[red]✗ Failed to download/extract[/red]")
-            Prompt.ask("Press Enter to continue")
-            return
-
-        console.print(f"[green]✓ Ready: {csv_path}[/green]")
-
-        # Interactive merge
-        console.print("\n[bold cyan]Step 2: Extract & Merge[/bold cyan]")
-        output_file = Prompt.ask(
-            "Output file path",
-            default=str(Path(__file__).parent / "data" / "position.txt")
-        )
-
-        interactive_merge_positions(csv_path, output_file, max_puzzles)
-        console.print(f"\n[green]✓ Complete![/green]")
-        Prompt.ask("Press Enter to continue")
-
-    except Exception as e:
-        console.print(f"[red]✗ Error: {e}[/red]")
-        import traceback
-        traceback.print_exc()
-        Prompt.ask("Press Enter to continue")
 
 def main():
     try:
@@ -481,7 +832,10 @@ def main():
     except Exception as e:
         console = Console()
         console.print(f"[red]Error:[/red] {e}")
+        import traceback
+        traceback.print_exc()
         return 1
 
+
 if __name__ == "__main__":
     sys.exit(main())

modules/bot/python/src/dataset.py

@@ -0,0 +1,287 @@
+#!/usr/bin/env python3
+"""Dataset versioning and management for NNUE training data."""
+
+import json
+from pathlib import Path
+from datetime import datetime
+from typing import Optional, Dict, List, Tuple
+from rich.console import Console
+from rich.table import Table
+
+
+def get_datasets_dir() -> Path:
+    """Get/create datasets directory."""
+    datasets_dir = Path(__file__).parent.parent / "datasets"
+    datasets_dir.mkdir(exist_ok=True)
+    return datasets_dir
+
+
+def next_dataset_version() -> int:
+    """Find the next available dataset version number."""
+    datasets_dir = get_datasets_dir()
+    versions = []
+
+    for d in datasets_dir.iterdir():
+        if d.is_dir() and d.name.startswith("ds_v"):
+            try:
+                v = int(d.name.split("_v")[1])
+                versions.append(v)
+            except (ValueError, IndexError):
+                pass
+
+    return max(versions) + 1 if versions else 1
+
+
+def list_datasets() -> List[Tuple[int, Dict]]:
+    """List all datasets with their metadata.
+
+    Returns:
+        List of (version, metadata_dict) tuples, sorted by version.
+    """
+    datasets_dir = get_datasets_dir()
+    datasets = []
+
+    for d in datasets_dir.iterdir():
+        if d.is_dir() and d.name.startswith("ds_v"):
+            try:
+                v = int(d.name.split("_v")[1])
+                metadata_file = d / "metadata.json"
+                if metadata_file.exists():
+                    with open(metadata_file, 'r') as f:
+                        metadata = json.load(f)
+                    datasets.append((v, metadata))
+            except (ValueError, IndexError, json.JSONDecodeError):
+                pass
+
+    return sorted(datasets, key=lambda x: x[0])
+
+
+def load_dataset_metadata(version: int) -> Optional[Dict]:
+    """Load metadata for a specific dataset version.
+
+    Returns:
+        Metadata dict or None if not found.
+    """
+    datasets_dir = get_datasets_dir()
+    metadata_file = datasets_dir / f"ds_v{version}" / "metadata.json"
+
+    if not metadata_file.exists():
+        return None
+
+    with open(metadata_file, 'r') as f:
+        return json.load(f)
+
+
+def save_dataset_metadata(version: int, metadata: Dict) -> None:
+    """Save metadata for a dataset version."""
+    datasets_dir = get_datasets_dir()
+    dataset_dir = datasets_dir / f"ds_v{version}"
+    dataset_dir.mkdir(exist_ok=True)
+
+    metadata_file = dataset_dir / "metadata.json"
+    with open(metadata_file, 'w') as f:
+        json.dump(metadata, f, indent=2, default=str)
+
+
+def create_dataset(
+    version: int,
+    labeled_jsonl_path: str,
+    sources: List[Dict],
+    stockfish_depth: int = 12
+) -> Path:
+    """Create a new versioned dataset.
+
+    Args:
+        version: Dataset version number
+        labeled_jsonl_path: Path to labeled.jsonl to copy
+        sources: List of source dicts (see plan for schema)
+        stockfish_depth: Depth used for labeling
+
+    Returns:
+        Path to the created dataset directory.
+    """
+    datasets_dir = get_datasets_dir()
+    dataset_dir = datasets_dir / f"ds_v{version}"
+    dataset_dir.mkdir(exist_ok=True)
+
+    # Copy labeled data with deduplication (in case source has duplicates)
+    source_path = Path(labeled_jsonl_path)
+    if source_path.exists():
+        dest_path = dataset_dir / "labeled.jsonl"
+        seen_fens = set()
+        unique_count = 0
+
+        with open(source_path, 'r') as src, open(dest_path, 'w') as dst:
+            for line in src:
+                try:
+                    data = json.loads(line)
+                    fen = data.get('fen')
+                    if fen and fen not in seen_fens:
+                        dst.write(line)
+                        seen_fens.add(fen)
+                        unique_count += 1
+                except json.JSONDecodeError:
+                    # Skip malformed lines
+                    pass
+
+    # Count positions
+    total_positions = 0
+    if (dataset_dir / "labeled.jsonl").exists():
+        with open(dataset_dir / "labeled.jsonl", 'r') as f:
+            total_positions = sum(1 for _ in f)
+
+    # Create metadata
+    metadata = {
+        "version": version,
+        "created": datetime.now().isoformat(),
+        "total_positions": total_positions,
+        "stockfish_depth": stockfish_depth,
+        "sources": sources
+    }
+
+    save_dataset_metadata(version, metadata)
+    return dataset_dir
+
+
+def extend_dataset(
+    version: int,
+    new_labeled_path: str,
+    new_source_entry: Dict
+) -> bool:
+    """Extend an existing dataset with new labeled positions (with deduplication).
+
+    Args:
+        version: Dataset version to extend
+        new_labeled_path: Path to new labeled.jsonl to merge
+        new_source_entry: Source entry to add to metadata
+
+    Returns:
+        True if successful, False otherwise.
+    """
+    datasets_dir = get_datasets_dir()
+    dataset_dir = datasets_dir / f"ds_v{version}"
+
+    if not dataset_dir.exists():
+        return False
+
+    labeled_file = dataset_dir / "labeled.jsonl"
+    new_labeled_file = Path(new_labeled_path)
+
+    if not new_labeled_file.exists():
+        return False
+
+    # Load existing FENs (dedup set) — must load entire file to avoid duplicates
+    existing_fens = set()
+    if labeled_file.exists():
+        with open(labeled_file, 'r') as f:
+            for line in f:
+                try:
+                    data = json.loads(line)
+                    fen = data.get('fen')
+                    if fen:
+                        existing_fens.add(fen)
+                except json.JSONDecodeError:
+                    pass
+
+    # Merge new positions, skipping duplicates
+    new_count = 0
+    new_lines = []
+    with open(new_labeled_file, 'r') as f_new:
+        for line in f_new:
+            try:
+                data = json.loads(line)
+                fen = data.get('fen')
+                if fen and fen not in existing_fens:
+                    new_lines.append(line)
+                    existing_fens.add(fen)
+                    new_count += 1
+            except json.JSONDecodeError:
+                pass
+
+    # Append only the new, unique positions
+    if new_lines:
+        with open(labeled_file, 'a') as f_append:
+            for line in new_lines:
+                f_append.write(line)
+
+    # Update metadata
+    metadata = load_dataset_metadata(version)
+    if metadata:
+        # Count total positions
+        total_positions = 0
+        with open(labeled_file, 'r') as f:
+            total_positions = sum(1 for _ in f)
+
+        metadata['total_positions'] = total_positions
+        # Update the source entry with actual count of new positions added
+        new_source_entry['actual_count'] = new_count
+        metadata['sources'].append(new_source_entry)
+        save_dataset_metadata(version, metadata)
+
+    return True
+
+
+def get_dataset_labeled_path(version: int) -> Optional[Path]:
+    """Get the path to a dataset's labeled.jsonl file.
+
+    Returns:
+        Path to labeled.jsonl or None if dataset doesn't exist.
+    """
+    datasets_dir = get_datasets_dir()
+    labeled_file = datasets_dir / f"ds_v{version}" / "labeled.jsonl"
+
+    if labeled_file.exists():
+        return labeled_file
+    return None
+
+
+def delete_dataset(version: int) -> bool:
+    """Delete a dataset (recursively removes directory).
+
+    Args:
+        version: Dataset version to delete
+
+    Returns:
+        True if successful.
+    """
+    datasets_dir = get_datasets_dir()
+    dataset_dir = datasets_dir / f"ds_v{version}"
+
+    if not dataset_dir.exists():
+        return False
+
+    import shutil
+    shutil.rmtree(dataset_dir)
+    return True
+
+
+def show_datasets_table(console: Console = None) -> None:
+    """Display all datasets in a Rich table."""
+    if console is None:
+        console = Console()
+
+    datasets = list_datasets()
+
+    if not datasets:
+        console.print("[yellow]ℹ No datasets found yet[/yellow]")
+        return
+
+    table = Table(title="Available Datasets", show_header=True, header_style="bold cyan")
+    table.add_column("Version", style="dim")
+    table.add_column("Positions", justify="right")
+    table.add_column("Sources", justify="left")
+    table.add_column("Depth", justify="center")
+    table.add_column("Created", justify="left")
+
+    for v, metadata in datasets:
+        positions = metadata.get('total_positions', 0)
+        sources = metadata.get('sources', [])
+        source_str = ", ".join([s.get('type', '?') for s in sources])
+        depth = metadata.get('stockfish_depth', '?')
+        created = metadata.get('created', '?')
+        if created != '?':
+            created = created.split('T')[0]  # Just the date
+
+        table.add_row(f"v{v}", f"{positions:,}", source_str, str(depth), created)
+
+    console.print(table)

modules/bot/python/src/export.py

@@ -1,67 +1,137 @@
 #!/usr/bin/env python3
-"""Export NNUE weights to binary format for runtime loading."""
+"""Export NNUE weights to .nbai format for runtime loading."""
 
-import torch
+import json
 import struct
 import sys
+from datetime import datetime
 from pathlib import Path
 
-def export_weights_to_binary(weights_file, output_file):
-    """Load PyTorch weights and export as binary file."""
+import torch
 
-    if not Path(weights_file).exists():
-        print(f"Error: Weights file not found at {weights_file}")
-        sys.exit(1)
+MAGIC = 0x4942_414E   # bytes 'N','B','A','I' as little-endian int32
+VERSION = 1
 
-    # Load weights — handle both raw state dicts and full training checkpoints
-    loaded = torch.load(weights_file, map_location='cpu')
-    state_dict = loaded["model_state_dict"] if isinstance(loaded, dict) and "model_state_dict" in loaded else loaded
 
-    # Debug: print available layers
-    print(f"Available layers in {weights_file}:")
-    for key in sorted(state_dict.keys()):
-        print(f"  {key}: {state_dict[key].shape}")
+def _read_sidecar(weights_file: str) -> dict:
+    sidecar = weights_file.replace(".pt", "_metadata.json")
+    if Path(sidecar).exists():
+        with open(sidecar) as f:
+            return json.load(f)
+    return {}
 
-    # Create output directory if needed
-    output_path = Path(output_file)
-    output_path.parent.mkdir(parents=True, exist_ok=True)
 
-    with open(output_file, 'wb') as f:
-        # Write magic number and version
-        f.write(b'NNUE')
-        f.write(struct.pack('<I', 1))  # version 1
+def _infer_layers(state_dict: dict) -> list[dict]:
+    """Derive layer descriptors from state_dict weight shapes.
 
-        # Write each weight tensor in order
-        for layer_name in ['l1.weight', 'l1.bias', 'l2.weight', 'l2.bias', 'l3.weight', 'l3.bias', 'l4.weight', 'l4.bias', 'l5.weight', 'l5.bias']:
-            if layer_name not in state_dict:
-                print(f"Error: Missing layer {layer_name}")
-                sys.exit(1)
+    Assumes layers named l1, l2, ..., lN.
+    All hidden layers get activation 'relu'; the last gets 'linear'.
+    """
+    names = sorted(
+        {k.split(".")[0] for k in state_dict if k.endswith(".weight")},
+        key=lambda n: int(n[1:]),
+    )
+    layers = []
+    for i, name in enumerate(names):
+        out_size, in_size = state_dict[f"{name}.weight"].shape
+        activation = "linear" if i == len(names) - 1 else "relu"
+        layers.append({"activation": activation, "inputSize": int(in_size), "outputSize": int(out_size)})
+    return layers
 
-            tensor = state_dict[layer_name]
-            # Convert to float32 and flatten
+
+def _write_floats(f, tensor):
     data = tensor.float().flatten().cpu().numpy()
+    f.write(struct.pack("<I", len(data)))
+    f.write(struct.pack(f"<{len(data)}f", *data))
 
-            # Write shape (allows validation on load)
-            shape = list(tensor.shape)
-            f.write(struct.pack('<I', len(shape)))
-            for dim in shape:
-                f.write(struct.pack('<I', dim))
 
-            # Write flattened data as binary floats
-            f.write(struct.pack(f'<{len(data)}f', *data))
+def export_to_nbai(
+    weights_file: str,
+    output_file: str,
+    trained_by: str = "unknown",
+    train_loss: float = 0.0,
+):
+    if not Path(weights_file).exists():
+        print(f"Error: weights file not found at {weights_file}")
+        sys.exit(1)
 
-            print(f"  {layer_name}: shape {shape}, {len(data)} floats")
+    loaded = torch.load(weights_file, map_location="cpu")
+    state_dict = (
+        loaded["model_state_dict"]
+        if isinstance(loaded, dict) and "model_state_dict" in loaded
+        else loaded
+    )
+
+    sidecar = _read_sidecar(weights_file)
+    val_loss = float(loaded.get("best_val_loss", sidecar.get("final_val_loss", 0.0))) if isinstance(loaded, dict) else 0.0
+    trained_at = sidecar.get("date", datetime.now().isoformat())
+    training_data_count = int(sidecar.get("num_positions", 0))
+
+    metadata = {
+        "trainedBy": trained_by,
+        "trainedAt": trained_at,
+        "trainingDataCount": training_data_count,
+        "valLoss": val_loss,
+        "trainLoss": train_loss,
+    }
+
+    layers = _infer_layers(state_dict)
+    layer_names = sorted(
+        {k.split(".")[0] for k in state_dict if k.endswith(".weight")},
+        key=lambda n: int(n[1:]),
+    )
+
+    print(f"Architecture ({len(layers)} layers):")
+    for i, l in enumerate(layers):
+        print(f"  l{i + 1}: {l['inputSize']} -> {l['outputSize']}  [{l['activation']}]")
+
+    Path(output_file).parent.mkdir(parents=True, exist_ok=True)
+
+    with open(output_file, "wb") as f:
+        # Header
+        f.write(struct.pack("<I", MAGIC))
+        f.write(struct.pack("<H", VERSION))
+
+        # Metadata (length-prefixed UTF-8 JSON)
+        meta_bytes = json.dumps(metadata, indent=2).encode("utf-8")
+        f.write(struct.pack("<I", len(meta_bytes)))
+        f.write(meta_bytes)
+
+        # Layer descriptors
+        f.write(struct.pack("<H", len(layers)))
+        for layer in layers:
+            name_bytes = layer["activation"].encode("ascii")
+            f.write(struct.pack("<B", len(name_bytes)))
+            f.write(name_bytes)
+            f.write(struct.pack("<I", layer["inputSize"]))
+            f.write(struct.pack("<I", layer["outputSize"]))
+
+        # Weights: weight tensor then bias tensor per layer
+        for name in layer_names:
+            w = state_dict[f"{name}.weight"]
+            b = state_dict[f"{name}.bias"]
+            _write_floats(f, w)
+            _write_floats(f, b)
+            print(f"  Wrote {name}: weight {tuple(w.shape)}, bias {tuple(b.shape)}")
+
+    size_mb = Path(output_file).stat().st_size / (1024 ** 2)
+    print(f"\nExported to {output_file} ({size_mb:.2f} MB)")
+    print(f"Metadata: {json.dumps(metadata, indent=2)}")
 
-    file_size_mb = output_path.stat().st_size / (1024**2)
-    print(f"Weights exported to {output_file} ({file_size_mb:.2f} MB)")
 
 if __name__ == "__main__":
     weights_file = "nnue_weights.pt"
-    output_file = "../src/main/resources/nnue_weights.bin"
+    output_file = "../src/main/resources/nnue_weights.nbai"
+    trained_by = "unknown"
+    train_loss = 0.0
 
     if len(sys.argv) > 1:
         weights_file = sys.argv[1]
     if len(sys.argv) > 2:
         output_file = sys.argv[2]
+    if len(sys.argv) > 3:
+        trained_by = sys.argv[3]
+    if len(sys.argv) > 4:
+        train_loss = float(sys.argv[4])
 
-    export_weights_to_binary(weights_file, output_file)
+    export_to_nbai(weights_file, output_file, trained_by, train_loss)

modules/bot/python/src/label.py

@@ -125,6 +125,7 @@ def label_positions_with_stockfish(positions_file, output_file, stockfish_path,
 
     # Load all FENs that need evaluation
     fens_to_evaluate = []
+    fens_seen_in_batch = set()  # Track duplicates within current batch
     skipped_invalid = 0
     skipped_duplicate = 0
 
@@ -140,7 +141,12 @@ def label_positions_with_stockfish(positions_file, output_file, stockfish_path,
                 skipped_duplicate += 1
                 continue
 
+            if fen in fens_seen_in_batch:
+                skipped_duplicate += 1
+                continue
+
             fens_to_evaluate.append(fen)
+            fens_seen_in_batch.add(fen)
 
     total_to_evaluate = len(fens_to_evaluate)
     total_lines = position_count + skipped_duplicate + skipped_invalid + total_to_evaluate
@@ -178,8 +184,13 @@ def label_positions_with_stockfish(positions_file, output_file, stockfish_path,
             with open(output_file, 'a') as out:
                 for batch_idx, batch_results in enumerate(pool.imap_unordered(_evaluate_fen_batch, batches)):
                     for fen, eval_normalized, eval_cp in batch_results:
+                        # Skip if already evaluated in output file during this run
+                        if fen in evaluated_fens:
+                            continue
+
                         data = {"fen": fen, "eval": eval_normalized, "eval_raw": eval_cp}
                         out.write(json.dumps(data) + '\n')
+                        evaluated_fens.add(fen)  # Track as evaluated
                         evaluated += 1
                         raw_evals.append(eval_cp)
                         normalized_evals.append(eval_normalized)
@@ -287,7 +298,7 @@ if __name__ == "__main__":
                         help="Path to Stockfish binary (default: $STOCKFISH_PATH or 'stockfish')")
     parser.add_argument("--depth", type=int, default=12,
                         help="Stockfish depth (default: 12)")
-    parser.add_argument("--batch-size", type=int, default=20,
+    parser.add_argument("--batch-size", type=int, default=1000,
                         help="Batch size for processing (default: 1000)")
     parser.add_argument("--no-normalize", action="store_true",
                         help="Disable evaluation normalization (keep raw centipawns)")

modules/bot/python/src/tactical_positions_extractor.py

@@ -17,7 +17,7 @@ from generate import play_random_game_and_collect_positions
 
 def download_and_extract_puzzle_db(
         url: str = 'https://database.lichess.org/lichess_db_puzzle.csv.zst',
-        output_dir: str = 'trainingdata'
+        output_dir: str = 'tactical_data'
 ):
     """Download and extract the Lichess puzzle database."""
     output_path = Path(output_dir)
@@ -141,6 +141,31 @@ def merge_positions(
     print(f"{'='*60}\n")
 
 
+def extract_tactical_only(
+        puzzle_csv: str,
+        output_file: str,
+        max_puzzles: int = 300_000
+) -> int:
+    """Extract tactical positions and save to file (no merge prompts).
+
+    Args:
+        puzzle_csv: Path to Lichess puzzle CSV
+        output_file: Where to save the FEN positions
+        max_puzzles: Maximum puzzles to extract
+
+    Returns:
+        Number of positions extracted
+    """
+    print("Extracting tactical positions from puzzle database...")
+    tactical_positions = extract_puzzle_positions(puzzle_csv, max_puzzles)
+
+    with open(output_file, 'w') as f:
+        for fen in tactical_positions:
+            f.write(fen + '\n')
+
+    return len(tactical_positions)
+
+
 def interactive_merge_positions(
         puzzle_csv: str,
         output_file: str = 'position.txt',

modules/bot/python/weights/nnue_weights_v9_metadata.json

@@ -0,0 +1,17 @@
+{
+  "version": 9,
+  "date": "2026-04-13T20:19:08.123315",
+  "num_positions": 2522562,
+  "stockfish_depth": 12,
+  "final_val_loss": 6.994176222619626e-05,
+  "device": "cuda",
+  "notes": "Win rate vs classical eval: TBD (requires benchmark games)",
+  "mode": "burst",
+  "duration_minutes": 30.0,
+  "epochs_per_season": 50,
+  "early_stopping_patience": 10,
+  "seasons_completed": 3,
+  "batch_size": 16384,
+  "learning_rate": 0.001,
+  "initial_checkpoint": "/home/janis/Workspaces/NowChess/NowChessSystems/modules/bot/python/weights/nnue_weights_v8.pt"
+}

modules/bot/src/main/scala/de/nowchess/bot/bots/nnue/EvaluationNNUE.scala

@@ -6,7 +6,7 @@ import de.nowchess.bot.ai.Evaluation
 
 object EvaluationNNUE extends Evaluation:
 
-  private val nnue = NNUE()
+  private val nnue = NNUE(NbaiLoader.loadDefault())
 
   val CHECKMATE_SCORE: Int = 10_000_000
   val DRAW_SCORE: Int      = 0

modules/bot/src/main/scala/de/nowchess/bot/bots/nnue/NNUE.scala

@@ -3,84 +3,31 @@ package de.nowchess.bot.bots.nnue
 import de.nowchess.api.board.{Board, Color, File, Piece, PieceType, Rank, Square}
 import de.nowchess.api.game.GameContext
 import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
-import java.nio.ByteBuffer
-import java.nio.ByteOrder
 
-class NNUE:
+class NNUE(model: NbaiModel):
 
-  private val (l1Weights, l1Bias, l2Weights, l2Bias, l3Weights, l3Bias, l4Weights, l4Bias, l5Weights, l5Bias) =
-    loadWeights()
+  private val featureSize = model.layers(0).inputSize
+  private val accSize     = model.layers(0).outputSize
 
   // Column-major L1 weights for cache-friendly sparse & incremental updates.
-  // l1WeightsT(featureIdx * 1536 + outputIdx) = l1Weights(outputIdx * 768 + featureIdx)
+  // l1WeightsT(featureIdx * accSize + outputIdx) = l1Weights(outputIdx * featureSize + featureIdx)
   private val l1WeightsT: Array[Float] =
-    val t = new Array[Float](768 * 1536)
-    for j <- 0 until 768; i <- 0 until 1536 do t(j * 1536 + i) = l1Weights(i * 768 + j)
+    val w = model.weights(0).weights
+    val t = new Array[Float](featureSize * accSize)
+    for j <- 0 until featureSize; i <- 0 until accSize do t(j * accSize + i) = w(i * featureSize + j)
     t
 
-  private def loadWeights(): (
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-      Array[Float],
-  ) =
-    val stream = Option(getClass.getResourceAsStream("/nnue_weights.bin"))
-      .getOrElse(sys.error("NNUE weights file not found in resources"))
-
-    try
-      val bytes  = stream.readAllBytes()
-      val buffer = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN)
-
-      val magic = buffer.getInt()
-      if magic != 0x4555_4e4e then sys.error(s"Invalid magic number: 0x${magic.toHexString}")
-
-      val version = buffer.getInt()
-      if version != 1 then sys.error(s"Unsupported weight version: $version")
-
-      val l1w = readTensor(buffer)
-      val l1b = readTensor(buffer)
-      val l2w = readTensor(buffer)
-      val l2b = readTensor(buffer)
-      val l3w = readTensor(buffer)
-      val l3b = readTensor(buffer)
-      val l4w = readTensor(buffer)
-      val l4b = readTensor(buffer)
-      val l5w = readTensor(buffer)
-      val l5b = readTensor(buffer)
-
-      (l1w, l1b, l2w, l2b, l3w, l3b, l4w, l4b, l5w, l5b)
-    finally stream.close()
-
-  private def readTensor(buffer: ByteBuffer): Array[Float] =
-    val shapeLen = buffer.getInt()
-    val shape    = Array.ofDim[Int](shapeLen)
-    for i <- 0 until shapeLen do shape(i) = buffer.getInt()
-    val totalElements = shape.product
-    val floats        = Array.ofDim[Float](totalElements)
-    for i <- 0 until totalElements do floats(i) = buffer.getFloat()
-    floats
-
   // ── Accumulator stack ────────────────────────────────────────────────────
-  // l1Stack(ply) holds the L1 pre-activations (before ReLU) for that ply.
-  // Initialised once at root; each child ply is derived incrementally.
 
   private val MAX_PLY                      = 128
-  private val l1Stack: Array[Array[Float]] = Array.fill(MAX_PLY + 1)(new Array[Float](1536))
+  private val l1Stack: Array[Array[Float]] = Array.fill(MAX_PLY + 1)(new Array[Float](accSize))
 
-  // Shared buffers for the dense L2-L5 layers (single-threaded, non-reentrant).
-  private val l1ReLU   = new Array[Float](1536)
-  private val l2Output = new Array[Float](1024)
-  private val l3Output = new Array[Float](512)
-  private val l4Output = new Array[Float](256)
+  // Shared evaluation buffers: index i holds the output of layers(i) (all except the scalar output layer).
+  private val evalBuffers: Array[Array[Float]] = model.layers.init.map(l => new Array[Float](l.outputSize))
 
   // ── Eval cache ───────────────────────────────────────────────────────────
-  private val EVAL_CACHE_MASK = (1 << 18) - 1L // 256 K slots ≈ 3 MB
+
+  private val EVAL_CACHE_MASK = (1 << 18) - 1L
   private val evalCacheHashes = new Array[Long](1 << 18)
   private val evalCacheScores = new Array[Int](1 << 18)
 
@@ -93,25 +40,23 @@ class NNUE:
     (colorOffset + piece.pieceType.ordinal) * 64 + sqNum
 
   private def addColumn(l1Pre: Array[Float], featureIdx: Int): Unit =
-    val offset = featureIdx * 1536
-    for i <- 0 until 1536 do l1Pre(i) += l1WeightsT(offset + i)
+    val offset = featureIdx * accSize
+    for i <- 0 until accSize do l1Pre(i) += l1WeightsT(offset + i)
 
   private def subtractColumn(l1Pre: Array[Float], featureIdx: Int): Unit =
-    val offset = featureIdx * 1536
-    for i <- 0 until 1536 do l1Pre(i) -= l1WeightsT(offset + i)
+    val offset = featureIdx * accSize
+    for i <- 0 until accSize do l1Pre(i) -= l1WeightsT(offset + i)
 
   // ── Accumulator init ─────────────────────────────────────────────────────
 
-  /** Initialise l1Stack(0) from scratch using sparse active features. */
   def initAccumulator(board: Board): Unit =
-    System.arraycopy(l1Bias, 0, l1Stack(0), 0, 1536)
+    System.arraycopy(model.weights(0).bias, 0, l1Stack(0), 0, accSize)
     for (sq, piece) <- board.pieces do addColumn(l1Stack(0), featureIndex(piece, squareNum(sq)))
 
   // ── Accumulator push (incremental updates) ───────────────────────────────
 
-  /** Copy parent ply's pre-activations to childPly, then apply move deltas. */
   def pushAccumulator(childPly: Int, move: Move, board: Board): Unit =
-    System.arraycopy(l1Stack(childPly - 1), 0, l1Stack(childPly), 0, 1536)
+    System.arraycopy(l1Stack(childPly - 1), 0, l1Stack(childPly), 0, accSize)
     val l1 = l1Stack(childPly)
     move.moveType match
       case MoveType.Normal(_)                                  => applyNormalDelta(l1, move, board)
@@ -119,9 +64,8 @@ class NNUE:
       case MoveType.CastleKingside | MoveType.CastleQueenside  => applyCastleDelta(l1, move, board)
       case MoveType.Promotion(p)                               => applyPromotionDelta(l1, move, p, board)
 
-  /** Copy pre-activations from parentPly to childPly without any move delta (null-move). */
   def copyAccumulator(parentPly: Int, childPly: Int): Unit =
-    System.arraycopy(l1Stack(parentPly), 0, l1Stack(childPly), 0, 1536)
+    System.arraycopy(l1Stack(parentPly), 0, l1Stack(childPly), 0, accSize)
 
   private def applyNormalDelta(l1: Array[Float], move: Move, board: Board): Unit =
     board.pieceAt(move.from).foreach { mover =>
@@ -170,9 +114,6 @@ class NNUE:
 
   // ── Evaluation from accumulator ──────────────────────────────────────────
 
-  /** Evaluate from pre-computed L1 pre-activations at the given ply. Probes eval cache first; stores result after
-    * computation.
-    */
   def evaluateAtPly(ply: Int, turn: Color, hash: Long): Int =
     val idx = (hash & EVAL_CACHE_MASK).toInt
     if evalCacheHashes(idx) == hash then evalCacheScores(idx)
@@ -183,11 +124,19 @@ class NNUE:
       score
 
   private def runL2toOutput(l1Pre: Array[Float], turn: Color): Int =
-    for i <- 0 until 1536 do l1ReLU(i) = if l1Pre(i) > 0f then l1Pre(i) else 0f
-    runDenseReLU(l1ReLU, 1536, l2Weights, l2Bias, l2Output, 1024)
-    runDenseReLU(l2Output, 1024, l3Weights, l3Bias, l3Output, 512)
-    runDenseReLU(l3Output, 512, l4Weights, l4Bias, l4Output, 256)
-    val output = runOutputLayer(l4Output, 256)
+    val l1ReLU = evalBuffers(0)
+    for i <- 0 until accSize do l1ReLU(i) = if l1Pre(i) > 0f then l1Pre(i) else 0f
+
+    var input = l1ReLU
+    for i <- 1 until model.layers.length - 1 do
+      val lw  = model.weights(i)
+      val out = evalBuffers(i)
+      val ld  = model.layers(i)
+      runDenseReLU(input, ld.inputSize, lw.weights, lw.bias, out, ld.outputSize)
+      input = out
+
+    val lastIdx = model.layers.length - 1
+    val output  = runOutputLayer(input, model.layers(lastIdx).inputSize, model.weights(lastIdx))
     scoreFromOutput(output, turn)
 
   private def runDenseReLU(
@@ -202,8 +151,8 @@ class NNUE:
       val sum = (0 until inSize).foldLeft(bias(i))((s, j) => s + input(j) * weights(i * inSize + j))
       output(i) = if sum > 0f then sum else 0f
 
-  private def runOutputLayer(input: Array[Float], inSize: Int): Float =
-    (0 until inSize).foldLeft(l5Bias(0))((sum, j) => sum + input(j) * l5Weights(j))
+  private def runOutputLayer(input: Array[Float], inSize: Int, lw: LayerWeights): Float =
+    (0 until inSize).foldLeft(lw.bias(0))((sum, j) => sum + input(j) * lw.weights(j))
 
   private def scoreFromOutput(output: Float, turn: Color): Int =
     val cp =
@@ -214,21 +163,15 @@ class NNUE:
     val cpFromTurn = if turn == Color.Black then -cp else cp
     math.max(-20000, math.min(20000, cpFromTurn))
 
-  // ── Legacy full-board evaluate (kept for Evaluation.evaluate compatibility) ──
+  // ── Legacy full-board evaluate ────────────────────────────────────────────
 
-  // Pre-allocated buffers used only by the legacy evaluate path.
-  private val features = new Array[Float](768)
-  private val legacyL1 = new Array[Float](1536)
+  private val legacyL1 = new Array[Float](accSize)
 
-  /** Evaluate using full board scan (sparse over active features). Layout: black pieces at indices 0-5, white at 6-11.
-    */
   def evaluate(context: GameContext): Int =
-    val l1Pre = legacyL1
-    System.arraycopy(l1Bias, 0, l1Pre, 0, 1536)
-    for (sq, piece) <- context.board.pieces do addColumn(l1Pre, featureIndex(piece, squareNum(sq)))
-    runL2toOutput(l1Pre, context.turn)
+    System.arraycopy(model.weights(0).bias, 0, legacyL1, 0, accSize)
+    for (sq, piece) <- context.board.pieces do addColumn(legacyL1, featureIndex(piece, squareNum(sq)))
+    runL2toOutput(legacyL1, context.turn)
 
-  /** Benchmark: time 1M evaluations and report ns/eval. */
   def benchmark(): Unit =
     val context    = GameContext.initial
     val iterations = 1_000_000

modules/bot/src/main/scala/de/nowchess/bot/bots/nnue/NbaiLoader.scala

@@ -0,0 +1,50 @@
+package de.nowchess.bot.bots.nnue
+
+import java.io.InputStream
+import java.nio.{ByteBuffer, ByteOrder}
+import java.nio.charset.StandardCharsets
+
+object NbaiLoader:
+
+  /** Little-endian encoding of ASCII bytes 'N','B','A','I'. */
+  val MAGIC: Int = 0x4942_414e
+
+  def load(stream: InputStream): NbaiModel =
+    val buf = ByteBuffer.wrap(stream.readAllBytes()).order(ByteOrder.LITTLE_ENDIAN)
+    checkHeader(buf)
+    val metadata = readMetadata(buf)
+    val descs    = readLayerDescriptors(buf)
+    val weights  = descs.map(_ => readLayerWeights(buf))
+    NbaiModel(metadata, descs, weights)
+
+  /** Tries /nnue_weights.nbai on the classpath; falls back to migrating /nnue_weights.bin. */
+  def loadDefault(): NbaiModel =
+    Option(getClass.getResourceAsStream("/nnue_weights.nbai")) match
+      case Some(s) => try load(s) finally s.close()
+      case None    => NbaiMigrator.migrateFromBin()
+
+  private def checkHeader(buf: ByteBuffer): Unit =
+    val magic = buf.getInt()
+    if magic != MAGIC then sys.error(s"Invalid NBAI magic: 0x${magic.toHexString}")
+    val version = buf.getShort() & 0xffff
+    if version != 1 then sys.error(s"Unsupported NBAI version: $version")
+
+  private def readMetadata(buf: ByteBuffer): NbaiMetadata =
+    val bytes = new Array[Byte](buf.getInt())
+    buf.get(bytes)
+    NbaiMetadata.fromJson(new String(bytes, StandardCharsets.UTF_8))
+
+  private def readLayerDescriptors(buf: ByteBuffer): Array[LayerDescriptor] =
+    Array.tabulate(buf.getShort() & 0xffff) { _ =>
+      val nameBytes = new Array[Byte](buf.get() & 0xff)
+      buf.get(nameBytes)
+      LayerDescriptor(new String(nameBytes, StandardCharsets.US_ASCII), buf.getInt(), buf.getInt())
+    }
+
+  private def readLayerWeights(buf: ByteBuffer): LayerWeights =
+    LayerWeights(readFloats(buf), readFloats(buf))
+
+  private def readFloats(buf: ByteBuffer): Array[Float] =
+    val arr = new Array[Float](buf.getInt())
+    for i <- arr.indices do arr(i) = buf.getFloat()
+    arr

modules/bot/src/main/scala/de/nowchess/bot/bots/nnue/NbaiMigrator.scala

@@ -0,0 +1,43 @@
+package de.nowchess.bot.bots.nnue
+
+import java.nio.{ByteBuffer, ByteOrder}
+
+/** Converts the legacy nnue_weights.bin resource into an NbaiModel. Used as fallback when no .nbai file exists. */
+object NbaiMigrator:
+
+  private val BinMagic   = 0x4555_4e4e
+  private val BinVersion = 1
+
+  private val DefaultLayers: Array[LayerDescriptor] = Array(
+    LayerDescriptor("relu",    768, 1536),
+    LayerDescriptor("relu",   1536, 1024),
+    LayerDescriptor("relu",   1024,  512),
+    LayerDescriptor("relu",    512,  256),
+    LayerDescriptor("linear",  256,    1),
+  )
+
+  private val UnknownMetadata: NbaiMetadata =
+    NbaiMetadata(trainedBy = "unknown", trainedAt = "unknown", trainingDataCount = 0L, valLoss = 0.0, trainLoss = 0.0)
+
+  def migrateFromBin(): NbaiModel =
+    val stream = Option(getClass.getResourceAsStream("/nnue_weights.bin"))
+      .getOrElse(sys.error("Neither nnue_weights.nbai nor nnue_weights.bin found in resources"))
+    try
+      val buf = ByteBuffer.wrap(stream.readAllBytes()).order(ByteOrder.LITTLE_ENDIAN)
+      checkBinHeader(buf)
+      val weights = DefaultLayers.map(_ => readBinLayerWeights(buf))
+      NbaiModel(UnknownMetadata, DefaultLayers, weights)
+    finally stream.close()
+
+  private def checkBinHeader(buf: ByteBuffer): Unit =
+    val magic = buf.getInt()
+    if magic != BinMagic then sys.error(s"Invalid bin magic: 0x${magic.toHexString}")
+    val version = buf.getInt()
+    if version != BinVersion then sys.error(s"Unsupported bin version: $version")
+
+  private def readBinLayerWeights(buf: ByteBuffer): LayerWeights =
+    LayerWeights(readBinTensor(buf), readBinTensor(buf))
+
+  private def readBinTensor(buf: ByteBuffer): Array[Float] =
+    val shape = Array.tabulate(buf.getInt())(_ => buf.getInt())
+    Array.tabulate(shape.product)(_ => buf.getFloat())

modules/bot/src/main/scala/de/nowchess/bot/bots/nnue/NbaiModel.scala

@@ -0,0 +1,39 @@
+package de.nowchess.bot.bots.nnue
+
+/** Descriptor for a single dense layer stored in a .nbai file. */
+case class LayerDescriptor(activation: String, inputSize: Int, outputSize: Int)
+
+/** Training metadata embedded in every .nbai file. */
+case class NbaiMetadata(
+    trainedBy: String,
+    trainedAt: String,
+    trainingDataCount: Long,
+    valLoss: Double,
+    trainLoss: Double,
+):
+  def toJson: String =
+    s"""{
+       |  "trainedBy": "$trainedBy",
+       |  "trainedAt": "$trainedAt",
+       |  "trainingDataCount": $trainingDataCount,
+       |  "valLoss": $valLoss,
+       |  "trainLoss": $trainLoss
+       |}""".stripMargin
+
+object NbaiMetadata:
+  def fromJson(json: String): NbaiMetadata =
+    def str(key: String) = raw""""$key"\s*:\s*"([^"]*)"""".r.findFirstMatchIn(json).map(_.group(1)).getOrElse("")
+    def num(key: String) = raw""""$key"\s*:\s*([0-9.eE+\-]+)""".r.findFirstMatchIn(json).map(_.group(1)).getOrElse("0")
+    NbaiMetadata(str("trainedBy"), str("trainedAt"), num("trainingDataCount").toLong, num("valLoss").toDouble, num("trainLoss").toDouble)
+
+/** Weights and biases for a single layer. Weights are row-major: (outputSize × inputSize). */
+case class LayerWeights(weights: Array[Float], bias: Array[Float])
+
+/** A fully deserialized .nbai model ready to initialize NNUE. */
+case class NbaiModel(
+    metadata: NbaiMetadata,
+    layers: Array[LayerDescriptor],
+    weights: Array[LayerWeights],
+):
+  require(layers.length == weights.length, "Layer count must match weight count")
+  require(layers.length >= 2, "Model must have at least 2 layers")

modules/bot/src/main/scala/de/nowchess/bot/bots/nnue/NbaiWriter.scala

@@ -0,0 +1,51 @@
+package de.nowchess.bot.bots.nnue
+
+import java.io.{ByteArrayOutputStream, OutputStream}
+import java.nio.{ByteBuffer, ByteOrder}
+import java.nio.charset.StandardCharsets
+
+object NbaiWriter:
+
+  def write(model: NbaiModel, out: OutputStream): Unit =
+    val acc = new ByteArrayOutputStream()
+    writeHeader(acc)
+    writeMetadata(acc, model.metadata)
+    writeLayerDescriptors(acc, model.layers)
+    model.weights.foreach(lw => writeLayerWeights(acc, lw))
+    out.write(acc.toByteArray)
+
+  private def writeHeader(out: ByteArrayOutputStream): Unit =
+    val buf = ByteBuffer.allocate(6).order(ByteOrder.LITTLE_ENDIAN)
+    buf.putInt(NbaiLoader.MAGIC)
+    buf.putShort(1.toShort)
+    out.write(buf.array())
+
+  private def writeMetadata(out: ByteArrayOutputStream, meta: NbaiMetadata): Unit =
+    val json = meta.toJson.getBytes(StandardCharsets.UTF_8)
+    val buf  = ByteBuffer.allocate(4 + json.length).order(ByteOrder.LITTLE_ENDIAN)
+    buf.putInt(json.length)
+    buf.put(json)
+    out.write(buf.array())
+
+  private def writeLayerDescriptors(out: ByteArrayOutputStream, layers: Array[LayerDescriptor]): Unit =
+    val nameBytes = layers.map(_.activation.getBytes(StandardCharsets.US_ASCII))
+    val capacity  = 2 + layers.indices.map(i => 1 + nameBytes(i).length + 8).sum
+    val buf       = ByteBuffer.allocate(capacity).order(ByteOrder.LITTLE_ENDIAN)
+    buf.putShort(layers.length.toShort)
+    layers.zip(nameBytes).foreach { (l, nb) =>
+      buf.put(nb.length.toByte)
+      buf.put(nb)
+      buf.putInt(l.inputSize)
+      buf.putInt(l.outputSize)
+    }
+    out.write(buf.array())
+
+  private def writeLayerWeights(out: ByteArrayOutputStream, lw: LayerWeights): Unit =
+    writeFloats(out, lw.weights)
+    writeFloats(out, lw.bias)
+
+  private def writeFloats(out: ByteArrayOutputStream, floats: Array[Float]): Unit =
+    val buf = ByteBuffer.allocate(4 + floats.length * 4).order(ByteOrder.LITTLE_ENDIAN)
+    buf.putInt(floats.length)
+    floats.foreach(buf.putFloat)
+    out.write(buf.array())