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+# Databento Historical Data Integration Plan
+
+## Overview
+
+Integrate Databento historical API for backtesting and scenario comparison pages, replacing yfinance for historical data on these pages. The integration will support configurable start prices/values independent of portfolio settings, with intelligent caching to avoid redundant downloads.
+
+## Architecture
+
+### Current State
+- **Backtest page** (`app/pages/backtests.py`): Uses `YFinanceHistoricalPriceSource` via `BacktestPageService`
+- **Event comparison** (`app/pages/event_comparison.py`): Uses seeded event presets with yfinance data
+- **Historical provider** (`app/services/backtesting/historical_provider.py`): Protocol-based architecture with `YFinanceHistoricalPriceSource` and `SyntheticHistoricalProvider`
+
+### Target State
+- Add `DatabentoHistoricalPriceSource` implementing `HistoricalPriceSource` protocol
+- Add `DatabentoHistoricalOptionSource` implementing `OptionSnapshotSource` protocol (future)
+- Smart caching layer: only re-download when parameters change
+- Pre-seeded scenario data via batch downloads
+
+## Databento Data Sources
+
+### Underlyings and Datasets
+
+| Instrument | Dataset | Symbol Format | Notes |
+|------------|---------|----------------|-------|
+| GLD ETF | `XNAS.BASIC` or `EQUS.PLUS` | `GLD` | US equities consolidated |
+| GC=F Futures | `GLBX.MDP3` | `GC` + continuous or `GC=F` raw | Gold futures |
+| Gold Options | `OPRA.PILLAR` | `GLD` underlying | Options on GLD ETF |
+
+### Schemas
+
+| Schema | Use Case | Fields |
+|--------|----------|--------|
+| `ohlcv-1d` | Daily backtesting | open, high, low, close, volume |
+| `ohlcv-1h` | Intraday scenarios | Hourly bars |
+| `trades` | Tick-level analysis | Full trade data |
+| `definition` | Instrument metadata | Expiries, strike prices, tick sizes |
+
+## Implementation Plan
+
+### Phase 1: Historical Price Source (DATA-DB-001)
+
+**File:** `app/services/backtesting/databento_source.py`
+
+```python
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import date, timedelta
+from pathlib import Path
+from typing import Any
+import hashlib
+import json
+
+from app.services.backtesting.historical_provider import DailyClosePoint, HistoricalPriceSource
+
+try:
+    import databento as db
+    DATABENTO_AVAILABLE = True
+except ImportError:
+    DATABENTO_AVAILABLE = False
+
+
+@dataclass(frozen=True)
+class DatabentoCacheKey:
+    """Cache key for Databento data requests."""
+    dataset: str
+    symbol: str
+    schema: str
+    start_date: date
+    end_date: date
+    
+    def cache_path(self, cache_dir: Path) -> Path:
+        key_str = f"{self.dataset}_{self.symbol}_{self.schema}_{self.start_date}_{self.end_date}"
+        key_hash = hashlib.sha256(key_str.encode()).hexdigest()[:16]
+        return cache_dir / f"dbn_{key_hash}.parquet"
+    
+    def metadata_path(self, cache_dir: Path) -> Path:
+        key_str = f"{self.dataset}_{self.symbol}_{self.schema}_{self.start_date}_{self.end_date}"
+        key_hash = hashlib.sha256(key_str.encode()).hexdigest()[:16]
+        return cache_dir / f"dbn_{key_hash}_meta.json"
+
+
+@dataclass
+class DatabentoSourceConfig:
+    """Configuration for Databento data source."""
+    api_key: str | None = None  # Falls back to DATABENTO_API_KEY env var
+    cache_dir: Path = Path(".cache/databento")
+    dataset: str = "XNAS.BASIC"
+    schema: str = "ohlcv-1d"
+    stype_in: str = "raw_symbol"
+    
+    # Re-download threshold
+    max_cache_age_days: int = 30
+
+
+class DatabentoHistoricalPriceSource(HistoricalPriceSource):
+    """Databento-based historical price source for backtesting."""
+    
+    def __init__(self, config: DatabentoSourceConfig | None = None) -> None:
+        if not DATABENTO_AVAILABLE:
+            raise RuntimeError("databento package required: pip install databento")
+        
+        self.config = config or DatabentoSourceConfig()
+        self.config.cache_dir.mkdir(parents=True, exist_ok=True)
+        self._client: db.Historical | None = None
+    
+    @property
+    def client(self) -> db.Historical:
+        if self._client is None:
+            self._client = db.Historical(key=self.config.api_key)
+        return self._client
+    
+    def _load_from_cache(self, key: DatabentoCacheKey) -> list[DailyClosePoint] | None:
+        """Load cached data if available and fresh."""
+        cache_file = key.cache_path(self.config.cache_dir)
+        meta_file = key.metadata_path(self.config.cache_dir)
+        
+        if not cache_file.exists() or not meta_file.exists():
+            return None
+        
+        try:
+            with open(meta_file) as f:
+                meta = json.load(f)
+            
+            # Check cache age
+            download_date = date.fromisoformat(meta["download_date"])
+            age_days = (date.today() - download_date).days
+            if age_days > self.config.max_cache_age_days:
+                return None
+            
+            # Check parameters match
+            if meta["dataset"] != key.dataset or meta["symbol"] != key.symbol:
+                return None
+            
+            # Load parquet and convert
+            import pandas as pd
+            df = pd.read_parquet(cache_file)
+            return self._df_to_daily_points(df)
+        except Exception:
+            return None
+    
+    def _save_to_cache(self, key: DatabentoCacheKey, df: pd.DataFrame) -> None:
+        """Save data to cache."""
+        cache_file = key.cache_path(self.config.cache_dir)
+        meta_file = key.metadata_path(self.config.cache_dir)
+        
+        df.to_parquet(cache_file, index=False)
+        
+        meta = {
+            "download_date": date.today().isoformat(),
+            "dataset": key.dataset,
+            "symbol": key.symbol,
+            "schema": key.schema,
+            "start_date": key.start_date.isoformat(),
+            "end_date": key.end_date.isoformat(),
+            "rows": len(df),
+        }
+        with open(meta_file, "w") as f:
+            json.dump(meta, f, indent=2)
+    
+    def _fetch_from_databento(self, key: DatabentoCacheKey) -> pd.DataFrame:
+        """Fetch data from Databento API."""
+        data = self.client.timeseries.get_range(
+            dataset=key.dataset,
+            symbols=key.symbol,
+            schema=key.schema,
+            start=key.start_date.isoformat(),
+            end=(key.end_date + timedelta(days=1)).isoformat(),  # Exclusive end
+            stype_in=self.config.stype_in,
+        )
+        df = data.to_df()
+        return df
+    
+    def _df_to_daily_points(self, df: pd.DataFrame) -> list[DailyClosePoint]:
+        """Convert DataFrame to DailyClosePoint list."""
+        points = []
+        for idx, row in df.iterrows():
+            # Databento ohlcv schema has ts_event as timestamp
+            ts = row.get("ts_event", row.get("ts_recv", idx))
+            if hasattr(ts, "date"):
+                row_date = ts.date()
+            else:
+                row_date = date.fromisoformat(str(ts)[:10])
+            
+            close = float(row["close"]) / 1e9  # Databento prices are int64 x 1e-9
+            
+            points.append(DailyClosePoint(date=row_date, close=close))
+        
+        return sorted(points, key=lambda p: p.date)
+    
+    def load_daily_closes(self, symbol: str, start_date: date, end_date: date) -> list[DailyClosePoint]:
+        """Load daily closing prices from Databento (with caching)."""
+        # Map symbols to datasets
+        dataset = self._resolve_dataset(symbol)
+        databento_symbol = self._resolve_symbol(symbol)
+        
+        key = DatabentoCacheKey(
+            dataset=dataset,
+            symbol=databento_symbol,
+            schema=self.config.schema,
+            start_date=start_date,
+            end_date=end_date,
+        )
+        
+        # Try cache first
+        cached = self._load_from_cache(key)
+        if cached is not None:
+            return cached
+        
+        # Fetch from Databento
+        import pandas as pd
+        df = self._fetch_from_databento(key)
+        
+        # Cache results
+        self._save_to_cache(key, df)
+        
+        return self._df_to_daily_points(df)
+    
+    def _resolve_dataset(self, symbol: str) -> str:
+        """Resolve symbol to Databento dataset."""
+        symbol_upper = symbol.upper()
+        if symbol_upper in ("GLD", "GLDM", "IAU"):
+            return "XNAS.BASIC"  # ETFs on Nasdaq
+        elif symbol_upper in ("GC=F", "GC", "GOLD"):
+            return "GLBX.MDP3"  # CME gold futures
+        elif symbol_upper == "XAU":
+            return "XNAS.BASIC"  # Treat as GLD proxy
+        else:
+            return self.config.dataset  # Use configured default
+    
+    def _resolve_symbol(self, symbol: str) -> str:
+        """Resolve vault-dash symbol to Databento symbol."""
+        symbol_upper = symbol.upper()
+        if symbol_upper == "XAU":
+            return "GLD"  # Proxy XAU via GLD prices
+        elif symbol_upper == "GC=F":
+            return "GC"  # Use parent symbol for continuous contracts
+        return symbol_upper
+    
+    def get_cost_estimate(self, symbol: str, start_date: date, end_date: date) -> float:
+        """Estimate cost in USD for a data request."""
+        dataset = self._resolve_dataset(symbol)
+        databento_symbol = self._resolve_symbol(symbol)
+        
+        try:
+            cost = self.client.metadata.get_cost(
+                dataset=dataset,
+                symbols=databento_symbol,
+                schema=self.config.schema,
+                start=start_date.isoformat(),
+                end=(end_date + timedelta(days=1)).isoformat(),
+            )
+            return cost
+        except Exception:
+            return 0.0  # Return 0 if cost estimation fails
+
+
+class DatabentoBacktestProvider:
+    """Databento-backed historical provider for synthetic backtesting."""
+    
+    provider_id = "databento_v1"
+    pricing_mode = "synthetic_bs_mid"
+    
+    def __init__(
+        self,
+        price_source: DatabentoHistoricalPriceSource,
+        implied_volatility: float = 0.16,
+        risk_free_rate: float = 0.045,
+    ) -> None:
+        self.price_source = price_source
+        self.implied_volatility = implied_volatility
+        self.risk_free_rate = risk_free_rate
+    
+    def load_history(self, symbol: str, start_date: date, end_date: date) -> list[DailyClosePoint]:
+        return self.price_source.load_daily_closes(symbol, start_date, end_date)
+    
+    # ... rest delegates to SyntheticHistoricalProvider logic
+```
+
+### Phase 2: Backtest Settings Model (DATA-DB-002)
+
+**File:** `app/models/backtest_settings.py`
+
+```python
+from dataclasses import dataclass, field
+from datetime import date
+from uuid import UUID
+
+from app.models.backtest import ProviderRef
+
+
+@dataclass(frozen=True)
+class BacktestSettings:
+    """User-configurable backtest settings (independent of portfolio)."""
+    
+    # Scenario identification
+    settings_id: UUID
+    name: str
+    
+    # Data source configuration
+    data_source: str = "databento"  # "databento", "yfinance", "synthetic"
+    dataset: str = "XNAS.BASIC"
+    schema: str = "ohlcv-1d"
+    
+    # Date range
+    start_date: date = date(2024, 1, 1)
+    end_date: date = date(2024, 12, 31)
+    
+    # Independent scenario configuration (not derived from portfolio)
+    underlying_symbol: str = "GLD"
+    start_price: float = 0.0  # 0 = auto-derive from first close
+    underlying_units: float = 1000.0  # Independent of portfolio
+    loan_amount: float = 0.0  # Debt position for LTV analysis
+    margin_call_ltv: float = 0.75
+    
+    # Templates to test
+    template_slugs: tuple[str, ...] = field(default_factory=lambda: ("protective-put-atm-12m",))
+    
+    # Provider reference
+    provider_ref: ProviderRef = field(default_factory=lambda: ProviderRef(
+        provider_id="databento_v1",
+        pricing_mode="synthetic_bs_mid",
+    ))
+    
+    # Cache metadata
+    cache_key: str = ""  # Populated when data is fetched
+    data_cost_usd: float = 0.0  # Cost of last data fetch
+```
+
+### Phase 3: Cache Management (DATA-DB-003)
+
+**File:** `app/services/backtesting/databento_cache.py`
+
+```python
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import date, timedelta
+from pathlib import Path
+import hashlib
+import json
+
+from app.services.backtesting.databento_source import DatabentoCacheKey
+
+
+@dataclass
+class CacheEntry:
+    """Metadata for a cached Databento dataset."""
+    cache_key: DatabentoCacheKey
+    file_path: Path
+    download_date: date
+    size_bytes: int
+    cost_usd: float
+
+
+class DatabentoCacheManager:
+    """Manages Databento data cache lifecycle."""
+    
+    def __init__(self, cache_dir: Path = Path(".cache/databento")) -> None:
+        self.cache_dir = cache_dir
+        self.cache_dir.mkdir(parents=True, exist_ok=True)
+    
+    def list_entries(self) -> list[CacheEntry]:
+        """List all cached entries."""
+        entries = []
+        for meta_file in self.cache_dir.glob("*_meta.json"):
+            with open(meta_file) as f:
+                meta = json.load(f)
+            
+            cache_file = meta_file.with_name(meta_file.stem.replace("_meta", "") + ".parquet")
+            if cache_file.exists():
+                entries.append(CacheEntry(
+                    cache_key=DatabentoCacheKey(
+                        dataset=meta["dataset"],
+                        symbol=meta["symbol"],
+                        schema=meta["schema"],
+                        start_date=date.fromisoformat(meta["start_date"]),
+                        end_date=date.fromisoformat(meta["end_date"]),
+                    ),
+                    file_path=cache_file,
+                    download_date=date.fromisoformat(meta["download_date"]),
+                    size_bytes=cache_file.stat().st_size,
+                    cost_usd=0.0,  # Would need to track separately
+                ))
+        return entries
+    
+    def invalidate_expired(self, max_age_days: int = 30) -> list[Path]:
+        """Remove cache entries older than max_age_days."""
+        removed = []
+        cutoff = date.today() - timedelta(days=max_age_days)
+        
+        for entry in self.list_entries():
+            if entry.download_date < cutoff:
+                entry.file_path.unlink(missing_ok=True)
+                meta_file = entry.file_path.with_name(entry.file_path.stem + "_meta.json")
+                meta_file.unlink(missing_ok=True)
+                removed.append(entry.file_path)
+        
+        return removed
+    
+    def clear_all(self) -> int:
+        """Clear all cached data."""
+        count = 0
+        for file in self.cache_dir.glob("*"):
+            if file.is_file():
+                file.unlink()
+                count += 1
+        return count
+    
+    def get_cache_size(self) -> int:
+        """Get total cache size in bytes."""
+        return sum(f.stat().st_size for f in self.cache_dir.glob("*") if f.is_file())
+    
+    def should_redownload(self, key: DatabentoCacheKey, params_changed: bool) -> bool:
+        """Determine if data should be re-downloaded."""
+        cache_file = key.cache_path(self.cache_dir)
+        meta_file = key.metadata_path(self.cache_dir)
+        
+        if params_changed:
+            return True
+        
+        if not cache_file.exists() or not meta_file.exists():
+            return True
+        
+        try:
+            with open(meta_file) as f:
+                meta = json.load(f)
+            download_date = date.fromisoformat(meta["download_date"])
+            age_days = (date.today() - download_date).days
+            return age_days > 30
+        except Exception:
+            return True
+```
+
+### Phase 4: Backtest Page UI Updates (DATA-DB-004)
+
+**Key changes to `app/pages/backtests.py`:**
+
+1. Add Databento configuration section
+2. Add independent start price/units inputs
+3. Show estimated data cost before fetching
+4. Cache status indicator
+
+```python
+# In backtests.py
+
+with ui.card().classes("w-full ..."):
+    ui.label("Data Source").classes("text-lg font-semibold")
+    
+    data_source = ui.select(
+        {"databento": "Databento (historical market data)", "yfinance": "Yahoo Finance (free, limited)"},
+        value="databento",
+        label="Data source",
+    ).classes("w-full")
+    
+    # Databento-specific settings
+    with ui.column().classes("w-full gap-2").bind_visibility_from(data_source, "value", lambda v: v == "databento"):
+        ui.label("Dataset configuration").classes("text-sm text-slate-500")
+        
+        dataset_select = ui.select(
+            {"XNAS.BASIC": "Nasdaq Basic (GLD)", "GLBX.MDP3": "CME Globex (GC=F)"},
+            value="XNAS.BASIC",
+            label="Dataset",
+        ).classes("w-full")
+        
+        schema_select = ui.select(
+            {"ohlcv-1d": "Daily bars", "ohlcv-1h": "Hourly bars"},
+            value="ohlcv-1d",
+            label="Resolution",
+        ).classes("w-full")
+        
+        # Cost estimate
+        cost_label = ui.label("Estimated cost: $0.00").classes("text-sm text-slate-500")
+        
+        # Cache status
+        cache_status = ui.label("").classes("text-xs text-slate-400")
+    
+    # Independent scenario settings
+    with ui.card().classes("w-full ..."):
+        ui.label("Scenario Configuration").classes("text-lg font-semibold")
+        ui.label("Configure start values independent of portfolio settings").classes("text-sm text-slate-500")
+        
+        start_price_input = ui.number(
+            "Start price",
+            value=0.0,
+            min=0.0,
+            step=0.01,
+        ).classes("w-full")
+        ui.label("Set to 0 to auto-derive from first historical close").classes("text-xs text-slate-400 -mt-2")
+        
+        underlying_units_input = ui.number(
+            "Underlying units",
+            value=1000.0,
+            min=0.0001,
+            step=0.0001,
+        ).classes("w-full")
+        
+        loan_amount_input = ui.number(
+            "Loan amount ($)",
+            value=0.0,
+            min=0.0,
+            step=1000,
+        ).classes("w-full")
+```
+
+### Phase 5: Scenario Pre-Seeding (DATA-DB-005)
+
+**File:** `app/services/backtesting/scenario_bulk_download.py`
+
+```python
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import date
+from pathlib import Path
+import json
+
+try:
+    import databento as db
+    DATABENTO_AVAILABLE = True
+except ImportError:
+    DATABENTO_AVAILABLE = False
+
+
+@dataclass
+class ScenarioPreset:
+    """Pre-configured scenario ready for backtesting."""
+    preset_id: str
+    display_name: str
+    symbol: str
+    dataset: str
+    window_start: date
+    window_end: date
+    default_start_price: float  # First close in window
+    default_templates: tuple[str, ...]
+    event_type: str
+    tags: tuple[str, ...]
+    description: str
+
+
+def download_historical_presets(
+    client: db.Historical,
+    presets: list[ScenarioPreset],
+    output_dir: Path,
+) -> dict[str, Path]:
+    """Bulk download historical data for all presets.
+    
+    Returns mapping of preset_id to cached file path.
+    """
+    results = {}
+    
+    for preset in presets:
+        cache_key = DatabentoCacheKey(
+            dataset=preset.dataset,
+            symbol=preset.symbol,
+            schema="ohlcv-1d",
+            start_date=preset.window_start,
+            end_date=preset.window_end,
+        )
+        
+        cache_file = cache_key.cache_path(output_dir)
+        
+        # Download if not cached
+        if not cache_file.exists():
+            data = client.timeseries.get_range(
+                dataset=preset.dataset,
+                symbols=preset.symbol,
+                schema="ohlcv-1d",
+                start=preset.window_start.isoformat(),
+                end=preset.window_end.isoformat(),
+            )
+            data.to_parquet(cache_file)
+        
+        results[preset.preset_id] = cache_file
+    
+    return results
+
+
+def create_default_presets() -> list[ScenarioPreset]:
+    """Create default scenario presets for gold hedging research."""
+    return [
+        ScenarioPreset(
+            preset_id="gld-2020-covid-crash",
+            display_name="GLD March 2020 COVID Crash",
+            symbol="GLD",
+            dataset="XNAS.BASIC",
+            window_start=date(2020, 2, 15),
+            window_end=date(2020, 4, 15),
+            default_start_price=143.0,  # Approx GLD close on 2020-02-15
+            default_templates=("protective-put-atm-12m", "protective-put-95pct-12m"),
+            event_type="crash",
+            tags=("covid", "crash", "high-vol"),
+            description="March 2020 COVID market crash - extreme volatility event",
+        ),
+        ScenarioPreset(
+            preset_id="gld-2022-rate-hike-cycle",
+            display_name="GLD 2022 Rate Hike Cycle",
+            symbol="GLD",
+            dataset="XNAS.BASIC",
+            window_start=date(2022, 1, 1),
+            window_end=date(2022, 12, 31),
+            default_start_price=168.0,
+            default_templates=("protective-put-atm-12m", "ladder-50-50-atm-95pct-12m"),
+            event_type="rate_cycle",
+            tags=("rates", "fed", "extended"),
+            description="Full year 2022 - aggressive Fed rate hikes",
+        ),
+        ScenarioPreset(
+            preset_id="gcf-2024-rally",
+            display_name="GC=F 2024 Gold Rally",
+            symbol="GC",
+            dataset="GLBX.MDP3",
+            window_start=date(2024, 1, 1),
+            window_end=date(2024, 12, 31),
+            default_start_price=2060.0,
+            default_templates=("protective-put-atm-12m",),
+            event_type="rally",
+            tags=("gold", "futures", "rally"),
+            description="Gold futures rally in 2024",
+        ),
+    ]
+```
+
+### Phase 6: Settings Persistence (DATA-DB-006)
+
+**File:** `app/models/backtest_settings_repository.py`
+
+```python
+from dataclasses import asdict
+from datetime import date
+from pathlib import Path
+from uuid import UUID, uuid4
+import json
+
+from app.models.backtest_settings import BacktestSettings
+
+
+class BacktestSettingsRepository:
+    """Persistence for backtest settings."""
+    
+    def __init__(self, base_path: Path | None = None) -> None:
+        self.base_path = base_path or Path(".workspaces")
+    
+    def _settings_path(self, workspace_id: str) -> Path:
+        return self.base_path / workspace_id / "backtest_settings.json"
+    
+    def load(self, workspace_id: str) -> BacktestSettings:
+        """Load backtest settings, creating defaults if not found."""
+        path = self._settings_path(workspace_id)
+        
+        if path.exists():
+            with open(path) as f:
+                data = json.load(f)
+            return BacktestSettings(
+                settings_id=UUID(data["settings_id"]),
+                name=data.get("name", "Default Backtest"),
+                data_source=data.get("data_source", "databento"),
+                dataset=data.get("dataset", "XNAS.BASIC"),
+                schema=data.get("schema", "ohlcv-1d"),
+                start_date=date.fromisoformat(data["start_date"]),
+                end_date=date.fromisoformat(data["end_date"]),
+                underlying_symbol=data.get("underlying_symbol", "GLD"),
+                start_price=data.get("start_price", 0.0),
+                underlying_units=data.get("underlying_units", 1000.0),
+                loan_amount=data.get("loan_amount", 0.0),
+                margin_call_ltv=data.get("margin_call_ltv", 0.75),
+                template_slugs=tuple(data.get("template_slugs", ("protective-put-atm-12m",))),
+                cache_key=data.get("cache_key", ""),
+                data_cost_usd=data.get("data_cost_usd", 0.0),
+            )
+        
+        # Return defaults
+        return BacktestSettings(
+            settings_id=uuid4(),
+            name="Default Backtest",
+        )
+    
+    def save(self, workspace_id: str, settings: BacktestSettings) -> None:
+        """Persist backtest settings."""
+        path = self._settings_path(workspace_id)
+        path.parent.mkdir(parents=True, exist_ok=True)
+        
+        data = asdict(settings)
+        data["settings_id"] = str(data["settings_id"])
+        data["start_date"] = data["start_date"].isoformat()
+        data["end_date"] = data["end_date"].isoformat()
+        data["template_slugs"] = list(data["template_slugs"])
+        data["provider_ref"] = {
+            "provider_id": settings.provider_ref.provider_id,
+            "pricing_mode": settings.provider_ref.pricing_mode,
+        }
+        
+        with open(path, "w") as f:
+            json.dump(data, f, indent=2)
+```
+
+## Roadmap Items
+
+### DATA-DB-001: Databento Historical Price Source
+**Dependencies:** None  
+**Estimated effort:** 2-3 days  
+**Deliverables:**
+- `app/services/backtesting/databento_source.py`
+- `tests/test_databento_source.py` (mocked API)
+- Environment variable `DATABENTO_API_KEY` support
+
+### DATA-DB-002: Backtest Settings Model
+**Dependencies:** None  
+**Estimated effort:** 1 day  
+**Deliverables:**
+- `app/models/backtest_settings.py`
+- Repository for persistence
+
+### DATA-DB-003: Cache Management
+**Dependencies:** DATA-DB-001  
+**Estimated effort:** 1 day  
+**Deliverables:**
+- `app/services/backtesting/databento_cache.py`
+- Cache cleanup CLI command
+
+### DATA-DB-004: Backtest Page UI Updates
+**Dependencies:** DATA-DB-001, DATA-DB-002  
+**Estimated effort:** 2 days  
+**Deliverables:**
+- Updated `app/pages/backtests.py`
+- Updated `app/pages/event_comparison.py`
+- Cost estimation display
+
+### DATA-DB-005: Scenario Pre-Seeding
+**Dependencies:** DATA-DB-001  
+**Estimated effort:** 1-2 days  
+**Deliverables:**
+- `app/services/backtesting/scenario_bulk_download.py`
+- Pre-configured presets for gold hedging research
+- Bulk download script
+
+### DATA-DB-006: Options Data Source (Future)
+**Dependencies:** DATA-DB-001  
+**Estimated effort:** 3-5 days  
+**Deliverables:**
+- `DatabentoOptionSnapshotSource` implementing `OptionSnapshotSource`
+- OPRA.PILLAR integration for historical options chains
+
+## Configuration
+
+Add to `.env`:
+```
+DATABENTO_API_KEY=db-xxxxxxxxxxxxxxxxxxxxxxxx
+```
+
+Add to `requirements.txt`:
+```
+databento>=0.30.0
+```
+
+Add to `pyproject.toml`:
+```toml
+[project.optional-dependencies]
+databento = ["databento>=0.30.0"]
+```
+
+## Testing Strategy
+
+1. **Unit tests** with mocked Databento responses (`tests/test_databento_source.py`)
+2. **Integration tests** with recorded VCR cassettes (`tests/cassettes/*.yaml`)
+3. **E2E tests** using cached data (`tests/test_backtest_databento_playwright.py`)
+
+## Cost Management
+
+- Use `metadata.get_cost()` before fetching to show estimated cost
+- Default to cached data when available
+- Batch download for large historical ranges (>1 year)
+- Consider Databento flat rate plans for heavy usage
+
+## Security Considerations
+
+- API key stored in environment variable, never in code
+- Cache files contain only market data (no PII)
+- Rate limiting respected (100 requests/second per IP)
\ No newline at end of file
diff --git a/docs/roadmap/ROADMAP.yaml b/docs/roadmap/ROADMAP.yaml
index 12a041b..7e3d817 100644
--- a/docs/roadmap/ROADMAP.yaml
+++ b/docs/roadmap/ROADMAP.yaml
@@ -1,5 +1,5 @@
 version: 1
-updated_at: 2026-03-27
+updated_at: 2026-03-28
 structure:
   backlog_dir: docs/roadmap/backlog
   in_progress_dir: docs/roadmap/in-progress
@@ -13,14 +13,20 @@ notes:
   - Pre-alpha policy: we may cut or replace old features without backward compatibility until alpha is declared.
   - Alpha migration policy: once alpha is declared, compatibility only needs to move forward; backward migrations are not required.
 priority_queue:
+  - DATA-DB-001
+  - DATA-DB-002
+  - DATA-DB-004
   - CONV-001
   - EXEC-002
+  - DATA-DB-003
+  - DATA-DB-005
   - DATA-002A
   - DATA-001A
   - OPS-001
   - BT-003
   - BT-002A
   - GCF-001
+  - DATA-DB-006
 recently_completed:
   - PORTFOLIO-003
   - PORTFOLIO-002
@@ -44,6 +50,12 @@ recently_completed:
   - CORE-002B
 states:
   backlog:
+    - DATA-DB-001
+    - DATA-DB-002
+    - DATA-DB-003
+    - DATA-DB-004
+    - DATA-DB-005
+    - DATA-DB-006
     - CONV-001
     - EXEC-002
     - DATA-002A
diff --git a/docs/roadmap/backlog/DATA-DB-001-databento-historical-price-source.yaml b/docs/roadmap/backlog/DATA-DB-001-databento-historical-price-source.yaml
new file mode 100644
index 0000000..d10b3ae
--- /dev/null
+++ b/docs/roadmap/backlog/DATA-DB-001-databento-historical-price-source.yaml
@@ -0,0 +1,34 @@
+id: DATA-DB-001
+title: Databento Historical Price Source
+status: backlog
+priority: high
+dependencies: []
+estimated_effort: 2-3 days
+created: 2026-03-28
+updated: 2026-03-28
+
+description: |
+  Integrate Databento historical API as a data source for backtesting and scenario
+  comparison pages. This replaces yfinance for historical data on backtest pages
+  and provides reliable, high-quality market data.
+
+acceptance_criteria:
+  - DatabentoHistoricalPriceSource implements HistoricalPriceSource protocol
+  - Cache layer prevents redundant downloads when parameters unchanged
+  - Environment variable DATABENTO_API_KEY used for authentication
+  - Cost estimation available before data fetch
+  - GLD symbol resolved to XNAS.BASIC dataset
+  - GC=F symbol resolved to GLBX.MDP3 dataset
+  - Unit tests with mocked Databento responses pass
+
+implementation_notes: |
+  Key files:
+  - app/services/backtesting/databento_source.py (new)
+  - tests/test_databento_source.py (new)
+  
+  Uses ohlcv-1d schema for daily bars. The cache key includes dataset, symbol,
+  schema, start_date, and end_date. Cache files are Parquet format for fast
+  loading. Metadata includes download_date for age validation.
+
+dependencies_detail:
+  - None - this is the foundation for Databento integration
\ No newline at end of file
diff --git a/docs/roadmap/backlog/DATA-DB-002-backtest-settings-model.yaml b/docs/roadmap/backlog/DATA-DB-002-backtest-settings-model.yaml
new file mode 100644
index 0000000..d2edefc
--- /dev/null
+++ b/docs/roadmap/backlog/DATA-DB-002-backtest-settings-model.yaml
@@ -0,0 +1,39 @@
+id: DATA-DB-002
+title: Backtest Settings Model
+status: backlog
+priority: high
+dependencies:
+  - DATA-DB-001
+estimated_effort: 1 day
+created: 2026-03-28
+updated: 2026-03-28
+
+description: |
+  Create BacktestSettings model that captures user-configurable backtest parameters
+  independent of portfolio settings. This allows running scenarios with custom start
+  prices and position sizes without modifying the main portfolio.
+
+acceptance_criteria:
+  - BacktestSettings dataclass defined with all necessary fields
+  - start_price can be 0 (auto-derive) or explicit value
+  - underlying_units independent of portfolio.gold_ounces
+  - loan_amount and margin_call_ltv for LTV analysis
+  - data_source field supports "databento" and "yfinance"
+  - Repository persists settings per workspace
+  - Default settings created for new workspaces
+
+implementation_notes: |
+  Key fields:
+  - settings_id: UUID for tracking
+  - data_source: "databento" | "yfinance" | "synthetic"
+  - dataset: "XNAS.BASIC" | "GLBX.MDP3"
+  - underlying_symbol: "GLD" | "GC" | "XAU"
+  - start_date, end_date: date range
+  - start_price: 0 for auto-derive, or explicit
+  - underlying_units: position size for scenario
+  - loan_amount: debt level for LTV analysis
+  
+  Settings are stored in .workspaces/{workspace_id}/backtest_settings.json
+
+dependencies_detail:
+  - DATA-DB-001: Need data source configuration fields
\ No newline at end of file
diff --git a/docs/roadmap/backlog/DATA-DB-003-databento-cache-management.yaml b/docs/roadmap/backlog/DATA-DB-003-databento-cache-management.yaml
new file mode 100644
index 0000000..c5e18a3
--- /dev/null
+++ b/docs/roadmap/backlog/DATA-DB-003-databento-cache-management.yaml
@@ -0,0 +1,40 @@
+id: DATA-DB-003
+title: Databento Cache Management
+status: backlog
+priority: medium
+dependencies:
+  - DATA-DB-001
+estimated_effort: 1 day
+created: 2026-03-28
+updated: 2026-03-28
+
+description: |
+  Implement cache lifecycle management for Databento data. Cache files should be
+  invalidated after configurable age (default 30 days) and when request parameters
+  change. Provide CLI tool for cache inspection and cleanup.
+
+acceptance_criteria:
+  - DatabentoCacheManager lists all cached entries
+  - Entries invalidated after max_age_days
+  - Parameters change detection triggers re-download
+  - Cache size tracking available
+  - CLI command to clear all cache
+  - CLI command to show cache statistics
+
+implementation_notes: |
+  Cache files stored in .cache/databento/:
+  - dbn_{hash}.parquet: Data file
+  - dbn_{hash}_meta.json: Metadata (download_date, params, rows)
+  
+  Cache invalidation rules:
+  1. Age > 30 days: re-download
+  2. Parameters changed: re-download
+  3. File corruption: re-download
+  
+  CLI commands:
+  - vault-dash cache list
+  - vault-dash cache clear
+  - vault-dash cache stats
+
+dependencies_detail:
+  - DATA-DB-001: Needs DatabentoCacheKey structure
\ No newline at end of file
diff --git a/docs/roadmap/backlog/DATA-DB-004-backtest-page-ui-updates.yaml b/docs/roadmap/backlog/DATA-DB-004-backtest-page-ui-updates.yaml
new file mode 100644
index 0000000..cd6bac3
--- /dev/null
+++ b/docs/roadmap/backlog/DATA-DB-004-backtest-page-ui-updates.yaml
@@ -0,0 +1,50 @@
+id: DATA-DB-004
+title: Backtest Page UI Updates
+status: backlog
+priority: high
+dependencies:
+  - DATA-DB-001
+  - DATA-DB-002
+estimated_effort: 2 days
+created: 2026-03-28
+updated: 2026-03-28
+
+description: |
+  Update backtest and event comparison pages to support Databento data source
+  and independent scenario configuration. Show estimated data cost and cache
+  status in the UI.
+
+acceptance_criteria:
+  - Data source selector shows Databento and yFinance options
+  - Databento config shows dataset and resolution dropdowns
+  - Dataset selection updates cost estimate display
+  - Cache status shows age of cached data
+  - Independent start price input (0 = auto-derive)
+  - Independent underlying units and loan amount
+  - Event comparison page uses same data source config
+  - Settings persist across sessions
+
+implementation_notes: |
+  Page changes:
+  
+  Backtests page:
+  - Add "Data Source" section with Databento/yFinance toggle
+  - Add dataset selector (XNAS.BASIC for GLD, GLBX.MDP3 for GC=F)
+  - Add resolution selector (ohlcv-1d, ohlcv-1h)
+  - Show estimated cost with refresh button
+  - Show cache status (age, size)
+  - "Configure Scenario" section with independent start price/units
+  
+  Event comparison page:
+  - Same data source configuration
+  - Preset scenarios show if data cached
+  - Cost estimate for missing data
+  
+  State management:
+  - Use workspace-level BacktestSettings
+  - Load on page mount, save on change
+  - Invalidate cache when params change
+
+dependencies_detail:
+  - DATA-DB-001: Need DatabentoHistoricalPriceSource
+  - DATA-DB-002: Need BacktestSettings model
\ No newline at end of file
diff --git a/docs/roadmap/backlog/DATA-DB-005-scenario-pre-seeding.yaml b/docs/roadmap/backlog/DATA-DB-005-scenario-pre-seeding.yaml
new file mode 100644
index 0000000..19728fb
--- /dev/null
+++ b/docs/roadmap/backlog/DATA-DB-005-scenario-pre-seeding.yaml
@@ -0,0 +1,48 @@
+id: DATA-DB-005
+title: Scenario Pre-Seeding from Bulk Downloads
+status: backlog
+priority: medium
+dependencies:
+  - DATA-DB-001
+estimated_effort: 1-2 days
+created: 2026-03-28
+updated: 2026-03-28
+
+description: |
+  Create pre-configured scenario presets for gold hedging research and implement
+  bulk download capability to pre-seed event comparison pages. This allows quick
+  testing against historical events without per-event data fetching.
+
+acceptance_criteria:
+  - Default presets include COVID crash, rate hike cycle, gold rally events
+  - Bulk download script fetches all preset data
+  - Presets stored in config file (JSON/YAML)
+  - Event comparison page shows preset data availability
+  - One-click "Download All Presets" button
+  - Progress indicator during bulk download
+
+implementation_notes: |
+  Default presets:
+  - GLD March 2020 COVID Crash (extreme volatility)
+  - GLD 2022 Rate Hike Cycle (full year)
+  - GC=F 2024 Gold Rally (futures data)
+  
+  Bulk download flow:
+  1. Create batch job for each preset
+  2. Show progress per preset
+  3. Store in cache directory
+  4. Update preset availability status
+  
+  Preset format:
+  - preset_id: unique identifier
+  - display_name: human-readable name
+  - symbol: GLD, GC, etc.
+  - dataset: Databento dataset
+  - window_start/end: date range
+  - default_start_price: first close
+  - default_templates: hedging strategies
+  - event_type: crash, rally, rate_cycle
+  - tags: for filtering
+
+dependencies_detail:
+  - DATA-DB-001: Needs cache infrastructure
\ No newline at end of file
diff --git a/docs/roadmap/backlog/DATA-DB-006-databento-options-source.yaml b/docs/roadmap/backlog/DATA-DB-006-databento-options-source.yaml
new file mode 100644
index 0000000..196acbe
--- /dev/null
+++ b/docs/roadmap/backlog/DATA-DB-006-databento-options-source.yaml
@@ -0,0 +1,46 @@
+id: DATA-DB-006
+title: Databento Options Data Source
+status: backlog
+priority: low
+dependencies:
+  - DATA-DB-001
+estimated_effort: 3-5 days
+created: 2026-03-28
+updated: 2026-03-28
+
+description: |
+  Implement historical options data source using Databento's OPRA.PILLAR dataset.
+  This enables historical options chain lookups for accurate backtesting with
+  real options prices, replacing synthetic Black-Scholes pricing.
+
+acceptance_criteria:
+  - DatabentoOptionSnapshotSource implements OptionSnapshotSource protocol
+  - OPRA.PILLAR dataset used for GLD/SPY options
+  - Option chain lookup by snapshot_date and symbol
+  - Strike and expiry filtering supported
+  - Cached per-date for efficiency
+  - Fallback to synthetic pricing when data unavailable
+
+implementation_notes: |
+  OPRA.PILLAR provides consolidated options data from all US options exchanges.
+  
+  Key challenges:
+  1. OPRA data volume is large - need efficient caching
+  2. Option symbology differs from regular symbols
+  3. Need strike/expiry resolution in symbology
+  
+  Implementation approach:
+  - Use 'definition' schema to get instrument metadata
+  - Use 'trades' or 'ohlcv-1d' for price history
+  - Cache per (symbol, expiration, strike, option_type, date)
+  - Use continuous contracts for futures options (GC=F)
+  
+  Symbology:
+  - GLD options: Use underlying symbol "GLD" with OPRA
+  - GC options: Use parent symbology "GC" for continuous contracts
+  
+  This is a future enhancement - not required for initial backtesting
+  which uses synthetic Black-Scholes pricing.
+
+dependencies_detail:
+  - DATA-DB-001: Needs base cache infrastructure
\ No newline at end of file