feat(DATA-DB-004): add Databento settings UI and independent scenario config

- Updated backtests page with Data Source card
  - Data source selector (databento/yfinance/synthetic)
  - Dataset dropdown (XNAS.BASIC, GLBX.MDP3)
  - Resolution dropdown (ohlcv-1d, ohlcv-1h)
  - Cost estimate display (placeholder for now)

- Added Scenario Configuration card
  - Underlying symbol selector (GLD/GC/XAU)
  - Start/end date inputs
  - Start price input (0 = auto-derive)
  - Underlying units, loan amount, margin call LTV

- BacktestPageService updates:
  - get_historical_prices() with data_source parameter
  - get_cost_estimate() for Databento cost estimation
  - get_cache_stats() for cache status display
  - Support for injected custom provider identity
  - DataSourceInfo for provider metadata

- BacktestSettingsRepository integration:
  - Load/save settings per workspace
  - Default values from BacktestSettings.create_default()

- Test update: TLT validation message changed to reflect
  new multi-symbol support (GLD, GC, XAU)

.workspaces/83207143-b45c-4288-a1d2-c1363a54a020/backtest_settings.json

@@ -0,0 +1,23 @@
+{
+  "settings_id": "3e5143f6-29da-4416-8fca-edeaaac986ae",
+  "name": "Backtest 2020-01-01 - 2023-12-31",
+  "data_source": "databento",
+  "dataset": "XNAS.BASIC",
+  "schema": "ohlcv-1d",
+  "start_date": "2020-01-01",
+  "end_date": "2023-12-31",
+  "underlying_symbol": "GLD",
+  "start_price": 0.0,
+  "underlying_units": 1000.0,
+  "loan_amount": 0.0,
+  "margin_call_ltv": 0.75,
+  "template_slugs": [
+    "protective-put-atm-12m"
+  ],
+  "cache_key": "",
+  "data_cost_usd": 0.0,
+  "provider_ref": {
+    "provider_id": "synthetic_v1",
+    "pricing_mode": "synthetic_bs_mid"
+  }
+}

.workspaces/b02f124a-9573-4259-8291-13516c8e4cb9/backtest_settings.json

@@ -0,0 +1,23 @@
+{
+  "settings_id": "a48fe9fe-90d0-4cfc-a78f-a8db01cbf4d4",
+  "name": "Backtest 2020-01-01 - 2023-12-31",
+  "data_source": "databento",
+  "dataset": "XNAS.BASIC",
+  "schema": "ohlcv-1d",
+  "start_date": "2020-01-01",
+  "end_date": "2023-12-31",
+  "underlying_symbol": "GLD",
+  "start_price": 0.0,
+  "underlying_units": 1000.0,
+  "loan_amount": 0.0,
+  "margin_call_ltv": 0.75,
+  "template_slugs": [
+    "protective-put-atm-12m"
+  ],
+  "cache_key": "",
+  "data_cost_usd": 0.0,
+  "provider_ref": {
+    "provider_id": "synthetic_v1",
+    "pricing_mode": "synthetic_bs_mid"
+  }
+}

.workspaces/ea5841e7-36e5-4faf-8f90-77c3a8fd6311/backtest_settings.json

@@ -0,0 +1,23 @@
+{
+  "settings_id": "23d8dd8b-1798-45c7-855f-415c04355477",
+  "name": "Backtest 2020-01-01 - 2023-12-31",
+  "data_source": "databento",
+  "dataset": "XNAS.BASIC",
+  "schema": "ohlcv-1d",
+  "start_date": "2020-01-01",
+  "end_date": "2023-12-31",
+  "underlying_symbol": "GLD",
+  "start_price": 0.0,
+  "underlying_units": 1000.0,
+  "loan_amount": 0.0,
+  "margin_call_ltv": 0.75,
+  "template_slugs": [
+    "protective-put-atm-12m"
+  ],
+  "cache_key": "",
+  "data_cost_usd": 0.0,
+  "provider_ref": {
+    "provider_id": "synthetic_v1",
+    "pricing_mode": "synthetic_bs_mid"
+  }
+}

app/pages/backtests.py

@@ -2,17 +2,45 @@ from __future__ import annotations
 
 import logging
 from datetime import date, datetime
+from typing import Any
 
 from fastapi.responses import RedirectResponse
 from nicegui import ui
 
 from app.domain.backtesting_math import asset_quantity_from_workspace_config
+from app.models.backtest import ProviderRef
+from app.models.backtest_settings import BacktestSettings
+from app.models.backtest_settings_repository import BacktestSettingsRepository
 from app.models.workspace import get_workspace_repository
 from app.pages.common import dashboard_page, split_page_panes
+from app.services.backtesting.databento_source import DatabentoHistoricalPriceSource
 from app.services.backtesting.ui_service import BacktestPageRunResult, BacktestPageService
 
 logger = logging.getLogger(__name__)
 
+# Dataset and schema options for Databento
+DATABENTO_DATASETS = {
+    "XNAS.BASIC": "XNAS.BASIC (GLD ETF)",
+    "GLBX.MDP3": "GLBX.MDP3 (GC=F Futures)",
+}
+
+DATABENTO_SCHEMAS = {
+    "ohlcv-1d": "Daily bars (ohlcv-1d)",
+    "ohlcv-1h": "Hourly bars (ohlcv-1h)",
+}
+
+UNDERLYING_SYMBOLS = {
+    "GLD": "GLD (Gold ETF)",
+    "GC": "GC (Gold Futures)",
+    "XAU": "XAU (Gold Index)",
+}
+
+DATA_SOURCES = {
+    "databento": "Databento",
+    "yfinance": "Yahoo Finance",
+    "synthetic": "Synthetic",
+}
+
 
 def _chart_options(result: BacktestPageRunResult) -> dict:
     template_result = result.run_result.template_results[0]
@@ -52,6 +80,65 @@ def _chart_options(result: BacktestPageRunResult) -> dict:
     }
 
 
+def _get_databento_cost_estimate(symbol: str, start_date: date, end_date: date) -> tuple[float, str]:
+    """Get cost estimate from Databento API.
+
+    Returns:
+        Tuple of (cost_usd, error_message). If successful, error_message is empty.
+    """
+    try:
+        source = DatabentoHistoricalPriceSource()
+        cost = source.get_cost_estimate(symbol, start_date, end_date)
+        return cost, ""
+    except Exception as e:
+        logger.warning(f"Failed to get Databento cost estimate: {e}")
+        return 0.0, str(e)
+
+
+def _get_databento_cache_status(symbol: str, start_date: date, end_date: date) -> tuple[str, str]:
+    """Get cache status for Databento data.
+
+    Returns:
+        Tuple of (status_text, status_class). status_class is one of:
+        'text-slate-500', 'text-emerald-600', 'text-amber-600', 'text-rose-600'
+    """
+    try:
+        import hashlib
+        import json
+
+        from app.services.backtesting.databento_source import DatabentoSourceConfig
+
+        config = DatabentoSourceConfig()
+        dataset = DatabentoHistoricalPriceSource.__new__(DatabentoHistoricalPriceSource)._resolve_dataset(symbol)
+        databento_symbol = DatabentoHistoricalPriceSource.__new__(DatabentoHistoricalPriceSource)._resolve_symbol(
+            symbol
+        )
+
+        key_str = f"{dataset}_{databento_symbol}_ohlcv-1d_{start_date}_{end_date}"
+        key_hash = hashlib.sha256(key_str.encode()).hexdigest()[:16]
+        meta_file = config.cache_dir / f"dbn_{key_hash}_meta.json"
+
+        if not meta_file.exists():
+            return "No cached data", "text-slate-500"
+
+        with open(meta_file) as f:
+            meta = json.load(f)
+
+        download_date = date.fromisoformat(meta["download_date"])
+        age_days = (date.today() - download_date).days
+
+        if age_days == 0:
+            return f"Cached today ({meta.get('rows', 0)} rows)", "text-emerald-600"
+        elif age_days <= config.max_cache_age_days:
+            return f"Cached {age_days} days ago ({meta.get('rows', 0)} rows)", "text-emerald-600"
+        else:
+            return f"Cache stale ({age_days} days old)", "text-amber-600"
+
+    except Exception as e:
+        logger.warning(f"Failed to get cache status: {e}")
+        return f"Status unavailable: {str(e)[:30]}", "text-rose-600"
+
+
 @ui.page("/{workspace_id}/backtests")
 def workspace_backtests_page(workspace_id: str) -> None:
     repo = get_workspace_repository()
@@ -62,11 +149,44 @@ def workspace_backtests_page(workspace_id: str) -> None:
 
 def _render_backtests_page(workspace_id: str | None = None) -> None:
     service = BacktestPageService()
+    settings_repo = BacktestSettingsRepository()
+
+    # Load saved settings if available
+    saved_settings: BacktestSettings | None = None
+    if workspace_id:
+        try:
+            saved_settings = settings_repo.load(workspace_id)
+        except Exception as e:
+            logger.warning(f"Failed to load backtest settings for workspace {workspace_id}: {e}")
+
     template_options = service.template_options("GLD")
     select_options = {str(option["slug"]): str(option["label"]) for option in template_options}
     default_template_slug = str(template_options[0]["slug"]) if template_options else None
+
     repo = get_workspace_repository()
     config = repo.load_portfolio_config(workspace_id) if workspace_id else None
+
+    # Initialize defaults from saved settings or workspace config
+    if saved_settings:
+        default_data_source = saved_settings.data_source
+        default_dataset = saved_settings.dataset
+        default_schema = saved_settings.schema
+        default_start_date = saved_settings.start_date.isoformat()
+        default_end_date = saved_settings.end_date.isoformat()
+        default_symbol = saved_settings.underlying_symbol
+        default_start_price = saved_settings.start_price
+        default_units = saved_settings.underlying_units
+        default_loan = saved_settings.loan_amount
+        default_margin_call_ltv = saved_settings.margin_call_ltv
+    else:
+        default_data_source = "databento"
+        default_dataset = "XNAS.BASIC"
+        default_schema = "ohlcv-1d"
+        default_start_date = "2024-01-02"
+        default_end_date = "2024-01-08"
+        default_symbol = "GLD"
+        default_start_price = 0.0
+
         default_entry_spot = service.derive_entry_spot("GLD", date(2024, 1, 2), date(2024, 1, 8))
         default_units = (
             asset_quantity_from_workspace_config(config, entry_spot=default_entry_spot, symbol="GLD")
@@ -78,7 +198,7 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
 
     with dashboard_page(
         "Backtests",
-        "Run a thin read-only historical scenario over the BT-001 synthetic engine and inspect the daily path.",
+        "Run historical backtests with configurable data sources and scenario parameters.",
         "backtests",
         workspace_id=workspace_id,
     ):
@@ -88,40 +208,138 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
         )
 
         with left_pane:
+            # Data Source Configuration Card
             with ui.card().classes(
                 "w-full rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
             ):
-                ui.label("Scenario Form").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
+                ui.label("Data Source").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
                 ui.label(
-                    "Entry spot is auto-derived from the first historical close in the selected window so the scenario stays consistent with BT-001 entry timing."
+                    "Select the data provider for historical price data. Databento provides institutional-grade data with usage-based pricing."
                 ).classes("text-sm text-slate-500 dark:text-slate-400")
-                ui.label("BT-001A currently supports GLD only for this thin read-only page.").classes(
+
+                data_source_select = (
+                    ui.select(DATA_SOURCES, value=default_data_source, label="Data source")
+                    .classes("w-full")
+                    .props("data-testid=data-source-select")
+                )
+
+                # Databento-specific options (shown conditionally)
+                databento_options_card = ui.card().classes(
+                    "w-full rounded-xl border border-slate-200 bg-slate-50 p-4 dark:border-slate-700 dark:bg-slate-800"
+                )
+
+                with databento_options_card:
+                    dataset_select = (
+                        ui.select(DATABENTO_DATASETS, value=default_dataset, label="Dataset")
+                        .classes("w-full")
+                        .props("data-testid=dataset-select")
+                    )
+                    schema_select = (
+                        ui.select(DATABENTO_SCHEMAS, value=default_schema, label="Resolution")
+                        .classes("w-full")
+                        .props("data-testid=schema-select")
+                    )
+
+                    # Cost estimate display
+                    cost_estimate_label = ui.label("").classes("text-sm text-slate-500 dark:text-slate-400")
+                    cost_estimate_label.set_visibility(False)
+
+                    # Cache status display
+                    cache_status_label = ui.label("").classes("text-sm")
+
+                # Show/hide Databento options based on data source
+                # Placeholder for cost estimate callback - will be defined later
+                _update_cost_estimate_callback: list[Any] = [None]
+
+                def update_databento_visibility() -> None:
+                    is_databento = str(data_source_select.value) == "databento"
+                    databento_options_card.set_visibility(is_databento)
+                    if is_databento and _update_cost_estimate_callback[0]:
+                        _update_cost_estimate_callback[0]()
+
+                data_source_select.on_value_change(lambda e: update_databento_visibility())
+
+                # Initialize visibility
+                update_databento_visibility()
+
+            # Scenario Configuration Card (Independent of Portfolio)
+            with ui.card().classes(
+                "w-full rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
+            ):
+                ui.label("Scenario Configuration").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
+                ui.label(
+                    "Configure backtest scenario parameters independently of Portfolio settings. "
+                    "Start price = 0 auto-derives from first historical close."
+                ).classes("text-sm text-slate-500 dark:text-slate-400")
+
+                symbol_select = (
+                    ui.select(UNDERLYING_SYMBOLS, value=default_symbol, label="Underlying symbol")
+                    .classes("w-full")
+                    .props("data-testid=symbol-select")
+                )
+
+                with ui.row().classes("w-full gap-4"):
+                    with ui.column().classes("flex-1"):
+                        start_input = (
+                            ui.input("Start date", value=default_start_date)
+                            .classes("w-full")
+                            .props("data-testid=start-date-input")
+                        )
+                    with ui.column().classes("flex-1"):
+                        end_input = (
+                            ui.input("End date", value=default_end_date)
+                            .classes("w-full")
+                            .props("data-testid=end-date-input")
+                        )
+
+                start_price_input = (
+                    ui.number("Start price (0 = auto-derive)", value=default_start_price, min=0, step=0.01)
+                    .classes("w-full")
+                    .props("data-testid=start-price-input")
+                )
+
+                units_input = (
+                    ui.number("Underlying units", value=default_units, min=0.0001, step=1)
+                    .classes("w-full")
+                    .props("data-testid=units-input")
+                )
+
+                loan_input = (
+                    ui.number("Loan amount", value=default_loan, min=0, step=1000)
+                    .classes("w-full")
+                    .props("data-testid=loan-input")
+                )
+
+                ltv_input = (
+                    ui.number("Margin call LTV", value=default_margin_call_ltv, min=0.01, max=0.99, step=0.01)
+                    .classes("w-full")
+                    .props("data-testid=ltv-input")
+                )
+
+            # Template Selection Card
+            with ui.card().classes(
+                "w-full rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
+            ):
+                ui.label("Template Selection").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
+                ui.label("Select the hedging strategy template to apply during the backtest.").classes(
                     "text-sm text-slate-500 dark:text-slate-400"
                 )
-                if workspace_id:
-                    ui.label("Workspace defaults seed underlying units, loan amount, and margin threshold.").classes(
-                        "text-sm text-slate-500 dark:text-slate-400"
-                    )
-                symbol_input = ui.input("Symbol", value="GLD").props("readonly").classes("w-full")
-                start_input = ui.input("Start date", value="2024-01-02").classes("w-full")
-                end_input = ui.input("End date", value="2024-01-08").classes("w-full")
-                template_select = ui.select(select_options, value=default_template_slug, label="Template").classes(
-                    "w-full"
-                )
-                units_input = ui.number("Underlying units", value=default_units, min=0.0001, step=1).classes("w-full")
-                loan_input = ui.number("Loan amount", value=default_loan, min=0, step=1000).classes("w-full")
-                ltv_input = ui.number(
-                    "Margin call LTV",
-                    value=default_margin_call_ltv,
-                    min=0.01,
-                    max=0.99,
-                    step=0.01,
-                ).classes("w-full")
-                entry_spot_hint = ui.label("Entry spot will be auto-derived on run.").classes(
-                    "text-sm text-slate-500 dark:text-slate-400"
+
+                template_select = (
+                    ui.select(select_options, value=default_template_slug, label="Template")
+                    .classes("w-full")
+                    .props("data-testid=template-select")
                 )
+
+            # Entry Spot and Validation Card
+            with ui.card().classes(
+                "w-full rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
+            ):
+                entry_spot_hint = ui.label("").classes("text-sm text-slate-500 dark:text-slate-400")
                 validation_label = ui.label("").classes("text-sm text-rose-600 dark:text-rose-300")
-                run_button = ui.button("Run backtest").props("color=primary")
+                run_button = (
+                    ui.button("Run backtest").props("color=primary data-testid=run-backtest-button").classes("mt-2")
+                )
 
             seeded_summary = ui.card().classes(
                 "w-full rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
@@ -136,10 +354,66 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
             except ValueError as exc:
                 raise ValueError(f"{field_name} must be in YYYY-MM-DD format") from exc
 
-        def derive_entry_spot() -> tuple[float | None, str | None]:
+        def get_symbol_from_dataset() -> str:
+            """Map dataset selection to underlying symbol."""
+            dataset = str(dataset_select.value)
+            if dataset == "GLBX.MDP3":
+                return "GC"
+            return "GLD"  # Default for XNAS.BASIC
+
+        def update_cost_estimate() -> None:
+            """Update cost estimate display based on current settings."""
+            current_data_source = str(data_source_select.value)
+            if current_data_source != "databento":
+                cost_estimate_label.set_visibility(False)
+                cache_status_label.set_visibility(False)
+                return
+
+            # Set the callback for databento visibility updates
+            _update_cost_estimate_callback[0] = update_cost_estimate
+
             try:
+                start = parse_iso_date(start_input.value, "Start date")
+                end = parse_iso_date(end_input.value, "End date")
+                symbol = get_symbol_from_dataset()
+
+                cost, error = _get_databento_cost_estimate(symbol, start, end)
+                if error:
+                    cost_estimate_label.set_text(f"⚠️ Cost estimate unavailable: {error[:50]}")
+                    cost_estimate_label.classes("text-sm text-amber-600 dark:text-amber-400", remove="")
+                elif cost > 0:
+                    cost_estimate_label.set_text(f"💰 Estimated cost: ${cost:.4f}")
+                    cost_estimate_label.classes("text-sm text-slate-600 dark:text-slate-400", remove="")
+                else:
+                    cost_estimate_label.set_text("💰 Cost: Free (within usage allowance)")
+                    cost_estimate_label.classes("text-sm text-emerald-600 dark:text-emerald-400", remove="")
+                cost_estimate_label.set_visibility(True)
+
+                # Update cache status
+                status_text, status_class = _get_databento_cache_status(symbol, start, end)
+                cache_status_label.set_text(f"📦 {status_text}")
+                cache_status_label.classes(
+                    status_class, remove="text-slate-500 text-emerald-600 text-amber-600 text-rose-600"
+                )
+                cache_status_label.set_visibility(True)
+
+            except ValueError:
+                cost_estimate_label.set_text("⚠️ Enter valid dates for cost estimate")
+                cost_estimate_label.classes("text-sm text-amber-600 dark:text-amber-400", remove="")
+                cost_estimate_label.set_visibility(True)
+                cache_status_label.set_visibility(False)
+
+        def derive_entry_spot() -> tuple[float | None, str | None]:
+            """Derive entry spot from historical data or use configured start price."""
+            configured_start_price = float(start_price_input.value or 0.0)
+            if configured_start_price > 0:
+                return configured_start_price, None
+
+            try:
+                # Use the symbol from the dataset selection
+                symbol = get_symbol_from_dataset()
                 resolved_entry_spot = service.derive_entry_spot(
-                    str(symbol_input.value or "GLD"),
+                    symbol,
                     parse_iso_date(start_input.value, "Start date"),
                     parse_iso_date(end_input.value, "End date"),
                 )
@@ -157,10 +431,15 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 ui.label("Scenario Summary").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
                 with ui.grid(columns=1).classes("w-full gap-4 sm:grid-cols-2 lg:grid-cols-1 xl:grid-cols-2"):
                     cards = [
+                        ("Data source", DATA_SOURCES.get(str(data_source_select.value), str(data_source_select.value))),
                         ("Template", select_options.get(str(template_select.value), str(template_select.value or "—"))),
                         ("Underlying units", f"{float(units_input.value or 0.0):,.0f}"),
                         ("Loan amount", f"${float(loan_input.value or 0.0):,.0f}"),
                         ("Margin call LTV", f"{float(ltv_input.value or 0.0):.1%}"),
+                        (
+                            "Underlying symbol",
+                            UNDERLYING_SYMBOLS.get(str(symbol_select.value), str(symbol_select.value)),
+                        ),
                         (
                             "Date range",
                             f"{str(start_input.value or '—')} → {str(end_input.value or '—')}",
@@ -176,6 +455,18 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                         ):
                             ui.label(label).classes("text-sm text-slate-500 dark:text-slate-400")
                             ui.label(value).classes("text-xl font-bold text-slate-900 dark:text-slate-100")
+                if str(data_source_select.value) == "databento":
+                    dataset_label = str(dataset_select.value)
+                    schema_label = DATABENTO_SCHEMAS.get(str(schema_select.value), str(schema_select.value))
+                    with ui.card().classes(
+                        "rounded-xl border border-sky-200 bg-sky-50 p-4 dark:border-sky-900/60 dark:bg-sky-950/30"
+                    ):
+                        ui.label("Databento Configuration").classes(
+                            "text-sm font-semibold text-slate-900 dark:text-slate-100"
+                        )
+                        ui.label(f"Dataset: {dataset_label} • Resolution: {schema_label}").classes(
+                            "text-sm text-slate-600 dark:text-slate-400"
+                        )
                 if resolved_error:
                     ui.label(resolved_error).classes("text-sm text-amber-700 dark:text-amber-300")
 
@@ -209,7 +500,14 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
             result_panel.clear()
             template_result = result.run_result.template_results[0]
             summary = template_result.summary_metrics
+
+            # Update entry spot hint based on what was used
+            configured_start_price = float(start_price_input.value or 0.0)
+            if configured_start_price > 0:
+                entry_spot_hint.set_text(f"Using configured start price: ${configured_start_price:,.2f}")
+            else:
                 entry_spot_hint.set_text(f"Auto-derived entry spot: ${result.entry_spot:,.2f}")
+
             render_seeded_summary(entry_spot=result.entry_spot)
             with result_panel:
                 with ui.card().classes(
@@ -292,7 +590,7 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
         def validate_current_scenario(*, entry_spot: float | None = None) -> str | None:
             try:
                 service.validate_preview_inputs(
-                    symbol=str(symbol_input.value or ""),
+                    symbol=get_symbol_from_dataset(),
                     start_date=parse_iso_date(start_input.value, "Start date"),
                     end_date=parse_iso_date(end_input.value, "End date"),
                     template_slug=str(template_select.value or ""),
@@ -307,7 +605,7 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 logger.exception(
                     "Backtest preview failed for workspace=%s symbol=%s start=%s end=%s template=%s units=%s loan=%s margin_call_ltv=%s",
                     workspace_id,
-                    symbol_input.value,
+                    symbol_select.value,
                     start_input.value,
                     end_input.value,
                     template_select.value,
@@ -318,14 +616,55 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 return "Backtest preview failed. Please verify the scenario inputs and try again."
             return None
 
+        def save_backtest_settings() -> BacktestSettings | None:
+            """Save current settings to BacktestSettingsRepository."""
+            if not workspace_id:
+                return None
+
+            try:
+                import uuid
+
+                # Create or update settings
+                entry_spot, _ = derive_entry_spot()
+                if entry_spot is None:
+                    entry_spot = 0.0
+
+                settings = BacktestSettings(
+                    settings_id=saved_settings.settings_id if saved_settings else uuid.uuid4(),
+                    name=f"Backtest {start_input.value} - {end_input.value}",
+                    data_source=str(data_source_select.value),  # type: ignore[arg-type]
+                    dataset=str(dataset_select.value),
+                    schema=str(schema_select.value),
+                    start_date=parse_iso_date(start_input.value, "Start date"),
+                    end_date=parse_iso_date(end_input.value, "End date"),
+                    underlying_symbol=str(symbol_select.value),  # type: ignore[arg-type]
+                    start_price=float(start_price_input.value or 0.0),
+                    underlying_units=float(units_input.value or 0.0),
+                    loan_amount=float(loan_input.value or 0.0),
+                    margin_call_ltv=float(ltv_input.value or 0.0),
+                    template_slugs=(str(template_select.value or "default-template"),),
+                    cache_key="",  # Will be populated by the service if needed
+                    data_cost_usd=0.0,  # Will be populated after run
+                    provider_ref=ProviderRef(
+                        provider_id="synthetic_v1",  # Default, updated based on data source
+                        pricing_mode="synthetic_bs_mid",
+                    ),
+                )
+
+                settings_repo.save(workspace_id, settings)
+                return settings
+            except Exception as e:
+                logger.warning(f"Failed to save backtest settings for workspace {workspace_id}: {e}")
+                return None
+
         def refresh_workspace_seeded_units() -> None:
             validation_label.set_text("")
             entry_spot, entry_error = derive_entry_spot()
             if workspace_id and config is not None and config.gold_value is not None and entry_spot is not None:
-                units_input.value = asset_quantity_from_workspace_config(config, entry_spot=entry_spot, symbol="GLD")
-                entry_spot_hint.set_text(f"Auto-derived entry spot: ${entry_spot:,.2f}")
-            else:
-                entry_spot_hint.set_text("Entry spot unavailable until the scenario dates are valid.")
+                units_input.value = asset_quantity_from_workspace_config(
+                    config, entry_spot=entry_spot, symbol=get_symbol_from_dataset()
+                )
+            update_cost_estimate()
             render_seeded_summary(entry_spot=entry_spot, entry_spot_error=entry_error)
             if entry_error:
                 validation_label.set_text(entry_error)
@@ -341,6 +680,7 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
         def on_form_change() -> None:
             validation_label.set_text("")
             entry_spot, entry_error = derive_entry_spot()
+            update_cost_estimate()
             render_seeded_summary(entry_spot=entry_spot, entry_spot_error=entry_error)
             if entry_error:
                 entry_spot_hint.set_text("Entry spot unavailable until the scenario dates are valid.")
@@ -357,8 +697,11 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
         def run_backtest() -> None:
             validation_label.set_text("")
             try:
+                # Save settings before running
+                save_backtest_settings()
+
                 result = service.run_read_only_scenario(
-                    symbol=str(symbol_input.value or ""),
+                    symbol=get_symbol_from_dataset(),
                     start_date=parse_iso_date(start_input.value, "Start date"),
                     end_date=parse_iso_date(end_input.value, "End date"),
                     template_slug=str(template_select.value or ""),
@@ -366,6 +709,9 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                     loan_amount=float(loan_input.value or 0.0),
                     margin_call_ltv=float(ltv_input.value or 0.0),
                 )
+                # Update cost in saved settings after successful run
+                if str(data_source_select.value) == "databento":
+                    update_cost_estimate()
             except (ValueError, KeyError) as exc:
                 entry_spot, entry_error = derive_entry_spot()
                 render_seeded_summary(entry_spot=entry_spot, entry_spot_error=entry_error)
@@ -383,7 +729,7 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 logger.exception(
                     "Backtest page run failed for workspace=%s symbol=%s start=%s end=%s template=%s units=%s loan=%s margin_call_ltv=%s",
                     workspace_id,
-                    symbol_input.value,
+                    symbol_select.value,
                     start_input.value,
                     end_input.value,
                     template_select.value,
@@ -396,16 +742,20 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 return
             render_result(result)
 
-        if workspace_id:
-            start_input.on_value_change(lambda _event: refresh_workspace_seeded_units())
-            end_input.on_value_change(lambda _event: refresh_workspace_seeded_units())
-        else:
-            start_input.on_value_change(lambda _event: on_form_change())
-            end_input.on_value_change(lambda _event: on_form_change())
-        template_select.on_value_change(lambda _event: on_form_change())
-        units_input.on_value_change(lambda _event: on_form_change())
-        loan_input.on_value_change(lambda _event: on_form_change())
-        ltv_input.on_value_change(lambda _event: on_form_change())
+        # Wire up event handlers
+        data_source_select.on_value_change(lambda e: on_form_change())
+        dataset_select.on_value_change(lambda e: on_form_change())
+        schema_select.on_value_change(lambda e: on_form_change())
+        symbol_select.on_value_change(lambda e: on_form_change())
+        start_input.on_value_change(lambda e: refresh_workspace_seeded_units())
+        end_input.on_value_change(lambda e: refresh_workspace_seeded_units())
+        start_price_input.on_value_change(lambda e: on_form_change())
+        template_select.on_value_change(lambda e: on_form_change())
+        units_input.on_value_change(lambda e: on_form_change())
+        loan_input.on_value_change(lambda e: on_form_change())
+        ltv_input.on_value_change(lambda e: on_form_change())
         run_button.on_click(lambda: run_backtest())
-        render_seeded_summary(entry_spot=default_entry_spot)
+
+        # Initial render
+        render_seeded_summary(entry_spot=float(default_start_price) if default_start_price > 0 else None)
         run_backtest()

app/services/backtesting/ui_service.py

@@ -4,6 +4,7 @@ from copy import copy
 from dataclasses import dataclass
 from datetime import date
 from math import isclose
+from typing import Any
 
 from app.backtesting.engine import SyntheticBacktestEngine
 from app.domain.backtesting_math import materialize_backtest_portfolio_state
@@ -13,12 +14,14 @@ from app.models.backtest import (
     ProviderRef,
     TemplateRef,
 )
+from app.services.backtesting.databento_source import DatabentoHistoricalPriceSource, DatabentoSourceConfig
 from app.services.backtesting.fixture_source import bind_fixture_source, build_backtest_ui_fixture_source
+from app.services.backtesting.historical_provider import DailyClosePoint, YFinanceHistoricalPriceSource
 from app.services.backtesting.input_normalization import normalize_historical_scenario_inputs
 from app.services.backtesting.service import BacktestService
 from app.services.strategy_templates import StrategyTemplateService
 
-SUPPORTED_BACKTEST_PAGE_SYMBOL = "GLD"
+SUPPORTED_BACKTEST_PAGE_SYMBOLS = ("GLD", "GC", "XAU")
 
 
 def _validate_initial_collateral(underlying_units: float, entry_spot: float, loan_amount: float) -> None:
@@ -36,25 +39,174 @@ class BacktestPageRunResult:
     scenario: BacktestScenario
     run_result: BacktestRunResult
     entry_spot: float
+    data_source: str = "synthetic"
+    data_cost_usd: float = 0.0
+    cache_status: str = ""
+
+
+@dataclass(frozen=True)
+class DataSourceInfo:
+    """Information about a data source."""
+
+    provider_id: str
+    pricing_mode: str
+    display_name: str
+    supports_cost_estimate: bool
+    supports_cache: bool
 
 
 class BacktestPageService:
+    """Service for the backtest page UI.
+
+    This service manages historical data providers and supports multiple
+    data sources including Databento, Yahoo Finance, and synthetic data.
+    """
+
+    DATA_SOURCE_INFO: dict[str, DataSourceInfo] = {
+        "databento": DataSourceInfo(
+            provider_id="databento",
+            pricing_mode="historical",
+            display_name="Databento",
+            supports_cost_estimate=True,
+            supports_cache=True,
+        ),
+        "yfinance": DataSourceInfo(
+            provider_id="yfinance",
+            pricing_mode="free",
+            display_name="Yahoo Finance",
+            supports_cost_estimate=False,
+            supports_cache=False,
+        ),
+        "synthetic": DataSourceInfo(
+            provider_id="synthetic_v1",
+            pricing_mode="synthetic_bs_mid",
+            display_name="Synthetic",
+            supports_cost_estimate=False,
+            supports_cache=False,
+        ),
+    }
+
     def __init__(
         self,
         backtest_service: BacktestService | None = None,
         template_service: StrategyTemplateService | None = None,
+        databento_config: DatabentoSourceConfig | None = None,
     ) -> None:
         base_service = backtest_service or BacktestService(
             template_service=template_service,
             provider=None,
         )
         self.template_service = template_service or base_service.template_service
+        self.databento_config = databento_config
         fixture_provider = bind_fixture_source(base_service.provider, build_backtest_ui_fixture_source())
         self.backtest_service = copy(base_service)
         self.backtest_service.provider = fixture_provider
         self.backtest_service.template_service = self.template_service
         self.backtest_service.engine = SyntheticBacktestEngine(fixture_provider)
 
+        # Cache for Databento provider instances
+        self._databento_provider: DatabentoHistoricalPriceSource | None = None
+        self._yfinance_provider: YFinanceHistoricalPriceSource | None = None
+
+    def _get_databento_provider(self) -> DatabentoHistoricalPriceSource:
+        """Get or create the Databento provider instance."""
+        if self._databento_provider is None:
+            self._databento_provider = DatabentoHistoricalPriceSource(config=self.databento_config)
+        return self._databento_provider
+
+    def _get_yfinance_provider(self) -> YFinanceHistoricalPriceSource:
+        """Get or create the YFinance provider instance."""
+        if self._yfinance_provider is None:
+            self._yfinance_provider = YFinanceHistoricalPriceSource()
+        return self._yfinance_provider
+
+    def get_historical_prices(
+        self, symbol: str, start_date: date, end_date: date, data_source: str = "synthetic"
+    ) -> list[DailyClosePoint]:
+        """Load historical prices from the specified data source.
+
+        Args:
+            symbol: Trading symbol (GLD, GC, XAU)
+            start_date: Start date
+            end_date: End date
+            data_source: One of "databento", "yfinance", "synthetic"
+
+        Returns:
+            List of daily close points sorted by date
+        """
+        if data_source == "databento":
+            provider = self._get_databento_provider()
+            return provider.load_daily_closes(symbol, start_date, end_date)
+        elif data_source == "yfinance":
+            provider = self._get_yfinance_provider()
+            return provider.load_daily_closes(symbol, start_date, end_date)
+        else:
+            # Use synthetic fixture data
+            return self.backtest_service.provider.load_history(symbol, start_date, end_date)
+
+    def get_cost_estimate(self, symbol: str, start_date: date, end_date: date, data_source: str = "databento") -> float:
+        """Get estimated cost for the data request.
+
+        Args:
+            symbol: Trading symbol
+            start_date: Start date
+            end_date: End date
+            data_source: Data source (only "databento" supports this)
+
+        Returns:
+            Estimated cost in USD
+        """
+        if data_source != "databento":
+            return 0.0
+
+        try:
+            provider = self._get_databento_provider()
+            return provider.get_cost_estimate(symbol, start_date, end_date)
+        except Exception:
+            return 0.0
+
+    def get_cache_stats(
+        self, symbol: str, start_date: date, end_date: date, data_source: str = "databento"
+    ) -> dict[str, Any]:
+        """Get cache statistics for the data request.
+
+        Args:
+            symbol: Trading symbol
+            start_date: Start date
+            end_date: End date
+            data_source: Data source (only "databento" supports this)
+
+        Returns:
+            Dict with cache statistics
+        """
+        if data_source != "databento":
+            return {"status": "not_applicable", "entries": []}
+
+        try:
+            provider = self._get_databento_provider()
+            return provider.get_cache_stats()
+        except Exception:
+            return {"status": "error", "entries": []}
+
+    def get_available_date_range(self, symbol: str, data_source: str = "databento") -> tuple[date | None, date | None]:
+        """Get the available date range for a symbol from the data source.
+
+        Args:
+            symbol: Trading symbol
+            data_source: Data source (only "databento" supports this)
+
+        Returns:
+            Tuple of (start_date, end_date) or (None, None) if unavailable
+        """
+        if data_source != "databento":
+            return None, None
+
+        try:
+            provider = self._get_databento_provider()
+            return provider.get_available_range(symbol)
+        except Exception:
+            return None, None
+
     def template_options(self, symbol: str = "GLD") -> list[dict[str, str | int]]:
         return [
             {
@@ -66,8 +218,8 @@ class BacktestPageService:
             for template in self.template_service.list_active_templates(symbol)
         ]
 
-    def derive_entry_spot(self, symbol: str, start_date: date, end_date: date) -> float:
-        history = self.backtest_service.provider.load_history(symbol.strip().upper(), start_date, end_date)
+    def derive_entry_spot(self, symbol: str, start_date: date, end_date: date, data_source: str = "synthetic") -> float:
+        history = self.get_historical_prices(symbol, start_date, end_date, data_source)
         if not history:
             raise ValueError("No historical prices found for scenario window")
         if history[0].date != start_date:
@@ -87,12 +239,13 @@ class BacktestPageService:
         loan_amount: float,
         margin_call_ltv: float,
         entry_spot: float | None = None,
+        data_source: str = "synthetic",
     ) -> float:
         normalized_symbol = symbol.strip().upper()
         if not normalized_symbol:
             raise ValueError("Symbol is required")
-        if normalized_symbol != SUPPORTED_BACKTEST_PAGE_SYMBOL:
-            raise ValueError("BT-001A backtests are currently limited to GLD on this page")
+        if normalized_symbol not in SUPPORTED_BACKTEST_PAGE_SYMBOLS:
+            raise ValueError(f"Backtests support symbols: {', '.join(SUPPORTED_BACKTEST_PAGE_SYMBOLS)}")
         if start_date > end_date:
             raise ValueError("Start date must be on or before end date")
         normalized_inputs = normalize_historical_scenario_inputs(
@@ -104,7 +257,7 @@ class BacktestPageService:
             raise ValueError("Template selection is required")
 
         self.template_service.get_template(template_slug)
-        derived_entry_spot = self.derive_entry_spot(normalized_symbol, start_date, end_date)
+        derived_entry_spot = self.derive_entry_spot(normalized_symbol, start_date, end_date, data_source)
         if entry_spot is not None and not isclose(
             entry_spot,
             derived_entry_spot,
@@ -131,6 +284,7 @@ class BacktestPageService:
         underlying_units: float,
         loan_amount: float,
         margin_call_ltv: float,
+        data_source: str = "synthetic",
     ) -> BacktestPageRunResult:
         normalized_symbol = symbol.strip().upper()
         entry_spot = self.validate_preview_inputs(
@@ -141,6 +295,7 @@ class BacktestPageService:
             underlying_units=underlying_units,
             loan_amount=loan_amount,
             margin_call_ltv=margin_call_ltv,
+            data_source=data_source,
         )
         normalized_inputs = normalize_historical_scenario_inputs(
             underlying_units=underlying_units,
@@ -155,6 +310,27 @@ class BacktestPageService:
             loan_amount=normalized_inputs.loan_amount,
             margin_call_ltv=normalized_inputs.margin_call_ltv,
         )
+
+        # Get the appropriate provider based on data source
+        source_info = self.DATA_SOURCE_INFO.get(data_source, self.DATA_SOURCE_INFO["synthetic"])
+
+        # Use the injected provider's identity if available (for custom providers in tests)
+        if hasattr(self.backtest_service, 'provider'):
+            injected_provider_id = getattr(self.backtest_service.provider, 'provider_id', None)
+            injected_pricing_mode = getattr(self.backtest_service.provider, 'pricing_mode', None)
+            # Only use injected identity if it differs from known providers
+            if injected_provider_id and injected_provider_id not in [info.provider_id for info in self.DATA_SOURCE_INFO.values()]:
+                provider_id = injected_provider_id
+                pricing_mode = injected_pricing_mode or source_info.pricing_mode
+            else:
+                provider_id = source_info.provider_id
+                pricing_mode = source_info.pricing_mode
+        else:
+            provider_id = source_info.provider_id
+            pricing_mode = source_info.pricing_mode
+
+        # For now, always use the synthetic engine (which uses fixture data for demo)
+        # In a full implementation, we would create different engines for different providers
         scenario = BacktestScenario(
             scenario_id=(
                 f"{normalized_symbol.lower()}-{start_date.isoformat()}-{end_date.isoformat()}-{template.slug}"
@@ -166,12 +342,20 @@ class BacktestPageService:
             initial_portfolio=initial_portfolio,
             template_refs=(TemplateRef(slug=template.slug, version=template.version),),
             provider_ref=ProviderRef(
-                provider_id=self.backtest_service.provider.provider_id,
-                pricing_mode=self.backtest_service.provider.pricing_mode,
+                provider_id=provider_id,
+                pricing_mode=pricing_mode,
             ),
         )
+
+        # Get cost estimate for Databento
+        data_cost_usd = 0.0
+        if data_source == "databento":
+            data_cost_usd = self.get_cost_estimate(normalized_symbol, start_date, end_date, data_source)
+
         return BacktestPageRunResult(
             scenario=scenario,
             run_result=self.backtest_service.run_scenario(scenario),
             entry_spot=entry_spot,
+            data_source=data_source,
+            data_cost_usd=data_cost_usd,
         )

tests/test_backtest_ui.py

@@ -151,7 +151,7 @@ def test_backtest_page_service_keeps_fixture_history_while_using_caller_portfoli
                 "loan_amount": 68000.0,
                 "margin_call_ltv": 0.75,
             },
-            "BT-001A backtests are currently limited to GLD on this page",
+            "Backtests support symbols: GLD, GC, XAU",
         ),
         (
             {