feat(UX-001): add full-width two-pane dashboard layout

app/pages/backtests.py

@@ -7,7 +7,7 @@ from nicegui import ui
 
 from app.domain.backtesting_math import asset_quantity_from_workspace_config
 from app.models.workspace import get_workspace_repository
-from app.pages.common import dashboard_page, render_workspace_recovery
+from app.pages.common import dashboard_page, split_page_panes
 from app.services.backtesting.ui_service import BacktestPageRunResult, BacktestPageService
 
 
@@ -79,9 +79,14 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
         "backtests",
         workspace_id=workspace_id,
     ):
-        with ui.row().classes("w-full gap-6 max-lg:flex-col"):
+        left_pane, right_pane = split_page_panes(
+            left_testid="backtests-left-pane",
+            right_testid="backtests-right-pane",
+        )
+
+        with left_pane:
             with ui.card().classes(
-                "w-full max-w-xl rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
+                "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(
@@ -115,6 +120,11 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 validation_label = ui.label("").classes("text-sm text-rose-600 dark:text-rose-300")
                 run_button = ui.button("Run backtest").props("color=primary")
 
+            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"
+            )
+
+        with right_pane:
             result_panel = ui.column().classes("w-full gap-6")
 
         def parse_iso_date(raw: object, field_name: str) -> date:
@@ -123,16 +133,62 @@ 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 render_seeded_summary(*, entry_spot: float | None = None) -> None:
+            seeded_summary.clear()
+            resolved_entry_spot = entry_spot
+            if resolved_entry_spot is None:
+                try:
+                    resolved_entry_spot = service.derive_entry_spot(
+                        str(symbol_input.value or "GLD"),
+                        parse_iso_date(start_input.value, "Start date"),
+                        parse_iso_date(end_input.value, "End date"),
+                    )
+                except (ValueError, KeyError):
+                    resolved_entry_spot = None
+            with seeded_summary:
+                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 = [
+                        ("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"${float(loan_input.value or 0.0):,.0f}"),
+                        ("Margin call LTV", f"{float(ltv_input.value or 0.0):.1%}"),
+                        (
+                            "Date range",
+                            f"{str(start_input.value or '—')} → {str(end_input.value or '—')}",
+                        ),
+                        (
+                            "Entry spot",
+                            f"${resolved_entry_spot:,.2f}" if resolved_entry_spot is not None else "Pending",
+                        ),
+                    ]
+                    for label, value in cards:
+                        with ui.card().classes(
+                            "rounded-xl border border-slate-200 bg-slate-50 p-4 shadow-none dark:border-slate-800 dark:bg-slate-950"
+                        ):
+                            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")
+
+        def render_result_validation(message: str) -> None:
+            result_panel.clear()
+            with result_panel:
+                with ui.card().classes(
+                    "w-full rounded-2xl border border-amber-200 bg-amber-50 shadow-sm dark:border-amber-900/60 dark:bg-amber-950/30"
+                ):
+                    ui.label("Scenario Results").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
+                    ui.label(message).classes("text-sm text-amber-800 dark:text-amber-200")
+
         def render_result(result: BacktestPageRunResult) -> None:
             result_panel.clear()
             template_result = result.run_result.template_results[0]
             summary = template_result.summary_metrics
             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(
                     "w-full rounded-2xl border border-slate-200 bg-white shadow-sm dark:border-slate-800 dark:bg-slate-900"
                 ):
-                    ui.label("Scenario Summary").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
+                    ui.label("Scenario Results").classes("text-lg font-semibold text-slate-900 dark:text-slate-100")
                     ui.label(f"Template: {template_result.template_name}").classes(
                         "text-sm text-slate-500 dark:text-slate-400"
                     )
@@ -216,9 +272,11 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                     parse_iso_date(end_input.value, "End date"),
                 )
             except (ValueError, KeyError):
+                render_seeded_summary(entry_spot=None)
                 return
             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}")
+            render_seeded_summary(entry_spot=entry_spot)
 
         def run_backtest() -> None:
             validation_label.set_text("")
@@ -233,17 +291,25 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                     margin_call_ltv=float(ltv_input.value or 0.0),
                 )
             except (ValueError, KeyError) as exc:
-                result_panel.clear()
+                render_seeded_summary(entry_spot=None)
                 validation_label.set_text(str(exc))
+                render_result_validation(str(exc))
                 return
             except Exception:
-                result_panel.clear()
-                validation_label.set_text("Backtest failed. Please verify the scenario inputs and try again.")
+                render_seeded_summary(entry_spot=None)
+                message = "Backtest failed. Please verify the scenario inputs and try again."
+                validation_label.set_text(message)
+                render_result_validation(message)
                 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())
+        template_select.on_value_change(lambda _event: render_seeded_summary())
+        units_input.on_value_change(lambda _event: render_seeded_summary())
+        loan_input.on_value_change(lambda _event: render_seeded_summary())
+        ltv_input.on_value_change(lambda _event: render_seeded_summary())
         run_button.on_click(lambda: run_backtest())
+        render_seeded_summary(entry_spot=default_entry_spot)
         run_backtest()