012 dashboard stats (#32)

* plan

* dashboard stats

* show gallons and goal, cents per mile for mileage

---------

Co-authored-by: aligneddev <aligneddev@github.com>

Author: aligneddev

specs/012-dashboard-stats/checklists/requirements.md

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+# Specification Quality Checklist: Rider Dashboard Statistics
+
+**Purpose**: Validate specification completeness and quality before proceeding to planning  
+**Created**: 2026-04-06  
+**Feature**: [spec.md](../spec.md)
+
+## Content Quality
+
+- [x] No implementation details (languages, frameworks, APIs)
+- [x] Focused on user value and business needs
+- [x] Written for non-technical stakeholders
+- [x] All mandatory sections completed
+
+## Requirement Completeness
+
+- [x] No [NEEDS CLARIFICATION] markers remain
+- [x] Requirements are testable and unambiguous
+- [x] Success criteria are measurable
+- [x] Success criteria are technology-agnostic (no implementation details)
+- [x] All acceptance scenarios are defined
+- [x] Edge cases are identified
+- [x] Scope is clearly bounded
+- [x] Dependencies and assumptions identified
+
+## Feature Readiness
+
+- [x] All functional requirements have clear acceptance criteria
+- [x] User scenarios cover primary flows
+- [x] Feature meets measurable outcomes defined in Success Criteria
+- [x] No implementation details leak into specification
+
+## Notes
+
+- Clarifications resolved: baseline averages include average miles per ride and average ride duration.
+- Clarifications resolved: first optional suggestions are estimated gallons avoided and goal progress.
+- Specification is ready for `/speckit.plan`.

specs/012-dashboard-stats/contracts/api-contracts.md

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+# API Contracts: Rider Dashboard Statistics
+
+**Feature**: 012-dashboard-stats  
+**Date**: 2026-04-06  
+**Primary base paths**: `/api/dashboard`, `/api/users/me/settings`
+
+---
+
+## New Endpoint
+
+### `GET /api/dashboard`
+
+Authenticated rider-only endpoint returning the full dashboard view model.
+
+```csharp
+public sealed record DashboardResponse(
+    DashboardTotals Totals,
+    DashboardAverages Averages,
+    DashboardCharts Charts,
+    IReadOnlyList<DashboardMetricSuggestion> Suggestions,
+    DashboardMissingData MissingData,
+    DateTime GeneratedAtUtc
+);
+
+public sealed record DashboardTotals(
+    DashboardMileageMetric CurrentMonthMiles,
+    DashboardMileageMetric YearToDateMiles,
+    DashboardMileageMetric AllTimeMiles,
+    DashboardMoneySaved MoneySaved
+);
+
+public sealed record DashboardMileageMetric(
+    decimal Miles,
+    int RideCount,
+    string Period
+);
+
+public sealed record DashboardMoneySaved(
+    decimal? MileageRateSavings,
+    decimal? FuelCostAvoided,
+    decimal? CombinedSavings,
+    int QualifiedRideCount
+);
+
+public sealed record DashboardAverages(
+    decimal? AverageTemperature,
+    decimal? AverageMilesPerRide,
+    decimal? AverageRideMinutes
+);
+
+public sealed record DashboardCharts(
+    IReadOnlyList<DashboardMileagePoint> MileageByMonth,
+    IReadOnlyList<DashboardSavingsPoint> SavingsByMonth
+);
+
+public sealed record DashboardMileagePoint(
+    string MonthKey,
+    string Label,
+    decimal Miles
+);
+
+public sealed record DashboardSavingsPoint(
+    string MonthKey,
+    string Label,
+    decimal? MileageRateSavings,
+    decimal? FuelCostAvoided,
+    decimal? CombinedSavings
+);
+
+public sealed record DashboardMetricSuggestion(
+    string MetricKey,
+    string Title,
+    string Description,
+    bool IsEnabled
+);
+
+public sealed record DashboardMissingData(
+    int RidesMissingSavingsSnapshot,
+    int RidesMissingGasPrice,
+    int RidesMissingTemperature,
+    int RidesMissingDuration
+);
+```
+
+**Behavior**:
+- `200 OK` for authenticated riders, even when no rides exist.
+- `401 Unauthorized` when the caller is unauthenticated.
+- Empty-state responses still contain empty chart arrays or zeroed mileage cards instead of errors.
+
+---
+
+## Modified Existing Contract: `UserSettingsUpsertRequest`
+
+File: `src/BikeTracking.Api/Contracts/UsersContracts.cs`
+
+```csharp
+public sealed record UserSettingsUpsertRequest(
+    decimal? AverageCarMpg,
+    decimal? YearlyGoalMiles,
+    decimal? OilChangePrice,
+    decimal? MileageRateCents,
+    string? LocationLabel,
+    decimal? Latitude,
+    decimal? Longitude,
+    bool? DashboardGallonsAvoidedEnabled,
+    bool? DashboardGoalProgressEnabled
+);
+```
+
+**Semantics**:
+- Both new fields participate in the existing partial-update semantics.
+- Omitting a field leaves the prior persisted value unchanged.
+
+---
+
+## Modified Existing Contract: `UserSettingsView`
+
+```csharp
+public sealed record UserSettingsView(
+    decimal? AverageCarMpg,
+    decimal? YearlyGoalMiles,
+    decimal? OilChangePrice,
+    decimal? MileageRateCents,
+    string? LocationLabel,
+    decimal? Latitude,
+    decimal? Longitude,
+    bool DashboardGallonsAvoidedEnabled,
+    bool DashboardGoalProgressEnabled,
+    DateTime? UpdatedAtUtc
+);
+```
+
+These fields allow the frontend to render suggestion state and settings defaults consistently.
+
+---
+
+## Modified Existing Event Payload Factories
+
+Files:
+- `RideRecordedEventPayload.cs`
+- `RideEditedEventPayload.cs`
+
+New additive optional fields:
+
+```csharp
+decimal? SnapshotAverageCarMpg = null,
+decimal? SnapshotMileageRateCents = null,
+decimal? SnapshotYearlyGoalMiles = null,
+decimal? SnapshotOilChangePrice = null
+```
+
+These are additive and backwards-compatible for existing call sites.
+
+---
+
+## Frontend TypeScript Contracts
+
+### `dashboard-api.ts`
+
+```typescript
+export interface DashboardResponse {
+  totals: DashboardTotals;
+  averages: DashboardAverages;
+  charts: DashboardCharts;
+  suggestions: DashboardMetricSuggestion[];
+  missingData: DashboardMissingData;
+  generatedAtUtc: string;
+}
+
+export interface DashboardTotals {
+  currentMonthMiles: DashboardMileageMetric;
+  yearToDateMiles: DashboardMileageMetric;
+  allTimeMiles: DashboardMileageMetric;
+  moneySaved: DashboardMoneySaved;
+}
+
+export interface DashboardMileageMetric {
+  miles: number;
+  rideCount: number;
+  period: string;
+}
+
+export interface DashboardMoneySaved {
+  mileageRateSavings: number | null;
+  fuelCostAvoided: number | null;
+  combinedSavings: number | null;
+  qualifiedRideCount: number;
+}
+
+export interface DashboardAverages {
+  averageTemperature: number | null;
+  averageMilesPerRide: number | null;
+  averageRideMinutes: number | null;
+}
+
+export interface DashboardCharts {
+  mileageByMonth: DashboardMileagePoint[];
+  savingsByMonth: DashboardSavingsPoint[];
+}
+
+export interface DashboardMileagePoint {
+  monthKey: string;
+  label: string;
+  miles: number;
+}
+
+export interface DashboardSavingsPoint {
+  monthKey: string;
+  label: string;
+  mileageRateSavings: number | null;
+  fuelCostAvoided: number | null;
+  combinedSavings: number | null;
+}
+
+export interface DashboardMetricSuggestion {
+  metricKey: "gallonsAvoided" | "goalProgress";
+  title: string;
+  description: string;
+  isEnabled: boolean;
+}
+
+export interface DashboardMissingData {
+  ridesMissingSavingsSnapshot: number;
+  ridesMissingGasPrice: number;
+  ridesMissingTemperature: number;
+  ridesMissingDuration: number;
+}
+```
+
+### `users-api.ts`
+
+Add to both request and response interfaces:
+
+```typescript
+dashboardGallonsAvoidedEnabled?: boolean | null;
+dashboardGoalProgressEnabled?: boolean | null;
+```
+
+For the view shape:
+
+```typescript
+dashboardGallonsAvoidedEnabled: boolean;
+dashboardGoalProgressEnabled: boolean;
+```
+
+---
+
+## Compatibility Notes
+
+- Existing user settings callers remain compatible because the new fields are additive.
+- Existing ride-history API consumers remain unchanged.
+- The dashboard no longer depends on ride-history pagination hacks, but `/miles` can be preserved as
+  a client-side redirect to the new dashboard route for continuity.