Initial project setup for PhaseFlow

Set up Next.js 16 project with TypeScript for a training decision app
that integrates menstrual cycle phases with Garmin biometrics for
Hashimoto's thyroiditis management.

Stack: Next.js 16, React 19, Tailwind/shadcn, PocketBase, Drizzle,
Zod, Resend, Vitest, Biome, Lefthook, Nix dev environment.

Includes:
- 7 page routes (dashboard, login, settings, calendar, history, plan)
- 12 API endpoints (garmin, user, cycle, calendar, overrides, cron)
- Core lib utilities (decision engine, cycle phases, nutrition, ICS)
- Type definitions and component scaffolding
- Python script for Garmin token bootstrapping
- Initial unit tests for cycle utilities

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/api/calendar/[userId]/[token].ics/route.ts

@@ -0,0 +1,23 @@
+// ABOUTME: API route for ICS calendar feed generation.
+// ABOUTME: Returns subscribable iCal feed with cycle phases and warnings.
+import { type NextRequest, NextResponse } from "next/server";
+
+interface RouteParams {
+  params: Promise<{
+    userId: string;
+    token: string;
+  }>;
+}
+
+export async function GET(_request: NextRequest, { params }: RouteParams) {
+  const { userId, token } = await params;
+  void token; // Token will be used for validation
+  // TODO: Implement ICS feed generation
+  // Validate token, generate ICS content, return with correct headers
+  return new NextResponse(`ICS feed for user ${userId} not implemented`, {
+    status: 501,
+    headers: {
+      "Content-Type": "text/calendar; charset=utf-8",
+    },
+  });
+}

src/app/api/calendar/regenerate-token/route.ts

@@ -0,0 +1,8 @@
+// ABOUTME: API route for regenerating calendar subscription token.
+// ABOUTME: Creates new random token, invalidating old calendar URLs.
+import { NextResponse } from "next/server";
+
+export async function POST() {
+  // TODO: Implement token regeneration
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/cron/garmin-sync/route.ts

@@ -0,0 +1,16 @@
+// ABOUTME: Cron endpoint for syncing Garmin data.
+// ABOUTME: Fetches body battery, HRV, and intensity minutes for all users.
+import { NextResponse } from "next/server";
+
+export async function POST(request: Request) {
+  // Verify cron secret
+  const authHeader = request.headers.get("authorization");
+  const expectedSecret = process.env.CRON_SECRET;
+
+  if (!expectedSecret || authHeader !== `Bearer ${expectedSecret}`) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  // TODO: Implement Garmin data sync
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/cron/notifications/route.ts

@@ -0,0 +1,16 @@
+// ABOUTME: Cron endpoint for sending daily email notifications.
+// ABOUTME: Sends morning training decision emails to all users.
+import { NextResponse } from "next/server";
+
+export async function POST(request: Request) {
+  // Verify cron secret
+  const authHeader = request.headers.get("authorization");
+  const expectedSecret = process.env.CRON_SECRET;
+
+  if (!expectedSecret || authHeader !== `Bearer ${expectedSecret}`) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  // TODO: Implement notification sending
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/cycle/current/route.ts

@@ -0,0 +1,8 @@
+// ABOUTME: API route for current cycle phase information.
+// ABOUTME: Returns current cycle day, phase, and phase limits.
+import { NextResponse } from "next/server";
+
+export async function GET() {
+  // TODO: Implement current cycle info
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/cycle/period/route.ts

@@ -0,0 +1,8 @@
+// ABOUTME: API route for logging period start dates.
+// ABOUTME: Recalculates all phase dates when period is logged.
+import { NextResponse } from "next/server";
+
+export async function POST() {
+  // TODO: Implement period logging
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/garmin/status/route.ts

@@ -0,0 +1,8 @@
+// ABOUTME: API route for checking Garmin connection status.
+// ABOUTME: Returns connection state and token expiry information.
+import { NextResponse } from "next/server";
+
+export async function GET() {
+  // TODO: Implement status check
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/garmin/tokens/route.ts

@@ -0,0 +1,13 @@
+// ABOUTME: API route for storing Garmin OAuth tokens.
+// ABOUTME: Accepts tokens from the bootstrap script and encrypts them for storage.
+import { NextResponse } from "next/server";
+
+export async function POST() {
+  // TODO: Implement token storage
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}
+
+export async function DELETE() {
+  // TODO: Implement token deletion
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/history/route.ts

@@ -0,0 +1,8 @@
+// ABOUTME: API route for historical daily logs.
+// ABOUTME: Returns paginated list of past training decisions and data.
+import { NextResponse } from "next/server";
+
+export async function GET() {
+  // TODO: Implement history retrieval
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/overrides/route.ts

@@ -0,0 +1,13 @@
+// ABOUTME: API route for managing training overrides.
+// ABOUTME: Handles flare, stress, sleep, and PMS override toggles.
+import { NextResponse } from "next/server";
+
+export async function POST() {
+  // TODO: Implement override setting
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}
+
+export async function DELETE() {
+  // TODO: Implement override removal
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/today/route.ts

@@ -0,0 +1,8 @@
+// ABOUTME: API route for today's training decision and data.
+// ABOUTME: Returns complete daily snapshot with decision, biometrics, and nutrition.
+import { NextResponse } from "next/server";
+
+export async function GET() {
+  // TODO: Implement today's data retrieval
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/api/user/route.ts

@@ -0,0 +1,13 @@
+// ABOUTME: API route for user profile management.
+// ABOUTME: Handles GET for profile retrieval and PATCH for updates.
+import { NextResponse } from "next/server";
+
+export async function GET() {
+  // TODO: Implement user profile retrieval
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}
+
+export async function PATCH() {
+  // TODO: Implement user profile update
+  return NextResponse.json({ message: "Not implemented" }, { status: 501 });
+}

src/app/calendar/page.tsx

@@ -0,0 +1,11 @@
+// ABOUTME: In-app calendar view showing cycle phases.
+// ABOUTME: Displays monthly calendar with color-coded phases and ICS subscription info.
+export default function CalendarPage() {
+  return (
+    <div className="container mx-auto p-8">
+      <h1 className="text-2xl font-bold mb-8">Calendar</h1>
+      {/* Calendar view will be implemented here */}
+      <p className="text-gray-500">Calendar view placeholder</p>
+    </div>
+  );
+}

src/app/globals.css

@@ -0,0 +1,125 @@
+@import "tailwindcss";
+@import "tw-animate-css";
+
+@custom-variant dark (&:is(.dark *));
+
+@theme inline {
+  --color-background: var(--background);
+  --color-foreground: var(--foreground);
+  --font-sans: var(--font-geist-sans);
+  --font-mono: var(--font-geist-mono);
+  --color-sidebar-ring: var(--sidebar-ring);
+  --color-sidebar-border: var(--sidebar-border);
+  --color-sidebar-accent-foreground: var(--sidebar-accent-foreground);
+  --color-sidebar-accent: var(--sidebar-accent);
+  --color-sidebar-primary-foreground: var(--sidebar-primary-foreground);
+  --color-sidebar-primary: var(--sidebar-primary);
+  --color-sidebar-foreground: var(--sidebar-foreground);
+  --color-sidebar: var(--sidebar);
+  --color-chart-5: var(--chart-5);
+  --color-chart-4: var(--chart-4);
+  --color-chart-3: var(--chart-3);
+  --color-chart-2: var(--chart-2);
+  --color-chart-1: var(--chart-1);
+  --color-ring: var(--ring);
+  --color-input: var(--input);
+  --color-border: var(--border);
+  --color-destructive: var(--destructive);
+  --color-accent-foreground: var(--accent-foreground);
+  --color-accent: var(--accent);
+  --color-muted-foreground: var(--muted-foreground);
+  --color-muted: var(--muted);
+  --color-secondary-foreground: var(--secondary-foreground);
+  --color-secondary: var(--secondary);
+  --color-primary-foreground: var(--primary-foreground);
+  --color-primary: var(--primary);
+  --color-popover-foreground: var(--popover-foreground);
+  --color-popover: var(--popover);
+  --color-card-foreground: var(--card-foreground);
+  --color-card: var(--card);
+  --radius-sm: calc(var(--radius) - 4px);
+  --radius-md: calc(var(--radius) - 2px);
+  --radius-lg: var(--radius);
+  --radius-xl: calc(var(--radius) + 4px);
+  --radius-2xl: calc(var(--radius) + 8px);
+  --radius-3xl: calc(var(--radius) + 12px);
+  --radius-4xl: calc(var(--radius) + 16px);
+}
+
+:root {
+  --radius: 0.625rem;
+  --background: oklch(1 0 0);
+  --foreground: oklch(0.145 0 0);
+  --card: oklch(1 0 0);
+  --card-foreground: oklch(0.145 0 0);
+  --popover: oklch(1 0 0);
+  --popover-foreground: oklch(0.145 0 0);
+  --primary: oklch(0.205 0 0);
+  --primary-foreground: oklch(0.985 0 0);
+  --secondary: oklch(0.97 0 0);
+  --secondary-foreground: oklch(0.205 0 0);
+  --muted: oklch(0.97 0 0);
+  --muted-foreground: oklch(0.556 0 0);
+  --accent: oklch(0.97 0 0);
+  --accent-foreground: oklch(0.205 0 0);
+  --destructive: oklch(0.577 0.245 27.325);
+  --border: oklch(0.922 0 0);
+  --input: oklch(0.922 0 0);
+  --ring: oklch(0.708 0 0);
+  --chart-1: oklch(0.646 0.222 41.116);
+  --chart-2: oklch(0.6 0.118 184.704);
+  --chart-3: oklch(0.398 0.07 227.392);
+  --chart-4: oklch(0.828 0.189 84.429);
+  --chart-5: oklch(0.769 0.188 70.08);
+  --sidebar: oklch(0.985 0 0);
+  --sidebar-foreground: oklch(0.145 0 0);
+  --sidebar-primary: oklch(0.205 0 0);
+  --sidebar-primary-foreground: oklch(0.985 0 0);
+  --sidebar-accent: oklch(0.97 0 0);
+  --sidebar-accent-foreground: oklch(0.205 0 0);
+  --sidebar-border: oklch(0.922 0 0);
+  --sidebar-ring: oklch(0.708 0 0);
+}
+
+.dark {
+  --background: oklch(0.145 0 0);
+  --foreground: oklch(0.985 0 0);
+  --card: oklch(0.205 0 0);
+  --card-foreground: oklch(0.985 0 0);
+  --popover: oklch(0.205 0 0);
+  --popover-foreground: oklch(0.985 0 0);
+  --primary: oklch(0.922 0 0);
+  --primary-foreground: oklch(0.205 0 0);
+  --secondary: oklch(0.269 0 0);
+  --secondary-foreground: oklch(0.985 0 0);
+  --muted: oklch(0.269 0 0);
+  --muted-foreground: oklch(0.708 0 0);
+  --accent: oklch(0.269 0 0);
+  --accent-foreground: oklch(0.985 0 0);
+  --destructive: oklch(0.704 0.191 22.216);
+  --border: oklch(1 0 0 / 10%);
+  --input: oklch(1 0 0 / 15%);
+  --ring: oklch(0.556 0 0);
+  --chart-1: oklch(0.488 0.243 264.376);
+  --chart-2: oklch(0.696 0.17 162.48);
+  --chart-3: oklch(0.769 0.188 70.08);
+  --chart-4: oklch(0.627 0.265 303.9);
+  --chart-5: oklch(0.645 0.246 16.439);
+  --sidebar: oklch(0.205 0 0);
+  --sidebar-foreground: oklch(0.985 0 0);
+  --sidebar-primary: oklch(0.488 0.243 264.376);
+  --sidebar-primary-foreground: oklch(0.985 0 0);
+  --sidebar-accent: oklch(0.269 0 0);
+  --sidebar-accent-foreground: oklch(0.985 0 0);
+  --sidebar-border: oklch(1 0 0 / 10%);
+  --sidebar-ring: oklch(0.556 0 0);
+}
+
+@layer base {
+  * {
+    @apply border-border outline-ring/50;
+  }
+  body {
+    @apply bg-background text-foreground;
+  }
+}

src/app/history/page.tsx

@@ -0,0 +1,11 @@
+// ABOUTME: Historical data view for past training decisions.
+// ABOUTME: Shows table of daily logs with biometrics and decisions.
+export default function HistoryPage() {
+  return (
+    <div className="container mx-auto p-8">
+      <h1 className="text-2xl font-bold mb-8">History</h1>
+      {/* History table will be implemented here */}
+      <p className="text-gray-500">History table placeholder</p>
+    </div>
+  );
+}

src/app/layout.tsx

@@ -0,0 +1,37 @@
+// ABOUTME: Root layout for PhaseFlow application.
+// ABOUTME: Configures fonts, metadata, and global styles.
+import type { Metadata } from "next";
+import { Geist, Geist_Mono } from "next/font/google";
+import "./globals.css";
+
+const geistSans = Geist({
+  variable: "--font-geist-sans",
+  subsets: ["latin"],
+});
+
+const geistMono = Geist_Mono({
+  variable: "--font-geist-mono",
+  subsets: ["latin"],
+});
+
+export const metadata: Metadata = {
+  title: "PhaseFlow",
+  description:
+    "Automated training decisions for Hashimoto's thyroiditis based on menstrual cycle phases and Garmin biometrics",
+};
+
+export default function RootLayout({
+  children,
+}: Readonly<{
+  children: React.ReactNode;
+}>) {
+  return (
+    <html lang="en">
+      <body
+        className={`${geistSans.variable} ${geistMono.variable} antialiased`}
+      >
+        {children}
+      </body>
+    </html>
+  );
+}

src/app/login/page.tsx

@@ -0,0 +1,13 @@
+// ABOUTME: Login page for user authentication.
+// ABOUTME: Provides email/password login form using PocketBase auth.
+export default function LoginPage() {
+  return (
+    <div className="flex min-h-screen items-center justify-center">
+      <div className="w-full max-w-md space-y-8 p-8">
+        <h1 className="text-2xl font-bold text-center">PhaseFlow Login</h1>
+        {/* Login form will be implemented here */}
+        <p className="text-center text-gray-500">Login form placeholder</p>
+      </div>
+    </div>
+  );
+}

src/app/page.tsx

@@ -0,0 +1,28 @@
+// ABOUTME: Main dashboard page for PhaseFlow.
+// ABOUTME: Displays today's training decision, biometrics, and quick actions.
+export default function Dashboard() {
+  return (
+    <div className="min-h-screen bg-zinc-50 dark:bg-black">
+      <header className="border-b bg-white dark:bg-zinc-900 px-6 py-4">
+        <div className="container mx-auto flex justify-between items-center">
+          <h1 className="text-xl font-bold">PhaseFlow</h1>
+          <a
+            href="/settings"
+            className="text-sm text-zinc-600 hover:text-zinc-900"
+          >
+            Settings
+          </a>
+        </div>
+      </header>
+
+      <main className="container mx-auto p-6">
+        <div className="text-center py-12">
+          <p className="text-zinc-500">Dashboard placeholder</p>
+          <p className="text-sm text-zinc-400 mt-2">
+            Connect your Garmin and set your period date to get started.
+          </p>
+        </div>
+      </main>
+    </div>
+  );
+}

src/app/plan/page.tsx

@@ -0,0 +1,11 @@
+// ABOUTME: Exercise plan reference page.
+// ABOUTME: Displays the full monthly exercise plan by phase.
+export default function PlanPage() {
+  return (
+    <div className="container mx-auto p-8">
+      <h1 className="text-2xl font-bold mb-8">Exercise Plan</h1>
+      {/* Exercise plan content will be implemented here */}
+      <p className="text-gray-500">Exercise plan placeholder</p>
+    </div>
+  );
+}

src/app/settings/garmin/page.tsx

@@ -0,0 +1,13 @@
+// ABOUTME: Garmin connection settings page.
+// ABOUTME: Allows users to paste OAuth tokens from the bootstrap script.
+export default function GarminSettingsPage() {
+  return (
+    <div className="container mx-auto p-8">
+      <h1 className="text-2xl font-bold mb-8">
+        Settings &gt; Garmin Connection
+      </h1>
+      {/* Garmin token input will be implemented here */}
+      <p className="text-gray-500">Garmin settings placeholder</p>
+    </div>
+  );
+}

src/app/settings/page.tsx

@@ -0,0 +1,11 @@
+// ABOUTME: User settings page for profile and preferences.
+// ABOUTME: Allows configuration of notification time, timezone, and cycle length.
+export default function SettingsPage() {
+  return (
+    <div className="container mx-auto p-8">
+      <h1 className="text-2xl font-bold mb-8">Settings</h1>
+      {/* Settings form will be implemented here */}
+      <p className="text-gray-500">Settings form placeholder</p>
+    </div>
+  );
+}

src/components/calendar/day-cell.tsx

@@ -0,0 +1,38 @@
+// ABOUTME: Individual day cell for calendar views.
+// ABOUTME: Shows day number with phase-appropriate background color.
+import type { CyclePhase } from "@/types";
+
+interface DayCellProps {
+  date: Date;
+  cycleDay: number;
+  phase: CyclePhase;
+  isToday: boolean;
+  onClick?: () => void;
+}
+
+const PHASE_COLORS: Record<CyclePhase, string> = {
+  MENSTRUAL: "bg-blue-100",
+  FOLLICULAR: "bg-green-100",
+  OVULATION: "bg-purple-100",
+  EARLY_LUTEAL: "bg-yellow-100",
+  LATE_LUTEAL: "bg-red-100",
+};
+
+export function DayCell({
+  date,
+  cycleDay,
+  phase,
+  isToday,
+  onClick,
+}: DayCellProps) {
+  return (
+    <button
+      type="button"
+      onClick={onClick}
+      className={`p-2 rounded ${PHASE_COLORS[phase]} ${isToday ? "ring-2 ring-black" : ""}`}
+    >
+      <span className="text-sm font-medium">{date.getDate()}</span>
+      <span className="text-xs text-gray-500 block">Day {cycleDay}</span>
+    </button>
+  );
+}

src/components/calendar/month-view.tsx

@@ -0,0 +1,32 @@
+// ABOUTME: Full month calendar view component.
+// ABOUTME: Displays calendar grid with phase colors and day details.
+interface MonthViewProps {
+  year: number;
+  month: number;
+  lastPeriodDate: Date;
+  cycleLength: number;
+}
+
+export function MonthView({
+  year,
+  month,
+  lastPeriodDate,
+  cycleLength,
+}: MonthViewProps) {
+  return (
+    <div className="rounded-lg border p-4">
+      <h2 className="text-xl font-bold mb-4">
+        {new Date(year, month).toLocaleDateString("en-US", {
+          month: "long",
+          year: "numeric",
+        })}
+      </h2>
+      {/* Calendar grid will be implemented here */}
+      <p className="text-gray-500">Month view placeholder</p>
+      <p className="text-xs text-gray-400">
+        Cycle length: {cycleLength} days, Last period:{" "}
+        {lastPeriodDate.toLocaleDateString()}
+      </p>
+    </div>
+  );
+}

src/components/dashboard/data-panel.tsx

@@ -0,0 +1,34 @@
+// ABOUTME: Dashboard panel showing biometric data.
+// ABOUTME: Displays body battery, HRV, and intensity minutes.
+interface DataPanelProps {
+  bodyBatteryCurrent: number | null;
+  bodyBatteryYesterdayLow: number | null;
+  hrvStatus: string;
+  weekIntensity: number;
+  phaseLimit: number;
+  remainingMinutes: number;
+}
+
+export function DataPanel({
+  bodyBatteryCurrent,
+  bodyBatteryYesterdayLow,
+  hrvStatus,
+  weekIntensity,
+  phaseLimit,
+  remainingMinutes,
+}: DataPanelProps) {
+  return (
+    <div className="rounded-lg border p-4">
+      <h3 className="font-semibold mb-4">YOUR DATA</h3>
+      <ul className="space-y-2 text-sm">
+        <li>Body Battery: {bodyBatteryCurrent ?? "N/A"}</li>
+        <li>Yesterday Low: {bodyBatteryYesterdayLow ?? "N/A"}</li>
+        <li>HRV: {hrvStatus}</li>
+        <li>
+          Week: {weekIntensity}/{phaseLimit} min
+        </li>
+        <li>Remaining: {remainingMinutes} min</li>
+      </ul>
+    </div>
+  );
+}

src/components/dashboard/decision-card.tsx

@@ -0,0 +1,17 @@
+// ABOUTME: Dashboard card displaying today's training decision.
+// ABOUTME: Shows decision status, icon, and reason prominently.
+import type { Decision } from "@/types";
+
+interface DecisionCardProps {
+  decision: Decision;
+}
+
+export function DecisionCard({ decision }: DecisionCardProps) {
+  return (
+    <div className="rounded-lg border p-6">
+      <div className="text-4xl mb-2">{decision.icon}</div>
+      <h2 className="text-2xl font-bold">{decision.status}</h2>
+      <p className="text-gray-600">{decision.reason}</p>
+    </div>
+  );
+}

src/components/dashboard/mini-calendar.tsx

@@ -0,0 +1,29 @@
+// ABOUTME: Compact calendar widget for the dashboard.
+// ABOUTME: Shows current month with color-coded cycle phases.
+interface MiniCalendarProps {
+  currentDate: Date;
+  cycleDay: number;
+  phase: string;
+}
+
+export function MiniCalendar({
+  currentDate,
+  cycleDay,
+  phase,
+}: MiniCalendarProps) {
+  return (
+    <div className="rounded-lg border p-4">
+      <h3 className="font-semibold mb-4">
+        Day {cycleDay} • {phase}
+      </h3>
+      <p className="text-sm text-gray-500">
+        {currentDate.toLocaleDateString("en-US", {
+          month: "long",
+          year: "numeric",
+        })}
+      </p>
+      {/* Full calendar grid will be implemented here */}
+      <p className="text-gray-400 text-xs mt-4">Calendar grid placeholder</p>
+    </div>
+  );
+}

src/components/dashboard/nutrition-panel.tsx

@@ -0,0 +1,20 @@
+// ABOUTME: Dashboard panel showing nutrition guidance.
+// ABOUTME: Displays seed cycling and macro recommendations.
+import type { NutritionGuidance } from "@/types";
+
+interface NutritionPanelProps {
+  nutrition: NutritionGuidance;
+}
+
+export function NutritionPanel({ nutrition }: NutritionPanelProps) {
+  return (
+    <div className="rounded-lg border p-4">
+      <h3 className="font-semibold mb-4">NUTRITION TODAY</h3>
+      <ul className="space-y-2 text-sm">
+        <li>🌱 {nutrition.seeds}</li>
+        <li>🍽️ Carbs: {nutrition.carbRange}</li>
+        <li>🥑 Keto: {nutrition.ketoGuidance}</li>
+      </ul>
+    </div>
+  );
+}

src/components/dashboard/override-toggles.tsx

@@ -0,0 +1,41 @@
+// ABOUTME: Dashboard component for emergency training overrides.
+// ABOUTME: Provides toggles for flare, stress, sleep, and PMS modes.
+import type { OverrideType } from "@/types";
+
+interface OverrideTogglesProps {
+  activeOverrides: OverrideType[];
+  onToggle: (override: OverrideType) => void;
+}
+
+const OVERRIDE_OPTIONS: { type: OverrideType; label: string }[] = [
+  { type: "flare", label: "Flare Mode" },
+  { type: "stress", label: "High Stress" },
+  { type: "sleep", label: "Poor Sleep" },
+  { type: "pms", label: "PMS Symptoms" },
+];
+
+export function OverrideToggles({
+  activeOverrides,
+  onToggle,
+}: OverrideTogglesProps) {
+  return (
+    <div className="rounded-lg border p-4">
+      <h3 className="font-semibold mb-4">OVERRIDES</h3>
+      <ul className="space-y-2">
+        {OVERRIDE_OPTIONS.map(({ type, label }) => (
+          <li key={type}>
+            <label className="flex items-center gap-2 cursor-pointer">
+              <input
+                type="checkbox"
+                checked={activeOverrides.includes(type)}
+                onChange={() => onToggle(type)}
+                className="rounded"
+              />
+              {label}
+            </label>
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}

src/lib/cycle.test.ts

@@ -0,0 +1,62 @@
+// ABOUTME: Unit tests for cycle phase calculation utilities.
+// ABOUTME: Tests getCycleDay, getPhase, and phase limit functions.
+import { describe, expect, it } from "vitest";
+
+import { getCycleDay, getPhase, getPhaseLimit } from "./cycle";
+
+describe("getCycleDay", () => {
+  it("returns 1 on the first day of the cycle", () => {
+    const lastPeriod = new Date("2025-01-01");
+    const currentDate = new Date("2025-01-01");
+    expect(getCycleDay(lastPeriod, 31, currentDate)).toBe(1);
+  });
+
+  it("returns correct day within cycle", () => {
+    const lastPeriod = new Date("2025-01-01");
+    const currentDate = new Date("2025-01-15");
+    expect(getCycleDay(lastPeriod, 31, currentDate)).toBe(15);
+  });
+
+  it("wraps around after cycle length", () => {
+    const lastPeriod = new Date("2025-01-01");
+    const currentDate = new Date("2025-02-01"); // 31 days later
+    expect(getCycleDay(lastPeriod, 31, currentDate)).toBe(1);
+  });
+});
+
+describe("getPhase", () => {
+  it("returns MENSTRUAL for days 1-3", () => {
+    expect(getPhase(1)).toBe("MENSTRUAL");
+    expect(getPhase(3)).toBe("MENSTRUAL");
+  });
+
+  it("returns FOLLICULAR for days 4-14", () => {
+    expect(getPhase(4)).toBe("FOLLICULAR");
+    expect(getPhase(14)).toBe("FOLLICULAR");
+  });
+
+  it("returns OVULATION for days 15-16", () => {
+    expect(getPhase(15)).toBe("OVULATION");
+    expect(getPhase(16)).toBe("OVULATION");
+  });
+
+  it("returns EARLY_LUTEAL for days 17-24", () => {
+    expect(getPhase(17)).toBe("EARLY_LUTEAL");
+    expect(getPhase(24)).toBe("EARLY_LUTEAL");
+  });
+
+  it("returns LATE_LUTEAL for days 25-31", () => {
+    expect(getPhase(25)).toBe("LATE_LUTEAL");
+    expect(getPhase(31)).toBe("LATE_LUTEAL");
+  });
+});
+
+describe("getPhaseLimit", () => {
+  it("returns correct weekly limits for each phase", () => {
+    expect(getPhaseLimit("MENSTRUAL")).toBe(30);
+    expect(getPhaseLimit("FOLLICULAR")).toBe(120);
+    expect(getPhaseLimit("OVULATION")).toBe(80);
+    expect(getPhaseLimit("EARLY_LUTEAL")).toBe(100);
+    expect(getPhaseLimit("LATE_LUTEAL")).toBe(50);
+  });
+});

src/lib/cycle.ts

@@ -0,0 +1,73 @@
+// ABOUTME: Cycle phase calculation utilities.
+// ABOUTME: Determines current cycle day and phase from last period date.
+import type { CyclePhase, PhaseConfig } from "@/types";
+
+export const PHASE_CONFIGS: PhaseConfig[] = [
+  {
+    name: "MENSTRUAL",
+    days: [1, 3],
+    weeklyLimit: 30,
+    dailyAvg: 10,
+    trainingType: "Gentle rebounding only",
+  },
+  {
+    name: "FOLLICULAR",
+    days: [4, 14],
+    weeklyLimit: 120,
+    dailyAvg: 17,
+    trainingType: "Strength + rebounding",
+  },
+  {
+    name: "OVULATION",
+    days: [15, 16],
+    weeklyLimit: 80,
+    dailyAvg: 40,
+    trainingType: "Peak performance",
+  },
+  {
+    name: "EARLY_LUTEAL",
+    days: [17, 24],
+    weeklyLimit: 100,
+    dailyAvg: 14,
+    trainingType: "Moderate training",
+  },
+  {
+    name: "LATE_LUTEAL",
+    days: [25, 31],
+    weeklyLimit: 50,
+    dailyAvg: 8,
+    trainingType: "Gentle rebounding ONLY",
+  },
+];
+
+export function getCycleDay(
+  lastPeriodDate: Date,
+  cycleLength: number,
+  currentDate: Date = new Date(),
+): number {
+  const diffMs = currentDate.getTime() - lastPeriodDate.getTime();
+  const diffDays = Math.floor(diffMs / (1000 * 60 * 60 * 24));
+  return (diffDays % cycleLength) + 1;
+}
+
+export function getPhase(cycleDay: number): CyclePhase {
+  for (const config of PHASE_CONFIGS) {
+    if (cycleDay >= config.days[0] && cycleDay <= config.days[1]) {
+      return config.name;
+    }
+  }
+  // Default to late luteal for any days beyond 31
+  return "LATE_LUTEAL";
+}
+
+export function getPhaseConfig(phase: CyclePhase): PhaseConfig {
+  const config = PHASE_CONFIGS.find((c) => c.name === phase);
+  if (!config) {
+    throw new Error(`Unknown phase: ${phase}`);
+  }
+  return config;
+}
+
+export function getPhaseLimit(phase: CyclePhase): number {
+  return getPhaseConfig(phase).weeklyLimit;
+}

src/lib/decision-engine.ts

@@ -0,0 +1,64 @@
+// ABOUTME: Training decision engine based on biometric and cycle data.
+// ABOUTME: Implements priority-based rules for daily training recommendations.
+import type { DailyData, Decision } from "@/types";
+
+export function getTrainingDecision(data: DailyData): Decision {
+  const {
+    hrvStatus,
+    bbYesterdayLow,
+    phase,
+    weekIntensity,
+    phaseLimit,
+    bbCurrent,
+  } = data;
+
+  if (hrvStatus === "Unbalanced") {
+    return { status: "REST", reason: "HRV Unbalanced", icon: "🛑" };
+  }
+
+  if (bbYesterdayLow < 30) {
+    return { status: "REST", reason: "BB too depleted", icon: "🛑" };
+  }
+
+  if (phase === "LATE_LUTEAL") {
+    return {
+      status: "GENTLE",
+      reason: "Gentle rebounding only (10-15min)",
+      icon: "🟡",
+    };
+  }
+
+  if (phase === "MENSTRUAL") {
+    return {
+      status: "GENTLE",
+      reason: "Gentle rebounding only (10min)",
+      icon: "🟡",
+    };
+  }
+
+  if (weekIntensity >= phaseLimit) {
+    return {
+      status: "REST",
+      reason: "WEEKLY LIMIT REACHED - Rest",
+      icon: "🛑",
+    };
+  }
+
+  if (bbCurrent < 75) {
+    return {
+      status: "LIGHT",
+      reason: "Light activity only - BB not recovered",
+      icon: "🟡",
+    };
+  }
+
+  if (bbCurrent < 85) {
+    return { status: "REDUCED", reason: "Reduce intensity 25%", icon: "🟡" };
+  }
+
+  return {
+    status: "TRAIN",
+    reason: "OK to train - follow phase plan",
+    icon: "✅",
+  };
+}

src/lib/email.ts

@@ -0,0 +1,83 @@
+// ABOUTME: Email sending utilities using Resend.
+// ABOUTME: Sends daily training notifications and period confirmation emails.
+import { Resend } from "resend";
+
+const resend = new Resend(process.env.RESEND_API_KEY);
+
+const EMAIL_FROM = process.env.EMAIL_FROM || "phaseflow@example.com";
+
+export interface DailyEmailData {
+  to: string;
+  cycleDay: number;
+  phase: string;
+  decision: {
+    status: string;
+    reason: string;
+    icon: string;
+  };
+  bodyBatteryCurrent: number | null;
+  bodyBatteryYesterdayLow: number | null;
+  hrvStatus: string;
+  weekIntensity: number;
+  phaseLimit: number;
+  remainingMinutes: number;
+  seeds: string;
+  carbRange: string;
+  ketoGuidance: string;
+}
+
+export async function sendDailyEmail(data: DailyEmailData): Promise<void> {
+  const subject = `Today's Training: ${data.decision.icon} ${data.decision.status}`;
+
+  const body = `Good morning!
+
+📅 CYCLE DAY: ${data.cycleDay} (${data.phase})
+
+💪 TODAY'S PLAN:
+${data.decision.icon} ${data.decision.reason}
+
+📊 YOUR DATA:
+• Body Battery Now: ${data.bodyBatteryCurrent ?? "N/A"}
+• Yesterday's Low: ${data.bodyBatteryYesterdayLow ?? "N/A"}
+• HRV Status: ${data.hrvStatus}
+• Week Intensity: ${data.weekIntensity} / ${data.phaseLimit} minutes
+• Remaining: ${data.remainingMinutes} minutes
+
+🌱 SEEDS: ${data.seeds}
+
+🍽️ MACROS: ${data.carbRange}
+🥑 KETO: ${data.ketoGuidance}
+
+---
+Auto-generated by PhaseFlow`;
+
+  await resend.emails.send({
+    from: EMAIL_FROM,
+    to: data.to,
+    subject,
+    text: body,
+  });
+}
+
+export async function sendPeriodConfirmationEmail(
+  to: string,
+  lastPeriodDate: Date,
+  cycleLength: number,
+): Promise<void> {
+  const subject = "🔵 Period Tracking Updated";
+
+  const body = `Your cycle has been reset. Last period: ${lastPeriodDate.toLocaleDateString()}
+Phase calendar updated for next ${cycleLength} days.
+
+Your calendar will update automatically within 24 hours.
+
+---
+Auto-generated by PhaseFlow`;
+
+  await resend.emails.send({
+    from: EMAIL_FROM,
+    to,
+    subject,
+    text: body,
+  });
+}

src/lib/encryption.ts

@@ -0,0 +1,49 @@
+// ABOUTME: AES-256 encryption utilities for sensitive data like Garmin tokens.
+// ABOUTME: Provides encrypt/decrypt functions using environment-based keys.
+import { createCipheriv, createDecipheriv, randomBytes } from "node:crypto";
+
+const ALGORITHM = "aes-256-gcm";
+const IV_LENGTH = 16;
+
+function getEncryptionKey(): Buffer {
+  const key = process.env.ENCRYPTION_KEY;
+  if (!key) {
+    throw new Error("ENCRYPTION_KEY environment variable is required");
+  }
+  // Ensure key is exactly 32 bytes for AES-256
+  return Buffer.from(key.padEnd(32, "0").slice(0, 32));
+}
+
+export function encrypt(plaintext: string): string {
+  const key = getEncryptionKey();
+  const iv = randomBytes(IV_LENGTH);
+  const cipher = createCipheriv(ALGORITHM, key, iv);
+
+  let encrypted = cipher.update(plaintext, "utf8", "hex");
+  encrypted += cipher.final("hex");
+
+  const authTag = cipher.getAuthTag();
+
+  // Format: iv:authTag:encrypted
+  return `${iv.toString("hex")}:${authTag.toString("hex")}:${encrypted}`;
+}
+
+export function decrypt(ciphertext: string): string {
+  const key = getEncryptionKey();
+  const [ivHex, authTagHex, encrypted] = ciphertext.split(":");
+
+  if (!ivHex || !authTagHex || !encrypted) {
+    throw new Error("Invalid ciphertext format");
+  }
+
+  const iv = Buffer.from(ivHex, "hex");
+  const authTag = Buffer.from(authTagHex, "hex");
+
+  const decipher = createDecipheriv(ALGORITHM, key, iv);
+  decipher.setAuthTag(authTag);
+
+  let decrypted = decipher.update(encrypted, "hex", "utf8");
+  decrypted += decipher.final("utf8");
+
+  return decrypted;
+}

src/lib/garmin.ts

@@ -0,0 +1,39 @@
+// ABOUTME: Garmin Connect API client using stored OAuth tokens.
+// ABOUTME: Fetches body battery, HRV, and intensity minutes from Garmin.
+import type { GarminTokens } from "@/types";
+
+const GARMIN_BASE_URL = "https://connect.garmin.com/modern/proxy";
+
+interface GarminApiOptions {
+  oauth2Token: string;
+}
+
+export async function fetchGarminData(
+  endpoint: string,
+  options: GarminApiOptions,
+): Promise<unknown> {
+  const response = await fetch(`${GARMIN_BASE_URL}${endpoint}`, {
+    headers: {
+      Authorization: `Bearer ${options.oauth2Token}`,
+      NK: "NT",
+    },
+  });
+
+  if (!response.ok) {
+    throw new Error(`Garmin API error: ${response.status}`);
+  }
+
+  return response.json();
+}
+
+export function isTokenExpired(tokens: GarminTokens): boolean {
+  const expiresAt = new Date(tokens.expires_at);
+  return expiresAt <= new Date();
+}
+
+export function daysUntilExpiry(tokens: GarminTokens): number {
+  const expiresAt = new Date(tokens.expires_at);
+  const now = new Date();
+  const diffMs = expiresAt.getTime() - now.getTime();
+  return Math.floor(diffMs / (1000 * 60 * 60 * 24));
+}

src/lib/ics.ts

@@ -0,0 +1,97 @@
+// ABOUTME: ICS calendar feed generation for cycle phase events.
+// ABOUTME: Creates subscribable calendar with phase blocks and warnings.
+import { createEvents, type EventAttributes } from "ics";
+
+import { getCycleDay, getPhase, PHASE_CONFIGS } from "./cycle";
+
+const PHASE_EMOJIS: Record<string, string> = {
+  MENSTRUAL: "🔵",
+  FOLLICULAR: "🟢",
+  OVULATION: "🟣",
+  EARLY_LUTEAL: "🟡",
+  LATE_LUTEAL: "🔴",
+};
+
+interface IcsGeneratorOptions {
+  lastPeriodDate: Date;
+  cycleLength: number;
+  monthsAhead?: number;
+}
+
+export function generateIcsFeed(options: IcsGeneratorOptions): string {
+  const { lastPeriodDate, cycleLength, monthsAhead = 3 } = options;
+  const events: EventAttributes[] = [];
+
+  const endDate = new Date();
+  endDate.setMonth(endDate.getMonth() + monthsAhead);
+
+  const currentDate = new Date(lastPeriodDate);
+  let currentPhase = getPhase(
+    getCycleDay(lastPeriodDate, cycleLength, currentDate),
+  );
+  let phaseStartDate = new Date(currentDate);
+
+  while (currentDate <= endDate) {
+    const cycleDay = getCycleDay(lastPeriodDate, cycleLength, currentDate);
+    const phase = getPhase(cycleDay);
+
+    // Add warning events
+    if (cycleDay === 22) {
+      events.push({
+        start: dateToArray(currentDate),
+        end: dateToArray(currentDate),
+        title: "⚠️ Late Luteal Phase Starts in 3 Days",
+        description: "Begin reducing training intensity",
+      });
+    }
+
+    if (cycleDay === 25) {
+      events.push({
+        start: dateToArray(currentDate),
+        end: dateToArray(currentDate),
+        title: "🔴 CRITICAL PHASE - Gentle Rebounding Only!",
+        description: "Late luteal phase - protect your cycle",
+      });
+    }
+
+    // Track phase changes
+    if (phase !== currentPhase) {
+      // Close previous phase event
+      events.push(createPhaseEvent(currentPhase, phaseStartDate, currentDate));
+      currentPhase = phase;
+      phaseStartDate = new Date(currentDate);
+    }
+
+    currentDate.setDate(currentDate.getDate() + 1);
+  }
+
+  // Close final phase
+  events.push(createPhaseEvent(currentPhase, phaseStartDate, currentDate));
+
+  const { value, error } = createEvents(events);
+  if (error) {
+    throw new Error(`ICS generation error: ${error}`);
+  }
+
+  return value || "";
+}
+
+function createPhaseEvent(
+  phase: string,
+  startDate: Date,
+  endDate: Date,
+): EventAttributes {
+  const config = PHASE_CONFIGS.find((c) => c.name === phase);
+  const emoji = PHASE_EMOJIS[phase] || "📅";
+
+  return {
+    start: dateToArray(startDate),
+    end: dateToArray(endDate),
+    title: `${emoji} ${phase.replace("_", " ")}`,
+    description: config?.trainingType || "",
+  };
+}
+
+function dateToArray(date: Date): [number, number, number, number, number] {
+  return [date.getFullYear(), date.getMonth() + 1, date.getDate(), 0, 0];
+}

src/lib/nutrition.ts

@@ -0,0 +1,44 @@
+// ABOUTME: Nutrition guidance based on cycle day.
+// ABOUTME: Provides seed cycling and macro recommendations by phase.
+import type { NutritionGuidance } from "@/types";
+
+export function getNutritionGuidance(cycleDay: number): NutritionGuidance {
+  // Seed cycling
+  const seeds =
+    cycleDay <= 14
+      ? "Flax (1-2 tbsp) + Pumpkin (1-2 tbsp)"
+      : "Sesame (1-2 tbsp) + Sunflower (1-2 tbsp)";
+
+  // Macro guidance by day range
+  let carbRange: string;
+  let ketoGuidance: string;
+
+  if (cycleDay >= 1 && cycleDay <= 3) {
+    carbRange = "100-150g";
+    ketoGuidance = "No - body needs carbs during menstruation";
+  } else if (cycleDay >= 4 && cycleDay <= 6) {
+    carbRange = "75-100g";
+    ketoGuidance = "No - transition phase";
+  } else if (cycleDay >= 7 && cycleDay <= 14) {
+    carbRange = "20-100g";
+    ketoGuidance = "OPTIONAL - optimal keto window";
+  } else if (cycleDay >= 15 && cycleDay <= 16) {
+    carbRange = "100-150g";
+    ketoGuidance = "No - exit keto, need carbs for ovulation";
+  } else if (cycleDay >= 17 && cycleDay <= 24) {
+    carbRange = "75-125g";
+    ketoGuidance = "No - progesterone needs carbs";
+  } else {
+    carbRange = "100-150g+";
+    ketoGuidance = "NEVER - mood/hormones need carbs for PMS";
+  }
+
+  return { seeds, carbRange, ketoGuidance };
+}
+
+export function getSeedSwitchAlert(cycleDay: number): string | null {
+  if (cycleDay === 15) {
+    return "🌱 SWITCH TODAY! Start Sesame + Sunflower";
+  }
+  return null;
+}

src/lib/pocketbase.ts

@@ -0,0 +1,10 @@
+// ABOUTME: PocketBase client initialization and utilities.
+// ABOUTME: Provides typed access to the PocketBase backend for auth and data.
+import PocketBase from "pocketbase";
+
+const POCKETBASE_URL = process.env.POCKETBASE_URL || "http://localhost:8090";
+
+export const pb = new PocketBase(POCKETBASE_URL);
+
+// Disable auto-cancellation for server-side usage
+pb.autoCancellation(false);

src/lib/utils.ts

@@ -0,0 +1,8 @@
+// ABOUTME: Utility functions for className merging with Tailwind CSS.
+// ABOUTME: Provides cn() helper for combining conditional class names.
+import { type ClassValue, clsx } from "clsx";
+import { twMerge } from "tailwind-merge";
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs));
+}

src/types/index.ts

@@ -0,0 +1,103 @@
+// ABOUTME: Central type definitions for the PhaseFlow application.
+// ABOUTME: Contains interfaces for users, daily logs, decisions, and cycle data.
+
+export type CyclePhase =
+  | "MENSTRUAL"
+  | "FOLLICULAR"
+  | "OVULATION"
+  | "EARLY_LUTEAL"
+  | "LATE_LUTEAL";
+
+export type HrvStatus = "Balanced" | "Unbalanced" | "Unknown";
+
+export type DecisionStatus = "REST" | "GENTLE" | "LIGHT" | "REDUCED" | "TRAIN";
+
+export type OverrideType = "flare" | "stress" | "sleep" | "pms";
+
+export interface User {
+  id: string;
+  email: string;
+
+  // Garmin
+  garminConnected: boolean;
+  garminOauth1Token: string; // encrypted JSON
+  garminOauth2Token: string; // encrypted JSON
+  garminTokenExpiresAt: Date;
+
+  // Calendar
+  calendarToken: string; // random secret for ICS URL
+
+  // Cycle
+  lastPeriodDate: Date;
+  cycleLength: number; // default: 31
+
+  // Preferences
+  notificationTime: string; // "07:00"
+  timezone: string;
+
+  // Overrides
+  activeOverrides: OverrideType[];
+
+  created: Date;
+  updated: Date;
+}
+
+export interface DailyLog {
+  id: string;
+  user: string; // relation
+  date: Date;
+  cycleDay: number;
+  phase: CyclePhase;
+  bodyBatteryCurrent: number | null;
+  bodyBatteryYesterdayLow: number | null;
+  hrvStatus: HrvStatus;
+  weekIntensityMinutes: number;
+  phaseLimit: number;
+  remainingMinutes: number;
+  trainingDecision: string;
+  decisionReason: string;
+  notificationSentAt: Date | null;
+  created: Date;
+}
+
+export interface PeriodLog {
+  id: string;
+  user: string; // relation
+  startDate: Date;
+  created: Date;
+}
+
+export interface Decision {
+  status: DecisionStatus;
+  reason: string;
+  icon: string;
+}
+
+export interface DailyData {
+  hrvStatus: HrvStatus;
+  bbYesterdayLow: number;
+  phase: CyclePhase;
+  weekIntensity: number;
+  phaseLimit: number;
+  bbCurrent: number;
+}
+
+export interface GarminTokens {
+  oauth1: string;
+  oauth2: string;
+  expires_at: string;
+}
+
+export interface PhaseConfig {
+  name: CyclePhase;
+  days: [number, number]; // start and end day
+  weeklyLimit: number;
+  dailyAvg: number;
+  trainingType: string;
+}
+
+export interface NutritionGuidance {
+  seeds: string;
+  carbRange: string;
+  ketoGuidance: string;
+}