fitness: add kcal estimation based on Lytle et al. (2019) regression model

Estimate strength workout energy expenditure using the Lytle et al. multiple
linear regression model. Maps all 77 exercises to 7 studied categories with
confidence levels. Shows kcal on stats page (cumulative), session cards,
workout detail, and workout completion screen. Supports sex/height demographics
via profile section on measure page. Includes info tooltip with DOI reference.

src/routes/api/fitness/goal/+server.ts

@@ -14,31 +14,36 @@ export const GET: RequestHandler = async ({ locals }) => {
 
 	// If no goal set, return early
 	if (weeklyWorkouts === null) {
-		return json({ weeklyWorkouts: null, streak: 0 });
+		return json({ weeklyWorkouts: null, streak: 0, sex: goal?.sex ?? 'male', heightCm: goal?.heightCm ?? null });
 	}
 
 	const streak = await computeStreak(user.nickname, weeklyWorkouts);
-	return json({ weeklyWorkouts, streak });
+	return json({ weeklyWorkouts, streak, sex: goal?.sex ?? 'male', heightCm: goal?.heightCm ?? null });
 };
 
 export const PUT: RequestHandler = async ({ request, locals }) => {
 	const user = await requireAuth(locals);
-	const { weeklyWorkouts } = await request.json();
+	const body = await request.json();
+	const { weeklyWorkouts, sex, heightCm } = body;
 
 	if (typeof weeklyWorkouts !== 'number' || weeklyWorkouts < 1 || weeklyWorkouts > 14 || !Number.isInteger(weeklyWorkouts)) {
 		return json({ error: 'weeklyWorkouts must be an integer between 1 and 14' }, { status: 400 });
 	}
 
+	const update: Record<string, unknown> = { weeklyWorkouts };
+	if (sex === 'male' || sex === 'female') update.sex = sex;
+	if (typeof heightCm === 'number' && heightCm >= 100 && heightCm <= 250) update.heightCm = heightCm;
+
 	await dbConnect();
 
-	await FitnessGoal.findOneAndUpdate(
+	const goal = await FitnessGoal.findOneAndUpdate(
 		{ username: user.nickname },
-		{ weeklyWorkouts },
-		{ upsert: true }
-	);
+		update,
+		{ upsert: true, new: true }
+	).lean() as any;
 
 	const streak = await computeStreak(user.nickname, weeklyWorkouts);
-	return json({ weeklyWorkouts, streak });
+	return json({ weeklyWorkouts, streak, sex: goal?.sex ?? 'male', heightCm: goal?.heightCm ?? null });
 };
 
 async function computeStreak(username: string, weeklyGoal: number): Promise<number> {

src/routes/api/fitness/stats/overview/+server.ts

@@ -5,6 +5,8 @@ import { dbConnect } from '$utils/db';
 import { WorkoutSession } from '$models/WorkoutSession';
 import { BodyMeasurement } from '$models/BodyMeasurement';
 import { getExerciseById, getExerciseMetrics } from '$lib/data/exercises';
+import { estimateWorkoutKcal, estimateCumulativeKcal, type ExerciseData, type Demographics } from '$lib/data/kcalEstimate';
+import { FitnessGoal } from '$models/FitnessGoal';
 
 export const GET: RequestHandler = async ({ locals }) => {
 	const user = await requireAuth(locals);
@@ -36,7 +38,23 @@ export const GET: RequestHandler = async ({ locals }) => {
 		}
 	]);
 
-	// Lifetime totals: tonnage lifted + cardio km
+	// Fetch user demographics for kcal estimation
+	const [goal, latestMeasurement] = await Promise.all([
+		FitnessGoal.findOne({ username: user.nickname }).lean() as any,
+		BodyMeasurement.findOne(
+			{ createdBy: user.nickname, weight: { $ne: null } },
+			{ weight: 1, bodyFatPercent: 1, _id: 0 }
+		).sort({ date: -1 }).lean() as any
+	]);
+
+	const demographics: Demographics = {
+		heightCm: goal?.heightCm ?? undefined,
+		isMale: (goal?.sex ?? 'male') === 'male',
+		bodyWeightKg: latestMeasurement?.weight ?? undefined,
+		bodyFatPct: latestMeasurement?.bodyFatPercent ?? undefined,
+	};
+
+	// Lifetime totals: tonnage lifted + cardio km + kcal estimate
 	const allSessions = await WorkoutSession.find(
 		{ createdBy: user.nickname },
 		{ 'exercises.exerciseId': 1, 'exercises.sets': 1 }
@@ -44,23 +62,38 @@ export const GET: RequestHandler = async ({ locals }) => {
 
 	let totalTonnage = 0;
 	let totalCardioKm = 0;
+	const workoutKcalResults: { kcal: number; see: number }[] = [];
+
 	for (const s of allSessions) {
+		const strengthExercises: ExerciseData[] = [];
 		for (const ex of s.exercises) {
 			const exercise = getExerciseById(ex.exerciseId);
 			const metrics = getExerciseMetrics(exercise);
 			const isCardio = metrics.includes('distance');
 			const weightMultiplier = exercise?.bilateral ? 2 : 1;
+			const completedSets: { weight: number; reps: number }[] = [];
 			for (const set of ex.sets) {
 				if (!set.completed) continue;
 				if (isCardio) {
 					totalCardioKm += set.distance ?? 0;
 				} else {
-					totalTonnage += (set.weight ?? 0) * weightMultiplier * (set.reps ?? 0);
+					const w = (set.weight ?? 0) * weightMultiplier;
+					totalTonnage += w * (set.reps ?? 0);
+					if (set.reps) completedSets.push({ weight: w, reps: set.reps });
 				}
 			}
+			if (completedSets.length > 0) {
+				strengthExercises.push({ exerciseId: ex.exerciseId, sets: completedSets });
+			}
+		}
+		if (strengthExercises.length > 0) {
+			const result = estimateWorkoutKcal(strengthExercises, demographics);
+			workoutKcalResults.push({ kcal: result.kcal, see: result.see });
 		}
 	}
 
+	const kcalEstimate = estimateCumulativeKcal(workoutKcalResults);
+
 	const weightMeasurements = await BodyMeasurement.find(
 		{ createdBy: user.nickname, weight: { $ne: null } },
 		{ date: 1, weight: 1, _id: 0 }
@@ -141,6 +174,7 @@ export const GET: RequestHandler = async ({ locals }) => {
 		totalWorkouts,
 		totalTonnage: Math.round(totalTonnage / 1000 * 10) / 10,
 		totalCardioKm: Math.round(totalCardioKm * 10) / 10,
+		kcalEstimate,
 		workoutsChart,
 		weightChart
 	});