feat: workout-suggester, weather-aware workouts from a local Gemma

Go + Templ + HTMX app that checks the weather (Open-Meteo, MET Norway
fallback), scores run/ride/walk with plain rules, and has a local
open-weight model (Gemma 4 E2B via any OpenAI-compatible server) write
the plan. Routes are loops from your door (BRouter) plus signposted
OpenStreetMap routes (Overpass), with GPX export.

internal/coach/coach_test.go

@@ -0,0 +1,144 @@
+package coach
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"git.b0b.be/bdeb/workout-suggester/internal/weather"
+)
+
+// forecast builds a 24-hour forecast where every hour looks like h, then
+// lets the test tweak individual hours.
+func forecast(h weather.Hour, tweak func(i int, h *weather.Hour)) weather.Forecast {
+	start := time.Date(2026, 10, 11, 14, 0, 0, 0, time.UTC)
+	f := weather.Forecast{Sunset: start.Add(5 * time.Hour)}
+	for i := range 24 {
+		x := h
+		x.Time = start.Add(time.Duration(i) * time.Hour)
+		x.IsDay = i < 5
+		if tweak != nil {
+			tweak(i, &x)
+		}
+		f.Hours = append(f.Hours, x)
+	}
+	f.Now = f.Hours[0]
+	return f
+}
+
+var nice = weather.Hour{Temp: 15, Feels: 14, Wind: 10, Gusts: 20, Code: 1}
+
+func TestAssess(t *testing.T) {
+	tests := []struct {
+		name  string
+		f     weather.Forecast
+		req   Request
+		pick  Activity
+		check func(t *testing.T, a Assessment)
+	}{
+		{
+			name: "nice weather, anything goes",
+			f:    forecast(nice, nil),
+			req:  Request{Intensity: Moderate, Minutes: 60},
+			pick: Run,
+		},
+		{
+			name: "wanted activity is honoured when fine",
+			f:    forecast(nice, nil),
+			req:  Request{Activity: Ride, Intensity: Hard, Minutes: 90},
+			pick: Ride,
+			check: func(t *testing.T, a Assessment) {
+				if a.TargetKm != 42 {
+					t.Errorf("90 min hard ride target = %v km, want 42", a.TargetKm)
+				}
+			},
+		},
+		{
+			name: "windy: running beats cycling",
+			f:    forecast(weather.Hour{Temp: 12, Feels: 9, Wind: 30, Gusts: 50, Code: 3}, nil),
+			req:  Request{Intensity: Moderate, Minutes: 45},
+			pick: Run,
+			check: func(t *testing.T, a Assessment) {
+				if ride, run := a.ScoreOf(Ride).Value, a.ScoreOf(Run).Value; ride >= run {
+					t.Errorf("ride %d should score below run %d in strong gusts", ride, run)
+				}
+			},
+		},
+		{
+			name: "storm sends you inside",
+			f:    forecast(weather.Hour{Temp: 8, Feels: 3, Wind: 40, Gusts: 70, Precip: 3, PrecipProb: 95, Code: 63}, nil),
+			req:  Request{Activity: Run, Intensity: Moderate, Minutes: 60},
+			pick: Indoor,
+		},
+		{
+			name: "thunder is a hard no",
+			f:    forecast(weather.Hour{Temp: 22, Feels: 22, Code: 95}, nil),
+			req:  Request{Intensity: Easy, Minutes: 30},
+			pick: Indoor,
+		},
+		{
+			name: "rain now, dry later: suggests the later window",
+			f: forecast(nice, func(i int, h *weather.Hour) {
+				if i < 2 {
+					h.Precip, h.PrecipProb, h.Code = 3, 90, 63
+				}
+			}),
+			req:  Request{Activity: Ride, Intensity: Moderate, Minutes: 60},
+			pick: Indoor,
+			check: func(t *testing.T, a Assessment) {
+				if a.Later == nil || a.Later.Start.Hour() != 16 || a.Later.Activity != Ride {
+					t.Errorf("later = %+v, want a ride at 16:00", a.Later)
+				}
+			},
+		},
+		{
+			name: "hard intensity doesn't pick a stroll",
+			f:    forecast(weather.Hour{Temp: 15, Feels: 14, Wind: 10, Gusts: 20, Precip: 0.6, Code: 61}, nil),
+			req:  Request{Intensity: Hard, Minutes: 60},
+			pick: Run,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := Assess(tt.f, tt.req)
+			if a.Pick != tt.pick {
+				t.Errorf("pick = %s, want %s (scores %+v)", a.Pick, tt.pick, a.Scores)
+			}
+			if tt.check != nil {
+				tt.check(t, a)
+			}
+		})
+	}
+}
+
+func TestDarkIsMentioned(t *testing.T) {
+	f := forecast(nice, nil)
+	f.Hours = f.Hours[4:] // 18:00, the last daylight hour, then night
+	f.Now = f.Hours[0]
+	s := Assess(f, Request{Intensity: Easy, Minutes: 90}).ScoreOf(Run)
+	if !strings.Contains(strings.Join(s.Reasons, ","), "dark") {
+		t.Errorf("reasons %v should mention the dark", s.Reasons)
+	}
+}
+
+func TestTargetPace(t *testing.T) {
+	km, pace := target(Run, Moderate, 60)
+	if km != 10.5 || pace != "about 5:45 min/km" {
+		t.Errorf("got %v %q", km, pace)
+	}
+	if km, _ := target(Indoor, Hard, 60); km != 0 {
+		t.Errorf("indoor target = %v, want 0", km)
+	}
+}
+
+func TestFactsCarryTheNumbers(t *testing.T) {
+	f := forecast(nice, nil)
+	p := Plan{Place: "Gent", Forecast: f, Request: Request{Intensity: Moderate, Minutes: 60, Note: "sore knee"},
+		Assessment: Assess(f, Request{Intensity: Moderate, Minutes: 60}), RoutesLoaded: true}
+	got := p.SystemPrompt()
+	for _, want := range []string{"Gent", "15°C", "sore knee", "The app's pick: running", "about 10.5 km", "Routes: none found nearby"} {
+		if !strings.Contains(got, want) {
+			t.Errorf("system prompt lacks %q:\n%s", want, got)
+		}
+	}
+}