Seed from go-template-repo, renamed to simplexcalc

The template's files at a77fd30, without its history or LICENSE, after
script/rename simplexcalc.

Model: opus-5-5

internal/app/app.go

@@ -0,0 +1,72 @@
+// Package app wires the object graph. It is the one place that knows
+// which concrete types satisfy the application's dependencies, so every
+// other package can be constructed in a test with substitutes.
+package app
+
+import (
+	"log/slog"
+
+	"go.uber.org/fx"
+	"go.uber.org/fx/fxevent"
+	"sneak.berlin/go/simplexcalc/internal/config"
+	"sneak.berlin/go/simplexcalc/internal/database"
+	"sneak.berlin/go/simplexcalc/internal/globals"
+	"sneak.berlin/go/simplexcalc/internal/handlers"
+	"sneak.berlin/go/simplexcalc/internal/logger"
+	"sneak.berlin/go/simplexcalc/internal/middleware"
+	"sneak.berlin/go/simplexcalc/internal/render"
+	"sneak.berlin/go/simplexcalc/internal/server"
+	"sneak.berlin/go/simplexcalc/internal/telemetry"
+)
+
+// Module is every provider the service needs. Constructor order is
+// irrelevant to fx; the order here is the order a reader wants: build
+// metadata, logging, configuration, storage, then the HTTP layer.
+//
+//nolint:gochecknoglobals // an fx module is a declaration, not mutable state.
+var Module = fx.Options(
+	fx.Provide(
+		globals.New,
+		logger.New,
+		config.New,
+		database.New,
+		telemetry.NewSentry,
+		telemetry.NewMetrics,
+		render.New,
+		middleware.New,
+		handlers.New,
+		server.New,
+	),
+
+	// fx's own lifecycle events go through the application logger, so
+	// the process emits one stream in one format. Without this, fx
+	// prints its own plain-text output to stderr and a log pipeline
+	// gets two formats from one process.
+	fx.WithLogger(func(l *logger.Logger) fxevent.Logger {
+		return &fxevent.SlogLogger{Logger: l.Get()}
+	}),
+)
+
+// Invoke forces the graph to be built. fx constructs lazily: without a
+// request for the Server, a perfectly valid App would start, construct
+// nothing, and serve nothing.
+//
+//nolint:gochecknoglobals // as above.
+var Invoke = fx.Invoke(func(_ *server.Server, log *logger.Logger, cfg *config.Config) {
+	if cfg.Debug {
+		log.EnableDebugLogging()
+	}
+
+	log.Identify()
+})
+
+// New builds the fx application for `serve`.
+func New(opts ...fx.Option) *fx.App {
+	return fx.New(append([]fx.Option{Module, Invoke}, opts...)...)
+}
+
+// DiscardLogger is a logger that writes nothing, for tests that build
+// the graph and do not want its startup output.
+func DiscardLogger() *slog.Logger {
+	return slog.New(slog.DiscardHandler)
+}