feedkit: split the former maximumdirect.net/weatherd project in two.

feedkit now contains a reusable core, while weatherfeeder is a concrete implementation that includes weather-specific functions.

sinks/stdout.go

@@ -0,0 +1,36 @@
+package sinks
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type StdoutSink struct{ name string }
+
+func NewStdoutSink(name string) *StdoutSink {
+	return &StdoutSink{name: name}
+}
+
+func (s *StdoutSink) Name() string { return s.name }
+
+func (s *StdoutSink) Consume(ctx context.Context, e event.Event) error {
+	_ = ctx
+
+	// Boundary validation: if something upstream violated invariants,
+	// surface it loudly rather than printing partial nonsense.
+	if err := e.Validate(); err != nil {
+		return fmt.Errorf("stdout sink: invalid event: %w", err)
+	}
+
+	// Generic default: one JSON line per event.
+	// This makes stdout useful across all domains and easy to pipe into jq / logs.
+	b, err := json.Marshal(e)
+	if err != nil {
+		return fmt.Errorf("stdout sink: marshal event: %w", err)
+	}
+	fmt.Println(string(b))
+	return nil
+}