feat: migrate to golang

internal/model/time.go

@@ -0,0 +1,62 @@
+package model
+
+import (
+	"fmt"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+// timeLayouts are tried in order when parsing a persisted timestamp. The
+// first two cover what this Go implementation itself writes (time zone
+// aware); the rest cover what the original Python implementation wrote via
+// datetime.now().isoformat() — no time zone, and microseconds included only
+// when non-zero (Go's parser accepts an optional fractional-seconds suffix
+// even when the layout doesn't specify one, so a single no-fraction layout
+// handles both cases).
+var timeLayouts = []string{
+	time.RFC3339Nano,
+	time.RFC3339,
+	"2006-01-02T15:04:05",
+}
+
+// Time wraps time.Time to support reading timestamps in both this Go
+// implementation's own format and the original Python implementation's
+// timezone-naive datetime.isoformat() format (e.g.
+// "2026-03-19T18:21:47.740090"), which Go's default time.Time YAML/text
+// decoding rejects outright since it strictly requires RFC3339 (with a zone
+// offset).
+type Time struct {
+	time.Time
+}
+
+// UnmarshalYAML tries each supported layout in turn.
+func (t *Time) UnmarshalYAML(value *yaml.Node) error {
+	var s string
+	if err := value.Decode(&s); err != nil {
+		return err
+	}
+	if s == "" {
+		t.Time = time.Time{}
+		return nil
+	}
+
+	var lastErr error
+	for _, layout := range timeLayouts {
+		parsed, err := time.Parse(layout, s)
+		if err == nil {
+			t.Time = parsed
+			return nil
+		}
+		lastErr = err
+	}
+	return fmt.Errorf("cannot parse time %q: %w", s, lastErr)
+}
+
+// MarshalYAML writes the timestamp in RFC3339Nano (timezone-aware) format.
+func (t Time) MarshalYAML() (interface{}, error) {
+	if t.Time.IsZero() {
+		return nil, nil
+	}
+	return t.Time.Format(time.RFC3339Nano), nil
+}