feat(06-03): add wire JSON helpers, Time, TriBool, and Slice

- WriteJSON matches genre_controller byte-for-byte (SetEscapeHTML false, trim trailing newline)
- Time marshals Carbon +00:00 never Z; TriBool nulls when invalid; Slice never returns nil

wire/response.go

@@ -0,0 +1,90 @@
+package wire
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"time"
+)
+
+// WriteJSON encodes v as JSON with HTML escaping disabled and no trailing
+// newline, matching the PHP json_encode body shape used by house handlers.
+func WriteJSON(w http.ResponseWriter, status int, v any) {
+	var buf bytes.Buffer
+	enc := json.NewEncoder(&buf)
+	enc.SetEscapeHTML(false)
+	if err := enc.Encode(v); err != nil {
+		WriteOpaque500(w)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_, _ = w.Write(bytes.TrimSuffix(buf.Bytes(), []byte("\n")))
+}
+
+// WriteOpaque500 writes the house opaque 500 body.
+func WriteOpaque500(w http.ResponseWriter) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusInternalServerError)
+	_, _ = w.Write([]byte(`{"error":true,"message":"Internal server error"}`))
+}
+
+// Time marshals as Carbon's +00:00 form (2006-01-02T15:04:05+00:00), never
+// Go's default "Z". Unmarshal accepts both +00:00 and Z for read paths.
+type Time struct{ time.Time }
+
+const (
+	carbonLayout = "2006-01-02T15:04:05-07:00"
+	rfc3339Z     = time.RFC3339
+)
+
+func (t Time) MarshalJSON() ([]byte, error) {
+	s := t.UTC().Format("2006-01-02T15:04:05") + "+00:00"
+	return []byte(`"` + s + `"`), nil
+}
+
+func (t *Time) UnmarshalJSON(b []byte) error {
+	if t == nil {
+		return nil
+	}
+	if string(b) == "null" {
+		t.Time = time.Time{}
+		return nil
+	}
+	var s string
+	if err := json.Unmarshal(b, &s); err != nil {
+		return err
+	}
+	var err error
+	for _, layout := range []string{carbonLayout, rfc3339Z} {
+		var parsed time.Time
+		parsed, err = time.Parse(layout, s)
+		if err == nil {
+			t.Time = parsed
+			return nil
+		}
+	}
+	return err
+}
+
+// TriBool keeps PHP's nullable-boolean tri-state: Valid=false marshals null.
+type TriBool struct{ Valid, Value bool }
+
+func (b TriBool) MarshalJSON() ([]byte, error) {
+	if !b.Valid {
+		return []byte("null"), nil
+	}
+	if b.Value {
+		return []byte("true"), nil
+	}
+	return []byte("false"), nil
+}
+
+// Slice returns s unchanged if non-nil, else a non-nil empty slice that
+// marshals to [].
+func Slice[T any](s []T) []T {
+	if s == nil {
+		return []T{}
+	}
+	return s
+}

wire/response_test.go

@@ -0,0 +1,113 @@
+package wire
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"regexp"
+	"testing"
+	"time"
+)
+
+// carbonOffsetRe is tide/normalize.go's Carbon +00:00 form, copied so wire
+// does not import tide.
+var carbonOffsetRe = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\+00:00$`)
+
+func TestTimeMarshalJSONCarbonOffset(t *testing.T) {
+	tm := Time{Time: time.Date(2024, 1, 2, 3, 4, 5, 0, time.UTC)}
+	b, err := json.Marshal(tm)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var s string
+	if err := json.Unmarshal(b, &s); err != nil {
+		t.Fatal(err)
+	}
+	if !carbonOffsetRe.MatchString(s) {
+		t.Fatalf("got %q, want carbon +00:00 form", s)
+	}
+	if string(b) != `"2024-01-02T03:04:05+00:00"` {
+		t.Fatalf("bytes = %s", b)
+	}
+}
+
+func TestTimeUnmarshalJSONAcceptsOffsetAndZ(t *testing.T) {
+	var offset Time
+	if err := json.Unmarshal([]byte(`"2024-01-02T03:04:05+00:00"`), &offset); err != nil {
+		t.Fatal(err)
+	}
+	if !offset.Equal(time.Date(2024, 1, 2, 3, 4, 5, 0, time.UTC)) {
+		t.Fatalf("offset = %v", offset.Time)
+	}
+	var z Time
+	if err := json.Unmarshal([]byte(`"2024-01-02T03:04:05Z"`), &z); err != nil {
+		t.Fatal(err)
+	}
+	if !z.Equal(time.Date(2024, 1, 2, 3, 4, 5, 0, time.UTC)) {
+		t.Fatalf("z = %v", z.Time)
+	}
+}
+
+func TestTriBoolMarshalJSON(t *testing.T) {
+	null, err := json.Marshal(TriBool{Valid: false})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(null) != "null" {
+		t.Fatalf("invalid = %s", null)
+	}
+	f, err := json.Marshal(TriBool{Valid: true, Value: false})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(f) != "false" {
+		t.Fatalf("false = %s", f)
+	}
+	tr, err := json.Marshal(TriBool{Valid: true, Value: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(tr) != "true" {
+		t.Fatalf("true = %s", tr)
+	}
+}
+
+func TestSliceNilMarshalsEmptyArray(t *testing.T) {
+	s := Slice[int](nil)
+	if s == nil {
+		t.Fatal("Slice(nil) returned nil")
+	}
+	b, err := json.Marshal(s)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(b) != "[]" {
+		t.Fatalf("got %s", b)
+	}
+}
+
+func TestWriteJSONNoHTMLEscapeNoTrailingNewline(t *testing.T) {
+	rec := httptest.NewRecorder()
+	WriteJSON(rec, http.StatusOK, map[string]string{"a": "x<y"})
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d", rec.Code)
+	}
+	got := rec.Body.String()
+	if got != `{"a":"x<y"}` {
+		t.Fatalf("body = %q", got)
+	}
+	if rec.Header().Get("Content-Type") != "application/json" {
+		t.Fatalf("Content-Type = %q", rec.Header().Get("Content-Type"))
+	}
+}
+
+func TestWriteOpaque500(t *testing.T) {
+	rec := httptest.NewRecorder()
+	WriteOpaque500(rec)
+	if rec.Code != http.StatusInternalServerError {
+		t.Fatalf("status = %d", rec.Code)
+	}
+	if rec.Body.String() != `{"error":true,"message":"Internal server error"}` {
+		t.Fatalf("body = %q", rec.Body.String())
+	}
+}