seatgen writes a date-time as time.Time (a string in TypeScript), by value when required, by pointer when optional (B5d; ADR 0634; issue 1966)

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

modules/mesh-build-go/buildstep/seatgen/gogen.go

@@ -219,6 +219,16 @@ func goWhole(m *Module, d seatdef.Definition) ([]byte, []byte, error) {
 	if err := goTypes(&b, tp, map[string]*typ{}); err != nil {
 		return nil, nil, err
 	}
+	if bytes.Contains(b.Bytes(), []byte("time.Time")) {
+		// A moment is the standard library's time (the only import a contract may have besides its states' readers).
+		raw := b.Bytes()
+		if bytes.Contains(raw, []byte("\nimport (\n")) {
+			raw = bytes.Replace(raw, []byte("\nimport (\n"), []byte("\nimport (\n\t\"time\"\n"), 1)
+		} else {
+			raw = bytes.Replace(raw, []byte("package "+pkg+"\n\n"), []byte("package "+pkg+"\n\nimport \"time\"\n\n"), 1)
+		}
+		b = *bytes.NewBuffer(raw)
+	}
 	src, err := gofmt(&b)
 	if err != nil {
 		return nil, nil, err
@@ -285,6 +295,11 @@ func goType(t *typ, kinds map[string]*typ, required bool) string {
 	switch t.kind {
 	case "string":
 		return "string"
+	case "time":
+		if required {
+			return "time.Time"
+		}
+		return "*time.Time"
 	case "integer":
 		return "int64"
 	case "number":

modules/mesh-build-go/buildstep/seatgen/layout_test.go

@@ -72,6 +72,15 @@ func TestEachSeatDefinedWholeIsAGoModuleOfItsOwn(t *testing.T) {
 		if !strings.Contains(src, "type Ref struct") || !strings.Contains(src, "type PublishedEvent") {
 			t.Errorf("%s does not hold the part's types whole", seat)
 		}
+		// A moment (format date-time) is the standard library's time in Go, a required one by value and an optional one
+		// by pointer (a zero time is not an absent one), and a string in TypeScript.
+		if !re.MustCompile(`Pushed\s+time\.Time\s+`+"`json:\"pushed\"`").MatchString(src) || !re.MustCompile(`At\s+\*time\.Time\s+`+"`json:\"at,omitempty\"`").MatchString(src) ||
+			!(strings.Contains(src, "\t\"time\"\n") || strings.Contains(src, "import \"time\"")) {
+			t.Errorf("%s does not write a date-time as time.Time:\n%s", seat, src)
+		}
+		if ts := string(files["ts/seats/"+seat+"/src/parts/registry.ts"]); !strings.Contains(ts, `"pushed": string;`) || !strings.Contains(ts, `"at"?: string;`) {
+			t.Errorf("%s's TypeScript does not write a date-time as a string:\n%s", seat, ts)
+		}
 		// A string's enum is a constant per value, so a caller names the definition's value (A3t: the removal reason).
 		if !re.MustCompile(`RefReasonRetention\s+= "retention"`).MatchString(src) || !re.MustCompile(`RefReasonTagGone\s+= "tag-gone"`).MatchString(src) {
 			t.Errorf("%s does not name the part's enum values:\n%s", seat, src)

modules/mesh-build-go/buildstep/seatgen/testdata/contracts/parts/registry.json

@@ -1,3 +1,3 @@
 {"format":1,"part":"registry","verbs":[{"name":"publish","input":{"$ref":"#/defs/Ref"},"answer":{"type":"object"}}],
  "events":[{"name":"published","body":{"$ref":"#/defs/Ref"}}],
- "defs":{"Ref":{"type":"object","properties":{"digest":{"type":"string"},"reason":{"type":"string","enum":["tag-gone","retention"]}},"required":["digest"]}}}
+ "defs":{"Ref":{"type":"object","properties":{"digest":{"type":"string"},"at":{"type":"string","format":"date-time"},"pushed":{"type":"string","format":"date-time"},"reason":{"type":"string","enum":["tag-gone","retention"]}},"required":["digest","pushed"]}}}

modules/mesh-build-go/buildstep/seatgen/tsgen.go

@@ -204,6 +204,8 @@ func tsType(t *typ) string {
 			return strings.Join(parts, " | ")
 		}
 		return "string"
+	case "time":
+		return "string"
 	case "integer", "number":
 		return "number"
 	case "boolean":

modules/mesh-build-go/buildstep/seatgen/types.go

@@ -10,7 +10,7 @@ import (
 // properties, maps, arrays, strings, integers, numbers, booleans, references to a definition's own types). Anything
 // else is `any`, so a schema the generator does not understand still decodes.
 type typ struct {
-	kind   string // string, integer, number, boolean, any, map, slice, struct, ref, object (free)
+	kind   string // string, time (a string of format date-time), integer, number, boolean, any, map, slice, struct, ref, object (free)
 	elem   *typ   // a map's value or a slice's item
 	ref    string // a referenced type's name
 	fields []field
@@ -71,6 +71,10 @@ func (tp *typer) read(where string, s map[string]any, top bool) (*typ, error) {
 	switch t {
 	case "string":
 		out := &typ{kind: "string"}
+		if f, _ := s["format"].(string); f == "date-time" {
+			// A moment: Go writes time.Time (RFC 3339 on the wire), TypeScript the string (ADR 0634).
+			return &typ{kind: "time"}, nil
+		}
 		if e, ok := s["enum"].([]any); ok {
 			for _, v := range e {
 				if str, ok := v.(string); ok {