Feat v0.9.2 Starlark converter consolidation + snapshot cleanup (#75)

Consolidate duplicate Go↔Starlark converters into sandbox/convert.go
and snapshot parsers into models/snapshot.go. Standardize snapshot
creation on wrapped format. Net -393 lines across 21 files.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/sandbox/files_module.go

@@ -164,7 +164,7 @@ func filesGet(ctx context.Context, cfg FilesModuleConfig) func(*starlark.Thread,
 			metaRC.Close()
 			var m map[string]any
 			if json.Unmarshal(metaBytes, &m) == nil {
-				metaDict = mapToStarlarkDict(m)
+				metaDict = MapToDict(m)
 			}
 		}
 
@@ -207,7 +207,7 @@ func filesMeta(ctx context.Context, cfg FilesModuleConfig) func(*starlark.Thread
 			metaRC.Close()
 			var m map[string]any
 			if json.Unmarshal(metaBytes, &m) == nil {
-				metaDict = mapToStarlarkDict(m)
+				metaDict = MapToDict(m)
 			}
 		}
 
@@ -396,77 +396,13 @@ func filesMaxSize() int64 {
 	return filesDefaultMaxSize
 }
 
-// starlarkDictToMap converts a *starlark.Dict to map[string]any.
+// starlarkDictToMap converts a *starlark.Dict to map[string]any, validating
+// that all keys are strings.  Returns an error if a non-string key is found.
 func starlarkDictToMap(d *starlark.Dict) (map[string]any, error) {
-	m := make(map[string]any, d.Len())
 	for _, item := range d.Items() {
-		k, ok := starlark.AsString(item[0])
-		if !ok {
+		if _, ok := starlark.AsString(item[0]); !ok {
 			return nil, fmt.Errorf("metadata keys must be strings, got %s", item[0].Type())
 		}
-		m[k] = starlarkValueToGo(item[1])
-	}
-	return m, nil
-}
-
-// starlarkValueToGo converts a starlark.Value to a Go value for JSON serialization.
-func starlarkValueToGo(v starlark.Value) any {
-	switch x := v.(type) {
-	case starlark.String:
-		return string(x)
-	case starlark.Int:
-		if i, ok := x.Int64(); ok {
-			return i
-		}
-		return x.String()
-	case starlark.Float:
-		return float64(x)
-	case starlark.Bool:
-		return bool(x)
-	case *starlark.List:
-		out := make([]any, x.Len())
-		for i := 0; i < x.Len(); i++ {
-			out[i] = starlarkValueToGo(x.Index(i))
-		}
-		return out
-	case *starlark.Dict:
-		m, _ := starlarkDictToMap(x)
-		return m
-	default:
-		return v.String()
-	}
-}
-
-// mapToStarlarkDict converts a map[string]any to *starlark.Dict.
-func mapToStarlarkDict(m map[string]any) *starlark.Dict {
-	d := starlark.NewDict(len(m))
-	for k, v := range m {
-		d.SetKey(starlark.String(k), goValueToStarlark(v))
-	}
-	return d
-}
-
-// goValueToStarlark converts a Go value (from JSON) to starlark.Value.
-func goValueToStarlark(v any) starlark.Value {
-	switch x := v.(type) {
-	case string:
-		return starlark.String(x)
-	case float64:
-		if x == float64(int64(x)) {
-			return starlark.MakeInt64(int64(x))
-		}
-		return starlark.Float(x)
-	case bool:
-		return starlark.Bool(x)
-	case []any:
-		elems := make([]starlark.Value, len(x))
-		for i, e := range x {
-			elems[i] = goValueToStarlark(e)
-		}
-		return starlark.NewList(elems)
-	case map[string]any:
-		return mapToStarlarkDict(x)
-	default:
-		return starlark.None
 	}
+	return DictToMap(d), nil
 }