io / proto-editor-meta

src/io/proto/editorMeta.ts reads and writes Apollo Map's editor_meta field (proto field number 1000). This is a custom extension Apollo Map Studio uses to persist editor-only hints (e.g. "this entity is a closed polygon, not a polyline"). Apollo runtime ignores the field; proto2's preserve-unknown-fields semantics keep it across round-trip, so a single .bin works in both worlds.

Exported symbols

export type EditorGeometryKind = 'LINESTRING' | 'POLYGON';

export interface EditorEntityMeta {
  geometryKind?: EditorGeometryKind;
}

export interface EditorMeta {
  version: number;
  entity: Record<string, EditorEntityMeta>;
}

export const EDITOR_META_VERSION: 1;

export function readEditorMeta(rawMap: Record<string, unknown>): EditorMeta;
export function writeEditorMeta(rawMap: Record<string, unknown>, meta: EditorMeta): void;
export function entityKey(entityType: string, id: string): string;

Source: src/io/proto/editorMeta.ts:1-84.

Wire format

message EditorMeta {
  optional uint32 version = 1;
  map<string, EditorEntityMeta> entity = 2;
}
message EditorEntityMeta {
  optional EditorGeometryKind geometry_kind = 1;
}
enum EditorGeometryKind {
  EDITOR_GEOMETRY_KIND_UNSPECIFIED = 0;
  LINESTRING = 1;
  POLYGON = 2;
}

read / write translate between the editor's camelCase + string enum form and the wire's keepCase: true snake_case + numeric enum form.

readEditorMeta(rawMap)

Returns { version, entity }. Missing editor_meta falls back to { version: EDITOR_META_VERSION, entity: {} }. Unknown geometry_kind numerics are silently dropped.

writeEditorMeta(rawMap, meta)

Sets rawMap.editor_meta = wire. encodeEntity does not emit geometry_kind: 0 when geometryKind is unset, preserving wire fidelity.

entityKey(entityType, id)

return `${entityType}:${id}`;

Two entities with the same id but different types do not collide because the key bakes both in.

Workflow

Limitations

• Today only geometryKind is supported. Adding new fields requires bumping EDITOR_META_VERSION and providing forward-compat handling in readEditorMeta.
• Importing legacy Apollo .bin files without editor_meta defaults wire.version to EDITOR_META_VERSION.
• Apollo runtime ignores the field — safe to leave in production builds.

See also

• Proto / Schema — schema layout, including editor/editor_meta.proto.
• io/map-io — entry that triggers readEditorMeta after import and writeEditorMeta before export.

Contributors

kent

Changelog

Last edited 4 minutes ago

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8d55547-test(e2e): run the full playwright suite