Fonts: carry uploaded faces through export/import + embed in SVG export

src/core/export-envelope.ts

@@ -14,6 +14,7 @@
 
 import type { CustomTheme } from './custom-theme';
 import type { Dataset } from './dataset';
+import { serializeFontAsset, type FontAsset, type SerializedFontAsset } from './font-asset';
 import type { Snippet } from './snippet';
 
 /**
@@ -26,8 +27,8 @@ export const EXPORT_ENVELOPE_VERSION = '1.0';
 /**
  * The downloaded file's top-level shape (spec §08 → Export envelope shape): format
  * metadata plus the complete-record arrays. Each record keeps its own `version`
- * field unchanged. `themes` is additive (always written, optional on read) so
- * pre-theme envelopes and importers remain compatible without a format bump.
+ * field unchanged. `themes` and `fonts` are additive (always written, optional on
+ * read) so older envelopes and importers remain compatible without a format bump.
  */
 export interface ExportEnvelope {
   /** Export format version (currently `"1.0"`). */
@@ -42,6 +43,13 @@ export interface ExportEnvelope {
   datasets: Dataset[];
   /** All custom chart themes, as complete records (each including its record `version`). */
   themes: CustomTheme[];
+  /**
+   * All uploaded font faces, base64-encoded so a referenced face survives the
+   * round-trip (without this the family name imports but renders as fallback —
+   * spec §08, scope doc §4). The whole library travels, like datasets/themes: a
+   * workspace export is a backup, not a minimal bundle of what's referenced.
+   */
+  fonts: SerializedFontAsset[];
 }
 
 /**
@@ -55,6 +63,7 @@ export function buildExportEnvelope(
   snippets: ReadonlyArray<Snippet>,
   datasets: ReadonlyArray<Dataset>,
   themes: ReadonlyArray<CustomTheme>,
+  fonts: ReadonlyArray<FontAsset>,
   opts: { now: Date },
 ): ExportEnvelope {
   return {
@@ -64,6 +73,8 @@ export function buildExportEnvelope(
     snippets: [...snippets],
     datasets: [...datasets],
     themes: [...themes],
+    // Encode each face's bytes (ArrayBuffer → base64) so the array is JSON-safe.
+    fonts: fonts.map(serializeFontAsset),
   };
 }
 
@@ -90,19 +101,21 @@ function countClause(count: number, noun: string): string {
 /**
  * Success-toast message reporting transfer counts (spec §08 → Feedback) for both
  * directions, e.g. "Exported 4 snippets, 2 datasets and 1 theme" / "Imported 1
- * snippet". The dataset and theme clauses are omitted entirely when their counts
- * are zero; singular/plural wording adapts. One builder for export and import so
- * a new record kind or wording change lands in both messages at once.
+ * snippet". The dataset, theme, and font clauses are omitted entirely when their
+ * counts are zero; singular/plural wording adapts. One builder for export and
+ * import so a new record kind or wording change lands in both messages at once.
  */
 export function transferSummaryMessage(
   verb: 'Exported' | 'Imported',
   snippetCount: number,
   datasetCount: number,
   themeCount: number,
+  fontCount: number,
 ): string {
   const clauses = [countClause(snippetCount, 'snippet')];
   if (datasetCount > 0) clauses.push(countClause(datasetCount, 'dataset'));
   if (themeCount > 0) clauses.push(countClause(themeCount, 'theme'));
+  if (fontCount > 0) clauses.push(countClause(fontCount, 'font'));
   const last = clauses.pop()!;
   return clauses.length === 0 ? `${verb} ${last}` : `${verb} ${clauses.join(', ')} and ${last}`;
 }