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

docs/exploration/chart-theming-scope.md

@@ -171,10 +171,17 @@ ships, it is an explicit per-font user action, never automatic.
    one file drives the whole weight range — only weight/width survive Vega's text rendering
    (no `font-variation-settings` hook). No `CustomTheme.fonts` field: a used face is derived
    by scanning configs/specs (`collectFontFamilies`) — the config is the
-   source of truth, and snippets use fonts with no theme to carry a field. Not done here:
-   embedding font bytes into the §08 export + SVG export (shared base64 machinery, with item 7).
-7. **Deferred** — Google Fonts opt-in tier; SVG export font embedding (+ §08 font-byte
-   round-trip, shared machinery); built-in expressive preset gallery ("Editorial",
+   source of truth, and snippets use fonts with no theme to carry a field.
+7. **Font export round-trip** ✅ (2026-06-16) — uploaded faces travel base64-encoded in the
+   §08 envelope (additive `fonts` array, decoded on import, **skipped** on family clash so a
+   self-backup doesn't pile up copies, rolled back with the rest on a failed import, registered
+   live so they render without reload), and the per-chart **SVG export embeds** the referenced
+   uploaded faces as `@font-face` data-URIs so an exported vector renders the right type off-app.
+   Shared base64 + `fontDataUri`/`primaryFamilyName`/`serializeFontAsset` machinery in
+   `core/font-asset.ts`; SVG embed + family-matching in `core/chart-export.ts`. Roster and
+   system stacks are never embedded (decoration with their own fallbacks; their bytes aren't in
+   the font library).
+8. **Deferred** — Google Fonts opt-in tier; built-in expressive preset gallery ("Editorial",
    "Terminal", "Sketch") showcasing the roster.
 
 **Rejected:** per-snippet theme field (2026-06-12 — `spec.config` + merge/extract covers
@@ -234,6 +241,20 @@ the app standardizes on v6.
 
 ## 6. Status log
 
+- **2026-06-16 (slice 7)** — **font export round-trip + SVG embed.** Uploaded faces now
+  survive a workspace transfer and travel inside an exported SVG. Core: `serializeFontAsset`/
+  `deserializeFontAsset` (+ base64 helpers), `primaryFamilyName`, and `fontDataUri` in
+  `font-asset.ts`; the §08 envelope grew an additive `fonts` array (`export-envelope.ts`),
+  `normalizeImport` decodes it, and a new `dropClashingFonts` enforces the skip-on-clash merge
+  rule (`import-normalize.ts`). Service: `transfer.ts` exports all library fonts, and import
+  dedupes by family, commits fonts in the pre-snippet phase (rolled back with datasets/themes on
+  a failed snippet write), and registers the new faces on success. SVG: `referencedUploadedFonts`
+  - `embedFontsInSvg` in `chart-export.ts`, wired through the renderer's `toImageURL('svg')` with
+    the referenced faces resolved in LivePreview's `getImageUrl` (config captured per render).
+    Decision (font clash): **skip, not rename** — a font is identified by its family (the key in
+    config slots), so an existing same-named face satisfies the reference, and a self-backup
+    doesn't accrete "Font 2" copies; recorded in spec §08 → Name conflicts. Verified: typecheck,
+    lint, full tests. Remaining in §4: Google Fonts opt-in tier; preset gallery.
 - **2026-06-16 (slice 6)** — **user font upload + variable-font weight support.** New
   `FontAsset` entity (instance #4 of the entity-store kind, confirmed by an eng-council
   pre-build consult): `fonts` store @ DB v3, adapter/migration, `FontStore`,