Skill: Exporter

Parent: AGENTS.md | Related: backend-service, idevice

When to Use

Adding or modifying export formats in src/shared/export/.

Key Files

• src/shared/export/exporters/BaseExporter.ts — abstract base class (extend this)
• src/shared/export/exporters/Html5Exporter.ts — reference implementation
• src/shared/export/exporters/*.ts — Html5, Scorm12, Scorm2004, Ims, Epub3, Elpx, Component, Page, PrintPreview
• src/shared/export/renderers/ — PageRenderer.ts, IdeviceRenderer.ts
• src/shared/export/generators/ — OdeXmlGenerator.ts, manifest generators, LomMetadata.ts, I18nGenerator.ts
• src/shared/export/providers/ — asset and resource providers
• src/shared/export/adapters/ — YjsDocumentAdapter.ts, BrowserAssetProvider.ts, ExportAssetResolver.ts
• src/shared/export/browser/ — browser-side shims for shared code
• src/shared/export/utils/ — LibraryDetector.ts, GlobalFontGenerator.ts
• public/preview-sw.js — Service Worker for preview

Architecture

Browser (primary path)                    Server (CLI/API only)
─────────────────────                     ─────────────────────
SharedExporters → ZIP in memory           POST /api/export/:sessionId/:type
 → download (web) / save (Electron)       → Y.Doc from DB → exporters → ZIP → stream

The primary export path is browser-side. Server-side export exists only for CLI commands and the external API.

• generateForPreview() — generates files in memory, sends to Service Worker via postMessage
• generate() — full export with ZIP creation

Memory Considerations

Large projects (150MB+) can cause OOM during export. Key patterns (example: PR #1527):

• Chunked base64 conversion — never convert large blobs to base64 in one shot.
• Sequential asset processing — process assets one at a time, not all in parallel.
• Metadata-only listing — use lightweight metadata APIs instead of loading full asset content.

Use the built-in profiling flags to diagnose issues before adding ad-hoc logging:

window.eXeLearning.config.debugElpxExport = true;
// After export: window.__lastElpxExportSummary

Commands

bun test src/shared/export/exporters/MyExporter.spec.ts     # Single test
bun test src/shared/export/                                  # All export tests
make fix                                                     # Lint

Gotchas

• Browser-first architecture — the exporter must work in the browser. Server-side is the secondary path.
• JSZip for extraction, Archiver for creation — don't mix them up. Always check zipEntry.dir before reading content.
• Test both generate() and generateForPreview() — they have different code paths (ZIP vs in-memory files).
• Browser adapter required — if your exporter needs browser APIs, create a shim in src/shared/export/browser/.
• IdeviceRenderer wrapper divs — <div class="exe-text"> wrappers accumulate on re-import. Normalize during import, not during export. Example: PR #1559.
• Library detection — if the exported content uses MathJax or other libraries, LibraryDetector must find them. Tests should verify no 404s for library resources.
• Preview resource loading — preview must not tolerate missing resources. MathJax loads from /app/common/exe_math/tex-mml-svg.js (bypasses the Service Worker when addMathJax: true). Other libraries are detected by LibraryDetector, fetched by ResourceFetcher, and served by the Service Worker. Verify no 404s in preview flows when touching export or resource detection.

Done When

• Extends BaseExporter
• .spec.ts colocated and passing at 90%+ coverage
• Both generate() and generateForPreview() tested
• Browser adapter created if needed (src/shared/export/browser/)
• Large-file scenario considered (no O(n^2) conversions)
• make fix passes clean