@unlayer/migrate: MJML and Beefree importers (--from mjml|beefree)

[ivoIturrieta]

Stacked on the 0.3.0 library PR (#69), since it uses @unlayer/react-elements/codegen: it shows only the importer changes. Merge it after #69, with its base changed to main first (GitHub does that itself when #69's branch is deleted on merge).

The repo's tests only run on pull requests into main, so CI starts here once the base is main (a push after that triggers it). Until then, the validation below was run locally on the branch.

What

npx @unlayer/migrate <dir> --from mjml and --from beefree, with the same flow as --from react-email:

• convert, check against the original, report;
• --write / --out / --design / --report / --strict, the same git-safety and collision rules, the same ✓/✗ output and exit codes.

The source files stay in place, and <name>.tsx is written beside each one.

Both converters are pure source → Unlayer design functions (src/from-mjml, src/from-beefree). The library's codegen writes the design as Elements code, and --design writes the design itself. MJML and Beefree templates carry no program logic, so nothing is lost by going through the design. The same functions could later power editor imports.

MJML (mjml pinned at 5.4.1)

• mj-attributes, mj-class and mj-include are resolved. An include it can't read (outside the folder given) fails the template, naming it: its check can't see what's missing.
• These become editable blocks: sections, columns, text, buttons, images, dividers, spacers, social (as Social blocks), navbar and simple tables.
• Hero overlays, carousels and accordions stay as MJML's own HTML. They're counted separately as not editable, so they don't inflate ✓.
• MJML 3 files fail with a pointer to mjml-migrate.
• Checked against MJML's own output.

Beefree

• Classic JSON in its known wrappers and versions. An unknown version fails loudly.
• Rows, columns and modules map to blocks.
• Checked against Beefree's HTML export when <name>.html sits beside the JSON. Otherwise the template is reported as unverified, and --strict fails it.

Declared differences (convert-core)

A converter can declare specific changes it knows it makes. The editor's Social block writes alt text as "Facebook icon", and Beefree's phone hamburger menu has no equivalent. The check expects these and lists them under "looks different" instead of flagging a converter bug. Anything undeclared still fails, and --strict still fails declared ones.

Results on real templates

MJML (114 documents)	112 ✓, 0 ✗, 96.2% of blocks editable. The other 2 don't compile in MJML either.
Beefree (107 templates)	107 converted, exact design round trip, 97.6% editable. 33 ✓ / 0 ✗ against Beefree's exports; 74 have no export.

Committed fixtures are permissively licensed (MIT, Apache-2.0), with LICENSE and NOTICE files. The rest of the corpus was used locally only.

Validation

• migrate 361 tests and convert-core 219 pass; typecheck is clean.
• New coverage: per-tag and per-module unit tests, fixture tests, CLI e2e for both sources, and declared-difference tests (an undeclared alt change still fails).

Release

@unlayer/migrate publishes as 0.2.0 (committed: new sources are a minor), with the Elements range ^0.3.0 set in #69.