Split figma-transformer to Packagist so consumers stop vendoring the monorepo

[chubes4]

Problem

php-transformer was split to Packagist in #802 with .github/workflows/php-transformer-split.yml and a .gitattributes that keeps the dist lean. figma-transformer never got the same treatment. It has a package-root composer.json (psr-4 → src/) but no .gitattributes and no split mirror, so there is no published package to install.

Consumers therefore vendor the entire monorepo. static-site-importer/composer.json declares an inline type: package entry pointing at https://github.com/Automattic/blocks-engine/archive/refs/tags/figma-transformer-v0.1.3.zip with psr-4 rooted at figma-transformer/src/.

Measured cost in a shipped product

The published static-site-importer v1.8.1 release asset is 8,191,363 bytes (6.77MB of compressed entries, 28.36MB expanded, 3,080 files). Breaking the archive down by compressed size:

vendor/automattic/blocks-engine-figma-transformer   5077.3KB  2091 files   75.0% of vendor payload
vendor/automattic/blocks-engine-php-transformer      760.1KB   261 files
vendor/league/commonmark                             241.4KB   382 files

Inside the figma vendor directory:

fixtures/            3095.5KB  1067 files   <- Figma test fixtures
php-transformer/      764.6KB   448 files   <- complete duplicate copy, including its tests
packages/             456.8KB   392 files   <- the JS engine
figma-transformer/    704.8KB   154 files   <- the only part anyone installs it for
docs/ scripts/ tests/ CONTEXT.md CONTRIBUTING.md ~54KB

~4.37MB of the 6.77MB compressed package — 63% — is Figma fixtures, a duplicate php-transformer tree, and a JavaScript engine. The duplicate php-transformer copy is 448 files against the real package's 261, because it predates the #802 export-ignore and still carries tests/.

What the consumer actually needs from all of it is one class. The only FigmaTransformer\* reference in SSI's runtime PHP is Compression\ZstdCommandDecoder, in includes/class-static-site-importer-figma-import.php.

Scope

• Add figma-transformer/.gitattributes mirroring the php-transformer one: export-ignore tests/, dev tooling, homeboy.json, composer.lock.
• Extend the Publish php-transformer to Packagist via automated subtree-split mirror #802 subtree-split mirror to figma-transformer, publishing automattic/blocks-engine-figma-transformer from a split repo so the package root is figma-transformer/ rather than the monorepo root.
• Let consumers drop the inline repositories entry and require the real package.

Acceptance

• The installed vendor directory contains figma PHP source plus docs/contracts only — no fixtures/, no packages/, no nested php-transformer/.
• git archive of the split prefix carries no test or fixture trees.
• The figma import path still resolves Compression\ZstdCommandDecoder and the fig fixture e2e passes.
• Downstream, the static-site-importer release asset drops below 3MB.

Note for the consumer migration

static-site-importer.php already probes both layouts when bootstrapping — vendor/automattic/blocks-engine-figma-transformer/figma-transformer/figma-transformer.php and .../blocks-engine-figma-transformer/figma-transformer.php. The split package shape is already anticipated by the loader, so the consumer side should be close to a dependency swap.

Downstream tracker: Automattic/static-site-importer#1397. Sibling packaging cleanup for php-transformer: #1359.

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AI assistance disclosure: this issue was investigated and drafted by Claude Sonnet 4.6 running in Claude Code, operated by @chubes4. The AI inspected blocks-engine at trunk (f8e12d04), static-site-importer at main (52d589f), and the published v1.8.1 release asset, and computed the archive breakdowns quoted above by reading the ZIP central directory. Reviewed by a human before posting.