eas deploy (Hosting): "The multipart part asset name is unexpected" on large static site (~48k files) #4257

Summary

eas deploy --prod (EAS Hosting) consistently fails during the asset-upload step, immediately after ✔ Created deployment, with:

The multipart part asset name is unexpected
    Error: deploy command failed.

This is for a large static Expo Router web export (npx expo export --platform web): roughly 47,000+ HTML pages, ~49,000 total files, ~1.1–1.25 GB.

Reproduction / environment

• eas-cli 22.2.0 (also reproduced on latest via npm install -g eas-cli).
• Static web export deployed with eas deploy --prod --non-interactive.

What we've verified

• Deterministic, not a network issue: fails identically from a local machine and from a GitHub Actions runner (stable network), every time, after a full upload (~30–40 min).
• Inspected the deployment manifest via eas deploy --dry-run (the assets.json inside deploy.tar.gz). It lists ~61k assets and is clean: no non-ASCII names, no quotes/control chars, no empty names, no duplicate hashes, no case-insensitive collisions, and no file/directory name clashes.
• Reduced file count from ~61k to ~49k (inlined per-page SVGs). Still fails with the same error.

Questions

1. What are the actual limits for an EAS Hosting deployment — max number of files/assets and max total upload size?
2. Is The multipart part asset name is unexpected a known issue with the asset-batch upload for deployments with tens of thousands of files (a batch count/size ceiling)?
3. What's the recommended approach for deploying a large static site (47k+ pages) on EAS Hosting — a higher plan, a config change (.easignore, chunking), or is a site this size outside EAS Hosting's intended scale?

Happy to share the project ID privately with a maintainer. Thanks!