History of Web Packaging

Roughly:

1. 2014: W3C TAG designs a format similar to multipart/* MIME to make it possible to bundle several resources together: https://www.w3.org/TR/2015/WD-web-packaging-20150115/
2. Late 2016: Chrome's emerging-markets team proposes to expand the spec to work for peer-to-peer sharing and content distribution, by adding an index, sub-packages, and signatures: https://github.com/WICG/webpackage/blob/@{2016-11-02}/README.md
3. 2017-03: jyasskin moves the package structure from multipart/* to a binary format: https://github.com/WICG/webpackage/blob/@{2017-03-30}/README.md. Authors sign a list of hashes of package resources plus version constraints on sub-packages.
4. 2017-07: Packages presented to IETF99, with https://tools.ietf.org/html/draft-yasskin-dispatch-web-packaging-00.
5. 2017-08: A use cases document is published, and the design is split into signed single responses and "bundles". This loses the ability to require that different resources have compatible versions.
6. 2018-01: Safari expresses concern, and Mozilla expresses opposition to the plans.
7. 2018 March-October: W3C TAG review
8. 2019-03: Chrome ships the "b3" version of signed exchanges.