There are no standards and protocols in place for this, and there's no browser that enforces this.
If you think that taking something that's 80% there and filling in the last 20% for yourself counts as something that's "already" possible, then nothing is new and everything is already possible.
> Hashes of leaf resources would be embedded in parent resources up to the root document that you could announce out-of-band (e.g. https://example.com on 23rd of November 2017 has hash 1234566...)
This is really janky and not at all what I'm talking about. What I'm talking about is as simple as what happens now, e.g., "GitLab/Mastodon/Whatever XX.x Released".
If you think that taking something that's 80% there and filling in the last 20% for yourself counts as something that's "already" possible, then nothing is new and everything is already possible.
> Hashes of leaf resources would be embedded in parent resources up to the root document that you could announce out-of-band (e.g. https://example.com on 23rd of November 2017 has hash 1234566...)
This is really janky and not at all what I'm talking about. What I'm talking about is as simple as what happens now, e.g., "GitLab/Mastodon/Whatever XX.x Released".