v0.4.2 — why no other chain, and the backlog written down

Still public beta. No security review, no Czech eIDAS counsel review. The timestamps are real
and independently verifiable; treat the app itself as unfinished.

Live at https://elkojo.github.io/xNotary/

Documentation only — the app is byte-for-byte the same product as v0.4.1. This release exists
so that the running build points at the source that describes it: every deployed build links the
exact commit it came from, which is what AGPL § 13 asks of anyone running this as a service, and
that link had fallen behind the documentation.

Why Bitcoin, and no other chain

Letting the user pick a chain was investigated and dropped. The README now records the findings,
re-measured rather than recalled, because the question recurs.

• Litecoin. Both public OpenTimestamps calendars have no DNS record at all, so there is
  nothing to stamp against without running one — a server and a funded wallet, which ends the "no
  backend" guarantee. And the reference client's
  LitecoinBlockHeaderAttestation.verify_against_blockheader() raises NotImplementedError, so
  ots verify — the command printed on every Certificate 1 — fails on such a proof. Litecoin's
  security is not the objection; nothing being able to check the proof is.
• Bitcoin SV. OpenTimestamps has no BSV attestation type, so it would need a private tag no
  other client can read — a certificate only xNotary could verify, which is the one thing this
  project must never produce. It also runs at roughly 0.023% of Bitcoin's hashrate on the same
  SHA-256 algorithm, with a documented 14-block reorganisation in 2021. A timestamp is worth
  what it costs to rewrite the block holding it.

The stronger move, if redundancy is the goal

Not a second blockchain — a second kind of authority: a qualified RFC 3161 timestamp from a
trust service provider, alongside the Bitcoin anchor. Bitcoin gives independence from every
institution; a qualified timestamp gives standing with the institutions that matter in law. They
fail in unrelated ways, which is what redundancy is supposed to mean. Two chains fail the same way
and differ only in price.

It is the first item on the roadmap for that reason.

The backlog is now written down

The post-MVP plan was a single paragraph. It is now a prioritised roadmap that says what each item
needs and what blocks it — including that in-browser validation against the EU Trusted Lists is
blocked because the EU's own list server sends no CORS header, and that under eIDAS Art 33 only a
qualified provider may ever give a qualified validation, whatever xNotary implements.

Also recorded: the smaller engineering items, and one honest caveat — a paid archive would make
the "nothing is retained" principle false on the day it ships unless it is reworded first.