v0.4.1 — The first chain reorganization, survived (2026-08-21)

The height-264 anchor published in v0.4.0 was orphaned. It carried valid
difficulty-1 work and the public seed advertised it as its tip, but the laboratory's
miner produced a competing block at the same height and extended it — two blocks beat
one, and our block left the active chain. This is the anchor chain's first
reorganization, and the direct consequence of it having had two independent miners
since 2026-08-19.

orphaned   0000000032580c2f…  height 264   valid PoW, briefly the tip, now an orphan
re-anchor  000000001a5380c4c618b2fd2dc4a8768e5cd807cf3122a24ce2fc4c548dc112
           height 269, nNonce 796895470
window     B0 263  ≺  acquisition  ≺  C 269      (six blocks, not adjacent)
verdict    SANDWICH_PASS — all checks true, buried 3 deep
bundle     vectors/valid/roughtime-sandwich-bundle.cbor
           sha256 bf22c1586a2dff27…

Nothing in the evidence depended on which block won. The acquisition, every
Ed25519 and post-quantum signature, and the epoch-3 checkpoint are byte-identical to
what v0.4.0 published; only the anchor's identity changed. Re-anchoring meant mining
the same checkpoint payload onto the new tip, which widened the causal window and
left both bounds intact — and the verifier proves it rather than asserting it:
S_LINKAGE_B0_TO_C now walks the five intervening blocks (the winning 264 and its
265–268) to establish the unbroken path from B0 to the new anchor.

This is the construction's first encounter with a chain reorganization, and it
behaved as designed: a wider window, no lost evidence, every claim re-verified. The
orphaned block's bytes are preserved in live/anchor-evidence/orphans/ and the v0.4.0
release note above is left standing with a pointer to the correction — a claim that
quietly disappears teaches a reader nothing.

The laboratory's own record of the event, written from the chain bytes rather than from
this project's perspective, is in the original-bitcoin-laboratory genesis repository
under bitcoin-findings/2026-08-21-first-reorganization/.