Key points: - UASF participants ran validating full nodes (…

Key points:
- UASF participants ran validating full nodes (BIP148). They explicitly enforced “reject non‑SegWit‑signaling blocks after Aug 1, 2017.” That is validation, not SPV.
- Their credible commitment shifted incentives: to avoid a split and orphan risk, miners adopted BIP91 (a miner-activated soft fork) so SegWit would lock in smoothly.
- SegWit was a soft fork (tightening rules). Activation required miners to mine SegWit-valid blocks and economic nodes to accept them. No one had an “upgrade key;” it was coordination across miners and economic validators.
- Non‑validating nodes (SPV clients) weren’t the driver.