Pre-computed record keys for my blog posts

For every one of my blog posts, my static site generator1 pre-computes an atproto TID defined by the post date time and its slug: const TID_ALPHA: &[u8; 32] = b"234567abcdefghijklmnopqrstuvwxyz"; fn atproto_tid(date_rfc3339: &str, slug: &str) -> Result<String, minijinja::Error> { let dt = OffsetDateTime::parse(date_rfc3339, &Rfc3339).map_err(|err| { minijinja::Error::new( ErrorKind::InvalidOperation, format!( "atproto_tid(): first argument must be an RFC3339 date (e.g. post.date_iso); got '{date_rfc3339}': {err}" ), ) })?; let micros = (dt.unix_timestamp_nanos() / 1_000) as u64 & 0x1F_FFFF_FFFF_FFFF; let digest = blake3::hash(slug.as_bytes()); let clock = u16::from_be_bytes([digest.as_bytes()[0], digest.as_bytes()[1]]) as u64 & 0x3FF; let mut v = ((micros << 10) | clock) & 0x7FFF_FFFF_FFFF_FFFF; let mut out = [0u8; 13]; for slot in out.iter_mut().rev() { *slot = TID_ALPHA[(v & 0x1F) as usize]; v >>= 5; } // Every byte comes from TID_ALPHA (ASCII), so no UTF-8 validation needed.…