Adds `Guid::parse_str(&str) -> Result<Guid, RpcError>` to
`crates/mxaccess-rpc/src/guid.rs` as the inverse of the existing
`Display` impl. Accepts the canonical dashed-hex form, optionally
braced (.NET `B` format), case-insensitive, and tolerant of bare
32-char hex without dashes. Single-pass char-by-char nibble accumulator
avoids per-byte string allocation; applies the same byte-swap of
groups 1-3 that the `Display` impl reads.
Eight new tests cover round-trip against the existing `Display`
fixture (`crates/mxaccess-rpc/src/guid.rs:111-119`,
`b49f92f7-c748-4169-8eca-a0670b012746`), braces, uppercase, no-dashes,
zero-GUID, too-short, too-long, and non-hex rejection.
The five live-NMX examples (`connect-write-read`, `subscribe`,
`recovery`, `multi-tag`, `secured-write`) lose their per-file 15-line
`parse_guid` helpers in favour of the canonical implementation.
`asb-subscribe` and `subscribe-buffered` are unaffected — they don't
parse GUIDs.
Test count delta: 524 → 532 (+8)
Open followups touched: F17 resolved.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
48d3a9d6da