[M2/M4] mxaccess-rpc: Guid::parse_str + dedupe examples (resolves F17)

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>

design/followups.md

@@ -60,12 +60,6 @@ move to `## Resolved` with a date + commit hash.
 **Why deferred:** Wave-2 `Session::recover_connection` validates the policy and emits `RecoveryEvent::Started` + `RecoveryEvent::Recovered` on each call but does **NOT** actually tear down + re-establish the NMX transport / re-advise active subscriptions. The .NET reference's `RecoverConnectionCore` (`MxNativeSession.cs:442-474`) does all three: builds a replacement `ManagedNmxService2Client` via `CreateRegisteredService`, re-`Connect`s every `_publisherEndpoints` entry, re-`AdviseSupervisory`s every entry in `_subscriptions`, then atomically swaps the old service for the new one. Porting this to Rust requires (a) tracking the active subscriptions inside `SessionInner` (currently they're owned by the consumer's `Subscription` handles, with no central registry); (b) the long-lived connection task per R15 in `design/70-risks-and-open-questions.md` so swap-in-place is safe under concurrent operations; (c) a way to re-create the `CallbackExporter` (or keep the existing one bound while the underlying transport is replaced — needs design work).
 **Resolves when:** R15's long-lived connection task lands and `SessionInner` gains a subscription registry. At that point the recover loop becomes ~50 lines: for `attempt in 1..=max_attempts`, emit Started → drop+rebuild NmxClient → `register_engine_2` with the existing OBJREF → re-advise every registered correlation_id → emit Recovered (or Failed + sleep delay + continue, mirroring the `cs:407-440` shape exactly).
 
-### F17 — `Guid::parse_str` helper (dashed-hex string parser)
-**Severity:** P3
-**Source:** M4 wave 3, `crates/mxaccess/examples/*.rs`
-**Why deferred:** Each of the five live-NMX examples (`connect-write-read`, `subscribe`, `recovery`, `multi-tag`, `secured-write`) duplicates a 15-line `parse_guid` helper that takes a `12345678-1234-1234-1234-123456789012` style string and produces the wire-byte `Guid([u8; 16])`. The helper belongs on `mxaccess_rpc::guid::Guid` itself (paired with its existing `Display` impl) so consumer code that wires up `MX_NMX_SERVICE_IPID` doesn't reimplement the LE-leading byte-swap convention. Deferred to keep this iteration's diff focused on examples; the parse path has no corresponding .NET reference helper to mirror so it's a Rust-side ergonomic addition rather than a parity port.
-**Resolves when:** Add `pub fn parse_str(s: &str) -> Result<Guid, RpcError>` on `mxaccess_rpc::guid::Guid` with a round-trip test against the existing `Display` fixture (`crates/mxaccess-rpc/src/guid.rs:111-119`). Update the five examples to call it. Single-iteration follow-up.
-
 ### F14 — `tiberius`-backed SQL implementation of `Resolver` + `UserResolver`
 **Severity:** P2
 **Source:** M3 stream A, `crates/mxaccess-galaxy/src/sql.rs` (constants present, no client wiring yet)
@@ -94,3 +88,6 @@ move to `## Resolved` with a date + commit hash.
 
 ### F9 — `ObjectExporterClient.cs` ResolveOxid wrapper methods
 **Resolved:** 2026-05-05. Both portable methods land in `crates/mxaccess-rpc/src/object_exporter_client.rs`: `resolve_oxid_unauthenticated` (mirrors `cs:14-30`) and `resolve_oxid_with_managed_ntlm_packet_integrity` (mirrors `cs:66-81`). Each opens a TCP connection, binds to `IObjectExporter`, calls opnum 0 with the encoded request, and decodes the response — preferring `parse_resolve_oxid_result` then falling back to `parse_resolve_oxid_failure` for short stubs. The two SSPI flavours (`ResolveOxidWithNtlmConnect`, `ResolveOxidWithNtlmPacketIntegrity`) wrap .NET's `System.Net.Security.SspiClientContext` and are explicitly out of scope for the Rust port — that's a permanent skip, not a deferral.
+
+### F17 — `Guid::parse_str` helper (dashed-hex string parser)
+**Resolved:** 2026-05-05. `Guid::parse_str(&str) -> Result<Guid, RpcError>` landed in `crates/mxaccess-rpc/src/guid.rs:65-112` as the inverse of the existing `Display` impl. Accepts the canonical dashed-hex form, optionally wrapped in `{}` braces (.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; the same byte-swap of groups 1-3 the Display impl does is applied after the raw hex pass. Eight new tests cover round-trip against the `Display` fixture (`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`) lost their per-file 15-line `parse_guid` helpers in favour of the canonical implementation. Test count delta: 524 → 532 (+8).