Joseph Doherty
f98ab9846d
R3's verdict gains an aside documenting why the original native MxAccess `OnWriteComplete` event has historically only fired for the one exact 5-byte pattern `00 00 50 80 00` (= `MxStatus.WriteCompleteOk`). Verified at: - `src/MxNativeClient/MxNativeCompatibilityServer.cs:756` — `if (!evt.Message.IsMxAccessWriteComplete) return;` gates the consumer-facing `WriteCompleted` event. - `src/MxNativeCodec/NmxOperationStatusMessage.cs:18` — `IsMxAccessWriteComplete` requires `Format == StatusWord && StatusCode == 0x8050 && CompletionCode == 0x00`. Every other completion frame is silently dropped — the 1-byte `0x00`/`0x41`/`0xEF` ones, plus any non-success status word. This was the underlying reason R3/R4 looked unsolvable for a year: the answer "we don't know how to map" was actually "the native compatibility shim deliberately doesn't map these because firing typed failure events on ambiguous bytes was never a goal." Path A's `MxStatus::from_packed_u32` (commit `c73a33e`) closes the asymmetry on the Rust side: `Session::operation_status_events()` exposes ALL typed outcomes the upstream synthesizer produces, not just the WriteCompleteOk slice. The Rust port now has strictly broader operation-status visibility than the .NET reference offered. Recorded so future contributors don't re-derive this from scratch. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
design/ — Rust port architectural plan
This folder is the design contract for the Rust replacement of AVEVA/Wonderware MXAccess. It is the gap between the .NET reference in src/ and the Rust crates that will be written under a sibling rust/ workspace (per CLAUDE.md).
The folder is structured as a small set of focused documents. Read in order; each builds on the previous.
| File | Purpose |
|---|---|
00-overview.md |
Mission, two-layer goal, architectural principles, non-goals |
10-raw-layer.md |
Byte-accurate raw MXAccess layer (codec + transport + session) |
20-async-layer.md |
Idiomatic Tokio async layer on top of the raw layer |
30-crate-topology.md |
Cargo workspace, crates, dependencies, build/test commands |
40-protocol-invariants.md |
Bill of materials: IIDs, opnums, envelope/handle bytes |
50-error-model.md |
MxStatus, error types, panic/cancellation policy |
60-roadmap.md |
Milestones M0..M6, validation strategy |
70-risks-and-open-questions.md |
Parity gaps, unproven flows, cross-platform constraints |
dependencies.md |
Cross- and within-milestone parallelism map; agent budget per phase |
review.md |
Adversarial review log (BLOCKER/MAJOR/MINOR/NIT findings, all resolved) |
prompt.md |
/loop driver prompt for autonomous M2–M6 execution |
followups.md |
Open / resolved deferred work items; auto-triaged by prompt.md Step 0 (created on first /loop run if missing) |
The design is grounded in the .NET reference at src/ and the protocol artifacts in docs/, analysis/, and captures/. Do not introduce protocol behavior in these documents that is not already proven in the reference. When adding a new claim about wire format, cite either:
- a
.csfile path insrc/MxNativeCodec/,src/MxNativeClient/, orsrc/MxAsbClient/, or - a
docs/*.mdspec file, or - a
captures/0NN-frida-*directory oranalysis/frida/*.tsvrow.
This folder is documentation, not code. When the Rust workspace is created, the design here is the contract it must satisfy. When evidence in captures/ invalidates a design decision here, update the design first, then the code.
Reading order
- New contributor: 00 → 30 → 10 → 40 → 20 → 50 → 60 → 70.
- Protocol question: 40 first, then the relevant section of 10.
- API question: 20 first, then 50.
- Planning a milestone: 60 first, cross-reference 70 for blockers.
- Scheduling concurrent work:
dependencies.mdfor the per-phase parallelism map. - Driving M2–M6 autonomously via
/loop:prompt.md(and thefollowups.mdtriage log it maintains).