Files
mxaccess/design
Joseph Doherty ad1cf2351c [F36 + F40 + F44] M6 wave 1: subscribe_buffered (NMX) + metrics + evidence
Three M6 sub-followups landed in this wave (sub-agent worktrees +
manual reconciliation in main):

**F36 — Session::subscribe_buffered (NMX) per R2 single-sample**
- `BufferedOptions::rounded_update_interval_ms()` — 100ms rounding
  helper mirroring MxNativeCompatibilityServer.cs:638
  ((updateInterval + 99) / 100) * 100, saturating on overflow.
- `Session::subscribe_buffered` (public, lib.rs:604) delegates to
  the new private `subscribe_buffered_nmx` which uses the buffered
  RegisterReference path: item_definition suffixed with
  `.property(buffer)`, subscribe=true (no separate
  AdviseSupervisory follow-up — verified against capture 082).
- Per R2 verified at wwtools/mxaccesscli/docs/api-notes.md the wire
  semantic is single-sample-per-event with a server-side cadence
  knob; rounded_ms is held client-side only (native MXAccess does
  not emit a separate SetBufferedUpdateInterval RPC, verified by
  absence in 079/082 captures).
- New crates/mxaccess/examples/subscribe-buffered.rs.
- New crates/mxaccess-codec/tests/buffered_register_reference_parity.rs:
  4 tests (capture 079/082 round-trip, suffix helper, constructive
  forward-build vs capture 082).

**F40 — Optional metrics feature**
- New crates/mxaccess/src/metrics.rs (275 lines): `pub(crate)`
  thin wrappers (`record_write_latency`, `record_read_latency`,
  `inc_writes`, `inc_reads`, `inc_advises`, `inc_recovery_*`,
  `set_active_subscriptions`, etc.) that compile to no-ops under
  `#[cfg(not(feature = "metrics"))]`. Call sites in session.rs +
  asb_session.rs invoke them unconditionally; the gate is inside
  the wrapper.
- `metrics = { version = "0.24", optional = true }` added to
  workspace + mxaccess crate Cargo.toml.
- Default build: zero metrics dep, zero runtime cost.

**F44 — Buffered batch + suspend capture decode evidence**
- New docs/M6-buffered-evidence.md: per-capture summary for
  077, 079, 080, 081, 082, 094 — call sequence, key wire bytes,
  R2/R5 verdict.
- R2 confirmed silently as "not a real risk" — single-sample
  observed across 079/080/082/094.
- R5 trigger conditions documented from capture 077: AdviseSupervisory
  + Suspend pair, 1-second intervals, succeeds on enum attributes.
- design/70-risks-and-open-questions.md R2/R5 status updated.

Workspace: 759 → 792 tests, clippy clean, rustdoc -D warnings clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-06 05:12:17 -04:00
..

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 M2M6 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 .cs file path in src/MxNativeCodec/, src/MxNativeClient/, or src/MxAsbClient/, or
  • a docs/*.md spec file, or
  • a captures/0NN-frida-* directory or analysis/frida/*.tsv row.

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.md for the per-phase parallelism map.
  • Driving M2M6 autonomously via /loop: prompt.md (and the followups.md triage log it maintains).