Replaces the M0 stub bodies in `crates/mxaccess/examples/` with real
consumer-facing demos against the M4 NMX `Session` surface. Each example
gates on `MX_LIVE` and prints a friendly bypass message when the live
env vars aren't populated, so `cargo build --workspace --all-targets`
stays green in CI without an AVEVA install.
Five examples target the proven NMX path (build + connect + demo +
shutdown):
- `connect-write-read` — `Session::write_value` + `read` round-trip; the
30-line consumer-experience target from `design/60-roadmap.md` M4 DoD.
- `subscribe` — single-tag `Subscription` stream; drains 5 updates or
10s timeout, then `unsubscribe` cleanly.
- `recovery` — `RecoveryPolicy { max_attempts: 3, delay: 250ms }`
+ spawned `recovery_events()` listener consuming the broadcast.
- `multi-tag` — per-tag `subscribe` loop merged via
`futures_util::stream::select_all`; matches the .NET cs:250-270 shape
(no atomic subscribe-many RPC on the wire).
- `secured-write` — `write_value_secured_at` exercising both single-user
(`current_user_id == verifier_user_id`) and two-person paths per
`wwtools/mxaccesscli/src/MxAccess.Cli/Commands/WriteCommand.cs:151-155,196-199`.
Two examples hold the place for downstream milestones:
- `subscribe-buffered` — pattern-matches on `Error::Unsupported` from
`Session::subscribe_buffered` (M6) and exits 0 with an explanation.
- `asb-subscribe` — same shape against `Session::connect` (M5 ASB).
All five live examples share an inline `LiveEnv::from_process` helper,
a dashed-hex `parse_guid`, and a `StaticResolver` that returns canned
metadata for the configured `MX_TEST_TAG`. The duplication is
intentional — Cargo examples are meant to be self-contained and read
top-to-bottom; consumers swap `StaticResolver` for a tiberius-backed
Galaxy resolver (followup F14) without touching any other example.
Test count delta: 524 → 524 (+0; examples are demos, not tests)
Open followups touched: F17 logged (Guid::parse_str helper to dedupe
the per-example dashed-hex parser).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
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