feat(ab): native managed transport is the default for AbCip and AbLegacy; libplctag remains as fallback

Task 22 (spec section 8 P5), with the controller rulings that exclude PLC-5 and LogixPccc.

- Transport is nullable on both option records; null (key absent) means "use the default" and is
  never serialized. Factory DTO parse: absent -> null; a bad value still fails via ParseEnum.
- One resolver per driver (AbCipTransportResolver / AbLegacyTransportResolver), used by the driver
  constructor, the Test Connect probe and (through the driver) the CLI.
  AbCip: null -> Native. AbLegacy: null -> Native unless any device is Plc5 or LogixPccc, then the
  whole driver resolves to Libplctag. Explicit values always win; explicit Native with a
  Plc5/LogixPccc device logs one Warning at init.
- Init log shows configured vs effective, e.g. transport=Native (default).
- AdminUI forms: "Default (...)" / "Native (managed)" / "libplctag (fallback)". Default omits the
  key on save (reverses Task 19's explicit re-emit, which would have pinned every edited driver).
- CLIs: --transport default|native|libplctag, default "default" via the resolver, so
  --plc-type Plc5 with no --transport runs libplctag.
- Tests pinned to Libplctag where a default-path runtime was created: found by instrumenting the
  native factories with the current xUnit test name (one unit test, AbLegacyReinitConfigAdoption;
  plus the two fixture-gated AbCip probe E2E tests whose exact messages were proven on libplctag).
  TransportMatrix and the differential harness already pass explicit transports.
- Switch/resolver/CLI/form tests are falsified by mutating the resolver (default -> Libplctag,
  exclusion removed, AbLegacy default -> Libplctag): each mutation turns them red.
- Replaces the inline role-name literal in AbCipDriverFactoryExtensions' ParseEnum call with a named
  constant; RoleAuthorityGuardTests was already red on the base commit for that line.
- Docs: AbCip.md / AbLegacy.md default + release note; CLAUDE.md AB section.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

docs/drivers/AbCip.md

@@ -76,7 +76,7 @@ the driver's `DriverConfig` JSON. Key fields:
 - **`Devices`** — one `AbCipDeviceOptions` per PLC (`HostAddress`, `PlcFamily`, optional `DeviceName`, per-device `AllowPacking` / `ConnectionSize` overrides).
 - **`Tags`** — pre-declared `AbCipTagDefinition` list; `Members` for UDT fan-out, `SafetyTag` for GuardLogix safety-partition tags.
 - **`Probe`** — connectivity-probe `Enabled` / `Interval` / `Timeout` / `ProbeTagPath`.
-- **`Transport`** — `Libplctag` (default) or `Native`; see [Transport](#transport-transport-option).
+- **`Transport`** — absent (default ⇒ `Native`), `Native`, or `Libplctag` (fallback); see [Transport](#transport-transport-option).
 - **Discovery** — `EnableControllerBrowse` (`@tags` walk) and `EnableDeclarationOnlyUdtGrouping` (whole-UDT read fast path).
 - **Alarms** — `EnableAlarmProjection` + `AlarmPollInterval` for the ALMD projection.
 
@@ -89,24 +89,46 @@ The driver has two interchangeable wire transports, selected by one `DriverConfi
 
 | Key | Values | Default | Serialization |
 |---|---|---|---|
-| `transport` | `Libplctag` \| `Native` | `Libplctag` | string, case-insensitive on read, written as `"Libplctag"` / `"Native"` |
+| `transport` | absent \| `Native` \| `Libplctag` | absent ⇒ `Native` | string, case-insensitive on read, written as `"Libplctag"` / `"Native"`; "use the default" is encoded by OMITTING the key |
 
-- **`Libplctag`** (default) drives the libplctag native library, as before.
-- **`Native`** is a managed in-process EtherNet/IP + CIP client (`Driver.Ab.Transport`). It is **opt-in**:
-  the default stays `Libplctag` until the real-press read-only gate has run and the default is flipped.
+- **`Native`** (the default since Task 22) is a managed in-process EtherNet/IP + CIP client
+  (`Driver.Ab.Transport`).
+- **`Libplctag`** (fallback) drives the libplctag native library, as before.
+- An absent key means "use the default". It is resolved in one place, `AbCipTransportResolver`, which the
+  driver, the Test Connect probe and the CLI all go through. An explicit value always wins.
 - A bad value fails like a bad `PlcFamily`; the Test Connect probe reports "Config JSON is invalid".
 - A change takes effect when the driver instance is **recreated**. A deploy that changes `DriverConfig`
   does this (`DriverHostActor` respawns the child, #516). `ReinitializeAsync` alone keeps the transport
   it was constructed with.
-- AdminUI: the **Transport** dropdown in the advanced section of the AbCip driver form ("libplctag
-  (default)" / "Native (managed)"). Saving another field preserves it.
-- The driver logs `transport=<X>` at Information on every init, including reconnect re-inits. AbCip
+- AdminUI: the **Transport** dropdown in the advanced section of the AbCip driver form ("Default (Native)" /
+  "Native (managed)" / "libplctag (fallback)"). **Default omits the key on save**, so a defaulted driver stays
+  defaulted; saving another field preserves an explicit value and preserves absence.
+- The driver logs `transport=<effective> (default|configured)` at Information on every init, e.g.
+  `transport=Native (default)`, including reconnect re-inits. AbCip
   drivers now receive the host logger (they previously ran on a null logger, so none of their warnings
   reached the node log); expect previously invisible warnings, e.g. a probe enabled with no probe tag path.
-- CLI: `--transport native|libplctag` (default `libplctag`).
+- CLI: `--transport default|native|libplctag` (default `default`, which goes through the same resolver).
 - libplctag is confined to `Libplctag*.cs` adapters, enforced by a source-scan guard
   (`LibplctagConfinementGuardTests`), so removing it later is mechanical.
 
+### Release note — native is the default (Task 22)
+
+- **The native managed transport is now the default.** A driver config with no `transport` key runs
+  `Native`; libplctag remains available as the fallback.
+- ⚠️ **Client-visible:** native reports **`BadTypeMismatch`** for a mis-authored same-width type (for example a
+  tag authored `DINT` where the controller holds a `REAL`), where libplctag returned Good garbage. Correct the
+  authored type; see [Native transport behaviour](#native-transport-behaviour).
+- **To fall back**, set `"transport": "Libplctag"` in the driver config (or pick "libplctag (fallback)" in
+  the AdminUI dropdown).
+- **When it takes effect:** a change of transport — including this default flip for an existing driver with
+  no key — takes effect when a deploy recreates the driver instance, not on `ReinitializeAsync`.
+- **Evidence, and its limits:** AbCip **reads** (plus browse and templates) were proven on a production
+  CompactLogix 5069-L320ERS2 (**Z-35162**, read-only, 2026-10-08; see
+  [gate results](../plans/2026-10-07-native-ab-transport-gate-results.md) §Real press). AbCip **writes** are
+  simulator-proven only (`ab_server`), as is all of AbLegacy.
+- AbLegacy has its own exclusion: a defaulted AbLegacy driver with any PLC-5 or `logixpccc` device stays on
+  libplctag (see [AbLegacy.md §Transport](AbLegacy.md#transport-transport-option)).
+
 ## Native transport behaviour
 
 - **One CIP connection and one request scheduler per device** (`DeviceSessionPool`), shared by reads,
@@ -137,15 +159,15 @@ The driver has two interchangeable wire transports, selected by one `DriverConfi
 ## Known gaps
 
 - ⚠️ **Native writes are verified against `ab_server` only (simulator-only), never a real controller.** The
-  real-press gate (Task 21) is **read-only** and **has not run yet**; this page makes no real-controller
-  claim for the native transport. Results land in
+  real-press gate (Task 21) was **read-only**: it proved native reads, browse and templates on Z-35162
+  (2026-10-08) and nothing else. Results:
   [native-ab-transport-gate-results](../plans/2026-10-07-native-ab-transport-gate-results.md).
 - **libplctag cannot be deleted** until a bench controller allows write verification.
 - Wide-struct fragmented writes (8-byte alignment) are unit-tested only, never proven on a controller (#567).
 - Native browse: listing pages are unpaced, and template reads outside an enumeration open a connection per
   call (#572).
 - Micro800, routed and `logixpccc` paths are covered by `ab_server` only. The Micro800 profile passes
-  natively; the planned default flip excludes `logixpccc`.
+  natively. The AbLegacy default excludes `logixpccc` (and PLC-5).
 - Follow-up issues for this workstream: #564 to #577.
 - Fixed along the way (pre-existing on master): `ab://host:44818/` with an empty CIP path (Micro800,
   unrouted MicroLogix) failed on libplctag with `ErrorBadData` because the adapter sent `Path=""`; it now