# Compatibility Validation

## Purpose

This document records how the standalone LinuxCNC WASM port currently proves
that migrated behavior remains tied to LinuxCNC source code and fixture
semantics.

The primary native validation command is:

```bash
wasm-port/tests/native/verify_native_probes.sh
```

The current WASM smoke validation command is:

```bash
wasm-port/tests/wasm/node/verify_ini_wasm.sh
```

The current WASM interpreter-core smoke validation command is:

```bash
wasm-port/tests/wasm/node/verify_interp_wasm.sh
```

The current OPFS host-boundary validation command is:

```bash
wasm-port/tests/opfs/node/verify_file_service.sh
```

The current browser smoke validation command is:

```bash
wasm-port/tests/browser/verify_ini_panel_browser.sh
```

The current browser interpreter smoke validation command is:

```bash
wasm-port/tests/browser/verify_interp_browser.sh
```

The current aggregate host/WASM/browser smoke command is:

```bash
wasm-port/tests/host/verify_host_smokes.sh
```

## Validation Chain

The native validation script runs these checks in order:

1. `tools/verify_upstream_baseline.sh`
   Confirms `../linuxcnc` is at the recorded upstream commit in
   `tools/upstream-baseline.txt`.
2. `tools/verify_vendor_sync.sh`
   Confirms every manifest file is present in `vendor/linuxcnc/`, no extra
   vendored file exists, and every vendored file is byte-identical to upstream.
3. `tools/verify_no_standalone_cnc_semantics.sh`
   Confirms standalone code has not introduced project-owned `Interp::...`
   member definitions outside the documented Python/remap runtime-edge stubs.
4. `tools/verify_native_linuxcnc_fixture_baseline.sh`
   Runs a side-by-side fixture baseline through upstream
   `../linuxcnc/bin/rs274` and compares normalized canonical events for
   fixtures that do not require standalone-only runtime adapters.
5. `tools/build_native_probes.sh`
   Builds native source probes and standalone harnesses from vendored
   LinuxCNC source plus narrow runtime wrappers.
6. `tests/native/verify_native_probes.sh`
   Checks probe exit codes, source-probe coverage, harness stdout, canonical
   fixture events, and expected error behavior.

The WASM INI smoke script builds `runtime/ui/ini-panel/linuxcnc_ini.js` and
`linuxcnc_ini.wasm` from vendored LinuxCNC `inifile.cc`, then loads that
module through `runtime/sdk/src/index.js` in Node and verifies INI string and
boolean queries against a file written to the Emscripten filesystem. Boolean
conversion is validated through vendored LinuxCNC `iniFindBool()`, and
machine-session file-name lookup is validated through LinuxCNC string queries
for `[RS274NGC]PARAMETER_FILE` and `[EMCIO]TOOL_TABLE`.

The WASM interpreter-core smoke script builds
`build/wasm/core/linuxcnc_interp.js` and `linuxcnc_interp.wasm` from the same
vendored LinuxCNC interpreter source set used by the native minimal
interpreter harness. It loads the module in Node through
`runtime/sdk/src/index.js`, runs the first WASM interpreter fixture
group through `Interp::execute()`, and compares emitted canonical events plus
required LinuxCNC `_setup` state readback with the matching files in
`tests/fixtures/canon/`. It also calls vendored `Interp::init()` and
`Interp::synch()` through the WASM C ABI to validate the initialization
canonical boundary, metric/inch machine-unit status edge, and current/selected
tool slot status synchronization already covered by the native init harness.
It also calls the vendored single-axis rotary indexer path through
`Interp::execute()` to validate the `UNLOCK_ROTARY`/`LOCK_ROTARY` canonical
runtime boundary already covered by the native indexer harness.
It also calls vendored `Interp::init_named_parameters()` and
`Interp::find_named_param()` through the WASM C ABI to validate the native
named-parameter harness path for LinuxCNC built-in, INI-backed, HAL-backed,
and missing named-parameter lookup.
It also writes selected G-code fixtures into the
Emscripten filesystem through the SDK and runs them through LinuxCNC
`Interp::open()`, `Interp::read()`, and `Interp::execute()` to validate the
file execution path. The same Node smoke writes LinuxCNC-format parameter
files into the Emscripten filesystem and validates vendored
`Interp::restore_parameters()` and `Interp::save_parameters()`, including the
saved parameter values, missing required numeric parameter defaulting, and the
`.bak` backup file boundary. It also writes the
negative G-code fixtures into the Emscripten filesystem and verifies their
LinuxCNC-produced error text through the `Interp::open()`/`read()`/`execute()`
file path.

The OPFS host-boundary script validates the JavaScript file-service adapter
with a Node mock of the browser File System Access handles. It covers nested
directory creation, text save/load, missing file behavior, invalid relative
paths, unavailable OPFS storage, and the host-side OPFS path model for INI,
tool table, parameter, G-code, preview-cache, and session-snapshot storage
targets. It also validates the host-side session snapshot JSON envelope and
round-trip store, including unsupported format/version, session-id mismatch,
non-object metadata/payload rejection, custom snapshot filenames, and invalid
snapshot filename rejection, plus pure-text machine file and G-code stores,
including G-code program filename rejection for traversal or nested paths,
without defining CNC machine-state or file-format semantics. It now also validates the
OPFS-to-WASM parameter-file bridge with a mock interpreter SDK to ensure the
host boundary copies text into and out of the WASM filesystem without defining
parameter semantics, and that INI-derived machine file names are still
rejected by the OPFS path model when they contain traversal or nested path
segments. The same Node smoke also validates that explicit session file-name
options take precedence over INI-derived parameter and tool-table file names,
and that missing INI file-name values fall back to the host path model defaults,
keeping host override policy outside CNC semantics.

The browser INI/OPFS smoke script serves `wasm-port/` over localhost and runs
Chromium headless against a test page that imports the JS SDK, loads the INI
WASM module, queries vendored LinuxCNC INI parsing through the SDK, including
machine-session parameter/tool-table file-name strings, and performs an OPFS
text-file, generic session snapshot, custom snapshot filename, invalid
snapshot filename/envelope, machine file, G-code text round trip, and G-code
filename path-model rejection. It also verifies that the INI panel UI exposes
the default OPFS parameter-file and tool-table mappings used when a machine
session is copied into the interpreter WASM filesystem.

The browser interpreter smoke script serves `wasm-port/` over localhost and
runs Chromium headless against a test page that loads the interpreter-core
WASM module through `runtime/sdk/src/index.js`, writes no CNC
behavior in JavaScript, and verifies existing canonical fixtures through the
exported C ABI backed by vendored LinuxCNC `Interp::execute()` and
`Interp::open()`/`read()`/`execute()` paths, including the INI-aware
named-parameter file path and negative interpreter fixtures with expected
error text plus absent canonical motion output. It also validates vendored
`Interp::init()` and `Interp::synch()` through the same SDK/C ABI path,
including initialization canonical events, metric/inch machine units, and tool
slot readback, and checks the vendored rotary-indexer `G0 A...` execution path
for `UNLOCK_ROTARY`/`LOCK_ROTARY` boundary events. It also validates
`Interp::init_named_parameters()` and `Interp::find_named_param()` through the
same browser SDK/C ABI path for built-in, INI-backed, HAL-backed, and missing
named-parameter lookup. It also uses real browser OPFS
storage plus the interpreter SDK to restore and save a LinuxCNC parameter file
through vendored `Interp::restore_parameters()` and `Interp::save_parameters()`,
and directly checks missing-file success plus out-of-order parameter-file
rejection through the same LinuxCNC `restore_parameters()` C ABI,
to load/save LinuxCNC tool tables through vendored `tooldata_common.cc`, and
to check the random-toolchanger `tooldata_save()` result before OPFS text
writeback,
to reject invalid INI-derived parameter/tool-table file names through the OPFS
path model after the names are parsed by the LinuxCNC-backed INI WASM SDK. It
also verifies that explicit session parameter/tool-table file-name options
override INI-derived names before OPFS text is copied into the LinuxCNC-backed
WASM filesystem, and that absent INI file-name values use the default OPFS
parameter/tool-table paths in a real browser session.

The aggregate host smoke script builds the INI and interpreter-core WASM
artifacts once, then runs the Node WASM smokes, the Node OPFS mock smoke, and
the Chromium browser smokes.

## Source Coverage

Every `.c` and `.cc` entry in `tools/source-manifest.txt` must have a
corresponding `*_source_probe` entry in `build/native/source-probes.tsv`.
The validation fails if:

- a manifest source file lacks a source probe;
- a source probe references a file not listed in the manifest;
- a manifest file is duplicated;
- vendored files drift byte-for-byte from upstream LinuxCNC.

## Current Native Harnesses

| Harness | Purpose |
| --- | --- |
| `linuxcnc_ini_probe` | Validates vendored LinuxCNC INI parsing can be used standalone. |
| `linuxcnc_interp_state_probe` | Validates interpreter state constants and structs compile under the standalone boundary. |
| `linuxcnc_emc_status_probe` | Validates the standalone `emcStatus` machine-units status boundary used by vendored interpreter conversion and initialization code. |
| `linuxcnc_namedparam_harness` | Validates LinuxCNC named parameter behavior, `_ini[...]`, and `_hal[...]` adapter resolution. |
| `linuxcnc_interp_minimal_harness` | Runs G-code fixtures through vendored LinuxCNC parser/execution/conversion code, captures canonical events, and validates feed-rate state readback across length-unit changes. |
| `linuxcnc_parameter_file_harness` | Validates LinuxCNC parameter file restore/save behavior and required/read-only parameter handling. |
| `linuxcnc_interp_init_harness` | Validates vendored LinuxCNC `Interp::init()` emits canonical initialization boundaries, reads metric/inch machine units, and synchronizes current/selected tool slots through standalone status adapters. |
| `linuxcnc_indexer_harness` | Validates vendored LinuxCNC single-axis rotary indexer dispatch emits lock/unlock and motion boundaries through the standalone event sink. |
| `linuxcnc_tp_api_probe` | Validates vendored LinuxCNC trajectory planner calls for linear, arc, and queued motion paths. |
| `linuxcnc_kinematics_probe` | Validates vendored LinuxCNC `trivkins.c` plus `kins_util.c` initialize and perform identity forward/inverse mapping through the standalone HAL/RTAPI boundary. |
| `linuxcnc_5axis_kinematics_probe` | Validates vendored LinuxCNC `5axiskins.c` through `switchkins.c`, including 5-axis forward/inverse round-trip behavior and switching to identity kinematics. |
| `linuxcnc_xyzac_trt_kinematics_probe` | Validates vendored LinuxCNC XYZAC TRT kinematics through `switchkins.c`, including forward/inverse round-trip behavior and switching to identity kinematics. |
| `linuxcnc_xyzbc_trt_kinematics_probe` | Validates vendored LinuxCNC XYZBC TRT kinematics through `switchkins.c`, including forward/inverse round-trip behavior and switching to identity kinematics. |
| `linuxcnc_corexy_kinematics_probe` | Validates vendored LinuxCNC CoreXY forward/inverse behavior through the standalone HAL/RTAPI boundary. |
| `linuxcnc_rotate_kinematics_probe` | Validates vendored LinuxCNC rotated-axis forward/inverse behavior. |
| `linuxcnc_rose_kinematics_probe` | Validates vendored LinuxCNC rose kinematics forward/inverse behavior. |
| `linuxcnc_max_kinematics_probe` | Validates vendored LinuxCNC max kinematics forward/inverse behavior. |
| `linuxcnc_lineardelta_kinematics_probe` | Validates vendored LinuxCNC linear-delta inverse/forward pose round-trip behavior. |
| `linuxcnc_rotarydelta_kinematics_probe` | Validates vendored LinuxCNC rotary-delta inverse/forward pose round-trip behavior. |
| `linuxcnc_scorbot_kinematics_probe` | Validates vendored LinuxCNC Scorbot forward/inverse behavior and pose round-trip behavior. |
| `linuxcnc_tripod_kinematics_probe` | Validates vendored LinuxCNC tripod inverse/forward behavior, including below-platform flag behavior. |
| `linuxcnc_scara_kinematics_probe` | Validates vendored LinuxCNC SCARA forward/inverse behavior and switching to identity kinematics. |
| `linuxcnc_puma_kinematics_probe` | Validates vendored LinuxCNC PUMA forward/inverse behavior, pose round-trip behavior, and switching to identity kinematics. |
| `linuxcnc_genser_kinematics_probe` | Validates vendored LinuxCNC generic serial kinematics forward/inverse behavior and switching to identity kinematics. |
| `linuxcnc_genhex_kinematics_probe` | Validates vendored LinuxCNC generic hexapod inverse/forward behavior, including the switchkins iterative-forward warmup path. |
| `linuxcnc_pentakins_kinematics_probe` | Validates vendored LinuxCNC pentapod inverse/forward pose round-trip behavior. |

## Current WASM Harnesses

| Harness | Purpose |
| --- | --- |
| `tests/wasm/node/verify_ini_wasm.sh` | Validates the browser-facing INI WASM module can be built from vendored LinuxCNC `inifile.cc`, loaded through the JS SDK in Node, and queried through the exported C ABI, including LinuxCNC-backed boolean conversion and machine-session file-name string lookup. |
| `tests/wasm/node/verify_interp_wasm.sh` | Validates the initial interpreter-core WASM module can be built from vendored LinuxCNC interpreter source, loaded through the interpreter JS SDK, run the first fixture group through `Interp::execute()` and selected file fixtures through `Interp::open()`/`read()`/`execute()`, match the native canonical event plus required state readback fixtures, and run parameter-file restore/save through vendored LinuxCNC `Interp::restore_parameters()` and `Interp::save_parameters()`. |
| `tests/opfs/node/verify_file_service.sh` | Validates the host-owned OPFS text-file adapter, path model, session snapshot store including custom filenames and envelope/path rejection paths, machine file store, G-code text store including filename rejection paths, OPFS-to-WASM parameter/tool-table bridges, and grouped machine-session loading without moving file persistence, parameter semantics, or tool-table semantics into the WASM core. |
| `tests/browser/verify_ini_panel_browser.sh` | Validates the INI SDK, INI/interpreter WASM module loading, LinuxCNC-backed INI machine-session file-name string lookup, OPFS text-file round trip, generic session snapshot round trip plus custom filename and envelope/path rejection paths, machine file text round trip, G-code text round trip plus filename rejection paths, and the INI panel UI's machine-session load with default OPFS parameter/tool-table file mapping, G-code run, and canonical-event display paths in a real browser runtime. |
| `tests/browser/verify_interp_browser.sh` | Validates the interpreter-core WASM module loads through the interpreter JS SDK in a real browser runtime and runs selected positive and negative canonical fixtures through vendored LinuxCNC `Interp::execute()` plus `Interp::open()`/`read()`/`execute()` via the exported C ABI, including OPFS-backed parameter-file restore/save and non-random/random tool-table load/save through vendored LinuxCNC source. |
| `tests/host/verify_host_smokes.sh` | Runs the current host-side Node, WASM interpreter-core, OPFS, and browser smoke validation with shared WASM builds. |

## Fixture Coverage

Positive G-code fixtures currently cover:

- linear traverse/feed
- arc semantics
- modal absolute/incremental motion
- position parameters
- canned cycles
- coordinate offsets
- G53 machine-coordinate motion
- feed and motion control modes
- probing
- threading and rigid tap
- NURBS G5/G6
- spindle orient
- tool semantics
- tool table setup
- tool-data reload boundary
- interpreter state-tag boundary
- percent-delimited file `FINISH` boundary
- file-open `ON_RESET` boundary
- comment logging canonical calls
- named and numbered parameters
- O-word subroutines
- program-end modal reset
- canonical runtime edge calls

Negative fixtures currently cover:

- zero-feed `G1`
- arc radius mismatch
- zero-radius arc
- G53 incremental-mode rejection
- read-only named parameter writes
- read-only numbered parameter writes
- missing tool
- missing tool length offset

## Validation Boundaries

Current full-core validation is native-only. WASM/SDK validation covers the
INI parser smoke harness and an initial interpreter-core canonical event smoke
for `minimal_linear`, `arc_semantics`, `length_units`, `modal_incremental`,
`plane_selection`, `coordinate_offsets`, `g53_machine_coordinates`,
`feed_control_modes`, `position_params`, `probe_semantics`, `spindle_orient`,
`comment_logging`, `numbered_params`, `tool_semantics`, `tool_table_setup`,
`tool_reload`, `canned_cycles`, `cutter_comp_motion`, `threading_sync`,
`nurbs_g5_semantics`, `nurbs_g6_semantics`, `state_tag_motion`,
`canon_runtime_edges`, `program_end_modal_reset`, and `namedparam_semantics`
through both Node WASM and browser INI-aware program ABI smoke coverage,
plus the `g1_zero_feed`, `arc_radius_mismatch`, `arc_zero_radius`,
`cutter_comp_plane_change`, `g53_incremental`, `namedparam_readonly`,
`numbered_param_readonly`, `tool_not_found`, and
`tool_length_offset_not_found` negative fixtures. The WASM interpreter file
path additionally covers the same canonical-event fixture group, plus
`namedparam_semantics` through the INI-aware file execution ABI,
`file_open_reset`, `percent_file_finish`, and `oword_subroutine`.
`position_params` uses a dedicated file-path expectation under
`tests/fixtures/canon_file/` because LinuxCNC file execution advances the
post-execute position parameters differently than the line-by-line MDI smoke.
The same Node WASM and browser file-path smokes also cover the negative fixture
group and check the LinuxCNC file-execution error text plus absent canonical
motion constraints where applicable.
The Node WASM and browser interpreter smokes also cover LinuxCNC parameter-file
restore/save behavior through the exported C ABI, including out-of-order file
rejection, missing-file success, missing required numeric parameter defaulting,
required numeric parameter writeback, removal of named-parameter-only lines
from saved output, and the `.bak` backup produced by vendored
`save_parameters()`, including browser OPFS readback of the backup text after
the host bridge writes it to persistent storage. It also covers LinuxCNC tool-table
load/save behavior through vendored `tooldata_common.cc`, including the
non-random and random-toolchanger `tooldata_init()` branches, with the SDK
only copying text into the Emscripten filesystem and calling the exported C
ABI; the browser smoke checks the random-toolchanger `tooldata_save()` C ABI
result before OPFS persistence writes the saved table text back, and verifies
that an INI-derived custom tool-table OPFS path can be saved and read back
after the table is loaded through vendored LinuxCNC. The same
Node WASM and browser interpreter smokes now validate the exported
`Interp::init()`/`Interp::synch()` probe for initialization canonical events,
metric/inch `emcStatus` machine-unit conversion, and current/selected tool
slot synchronization. They also validate the exported rotary-indexer probe for
vendored LinuxCNC `UNLOCK_ROTARY`/`LOCK_ROTARY` dispatch around a single-axis
`G0 A...` move, plus the exported named-parameter probe for direct LinuxCNC
`init_named_parameters()` and `find_named_param()` lookup of built-in,
INI-backed, HAL-backed, and missing named parameters.
OPFS validation covers the JavaScript host-boundary adapter, the INI browser
smoke harness, the INI panel UI's machine-session load and G-code run buttons,
the raw canonical-event display fed directly by LinuxCNC interpreter WASM
output, the Node parameter/tool-table bridges that copy OPFS text through the
SDK into vendored LinuxCNC file APIs, the Node machine-session bridge that
groups INI, parameter, and tool-table loading, the random-toolchanger flag
derived from vendored LinuxCNC INI boolean parsing, INI-derived
`[RS274NGC]PARAMETER_FILE` and `[EMCIO]TOOL_TABLE` file names mapped to OPFS
machine files, OPFS path-model rejection of invalid INI-derived file names,
explicit host session file-name overrides taking precedence over INI-derived
names, default host path fallback when INI file-name values are absent,
session snapshot custom filename handling plus envelope/path rejection
for unsupported format/version, wrong session id, and invalid snapshot
filenames, and a browser interpreter smoke that uses the same session bridge
with real LinuxCNC INI WASM parsing before saving OPFS-backed parameter and
tool-table text through vendored LinuxCNC file APIs, including default OPFS
path fallback when INI file-name values are absent.
Full browser coverage, full SDK coverage, and richer machine-state validation
remain future work.

## WASM/Browser Fixture Matrix

The executable fixture lists for Node WASM and browser interpreter smoke tests
are centralized in `tests/fixtures/interp-fixture-matrix.mjs`. Additions to the
matrix must continue to route execution through the SDK and exported C ABI
backed by vendored LinuxCNC interpreter code; the matrix is only a test
coverage list, not a CNC behavior implementation.

Node WASM `Interp::execute()` coverage currently includes:

- `minimal_linear`
- `arc_semantics`
- `length_units`
- `modal_incremental`
- `plane_selection`
- `coordinate_offsets`
- `g53_machine_coordinates`
- `feed_control_modes`
- `position_params`
- `probe_semantics`
- `spindle_orient`
- `comment_logging`
- `numbered_params`
- `tool_semantics`
- `tool_table_setup`
- `tool_reload`
- `canned_cycles`
- `cutter_comp_motion`
- `threading_sync`
- `nurbs_g5_semantics`
- `nurbs_g6_semantics`
- `state_tag_motion`
- `canon_runtime_edges`
- `program_end_modal_reset`
- `namedparam_semantics` through the INI-aware program ABI

Node WASM file-path coverage currently includes:

- `minimal_linear`
- `arc_semantics`
- `length_units`
- `modal_incremental`
- `plane_selection`
- `coordinate_offsets`
- `g53_machine_coordinates`
- `feed_control_modes`
- `probe_semantics`
- `spindle_orient`
- `comment_logging`
- `numbered_params`
- `tool_semantics`
- `tool_table_setup`
- `tool_reload`
- `canned_cycles`
- `cutter_comp_motion`
- `threading_sync`
- `nurbs_g5_semantics`
- `nurbs_g6_semantics`
- `state_tag_motion`
- `canon_runtime_edges`
- `program_end_modal_reset`
- `file_open_reset`
- `percent_file_finish`
- `oword_subroutine`
- `position_params` through the dedicated `canon_file/` expectation
- `namedparam_semantics` through the INI-aware file ABI

Node WASM file-path negative coverage currently includes every fixture under
`tests/fixtures/gcode_errors/`:

- `g1_zero_feed`
- `arc_radius_mismatch`
- `arc_zero_radius`
- `cutter_comp_plane_change`
- `g53_incremental`
- `namedparam_readonly`
- `numbered_param_readonly`
- `tool_length_offset_not_found`
- `tool_not_found`

Browser interpreter file-path negative coverage currently includes the same
negative fixture list through `Interp::open()`/`read()`/`execute()`:

- `g1_zero_feed`
- `arc_radius_mismatch`
- `arc_zero_radius`
- `cutter_comp_plane_change`
- `g53_incremental`
- `namedparam_readonly`
- `numbered_param_readonly`
- `tool_length_offset_not_found`
- `tool_not_found`

Browser interpreter `Interp::execute()` coverage currently includes:

- `minimal_linear`
- `arc_semantics`
- `length_units`
- `modal_incremental`
- `plane_selection`
- `coordinate_offsets`
- `g53_machine_coordinates`
- `feed_control_modes`
- `position_params`
- `canned_cycles`
- `numbered_params`
- `comment_logging`
- `tool_semantics`
- `tool_table_setup`
- `probe_semantics`
- `spindle_orient`
- `cutter_comp_motion`
- `threading_sync`
- `nurbs_g5_semantics`
- `nurbs_g6_semantics`
- `state_tag_motion`
- `canon_runtime_edges`
- `tool_reload`
- `program_end_modal_reset`
- `namedparam_semantics` through the INI-aware program ABI

Browser interpreter negative coverage currently includes every fixture under
`tests/fixtures/gcode_errors/`:

- `g1_zero_feed`
- `arc_radius_mismatch`
- `arc_zero_radius`
- `g53_incremental`
- `cutter_comp_plane_change`
- `namedparam_readonly`
- `numbered_param_readonly`
- `tool_length_offset_not_found`
- `tool_not_found`

Browser interpreter file-path coverage currently includes the same
`INTERP_FILE_FIXTURES` list as the Node WASM smoke:

- `minimal_linear`
- `arc_semantics`
- `length_units`
- `modal_incremental`
- `plane_selection`
- `coordinate_offsets`
- `g53_machine_coordinates`
- `feed_control_modes`
- `probe_semantics`
- `spindle_orient`
- `comment_logging`
- `numbered_params`
- `tool_semantics`
- `tool_table_setup`
- `tool_reload`
- `canned_cycles`
- `cutter_comp_motion`
- `threading_sync`
- `nurbs_g5_semantics`
- `nurbs_g6_semantics`
- `state_tag_motion`
- `canon_runtime_edges`
- `program_end_modal_reset`
- `file_open_reset`
- `percent_file_finish`
- `oword_subroutine`
- `position_params` through the dedicated `canon_file/` expectation
- `namedparam_semantics` through the INI-aware file ABI

All current positive G-code fixtures have browser interpreter smoke coverage
through either `Interp::execute()`, the file-path ABI, or the INI-aware
file-path ABI.

The current fixture expectations validate standalone behavior against both the
vendored LinuxCNC source path and an upstream `rs274` side-by-side baseline for
parser/conversion, arc geometry, offsets, feed-control and feed-state
readback, comment/logging,
numbered-parameter, probing, spindle-orient, file-open reset, file-finish,
tool-reload, tool select/change/length-offset, canned-cycle, state-tag motion,
tool-table setup, and O-word subroutine fixtures, plus threading/rigid tap,
NURBS dispatch boundaries, and the comparable canonical runtime edge and
program-end cleanup calls. Fixtures that depend on standalone-only runtime
adapters, HAL/INI/tool-change state, upstream `rs274` output gaps such as
`WAIT` or hidden NURBS control-point detail, or richer machine session state
still need dedicated native LinuxCNC baselines.

Remaining positive fixtures that are not in the upstream `rs274` side-by-side
baseline are intentionally held out until they get a dedicated native LinuxCNC
baseline: `namedparam_semantics` depends on standalone INI/HAL adapter
resolution. `state_tag_motion` now compares its motion events with upstream
`rs274`, while `UPDATE_TAG` events remain a standalone state-tag capture
boundary. `tool_semantics` now compares T/M6/G43/G49 canonical events with
upstream `rs274`; M61 current-pocket host-state behavior remains covered by the
standalone fixture expectation, and `Interp::synch()` current/selected tool
slot reads are covered by the native init harness.

The kinematics probes currently cover LinuxCNC identity/trivial kinematics, the
switchable `5axiskins` XYZBCW bridge-mill model, TRT `xyzac`/`xyzbc`
table-rotary models, CoreXY, rotated-axis, rose, max, linear-delta,
rotary-delta, Scorbot, tripod, SCARA, PUMA, generic serial, generic hexapod,
and pentapod models.