cnc_wams/wasm-port/docs/compatibility-validation.md

# 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 validation command is:

```bash
wasm-port/tests/native/verify_native_probes.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 reintroduced `Interp::convert_g()`.
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.

## 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_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 and captures canonical events. |
| `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 through the standalone event sink. |
| `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. |

## 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 validation is native-only. WASM, browser, SDK, OPFS, and full
machine-session validation remain future work.

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, offsets, feed-control, comment/logging, numbered-parameter,
spindle-orient, file-open reset, file-finish, tool-reload, and O-word
subroutine fixtures, plus threading/rigid tap and the comparable canonical
runtime edge calls. Fixtures that depend on standalone-only runtime adapters,
HAL/INI/tool table setup, upstream `rs274` output gaps such as `WAIT`, or
richer machine session state still need dedicated native LinuxCNC baselines.

The kinematics probes currently cover LinuxCNC identity/trivial kinematics,
the switchable `5axiskins` XYZBCW bridge-mill model, and the TRT `xyzac`/`xyzbc`
table-rotary models. Serial, delta, SCARA, and other machine-specific
kinematics still need dedicated baselines.