按建议，继续工作

结论：已新增 G53 机床坐标正向 fixture 和增量模式拒绝 fixture，固定 vendored LinuxCNC find_ends()/convert_straight() 行为；native probe 全量验证通过。

wasm-port/docs/compatibility-validation.md

@@ -67,6 +67,7 @@ Positive G-code fixtures currently cover:
 - position parameters
 - canned cycles
 - coordinate offsets
+- G53 machine-coordinate motion
 - feed and motion control modes
 - probing
 - threading and rigid tap
@@ -84,6 +85,7 @@ 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

wasm-port/docs/porting-steps-standalone.md

@@ -402,6 +402,13 @@ Current verified progress:
   `tests/fixtures/canon/cutter_comp_motion.events` pin positive `G41.1`/`G40`
   compensated straight-feed output through vendored `interp_convert.cc` and
   `interp_queue.cc`.
+- `tests/fixtures/gcode/g53_machine_coordinates.ngc` and
+  `tests/fixtures/canon/g53_machine_coordinates.events` pin `G53` machine
+  coordinate straight-traverse behavior through vendored
+  `interp_find.cc::find_ends()` and `interp_convert.cc::convert_straight()`.
+  `tests/fixtures/gcode_errors/g53_incremental.ngc` and
+  `tests/fixtures/canon_errors/g53_incremental.expected` pin the LinuxCNC
+  rejection path for `G53` while incremental distance mode is active.
 - `runtime/core/linuxcnc_wrap/linuxcnc_interp_minimal_runtime.cpp` now records
   feed/control canonical boundary calls emitted by vendored LinuxCNC
   conversion and queue code: `SET_TRAVERSE_RATE`, `SET_FEED_REFERENCE`,

wasm-port/docs/scope-and-baseline.md

@@ -40,6 +40,7 @@ G-code fixture coverage includes:
 - position parameters
 - canned cycles
 - coordinate offsets
+- G53 machine-coordinate motion
 - feed and motion control modes
 - cutter compensation motion
 - probe semantics
@@ -58,6 +59,7 @@ Negative fixture coverage includes:
 - arc radius mismatch
 - zero-radius arc
 - cutter compensation plane-change rejection
+- G53 incremental-mode rejection
 - read-only named parameter writes
 - read-only numbered parameter writes
 - missing tool