diff --git a/wasm-port/docs/porting-steps-standalone.md b/wasm-port/docs/porting-steps-standalone.md
index eff1b42..574a655 100644
--- a/wasm-port/docs/porting-steps-standalone.md
+++ b/wasm-port/docs/porting-steps-standalone.md
@@ -354,6 +354,12 @@ Current verified progress:
 - The same validation is now fixture-driven through
   `tests/fixtures/gcode/minimal_linear.ngc` and
   `tests/fixtures/canon/minimal_linear.events`.
+- `tests/fixtures/gcode/modal_incremental.ngc` and
+  `tests/fixtures/canon/modal_incremental.events` add `G90`/`G91`
+  distance-mode switching plus modal `G1` carry-forward coverage. The
+  temporary wrapper behavior is based on LinuxCNC
+  `interp_convert.cc::convert_distance_mode()` and
+  `interp_convert.cc::convert_straight()`.
 - This proves the current extracted interpreter slice can parse and execute a
   simple traverse and feed move through a standalone canonical event sink.
 
@@ -654,8 +660,9 @@ Keep these documents under `wasm-port/docs/`:
 Continue expanding the standalone interpreter core from the verified minimal
 traverse path:
 
-1. add another fixture for incremental mode and modal carry-forward,
-2. replace the temporary minimal `convert_g()` implementation with thin
+1. replace the temporary minimal `convert_g()` implementation with thin
    wrappers around more vendored interpreter conversion code,
+2. add fixture coverage for `Z` moves and multi-axis current-position
+   parameter updates,
 3. keep all source changes inside `wasm-port/` and leave `../linuxcnc/`
    read-only.
diff --git a/wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_interp_minimal_runtime.cpp b/wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_interp_minimal_runtime.cpp
index 46deedc..2d7bb24 100644
--- a/wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_interp_minimal_runtime.cpp
+++ b/wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_interp_minimal_runtime.cpp
@@ -351,27 +351,40 @@ bool Interp::is_any_m_code_remapped(block_pointer, setup_pointer) { return false
 int Interp::convert_m(block_pointer, setup_pointer) { return INTERP_OK; }
 int Interp::convert_g(block_pointer block, setup_pointer settings)
 {
+    const int distance_mode = block->g_modes[GM_DISTANCE_MODE];
+    if (distance_mode == G_90) {
+        settings->distance_mode = DISTANCE_MODE::ABSOLUTE;
+    } else if (distance_mode == G_91) {
+        settings->distance_mode = DISTANCE_MODE::INCREMENTAL;
+    }
+
     if (block->f_flag) {
         settings->feed_rate = block->f_number;
         SET_FEED_RATE(block->f_number);
     }
 
+    const bool incremental = settings->distance_mode == DISTANCE_MODE::INCREMENTAL;
     if (block->x_flag) {
-        settings->current_x = block->x_number;
+        settings->current_x = incremental ? settings->current_x + block->x_number
+                                          : block->x_number;
     }
     if (block->y_flag) {
-        settings->current_y = block->y_number;
+        settings->current_y = incremental ? settings->current_y + block->y_number
+                                          : block->y_number;
     }
     if (block->z_flag) {
-        settings->current_z = block->z_number;
+        settings->current_z = incremental ? settings->current_z + block->z_number
+                                          : block->z_number;
     }
 
     if (block->motion_to_be == G_0) {
+        settings->motion_mode = G_0;
         STRAIGHT_TRAVERSE(block->line_number,
                           settings->current_x, settings->current_y, settings->current_z,
                           settings->AA_current, settings->BB_current, settings->CC_current,
                           settings->u_current, settings->v_current, settings->w_current);
     } else if (block->motion_to_be == G_1) {
+        settings->motion_mode = G_1;
         STRAIGHT_FEED(block->line_number,
                       settings->current_x, settings->current_y, settings->current_z,
                       settings->AA_current, settings->BB_current, settings->CC_current,
diff --git a/wasm-port/tests/fixtures/canon/modal_incremental.events b/wasm-port/tests/fixtures/canon/modal_incremental.events
new file mode 100644
index 0000000..4401130
--- /dev/null
+++ b/wasm-port/tests/fixtures/canon/modal_incremental.events
@@ -0,0 +1,5 @@
+canon_event=STRAIGHT_TRAVERSE line=1 x=1 y=1 z=0 a=0 b=0 c=0 u=0 v=0 w=0
+canon_event=SET_FEED_RATE rate=60
+canon_event=STRAIGHT_FEED line=2 x=3 y=1 z=0 a=0 b=0 c=0 u=0 v=0 w=0
+canon_event=STRAIGHT_FEED line=3 x=3 y=4 z=0 a=0 b=0 c=0 u=0 v=0 w=0
+canon_event=STRAIGHT_TRAVERSE line=4 x=0 y=0 z=0 a=0 b=0 c=0 u=0 v=0 w=0
diff --git a/wasm-port/tests/fixtures/gcode/modal_incremental.ngc b/wasm-port/tests/fixtures/gcode/modal_incremental.ngc
new file mode 100644
index 0000000..7043268
--- /dev/null
+++ b/wasm-port/tests/fixtures/gcode/modal_incremental.ngc
@@ -0,0 +1,4 @@
+G90 G0 X1.0 Y1.0
+G91 G1 X2.0 F60.0
+G1 Y3.0
+G90 G0 X0.0 Y0.0
diff --git a/wasm-port/tests/native/verify_native_probes.sh b/wasm-port/tests/native/verify_native_probes.sh
index 248147f..b7dda83 100755
--- a/wasm-port/tests/native/verify_native_probes.sh
+++ b/wasm-port/tests/native/verify_native_probes.sh
@@ -3,7 +3,8 @@ set -euo pipefail
 
 ROOT_DIR="$(cd "$(dirname "$0")/../.." && pwd)"
 BUILD_DIR="$ROOT_DIR/build/native"
-EXPECTED_EVENTS="$ROOT_DIR/tests/fixtures/canon/minimal_linear.events"
+GCODE_FIXTURE_DIR="$ROOT_DIR/tests/fixtures/gcode"
+CANON_FIXTURE_DIR="$ROOT_DIR/tests/fixtures/canon"
 
 "$ROOT_DIR/tools/build_native_probes.sh"
 
@@ -33,16 +34,47 @@ check_exitcode linuxcnc_interp_minimal_harness
 check_exitcode linuxcnc_interp_minimal_harness.run
 check_exitcode linuxcnc_rs274_compile_probe
 
+check_fixture_output() {
+  local fixture="$1"
+  local expected="$2"
+  local stdout_file="$3"
+
+  grep -Fq "read=0" "$stdout_file"
+  grep -Fq "parse_line=0" "$stdout_file"
+
+  local line_count
+  line_count="$(grep -cv '^[[:space:]]*$' "$fixture")"
+  local line_number
+  for ((line_number = 1; line_number <= line_count; line_number += 1)); do
+    grep -Fq "execute_line_${line_number}=0" "$stdout_file"
+  done
+
+  while IFS= read -r expected_event; do
+    [[ -z "$expected_event" ]] && continue
+    grep -Fq "$expected_event" "$stdout_file"
+  done < "$expected"
+}
+
 RUN_STDOUT="$BUILD_DIR/linuxcnc_interp_minimal_harness.run.stdout.log"
+check_fixture_output \
+  "$GCODE_FIXTURE_DIR/minimal_linear.ngc" \
+  "$CANON_FIXTURE_DIR/minimal_linear.events" \
+  "$RUN_STDOUT"
 
-grep -Fq "read=0" "$RUN_STDOUT"
-grep -Fq "execute_line_1=0" "$RUN_STDOUT"
-grep -Fq "execute_line_2=0" "$RUN_STDOUT"
-grep -Fq "parse_line=0" "$RUN_STDOUT"
+for fixture in "$GCODE_FIXTURE_DIR"/*.ngc; do
+  name="$(basename "$fixture" .ngc)"
+  expected="$CANON_FIXTURE_DIR/$name.events"
+  if [[ ! -f "$expected" ]]; then
+    echo "missing expected canon fixture: $expected" >&2
+    exit 1
+  fi
 
-while IFS= read -r expected_event; do
-  [[ -z "$expected_event" ]] && continue
-  grep -Fq "$expected_event" "$RUN_STDOUT"
-done < "$EXPECTED_EVENTS"
+  stdout_file="$BUILD_DIR/linuxcnc_interp_minimal_harness.$name.stdout.log"
+  stderr_file="$BUILD_DIR/linuxcnc_interp_minimal_harness.$name.stderr.log"
+  "$BUILD_DIR/linuxcnc_interp_minimal_harness" "$fixture" \
+    >"$stdout_file" \
+    2>"$stderr_file"
+  check_fixture_output "$fixture" "$expected" "$stdout_file"
+done
 
 echo "native probe validation complete"