继续按 align-linuxcnc 约束：补参数读取错误源码覆盖

结论：新增参数索引、命名参数终止和实数读取错误 fixture，全部绑定 LinuxCNC interp_read.cc 的 source-link 断言；未扩展 smoke。

test-linuxcnc-source-link.sh

@@ -577,6 +577,29 @@ for case in "${parameter_setting_error_cases[@]}"; do
     fi
     grep -q "$expected" "$output_dir/cnc_sim_linuxcnc_source_$fixture.err"
 done
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc
+# read_parameter(), read_parameter_setting(), read_integer_value(),
+# read_name(), and read_real_value() reject malformed parameter indices,
+# unterminated named parameters, and missing or malformed real values.
+parameter_reader_error_cases=(
+    "linuxcnc_parameter_number_out_of_range_error|Parameter number out of range"
+    "linuxcnc_parameter_reference_out_of_range_error|Parameter number out of range"
+    "linuxcnc_non_integer_parameter_index_error|Non integer value for integer"
+    "linuxcnc_named_parameter_not_terminated_error|Named parameter not terminated"
+    "linuxcnc_no_real_value_error|No characters found in reading real value"
+    "linuxcnc_bad_number_format_error|bad number format (conversion failed) parsing '+'"
+)
+for case in "${parameter_reader_error_cases[@]}"; do
+    fixture=${case%%|*}
+    expected=${case#*|}
+    if CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" \
+        "$build_dir/linuxcnc_rs274_source_dump" "tests/gcode/$fixture.ngc" \
+        >"$output_dir/cnc_sim_linuxcnc_source_$fixture.json" 2>"$output_dir/cnc_sim_linuxcnc_source_$fixture.err"; then
+        echo "expected $fixture.ngc to fail" >&2
+        exit 1
+    fi
+    grep -q "$expected" "$output_dir/cnc_sim_linuxcnc_source_$fixture.err"
+done
 if CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" \
     "$build_dir/linuxcnc_rs274_source_dump" tests/gcode/linuxcnc_negative_sqrt_error.ngc \
     >"$output_dir/cnc_sim_linuxcnc_source_negative_sqrt_error.json" 2>"$output_dir/cnc_sim_linuxcnc_source_negative_sqrt_error.err"; then