继续按 align-linuxcnc 约束：补注释前缀控制字源码覆盖，测试通过

test-linuxcnc-source-link.sh

@@ -765,11 +765,15 @@ fi
 grep -Fq "Multiple spindle choice (\$) words on one line" \
     "$output_dir/cnc_sim_linuxcnc_source_multiple_spindle_choice_words_error.err"
 # Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc
-# read_one_item() uses the default reader table from interp_array.cc and
-# rejects unknown item-start characters, including middle-of-line N words.
+# read_items() only consumes a leading N word before item dispatch;
+# read_one_item() then uses the default reader table from interp_array.cc
+# and rejects unknown item-start characters, including middle-of-line or
+# comment-prefixed N/O words.
 bad_character_error_cases=(
     "linuxcnc_bad_character_bang_error|Bad character '!' used"
     "linuxcnc_bad_character_middle_n_word_error|Bad character 'n' used"
+    "linuxcnc_comment_prefixed_n_word_error|Bad character 'n' used"
+    "linuxcnc_comment_prefixed_oword_error|Bad character 'o' used"
 )
 for case in "${bad_character_error_cases[@]}"; do
     fixture=${case%%|*}
@@ -881,6 +885,7 @@ oword_reader_error_cases=(
     "linuxcnc_oword_repeat_missing_bracket_error|Left bracket missing after 'repeat'"
     "linuxcnc_oword_too_many_call_parameters_error|Too many subroutine parameters"
     "linuxcnc_m98_missing_p_word_error|Found 'm98' code with no P-word"
+    "linuxcnc_comment_prefixed_m98_error|Unknown m code used: M98"
 )
 for case in "${oword_reader_error_cases[@]}"; do
     fixture=${case%%|*}