继续按 align-linuxcnc 约束：补块读取 native 覆盖，测试通过

结论：补齐 LinuxCNC interp_read.cc read_items()/read_one_item() 坏字符路径，以及 interp_check.cc check_m_codes() M 码数量错误的 native 校验；./test-native.sh 与 ./test-linuxcnc-source-link.sh 均通过，未扩展 smoke。

docs/linuxcnc-porting.md

@@ -217,6 +217,6 @@ This matrix tracks LinuxCNC feature coverage for the web/WASM simulator. A featu
 | Parameter expressions and operators | covered for parameter references, native/source `mod`, `**`, logical, and relational operator precedence, plus LinuxCNC parameter-setting syntax, parameter index validation, named-parameter termination, real-number parsing, divide-by-zero, negative sqrt/power, infinity rejection, malformed and bare `ATAN[]/[]`, unary operation syntax including bare unary items, `read_operation_unary()` unknown-word branches, `read_operation()` binary-operation prefix, unknown operation, and unclosed-expression error paths from `interp_read.cc`/`interp_execute.cc` | `tests/gcode/linuxcnc_parameter_expression_assignment.ngc`, `tests/gcode/linuxcnc_parameter_missing_equal_error.ngc`, `tests/gcode/linuxcnc_midline_parameter_missing_equal_error.ngc`, `tests/gcode/linuxcnc_parameter_missing_value_error.ngc`, `tests/gcode/linuxcnc_parameter_number_out_of_range_error.ngc`, `tests/gcode/linuxcnc_parameter_reference_out_of_range_error.ngc`, `tests/gcode/linuxcnc_non_integer_parameter_index_error.ngc`, `tests/gcode/linuxcnc_named_parameter_not_terminated_error.ngc`, `tests/gcode/linuxcnc_no_real_value_error.ngc`, `tests/gcode/linuxcnc_bad_number_format_error.ngc`, `tests/gcode/linuxcnc_expression_operators.ngc`, `tests/gcode/linuxcnc_negative_sqrt_error.ngc`, `tests/gcode/linuxcnc_divide_by_zero_error.ngc`, `tests/gcode/linuxcnc_negative_power_error.ngc`, `tests/gcode/linuxcnc_infinite_expression_error.ngc`, `tests/gcode/linuxcnc_atan_missing_slash_error.ngc`, `tests/gcode/linuxcnc_atan_missing_bracket_error.ngc`, `tests/gcode/linuxcnc_top_level_bare_atan_error.ngc`, `tests/gcode/linuxcnc_midline_bare_atan_error.ngc`, `tests/gcode/linuxcnc_unary_missing_bracket_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_c_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_e_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_f_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_l_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_r_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_s_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_t_word_error.ngc`, `tests/gcode/linuxcnc_unary_unknown_default_word_error.ngc`, `tests/gcode/linuxcnc_top_level_bare_unary_error.ngc`, `tests/gcode/linuxcnc_midline_bare_unary_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_a_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_e_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_g_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_l_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_m_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_n_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_o_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_x_operation_error.ngc`, `tests/gcode/linuxcnc_binary_unknown_operation_error.ngc`, `tests/gcode/linuxcnc_unclosed_expression_error.ngc` |
 | Word reader validation | LinuxCNC native/source reader errors covered for negative `F/G/H/L/M/S/T` values and repeated `A/B/C/D/E/F/H/I/J/K/L/P/Q/R/S/T/U/V/W/X/Y/Z` words from `interp_read.cc` | `tests/gcode/linuxcnc_negative_f_word_error.ngc`, `tests/gcode/linuxcnc_negative_g_code_error.ngc`, `tests/gcode/linuxcnc_negative_h_word_error.ngc`, `tests/gcode/linuxcnc_negative_l_word_error.ngc`, `tests/gcode/linuxcnc_negative_m_code_error.ngc`, `tests/gcode/linuxcnc_negative_s_word_error.ngc`, `tests/gcode/linuxcnc_negative_t_word_error.ngc`, `tests/gcode/linuxcnc_multiple_a_words_error.ngc`, `tests/gcode/linuxcnc_multiple_b_words_error.ngc`, `tests/gcode/linuxcnc_multiple_c_words_error.ngc`, `tests/gcode/linuxcnc_multiple_d_words_error.ngc`, `tests/gcode/linuxcnc_multiple_e_words_error.ngc`, `tests/gcode/linuxcnc_multiple_f_words_error.ngc`, `tests/gcode/linuxcnc_multiple_h_words_error.ngc`, `tests/gcode/linuxcnc_multiple_i_words_error.ngc`, `tests/gcode/linuxcnc_multiple_j_words_error.ngc`, `tests/gcode/linuxcnc_multiple_k_words_error.ngc`, `tests/gcode/linuxcnc_multiple_l_words_error.ngc`, `tests/gcode/linuxcnc_multiple_p_words_error.ngc`, `tests/gcode/linuxcnc_multiple_q_words_error.ngc`, `tests/gcode/linuxcnc_multiple_r_words_error.ngc`, `tests/gcode/linuxcnc_multiple_s_words_error.ngc`, `tests/gcode/linuxcnc_multiple_t_words_error.ngc`, `tests/gcode/linuxcnc_multiple_u_words_error.ngc`, `tests/gcode/linuxcnc_multiple_v_words_error.ngc`, `tests/gcode/linuxcnc_multiple_w_words_error.ngc`, `tests/gcode/linuxcnc_multiple_x_words_error.ngc`, `tests/gcode/linuxcnc_multiple_y_words_error.ngc`, `tests/gcode/linuxcnc_multiple_z_words_error.ngc` |
 | G/M reader validation | LinuxCNC native/source `read_g()`/`read_m()` errors covered for range checks, unknown code tables, and same-modal-group conflicts from `interp_read.cc` and `interp_array.cc` | `tests/gcode/linuxcnc_g_code_out_of_range_error.ngc`, `tests/gcode/linuxcnc_unknown_g_code_error.ngc`, `tests/gcode/linuxcnc_two_g_codes_same_modal_group_error.ngc`, `tests/gcode/linuxcnc_m_code_greater_199_error.ngc`, `tests/gcode/linuxcnc_unknown_m_code_error.ngc`, `tests/gcode/linuxcnc_two_m_codes_same_modal_group_error.ngc` |
-| Block/item reader validation | LinuxCNC native/source errors covered for repeated `$` and unused `D/$/E/H/I/J/K/L/P/Q/R` words; source-linked coverage also checks bad item-start characters, middle-of-line or comment-prefixed `N` words, comment-prefixed or midline `O` words, top-level or midline bracket items, naked top-level numbers, malformed leading `N` numbers, EOF/program-end file checks, overlong file lines, and too many M-codes from `interp_read.cc`, `interp_array.cc`, and `interp_check.cc` | `tests/gcode/linuxcnc_multiple_spindle_choice_words_error.ngc`, `tests/gcode/linuxcnc_d_word_no_use_error.ngc`, `tests/gcode/linuxcnc_spindle_dollar_no_use_error.ngc`, `tests/gcode/linuxcnc_e_word_no_use_error.ngc`, `tests/gcode/linuxcnc_h_word_no_use_error.ngc`, `tests/gcode/linuxcnc_i_word_no_use_error.ngc`, `tests/gcode/linuxcnc_j_word_no_use_error.ngc`, `tests/gcode/linuxcnc_k_word_no_use_error.ngc`, `tests/gcode/linuxcnc_l_word_no_use_error.ngc`, `tests/gcode/linuxcnc_p_word_no_use_error.ngc`, `tests/gcode/linuxcnc_q_word_no_use_error.ngc`, `tests/gcode/linuxcnc_r_word_no_use_error.ngc`, `tests/gcode/linuxcnc_bad_character_bang_error.ngc`, `tests/gcode/linuxcnc_bad_character_middle_n_word_error.ngc`, `tests/gcode/linuxcnc_comment_prefixed_n_word_error.ngc`, `tests/gcode/linuxcnc_comment_prefixed_spaced_n_word_error.ngc`, `tests/gcode/linuxcnc_comment_prefixed_oword_error.ngc`, `tests/gcode/linuxcnc_midline_numeric_oword_error.ngc`, `tests/gcode/linuxcnc_midline_named_oword_error.ngc`, `tests/gcode/linuxcnc_bad_character_top_left_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_top_right_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_midline_left_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_midline_right_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_top_number_error.ngc`, `tests/gcode/linuxcnc_bad_n_number_format_error.ngc`, `tests/gcode/linuxcnc_file_ended_no_program_end_error.ngc`, `tests/gcode/linuxcnc_file_ended_no_percent_error.ngc`, generated `linuxcnc_command_too_long_error.ngc`, `tests/gcode/linuxcnc_too_many_m_codes_error.ngc` |
+| Block/item reader validation | LinuxCNC native/source errors covered for repeated `$`, unused `D/$/E/H/I/J/K/L/P/Q/R` words, bad item-start characters, middle-of-line or comment-prefixed `N` words, comment-prefixed or midline `O` words, top-level or midline bracket items, naked top-level numbers, non-leading ATAN argument slashes, and too many M-codes from `interp_read.cc`, `interp_array.cc`, and `interp_check.cc`; source-linked coverage also checks malformed leading `N` numbers, EOF/program-end file checks, and overlong file lines | `tests/gcode/linuxcnc_multiple_spindle_choice_words_error.ngc`, `tests/gcode/linuxcnc_d_word_no_use_error.ngc`, `tests/gcode/linuxcnc_spindle_dollar_no_use_error.ngc`, `tests/gcode/linuxcnc_e_word_no_use_error.ngc`, `tests/gcode/linuxcnc_h_word_no_use_error.ngc`, `tests/gcode/linuxcnc_i_word_no_use_error.ngc`, `tests/gcode/linuxcnc_j_word_no_use_error.ngc`, `tests/gcode/linuxcnc_k_word_no_use_error.ngc`, `tests/gcode/linuxcnc_l_word_no_use_error.ngc`, `tests/gcode/linuxcnc_p_word_no_use_error.ngc`, `tests/gcode/linuxcnc_q_word_no_use_error.ngc`, `tests/gcode/linuxcnc_r_word_no_use_error.ngc`, `tests/gcode/linuxcnc_bad_character_bang_error.ngc`, `tests/gcode/linuxcnc_bad_character_middle_n_word_error.ngc`, `tests/gcode/linuxcnc_comment_prefixed_n_word_error.ngc`, `tests/gcode/linuxcnc_comment_prefixed_spaced_n_word_error.ngc`, `tests/gcode/linuxcnc_comment_prefixed_oword_error.ngc`, `tests/gcode/linuxcnc_midline_numeric_oword_error.ngc`, `tests/gcode/linuxcnc_midline_named_oword_error.ngc`, `tests/gcode/linuxcnc_bad_character_top_left_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_top_right_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_midline_left_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_midline_right_bracket_error.ngc`, `tests/gcode/linuxcnc_bad_character_top_number_error.ngc`, `tests/gcode/linuxcnc_top_level_bare_atan_error.ngc`, `tests/gcode/linuxcnc_midline_bare_atan_error.ngc`, `tests/gcode/linuxcnc_bad_n_number_format_error.ngc`, `tests/gcode/linuxcnc_file_ended_no_program_end_error.ngc`, `tests/gcode/linuxcnc_file_ended_no_percent_error.ngc`, generated `linuxcnc_command_too_long_error.ngc`, `tests/gcode/linuxcnc_too_many_m_codes_error.ngc` |
 | Broader canned cycles `G73`, `G74`, `G82`-`G89` | partially covered: `G73`, `G74`, `G82`, `G83`, `G84`, `G85`, `G86`, `G87`, `G88`, `G89`; smoke parser maps supported cycles across `G17/G18/G19`, including LinuxCNC's special non-XY `G74/G84` tapping argument order and `G87` plane-specific `I/J/K` mapping; native/source regressions now check non-XY `G74/G84/G86/G87/G88` sequences | `tests/gcode/linuxcnc_canned_cycles_extended.ngc`, `tests/gcode/linuxcnc_canned_cycle_planes.ngc`, smoke API regression |
 | Full source-level wasm build | covered for the current wasm-safe RS274 source set, with remaining work focused on broadening browser-hostile dependency replacement and feature coverage | `./build-wasm.sh`, `test-linuxcnc-wasm-runtime-link.sh`, `test-web-wasm-node-smoke.sh`, `test-web-wasm-browser-smoke.sh` |

test-linuxcnc-rs274-native.sh

@@ -250,6 +250,49 @@ for case in "${gm_reader_error_cases[@]}"; do
     grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_$fixture.err"
 done
 # Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc
+# 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, midline O-words, bracket expressions, naked
+# numbers, and non-leading ATAN argument slashes.
+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_spaced_n_word_error|Bad character 'n' used"
+    "linuxcnc_comment_prefixed_oword_error|Bad character 'o' used"
+    "linuxcnc_midline_numeric_oword_error|Bad character 'o' used"
+    "linuxcnc_midline_named_oword_error|Bad character 'o' used"
+    "linuxcnc_bad_character_top_left_bracket_error|Bad character '[' used"
+    "linuxcnc_bad_character_top_right_bracket_error|Bad character ']' used"
+    "linuxcnc_bad_character_midline_left_bracket_error|Bad character '[' used"
+    "linuxcnc_bad_character_midline_right_bracket_error|Bad character ']' used"
+    "linuxcnc_bad_character_top_number_error|Bad character '1' used"
+    "linuxcnc_top_level_bare_atan_error|Bad character '/' used"
+    "linuxcnc_midline_bare_atan_error|Bad character '/' used"
+)
+for case in "${bad_character_error_cases[@]}"; do
+    fixture=${case%%|*}
+    expected=${case#*|}
+    if CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" \
+        "$build_dir/linuxcnc_rs274_dump" "tests/gcode/$fixture.ngc" \
+        >"$output_dir/cnc_sim_linuxcnc_$fixture.json" 2>"$output_dir/cnc_sim_linuxcnc_$fixture.err"; then
+        echo "expected $fixture.ngc to fail" >&2
+        exit 1
+    fi
+    grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_$fixture.err"
+done
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_check.cc
+# check_m_codes() rejects blocks with more than MAX_EMS M-codes.
+if CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" \
+    "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_too_many_m_codes_error.ngc \
+    >"$output_dir/cnc_sim_linuxcnc_too_many_m_codes_error.json" 2>"$output_dir/cnc_sim_linuxcnc_too_many_m_codes_error.err"; then
+    echo "expected linuxcnc_too_many_m_codes_error.ngc to fail" >&2
+    exit 1
+fi
+grep -Fq "Too many m codes on line" \
+    "$output_dir/cnc_sim_linuxcnc_too_many_m_codes_error.err"
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc
 # read_f()/read_g()/read_h()/read_l()/read_m()/read_s()/read_t()
 # reject negative word values before command execution.
 negative_word_error_cases=(