提示词：

对标 LinuxCNC，分阶段完善 Web 版数控系统仿真的 WASM 程序，继续补齐 G/M 代码语法并严格测试。

总结：
按 LinuxCNC read_g/read_m 的模态组规则，补充同一行同模态组 G/M 码冲突检查；新增 G0 G1 与 M3 M4 拒绝用例。已通过 ./test-native.sh 和 ./test-linuxcnc-source-link.sh。

core/src/smoke_gcode_parser.cpp

@@ -495,6 +495,187 @@ bool has_m_code(const std::vector<Word> &word_list, int code) {
     return false;
 }
 
+int linuxcnc_g_code_number(double value) {
+    const double scaled = value * 10.0;
+    int code = static_cast<int>(std::floor(scaled));
+    const double fraction = scaled - static_cast<double>(code);
+    if (fraction > 0.999) {
+        code = static_cast<int>(std::ceil(scaled));
+    }
+    return code;
+}
+
+int supported_linuxcnc_g_modal_group(double value) {
+    const int code = linuxcnc_g_code_number(value);
+    switch (code) {
+    case 0:
+    case 10:
+    case 20:
+    case 30:
+    case 300:
+    case 500:
+    case 510:
+    case 520:
+    case 610:
+    case 620:
+    case 700:
+    case 710:
+    case 720:
+    case 730:
+    case 740:
+    case 760:
+    case 800:
+    case 810:
+    case 820:
+    case 830:
+    case 840:
+    case 850:
+    case 860:
+    case 870:
+    case 880:
+    case 890:
+        return 1;
+    case 170:
+    case 180:
+    case 190:
+        return 2;
+    case 900:
+    case 910:
+        return 3;
+    case 901:
+    case 911:
+        return 4;
+    case 930:
+    case 940:
+    case 950:
+        return 5;
+    case 200:
+    case 210:
+    case 7000:
+    case 7100:
+        return 6;
+    case 400:
+    case 410:
+    case 411:
+    case 420:
+    case 421:
+        return 7;
+    case 430:
+    case 431:
+    case 432:
+    case 434:
+    case 435:
+    case 490:
+        return 8;
+    case 980:
+    case 990:
+        return 10;
+    case 540:
+    case 550:
+    case 560:
+    case 570:
+    case 580:
+    case 590:
+    case 591:
+    case 592:
+    case 593:
+        return 12;
+    case 611:
+    case 640:
+        return 13;
+    case 960:
+    case 970:
+        return 14;
+    case 70:
+    case 80:
+        return 15;
+    case 922:
+    case 923:
+        return 16;
+    default:
+        return -1;
+    }
+}
+
+int supported_linuxcnc_m_modal_group(int value) {
+    if (value >= 100 && value <= 199) {
+        return 10;
+    }
+    switch (value) {
+    case 0:
+    case 1:
+    case 2:
+    case 30:
+    case 60:
+    case 99:
+        return 4;
+    case 62:
+    case 63:
+    case 64:
+    case 65:
+    case 66:
+        return 5;
+    case 6:
+    case 61:
+        return 6;
+    case 3:
+    case 4:
+    case 5:
+    case 19:
+    case 70:
+    case 71:
+    case 72:
+    case 73:
+        return 7;
+    case 7:
+    case 8:
+    case 9:
+        return 8;
+    case 48:
+    case 49:
+    case 50:
+    case 51:
+    case 52:
+    case 53:
+        return 9;
+    default:
+        return -1;
+    }
+}
+
+bool check_linuxcnc_modal_group_conflicts(const std::vector<Word> &word_list, std::string *error) {
+    std::array<bool, 17> g_modes{};
+    std::array<bool, 11> m_modes{};
+    for (const Word &word : word_list) {
+        if (word.letter == 'G') {
+            const int mode = supported_linuxcnc_g_modal_group(word.value);
+            if (mode < 0) {
+                continue;
+            }
+            if (g_modes[static_cast<size_t>(mode)]) {
+                if (error) {
+                    *error = "Two G codes used from same modal group";
+                }
+                return false;
+            }
+            g_modes[static_cast<size_t>(mode)] = true;
+        } else if (word.letter == 'M') {
+            const int mode = supported_linuxcnc_m_modal_group(rounded_value(word.value));
+            if (mode < 0) {
+                continue;
+            }
+            if (m_modes[static_cast<size_t>(mode)]) {
+                if (error) {
+                    *error = "Two M codes used from same modal group";
+                }
+                return false;
+            }
+            m_modes[static_cast<size_t>(mode)] = true;
+        }
+    }
+    return true;
+}
+
 std::string lower_compact(const std::string &value) {
     std::string out;
     out.reserve(value.size());
@@ -2927,6 +3108,9 @@ int SmokeGcodeParser::parse(const char *program, size_t program_len, std::string
         if (!parse_word_list_strict(line, &word_list, error)) {
             return -1;
         }
+        if (!check_linuxcnc_modal_group_conflicts(word_list, error)) {
+            return -1;
+        }
         refresh_readonly_named_parameters(line_number);
         const std::string o_identifier = first_o_identifier(keyword_line, word_list);
         const bool has_o_word = !o_identifier.empty();

core/tests/cnc_sim_api_smoke.cpp

@@ -3572,6 +3572,25 @@ int main() {
                                        sizeof(duplicate_axis_word_program) - 1) != 0,
                  "expected LinuxCNC to reject multiple X words on one line");
 
+    const char same_modal_group_g_program[] =
+        "G21 G90\n"
+        "F100\n"
+        "G0 G1 X1\n";
+    events.clear();
+    ok &= expect(cnc_sim_parse_program(sim,
+                                       same_modal_group_g_program,
+                                       sizeof(same_modal_group_g_program) - 1) != 0,
+                 "expected LinuxCNC to reject two G codes from the same modal group");
+
+    const char same_modal_group_m_program[] =
+        "G21 G90\n"
+        "M3 M4\n";
+    events.clear();
+    ok &= expect(cnc_sim_parse_program(sim,
+                                       same_modal_group_m_program,
+                                       sizeof(same_modal_group_m_program) - 1) != 0,
+                 "expected LinuxCNC to reject two M codes from the same modal group");
+
     const char scientific_notation_word_program[] =
         "G21 G90\n"
         "F100\n"