尽快推进：收紧runtime shim源码锚点

docs/linuxcnc-wasm-shims-source-map.md

@@ -17,7 +17,7 @@ only; it must not add CNC behavior and must not expand the temporary smoke parse
 | `core/wasm_shims/dlfcn.cc` | `src/emc/rs274ngc/interp_base.cc` | Satisfies LinuxCNC `interp_base.cc` dynamic loader calls and RTLD flags for browser-safe probes while keeping dynamic loading unavailable. |
 | `core/wasm_shims/emc_status_shim.cc` | `src/emc/sai/dummyemcstat.cc` | Provides the detached LinuxCNC `EMC_STAT` singleton shape without task/NML startup. |
 | `core/wasm_shims/gettext_shim.cc` | `src/emc/rs274ngc/interp_internal.hh` | Preserves LinuxCNC `_()` diagnostic call sites by satisfying `gettext()` while leaving browser gettext catalogs unavailable. |
-| `core/wasm_shims/linuxcnc_runtime_shim.cc` | `src/emc/rs274ngc/gcodemodule.cc`, `src/emc/task/emctaskmain.cc`, `src/emc/task/taskclass.cc`, `src/emc/rs274ngc/interp_namedparams.cc`, `include/hal.h`, `src/hal/hal_lib.c`, `src/emc/rs274ngc/rs274ngc_pre.cc` | Keeps preview/task, builtin Python module, unavailable HAL lookup, and `wordexp()` edges compile-safe. |
+| `core/wasm_shims/linuxcnc_runtime_shim.cc` | `src/emc/rs274ngc/gcodemodule.cc`, `src/emc/task/emctaskmain.cc`, `src/emc/task/taskclass.cc`, `src/emc/rs274ngc/interp_namedparams.cc`, `include/hal.h`, `src/hal/hal_lib.c`, `src/emc/rs274ngc/rs274ngc_pre.cc` | Keeps preview/task, builtin module stubs, unavailable HAL lookup, and `wordexp()` edges compile-safe. |
 | `core/wasm_shims/nml_status_shim.cc` | `src/libnml/nml/nmlmsg.cc`, `src/libnml/nml/stat_msg.cc` | Provides LinuxCNC NML status constructors, clear behavior, and `RCS_STAT_MSG` default status fields needed by source-linked EMC status objects. |
 | `core/wasm_shims/python_c_api_shim.cc` | `src/emc/rs274ngc/interp_python.cc`, `src/emc/rs274ngc/interp_namedparams.cc`, `src/emc/rs274ngc/gcodemodule.cc`, `src/emc/pythonplugin/python_plugin.cc` | Satisfies Python C API symbols while Python/Boost.Python remap paths remain tracked blockers. |
 | `core/wasm_shims/rcs_print_shim.cc` | `src/libnml/rcs/rcs_print.cc`, `src/libnml/rcs/rcs_print.hh` | Provides the LinuxCNC `rcs_print_error` split entry points used by NML validation without native print routing. |
@@ -36,15 +36,20 @@ only; it must not add CNC behavior and must not expand the temporary smoke parse
 - `core/wasm_shims/emc_status_shim.cc` must stay limited to the detached
   LinuxCNC `EMC_STAT` singleton from `src/emc/sai/dummyemcstat.cc`; it must not
   pull in task startup, NML channels, or operator callback behavior.
-- `core/wasm_shims/linuxcnc_runtime_shim.cc` must keep `_task=0` for preview,
+- `core/wasm_shims/linuxcnc_runtime_shim.cc` must keep preview `_task=0`,
   matching `src/emc/rs274ngc/gcodemodule.cc`; it must not switch browser-safe probes into task mode.
+- The runtime shim's builtin module stubs must match LinuxCNC's
+  `interpreter`/`emccanon` inittab shape from `gcodemodule.cc` and
+  `taskclass.cc` while returning null module pointers; they must not become
+  Python execution.
 - The HAL lookup shim covers `hal_get_pin_value_by_name()`,
   `hal_get_signal_value_by_name()`, and `hal_get_param_value_by_name()` from
   `src/emc/rs274ngc/interp_namedparams.cc`, `include/hal.h`, and
   `src/hal/hal_lib.c`; it must leave HAL values unavailable by returning `-1`,
   `HAL_TYPE_UNINITIALIZED`, and null data pointers.
-- `wordexp()` support is limited to the browser-safe path expansion needed by
-  `src/emc/rs274ngc/rs274ngc_pre.cc`; it must not become a shell expansion feature.
+- `wordexp()` support is limited to the single-word `wordexp()` path expansion
+  and `wordfree()` cleanup needed by `src/emc/rs274ngc/rs274ngc_pre.cc` for
+  basename, program prefix, and subroutine-directory lookups; it must not become a shell expansion feature.
 
 ## Python Shim Boundaries