Two new steps per language: function returning nothing and function
returning explicit nil/None. Both tagged $(test)_PASS — they would
have failed before the lua nil fix (Lua side reported nil result as
error). Python side already worked but is covered for parity.
- py_func and lua_func items accept a context_id parameter; items sharing
the same id reuse the same subprocess for the duration of the test run
- Subprocess-side tm.setgd/tm.gd use a local fallback dict for non-JSON-
serializable values (py_func only); serializable values reach the main
process global dict and are accessible from any test item or subprocess
- Shared subprocess engines are cleaned up in process.py finally block
- LuaProcessBase gains is_alive() (was missing, broke all lua_func items)
- Validation tests cover serializable sharing across different context ids,
non-serializable sharing within the same context_id, and cross-item access
- RST documentation updated for both py_func and lua_func items
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
