Resetting `_runtime_vars` post-(forking-)spawn was
previously only possible via direct mutation of
`_state._runtime_vars` from an external module + an
inline default dict duplicating the
`_state.py`-internal defaults. Split the access
surface into a pure getter + explicit setter so such
a reset call site becomes a one-liner composition:
`set_runtime_vars(get_runtime_vars(clear_values=True))`.
Deats `tractor/runtime/_state.py`,
- extract initial values into a module-level
`_RUNTIME_VARS_DEFAULTS: dict[str, Any]` constant; the
live `_runtime_vars` is now initialised from
`dict(_RUNTIME_VARS_DEFAULTS)`
- `get_runtime_vars()` grows a `clear_values: bool = False`
kwarg. When True, returns a fresh copy of
`_RUNTIME_VARS_DEFAULTS` instead of the live dict —
still a **pure read**, never mutates anything
- new `set_runtime_vars(rtvars: dict | RuntimeVars)` —
atomic replacement of the live dict's contents via
`.clear()` + `.update()`, so existing references to the
same dict object remain valid. Accepts either the
historical dict form or the `RuntimeVars` struct
(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
(cherry picked from commit 7804a9fe57693dd5e15bee6a08e7d2fa14b6a98a)
(factored: kept only the tractor/runtime/_state.py part; dropped
tractor/spawn/_subint_forkserver.py call-site rewire)
Gud Boi
0133bf7074