fix(code-runtime): separate model environment from native startup paths

packages/code-runtime/code-runtime-node/README.md

@@ -83,7 +83,7 @@ The host owns policy, deadlines, binding lookup and process cleanup. The child o
 
 ### Launch and control
 
-The host strips erasable types, resolves the executable and bootstrap in the configured execution world, wraps the argv through `ctx.sandbox`, and spawns through `ctx.subprocess`. Native launchers retain executable-search and Windows system paths during startup. The child adopts the inherited control channel and clears every environment entry before evaluating the program. Explicit Node arguments avoid inheriting host loader or inspector flags.
+The host strips erasable types, resolves the executable and bootstrap in the configured execution world, wraps the argv through `ctx.sandbox`, and spawns through `ctx.subprocess`. After adopting the inherited control channel, the child retains only executable-search and Windows system paths in its OS environment and replaces the program-visible `process.env` with an empty dictionary. The retained native paths keep nested Windows process creation functional. Explicit Node arguments avoid inheriting host loader or inspector flags.
 
 Length-framed JSON travels separately from stdout/stderr. The host bounds frames and queued writes, validates call identity and declared binding names before dispatch, and refuses invalid traffic. Output capture meters serialized logs plus the completion or diagnostic; fixed result-envelope fields and sandbox metadata are outside that ledger.