Add an exec-server env policy contract and send only the env overlay needed for runtime/sandbox transforms when Core starts remote unified-exec processes. Keep local process startup on the existing exact-env path, and share the shell-environment-policy builder from codex-config so the executor can apply the same inherit/filter/set/include rules against its own process environment.
Co-authored-by: Codex <noreply@openai.com>
Stacked PR 2/3, based on the stub PR.
Adds the exec RPC implementation and process/event flow in exec-server
only.
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Co-authored-by: Codex <noreply@openai.com>