Derive remote exec env on the exec-server

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>

codex-rs/exec-server/src/protocol.rs

@@ -2,6 +2,7 @@ use std::collections::HashMap;
 use std::path::PathBuf;
 
 use base64::engine::general_purpose::STANDARD as BASE64_STANDARD;
+use codex_config::types::ShellEnvironmentPolicyInherit;
 use codex_protocol::protocol::SandboxPolicy;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use serde::Deserialize;
@@ -60,11 +61,23 @@ pub struct ExecParams {
     pub process_id: ProcessId,
     pub argv: Vec<String>,
     pub cwd: PathBuf,
+    #[serde(default)]
+    pub env_policy: Option<ExecEnvPolicy>,
     pub env: HashMap<String, String>,
     pub tty: bool,
     pub arg0: Option<String>,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ExecEnvPolicy {
+    pub inherit: ShellEnvironmentPolicyInherit,
+    pub ignore_default_excludes: bool,
+    pub exclude: Vec<String>,
+    pub r#set: HashMap<String, String>,
+    pub include_only: Vec<String>,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct ExecResponse {