Prevent launch context from reaching child processes (#37607)

## Why

Model-reachable child processes should not inherit Codex launch context.

## What changed

- Treat `OPENAI_FEDERATION_RULE_ID` and `OPENAI_IDENTITY_TOKEN_FILE` as non-inheritable environment variables, with case-insensitive matching.
- Remove them after shell environment policy overrides and before spawning commands across execution, MCP, hooks, Git helpers, and remote helper processes.

## Testing

- Cover inherited and explicitly configured variants, including mixed-case names.
- Verify the variables are absent from real child environments and app-server command and process execution.

GitOrigin-RevId: 2535527893985fef0995617f4c5b2462bea7c136

codex-rs/code-mode/Cargo.toml

@@ -16,6 +16,7 @@ workspace = true
 codex-code-mode-protocol = { workspace = true }
 codex-http-client = { workspace = true }
 codex-install-context = { workspace = true }
+codex-protocol = { workspace = true }
 codex-websocket-client = { workspace = true }
 futures = { workspace = true }
 tokio = { workspace = true, features = ["io-util", "macros", "net", "process", "rt", "sync", "time"] }
@@ -24,6 +25,5 @@ tokio-util = { workspace = true, features = ["rt"] }
 tracing = { workspace = true }
 
 [dev-dependencies]
-codex-protocol = { workspace = true }
 pretty_assertions = { workspace = true }
 tokio = { workspace = true, features = ["test-util"] }

codex-rs/code-mode/src/remote_session/connection.rs

@@ -33,6 +33,7 @@ use codex_code_mode_protocol::host::SESSION_RESOURCE_LIMITS_CAPABILITY;
 use codex_code_mode_protocol::host::SupportedProtocolVersions;
 use codex_code_mode_protocol::host::TransportLane;
 use codex_http_client::HttpClientFactory;
+use codex_protocol::shell_environment::scrub_non_inheritable_env_vars;
 use codex_websocket_client::WebSocketConnector;
 use futures::StreamExt;
 use tokio::io::AsyncBufReadExt;
@@ -215,16 +216,16 @@ impl Connection {
         let mut command = Command::new(host_program);
         #[cfg(unix)]
         command.process_group(0);
-        let mut child = command
+        command
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
             .stderr(Stdio::piped())
-            .kill_on_drop(true)
-            .spawn()
-            .map_err(|error| ConnectionError::Spawn {
-                host_program: host_program.to_path_buf(),
-                error,
-            })?;
+            .kill_on_drop(true);
+        scrub_non_inheritable_env_vars(command.as_std_mut());
+        let mut child = command.spawn().map_err(|error| ConnectionError::Spawn {
+            host_program: host_program.to_path_buf(),
+            error,
+        })?;
 
         if let Some(stderr) = child.stderr.take() {
             tokio::spawn(async move {