Honor request PATH in exec-server shell snapshots (#39917)

## What changed

- Apply all per-request environment overrides, including `PATH`, after restoring
  the captured shell environment.
- Remove `runtime_path_prepends` from `ShellSnapshotRequest` and the associated
  PATH replay and deduplication logic.
- Keep the shell snapshot integration test's runtime PATH setup in the command
  being executed.

GitOrigin-RevId: a6f8d2e144bf9977c7434bc58b60ac972f7e0449

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

@@ -269,9 +269,6 @@ pub struct ShellSnapshotRequest {
     pub scope_id: String,
     /// Executor-native shell used to capture and restore the snapshot.
     pub shell: ShellInfo,
-    /// Runtime-owned PATH entries to replay after restoring profile state.
-    #[serde(default, skip_serializing_if = "Vec::is_empty")]
-    pub runtime_path_prepends: Vec<String>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]

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

@@ -132,15 +132,9 @@ impl ShellSnapshotCache {
             return Ok(());
         };
 
-        let restore_snapshot_path = snapshot.environment.contains_key("PATH")
-            && params
-                .env_policy
-                .as_ref()
-                .is_none_or(|policy| !policy.r#set.contains_key("PATH"));
         let request_overrides = params
             .env
             .iter()
-            .filter(|(name, _)| name.as_str() != "PATH" || !restore_snapshot_path)
             .map(|(name, value)| {
                 (
                     name.clone(),
@@ -155,20 +149,6 @@ impl ShellSnapshotCache {
                 .map(|(name, value)| (name.clone(), value.clone())),
         );
         prepared.env.extend(request_overrides);
-        if restore_snapshot_path && let Some(path) = prepared.env.get_mut("PATH") {
-            for entry in &request.runtime_path_prepends {
-                if entry.is_empty() {
-                    continue;
-                }
-                *path = std::iter::once(entry.as_str())
-                    .chain(
-                        path.split(':')
-                            .filter(|existing| !existing.is_empty() && *existing != entry),
-                    )
-                    .collect::<Vec<_>>()
-                    .join(":");
-            }
-        }
         prepared
             .env
             .retain(|name, _| !shell_environment::is_non_inheritable_env_var(name));

codex-rs/exec-server/tests/exec_process.rs

@@ -141,8 +141,6 @@ async fn shell_snapshot_v2_filters_profile_exports_and_stays_in_memory(
     let profile_path = home.path().join(profile_name);
     let profile_path_entry = home.path().join("profile-bin");
     let runtime_path_entry = home.path().join("runtime-bin");
-    let inherited_path = std::env::var("PATH")?;
-    let runtime_path = format!("{}:{inherited_path}", runtime_path_entry.display());
     let padding = if !use_remote && !tty && shell_name == "bash" {
         format!(
             "snapshot_padding() {{ printf '%s' '{}'; }}\n",
@@ -190,7 +188,8 @@ async fn shell_snapshot_v2_filters_profile_exports_and_stays_in_memory(
         ("profile_helper; ", "helper")
     };
     let command = format!(
-        "{command_prefix}printf '|%s|%s|%s|%s|%s|%s' \"$PROFILE_ALLOWED\" \"${{PROFILE_SECRET-missing}}\" \"${{PROFILE_DENIED-missing}}\" \"$PATH\" \"${{__CODEX_SHELL_SNAPSHOT_STATE_0-missing}}\" \"${{__CODEX_SHELL_SNAPSHOT_STATE_1-missing}}\""
+        "export PATH='{}':\"$PATH\"; {command_prefix}printf '|%s|%s|%s|%s|%s|%s' \"$PROFILE_ALLOWED\" \"${{PROFILE_SECRET-missing}}\" \"${{PROFILE_DENIED-missing}}\" \"$PATH\" \"${{__CODEX_SHELL_SNAPSHOT_STATE_0-missing}}\" \"${{__CODEX_SHELL_SNAPSHOT_STATE_1-missing}}\"",
+        runtime_path_entry.display(),
     );
     let expected_stdout = format!(
         "{expected_prefix}|profile|missing|missing|{}:{}:/usr/bin:/bin|missing|missing",
@@ -212,9 +211,8 @@ async fn shell_snapshot_v2_filters_profile_exports_and_stays_in_memory(
                         name: shell_name.to_string(),
                         path: shell_path.to_string(),
                     },
-                    runtime_path_prepends: vec![runtime_path_entry.to_string_lossy().into_owned()],
                 }),
-                env: HashMap::from([("PATH".to_string(), runtime_path.clone())]),
+                env: HashMap::new(),
                 tty,
                 pipe_stdin: false,
                 arg0: None,
@@ -293,7 +291,6 @@ async fn shell_snapshot_v2_remote_managed_proxy_uses_prepared_execution_context(
                         name: "bash".to_string(),
                         path: "/bin/bash".to_string(),
                     },
-                    runtime_path_prepends: Vec::new(),
                 }),
                 env: HashMap::new(),
                 tty: false,
@@ -362,7 +359,6 @@ async fn shell_snapshot_v2_capture_failure_falls_back_to_original_command() -> R
                 name: "bash".to_string(),
                 path: "/bin/bash".to_string(),
             },
-            runtime_path_prepends: Vec::new(),
         }),
         env: HashMap::new(),
         tty: false,