[codex] Bind shell snapshots to retained thread environments

codex-rs/codex-home/src/instructions/mod.rs

@@ -48,12 +48,6 @@ impl CodexHomeUserInstructionsProvider {
                     continue;
                 }
             };
-            if let Err(err) = std::str::from_utf8(&data) {
-                warnings.push(format!(
-                    "Global AGENTS.md instructions from `{}` contain invalid UTF-8: {err}. Invalid byte sequences were replaced.",
-                    path.display()
-                ));
-            }
             let contents = String::from_utf8_lossy(&data);
             let trimmed = contents.trim();
             if !trimmed.is_empty() {

codex-rs/codex-home/src/instructions/tests.rs

@@ -126,7 +126,7 @@ async fn recoverable_override_read_error_warns_and_falls_back_to_default() {
 }
 
 #[tokio::test]
-async fn invalid_utf8_is_lossy_and_warned() {
+async fn invalid_utf8_is_lossy() {
     let home = TempDir::new().expect("temp dir");
     let path = home.path().join(DEFAULT_AGENTS_MD_FILENAME);
     let mut invalid_utf8 = b"global".to_vec();
@@ -135,18 +135,13 @@ async fn invalid_utf8_is_lossy_and_warned() {
     fs::write(&path, &invalid_utf8).expect("write invalid utf-8");
 
     let outcome = provider(&home).load_user_instructions().await;
-    let utf8_error = std::str::from_utf8(&invalid_utf8).expect_err("invalid utf-8");
-    let warning = format!(
-        "Global AGENTS.md instructions from `{}` contain invalid UTF-8: {utf8_error}. Invalid byte sequences were replaced.",
-        path.display(),
-    );
     assert_eq!(
         outcome,
         expected(
             &home,
             DEFAULT_AGENTS_MD_FILENAME,
             "global\u{fffd} doc",
-            vec![warning]
+            Vec::new()
         )
     );
 }

codex-rs/core/src/agent/control.rs

@@ -6,10 +6,10 @@ use crate::agent::role::resolve_role_config;
 use crate::agent::status::is_final;
 use crate::codex_thread::ThreadConfigSnapshot;
 use crate::config::Config;
+use crate::environment_selection::TurnEnvironmentSnapshot;
 use crate::session::emit_subagent_session_started;
 use crate::session_prefix::format_subagent_context_line;
 use crate::session_prefix::format_subagent_notification_message;
-use crate::shell_snapshot::ShellSnapshot;
 use crate::thread_manager::ResumeThreadWithHistoryOptions;
 use crate::thread_manager::ThreadManagerState;
 use crate::thread_rollout_truncation::truncate_rollout_to_last_n_fork_turns;
@@ -519,11 +519,11 @@ impl AgentControl {
             .ok_or_else(|| CodexErr::UnsupportedOperation("thread manager dropped".to_string()))
     }
 
-    async fn inherited_shell_snapshot_for_source(
+    async fn inherited_environments_for_source(
         &self,
         state: &Arc<ThreadManagerState>,
         session_source: Option<&SessionSource>,
-    ) -> Option<Arc<ShellSnapshot>> {
+    ) -> Option<TurnEnvironmentSnapshot> {
         let Some(SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
             parent_thread_id, ..
         })) = session_source
@@ -532,13 +532,15 @@ impl AgentControl {
         };
 
         let parent_thread = state.get_thread(*parent_thread_id).await.ok()?;
-        let snapshot = parent_thread
-            .codex
-            .session
-            .services
-            .shell_snapshot
-            .load_full()?;
-        (!snapshot.is_failed()).then_some(snapshot)
+        Some(
+            parent_thread
+                .codex
+                .session
+                .services
+                .turn_environments
+                .snapshot()
+                .await,
+        )
     }
 
     async fn inherited_exec_policy_for_source(

codex-rs/core/src/agent/control/residency_tests.rs

@@ -142,7 +142,7 @@ async fn spawn_v2_subagent(
             /*forked_from_thread_id*/ None,
             Some(ThreadSource::Subagent),
             /*metrics_service_name*/ None,
-            /*inherited_shell_snapshot*/ None,
+            /*inherited_environments*/ None,
             /*inherited_exec_policy*/ None,
             /*environments*/ None,
         )

codex-rs/core/src/agent/control/spawn.rs

@@ -4,7 +4,7 @@ use super::*;
 const AGENT_NAMES: &str = include_str!("../agent_names.txt");
 
 struct SpawnAgentThreadInheritance {
-    shell_snapshot: Option<Arc<ShellSnapshot>>,
+    environments: Option<TurnEnvironmentSnapshot>,
     exec_policy: Option<Arc<crate::exec_policy::ExecPolicyManager>>,
 }
 
@@ -156,8 +156,8 @@ impl AgentControl {
         let parent_thread_id = initial_history
             .get_resumed_parent_thread_id()
             .or(stored_parent_thread_id);
-        let inherited_shell_snapshot = self
-            .inherited_shell_snapshot_for_source(&state, Some(&session_source))
+        let inherited_environments = self
+            .inherited_environments_for_source(&state, Some(&session_source))
             .await;
         let inherited_exec_policy = self
             .inherited_exec_policy_for_source(&state, Some(&session_source), &config)
@@ -170,7 +170,7 @@ impl AgentControl {
                 agent_control: self.clone(),
                 session_source,
                 parent_thread_id,
-                inherited_shell_snapshot,
+                inherited_environments,
                 inherited_exec_policy,
             })
             .await
@@ -231,8 +231,8 @@ impl AgentControl {
         };
         let mut reservation = self.state.reserve_spawn_slot(reservation_max_threads)?;
         let inheritance = SpawnAgentThreadInheritance {
-            shell_snapshot: self
-                .inherited_shell_snapshot_for_source(&state, session_source.as_ref())
+            environments: self
+                .inherited_environments_for_source(&state, session_source.as_ref())
                 .await,
             exec_policy: self
                 .inherited_exec_policy_for_source(&state, session_source.as_ref(), &config)
@@ -283,7 +283,7 @@ impl AgentControl {
                     /*forked_from_thread_id*/ None,
                     /*thread_source*/ Some(ThreadSource::Subagent),
                     /*metrics_service_name*/ None,
-                    inheritance.shell_snapshot,
+                    inheritance.environments,
                     inheritance.exec_policy,
                     options.environments.clone(),
                 ))
@@ -386,7 +386,7 @@ impl AgentControl {
         multi_agent_version: MultiAgentVersion,
     ) -> CodexResult<crate::thread_manager::NewThread> {
         let SpawnAgentThreadInheritance {
-            shell_snapshot: inherited_shell_snapshot,
+            environments: inherited_environments,
             exec_policy: inherited_exec_policy,
         } = inheritance;
         if options.fork_parent_spawn_call_id.is_none() {
@@ -513,7 +513,7 @@ impl AgentControl {
                 /*thread_source*/ Some(ThreadSource::Subagent),
                 /*parent_thread_id*/ Some(parent_thread_id),
                 /*forked_from_thread_id*/ Some(parent_thread_id),
-                inherited_shell_snapshot,
+                inherited_environments,
                 inherited_exec_policy,
                 options.environments.clone(),
             )
@@ -665,8 +665,8 @@ impl AgentControl {
             other => (other, AgentMetadata::default()),
         };
         let notification_source = session_source.clone();
-        let inherited_shell_snapshot = self
-            .inherited_shell_snapshot_for_source(&state, Some(&session_source))
+        let inherited_environments = self
+            .inherited_environments_for_source(&state, Some(&session_source))
             .await;
         let inherited_exec_policy = self
             .inherited_exec_policy_for_source(&state, Some(&session_source), &config)
@@ -679,7 +679,7 @@ impl AgentControl {
                 agent_control: self.clone(),
                 session_source,
                 parent_thread_id,
-                inherited_shell_snapshot,
+                inherited_environments,
                 inherited_exec_policy,
             })
             .await?;

codex-rs/core/src/agents_md.rs

@@ -46,7 +46,7 @@ const AGENTS_MD_SEPARATOR: &str = "\n\n--- project-doc ---\n\n";
 /// Loads project AGENTS.md content and combines it with host-provided user
 /// instructions.
 pub(crate) async fn load_project_instructions(
-    config: &mut Config,
+    config: &Config,
     user_instructions: Option<UserInstructions>,
     environments: &TurnEnvironmentSnapshot,
 ) -> Option<LoadedAgentsMd> {
@@ -89,7 +89,7 @@ pub(crate) async fn load_project_instructions(
 /// `Ok(None)`. Unexpected I/O failures bubble up as `Err` so callers can
 /// decide how to handle them.
 async fn read_agents_md(
-    config: &mut Config,
+    config: &Config,
     fs: &dyn ExecutorFileSystem,
     environment_id: &str,
     cwd: &AbsolutePathBuf,
@@ -126,8 +126,6 @@ async fn read_agents_md(
             Err(err) if err.kind() == io::ErrorKind::NotFound => continue,
             Err(err) => return Err(err),
         };
-        warn_invalid_utf8(&p, &data, "Project", &mut config.startup_warnings);
-
         let size = data.len() as u64;
         if size > remaining {
             data.truncate(remaining as usize);
@@ -503,20 +501,6 @@ impl InstructionProvenance {
     }
 }
 
-fn warn_invalid_utf8(
-    path: &AbsolutePathBuf,
-    data: &[u8],
-    source: &str,
-    startup_warnings: &mut Vec<String>,
-) {
-    if let Err(err) = std::str::from_utf8(data) {
-        startup_warnings.push(format!(
-            "{source} AGENTS.md instructions from `{}` contain invalid UTF-8: {err}. Invalid byte sequences were replaced.",
-            path.display()
-        ));
-    }
-}
-
 #[cfg(test)]
 #[path = "agents_md_tests.rs"]
 mod tests;