feat: move extension scope ids into ExtensionData (#22490)

## Summary
- add a scoped level_id to ExtensionData and expose it through
level_id()
- remove thread_id/turn_id parameters from extension contributor inputs
where the scoped ExtensionData already carries that identity
- move turn-scoped extension data onto TurnContext so token usage and
lifecycle contributors can share the same turn store

## Testing
- cargo check -p codex-extension-api -p codex-core --tests
- cargo test -p codex-extension-api
- cargo test -p codex-guardian
- cargo test -p codex-core --lib
record_token_usage_info_notifies_extension_contributors
- cargo test -p codex-core --lib
submission_loop_channel_close_emits_thread_stop_lifecycle
- cargo test -p codex-core --lib
submission_loop_channel_close_aborts_active_turn_before_thread_stop_lifecycle
- just fix -p codex-extension-api
- just fix -p codex-guardian
- just fix -p codex-core
- just fmt

## Note
- Attempted cargo test -p codex-core; it aborted in
agent::control::tests::spawn_agent_fork_last_n_turns_keeps_only_recent_turns
with the existing stack overflow before the full suite completed.

codex-rs/ext/extension-api/examples/enabled_extensions.rs

@@ -13,9 +13,9 @@ fn main() {
     let registry = builder.build();
 
     // 2. The host decides which stores are shared.
-    let session_store = ExtensionData::new();
-    let first_thread_store = ExtensionData::new();
-    let second_thread_store = ExtensionData::new();
+    let session_store = ExtensionData::new("session");
+    let first_thread_store = ExtensionData::new("thread-1");
+    let second_thread_store = ExtensionData::new("thread-2");
 
     // 3. Reusing the same session store shares session state across threads.
     let first_thread_fragments = contribute_prompt(&registry, &session_store, &first_thread_store);

codex-rs/ext/extension-api/src/contributors.rs

@@ -1,7 +1,6 @@
 use std::future::Future;
 use std::sync::Arc;
 
-use codex_protocol::ThreadId;
 use codex_protocol::items::TurnItem;
 use codex_protocol::protocol::ReviewDecision;
 use codex_protocol::protocol::TokenUsageInfo;
@@ -79,8 +78,7 @@ pub trait TokenUsageContributor: Send + Sync {
         &self,
         _session_store: &ExtensionData,
         _thread_store: &ExtensionData,
-        _thread_id: ThreadId,
-        _turn_id: &str,
+        _turn_store: &ExtensionData,
         _token_usage: &TokenUsageInfo,
     ) {
     }

codex-rs/ext/extension-api/src/contributors/thread_lifecycle.rs

@@ -1,11 +1,7 @@
-use codex_protocol::ThreadId;
-
 use crate::ExtensionData;
 
 /// Input supplied when the host starts a runtime for a thread.
 pub struct ThreadStartInput<'a, C> {
-    /// Identifier for the thread whose runtime is starting.
-    pub thread_id: ThreadId,
     /// Host configuration visible at thread start.
     pub config: &'a C,
     /// Store scoped to the host session runtime.
@@ -16,8 +12,6 @@ pub struct ThreadStartInput<'a, C> {
 
 /// Input supplied when the host resumes an existing thread.
 pub struct ThreadResumeInput<'a> {
-    /// Identifier for the thread being resumed.
-    pub thread_id: ThreadId,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.
@@ -26,8 +20,6 @@ pub struct ThreadResumeInput<'a> {
 
 /// Input supplied when the host stops a thread runtime.
 pub struct ThreadStopInput<'a> {
-    /// Identifier for the thread whose runtime is stopping.
-    pub thread_id: ThreadId,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.

codex-rs/ext/extension-api/src/contributors/turn_lifecycle.rs

@@ -1,14 +1,9 @@
-use codex_protocol::ThreadId;
 use codex_protocol::protocol::TurnAbortReason;
 
 use crate::ExtensionData;
 
 /// Input supplied when the host starts a turn.
 pub struct TurnStartInput<'a> {
-    /// Identifier for the thread containing this turn.
-    pub thread_id: ThreadId,
-    /// Identifier for the turn that is starting.
-    pub turn_id: &'a str,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.
@@ -19,10 +14,6 @@ pub struct TurnStartInput<'a> {
 
 /// Input supplied when the host completes a turn.
 pub struct TurnStopInput<'a> {
-    /// Identifier for the thread containing this turn.
-    pub thread_id: ThreadId,
-    /// Identifier for the turn that is stopping.
-    pub turn_id: &'a str,
     /// Store scoped to the host session runtime.
     pub session_store: &'a ExtensionData,
     /// Store scoped to this thread runtime.
@@ -33,10 +24,6 @@ pub struct TurnStopInput<'a> {
 
 /// Input supplied when the host aborts a turn.
 pub struct TurnAbortInput<'a> {
-    /// Identifier for the thread containing this turn.
-    pub thread_id: ThreadId,
-    /// Identifier for the turn that is aborting.
-    pub turn_id: &'a str,
     /// Reason the host aborted the turn.
     pub reason: TurnAbortReason,
     /// Store scoped to the host session runtime.

codex-rs/ext/extension-api/src/state.rs

@@ -8,15 +8,24 @@ use std::sync::PoisonError;
 type ErasedData = Arc<dyn Any + Send + Sync>;
 
 /// Typed extension-owned data attached to one host object.
-#[derive(Default, Debug)]
+#[derive(Debug)]
 pub struct ExtensionData {
+    level_id: String,
     entries: Mutex<HashMap<TypeId, ErasedData>>,
 }
 
 impl ExtensionData {
-    /// Creates an empty attachment map.
-    pub fn new() -> Self {
-        Self::default()
+    /// Creates an empty attachment map for one host-owned scope.
+    pub fn new(level_id: impl Into<String>) -> Self {
+        Self {
+            level_id: level_id.into(),
+            entries: Mutex::new(HashMap::new()),
+        }
+    }
+
+    /// Returns the host identity for the scope this data is attached to.
+    pub fn level_id(&self) -> &str {
+        &self.level_id
     }
 
     /// Returns the attached value of type `T`, if one exists.