Add thread section management APIs (#36380)

## What changed

- Add `threadSection/create`, `threadSection/update`, and `threadSection/delete` app-server methods, with generated protocol schemas and TypeScript bindings.
- Persist custom sections in SQLite with stable UUIDv7 identities, trim and validate display names, and prevent renaming or deleting the built-in pinned section.
- Delete sections transactionally and return their active and archived threads to the unsectioned list.
- Serialize section mutations with section listing so concurrent requests observe ordered updates.

## Testing

- Cover section persistence across restarts, ordered renames, member cleanup on deletion, invalid requests, unsupported stores, and thread-store/state-runtime behavior.

GitOrigin-RevId: dc9a4be283c21dbc93ab1829eafc4825d8df6575

codex-rs/thread-store/src/local/mod.rs

@@ -14,6 +14,7 @@ mod rollout_lineage;
 mod search_threads;
 mod thread_history;
 mod thread_history_materialization;
+mod thread_sections;
 mod unarchive_thread;
 mod update_thread_metadata;
 mod writer_lock;
@@ -41,10 +42,13 @@ use crate::AppendThreadItemsParams;
 use crate::ArchiveThreadParams;
 use crate::ArchiveThreadsParams;
 use crate::CreateThreadParams;
+use crate::CreateThreadSectionParams;
 use crate::DeleteThreadParams;
+use crate::DeleteThreadSectionParams;
 use crate::DeleteThreadsParams;
 use crate::ItemPage;
 use crate::ListItemsParams;
+use crate::ListThreadSectionsParams;
 use crate::ListThreadsParams;
 use crate::ListTurnsParams;
 use crate::LoadThreadHistoryParams;
@@ -53,12 +57,15 @@ use crate::PrepareForkParams;
 use crate::PreparedFork;
 use crate::ReadThreadByRolloutPathParams;
 use crate::ReadThreadParams;
+use crate::RenameThreadSectionParams;
 use crate::ResumeThreadParams;
 use crate::SearchThreadOccurrencesParams;
 use crate::SearchThreadsParams;
 use crate::StoredModelContext;
 use crate::StoredThread;
 use crate::StoredThreadHistory;
+use crate::StoredThreadSection;
+use crate::StoredThreadSectionsPage;
 use crate::ThreadOccurrenceSearchPage;
 use crate::ThreadPage;
 use crate::ThreadSearchPage;
@@ -458,6 +465,38 @@ impl ThreadStore for LocalThreadStore {
         Box::pin(async move { list_threads::list_threads(self, params).await })
     }
 
+    fn supports_thread_sections(&self) -> bool {
+        self.state_db.is_some()
+    }
+
+    fn list_thread_sections(
+        &self,
+        params: ListThreadSectionsParams,
+    ) -> ThreadStoreFuture<'_, StoredThreadSectionsPage> {
+        Box::pin(async move { thread_sections::list_thread_sections(self, params).await })
+    }
+
+    fn create_thread_section(
+        &self,
+        params: CreateThreadSectionParams,
+    ) -> ThreadStoreFuture<'_, StoredThreadSection> {
+        Box::pin(async move { thread_sections::create_thread_section(self, params).await })
+    }
+
+    fn rename_thread_section(
+        &self,
+        params: RenameThreadSectionParams,
+    ) -> ThreadStoreFuture<'_, Option<StoredThreadSection>> {
+        Box::pin(async move { thread_sections::rename_thread_section(self, params).await })
+    }
+
+    fn delete_thread_section(
+        &self,
+        params: DeleteThreadSectionParams,
+    ) -> ThreadStoreFuture<'_, bool> {
+        Box::pin(async move { thread_sections::delete_thread_section(self, params).await })
+    }
+
     fn supports_paginated_history_lists(&self) -> bool {
         self.state_db.is_some()
     }