Patch Changes
- f0aa52d: Adopt the loaded session agent spec when resuming chat history so New Chat draft edits no longer PATCH over the saved sandbox environment; lock composer environment selection after a session exists; read/write sandbox
environmentNameso resumed chats show the correct environment; and keep showing a deleted environment from the agent spec. - bbe23c8: Surface cancelled turn reasons and failed sub-agents on the Agent Sessions timeline and metrics; project unfinished nested sub-agents as cancelled when the parent turn is already terminal, remap abort-shaped child thread.done errors (e.g. LLM stream aborted) to cancelled on cancelled turns, and close unfinished sub-agent chart bars at turn.done when thread.done is missing.