Four surfaces build a throwaway AIAgent and never call close() — the
owner boundary that releases memory-provider sessions, tool
subprocesses and httpx clients. In long-lived processes each run leaked
all of them until exit:
- batch_runner._process_single_prompt: one agent per prompt, N prompts
per batch process.
- feishu_comment._run_comment_agent: one agent per comment run in the
gateway process.
- tui_gateway prompt.background: one side agent per background turn.
- cli /bg: one agent per background task in the CLI process.
Wrap each run in try/finally with a suppressed close(), mirroring
gateway/run.py's owner pattern. preview.restart stays deliberately
unclosed (its task exists to leave a detached server running), and the
prompt.background side agent is safe to close: its session_id is the bg
task id, so close() reaps only its own task resources.
Fixes#50197
94f3dbec9b