Subagent fork sessions persist large JSONL histories indefinitely, causing severe ~/.codex disk bloat

What version of Codex CLI is running?

codex-cli 0.141.0

What subscription do you have?

API

Which model were you using?

gpt-5.5

What platform is your computer?

_No response_

What terminal emulator and version are you using (if applicable)?

_No response_

Codex doctor report

What issue are you seeing?

Codex appears to persist every subagent/fork as a normal local thread rollout under ~/.codex/sessions, including full parent history when the agent is created with full-history fork mode. These JSONL files do not appear to be automatically cleaned up when subagents complete.

On one real install, after multi-agent work:

• ~/.codex/sessions: 54G
• ~/.codex/sessions: 4,468 .jsonl files
• ~/.codex/archived_sessions: 2.0G
• ~/.codex/logs_2.sqlite: 16G
• several individual rollout JSONL files are 400-700 MB
• two parent threads have 548 and 1,797 spawned descendants respectively

This makes local history expensive to scan/load and causes large disk growth over time.

What steps can reproduce the bug?

What steps can reproduce the bug?

1. Start a Codex thread and build up a sizable history.
2. Spawn many subagents using full-history fork behavior, for example legacy fork_context: true or v2 fork_turns: "all" / default full-history behavior.
3. Let the subagents complete.
4. Inspect ~/.codex/sessions.

Useful inspection commands:

du -sh ~/.codex ~/.codex/sessions ~/.codex/archived_sessions ~/.codex/logs_2.sqlite ~/.codex/state_5.sqlite
find ~/.codex/sessions -type f -name '*.jsonl' | wc -l
find ~/.codex/sessions -type f -printf '%s %p\n' | sort -nr | head -20
sqlite3 -readonly ~/.codex/state_5.sqlite \
  "SELECT parent_thread_id, COUNT(*) FROM thread_spawn_edges GROUP BY parent_thread_id ORDER BY COUNT(*) DESC LIMIT 20;"

What is the expected behavior?

Closed subagents become archived/cleaned up.

Additional information

_No response_