Codex CLI runs out of context instead of compacting/resuming long thread with many tool calls

What version of Codex CLI is running?

codex-cli 0.125.0

What subscription do you have?

Pro

Which model were you using?

gpt-5.5 xhigh

What platform is your computer?

Darwin 24.6.0 x86_64 i386

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

Ghostty 1.3.1

What issue are you seeing?

During a long Codex CLI session, Codex hit the context-window limit and showed this message:

Codex ran out of room in the model's context window. Start a new thread or clear earlier
history before retrying.

The session was not able to continue normally from the existing thread. I had to start/use a new compacted context instead of the CLI automatically compacting the conversation or giving a working continuation path.

Uploaded thread:

019dd000-1909-7592-9fa5-c26c1f006225

What steps can reproduce the bug?

1. Start a Codex CLI session using codex-cli 0.125.0.
2. Ask Codex to do a research-heavy task that requires current web/GitHub investigation.
3. In my thread, the task was researching Xiaomi S20+ vacuum map backup/recovery. The turn included:

• 30 built-in web tool actions: 8 searches, 20 page opens, and 2 find-in-page operations.
• 58 shell tool interactions: 53 exec_command calls and 5 write_stdin calls.
• All 53 exec_command calls were curl-backed shell commands, covering GitHub raw files, GitHub API endpoints, Xiaomi MIOT spec endpoints, and related project documentation.

1. Several tool outputs were large. The largest recorded tool output was:

curl -sL
'https://raw.githubusercontent.com/Tasshack/dreame-vacuum/master/custom_components/dreame_vacuum/dreame/resources.py'
Original token count: 815104
Output bytes in transcript: 40167

1. Before the error, the session token logs showed cumulative token usage growing well beyond the model context window. The final token-count event immediately before the failure was:

total_tokens: 258400
model_context_window: 258400

1. Codex then failed before producing the final answer with:

Codex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying.

Uploaded thread: 019dd000-1909-7592-9fa5-c26c1f006225

What is the expected behavior?

Codex CLI should compact the conversation automatically instead of requiring the user to start a new thread or manually clear earlier history.

Additional information

_No response_