1m context window gone after Gpt 5.5 Release.

[Zakisb]

What version of the Codex App are you using (From “About Codex” dialog)?

26.422.20832

What subscription do you have?

Pro plan

What platform is your computer?

Mac os

What issue are you seeing?

I've enable 1m context window via codex config since the release of GPT 5.4 and it was working exceptionally well. today Codex announces GPT 5.5 stating it supports 1m Context window but weirdly thought it's gone in the codex app.

What steps can reproduce the bug?

Just launch the codex app and enable 1m context window in config.toml file

What is the expected behavior?

Having 1m context window automatically enabled

Additional information

here's my current config.toml file

model = "gpt-5.5"
model_reasoning_effort = "xhigh"
model_context_window = 1000000
model_auto_compact_token_limit = 900000
personality = "pragmatic"

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• config.toml context window settings are not respected #19185
• Codex Pro GPT-5.4 long context regressed: ~672k worked Apr 22, ~290k fails Apr 23 #19142
• Codex CLI freezes near auto-compaction threshold and drifts with very large context windows #19116
• TUI runs out of context with gpt-5.5 despite auto-compact config #19183

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[BillDuke13]

cli v0.124.0 has this issue too

[cccat6]

I read the release page https://openai.com/index/introducing-gpt-5-5/ it says

In Codex, GPT‑5.5 is available for Plus, Pro, Business, Enterprise, Edu, and Go plans with a 400K context window. GPT‑5.5 is also available in Fast mode, generating tokens 1.5x faster for 2.5x the cost.

Which 400K context window is fine for me, and it can keep good proformance. However, 258K is not 400K.
Could Codex fix this ASAP?

[etraut-openai]

The 400K context window includes space for 272K of input + 128K of output. The 258K value is somewhat less than the full 272K to guarantee that compaction is possible. These are the same default values that have been in place for gpt 5.4, gpt 5.3-codex and gpt 5.2.

[Cinea4678]

gpt 5.5 supports 1M context window. Please reopen issue

[IlyaShorin]

The 400K context window includes space for 272K of input + 128K of output. The 258K value is somewhat less than the full 272K to guarantee that compaction is possible. These are the same default values that have been in place for gpt 5.4, gpt 5.3-codex and gpt 5.2.

Sorry, but why did you closed the issue, if the main problem is that 1m tokens context is gone?

[jrenouard]