Codex Engineer Shares Extended Context Setup for GPT-5.6 Sol
OpenAI Codex engineer Tibo Sottiaux posted configuration steps to unlock the larger window for ChatGPT accounts.
Tibo Sottiaux posted configuration steps for Codex users to set a 1M-token context window with the GPT-5.6 Sol model. The post states the change now works for ChatGPT accounts in addition to API keys. Sottiaux noted the default limit was tuned for performance and cost. Noam Brown replied that he does not recommend increasing the default context size. Other replies discussed autocompaction and tested actual token limits in separate tools.
Here is how to enable a 1M-token context window in Codex for GPT-5.6 Sol. Even though we have tuned the context limit in Codex to be set optimally when it comes to performance and cost, this is a common ask, so here it is documented. A larger context window lets Codex retain…
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17 postsCH 
Chubby♨️@kimmonismusTibo publicly explaining how anyone could extend the context window to 1 million tokens in Codex with GPT-5.6 Sol was not on my bingo card. Anyway, 1m context for everyone in codex:
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T🪽 Teknium 🪽@Teknium@kimmonismus It was wrong fwiw, but they have since opened it up after he said this xD
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V( Vaibhav (VB) Srivastav@reach_vbIf you want to play around with 1M context in Codex, update your config.toml, or just ask Codex to do it: model = "gpt-5.6-sol" model_context_window = 1000000 model_auto_compact_token_limit = 900000 Two caveats: 1. The default context window is already well calibrated and,…
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CH Chubby♨️@kimmonismusQuick reminder: When they first introduced the increased context they said that anything over 272k would consume usage limits at 2x the rate, so be careful when using this!
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T🪽 Teknium 🪽@Teknium@thsottiaux Yea tried to probe this in Hermes Agent, 371k is the actual absolute max..
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T🪽 Teknium 🪽@TekniumWell, this was wrong. The actual server-side max for codex subscriptions is just 360~K. That said, raised the ctx window to 350K in Hermes Agent for codex users. If they expose 1M, will open that up as soon as they do
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