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Ever since GPT-5.5 was released, the context window has been stuck at only 272k. Any related discussion gets immediately closed by staff with the "openai" suffix.
At this point, 272k context is practically unusable in codex. I run into context compression failures more than once a day, and each thread averages five to six context compressions. Every compression noticeably degrades work capability and causes the model to forget things.
Why not give us back the 1M context? Even an option like a [1m] toggle like the one in claude code wouldn't work? Consume more credits if you have to. Why actively downgrade developers' experience?
If you're worried about compute capacity, don't enforce any actual limit on the server side—just let us flip this hidden option through an env variable so that those who need it can enable it. Would that really be so hard?
I don't think this is a technical limitation—it's a cost issue. The actual API cost of Codex subscriptions likely far exceeds the subscription price, and supporting a 1M-token context window would only drive those costs much higher. At least for now, OpenAI probably isn't planning to absorb that expense for developers.
Right now, Codex is geared more toward localized feature improvements and is still far from being able to replace CC. As long as the context window doesn't grow, it won't be able to handle large-scale architectural tasks.
I don't think this is a technical limitation—it's a cost issue. The actual API cost of Codex subscriptions likely far exceeds the subscription price, and supporting a 1M-token context window would only drive those costs much higher. At least for now, OpenAI probably isn't planning to absorb that expense for developers. Right now, Codex is geared more toward localized feature improvements and is still far from being able to replace CC. As long as the context window doesn't grow, it won't be able to handle large-scale architectural tasks.
So I don't think developers need to keep pushing Codex to support a 1M-token context window. Once OpenAI is rich enough, they'll support it naturally.
I don't think this is a technical limitation—it's a cost issue. The actual API cost of Codex subscriptions likely far exceeds the subscription price, and supporting a 1M-token context window would only drive those costs much higher. At least for now, OpenAI probably isn't planning to absorb that expense for developers. Right now, Codex is geared more toward localized feature improvements and is still far from being able to replace CC. As long as the context window doesn't grow, it won't be able to handle large-scale architectural tasks.
They can set a higher price, and I'm willing to pay more for it.
I don't think this is a technical limitation—it's a cost issue. The actual API cost of Codex subscriptions likely far exceeds the subscription price, and supporting a 1M-token context window would only drive those costs much higher. At least for now, OpenAI probably isn't planning to absorb that expense for developers. Right now, Codex is geared more toward localized feature improvements and is still far from being able to replace CC. As long as the context window doesn't grow, it won't be able to handle large-scale architectural tasks.
They can set a higher price, and I'm willing to pay more for it.
The subscription price is already far below the actual API cost. Even charging developers a few hundred dollars more wouldn't be enough to cover the additional cost of supporting a 1M-token context window.
It was implied in the original issue that this would be implemented. It's honestly the only item stopping me from cancelling my Claude sub and going all in OpenAI.
Noticed the same drop — went from 1M to 272K mid-sprint.
Coincidentally, I've been working on a methodology for exactly this scenario: Deterministic Context Routing (DCR) — structured context management designed for short-window agent sessions. Module registry, layered knowledge base, session state with stop markers, confidence labels. The idea is to route only what's needed instead of dumping everything into one window.
There's a write-up here: https://github.com/ai-erp-collab/deterministic-context-routing
It helps with large, raw-data-heavy projects — the kind where you'd normally burn through context just navigating the workspace. ERP development, multi-module codebases, that sort of thing.
Might be useful if the window stays where it is.
It's not dropping midsprint. It will show 1M before you send the first prompt and then will update right after that or after the first response. Which probably means you configured codex to use 1M, but it can't and only updates the UI when you try.
The 580,000 value is a deliberate safety threshold. It gives Codex substantial room to compact before the available approximately 828,400-token usable limit. It is not a claim that the model has a one-million-token context window.
The current behavior is unacceptable from a usability and transparency perspective. Codex silently starts supported models at approximately 258,400 usable tokens even though the same delivered catalog lists an 872,000 raw maximum. Users should not have to inspect model-cache files, source code, configuration fields, and rollout JSONL to understand why a session compacted or how much context it actually has.
Codex should visibly report:
Active raw context window.
Effective usable context.
Catalog maximum.
Configured automatic-compaction threshold.
Effective threshold after clamping.
Whether the value came from the model catalog, local configuration, or a remote override.
Whether compaction created a replacement context window.
Whether a resumed or compacted task retained the configured context profile.
My current task still reports 258,400 usable tokens because the 872,000 override was not active when that task was created. I will verify the result in a freshly started Astra task after applying the configuration.
If the fresh task reports 828,400, the hidden override works, but the 272K default and absence of visible active/max/compaction telemetry remain serious discoverability problems.
If the fresh task still reports 258,400, Codex Desktop is not honoring the explicit override or the catalogued 872K maximum.
AI helped reconstruct the configuration and session evidence. I reviewed and verified the claims before publication.
Activity
github-actions commentedon Jul 2, 2026
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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reliefeai commentedon Jul 2, 2026
no dublicate.
LimLex commentedon Jul 2, 2026
I don't think this is a technical limitation—it's a cost issue. The actual API cost of Codex subscriptions likely far exceeds the subscription price, and supporting a 1M-token context window would only drive those costs much higher. At least for now, OpenAI probably isn't planning to absorb that expense for developers.
Right now, Codex is geared more toward localized feature improvements and is still far from being able to replace CC. As long as the context window doesn't grow, it won't be able to handle large-scale architectural tasks.
LimLex commentedon Jul 2, 2026
So I don't think developers need to keep pushing Codex to support a 1M-token context window. Once OpenAI is rich enough, they'll support it naturally.
reliefeai commentedon Jul 2, 2026
They can set a higher price, and I'm willing to pay more for it.
LimLex commentedon Jul 2, 2026
The subscription price is already far below the actual API cost. Even charging developers a few hundred dollars more wouldn't be enough to cover the additional cost of supporting a 1M-token context window.
wjarka commentedon Jul 7, 2026
It was implied in the original issue that this would be implemented. It's honestly the only item stopping me from cancelling my Claude sub and going all in OpenAI.
ai-erp-collab commentedon Jul 8, 2026
Noticed the same drop — went from 1M to 272K mid-sprint.
Coincidentally, I've been working on a methodology for exactly this scenario: Deterministic Context Routing (DCR) — structured context management designed for short-window agent sessions. Module registry, layered knowledge base, session state with stop markers, confidence labels. The idea is to route only what's needed instead of dumping everything into one window.
There's a write-up here: https://github.com/ai-erp-collab/deterministic-context-routing
It helps with large, raw-data-heavy projects — the kind where you'd normally burn through context just navigating the workspace. ERP development, multi-module codebases, that sort of thing.
Might be useful if the window stays where it is.
wjarka commentedon Jul 10, 2026
It's not dropping midsprint. It will show 1M before you send the first prompt and then will update right after that or after the first response. Which probably means you configured codex to use 1M, but it can't and only updates the UI when you try.
Ahoo-Wang commentedon Jul 20, 2026
Fable 5: 1M. K3: 1M. GLM-5.2: 1M. Grok 4.5: 500K. GPT-5.6 Sol API: 1.05M. In Codex: 272K.
OpenAI built a frontier brain and locked it in a toy cage. 272K isn’t context.
It’s a README with delusions of grandeur. Codex didn’t deploy Sol. It imprisoned it.
otmanm commentedon Sep 9, 2026
My request is not for a one-million-token context window.
The current Codex catalog on my machine reports the following for Astra and GPT-5.6:
My intended configuration is:
The 580,000 value is a deliberate safety threshold. It gives Codex substantial room to compact before the available approximately 828,400-token usable limit. It is not a claim that the model has a one-million-token context window.
The current behavior is unacceptable from a usability and transparency perspective. Codex silently starts supported models at approximately 258,400 usable tokens even though the same delivered catalog lists an 872,000 raw maximum. Users should not have to inspect model-cache files, source code, configuration fields, and rollout JSONL to understand why a session compacted or how much context it actually has.
Codex should visibly report:
My current task still reports 258,400 usable tokens because the 872,000 override was not active when that task was created. I will verify the result in a freshly started Astra task after applying the configuration.
If the fresh task reports 828,400, the hidden override works, but the 272K default and absence of visible active/max/compaction telemetry remain serious discoverability problems.
If the fresh task still reports 258,400, Codex Desktop is not honoring the explicit override or the catalogued 872K maximum.
AI helped reconstruct the configuration and session evidence. I reviewed and verified the claims before publication.