Codex GPT 5.6 Sol Reduced to 258K Context Window

OpenAI silently reduced the usable context window for its GPT-5.6 Sol model in Codex CLI from 353,400 tokens to 258,400 tokens, a 26.9% cut, despite the model being advertised with a 1.05 million-token context window. The reduction was discovered by a user who reported it as a severe regression, noting that the change was made without notice and undermines trust in the platform for professional development tasks.

- Notifications /login?return to=%2Fopenai%2Fcodex You must be signed in to change notification settings - Fork 14.5k /login?return to=%2Fopenai%2Fcodex 🚨 SEVERE REGRESSION GPT-5.6 Sol context cut again: 353K → 258K despite advertised 1.05M 32806 CLIIssues related to the Codex CLI https://github.com/openai/codex/issues?q=state%3Aopen%20label%3A%22CLI%22 Issues related to the Codex CLI bugSomething isn't working https://github.com/openai/codex/issues?q=state%3Aopen%20label%3A%22bug%22 Something isn't working contextIssues related to context management including compaction https://github.com/openai/codex/issues?q=state%3Aopen%20label%3A%22context%22 Issues related to context management including compaction Description What version of Codex CLI is running? codex-cli 0.144.3 What subscription do you have? Paid ChatGPT-authenticated Codex subscription. Exact tier is redacted for privacy because the catalog/runtime regression is not account-specific. Which model were you using? gpt-5.6-sol What platform is your computer? Linux x86 64. Exact host and kernel details are redacted because they are unrelated to server-delivered model metadata. What terminal emulator and version are you using if applicable ? Codex desktop/CLI environment. Local application and project identifiers are redacted. Codex doctor report Not included to avoid publishing machine, account, path, repository, and runtime metadata. The relevant sanitized version, model-catalog fields, and runtime values are included below. What issue are you seeing? Summary Codex has silently reduced the usable context window for gpt-5.6-sol again . The previous server-delivered Codex model catalog exposed: { "context window": 372000, "max context window": 372000, "effective context window percent": 95 } That produced a 353,400 -token effective runtime window: 372,000 × 95% = 353,400 The current freshly fetched catalog now exposes: { "context window": 272000, "max context window": 272000, "effective context window percent": 95 } Codex therefore now reports only 258,400 effective tokens: 272,000 × 95% = 258,400 This is a further 95,000-token / 26.9% reduction from the already restricted 353.4K Codex window. It is not UI rounding. Sanitized historical runtime records repeatedly report model context window: 353400 before the rollout and model context window: 258400 afterward. No local model context window or auto-compaction override is configured. Issue 31860 https://github.com/openai/codex/issues/31860 already documented that the earlier 353.4K Codex cap was far below the published GPT-5.6 Sol model specification. This report covers the new and materially worse regression from 353.4K to 258.4K. The official GPT-5.6 Sol model page still advertises: - 1,050,000-token context window - 922,000 maximum input - 128,000 maximum output Source: https://developers.openai.com/api/docs/models/gpt-5.6-sol https://developers.openai.com/api/docs/models/gpt-5.6-sol At the same 95% effective-window policy, the advertised model would provide approximately 997,500 usable tokens. Codex now exposes only 258,400 , or 25.9% of that comparable effective capacity. Why this is unacceptable This combination is infuriating: OpenAI advertises a 1.05M flagship model, initially restricts it to 353K in Codex, and then silently cuts it again to 258K. Paying users are left with more compactions, lost working context, disrupted long-running tasks, and no advance notice or explanation. This feels dismissive of paying users and materially undermines trust in Codex as a professional development tool. Repository-scale analysis, long-running implementation work, multi-agent coordination, large specifications, and tool-heavy sessions all depend on stable context capacity. Context size is not a cosmetic setting that can be silently reduced by another 26.9%. The pricing situation makes this even more frustrating. The same official model page states that requests above 272K input are priced at 2× input and 1.5× output for the full request. Codex now caps the raw window at exactly 272K, so users cannot even choose to access the published long-context tier through Codex. To be precise: this report concerns the Codex product limit under ChatGPT authentication. The pricing comparison refers to OpenAI's published API long-context policy; it demonstrates that long-context capacity exists and is explicitly priced, while Codex prevents access to it. Major competing platforms already offer 1M-class context: - Google documents Gemini models with 1M or larger context windows: https://ai.google.dev/gemini-api/docs/long-context https://ai.google.dev/gemini-api/docs/long-context - xAI documents a 1,000,000-token window for its flagship Grok 4.3: https://docs.x.ai/developers/models/grok-4.3 https://docs.x.ai/developers/models/grok-4.3 - Anthropic documents a 1M context option for Claude Sonnet 4: https://docs.anthropic.com/en/docs/about-claude/pricing https://docs.anthropic.com/en/docs/about-claude/pricing A flagship coding product limited to 258K effective context is no longer competitive, especially when its underlying OpenAI model is publicly specified at 1.05M. What steps can reproduce the bug? - Run Codex CLI 0.144.3 with the official OpenAI provider and ChatGPT authentication. - Select gpt-5.6-sol . - Ensure there is no local model context window , model auto compact token limit , provider, or project override. - Fetch or refresh the server-delivered model catalog. - Inspect the sanitized gpt-5.6-sol catalog entry. - Observe context window: 272000 , max context window: 272000 , and effective context window percent: 95 . - Start or continue a thread and inspect token-usage metadata. - Observe model context window: 258400 . - Compare with earlier sanitized GPT-5.6 Sol thread records, which report model context window: 353400 . The transition was observed on 2026-07-13. Old and new values briefly overlapped across existing and newly started threads, consistent with a phased or cached server-side catalog rollout. What is the expected behavior? - Codex should expose the full published 1.05M GPT-5.6 Sol context window, with a clear effective input/output reserve. - If a product-specific cap is unavoidable, it must be prominently documented before users select the model. - Context limits must not be silently reduced for existing or new paid-user workflows. - Active threads should retain the context contract under which they were started. - Users should be allowed to opt into the published long-context tier when they accept the associated usage or pricing impact. - As an immediate stopgap, restore the previous 372K raw / 353.4K effective Codex limit while full 1.05M support is implemented. - OpenAI should explain why the context was reduced, whether the change is temporary, which plans/surfaces are affected, and how usage accounting interacts with this cap. Additional information Related reports: Critical Codex App GPT-5.6 Sol is catalog-capped at 372K 353.4K effective vs the 1.05M model spec 31860 https://github.com/openai/codex/issues/31860 — GPT-5.6 Sol was already capped at 372K raw / 353.4K effective instead of the published 1.05M. Context window changes from 1M to 258K mid-thread 29039 https://github.com/openai/codex/issues/29039 — a GPT-5.5 thread changed from 1M to 258K mid-thread. Reopen 19464 and support 1M context 30910 https://github.com/openai/codex/issues/30910 — request to restore 1M context support. Privacy note: this report intentionally excludes account identifiers, thread IDs, repository names, local paths, prompts, transcripts, and exact machine metadata. Only model metadata and aggregate context-window observations required to reproduce the regression are included. Metadata Metadata Assignees Labels CLIIssues related to the Codex CLI https://github.com/openai/codex/issues?q=state%3Aopen%20label%3A%22CLI%22 Issues related to the Codex CLI bugSomething isn't working https://github.com/openai/codex/issues?q=state%3Aopen%20label%3A%22bug%22 Something isn't working contextIssues related to context management including compaction https://github.com/openai/codex/issues?q=state%3Aopen%20label%3A%22context%22 Issues related to context management including compaction