GPT-5.5/Codex reliability regression: context window error blocks an in-progress app bug fix

Codex Desktop version: 26.519.41501 (3044)

Subscription: ChatGPT Pro

Platform: macOS Tahoe 26.5 on a MacBook Pro 16-inch with Apple M5 Max and 128 GB memory.

Over the last two days, GPT-5.5 in Codex Desktop has felt significantly less reliable for real app debugging and bug-fix work. It has not been able to help me complete app repairs as reliably as before, and the overall Codex experience has felt unstable.

While I was in the middle of fixing an app bug, the existing Codex thread showed this error:

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

This blocked me from continuing the same debugging/fix thread with the original context. Because the fix was already halfway in progress, I had to start a new conversation or clear earlier history, which meant losing the accumulated context from the investigation, logs, screenshots, changed files, constraints, and remaining validation work.

Impact:

• I could not continue a bug fix from the original working context.
• I had to spend extra time reconstructing the task in a new thread.
• This wasted a large amount of usage/tokens and development time.
• It increases the risk of incomplete fixes or regressions because the new thread does not automatically inherit the full prior context.

Feedback ID with session logs uploaded:

019e58c3-fca6-75f0-9512-6876983b86b5

Expected behavior: Codex should compact or provide a safe handoff/continue path before a long-running thread reaches an unrecoverable context-window limit. If a thread must continue in a new conversation, Codex should preserve a structured handoff summary including the current bug, current repository state, changed files, important decisions, remaining work, and validation steps.

Please investigate whether this is a recent GPT-5.5/Codex reliability or context-management regression. The last two days have been particularly unstable for app development work.

<img width="1796" height="420" alt="Image" src="https://github.com/user-attachments/assets/aebb278a-797d-4cc6-8b67-cd531537bac1" />