Why My GPT-4o in Long Context Mode Was Failing and How I Fixed It in Cursor IDE

I was excited to use GPT-4o’s long context mode for coding in Cursor IDE, but kept running into the same headache: my code outputs would cut off halfway through functions. After some digging, I finally cracked why this was happening and found fixes that actually work.

The Core Problem: Output Truncation and Limited Context

At first, I couldn’t figure out why GPT-4o kept stopping mid-response, especially when generating complex functions or analyzing large files. It felt like hitting an invisible wall around 10,000 tokens.

This wasn’t just frustrating – it meant I had to manually stitch together half-finished code snippets. My workflow slowed to a crawl every time it happened.

Discovering the Context Length Update

While troubleshooting, I made a crucial discovery: Cursor IDE had quietly upgraded GPT-4o’s context window from 10k to 20k tokens. That extra breathing room changes everything.

With 20k tokens, you get more space for both your prompts and the AI’s responses. It’s also more affordable than options like Anthropic’s Sonnet. But there’s a catch – you need to set it up properly.

Step-by-Step Fixes I Implemented

Here’s exactly what worked to stop those annoying cutoffs:

• Use Your Own API Key: Head to Preferences > API in Cursor and enter your personal OpenAI key. This often unlocks the full 20k token capacity that shared keys restrict.
• Track Your Token Usage: Enable the context indicator (that percentage bar in your editor). Seeing how full your token “bucket” is helps prevent overloads before they happen.
• Simplify Your Prompts: Break big requests into smaller steps. If the AI stops mid-output, just type “Continue from here” – it usually picks up right where it left off.
• Use Inline Edits: Ctrl+K lets you modify code directly without breaking context. It’s perfect for tweaking functions without starting over.

What I Learned for Smoother Coding

GPT-4o’s expanded context is a real difference-maker when configured right. Keep Cursor updated for the best embeddings, and play with how you balance inputs and outputs within that 20k space.

These tweaks transformed my experience – now I regularly handle large files and complex tasks without those jarring interruptions. It’s amazing what a properly set up workflow can do.