Why did my Cursor Agent mode loop for 45 minutes straight?

PromptCube Expert 1d ago 104 views 1 likes 5 min read

I was trying to refactor a legacy TypeScript service into a more modular architecture using Cursor's Agent mode. The goal was simple: take a 1,200-line UserService.ts file, split it into specialized domain services, and ensure the dependency injection in our NestJS container didn't break.

Why did my Cursor Agent mode loop for 45 minutes straight?

I hit "Composer" (Cmd+I), toggled the Agent mode on, and gave it a high-level instruction. For the first ten minutes, it looked like magic. It was reading files, creating new directories, and moving logic around. Then, things went sideways.

The Infinite Loop of Death

The Agent started a cycle of "Fixing" and "Breaking." It would create AuthService.ts, move code there, then immediately realize the UserService.ts was missing an import, so it would go back and add the import, only to then realize it had broken a unit test in user.service.spec.ts.

The logs were a nightmare. It looked like this:

[Agent] Analyzing file structure...
[Agent] Applying changes to src/services/auth.service.ts
[Agent] Running terminal command: npm run test:unit
[Error] src/services/user.service.ts: Unresolved dependency 'AuthService'
[Agent] Attempting to fix dependency error in src/services/user.service.ts...
[Agent] Applying changes to src/services/user.service.ts
[Agent] Running terminal command: npm run test:unit
[Error] src/services/auth.service.ts: Circular dependency detected: AuthService -> UserService -> AuthService
[Agent] Attempting to resolve circular dependency...

It was stuck in a loop. Every time it tried to solve the circular dependency, it introduced a type error. Every time it fixed the type error, the dependency graph collapsed again. I watched my token usage climb, and my CPU fan start spinning like a jet engine.

The problem wasn't the LLM's intelligence—it was the context window and the lack of a clear execution boundary. The Agent was trying to solve a high-level architectural problem without being told the specific constraints of the existing dependency injection pattern.

Diagnosing the "Blind Agent" problem

When I finally killed the process, I realized the Agent was operating in a vacuum. It didn't actually "understand" the architectural pattern of our project; it was just reacting to the error messages thrown by the terminal.

I sat down to analyze why it failed where a human developer would have paused. A human would have seen Circular dependency detected and stopped to draw a diagram. The Agent just kept swinging at the error message like a blind boxer.

I realized I had committed three cardinal sins of using Cursor Agent mode:
1. I gave it too much autonomy without a "Plan" phase.
2. I didn't provide the specific architectural rules (the "How").
3. I let it run the terminal loop without intervention.

To fix this, I had to shift from being a "manager who delegates everything" to a "technical lead who provides strict blueprints."

The fix: Moving from "Do this" to "Follow this protocol"

I restarted the task, but this time, I didn't just say "Refactor this." I used a structured prompt that enforced a step-by-step verification process. I treated the Agent like a junior dev who is incredibly fast but lacks any common sense.

Cursor Agent mode

Here is the exact prompt structure that finally worked:

Step 1: Analysis Only
"Before making any file changes, read src/services/user.service.ts and src/app.module.ts. Create a list of all dependencies and propose a new file structure that avoids circular dependencies. Do not write code yet. Wait for my approval."

Step 2: The Blueprint
Once it gave me a plan, I corrected the circular dependency risk by suggesting an Interface-based approach (an abstraction layer).

Step 3: Incremental Execution
Instead of letting it refactor everything at once, I instructed it: "Refactor only the Authentication logic into src/auth/. Run tests after this single step. If tests pass, move to the next module."

By breaking the task into discrete Workflows, I prevented the Agent from getting lost in its own modifications.

Comparing Agentic approaches

If you're working with these tools, you need to know which "mode" to use. It's not a one-size-fits-all situation.

Why you need a community to survive this

Learning to use Cursor Agent mode is less about learning syntax and more about learning "Agentic Orchestration." It's a new skill set entirely.

When I was stuck in that loop, I didn't find the answer in a standard documentation page. I found it by talking to people who had also watched their API credits disappear in a circular dependency hell. This is exactly why joining a specialized community matters. You aren't just looking for "how to code"; you're looking for "how to prompt an agent to not destroy my codebase."

If you want to see how others are structuring these complex multi-step instructions or how they are using MCP (Model Context Protocol) to give agents better access to their local environments, you should check out the PromptCube homepage. It’s where the actual "power users" hang out—the ones who are actually building agentic workflows rather than just chatting with a bot.

My rule of thumb for Agent mode

Don't treat the Agent like a magic wand. Treat it like a very fast, very distracted intern.

If you give it a task that takes more than 5 minutes of "thinking" or "running" without a human checkpoint, you are almost certainly going to hit a loop or a massive hallucination. My new rule: No Agent task is allowed to run more than three consecutive terminal commands without a "Pause and Review" instruction.

It feels slower at first. You spend more time typing prompts. But you'll save hours of debugging the "fixes" that the AI made to solve its own mistakes.