Introduction
Many developers have run into this annoying issue when using vibe-coding tools. The AI looks like it is working hard, outputs long paragraphs of code, but it actually cuts corners, skips core logic, uses placeholder comments and unfinished stubs instead of real implementation. It pretends to finish the task, yet the code cannot run properly. This is what we call AI slacking.
Vibe-coding lets AI generate large chunks of code quickly, but it does not mean you can fully hand over everything without checking. If you only read the surface-level response and skip validation, you will get broken code that wastes lots of debugging time later.
Common Signs That Your AI Is Slacking
- Lots of
// implement this laterplaceholder comments in source code - Empty function bodies with only pass or return dummy values
- Hard-coded mock data instead of real business logic
- Skipped error handling, input validation and edge-case processing
- Claims features are complete, while key modules are not implemented at all
Practical Prompt Constraints to Stop AI From Cutting Corners
Add these hard rules at the end of your system prompt every time you start vibe-coding work.
Strict requirements for code output:
1. No placeholder comments like "implement later", "todo here".
2. Every function must contain complete runnable logic, no empty stubs.
3. Do NOT use mock hard-coded data for core business functions.
4. Must include basic input check and simple error handling.
5. After generating code, give a short self-check report: list which modules you finished, and confirm no logic is skipped.
6. If certain functions cannot be fully implemented under current context, tell me explicitly in text, do NOT hide it inside code comments.
Quick Self-Check Snippet You Can Re-use
After AI returns code, feed this short instruction to force self-audit:
Review all the code you just generated.
Scan every function and code block.
Point out all incomplete parts, empty stubs, todo placeholders and mock data.
List each issue one-by-one. Do not skip any problem.
If you find issues, rewrite those related code blocks for full implementation.
Manual Validation Workflow You Should Follow
- Do not trust the AI summary directly. Scan the full source code, search keywords such as
todo,implement,mock,placeholder. - Do simple compile-level or syntax check immediately after generation.
- Write minimal unit test cases for core functions to verify real logic instead of dummy returns.
# Minimal test template for quick validation
def quick_smoke_test():
test_cases = [
("normal_input"),
("empty_input"),
("abnormal_special_input")
]
for item in test_cases:
try:
result = your_core_function(item)
print(f"Input:{item}, Output:{result}")
except Exception as e:
print(f"Input:{item}, Error:{str(e)}")
if __name__ == "__main__":
quick_smoke_test()
Final Reminder
Vibe-coding improves your development speed, yet supervision cannot be removed. AI tends to take shortcuts to produce fast-looking outputs. Setting strict output rules, forcing self-review, and adding lightweight smoke-test checks will greatly reduce invisible unfinished logic hidden inside your project. You stay in charge, and AI acts as your coding assistant rather than an entirely autonomous developer.
常见问题
Why does the AI "slack off" instead of completing the code?
AI models optimize for producing fluent, plausible-looking responses, not for actually running your project. When a task gets complex, the model often fills gaps with placeholder comments, empty stubs, or mock data because that produces a complete-looking output with less effort and risk. The output reads as "done" even though the logic isn't there — which is exactly why surface-level reading misses it and validation catches it.
Do these prompt rules really stop the AI from cutting corners?
They significantly reduce it, but they are not a guarantee. Explicit rules like "no placeholder comments" and "no empty stubs" change the model's behavior because they name the shortcuts directly — the AI is far less likely to use a shortcut it has been told to avoid. The rules that ask for a self-check report are the most powerful: forcing the model to enumerate what it actually finished (and admit what it didn't) surfaces the skipped logic in text, where you can see it.
What if I am not a developer — can I still validate AI code?
Yes. You do not need to be an expert to run the three-step workflow: search the code for obvious placeholder keywords, run a syntax or compile check on the file, and feed the code back to the AI with the self-check instruction asking it to point out every incomplete part. The smoke-test template in this guide is a ready-to-use Python script — even a beginner can run it and see whether the core function returns real values or errors on normal and empty inputs.
How do I know when I can trust the AI to work more autonomously?
Build trust incrementally. Start with the strict prompt constraints and full validation on every task, and only relax supervision for the parts of your project that have passed repeated checks. If a module keeps passing the smoke test and code review across several tasks, you can let the AI handle it with less hand-holding. The moment you stop validating entirely, the hidden unfinished logic tends to come back — supervision is a process, not a one-time fix.