Same coding task, three routes: one model's own test failed

I ran one small JavaScript repair task through three selectable model routes in the AllRouter playground. The goal was not to prove that one route is universally better. It was to check two things that are easy to reproduce: whether the repaired function works, and whether the model's own tests are internally consistent.

The broken function was:

function normalize(nums) {
  return [...new Set(nums)].sort();
}

The fixed version had to deduplicate values, sort numerically, remove NaN and infinities, and include five runnable console.assert checks. I used the same prompt and the same basic playground settings for each run.

What happened

Selected route label	Result	What I verified
GLM5.2-codex	Pass	The function and all five assertions were coherent. The response stream reported model: GLM5.2, so the selected label and returned model field should be recorded separately.
Kimi-K2.7-Code-codex	Partial pass	The function was correct, but one generated assertion expected both -0 and 0 to survive a Set. JavaScript treats them as the same Set value, so the model's own test failed.
gpt-5.4-mini	Pass	The function and all five assertions were coherent.

The interesting failure was not in the repaired function. It was in the test the model wrote for itself:

console.assert(
  JSON.stringify(normalize([10, 2, 1, 2, -0, 0, NaN])) ===
    '[0,0,1,2,10]'
);

The actual result is [0,1,2,10]. A quick answer review could miss this because the implementation looks right.

This is a deliberately small fixture, not a claim that a relay never changes model behavior. I also did not publish a cost comparison: the playground calls did not appear as reconcilable rows in the current usage-log window, so I do not have billing evidence for this run.

If you want to reproduce it, make one low-risk call first. Save the selected route label, the response model field, the assertion result, and the billing state before deciding whether to add credit:

https://allrouter.ai/register?aff=qjpC&utm_source=devto&utm_content=E1_task_cost_20260723

This URL contains a partner referral parameter. Do not share API keys, private source code, or private prompts.