The CircleCI Cache Key Bug That's Silently Serving Your Builds Stale Dependencie

<p>This is a submission for DEV's Summer Bug Smash: Clear the Lineup.</p> <h2> The bug </h2> <p><a href="https://npmx.dev" rel="noopener noreferrer">npmx.dev</a> is a fast browser

<p>Build times, especially in enterprise software projects, are often an overlooked bottleneck that leads to significant inefficiencies. While working on a production ERP,

<p>I spent an afternoon debugging a component that kept re-fetching on every single request.</p> <p>It had <code>'use cache'</code> right there in the code. I was confident it was

<p>Your agent passed all the tests. It's been running in production for three weeks. And it has been quietly wrong the entire time.</p> <p>This is not a hypothetical. Galileo's

<p>If you've ever opened DevTools and watched the same API call fire <strong>over and over again</strong> — for data that hasn't changed in hours — this article is for you.</p>

<p>60% of my $312 Anthropic bill last month came from a single bug: an MCP router cache key that was missing a tenant ID.</p> <p>The fix was literally this:<br /> </p> <div

<p>I lost hours debugging a Next.js 16 caching issue that had no error, no warning, and only showed up in production.</p> <p>The Next.js 16 caching model is genuinely good. But it