Untangling Years of Technical Debt in Trend Analysis

Sometimes the best code you write is the code you delete. This week, I spent the afternoon going through the trend-analysis project—a sprawling signal detection system—and realized we’d accumulated a graveyard of obsolete patterns, ghost queries, and copy-pasted logic that had to go.

The cleanup started with the adapters. We had three duplicate files—tech.py, academic.py, and marketplace.py—that existed purely as middlemen, forwarding requests to the actual implementations: hacker_news.py, github.py, arxiv.py. Over a thousand lines of code, gone. Each adapter was just wrapping the same logic in slightly different syntax. Removing them meant updating imports across the codebase, but the refactor paid for itself instantly in clarity.

Then came the ghost queries. In api/services/, there was a function calling _get_trend_sources_from_db()—except the trend_sources table never existed. Not in schema migrations, nowhere. It was dead code spawned by a half-completed feature from months ago. Deleting it felt like exorcism.

The frontend wasn’t innocent either. Unused components like signal-table, impact-zone-card, and empty-state had accumulated—409 lines of JSX nobody needed. More importantly, we’d hardcoded constants like SOURCE_LABELS and CATEGORY_DOT_COLOR in three different places. I extracted them to lib/constants.ts and updated all references. DRY violations are invisible at first, but they compound into maintenance nightmares.

One bug fix surprised me: credits_store.py was calling sqlite3.connect() directly instead of using our connection pool via db.connection.get_conn(). That’s a concurrency hazard waiting to happen. Fixing it was two lines, but it prevented a potential data race in production.

There were also lingering dependencies we’d added speculatively—exa-py, pyvis, hypothesis—sitting unused in requirements.txt. Comments replaced them in the code, leaving a breadcrumb trail for if we ever need them again.

By the time I finished the test suite updates (fixing endpoint paths like /trends/job-t/report → /analyses/job-t/report), the codebase felt lighter. Leaner. The kind of cleanup that doesn’t add features, but makes the next developer’s job easier.

Tech debt compounds like interest. The earlier you pay it down, the less principal you owe.

Why do programmers prefer using dark mode? Because light attracts bugs. 😄