# 3 Bugs I Fixed Before Shipping My WhatsApp AI Receptionist > Source: > Published: 2026-10-20 06:12:37+00:00 My WhatsApp AI receptionist answered pricing questions, booked appointments, and handed off to a human. The demo worked. Then a production review exposed three bugs in its knowledge pipeline: **CSV/PDF/URL → chunks → Postgres.** Deduplication compared incoming chunks against the previous version. Unchanged chunks were discarded as duplicates—then deleted when the old version was replaced. A 10% update left just 10% of the knowledge. No error. Just missing answers. **Fix:** Identify the previous version before deduping, exclude its chunks from the comparison, and replace it in one transaction. Add a regression test. A `SELECT` followed by an `UPDATE` let two workers pick the same pending source. **Fix:** Claim it atomically: ``` UPDATE knowledge_sources SET status = 'processing' WHERE id = $1 AND status = 'pending' RETURNING *; ``` No returned row means no claim. That worker skips ingestion. A submitted URL could send the server to localhost, internal services, or cloud metadata—including through redirects. **Fix:** Add URL-fetch safeguards: allow HTTP(S) only, check resolved IPs for internal destinations, revalidate every redirect, and cap responses at 5 MB. These fixes shipped in **v0.5.0**, with **30 tests** using Node’s built-in runner. A working conversation is only part of the test. Re-uploads, competing workers, and untrusted URLs deserve their own. **Which of these has caught you before? My bet: the check-then-act race.** *— Sajib, full-stack developer from Dhaka · [sajib.dev.cv](https://sajib.dev.cv)*