r/ClaudeAI: Claude Opus 4.8 Hallucinates Sources in News Curation Tasks That Sonnet 4.5 Handled Reliably

A developer reports in r/ClaudeAI that Claude Opus 4.8 repeatedly hallucinates sources when used to curate a daily news newsletter — generating convincing but fabricated article citations attributed to real publishers — a task that Claude Sonnet 4.5 handled reliably roughly seven to eight months earlier. The post describes asking Opus 4.8 for daily news items with real sources only to receive high-confidence fabrications with plausible-sounding headlines. The regression surfaces a potential quality gap between Opus 4.8's reasoning improvements and its source attribution reliability on structured curation workflows.