Problem

LINE is the only non-Telegram channel that sends a user-visible fallback message on dispatch failure, but it uses a hardcoded generic string via a bare try/catch rather than the typed error routing introduced for Telegram.

Current LINE fallback (src/line/monitor.ts):

"Sorry, I encountered an error processing your message."

This does not distinguish between rate limits, empty provider responses, or general errors.

Proposed fix

Replace the hardcoded fallback with the same resolveFailoverReasonFromError + EmptyResponseError routing used by Telegram, once the shared helper from #60812 is available.

Related

• Broader channel fallback tracking: fix(channels): extend user-visible error fallback to Discord, Slack, Signal, WhatsApp #60812
• EmptyResponseError introduced in the model-fallback empty-response fix PR