Reliability — idempotency keys, provider fallback, abuse protection

[TheTrueAI]

Phase: 3 — Growth & Scale (Reliability)

Harden the system for production scale:

• Add idempotency keys for pipeline runs — prevent duplicate digests/emails on retries
• Implement provider fallback strategy — graceful degradation when Gemini or SerpAPI is down
• Add anti-abuse controls — basic bot detection and per-email/IP throttling around upload and subscribe endpoints

Critical for maintaining trust when real users depend on daily digests.