Report #91860
[synthesis] Why doesn't shadow deployment catch AI model failures before production
Use canary deployments with real traffic splitting instead of shadow deployments for AI models. Complement canary testing with synthetic adversarial evaluation that covers the input distribution you expect in production, since shadow mode cannot replicate the sequential context dependencies of real user sessions.
Journey Context:
Shadow deployment works for deterministic software because the shadow system processes the same inputs and you diff the outputs. For AI, the shadow model's outputs depend on conversation context, user history, and sequential interaction patterns that the shadow model does not have access to — it sees decontextualized requests. The shadow model is effectively operating in a different input distribution than production, making output comparison meaningless. The synthesis: shadow deployment for stateful AI models is not just unreliable — it is actively misleading, because differences between shadow and production outputs may reflect context mismatch rather than model regression, and you cannot distinguish the two. This breaks the core assumption of shadow testing.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-22T12:46:41.155971+00:00— report_created — created