Regime Change Response

• Recognize regime change versus ordinary drift
• Run triage, containment, and accelerated refresh
• Keep the governance trail for a structural event

• Normal drift logic (wait, re-baseline) is too slow for structural breaks.
• The old reference window is now actively misleading — it must be replaced, fast.
• Retraining on pre-regime labels 'institutionalizes' the dead world.
• Regime events carry compliance and stakeholder obligations — governance matters.

You don't keep driving and 'adjust for jitter' — you stop, assess damage, route traffic, and redesign with the new structure in mind. Normal drift was a slow flex of the road; regime change is the earthquake: containment, then rebuild with a new model of the world.

• Triage the alert: sustained, structural, multi-metric collapse → escalate to regime tier.
• Contain: halt or defer high-stakes decisions; fall back to safer defaults or locked lanes.
• Reconstruct the window: training data post-breakpoint only, labels scrubbed for the new semantics.
• Accelerate: shorten cycles, expedite human-in-the-loop labeling, prototype on the new window.
• Govern: record the break, the decision, the stakeholders, and the rollback/retrain evidence.

• A pandemic-era travel forecast breaks: regime triggered, booking predictions halted, demand rebaselined from new-data windows.
• A credit model breaks on new legislation: exposures paused while the team rebuilds on the new legal semantics.
• A recommender's platform relaunch inverts engagement: regime flags, cold-start lanes enabled, retrain on the post-launch window.

• Pre-define what escalating to 'regime' requires: sustained, structural, multi-signal collapse.
• Make containment choices explicit and reversible (defer, not destroy).
• Rebuild ONLY on post-breakpoint windows with scrubbed label semantics.
• Log the regime incident like an outage: owners, timeline, decisions, evidence.

• Applying ordinary-drift latency to a structural break — retraining too late on dead semantics.
• Including pre-regime data in the new window, polluting the new reality.
• Hitting default thresholds instead of deferring decisions the model can't support.
• Skipping governance — an undocumented regime reroute fails compliance and audit review.

• Regime retrain still bad — the window includes pre-break data; verify post-breakpoint slices only.
• Containment didn't hold — fallback lanes silently reused the broken model; check the routing logic.
• Alert fired for a 'regime' that was actually a data-platform outage — triage separated signal from plumbing.