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Rollback to Prior Map Snapshot

Recovery method — instantiates Context-Keyed Representation Switching

Restores a known-good earlier snapshot of a context's map when the current one is found corrupted, reverting the switch behind a guard rather than repairing in place.

Rollback to Prior Map Snapshot is the recovery move for a map gone bad: when the active representation is discovered corrupted, wrong-versioned, or failing its integrity check, you abandon it and re-activate a trusted earlier snapshot instead of trying to patch the broken one. Its distinguishing property is direction and dependency: it recovers backward to a specific known-good past state, which means it needs a preserved history — unlike falling forward to a generic default that needs no history at all. And the revert is itself a guarded transition, so recovery cannot introduce a fresh corruption of its own.

Example

An operations team runs region-specific targeting-rule maps for a promotions engine on shared infrastructure. A deploy meant for the EU map is misrouted and overwrites the US map; the integrity check flags US divergence within minutes. Rather than hand-patch the mangled US rules, the team invokes Rollback to Prior Map Snapshot: re-point US to the last checkpoint taken before the bad deploy. The revert runs behind a transition guard — drain in-flight requests, load the snapshot, confirm it re-enters cleanly — and only then does the restored map serve traffic. US is back on known-good rules in about two minutes; the EU deploy is redone correctly and separately. No time is spent reasoning about how to un-corrupt the damaged map.

How it works

  • Trigger on an integrity failure, a bad switch, or an explicit human call.
  • Select the restore point — the most recent known-good snapshot, drawn from the checkpoints.
  • Cut over behind the guard — quiesce or drain, load the snapshot, verify clean re-entry, then swap it live.
  • Record the revert so the version register knows the active map moved backward.

Tuning parameters

  • Restore-point selection — newest-good versus a specific blessed snapshot. Newest loses the least work; a labelled "last-blessed" maximizes trust.
  • Guard strictness — how much verification (drain, smoke test, integrity check) before the reverted map serves. More is safer and slower.
  • Blast-radius scope — roll back only the affected context or a wider set. Narrow limits collateral damage; wide is safer if contamination spread.
  • Automation threshold — auto-rollback on integrity failure versus human-approved. Auto is fast but can thrash; human adds latency and judgment.

When it helps, and when it misleads

Its strength is that it bounds the damage of a bad switch or corrupting update to a fast, low-risk "revert to last good" — far safer than in-place surgery on a corrupted map, whenever clean snapshots exist. Its failure modes follow from that dependency: a rollback silently discards every legitimate update made since the snapshot, so you lose good work with the bad; it is useless when no clean checkpoint exists or the corruption predates all retained snapshots; and reflexive auto-rollback can mask a root cause that keeps re-corrupting the map on every attempt. The classic misuse is rolling back again and again to dodge diagnosing why the map corrupts — escalation dressed up as recovery. The discipline that guards against it is to pair rollback with a root-cause hold (do not redeploy into the same failure) and to confirm the restore point is genuinely clean, not merely old.

How it implements the components

Rollback to Prior Map Snapshot fills the recovery subset — the machinery for getting safely back to a trusted state:

  • human_override_and_recovery_path — it is the archetype's recovery path: a human or an automated trigger can abandon a bad map and return the system to a known-good one.
  • switch_transition_guard — the revert is a guarded transition; the guard drains, loads, and verifies the restored map before it goes live, so recovery does not itself corrupt.

It does not preserve the snapshots it restores (that's Per-Context Model Checkpoint), detect that a map is corrupt in the first place (that's Map Difference and Integrity Check), or supply a generic safe map when no good snapshot exists (that's Safe Default-Map Fallback).

Notes

Rollback needs history — a clean prior snapshot to return to. When none exists, the recovery is not backward to a specific good map but sideways to a generic safe one, which is Safe Default-Map Fallback. The two are complementary recovery moves for different situations: rollback when you have a trusted past state, fallback when you do not.