Prompt Drift After a Model Upgrade
ProofMap compares prompt behavior across your baseline runtime and challenger runtime so you see exactly which objectives regressed — before you ship the upgrade.
Get StartedWhy Choose ProofMap
Detect regressions with objective-bound tests
Define measurable outcomes for each prompt. ProofMap runs those same objectives against every runtime candidate and flags statistically significant regressions automatically.
Compare baseline runtime versus challenger runtime
Run your prompts side-by-side on your current production model and any new model you are evaluating. See pass/fail rates, latency deltas, and output evidence per objective.
Approve runtime-specific prompt packages instead of guessing
When prompts need runtime-specific adjustments, ProofMap lets you approve a distinct prompt package per target runtime — no more one-size-fits-all prompt files that silently fail after an upgrade.
Comparison
| Concern | Manual workflow | ProofMap |
|---|---|---|
| Finding regressions | Spot-check a handful of outputs; guess whether the new model is worse | Run objective-bound tests across both runtimes; see pass/fail evidence per prompt |
| Separating prompt issue from runtime issue | Revert the model and re-test manually on the old runtime; no structured A/B | Compare baseline runtime against challenger runtime with the same test suite; isolate the delta |
| Choosing whether to stay, switch, or fallback | Ship and pray; discover failures in production logs | Decide based on side-by-side evidence: approve a runtime-specific prompt package or map a fallback runtime |
| Knowing which prompt package should run | Every runtime gets the same prompt file regardless of how that model behaves | Assign an approved prompt package per target runtime; each package backed by regression evidence |
Frequently Asked Questions
What is prompt drift after a model upgrade?
When you switch the underlying model your agent calls, the same prompt can produce different — often worse — results. That behavioral shift is prompt drift. It happens because different models interpret instructions, handle edge cases, or bias responses differently even when the prompt text does not change.
How is this different from generic eval tooling?
Generic eval tools answer "how good is this prompt?" ProofMap answers "does this prompt still work on this runtime?" by comparing a known baseline to a challenger and showing you which specific objectives regressed.
Can I compare my current production runtime to a challenger?
Yes. You define a baseline runtime (your current production model) and one or more challenger runtimes. ProofMap runs your objective-bound tests against each and surfaces the evidence side by side.
What happens if only some runtimes qualify?
You do not have to ship a single prompt everywhere. ProofMap lets you approve a prompt package for each target runtime, so you can roll forward on qualified runtimes while keeping a fallback on the rest.
Start qualifying prompts
Run your first baseline-to-challenger comparison. See evidence before you ship.
Start qualifying prompts