What Happens Before QCUL Installs an Update in the Laboratory

Before installation begins, QCUL captures enough state to make the laboratory test explainable and undoable rather than changing the clone immediately.

Pre-install sequence

• Confirms the selected update belongs to the active lab and is currently testable.
• Captures/resolves the exact package and verifies SHA-256.
• Creates a laboratory restore point for current files/database in restartable batches.
• Captures baseline evidence used for before/after comparison.
• Refreshes/applies the current QCUL runtime so an older restore point cannot overwrite the signed installer endpoint.
• Acquires the relevant operation/run locks before changing the lab.

Why the restore point comes first

Undo Lab Update is meaningful only if the pre-test state was captured before the installer modifies files/tables. If checkpoint creation cannot complete, QCUL should not pretend the later test is safely undoable.

Production remains untouched

All of this preparation is scoped to the private lab and QCUL’s private run storage. The production site is not installed/modified until a later explicit Push to Production.

Keep the evidence chain intact

The value of What Happens Before QCUL Installs an Update in the Laboratory depends on preserving one traceable transition: known starting version, one selected update, exact captured package/hash, resulting laboratory version, automated evidence, and human review. Avoid manual package installs or unrelated lab changes that make that chain ambiguous before a production decision.

Community Discussion

Want to compare update-testing workflows, share practical tips, or discuss how you use this QCUL feature? Visit the QC Update Laboratory Community. For private support, bug reports, account-specific issues, or feature requests, use the QuantaCade support system.