How do you take over maintenance of an existing application?

No, but you need at least to reconstruct the critical points: code, access, environments, dependencies, release procedure, and known incident areas.

It depends on the level of debt and available access, but an initial takeover phase often focuses on making intervention safe before tackling deeper requests.

We first list essential access and possible alternatives. As long as some pieces are not recovered, it must be made clear what remains feasible and what does not.

Yes on targeted requests, but only once risk areas are identified and rollback or diagnostic capacity has been secured.

Yes. Taking over code alone is not enough if the team cannot release, observe, or restore the application properly.

By checking secrets, access, backups, dependencies, deployment procedures, and useful logs before accelerating on evolutions.

Yes, but it makes the mapping and recovery phase more important. In that case, you need to be more rigorous about technical inventory and unknown areas.

An assessment, access list, risk level, critical dependencies, known incidents, and an initial prioritized action plan are often the most useful first deliverables.