The fear is reasonable: an outside team builds your product, and eighteen months later you cannot change anything without them. It happens, and it is preventable with arrangements that are entirely normal to ask for.
Own the accounts from day one
Repository, cloud accounts, domain, database, app store listings — all in your organisation's name, with the agency granted access. This single arrangement removes most lock-in risk permanently, and any agency that resists it is telling you something important about how they retain clients.
If leaving would be difficult, that difficulty was designed in. Insist it is not.
Weekly working software, not status decks
A slide saying 70% complete is unverifiable. A deployed environment you can use is not. Insist on something running that you can click through every week — this catches misunderstandings while they are cheap and makes progress a fact rather than a claim.
Require documentation as a deliverable
Architecture notes, environment setup, deployment procedure and the reasoning behind significant decisions, in the repository. If this is not a named deliverable it will not exist, and its absence is what makes transitions painful regardless of code quality.
Rehearse the handover early
Six months in, ask a developer who has never touched the project to set it up from the documentation alone and make a small change. Whatever they get stuck on is exactly what would block you in a transition. Finding that out while the agency is still engaged is the entire point.
Keep the product decisions
Delegating engineering is sensible; delegating what to build is not. Priorities, tradeoffs and what the product is for should stay with you. A good agency will argue with your decisions, which is useful — but the decision should be yours, because you carry its consequences.
Plan the exit at the start
Agree notice periods, handover scope and post-engagement support before signing, when both sides are cooperative. Negotiating an exit during a disagreement produces worse terms and worse outcomes. A clean, pre-agreed exit also tends to make the relationship better, because neither side is quietly managing the risk of the other leaving.
