For the shop that's already in it
Stop absorbing it. Start recovering.
You know roughly when it started. A request that felt too small to push back on. A meeting that wasn't in scope but seemed easier to attend than explain. A change that arrived framed as a clarification. None of it was a big ask on its own. Together it has cost you more than you quoted for the whole job.
The Engagement Recovery starts with understanding exactly where you are. That means a briefing from you, a review of the SOW and MSA, and a session to work through the gap between what the contract says and what is actually happening. The output is a game plan: what your position is, what is recoverable, what needs to be said to the client and how, and what to do from here.
You implement it. Some clients do that cleanly and don't need anything else. Others are in the middle of a relationship that still has months to run and want someone available while they work through it.
If you need ongoing support while you work through it, that's what the retainer is for. Ten hours a month, used how you need them, batched around what comes up. Month to month. The game plan is already done. The retainer is for the execution.