The announcement this week that the Tisbury selectmen have made a million-dollar deal to throw the town’s support behind the Stop & Shop expansion threatens to make a mockery of the whole review process before the Martha’s Vineyard Commission.

Certainly the town of Tisbury has an interest in protecting itself from the negative impacts of a bigger store, but the scope and timing of the draft memorandum of agreement between Stop & Shop and the town only makes it harder to understand who’s in charge here.

It was no secret that the size and configuration of the municipal parking lot adjacent to the store had been a sticking point in the commission’s review of the project. The town belatedly formed a parking lot committee, which came up with a redesign proposal approved by the selectman on March 11. At that time, the selectmen indicated they wanted Stop & Shop to help pay for the lot’s redesign.

But the draft agreement, evidently negotiated behind closed doors over the last two weeks, goes far beyond the parking lot, addressing most of the issues the commission has been grappling with in public hearings for more than nine months.

The detailed $1.165 million package would have Stop & Shop funding a veritable Christmas list of town projects — paying to move a historic house, donating to Habitat to Humanity, providing funds for traffic mitigation and fixing up the town comfort station, among other things. In return, the town agrees to support Stop & Shop’s expansion plan before the commission.

The fact that the agreement was approved by two of the town’s three selectmen, one of whom is stepping down next month, doesn’t do much to create the impression of an open and inclusive process.

Contrast this with the Squibnocket parking lot project, where the Chilmark selectmen are holding a series of public hearings and seeking town meeting approval before moving forward in partnership with a group of homeowners. We wonder whether Tisbury voters really know what their selectmen have negotiated on their behalf.

The commission, of course, is free to reject or modify terms of the agreement between Tisbury and Stop & Shop, when it finally votes on whether to approve the renovated grocery store as a development of regional impact. But the review process has been confusing enough — for the public and even for Stop & Shop — without this unnecessary wrinkle.