William Straus is heading a probe of the Registry of Motor Vehicles. On Friday, he said there appears to be an untold number of documents the Baker administration has not turned over to the committee — documents that could help shed light on key periods of failure within the agency.

A split-development proposal that straddles Brookline and Brighton is an example of how varying visions undermine efforts to reduce the problem of sky-high costs and dwindling supply.

The sudden dissension largely stems from an amendment senators passed last week reworking details of a measure designed to strengthen accountability of school districts. Senators said they were clarifying it. Critics, including Charlie Baker, say they weakened it.