In a welcome development, the Biden administration is leaning in the direction of releasing information from the executive branch that has been demanded by the House select committee investigating the mob attack on the Capitol.

As The Post reports, the White House wants to “err on the side of disclosure given the gravity of the events of Jan. 6.”

That’s important on its own: It shows President Biden and the White House are taking a welcome attitude toward transparency, and probably won’t be cowed by Donald Trump’s threats of legal action to chill such disclosure.

But it turns out this development could dovetail in surprising and revelatory ways with another big revelation: The news of the Trump coup memo, which laid out a detailed scheme for Vice President Pence to ignore federal law to simply declare Trump the winner of the election.

The news of that memo should prompt us to look back at the Jan. 6 committee’s expansive demand for executive branch documents from last month. That demand sought documents from a wide range of agencies that could shed light on the conduct of Trump, many of his advisers, and even members of Congress in the lead up to Jan. 6.

Guess who one of the Trump advisers named in that document demand turns out to be? The author of the Trump coup memo, lawyer John Eastman.

The Jan. 6 committee’s letter to the National Archives demands extensive documents from the White House, including those concerning plans to impede the count of the electoral college in Congress.

In that letter, the committee mentions Eastman twice: It demands communications and legal analysis by Eastman and other Trump advisers and lawyers involving complying with certifying electors. Those others include White House lawyers like Pat Cipollone and Patrick Philbin.

And it demands all documents and communications to or from Eastman from November through Jan. 20, a period that of course encompasses the plotting to subvert the election in Congress.

It’s not hard to surmise where this might lead. Eastman’s memo argued that Pence could ignore the law and refuse to count Biden’s electors. If Republicans in swing states sent rogue electors for Trump, Pence could simply declare that neither rightful Biden electors nor rogue ones were valid, leaving Trump the winner of a majority of remaining electors.

A big question will be whether other people around Trump were in on this scheme — whether they endorsed it or helped develop or try to implement it. The plot is so radically antidemocratic that anyone who did so will face serious public and maybe professional censure at the least.

So it seems clear such a request for documents could find communications about this scheme, as well as discussions about how to put it into motion and who was on board with it, among people beyond Eastman. We don’t know if that will happen, but the committee will now want to determine how deep this ran.

Also note that Trump, Pence and Eastman met in the White House on Jan. 4, where Trump urged Pence to listen to Eastman. Pence ultimately rebuffed this pressure, but the committee will surely want to know more about this meeting.

“This was a coup conducted by the president — against his own vice president and the Congress,” Rep. Jamie Raskin (D-Md.), a member of the Jan. 6 committee, told me. “We are actively investigating both the organization of the bloody insurrection and the planning of the coup against American democracy. Both of them were attacks on the constitutional order.”

As it is, broadcast news has been weirdly reluctant to cover the story of the Trump coup memo, even though the plot is right there in writing. But if the committee digs in and finds more about it, that might prove harder to ignore.

More broadly, the committee appears to want to perform a reckoning that goes far beyond the mob violence, and digs deeply into just how concerted and extensive a scheme there really was to keep Trump in power illegitimately and to thwart a legitimately elected government from taking over.

The Biden White House’s apparent instinct to be transparent, and the fact that the probe is digging around for more information about the author of the Trump coup memo and his machinations, suggest the reckoning could prove more unpleasant and revelatory than we expect.