WASHINGTON — President Trump and his allies spent months promising that a report on the origins of the F.B.I.’s Russia investigation would be a kind of Rosetta Stone for Trump-era conspiracy enthusiasts — the key to unlocking the secrets of a government plot to keep Mr. Trump from being elected in 2016.

On that point, the report by the Justice Department’s inspector general, Michael E. Horowitz, did not deliver, even as it found serious problems with how F.B.I. officials justified the surveillance of a Trump campaign aide to a federal court.

But by the time it was released, the president, his attorney general, his supporters in Congress and the conservative news media had already declared victory and decamped for the next battle in the wider war to convince Americans of the enemies at home and abroad arrayed against the Trump presidency.

They followed a script they have used for nearly three years: Engage in a choreographed campaign of presidential tweets, Fox News appearances and fiery congressional testimony to create expectations about finding proof of a “deep state” campaign against Mr. Trump. And then, when the proof does not emerge, skew the results and prepare for the next opportunity to execute the playbook.