Incompetence can only cover so much,

Overall this looks more like a mix of that and "Let's let someone kill him."

USSS personnel were notified of a suspicious person with a rangefinder around the AGR building approximately 27 minutes before the shooting … [it] was relayed to the USSS Security Room at approximately 5:44 pm and to the USSS Counter Sniper Team Leader at 5:45 pm. Shortly after, USSS personnel, including a Counter Sniper Response agent, engaged in an on-the-ground effort to locate the individual. However, the USSS Lead Advance Agent, Site Agent, and Site Counterpart all told the Committee they did not receive this information and therefore did not know local law enforcement had identified a suspicious person with a rangefinder — and that those local officers later lost track of this individual — until after shots were fired.

USSS was notified about an individual on the AGR roof approximately two minutes before [Thomas M.] Crooks fired from AGR roof.  Three minutes before shots were fired, a local law enforcement officer sent out a radio alert that there was an individual on the AGR roof. This information was passed to the USSS Security Room approximately two minutes before Crooks fired. Approximately 22 seconds before Crooks fired, a local officer sent out a radio alert that the individual on the AGR roof was armed, but that was [allegedly] not relayed to key USSS personnel that the Committee spoke with.

The report continues:

Shortly before shots were fired, a USSS counter sniper saw local law enforcement running toward the AGR building with their guns drawn, but he did not alert former President Trump’s protective detail to remove him from the stage. The USSS counter sniper told the Committee … the thought to notify someone to get Trump off the stage ‘“did not cross [his] mind.”

USSS counter snipers — including the one who shot and killed Crooks — were sent to the rally in response to ‘credible intelligence’ of a threat. The July 13 rally was the first time a USSS counter sniper team was assigned to a protectee other than the President, Vice President, or a presidential candidate who had been formally nominated by his or her party… [but of] the USSS personnel interview by the Committee, nearly all … said they were unaware of any credible intelligence of a threat.

And yes, there's more.  There's a link to the full report, too.  I've only done a quick scan, but I can say this: the table of contents is enough to get your Breakables Alert in effect.