It appears to me after studying numerous similar situations now that according to many activists, the answer to your question is to permit demonstrators to gather without a permit soon after the incident in order to damage government property, start some fires, and obstruct public passages and to allow all of this without reacting to what demonstrators are doing

[....] Lancaster police said they arrested eight individuals early Monday after demonstrators caused damage to the police station, a parked vehicle and a US Post Office building. Demonstrators also piled street signs, trash cans and other items into an intersection, at one point starting a dumpster fire, according to police.

Those arrested received charges including arson, institutional vandalism, riot, failure to disperse and obstructing highways and other public passages, police said.

Detectives are reviewing several hours of online video as well as surveillance in an effort to identify additional suspects, police later said.

Lancaster police said that more than 100 protesters had gathered on an access ramp outside the police station. Police also said they used a "public address system to provide several warnings that if the group did not move from the ramp that chemical munitions would be deployed." The department said the group failed to follow instructions and that officers used chemical agents and pepper spray to disperse the crowd [....]

from CNN

Strikes me that this is similar to the Catholic idea of penance, you know? Catholics also used to have indulgences for sale, might benefit activists to look into that idea as well.

Just forget that nonviolent theory thing, not an answer, doesn't allow any symbolic tit for tat. The responsible government has to accept some immediate suffering somehow or it's not resolved. Maybe even the community at large must do the same.