Fix fighter/bomber AI remaining stationary if engines repaired

code/ai/ai_flags.h

@@ -195,6 +195,7 @@ namespace AI {
 		Fix_big_ship_waypoint_completion,	// a) big ships complete a waypoint within their radius rather than sqrt(radius);
 											// b) completion no longer requires moving 0.1m in a single frame (framerate-dependent)
 		Fix_shockwave_expire_before_do_damage,	// shockwaves whose lifetime is shorter than one frame apply their area damage at least once before expiring
+		Fix_small_ai_recover_after_engines_repaired, // ensure small ship AI can switch back to useful AI modes if engines get repaired
 
 		NUM_VALUES
 	};

code/ai/ai_profiles.cpp

@@ -755,6 +755,7 @@ void parse_ai_profiles_tbl(const char *filename)
 
 				set_flag(profile, "$fix shockwave expiring before dealing damage:", AI::Profile_Flags::Fix_shockwave_expire_before_do_damage);
 
+				set_flag(profile, "$fix fighter/bomber AI recovers after engines repaired:", AI::Profile_Flags::Fix_small_ai_recover_after_engines_repaired);
 
 				// end of options ----------------------------------------
 
@@ -985,5 +986,6 @@ void ai_profile_t::reset()
 		flags.set(AI::Profile_Flags::Kamikaze_no_collision_avoidance);
 		flags.set(AI::Profile_Flags::Fix_big_ship_waypoint_completion);
 		flags.set(AI::Profile_Flags::Fix_shockwave_expire_before_do_damage);
+		flags.set(AI::Profile_Flags::Fix_small_ai_recover_after_engines_repaired);
 	}
 }

code/ai/aicode.cpp

@@ -12447,6 +12447,13 @@ void ai_process_subobjects(int objnum)
 				}
 			}
 		}
+	} 	
+	// Goober5000 and wookieejedi - conversely, if the engines are no longer blown (e.g. after repair), resume normal chase behavior.
+	// The rest of the AI assumes SM_ATTACK_FOREVER implies blown engines, 
+	// so don't leave the submode set after the engines recover, or the ship will never evade and will ignore being hit.
+	else if (The_mission.ai_profile->flags[AI::Profile_Flags::Fix_small_ai_recover_after_engines_repaired] && ((aip->mode == AIM_CHASE) && (aip->submode == SM_ATTACK_FOREVER))) {
+		aip->submode = SM_ATTACK;
+		aip->submode_start_time = Missiontime;
 	}
 }