A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 11 October 2012
Say I use a range attack on someone in an ambush battle while I have it reconed with the stronghold. I don't kill them, but reduce the force by the range attacks strength. If that personality lives will he still have the force penalty or does it only last until the end of the battle.
Koshin Keep Recon Reaction: After engaging: You have Reconnaissance at the current battlefield. Until this battle ends, your Ranged Attacks that do not destroy their target have the additional effects, "reduce the target's Force by the Ranged Attack's strength and you may take an additional Ranged Attack Battle action that may only target the same card".
The bold text made my friend argue the force penalty was just for the battle.
Jon Palmer (rules official), 12 October 2012
Say I use a range attack on someone in an ambush battle while I have it reconed with the stronghold. I don't kill them, but reduce the force by the range attacks strength. If that personality lives will he still have the force penalty or does it only last until the end of the battle.
Koshin Keep Recon Reaction: After engaging: You have Reconnaissance at the current battlefield. Until this battle ends, your Ranged Attacks that do not destroy their target have the additional effects, "reduce the target's Force by the Ranged Attack's strength and you may take an additional Ranged Attack Battle action that may only target the same card".
The bold text made my friend argue the force penalty was just for the battle.
The force penalty on Koshin Keep does not list the duration, so therefore by default it is until the end of the turn.