05cc026d75
The picker blocks on user input for however long they take. In that window niri can destroy a dynamic workspace (its last window closed) and renumber every later one down, so the pre-pick current["idx"] can point at the wrong workspace by the time move-window-to-workspace runs — restoring to the wrong place. The stashed window itself can also have closed in the meantime, in which case the move/focus calls would silently no-op. main() now re-reads workspaces/windows after pick() returns, recomputes the current workspace, and confirms the chosen window still exists before acting; each bails with a notify and the documented exit code otherwise. Adds window_exists() as a pure, tested helper alongside the existing pure functions. Also: clarify the focus=false comment in niri/config.kdl (it read as if focus=false caused the problem it actually prevents), and note in the design doc's Out of scope section that the stash's index-1 pinning is per-output, so a second monitor would need its own analysis of the Mod+1..9 offset.