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c7499cf8fc
When a client deselects an IPv4 exit node, the auto-generated IPv6 default route (::/0) was still selected and pushed onto the tunnel interface, even though the user disabled the exit node. On an exit node without a real IPv6 egress this blackholes IPv6 traffic, and because clients prefer IPv6 (happy eyeballs) it can break general connectivity. Root cause: the synthesized v6 route gets a different NetID than its v4 base (base + "-v6"). The route selector keys deselects by NetID and defaults unknown NetIDs to selected, so the "-v6" entry was never matched by the v4 deselect. The effectiveNetID() mirror that solves exactly this is used by HasUserSelectionForRoute and FilterSelectedExitNodes, but categorizeUserSelection called the raw IsSelected(), bypassing it and mis-categorizing the v6 pair as user-selected. Add RouteSelector.IsSelectedForExitNode(), which applies effectiveNetID before the selection check, and use it in categorizeUserSelection. IsSelected() is left untouched so non-exit code paths don't make unrelated "*-v6" routes inherit v4 state. Adds regression tests for the v4/v6 deselect mirror and explicit-v6 override.