When importing issues in a multi-rig setup (Gas Town), the prefix validation was failing for issues with prefixes from other rigs (e.g., hq-* prefixes from town-level beads). This fix extends buildAllowedPrefixSet to also load prefixes from routes.jsonl, allowing issues from any routed rig to pass validation. Fixes: gt-2maz79 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>