Evaluated zero-shot on VLN-CE through a minimal Codex-harness interface, GPT-6-Astra navigates unfamiliar environments from monocular RGB alone, with no navigation fine-tuning, waypoint predictor, or pre-built scene map. On the common R2R-CE benchmark, its ultra-reasoning setting reaches 79.0% success, beating the strongest reported zero-shot and supervised results by 13.0 and 6.9 points respectively, and it handles multi-stage instructions by grounding spatial relations and tracking progress. Reliable route execution and goal verification remain weak even with heavy reasoning, since plausible local landmark matches don't reliably imply correct task completion.