NavHarness is a training-free harness for lifelong embodied navigation that folds memory processing (maps, task records, house knowledge, verified against new observations) into the agent loop and carries experience across fresh sessions. On GOAT-Bench it adds 18.6 (Astra) and 22.6 (Opus 5) s-SR points over context-only sessions; with SLAM poses and GPT-6 Astra it reaches a state-of-the-art 83.7 s-SR on GOAT-Bench and 85.9 on IR2R-CE. Structured recovery handovers beat length-matched summaries.