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Johnathan Corgan
2bc0345174
cost-avoidance and mixed-technology decide a parent by measured link cost (etx * (1 + srtt_ms/100)). Under the local CI's 4-way-parallel chaos the fast fiber link's measured srtt spikes from host scheduling and can exceed the Bluetooth link's, flipping the choice and reddening a run that proves nothing about the daemon. The old margin was ~0.4 cost units, which a ~24ms one-sided scheduling blip closes. Widen the Bluetooth delay to 150-250ms so the margin dwarfs any plausible one-sided spike. The link still establishes well within the handshake budget (a ~500ms RTT against a 30s stale-handshake window), so the losing candidate is still a real, established peer rather than an absent one. Add a netem mutation exclude_edges option and use it in mixed-technology to pin the two links n08 chooses between, so a random degradation can't flip the asserted comparison either. An unknown excluded edge is a hard error, since a silent no-op would reintroduce the flakiness it exists to remove. Validated by running both scenarios repeatedly under heavier-than-CI concurrent load: the parent choice holds every time.