Fix CPU metric spike on first observation #1706
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This was referenced Jan 14, 2026
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The CPU samplers (both cgroup v2 and procfs) were initializing prev stats to zeros, causing the first delta calculation to be (cumulative_since_container_start - 0) which produces an enormous spike in total_cpu_usage_millicores. Fix by making prev an Option<Stats>. On first poll, we record baseline stats but skip metric emission. Subsequent polls compute proper deltas. Changes: - cgroup/v2/cpu: Make prev Option<Stats>, skip first poll emission - procfs/stat: Make prev Option<Stats>, skip first poll emission Ports commits 5d51345 and 706bc95 from sopell/expose-observer-public to the extracted lading-observer crate. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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