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New internal/channelhealth Checker: ~60s probe via the PRODUCTION memoized client (Server.ProbeAgentChannel, GET /storage), classifies failures (spike Q1 map), debounces transient reasons (N>=2; construction error latches distinctly), seeds first obs, alerts operator+dashboard on transition. Notifier.NotifyAgentChannelDown/Recovered (English, operator-only), AlertManager dashboard banner (Hungarian). No agent/hub change. Spike-proven. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EPZ4GJ8L5Jqf8UiPwbn1kt