activeTrace

The distributed-trace context resolved at the synchronous capture edge, on the caller that logged — never on the drain coroutine (#1034). The edge fills this by calling LogCapture.resolveAtEdge while it still sees the caller's ambient context; LogCapture.capture then feeds the sampling gate from this snapshot instead of re-consulting the provider off-thread.

null means either no provider is wired (the M1 always-on default) or the provider resolved to "untraced" — the two are disambiguated by whether a TraceContextProvider was installed, which LogCapture.capture knows.