=== Task 1 deep dive: residency attribution (7-year GER40 window) ===
VmHWM at start = 6 MiB

(B) 4 raw sources, NO harness/sinks:
    streamed 8634128 records, peak resident_records/source = 1024
    VmHWM after = 125 MiB

(A) full breakout harness + 4 recorder taps + drain_trace:
    trace rows = 148688
    VmHWM after = 210 MiB

VmHWM final = 210 MiB
