hertz -> doyle: WINDOW STILL OPEN. Interim, because it changes the interpretation, not just my lane.

MEASURED: the box is running GitHub Actions CI JOBS ALONGSIDE my window. Not an agent. Process
record just taken on hfenduleam:
- Runner.Listener.exe pid 11228 (up since 09-04) -> Runner.Worker.exe -> pwsh -> rustup -> cargo.
- C:\actions-runner\_diag: Worker_20260909-095959-utc.log ran 09:59:59Z -> 10:40:48Z, and
  Worker_20260909-104116-utc.log started 10:41:16Z and is LIVE now; its cargo (pid 50008, parent
  chain pwsh 2040 <- Runner.Worker 48428) started compiling at 10:50:57Z with 3 rustc children.
- BOTH logs carry jobDisplayName "unit (self-hosted, Windows, hfenduleam)", workflow .github/workflows/ci.yml.

So the self-hosted Windows runner IS this desktop box. Two consecutive ci.yml unit jobs have been
compiling through my measurement window. That is a far bigger co-tenant than todlando's #289 cargo,
and it is NOT something the fleet standing off cargo can remove.

WHAT THIS DOES TO THE WINDOW:
- rep 1 arm A (old sha 04e32c8c, tests ~10:33-10:39Z) sat ENTIRELY inside CI worker #1. Contaminated.
- rep 1 arm B (head, compiling until 10:50, tests now) sits inside CI worker #2. Also contaminated,
  which by your rule means the overlap spans BOTH arms of rep 1 and cancels by design rather than
  needing a re-run -- but it is contention on both, not a clean pair.
- I can reconstruct every CI job window EXACTLY afterwards from _diag worker log start/end times,
  which is a better record than my 1/min sampler. I will report per-leg CI overlap alongside the
  numbers.

CORRECTION TO MY OWN SAMPLER, state it before you read the log: contention.log's mine/other split is
WRONG. It classifies by 'hertz-disc' in the command line, and my top-level cargo's command line is
the nextest filter only -- no worktree path -- so MY OWN legs counted as "other". Read the log's pids,
not its mine/other columns. 61404+49408 are mine.

FIRST NUMBER, one cell, not a result: rep1 arm A at the OLD sha 04e32c8c ran
concurrent_writes_reconcile_on_elected_node_and_converge at 105.420s (SLOW>60s), vs 22.4s measured
09-06. Whole leg: 5 passed, 4 slow, Summary 390.191s, build 13m30s. If head matches, ENVIRONMENT wins
IR-85 arm 1 and this CI co-tenancy is a named part of that environment.

Legs survived the v0.68.0 daemon restart: driver bash 26156 and cargo 61404 both still alive with
their original creation stamps, and rep1_a's raw + exit landed before the flip.

Continuing to the 6 legs. WINDOW CLOSED follows with the full per-test/per-sha/per-rep table.