---
name: parent-chain-attribution-must-walk-to-a-root
description: "Attributing a cargo/rustc process by its IMMEDIATE parent reads every CI build as user-shell contention — rustup.exe is the shim both reach cargo through; walk the chain to a root you recognize and report that root."
metadata:
  type: feedback
---

Measured 2026-09-08, v0.68.0 golden r1, hfenduleam. I censused cargo/rustc during
`twohost-a` and reported to the gater: "NONE is rooted at Runner.Worker/RunnerService,
so none is a CI axis — these are real contention." I had walked **one** level. The
real chain was `cargo 28220 > rustup 25556 > pwsh > Runner.Worker.exe >
Runner.Listener > RunnerService` — the runner's OWN build, which I reported back as
contention against itself, complete with an overlap window starting at its start time.

**Why one level cannot work:** `rustup.exe` is the shim a CI step AND a human shell
both reach cargo through. A census that stops at the immediate parent therefore
cannot distinguish them **by construction** — it will label every CI build a user
shell and produce a confident wrong answer, not a fuzzy one. The runbook says
attribute "by parent chain"; a chain is not a parent.

**Do:** walk parents until you hit a root you recognize (`RunnerService` /
`Runner.Listener` / `Runner.Worker` = an already-counted CI axis; `bash`/`pwsh` under
a user session = real contention), and **report the root you reached** so the reader
can see the walk terminated. Six levels was enough here.

**The blast radius is a peer's ledger.** The gater was mid-recall of two agents'
builds and weighing whether a twohost red would be load-tainted; my list added a
fabricated overlap start. What saved it was the gater running his own census — not
anything in my message. State which facts survive a correction and which do not,
explicitly, because a corrected message is read by someone deciding what to keep.

Kin: [[never-send-a-claim-composed-before-its-check-ran]],
[[a-fail-prefixed-grep-drops-fail-plus-leak-rows]] — all three are a narrow
instrument reported as if it measured the wide thing.