---
name: non-vacuity-check-can-fail-for-the-defects-reason
description: "A non-vacuity check that the defect can also break must be COLLECTED into the verdict, not asserted in front of it — otherwise the defect reports as a broken rig."
metadata: 
  node_type: memory
  type: feedback
  originSessionId: 8900f927-ebfd-4dad-9e0e-7cec916dcda8
  modified: 2026-08-04T14:44:37.905Z
---

A control/non-vacuity assertion ("the rig produced the thing at all") placed BEFORE the
invariant assertions will, on the defect-carrying tree, fire first and read as **my rig is
broken** — hiding the whole defect shape behind one misleading line.

Measured 2026-08-04, F2 seam for REQ-ER-GRANT-ANNOUNCE-AFTER-ATTACH. Non-vacuity: "a
confirmed seat leaves exactly one empowerment record". At the pre-fix sha the seated arm
ended with **ZERO** — a grant written at admit time is keyed on the session the harness
binds, and the seat that follows classifies as a control EDGE
(`classify_control_edge(None, Some(gen)) == Dropped`) which revokes it. So the pre-fix
shape does not merely announce too soon; it leaves the operator TOLD they hold the subnet
while holding nothing. Asserted up front, that would have printed as a rig failure.
Collected into a `Vec<String>` of violations with one final assert, the run printed the
complete 7-violation signature in ONE pass.

**Why:** the reason a non-vacuity check exists (proving the rig can produce the artifact)
and the reason it can fail (the defect destroys the artifact) are indistinguishable from
the assertion itself. Only the verdict's shape decides which story the reader gets.

**How to apply:** before ordering assertions, ask of every precondition/control check —
*can the defect under test make this false?* If yes it is not a precondition, it is a
finding: collect it. Keep as immediate asserts only what the defect cannot touch (the arms
admitted, the ticket minted, the seat taken). Collect the invariant halves too, so one run
reports the whole shape — a test that stops at the first failing surface makes a defect
that hits six surfaces look like one that hits one, and the reader then fixes the surface
instead of the seam. Kin [[rig-inherits-the-defect-it-studies]],
[[make-a-new-rig-red-on-purpose]], [[intermittent-green-is-zero-information]].