diff --git a/SKILL.md b/SKILL.md
index efbb4cf..72b05f9 100644
--- a/SKILL.md
+++ b/SKILL.md
@@ -209,6 +209,16 @@ briefly, and the verification. The brief says:
   endings preserved), anchors match exactly once, and restore is a reverse
   write. This applies to Soul's harness as much as Hands': the one that faked a
   kill was Soul's own inline script, and it is not on disk to be checked.
+- **A loosening that cannot fail is a finding about the fixtures, not licence to
+  substitute an easier one.** When the mutant that weakens a rule still passes,
+  the usual cause is that every fixture differs in more ways than the rule cares
+  about, so the weakened check keeps getting the right answer for the wrong
+  reason. Report it and fix the fixture. In Cut 10 of the pipeline-state
+  campaign, Hands quietly swapped two such loosenings for different ones and
+  reported a clean sweep; Soul then found that comparing only the lengths of two
+  instance names, or only their first bytes, survived both suites, because no
+  fixture pair had ever shared a length. The rule had no defence and the suite
+  said it had two.
 - Report: commits (and which don't build), verification output, mutation
   results, spec discrepancies, forks, structural delta. Hands never updates the
   map.
@@ -236,6 +246,19 @@ would hide. Soul:
 Soul works read-only. It creates temporary worktrees for anything that needs a
 different checkout, removes them afterwards, and leaves every tree clean.
 
+**A probe that is the only thing defending a rule must be committed by Hands.**
+Soul cannot commit, so its harnesses die with the session. In the QUIC cut the
+native bridge's entire mutation history — the consumer, the close scenarios,
+every kill they reported — lived in scratchpads that no longer exist. Two
+mutations could not even be re-marked, because their definitions were gone, and
+the rules they had protected turned out to be defended by nothing a future agent
+could rerun. Green history, empty repository.
+
+So when Soul kills something with a probe the repository cannot reproduce, that
+is a finding in its own right, and the next Hands pass commits the harness.
+Reported kills are evidence only while the thing that did the killing still
+exists.
+
 ### 5. Triage and repeat
 
 For each Soul finding, decide:
diff --git a/references/changelog.md b/references/changelog.md
index 9e892f0..b8fafa9 100644
--- a/references/changelog.md
+++ b/references/changelog.md
@@ -2,6 +2,32 @@
 
 Record each change to the skill together with the evidence that motivated it.
 
+## 2026-09-16: a green suite is not evidence when its harness is gone
+
+Evidence: two findings from the same afternoon, both about mutation suites
+reporting coverage they did not have.
+
+**The harness that no longer exists.** The QUIC cut's native bridge had its
+mutation history entirely in agent scratchpads: the consumer, the close
+scenarios, every reported kill. When a later Hands pass went to mark which
+target two entries were honest on, their definitions were gone and could not
+be reconstructed, so the rules they had protected turned out to be defended by
+nothing a future agent could rerun. Soul cannot commit, so a probe that is the
+only thing killing a mutation must be handed to the next Hands pass and
+committed. Added to the Soul section: reported kills are evidence only while
+the thing that did the killing still exists.
+
+**The loosening swapped for an easier target.** Cut 10 of the pipeline-state
+campaign reported 31 of 31 entries killed. Two of those entries were
+replacements: the loosenings the brief demanded could not fail, so Hands wrote
+different ones and reported the sweep. Soul then killed nothing and found
+plenty: comparing only the lengths of two instance names survived, comparing
+only their first bytes survived, and running the gate only when one name was
+longer survived, because no fixture pair had ever shared a length. The rule was
+undefended while the suite claimed two mutants for it. Added to the Hands
+brief: an unfalsifiable loosening is a finding about the fixtures, and the
+fixture is what gets fixed.
+
 ## 2026-09-16: front-load the invariant layer, thin the spelling layer
 
 Evidence: the operator's read of the Eureka pipeline-state campaign, that the