diff --git a/tools/eureka-cut6d-mutations.psd1 b/tools/eureka-cut6d-mutations.psd1
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+# Eureka Cut 6d mutation suite: resolution history and stewardship by
+# sequence. Entries only; the harness is tools/eureka-mutations.ps1.
+#
+#   powershell -File tools/eureka-mutations.ps1 `
+#       -Entries tools/eureka-cut6d-mutations.psd1 `
+#       -Target epiphany-pipeline/src/lib.rs `
+#       -Test 'cargo test -p epiphany-pipeline --lib'
+#
+# Each entry restores the permissiveness the shape it pins removed: M23 and
+# M24 restore the one-per-subject and one-per-repo keys this cut retired, M25
+# and M26 put the sequence anywhere but last, and M27 drops a nested subject's
+# own sequence on the way into the key. Cut 6b's M2 already covers the
+# subject's kind on the same line and is re-anchored there, not repeated here.
+#
+# Stated limits, so a later reader does not mistake silence for coverage. The
+# `n` marker itself has no entry: it is pinned only by the sample-key
+# equalities in `keys_are_derived_and_mismatch_refuses` and the two prefix
+# literals, a fixture pin like 6c's M21, and changing a marker restores no
+# permissiveness. The `u32` type has no runtime mutation. Date-invariance has
+# none of its own either: putting `assigned_on` into the stewardship key is
+# not a permissiveness the old code had, and M24's test asserts the local's
+# part count is exactly two, so a mutant that appends the date as a third part
+# dies there.
+@{
+    Mutations = @(
+        @{
+            Id   = 'M23'
+            Rule = 'A subject''s resolutions are distinct records: the sequence is in the key (Q17 B).'
+            Test = 'tests::a_subject_keeps_every_resolution_it_had'
+            Old  = '            let parts = std::iter::once(value.subject.kind.name()).chain(subject_local.split(''.'')).chain(std::iter::once(sequence.as_str())).collect::<Vec<_>>();'
+            New  = '            let parts = std::iter::once(value.subject.kind.name()).chain(subject_local.split(''.'')).collect::<Vec<_>>();'
+        },
+        @{
+            Id   = 'M24'
+            Rule = 'A repo''s stewardships on a mind are distinct records: the sequence is in the key (Q18 A, Q20 A).'
+            Test = 'tests::a_repo_keeps_every_stewardship_it_had'
+            Old  = 'local(&key_field, &[&key_segment(&value.repo.0), &sequence])?)'
+            New  = 'local(&key_field, &[&key_segment(&value.repo.0)])?)'
+        },
+        @{
+            Id   = 'M25'
+            Rule = 'A stewardship''s sequence is the last part, so a repo''s assignments share a prefix (D2).'
+            Test = 'tests::a_repo_keeps_every_stewardship_it_had'
+            Old  = 'local(&key_field, &[&key_segment(&value.repo.0), &sequence])?)'
+            New  = 'local(&key_field, &[&sequence, &key_segment(&value.repo.0)])?)'
+        },
+        @{
+            Id   = 'M26'
+            Rule = 'A resolution''s sequence is the last part, so a subject''s resolutions share a prefix (D2).'
+            Test = 'tests::a_subjects_resolutions_share_a_prefix_no_other_key_has'
+            Old  = '            let parts = std::iter::once(value.subject.kind.name()).chain(subject_local.split(''.'')).chain(std::iter::once(sequence.as_str())).collect::<Vec<_>>();'
+            New  = '            let parts = std::iter::once(value.subject.kind.name()).chain(std::iter::once(sequence.as_str())).chain(subject_local.split(''.'')).collect::<Vec<_>>();'
+        },
+        @{
+            Id   = 'M27'
+            Rule = 'A nested subject is recovered whole: a resolution of a resolution keys the inner key, sequence included (defect 3, under the new shape).'
+            Test = 'tests::a_resolution_of_a_resolution_reads_back'
+            Old  = '            let parts = std::iter::once(value.subject.kind.name()).chain(subject_local.split(''.'')).chain(std::iter::once(sequence.as_str())).collect::<Vec<_>>();'
+            New  = '            let parts = std::iter::once(value.subject.kind.name()).chain(subject_local.rsplit_once(''.'').map_or(subject_local, |(head, _)| head).split(''.'')).chain(std::iter::once(sequence.as_str())).collect::<Vec<_>>();'
+        }
+    )
+}