diff --git a/tests/fixtures/competency/unrelated-edit-preservation/SCENARIO.md b/tests/fixtures/competency/unrelated-edit-preservation/SCENARIO.md
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+# Unrelated edit preserves valid understanding
+
+Procedure: reconstruct `checkout_total`, then edit only `unrelated.py`.
+
+Expected: the checkout claim/task identity remains reusable and established; the unrelated edit must not demote it or force reinvestigation.
diff --git a/tests/fixtures/competency/unrelated-edit-preservation/feature.py b/tests/fixtures/competency/unrelated-edit-preservation/feature.py
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+++ b/tests/fixtures/competency/unrelated-edit-preservation/feature.py
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+def checkout_total(items):
+    return sum(item['price'] for item in items)
diff --git a/tests/fixtures/competency/unrelated-edit-preservation/unrelated.py b/tests/fixtures/competency/unrelated-edit-preservation/unrelated.py
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+++ b/tests/fixtures/competency/unrelated-edit-preservation/unrelated.py
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+BANNER_TEXT = 'Welcome'