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tests/TC051-namecache-hit.md

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+# Test Case: Repeated Positive Lookup Behavior
+
+**Test ID**: TC051-namecache-hit
+**Category**: VFS Integration
+**Priority**: High
+
+## Objective
+
+Verify repeated positive pathname lookups remain stable within one mount.
+This is behavior-level namecache integration coverage; timing differences do
+not prove an internal cache hit.
+
+## Procedure
+
+Mount vfs/vfs-plain.erofs and run:
+
+    stat -f 'ino=%i mode=%p size=%z gen=%v' \
+      /tmp/repo22-g3/mnt/testdir/file.txt > TC051-first.txt
+    stat -f 'ino=%i mode=%p size=%z gen=%v' \
+      /tmp/repo22-g3/mnt/testdir/file.txt > TC051-second.txt
+    cmp TC051-first.txt TC051-second.txt
+    cmp fixtures/vfs/source/testdir/file.txt \
+      /tmp/repo22-g3/mnt/testdir/file.txt
+
+## Expected Results
+
+Both lookups succeed with byte-identical metadata and data. Record only this
+observable behavior as PASS; do not claim a measured cache hit without kernel
+instrumentation. Record output and cleanup.