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+# Test Case: LZ4 ztailpacking Edge Cases
+
+**Test ID**: TC092-ztailpacking-edge  
+
+**G5 fixture contract**: Use [G5-MANUAL-SETUP.md](G5-MANUAL-SETUP.md).
+Its generated paths, source comparisons, structured corruption offsets, and
+cleanup rules supersede placeholder examples in this file.
+**Category**: Compression  
+**Priority**: Medium  
+**Regression**: None
+
+## Objective
+Verify correct handling of edge cases in ztailpacking (compressed tail packing) feature.
+
+## Preconditions
+- Generated image: `images/lz4-ztail.erofs`
+- Test files:
+  - `/exact-pcluster.dat` (4096-byte non-tail control)
+  - `/one-byte-tail.dat` (4097-byte logical boundary case)
+  - `/max-tail.dat` (8191-byte logical boundary case)
+  - `/zero-tail.dat` (empty-file control)
+- `/inline.dat` is independently proven by the manifest to have
+  `Z_EROFS_ADVISE_INLINE_PCLUSTER` and nonzero `h_idata_size`. The four edge
+  controls must not be described as ztailpacked unless their own map headers
+  prove it.
+- Mount point: `/mnt/test`
+
+## Test Steps
+1. Mount the image:
+   ```
+   mount -t erofs /dev/md0 /mnt/test
+   ```
+
+2. Read file with exact pcluster size (no tail):
+   ```
+   cat /mnt/test/files/exact-pcluster.dat > /tmp/out1
+   sha256sum /tmp/out1
+   ```
+
+3. Read file with minimal tail (1 byte):
+   ```
+   cat /mnt/test/files/one-byte-tail.dat > /tmp/out2
+   tail -c 1 /tmp/out2 | od -A n -t x1
+   ```
+
+4. Read file with maximum tail size:
+   ```
+   cat /mnt/test/files/max-tail.dat > /tmp/out3
+   stat -f %z /tmp/out3
+   ```
+
+5. Read file with zero-length tail:
+   ```
+   cat /mnt/test/files/zero-tail.dat > /tmp/out4
+   ```
+
+## Expected Results
+- Step 2: File without tail read correctly
+- Steps 2-5: Every exact logical size, full SHA256, and byte comparison matches
+  its source file
+
+## Verification Method
+- Verify all tail size edge cases handled
+- Confirm boundary conditions don't cause errors
+- Test tail packing storage limits enforced correctly
+- Verify data integrity for all edge cases
+
+## Cleanup
+```
+umount /mnt/test
+mdconfig -d -u "${unit#md}"
+rm /tmp/out*
+```
+
+## Notes
+- Tail size limits depend on inline storage capacity
+- Zero-length tail is valid edge case
+- Exact pcluster alignment means no tail needed
+- Related tests: TC091 (basic ztailpacking)