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tests/TC086-lz4-sequential-read.md

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+# Test Case: LZ4 Sequential Read Correctness
+
+**Test ID**: TC086-lz4-sequential-read
+
+**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**: High
+
+## Objective
+
+Verify complete sequential reads of an LZ4-compressed file with two request
+sizes against the original source bytes. Record timings only; repo22 exposes no
+filesystem-specific DTrace provider and this test has no fixed throughput
+threshold.
+
+## Fixture
+
+```sh
+work=$(mktemp -d /tmp/repo22-tc086.XXXXXX)
+tests/prepare_error_fixtures.sh "$work/fixtures"
+dump.erofs -s "$work/fixtures/valid-lz4.erofs"
+dump.erofs --path=/compressed.bin -e "$work/fixtures/valid-lz4.erofs"
+```
+
+The dump must identify `/compressed.bin` as compressed LZ4 data with real
+physical extents.
+
+## FreeBSD Procedure
+
+```sh
+mkdir "$work/mnt"
+unit=$(mdconfig -a -t vnode -f "$work/fixtures/valid-lz4.erofs")
+mount -t erofs -o ro "/dev/$unit" "$work/mnt"
+
+expected=$(sha256 -q "$work/fixtures/source/compressed.bin")
+actual=$(sha256 -q "$work/mnt/compressed.bin")
+test "$actual" = "$expected"
+
+/usr/bin/time -p dd if="$work/mnt/compressed.bin" \
+  of="$work/read-4k.bin" bs=4096 2>"$work/time-4k.txt"
+cmp "$work/fixtures/source/compressed.bin" "$work/read-4k.bin"
+/usr/bin/time -p dd if="$work/mnt/compressed.bin" \
+  of="$work/read-1m.bin" bs=1048576 2>"$work/time-1m.txt"
+cmp "$work/fixtures/source/compressed.bin" "$work/read-1m.bin"
+cat "$work/time-4k.txt" "$work/time-1m.txt"
+
+umount "$work/mnt"
+mdconfig -d -u "${unit#md}"
+```
+
+## Expected Results
+
+Both complete outputs compare byte-for-byte with the source and both hashes
+match. Timing values are recorded with guest CPU, VM, and storage context; one
+buffer size is not required to outperform the other.