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tests/TC123-long-filename.md

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+# Test Case: 255-byte Filename
+
+**Test ID**: TC123-long-filename  
+**Category**: Boundary & Stress  
+**Priority**: Medium  
+**Regression**: None
+
+## Objective
+
+Verify exact `NAME_MAX` lookup, readdir name bytes, stat, and file content.
+
+## Preconditions
+
+- Complete `G7-MANUAL-SETUP.md`.
+- Use the fixture's ASCII `LONG-NAME`; its byte count must be 255.
+
+## Manual Steps
+
+```sh
+G7=/root/repo22-g7
+FIX=$G7/fixtures
+SRCROOT=$FIX/sources/boundaries
+IMAGE=$FIX/images/boundaries.erofs
+MNT=/mnt/repo22-g7-tc123
+E=$G7/evidence/TC123
+mkdir -p "$MNT" "$E"
+long_name=$(cat "$FIX/LONG-NAME")
+name_bytes=$(printf '%s' "$long_name" | wc -c | tr -d ' ')
+printf 'name_bytes=%s\nname=%s\n' "$name_bytes" "$long_name" \
+  | tee "$E/name.txt"
+test "$name_bytes" -eq 255
+unit=$(mdconfig -a -t vnode -f "$IMAGE")
+mount -t erofs -o ro "/dev/$unit" "$MNT"
+(cd "$SRCROOT" && find longname -type f -print | sort) > "$E/source.names"
+(cd "$MNT" && find longname -type f -print | sort) > "$E/target.names"
+cmp "$E/source.names" "$E/target.names"
+test "$(wc -l < "$E/target.names" | tr -d ' ')" -eq 1
+stat -f 'size=%z name=%N' "$MNT/longname/$long_name" | tee "$E/stat.txt"
+cmp "$SRCROOT/longname/$long_name" "$MNT/longname/$long_name"
+source_hash=$(sha256 -q "$SRCROOT/longname/$long_name")
+target_hash=$(sha256 -q "$MNT/longname/$long_name")
+printf 'source=%s\ntarget=%s\n' "$source_hash" "$target_hash" \
+  | tee "$E/hashes.txt"
+test "$source_hash" = "$target_hash"
+umount "$MNT"
+mdconfig -d -u "${unit#md}"
+test -z "$(mount -p | awk -v m="$MNT" '$2 == m { print }')"
+test -z "$(mdconfig -l | tr ' ' '\n' | grep -x "$unit")"
+```
+
+## PASS Gate
+
+- The filename is exactly 255 bytes and readdir returns that one exact name.
+- Stat succeeds; source/mount `cmp` and SHA256 values match.
+- No truncation, extra entry, panic, hang, or cleanup leak occurs.