diff --git a/AGENTS.md b/AGENTS.md
index 2de078f..f4b4d6f 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -278,10 +278,30 @@ Two helper functions in `newServer.go` handle context cancellation during stream
 - **Regular files**: streamed into tar archive with content
 - **Directories**: included as tar directory entries
 - **Symlinks**: stored as symlink entries (target path preserved). Backer never resolves or follows symlinks during directory traversal — it uses `os.Lstat` and `filepath.WalkDir` which do not follow symlinks. This means symlink cycles are impossible to occur.
+- **Broken symlinks**: archived with their target path (even if target doesn't exist)
 - **Device files** (char/block): included with correct major/minor
-- **Named pipes**: included (header only, no data)
+- **Named pipes (FIFOs)**: included (header only, no data)
 - **Sockets**: skipped (not archivable)
 - **Hard links**: deduplicated — if multiple files share the same inode, only the first is stored with content, subsequent hard links are stored as link entries pointing to the original
+- **GNU tar format**: archives use GNU tar format (`header.Format = tar.FormatGNU`) for compatibility with GNU tar utility
+
+### Archive Test Coverage
+
+All entity types are tested in `internal/backer/utils_test.go`:
+
+| Entity Type | Test Function |
+|------------|---------------|
+| Regular file | `TestCreateTarGzStreamBasic` |
+| Empty file | `TestCreateTarGzStreamEmptyFile` |
+| Directory | `TestCreateTarGzStreamDirectory` |
+| Symlink | `TestCreateTarGzStreamSymlink` |
+| Broken symlink | `TestCreateTarGzStreamBrokenSymlink` |
+| Symlink to directory | `TestCreateTarGzStreamSymlinkToDirectory` |
+| Hard link | `TestCreateTarGzStreamHardLink` |
+| Character device | `TestCreateTarGzStreamDeviceFile` (falls back to char device) |
+| Named pipe (FIFO) | `TestCreateTarGzStreamNamedPipe` |
+| Special characters in names | `TestCreateTarGzStreamSpecialCharacters` |
+| Nested files | `TestCreateTarGzStreamNestedFiles` |
 
 ### Pipe Error Recovery
 
diff --git a/llms.txt b/llms.txt
index f0cb2f1..c61b593 100644
--- a/llms.txt
+++ b/llms.txt
@@ -133,12 +133,18 @@ Skips files that can't be read (logs warning, continues backup).
 Backup filenames include timestamp and configured prefix: `backup-20060102-150405.tar.gz` (extension depends on compression_algorithm).
 
 ### Special File Types
-- **Device files** (character/block) are included with correct major/minor numbers.
-- **Sockets** are skipped (no entry created).
-- **Symlinks** are stored as symlinks (target path stored) - uses os.Lstat, no cycles possible.
-- **Named pipes** and other special files are included (tar header created).
-- **Hard links** are deduplicated - first occurrence stored with content, subsequent as link entries.
-- **Regular files** are compressed; other file types have no data section.
+- **Regular files**: streamed into tar archive with content
+- **Directories**: included as tar directory entries
+- **Symlinks**: stored as symlink entries (target path preserved) - uses os.Lstat, no cycles possible
+- **Broken symlinks**: archived with their target path (even if target doesn't exist)
+- **Device files** (char/block): included with correct major/minor numbers
+- **Named pipes (FIFOs)**: included (header only, no data)
+- **Sockets**: skipped (not archivable)
+- **Hard links**: deduplicated - first occurrence stored with content, subsequent as link entries
+- **GNU tar format**: uses `header.Format = tar.FormatGNU` for GNU tar compatibility
+
+### Test Coverage
+All entity types are tested: regular files, empty files, directories, symlinks, broken symlinks, symlinks to directories, hard links, device files, named pipes (FIFOs), special characters in filenames.
 
 ### Error Recovery
 - `writeWithContext` checks context before calling fn.