# FPK1 format

```
[ header ][ data blobs ][ string table ][ directory entries ]
```

## Header (28 bytes)

| Field           | Type      | Size | Offset |
|-----------------|-----------|------|--------|
| `magic`         | char[4]   | 4    | 0      |
| `entry_count`   | uint64_t  | 8    | 4      |
| `dir_offset`    | uint64_t  | 8    | 12     |
| `strtab_offset` | uint64_t  | 8    | 20     |

`magic` = `"FPK1"`.

`FPK_HEADER_SIZE` (28): field-by-field, not `sizeof()`.

## Data blobs

Raw bytes, back-to-back, no padding, writer add order.

## String table

Paths, `/`-separated, NUL-terminated, back-to-back, entry order.

`strtab_offset` points here.

## Directory (25 bytes per entry)

| Field         | Type     | Size | Offset |
|---------------|----------|------|--------|
| `path_offset` | uint64_t | 8    | 0      |
| `data_offset` | uint64_t | 8    | 8      |
| `data_size`   | uint64_t | 8    | 16     |
| `method`      | uint8_t  | 1    | 24     |

`path_offset` relative to `strtab_offset`. `data_offset` absolute.

`FPK_DIR_ENTRY_SIZE` (25): field-by-field, not `sizeof()`.

`dir_offset` points here, last region. File size = `dir_offset +
entry_count * FPK_DIR_ENTRY_SIZE`.

## Compression

`method`: reserved, v1 = `FPK_METHOD_STORE` (0) only.

## Endianness

Little-endian on disk, always. Big-endian host swaps on read/write.