ak-endfield-api-archive/MEMO.md

MEMO

This file contains my personal notes. Most of it isn't particularly useful, but it might come in handy for someone.

Regarding the Game Package Patch Update v2 Format

Although removed from the archived data, keys indicating the implementation of the v2 format appeared in the JSON data even before the v1.2.4 update.
The keys were first observed on the China channel at 2026-04-09T08:15:27.604+00:00 and on the Global channel at 2026-04-11T04:15:27.695+00:00.

Initially, the patch object contained empty data: { "v2_patch_info_url": "", "v2_patch_info_size": "0", "v2_patch_info_md5": "" }.
Upon the release of the v1.2.4 update, the official URL, size, and MD5 values began to be returned.

patch.json Specifications

Note: These are based partly on conjecture.

export interface Root {
  version: string; // e.g., 1.2.4
  vfs_base_path: string; // e.g., Endfield_Data/StreamingAssets/VFS
  files: File[];
}

export interface File {
  name: string; // e.g., C3442D43/223F9ED9DB4013D27E6FB3B78623E051.chk
  name_path: string; // ""
  md5: string; // e.g., 1ceb1c5aaf4dace09f3ec359c78f0501
  size: number; // e.g., 4516428
  diffType: 1 | 2; // 1=chk?, 2=blk?
  local_path?: string; // e.g., vfs_files/files/Endfield_Data/StreamingAssets/VFS/775A31D1/449D95744A00F33BD9C304EF1E72A534.chk
  patch?: Patch[];
}

export interface Patch {
  base_file: string; // e.g., C3442D43/47D0EB2D178F6E81EE4D0226E0806AB9.chk
  base_file_path: string; // ""
  base_md5: string; // e.g., dac0d4c6a910fb4e1000d9414cd1ee4b
  base_size: number; // e.g., 4518476
  patch: string; // e.g., diff_1.2.4_1.1.9/C3442D43_223F9ED9DB4013D27E6FB3B78623E051.chk_patch
  patch_path: string; // ""
  patch_size: number; // e.g., 136568
}

• If local_path does not exist and patch does not exist: No action is taken.
• If local_path exists and patch does not exist (Incremental): A new file exists. Copy the file located at local_path within the patch data to ${vfs_base_path}/${files[number].name}.
• If local_path does not exist and patch exists (Differential): A difference exists. Using ${vfs_base_path}/${files[number].base_file} as the source file, apply the patch found at vfs_files/vfs_patch/${files[number].patch[number].patch} in the patch data and write the result to ${vfs_base_path}/${files[number].name}. HDiffPatch is used for applying the differential.
• If both local_path and patch exist: This scenario is currently not possible.