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+# Dispatch & SDK patch
+
+Rewrites client URLs to a chosen HTTP or HTTPS server. The server is a
+host or IP with an optional port, without scheme or path.
+
+## URL rules (`dispatch/mod.rs`)
+
+- `dispatch` replaces the `"DispatchUrls": [...]` list with
+  `"<origin>/query_dispatch"` entries inside its original byte range,
+  space-padding the rest.
+- `sdk` rewrites the URLs of the production `bh3_*` records in
+  `server_pc` (`env` `0` for `bh3_cn`, else `2`), padding each record to
+  its original length.
+- `android_urls` rewrites `http(s)`/`ws(s)` URLs and bare hosts on the
+  official domains (`bh3.com`, `honkaiimpact3.com`, `mihoyo.com`,
+  `hoyoverse.com`, plus one known IP). Shorter replacements keep the
+  original length with an `x…@` userinfo prefix; `ws`/`wss` follow the
+  chosen scheme.
+
+If a replacement is longer than the original, `dispatch_grow`, `sdk_grow`
+or `android_urls_grow` writes it at full length and the asset is
+enlarged: `unity::replace_script` rewrites the serialized object table and
+header size, and `Bundle::replace_node` re-chunks a UnityFS node and
+fixes its directory. The tool then prints a warning that assets were
+enlarged.
+
+## Windows (`dispatch/windows.rs`)
+
+Writes three files together and rolls back on failure:
+
+| File | Content patched |
+| --- | --- |
+| `BH3_Data/sharedassets0.assets` | `ChannelConfig` dispatch URLs; also identifies the region |
+| `BH3_Data/resources.assets` | `server_pc` SDK URLs |
+| `BH3_Data/StreamingAssets/MiHoYoSDKRes/PC/mihoyo_sdk_res` | the `server_pc` copy inside the SDK bundle |
+
+Both `server_pc` copies must be byte-equal before patching.
+
+## Android (`dispatch/android.rs`)
+
+Patches serialized files, UnityFS bundle nodes and plain text among the
+candidate `assets/` entries (`assets/bin/data/*` and known text
+extensions, except `package_config.json`, `share_config.json`, `.wmv`
+and `.bak`). `.splitN` parts are joined for patching and re-split at the
+original chunk size; enlarging can add parts. DEX, native libraries and
+`.wmv` are copied unchanged, except for the CN passport URL below. At
+least one `ChannelConfig` and one SDK/resource URL are required, otherwise
+no APK is written. The result is repacked and signed by `android::sign`.
+
+## CN passport URL (`dispatch/cn_android.rs`)
+
+The CN passport login URL is a plaintext string in the DEX that declares
+`…account.sdk.utils.RSAUtils`; only that DEX is edited. The server must
+use **HTTP** — HTTPS is rejected.
+
+The stock DEX has exactly one loopback string, `http://127.0.0.1` (an SDK
+default), between known neighbors in the sorted `string_ids` table. The
+patch:
+
+1. Appends a `string_data_item` for the chosen origin
+   (`format::dex::append_string`) and points the loopback string id at
+   it.
+2. Points the `const-string` that loaded the official login URL
+   (`https://passport-api.mihoyo.com`) at that id, so login goes to the
+   server.
+3. Moves the original loopback `const-string` to the neighboring id to
+   keep `string_ids` sorted.
+
+The origin must sort between those neighbors; other addresses are
+rejected. Checksums are recomputed.