# How Unlocked Restrictions works

## How copying works

Telegram refuses to forward protected content, and also to re-send its media by file id, so a
copy is sent the same way as a message you wrote:

- text keeps its formatting; photos, videos, files, voice messages and GIFs are downloaded
  (or taken from the local cache) and uploaded again; stickers, locations and contacts are sent
  directly;
- albums are sent as media groups again (at most 10 items per group);
- bot-only parts are dropped: reply and inline keyboards, games, invoices; content that can't
  be reproduced (polls, dice, stories, giveaways, paid media) is skipped, and only its text is
  sent if there is any;
- the selection is sent once every item is ready, so one large download delays the batch;
- items that can't be copied are reported in a bulletin.

Copied videos have no preview thumbnail. The lock covers groups and channels, not private chats
where the other person enabled content protection.

## Runtime notes

Things the on-device runtime does differently from the SDK docs, all handled in `src/`:

- Java lists are not iterable from Python; use `hooking.java_list()`.
- `param.setResult()` in a before-hook does not skip the original method, so the forward hook
  empties the message list instead.
- `threading.local` state is not shared between a before-hook and its after-hook.
- Java `String` values arrive as Python `str`, other `CharSequence`s as Java objects.
- Fields named like `java.lang.Object` methods (`SendMessageParams.notify`) must be set with
  `hook_utils.set_private_field`.
- Exceptions escaping a Python thread vanish silently, so the copy worker catches everything.
- Shared TL objects (`TLRPC.Chat` and friends) are never modified for display purposes.