* Add silent column to mentions

* Save silent mentions in ActivityPub Create handler and optimize it

Move networking calls out of the database transaction

* Add "limited" visibility level masked as "private" in the API

Unlike DMs, limited statuses are pushed into home feeds. The access
control rules between direct and limited statuses is almost the same,
except for counter and conversation logic

* Ensure silent column is non-null, add spec

* Ensure filters don't check silent mentions for blocks/mutes

As those are "this person is also allowed to see" rather than "this
person is involved", therefore does not warrant filtering

* Clean up code

* Use Status#active_mentions to limit returned mentions

* Fix code style issues

* Use Status#active_mentions in Notification

And remove stream_entry eager-loading from Notification

* Downcase signed_headers string before building the signed string

The HTTP Signatures draft does not mandate the “headers” field to be downcased,
but mandates the header field names to be downcased in the signed string, which
means that prior to this patch, Mastodon could fail to process signatures from
some compliant clients. It also means that it would not actually check the
Digest of non-compliant clients that wouldn't use a lowercased Digest field
name.

Thankfully, I don't know of any such client.

* Revert "Remove dead code (#8919)"

This reverts commit a00ce8c9.

* Restore time window checking, change it to 12 hours

By checking the Date header, we can prevent replaying old vulnerable
signatures. The focus is to prevent replaying old vulnerable requests
from software that has been fixed in the meantime, so a somewhat long
window should be fine and accounts for timezone misconfiguration.

* Escape users' URLs when formatting them

Fixes possible HTML injection

* Escape all string interpolations in Formatter class

Slightly improve performance by reducing class allocations
from repeated Formatter#encode calls

* Fix code style issues

Regression from #8951

Mention and emoji code may perform network calls, but does not need
to do that inside the database transaction. This may improve availability
of database connections when using pgBouncer in transaction mode.

* Add conversations API

* Add web UI for conversations

* Add test for conversations API

* Add tests for ConversationAccount

* Improve web UI

* Rename ConversationAccount to AccountConversation

* Remove conversations on block and mute

* Change last_status_id to be a denormalization of status_ids

* Add optimistic locking

* Force use language detector if account is remote

* Set unknown remote toot's language as nil

* Changed list behaviour

I added the following line to the FeedManager (app/lib/feed_manager.rb) in the push_to_list function:

`return false if status.reply?`

Now all posts that are replies are filtered out, so that now only "genuine" posts are displayed in the list.

This is a first approach to solve issue #5916

* Update feed_manager.rb

As suggested by @Gargron

* Verify link ownership with rel="me"

* Add explanation about verification to UI

* Perform link verifications

* Add click-to-copy widget for verification HTML

* Redesign edit profile page

* Redesign forms

* Improve responsive design of settings pages

* Restore landing page sign-up form

* Fix typo

* Support <link> tags, add spec

* Fix links not being verified on first discovery and passive updates

Add tests to avoid similar issues in the future

Fix #8080

* Add animate custom emoji param to embed pages

* Rename param, use it for avatars and gifs

* Fix issues pointed by codeclimate and breaking test

* Ignore brakeman warning

* If an Update is signed with known key, skip re-following procedure

Because it means the remote actor did *not* lose their database

* Add CLI method for rotating keys

    bin/tootctl accounts rotate [USERNAME]

Generates a new RSA key per account and sends out an Update activity
signed with the old key.

* Key rotation: Space out Update fan-outs every 5 minutes per 1000 accounts

* Skip suspended accounts in key rotation

* rubocop: quit being so picky

* rubocop: miscellany

* rubocop: prefer present to blank

* Spread out crawling randomly to avoid DDoSing the link

Fix #4486

* Remove trailing whitespace

In the same way as contentMap and nameMap.

* Add default_settings class method to ScopedSettings

ScopedSettings was extended to use value of unscoped setting instead of
only using defaults set in config/settings.yml for selected settings.
This adds possibility for admins to set default values of users' settings,
for example default theme (as requested in #7092).

* Add ability to change an instance default theme

Closes #7092

* Fix URI not being sufficiently validated with prefetched JSON

* Add additional id validation to OStatus documents, when possible

* Add Follow#revoke_request!

* Implement Undo { Accept { Follow } } (fixes #8234)

* Fix incorrect context definition for the "featured" keyword

Fix #8077

* Adjust context definition for movedTo

Fix #7994

If the input text is blank after preparation (only mention, or
only URL, or empty as in a media post), then use nil as language,
since it's OK to show to everyone.

Otherwise, always fall back to the server's default locale

* Add option to not consider word boundaries when filtering phrases

* Add a few tests for keyword/phrase filtering

* In keyword filter, account for reblogs, HTML and whole-words

* Match whole words in JS filter, too

* Fix typo

* Re-add follow recommendations API

    GET /api/v1/suggestions

Removed in 8efa081f due to Neo4J
dependency. The algorithm uses triadic closures, takes into account
suspensions, blocks, mutes, domain blocks, excludes locked and moved
accounts, and prefers more recently updated accounts.

* Track interactions with people you don't follow

Replying to, favouriting and reblogging someone you're not following
will make them show up in follow recommendations. The interactions
have different weights:

- Replying is 1
- Favouriting is 10 (decidedly positive interaction, but private)
- Reblogging is 20

Following them, muting or blocking will remove them from the list,
obviously.

* Remove triadic closures, ensure potential friendships are trimmed

If Mastodon accesses to the hidden service via transparent proxy, it's needed to avoid checking whether it's a private address, since `.onion` is resolved to a private address.
I was previously using the `HIDDEN_SERVICE_VIA_TRANSPARENT_PROXY` to provide that function. However, I realized that using `HIDDEN_SERVICE_VIA_TRANSPARENT_PROXY` is redundant, since this specification is always used with `ALLOW_ACCESS_TO_HIDDEN_SERVICE`. Therefore, I decided to integrate the setting of `HIDDEN_SERVICE_VIA_TRANSPARENT_PROXY` into` ALLOW_ACCESS_TO_HIDDEN_SERVICE`.

* Add keyword filtering

    GET|POST       /api/v1/filters
    GET|PUT|DELETE /api/v1/filters/:id

- Irreversible filters can drop toots from home or notifications
- Other filters can hide toots through the client app
- Filters use a phrase valid in particular contexts, expiration

* Make sure expired filters don't get applied client-side

* Add missing API methods

* Remove "regex filter" from column settings

* Add tests

* Add test for FeedManager

* Add CustomFilter test

* Add UI for managing filters

* Add streaming API event to allow syncing filters

* Fix tests

* Allow selecting default posting language instead of auto-detect

* Enable default language setting in credentials API

* Fix form saving