Images sent with text from WhatsApp - Text message is placed in `body` of `m.image` instead of bridged separately as an `m.notice` event.

[lasagnacrab]

Synapse Version: v1.116.0 Mautrix-WhatsApp Bridge Version: 0.11.0+dev.1f454a82 Go Version: go1.23.2

This occurs when a user sends an image and adds text to the caption field in WhatsApp prior to sending. These messages bridge with the text caption as part of the image event body and not as a separate notice event like it has been handled previously. This prevents the caption from showing up in the client, and only visible by clicking or hovering on the photo in Element, or in some clients like FluffyChat, completely invisible unless I view the source of the event to see the body of the image content where the caption is displayed.

I'm seeing this behavior in the WhatsApp bridge as well as the Google Messages bridge.

Below are the event sources and my current config if I am configuring something incorrectly.

Thanks

Event Source for current state. I shared a picture from my camera roll, added a caption, and sent through WhatsApp.

{
  "type": "m.room.message",
  "sender": "@whatsapp_phonenumber:homeserver.com",
  "content": {
    "body": "Caption text test",
    "filename": "image.jpg",
    "info": {
      "h": 1200,
      "mimetype": "image/jpeg",
      "size": 149499,
      "w": 1600
    },
    "m.mentions": {},
    "msgtype": "m.image",
    "url": "mxc://homeserver.com/url"
  },
  "origin_server_ts": originserver,
  "unsigned": {
    "membership": "join",
    "age": 750
  },
  "event_id": "$eventid",
  "room_id": "!roomid:homeserver.com"
}

Event Source in previous versions. It sends as two separate events. Image Source:

{
  "type": "m.room.message",
  "room_id": "!roomid:homeserver.com",
  "sender": "@whatsapp_phonenumber:homeserver.com",
  "content": {
    "body": "image.jpg",
    "info": {
      "h": 1600,
      "mimetype": "image/jpeg",
      "size": 214590,
      "thumbnail_info": {
        "h": 1600,
        "mimetype": "image/jpeg",
        "size": 214590,
        "w": 1200
      },
      "thumbnail_url": "mxc://homeserver.com/url",
      "w": 1200
    },
    "msgtype": "m.image",
    "url": "mxc://homeserver.com/url"
  },
  "origin_server_ts": originserver,
  "unsigned": {
    "membership": "join",
    "age": 764887404
  },
  "event_id": "$eventid_photo",
  "user_id": "@whatsapp_phonenumber:homeserver.com",
  "age": 764887404
}

Caption Source:

{
  "type": "m.room.message",
  "room_id": "!roomid:homeserver.com",
  "sender": "@whatsapp_phonenumber:homeserver.com",
  "content": {
    "msgtype": "m.notice",
    "body": "Bridged caption text",
    "m.mentions": {}
  },
  "origin_server_ts": originserver,
  "unsigned": {
    "membership": "join",
    "age": 764886514
  },
  "event_id": "$eventid_caption",
  "user_id": "@whatsapp_phonenumber:homeserver.com",
  "age": 764886514
}

My current config:

# Network-specific config options
network:
    # Device name that's shown in the "WhatsApp Web" section in the mobile app.
    os_name: Mautrix-WhatsApp bridge
    # Browser name that determines the logo shown in the mobile app.
    # Must be "unknown" for a generic icon or a valid browser name if you want a specific icon.
    # List of valid browser names: https://github.com/tulir/whatsmeow/blob/efc632c008604016ddde63bfcfca8de4e5304da9/binary/proto/def.proto#L43-L64
    browser_name: unknown

    # Proxy to use for all WhatsApp connections.
    proxy: null
    # Alternative to proxy: an HTTP endpoint that returns the proxy URL to use for WhatsApp connections.
    get_proxy_url: null
    # Whether the proxy options should only apply to the login websocket and not to authenticated connections.
    proxy_only_login: false

    # Displayname template for WhatsApp users.
    # {{.PushName}}     - nickname set by the WhatsApp user
    # {{.BusinessName}} - validated WhatsApp business name
    # {{.Phone}}        - phone number (international format)
    # {{.FullName}}     - Name you set in the contacts list
    displayname_template: "{{or .BusinessName .PushName .JID}} (WA)"

    # Should incoming calls send a message to the Matrix room?
    call_start_notices: true
    # Should another user's cryptographic identity changing send a message to Matrix?
    identity_change_notices: false
    # Send the presence as "available" to whatsapp when users start typing on a portal.
    # This works as a workaround for homeservers that do not support presence, and allows
    # users to see when the whatsapp user on the other side is typing during a conversation.
    send_presence_on_typing: false
    # Should WhatsApp status messages be bridged into a Matrix room?
    # Disabling this won't affect already created status broadcast rooms.
    enable_status_broadcast: true
    # Should sending WhatsApp status messages be allowed?
    # This can cause issues if the user has lots of contacts, so it's disabled by default.
    disable_status_broadcast_send: true
    # Should the status broadcast room be muted and moved into low priority by default?
    # This is only applied when creating the room, the user can unmute it later.
    mute_status_broadcast: true
    # Tag to apply to the status broadcast room.
    status_broadcast_tag: m.lowpriority
    # Should the bridge use thumbnails from WhatsApp?
    # They're disabled by default due to very low resolution.
    whatsapp_thumbnail: false
    # Should the bridge detect URLs in outgoing messages, ask the homeserver to generate a preview,
    # and send it to WhatsApp? URL previews can always be sent using the `com.beeper.linkpreviews`
    # key in the event content even if this is disabled.
    url_previews: false
    # Should the bridge always send "active" delivery receipts (two gray ticks on WhatsApp)
    # even if the user isn't marked as online (e.g. when presence bridging isn't enabled)?
    #
    # By default, the bridge acts like WhatsApp web, which only sends active delivery
    # receipts when it's in the foreground.
    force_active_delivery_receipts: false
    # Settings for converting animated stickers.
    animated_sticker:
        # Format to which animated stickers should be converted.
        # disable - No conversion, just unzip and send raw lottie JSON
        # png - converts to non-animated png (fastest)
        # gif - converts to animated gif
        # webm - converts to webm video, requires ffmpeg executable with vp9 codec and webm container support
        # webp - converts to animated webp, requires ffmpeg executable with webp codec/container support
        target: webp
        # Arguments for converter. All converters take width and height.
        args:
            width: 320
            height: 320
            fps: 25 # only for webm, webp and gif (2, 5, 10, 20 or 25 recommended)

    # Settings for handling history sync payloads.
    history_sync:
        # How many conversations should the bridge create after login?
        # If -1, all conversations received from history sync will be bridged.
        # Other conversations will be backfilled on demand when receiving a message.
        max_initial_conversations: -1
        # Should the bridge request a full sync from the phone when logging in?
        # This bumps the size of history syncs from 3 months to 1 year.
        request_full_sync: false
        # Configuration parameters that are sent to the phone along with the request full sync flag.
        # By default, (when the values are null or 0), the config isn't sent at all.
        full_sync_config:
            # Number of days of history to request.
            # The limit seems to be around 3 years, but using higher values doesn't break.
            days_limit: null
            # This is presumably the maximum size of the transferred history sync blob, which may affect what the phone includes in the blob.
            size_mb_limit: null
            # This is presumably the local storage quota, which may affect what the phone includes in the history sync blob.
            storage_quota_mb: null
        # Settings for media requests. If the media expired, then it will not be on the WA servers.
        # Media can always be requested by reacting with the ♻️ (recycle) emoji.
        # These settings determine if the media requests should be done automatically during or after backfill.
        media_requests:
            # Should the expired media be automatically requested from the server as part of the backfill process?
            auto_request_media: true
            # Whether to request the media immediately after the media message is backfilled ("immediate")
            # or at a specific time of the day ("local_time").
            request_method: immediate
            # If request_method is "local_time", what time should the requests be sent (in minutes after midnight)?
            request_local_time: 120
            # Maximum number of media request responses to handle in parallel per user.
            max_async_handle: 2

# Config options that affect the central bridge module.
bridge:
    # The prefix for commands. Only required in non-management rooms.
    command_prefix: '!wa'
    # Should the bridge create a space for each login containing the rooms that account is in?
    personal_filtering_spaces: false
    # Whether the bridge should set names and avatars explicitly for DM portals.
    # This is only necessary when using clients that don't support MSC4171.
    private_chat_portal_meta: true
    # Should events be handled asynchronously within portal rooms?
    # If true, events may end up being out of order, but slow events won't block other ones.
    # This is not yet safe to use.
    async_events: false
    # Should every user have their own portals rather than sharing them?
    # By default, users who are in the same group on the remote network will be
    # in the same Matrix room bridged to that group. If this is set to true,
    # every user will get their own Matrix room instead.
    split_portals: false
    # Should the bridge resend `m.bridge` events to all portals on startup?
    resend_bridge_info: false

    # Should leaving Matrix rooms be bridged as leaving groups on the remote network?
    bridge_matrix_leave: false
    # Should room tags only be synced when creating the portal? Tags mean things like favorite/pin and archive/low priority.
    # Tags currently can't be synced back to the remote network, so a continuous sync means tagging from Matrix will be undone.
    tag_only_on_create: true
    # Should room mute status only be synced when creating the portal?
    # Like tags, mutes can't currently be synced back to the remote network.
    mute_only_on_create: true

    # What should be done to portal rooms when a user logs out or is logged out?
    # Permitted values:
    #   nothing - Do nothing, let the user stay in the portals
    #   kick - Remove the user from the portal rooms, but don't delete them
    #   unbridge - Remove all ghosts in the room and disassociate it from the remote chat
    #   delete - Remove all ghosts and users from the room (i.e. delete it)
    cleanup_on_logout:
        # Should cleanup on logout be enabled at all?
        enabled: false
        # Settings for manual logouts (explicitly initiated by the Matrix user)
        manual:
            # Action for private portals which will never be shared with other Matrix users.
            private: nothing
            # Action for portals with a relay user configured.
            relayed: nothing
            # Action for portals which may be shared, but don't currently have any other Matrix users.
            shared_no_users: nothing
            # Action for portals which have other logged-in Matrix users.
            shared_has_users: nothing
        # Settings for credentials being invalidated (initiated by the remote network, possibly through user action).
        # Keys have the same meanings as in the manual section.
        bad_credentials:
            private: nothing
            relayed: nothing
            shared_no_users: nothing
            shared_has_users: nothing

    # Settings for relay mode
    relay:
        # Whether relay mode should be allowed. If allowed, the set-relay command can be used to turn any
        # authenticated user into a relaybot for that chat.
        enabled: false
        # Should only admins be allowed to set themselves as relay users?
        # If true, non-admins can only set users listed in default_relays as relays in a room.
        admin_only: true
        # List of user login IDs which anyone can set as a relay, as long as the relay user is in the room.
        default_relays: []
        # The formats to use when sending messages via the relaybot.
        # Available variables:
        #   .Sender.UserID - The Matrix user ID of the sender.
        #   .Sender.Displayname - The display name of the sender (if set).
        #   .Sender.RequiresDisambiguation - Whether the sender's name may be confused with the name of another user in the room.
        #   .Sender.DisambiguatedName - The disambiguated name of the sender. This will be the displayname if set,
        #                               plus the user ID in parentheses if the displayname is not unique.
        #                               If the displayname is not set, this is just the user ID.
        #   .Message - The `formatted_body` field of the message.
        #   .Caption - The `formatted_body` field of the message, if it's a caption. Otherwise an empty string.
        #   .FileName - The name of the file being sent.
        message_formats:
            m.text: "<b>{{ .Sender.DisambiguatedName }}</b>: {{ .Message }}"
            m.notice: "<b>{{ .Sender.DisambiguatedName }}</b>: {{ .Message }}"
            m.emote: "* <b>{{ .Sender.DisambiguatedName }}</b> {{ .Message }}"
            m.file: "<b>{{ .Sender.DisambiguatedName }}</b> sent a file{{ if .Caption }}: {{ .Caption }}{{ end }}"
            m.image: "<b>{{ .Sender.DisambiguatedName }}</b> sent an image{{ if .Caption }}: {{ .Caption }}{{ end }}"
            m.audio: "<b>{{ .Sender.DisambiguatedName }}</b> sent an audio file{{ if .Caption }}: {{ .Caption }}{{ end }}"
            m.video: "<b>{{ .Sender.DisambiguatedName }}</b> sent a video{{ if .Caption }}: {{ .Caption }}{{ end }}"
            m.location: "<b>{{ .Sender.DisambiguatedName }}</b> sent a location{{ if .Caption }}: {{ .Caption }}{{ end }}"
        # For networks that support per-message displaynames (i.e. Slack and Discord), the template for those names.
        # This has all the Sender variables available under message_formats (but without the .Sender prefix).
        # Note that you need to manually remove the displayname from message_formats above.
        displayname_format: "{{ .DisambiguatedName }}"

    # Permissions for using the bridge.
    # Permitted values:
    #    relay - Talk through the relaybot (if enabled), no access otherwise
    # commands - Access to use commands in the bridge, but not login.
    #     user - Access to use the bridge with puppeting.
    #    admin - Full access, user level with some additional administration tools.
    # Permitted keys:
    #        * - All Matrix users
    #   domain - All users on that homeserver
    #     mxid - Specific user
    permissions:
        '*': relay
        '@admin:homeserver.com': admin
        homeserver.com: user

# Config for the bridge's database.
database:
    # The database type. "sqlite3-fk-wal" and "postgres" are supported.
    type: sqlite3-fk-wal
    # The database URI.
    #   SQLite: A raw file path is supported, but `file:<path>?_txlock=immediate` is recommended.
    #           https://github.com/mattn/go-sqlite3#connection-string
    #   Postgres: Connection string. For example, postgres://user:password@host/database?sslmode=disable
    #             To connect via Unix socket, use something like postgres:///dbname?host=/var/run/postgresql
    uri: file:/data/mautrix-whatsapp.db?_txlock=immediate
    # Maximum number of connections.
    max_open_conns: 20
    max_idle_conns: 2
    # Maximum connection idle time and lifetime before they're closed. Disabled if null.
    # Parsed with https://pkg.go.dev/time#ParseDuration
    max_conn_idle_time: null
    max_conn_lifetime: null

# Homeserver details.
homeserver:
    # The address that this appservice can use to connect to the homeserver.
    # Local addresses without HTTPS are generally recommended when the bridge is running on the same machine,
    # but https also works if they run on different machines.
    address: http://serverlocalip:8008
    # The domain of the homeserver (also known as server_name, used for MXIDs, etc).
    domain: homeserver.com

    # What software is the homeserver running?
    # Standard Matrix homeservers like Synapse, Dendrite and Conduit should just use "standard" here.
    software: standard
    # The URL to push real-time bridge status to.
    # If set, the bridge will make POST requests to this URL whenever a user's remote network connection state changes.
    # The bridge will use the appservice as_token to authorize requests.
    status_endpoint: ""
    # Endpoint for reporting per-message status.
    # If set, the bridge will make POST requests to this URL when processing a message from Matrix.
    # It will make one request when receiving the message (step BRIDGE), one after decrypting if applicable
    # (step DECRYPTED) and one after sending to the remote network (step REMOTE). Errors will also be reported.
    # The bridge will use the appservice as_token to authorize requests.
    message_send_checkpoint_endpoint: null
    # Does the homeserver support https://github.com/matrix-org/matrix-spec-proposals/pull/2246?
    async_media: false

    # Should the bridge use a websocket for connecting to the homeserver?
    # The server side is currently not documented anywhere and is only implemented by mautrix-wsproxy,
    # mautrix-asmux (deprecated), and hungryserv (proprietary).
    websocket: false
    # How often should the websocket be pinged? Pinging will be disabled if this is zero.
    ping_interval_seconds: 0

# Application service host/registration related details.
# Changing these values requires regeneration of the registration (except when noted otherwise)
appservice:
    # The address that the homeserver can use to connect to this appservice.
    # Like the homeserver address, a local non-https address is recommended when the bridge is on the same machine.
    # If the bridge is elsewhere, you must secure the connection yourself (e.g. with https or wireguard)
    # If you want to use https, you need to use a reverse proxy. The bridge does not have TLS support built in.
    address: http://serverlocalip:29318
    # A public address that external services can use to reach this appservice.
    # This is only needed for things like public media. A reverse proxy is generally necessary when using this field.
    # This value doesn't affect the registration file.
    public_address: https://bridge.example.com

    # The hostname and port where this appservice should listen.
    # For Docker, you generally have to change the hostname to 0.0.0.0.
    hostname: 0.0.0.0
    port: 29318

    # The unique ID of this appservice.
    id: whatsapp
    # Appservice bot details.
    bot:
        # Username of the appservice bot.
        username: bot_whatsapp
        # Display name and avatar for bot. Set to "remove" to remove display name/avatar, leave empty
        # to leave display name/avatar as-is.
        displayname: WhatsApp Bridge Bot
        avatar: mxc://maunium.net/NeXNQarUbrlYBiPCpprYsRqr

    # Whether to receive ephemeral events via appservice transactions.
    ephemeral_events: true
    # Should incoming events be handled asynchronously?
    # This may be necessary for large public instances with lots of messages going through.
    # However, messages will not be guaranteed to be bridged in the same order they were sent in.
    # This value doesn't affect the registration file.
    async_transactions: false

    # Authentication tokens for AS <-> HS communication. Autogenerated; do not modify.
    as_token: token
    hs_token: token

    # Localpart template of MXIDs for remote users.
    # {{.}} is replaced with the internal ID of the user.
    username_template: whatsapp_{{.}}

# Config options that affect the Matrix connector of the bridge.
matrix:
    # Whether the bridge should send the message status as a custom com.beeper.message_send_status event.
    message_status_events: false
    # Whether the bridge should send a read receipt after successfully bridging a message.
    delivery_receipts: false
    # Whether the bridge should send error notices via m.notice events when a message fails to bridge.
    message_error_notices: true
    # Whether the bridge should update the m.direct account data event when double puppeting is enabled.
    sync_direct_chat_list: false
    # Whether created rooms should have federation enabled. If false, created portal rooms
    # will never be federated. Changing this option requires recreating rooms.
    federate_rooms: true
    # The threshold as bytes after which the bridge should roundtrip uploads via the disk
    # rather than keeping the whole file in memory.
    upload_file_threshold: 5242880

# Segment-compatible analytics endpoint for tracking some events, like provisioning API login and encryption errors.
analytics:
    # API key to send with tracking requests. Tracking is disabled if this is null.
    token: null
    # Address to send tracking requests to.
    url: https://api.segment.io/v1/track
    # Optional user ID for tracking events. If null, defaults to using Matrix user ID.
    user_id: null

# Settings for provisioning API
provisioning:
    # Prefix for the provisioning API paths.
    prefix: /_matrix/provision
    # Shared secret for authentication. If set to "generate" or null, a random secret will be generated,
    # or if set to "disable", the provisioning API will be disabled.
    shared_secret: secret
    # Whether to allow provisioning API requests to be authed using Matrix access tokens.
    # This follows the same rules as double puppeting to determine which server to contact to check the token,
    # which means that by default, it only works for users on the same server as the bridge.
    allow_matrix_auth: true
    # Enable debug API at /debug with provisioning authentication.
    debug_endpoints: false

# Some networks require publicly accessible media download links (e.g. for user avatars when using Discord webhooks).
# These settings control whether the bridge will provide such public media access.
public_media:
    # Should public media be enabled at all?
    # The public_address field under the appservice section MUST be set when enabling public media.
    enabled: false
    # A key for signing public media URLs.
    # If set to "generate", a random key will be generated.
    signing_key: key
    # Number of seconds that public media URLs are valid for.
    # If set to 0, URLs will never expire.
    expiry: 0
    # Length of hash to use for public media URLs. Must be between 0 and 32.
    hash_length: 32

# Settings for converting remote media to custom mxc:// URIs instead of reuploading.
# More details can be found at https://docs.mau.fi/bridges/go/discord/direct-media.html
direct_media:
    # Should custom mxc:// URIs be used instead of reuploading media?
    enabled: false
    # The server name to use for the custom mxc:// URIs.
    # This server name will effectively be a real Matrix server, it just won't implement anything other than media.
    # You must either set up .well-known delegation from this domain to the bridge, or proxy the domain directly to the bridge.
    server_name: discord-media.example.com
    # Optionally a custom .well-known response. This defaults to `server_name:443`
    well_known_response:
    # Optionally specify a custom prefix for the media ID part of the MXC URI.
    media_id_prefix:
    # If the remote network supports media downloads over HTTP, then the bridge will use MSC3860/MSC3916
    # media download redirects if the requester supports it. Optionally, you can force redirects
    # and not allow proxying at all by setting this to false.
    # This option does nothing if the remote network does not support media downloads over HTTP.
    allow_proxy: true
    # Matrix server signing key to make the federation tester pass, same format as synapse's .signing.key file.
    # This key is also used to sign the mxc:// URIs to ensure only the bridge can generate them.
    server_key: key

# Settings for backfilling messages.
# Note that the exact way settings are applied depends on the network connector.
# See https://docs.mau.fi/bridges/general/backfill.html for more details.
backfill:
    # Whether to do backfilling at all.
    enabled: true
    # Maximum number of messages to backfill in empty rooms.
    max_initial_messages: 100
    # Maximum number of missed messages to backfill after bridge restarts.
    max_catchup_messages: 500
    # If a backfilled chat is older than this number of hours,
    # mark it as read even if it's unread on the remote network.
    unread_hours_threshold: 720
    # Settings for backfilling threads within other backfills.
    threads:
        # Maximum number of messages to backfill in a new thread.
        max_initial_messages: 50
    # Settings for the backwards backfill queue. This only applies when connecting to
    # Beeper as standard Matrix servers don't support inserting messages into history.
    queue:
        # Should the backfill queue be enabled?
        enabled: false
        # Number of messages to backfill in one batch.
        batch_size: 100
        # Delay between batches in seconds.
        batch_delay: 20
        # Maximum number of batches to backfill per portal.
        # If set to -1, all available messages will be backfilled.
        max_batches: -1
        # Optional network-specific overrides for max batches.
        # Interpretation of this field depends on the network connector.
        max_batches_override: {}

# Settings for enabling double puppeting
double_puppet:
    # Servers to always allow double puppeting from.
    # This is only for other servers and should NOT contain the server the bridge is on.
    servers:
        example.com: https://example.com
    # Whether to allow client API URL discovery for other servers. When using this option,
    # users on other servers can use double puppeting even if their server URLs aren't
    # explicitly added to the servers map above.
    allow_discovery: false
    # Shared secrets for automatic double puppeting.
    # See https://docs.mau.fi/bridges/general/double-puppeting.html for instructions.
    secrets:
        example.com: foobar

# End-to-bridge encryption support options.
#
# See https://docs.mau.fi/bridges/general/end-to-bridge-encryption.html for more info.
encryption:
    # Whether to enable encryption at all. If false, the bridge will not function in encrypted rooms.
    allow: false
    # Whether to force-enable encryption in all bridged rooms.
    default: false
    # Whether to require all messages to be encrypted and drop any unencrypted messages.
    require: false
    # Whether to use MSC2409/MSC3202 instead of /sync long polling for receiving encryption-related data.
    # This option is not yet compatible with standard Matrix servers like Synapse and should not be used.
    appservice: false
    # Enable key sharing? If enabled, key requests for rooms where users are in will be fulfilled.
    # You must use a client that supports requesting keys from other users to use this feature.
    allow_key_sharing: false
    # Pickle key for encrypting encryption keys in the bridge database.
    # If set to generate, a random key will be generated.
    pickle_key: maunium.net/go/mautrix-whatsapp
    # Options for deleting megolm sessions from the bridge.
    delete_keys:
        # Beeper-specific: delete outbound sessions when hungryserv confirms
        # that the user has uploaded the key to key backup.
        delete_outbound_on_ack: false
        # Don't store outbound sessions in the inbound table.
        dont_store_outbound: false
        # Ratchet megolm sessions forward after decrypting messages.
        ratchet_on_decrypt: false
        # Delete fully used keys (index >= max_messages) after decrypting messages.
        delete_fully_used_on_decrypt: false
        # Delete previous megolm sessions from same device when receiving a new one.
        delete_prev_on_new_session: false
        # Delete megolm sessions received from a device when the device is deleted.
        delete_on_device_delete: false
        # Periodically delete megolm sessions when 2x max_age has passed since receiving the session.
        periodically_delete_expired: false
        # Delete inbound megolm sessions that don't have the received_at field used for
        # automatic ratcheting and expired session deletion. This is meant as a migration
        # to delete old keys prior to the bridge update.
        delete_outdated_inbound: false
    # What level of device verification should be required from users?
    #
    # Valid levels:
    #   unverified - Send keys to all device in the room.
    #   cross-signed-untrusted - Require valid cross-signing, but trust all cross-signing keys.
    #   cross-signed-tofu - Require valid cross-signing, trust cross-signing keys on first use (and reject changes).
    #   cross-signed-verified - Require valid cross-signing, plus a valid user signature from the bridge bot.
    #                           Note that creating user signatures from the bridge bot is not currently possible.
    #   verified - Require manual per-device verification
    #              (currently only possible by modifying the `trust` column in the `crypto_device` database table).
    verification_levels:
        # Minimum level for which the bridge should send keys to when bridging messages from the remote network to Matrix.
        receive: unverified
        # Minimum level that the bridge should accept for incoming Matrix messages.
        send: unverified
        # Minimum level that the bridge should require for accepting key requests.
        share: cross-signed-tofu
    # Options for Megolm room key rotation. These options allow you to configure the m.room.encryption event content.
    # See https://spec.matrix.org/v1.10/client-server-api/#mroomencryption for more information about that event.
    rotation:
        # Enable custom Megolm room key rotation settings. Note that these
        # settings will only apply to rooms created after this option is set.
        enable_custom: false
        # The maximum number of milliseconds a session should be used
        # before changing it. The Matrix spec recommends 604800000 (a week)
        # as the default.
        milliseconds: 604800000
        # The maximum number of messages that should be sent with a given a
        # session before changing it. The Matrix spec recommends 100 as the
        # default.
        messages: 100
        # Disable rotating keys when a user's devices change?
        # You should not enable this option unless you understand all the implications.
        disable_device_change_key_rotation: false

# Logging config. See https://github.com/tulir/zeroconfig for details.
logging:
    writers:
        - type: stdout
          format: pretty-colored
          min_level: debug
          time_format: Jan _2, 2006 15:04:05
    min_level: debug

[tulir]

The clients will have to add caption support. Element already has it on android x as well as the next release of web/desktop