HackMD
    • Create new note
    • Create a note from template
    • Sharing Link copied
    • /edit
    • View mode
      • Edit mode
      • View mode
      • Book mode
      • Slide mode
      Edit mode View mode Book mode Slide mode
    • Customize slides
    • Note Permission
    • Read
      • Only me
      • Signed-in users
      • Everyone
      Only me Signed-in users Everyone
    • Write
      • Only me
      • Signed-in users
      • Everyone
      Only me Signed-in users Everyone
    • Commenting & Invitee
    • Publishing
      Please check the box to agree to the Community Guidelines.
      Everyone on the web can find and read all notes of this public team.
      After the note is published, everyone on the web can find and read this note.
      See all published notes on profile page.
    • Commenting Enable
      Disabled Forbidden Owners Signed-in users Everyone
    • Permission
      • Forbidden
      • Owners
      • Signed-in users
      • Everyone
    • Invitee
    • No invitee
    • Options
    • Versions and GitHub Sync
    • Transfer ownership
    • Delete this note
    • Note settings
    • Template
    • Save as template
    • Insert from template
    • Export
    • Dropbox
    • Google Drive Export to Google Drive
    • Gist
    • Import
    • Dropbox
    • Google Drive Import from Google Drive
    • Gist
    • Clipboard
    • Download
    • Markdown
    • HTML
    • Raw HTML
Menu Note settings Sharing Create Help
Create Create new note Create a note from template
Menu
Options
Versions and GitHub Sync Transfer ownership Delete this note
Export
Dropbox Google Drive Export to Google Drive Gist
Import
Dropbox Google Drive Import from Google Drive Gist Clipboard
Download
Markdown HTML Raw HTML
Back
Sharing
Sharing Link copied
/edit
View mode
  • Edit mode
  • View mode
  • Book mode
  • Slide mode
Edit mode View mode Book mode Slide mode
Customize slides
Note Permission
Read
Only me
  • Only me
  • Signed-in users
  • Everyone
Only me Signed-in users Everyone
Write
Only me
  • Only me
  • Signed-in users
  • Everyone
Only me Signed-in users Everyone
Comment & Invitee
Publishing
Please check the box to agree to the Community Guidelines.
Everyone on the web can find and read all notes of this public team.
After the note is published, everyone on the web can find and read this note.
See all published notes on profile page.
More (Comment, Invitee)
Commenting Enable
Disabled Forbidden Owners Signed-in users Everyone
Permission
Owners
  • Forbidden
  • Owners
  • Signed-in users
  • Everyone
Invitee
No invitee
   owned this note    owned this note      
Published Linked with GitHub
Like BookmarkBookmarked
Subscribed
  • Any changes
    Be notified of any changes
  • Mention me
    Be notified of mention me
  • Unsubscribe
Subscribe
# Read receipts for threads ## Problem statement In order for [notifications in threads](https://github.com/vector-im/element-meta/issues/196) to be accurate clients need to able to synchronize whether threads have been read or not. This is done using read receipts in the main timeline. Tracking of whether a user has read a thread needs to be performed as the single read receipt for a room is not enough information to know whether messages in a thread have been viewed. ### Requirements * For each thread in a room: * Sync the read status of a thread across clients. * Let the user know if there are unread messages in threads the user has participated in. * Do not consider threaded messages in the notification counts. ## Background ### Receipts Matrix uses "receipts" to note which part of a room has been read by a user. It considers the history for a room to be split into three sections[^1]: 1. Messages the user has read (or indicated they aren’t interested in them). 2. Messages the user might have read some but not others. 3. Messages the user hasn’t seen yet. The **fully read marker** is between 1 & 2 while the **read receipt** is between 2 & 3. Note that fully read markers are not shared with other users while read receipts are. Another way to consider this is[^2]: 1. **Fully read marker**: a private bookmark to indicate the point which has been processed in the discussion. This allows a user to go back to it later. 2. **Read receipts**: public indicators of what a user has seen to inform other participants that the user has seen it. 3. **Hidden read receipts**: a private mechanism to synchronize "unread messages" indicators between a user's devices (while still retaining the ability from 1 as a separate concept). #### [Fully read markers](https://spec.matrix.org/latest/client-server-api/#fully-read-markers) They are stored in the room account data for the user (but modified via a separate API). API is: `POST /_matrix/client/v3/rooms/{roomId}/read_markers` The read receipt can optionally be updated at the same time. In Element Web your fully read marker is displayed as the green line across the conversation. #### [Read receipts](https://spec.matrix.org/latest/client-server-api/#receipts) Only `m.read` is defined at the moment, but it is meant to be generic infrastructure. Updating a read receipt updates a "marker" which causes any notifications prior to and including the event to be marked as read.[^3] A user has a single read receipt "marker" per room. Passed to clients as an `m.receipt` event under the `ephemeral` array for each room in the `/sync` response. The event includes a map of event ID -> receipt type -> user ID -> data (currently just a timestamp). Note that the event is a delta from previous events. An example: ```json { "content": { "$1435641916114394fHBLK:matrix.org": { "m.read": { "@rikj:jki.re": { "ts": 1436451550453 } } } }, "room_id": "!jEsUZKDJdhlrceRyVU:example.org", "type": "m.receipt" } ``` API is: `POST /_matrix/client/v3/rooms/{roomId}/receipt/{receiptType}/{eventId}` In Element Web read receipts are the small avatars on the right hand side of the conversation. Note that your own read receipt is not shown. #### [Hidden read receipts (MSC2285)](https://github.com/matrix-org/matrix-spec-proposals/pull/2285) A new receipt type (`m.read.hidden`) to set a read receipt without sharing it with other users. It also modifies the `/read_markers` API to accept the new receipt type. This is useful to synchronize notifications across devices while keeping read status private. ### [Push rules](https://spec.matrix.org/v1.2/client-server-api/#push-rules) A user's push rules determine one or more user-specific actions on each event. They are customizable, but the homeserver provides default rules. They can result in an action to: 1. Do nothing 2. Notify the user (`notify` action), which can have additional actions: 1. Highlight the message (`highlight` action) 2. Play a sound (`sound` action) By default, all new `m.room.message` and `m.room.encrypted` events generate a notification, events with a user's username in them or `@room` generate highlights, etc. #### [Push rules for relations (MSC3664)](https://github.com/matrix-org/matrix-spec-proposals/pull/3664) Augments push rules to allow applying them to the target of an event relationship and defines a default push rule for replies (not using the reply fallback). #### [Event notification attributes and actions (MSC2785)](https://github.com/matrix-org/matrix-spec-proposals/pull/2785) A proposed replacement for push rules, the results are essentially the same actions (and presumedly would not change how the data relates to `/sync`, see below). ### [Notification counts in `/sync`](https://spec.matrix.org/latest/client-server-api/#get_matrixclientv3sync) The number of notification events and highlight events since the user's last read receipt are both returned on a per room basis as part of a `/sync` response (for joined room). Notification and highlight events are any messages where the push rules resulted in an action of `notify` or `highlight`, respectively. (Note that a `highlight` action must be a `nofity` action, thus `highlight_count <= notification_count`.) An example: ```json { "account_data": [...], "ephemeral": [...], "state": [...], "summary": {...}, "timeline": {...}, "unread_notifications": { "highlight_count": 0, "notification_count": 0 } } ``` #### [Unread messages count (MSC2654)](https://github.com/matrix-org/matrix-spec-proposals/pull/2654) A new field is added under the `unread_notifications` field (`unread_count`) which is the total number of events matching particular criteria since the user's last read receipt. This replaces [MSC2625](https://github.com/matrix-org/matrix-spec-proposals/pull/2625), which adds a new push rule action (`mark_unread`) to perform the same task. In this rendition, `notify` implies `mark_unread` and thus `highlight_count <= notification_count <= unread_count`. ### [Push notifications](https://spec.matrix.org/v1.2/push-gateway-api/#post_matrixpushv1notify) Push notifications receive either the number of unread messages (across all rooms) or the number of rooms with unread messages (depending on the value of `push.group_unread_count_by_room` in the Synapse configuration). Unread messages are any messages where the push rules resulted in an action of `notify`. This information is sent from the homeserver to the push gateway as part of every notification: ```json { "notifications": { "counts": { "unread": 1, ... }, ... } } ``` ## Potential solution A new receipt type will be added (`m.thread_read`), this will behave slightly differently to `m.read` in that multiple must exist per user per room. (One per thread would exist.) This would be achieved by including a `key` field in the receipt, set to the the thread ID (the event ID of the root event, the same as what is used for the `m.thread` relation from [MSC3440](https://github.com/matrix-org/matrix-spec-proposals/pull/3440)). For this, we use the following API: ``` /_matrix/client/v3/rooms/{roomId}/receipt/m.thread_read/{eventId} { "key": "{threadId}" } ``` Each receipt then would be unique over `(roomId, userId, receiptType, key)` instead of `(roomId, userId, receiptType)`. This could then be returned from sync as a map of event ID -> receipt type -> user ID -> {key, timestamp}, as part of the standard `ephemeral` events key for joined rooms. ```json { "content": { "$1435641916114394fHBLK:matrix.org": { "m.read_thread": { "@rikj:jki.re": { "key": "$aaaaaaaaaa:matrix.org", "ts": 1436451550453 } } } }, "room_id": "!jEsUZKDJdhlrceRyVU:example.org", "type": "m.receipt" } ``` This seems to match the expectations that clients generally wish to query what the read status of an event is, although Element Web stores this information twice: 1. A mapping of receipt type -> user ID -> event ID + timestamp 2. A map of event ID -> list of (user, receipt type, timestamp) Additionally, threaded events (any event with a `rel_type` set to `m.thread`) should no longer be considered when calculating the notification count for a room as a whole. TODO Default push rule to ignore threaded messages To control notification counts for a specific thread, a client can configure a push rule per thread: `PUT /_matrix/client/v3/pushrules/global/underride/{ruleId}` ```json { "kind": "underride", // TBD If this makes sense. "conditions": [ // Maybe also match the room? { "kind": "event_match", "key": "content.relates_to.rel_type", "pattern": "m.thread" }, { "kind": "event_match", "key": "content.relates_to.event_id", "pattern": "$abcd" // The event ID of the thread root. } ], "actions": [ "notify", { "set_tweak": "thread", "value": "$abcd" // The event ID of the thread root. }, ] } ``` These would then come down `/sync`...? Somehow? How do we avoid making individual queries for every thread? Note that no changes to push notifications will be necessary at this time. ### Technical Questions * How do we make this compatible with clients that don't support viewing threads separately? * How (if at all) does this interact with the fully read marker? * Should that API be modified to also push the `m.thread_read` receipt forward or does that not make sense? ## Implementation notes ### Synapse Synapse [stores receipts twice](https://github.com/matrix-org/synapse/blob/41cf4c2cf6432336cc7477f130a2847449cff99a/synapse/storage/databases/main/receipts.py#L593-L667): 1. Linearized 2. As a graph A missing key can likely be treated as a null value of sorts in the database (as long as we can ensure uniqueness there). ### Element Web matrix-js-sdk [stores the read receipts as two maps](https://github.com/matrix-org/matrix-js-sdk/blob/2910e62bb68db2e9bdf9eeb5b5d13d5bb269c424/src/models/room.ts#L149-L154): * A map of receipt type -> user ID -> a pair of IWrappedReceipt (which encapsulates the event ID and IReceipt, which encapsulates the timestamp) * A map of event ID -> list of ICachedReceipt (which encapsulates the user, receipt type, and data) There's two ways to look up data for a room: * Where has this user read up to? * Who has read up to this message? [^1]: From [the fully read marker](https://spec.matrix.org/latest/client-server-api/#fully-read-markers) specification. [^2]: See [a discussion on MSC2285](https://github.com/matrix-org/matrix-spec-proposals/pull/2285#discussion_r436383889). [^3]: [Spec on receiving notifications](https://spec.matrix.org/latest/client-server-api/#receiving-notifications)

Import from clipboard

Advanced permission required

Your current role can only read. Ask the system administrator to acquire write and comment permission.

This team is disabled

Sorry, this team is disabled. You can't edit this note.

This note is locked

Sorry, only owner can edit this note.

Reach the limit

Sorry, you've reached the max length this note can be.
Please reduce the content or divide it to more notes, thank you!

Import from Gist

Import from Snippet

or

Export to Snippet

Are you sure?

Do you really want to delete this note?
All users will lost their connection.

Create a note from template

Create a note from template

Oops...
This template is not available.


Upgrade

All
  • All
  • Team
No template found.

Create custom template


Upgrade

Delete template

Do you really want to delete this template?

This page need refresh

You have an incompatible client version.
Refresh to update.
New version available!
See releases notes here
Refresh to enjoy new features.
Your user state has changed.
Refresh to load new user state.

Sign in

Forgot password

or

By clicking below, you agree to our terms of service.

Sign in via Facebook Sign in via Twitter Sign in via GitHub Sign in via Dropbox

New to HackMD? Sign up

Help

  • English
  • 中文
  • Français
  • Deutsch
  • 日本語
  • Español
  • Català
  • Ελληνικά
  • Português
  • italiano
  • Türkçe
  • Русский
  • Nederlands
  • hrvatski jezik
  • język polski
  • Українська
  • हिन्दी
  • svenska
  • Esperanto
  • dansk

Documents

Tutorials

Book Mode Tutorial

Slide Mode Tutorial

YAML Metadata

Contacts

Facebook

Twitter

Discord

Feedback

Send us email

Resources

Releases

Pricing

Blog

Policy

Terms

Privacy

Cheatsheet

Syntax Example Reference
# Header Header 基本排版
- Unordered List
  • Unordered List
1. Ordered List
  1. Ordered List
- [ ] Todo List
  • Todo List
> Blockquote
Blockquote
**Bold font** Bold font
*Italics font* Italics font
~~Strikethrough~~ Strikethrough
19^th^ 19th
H~2~O H2O
++Inserted text++ Inserted text
==Marked text== Marked text
[link text](https:// "title") Link
![image alt](https:// "title") Image
`Code` Code 在筆記中貼入程式碼
```javascript
var i = 0;
```
var i = 0;
:smile: :smile: Emoji list
{%youtube youtube_id %} Externals
$L^aT_eX$ LaTeX
:::info
This is a alert area.
:::

This is a alert area.

Versions

Versions and GitHub Sync

Sign in to link this note to GitHub Learn more
This note is not linked with GitHub Learn more
 
Add badge Pull Push GitHub Link Settings
Upgrade now

Version named by    

More Less
  • Edit
  • Delete

Note content is identical to the latest version.
Compare with
    Choose a version
    No search result
    Version not found

Feedback

Submission failed, please try again

Thanks for your support.

On a scale of 0-10, how likely is it that you would recommend HackMD to your friends, family or business associates?

Please give us some advice and help us improve HackMD.

 

Thanks for your feedback

Remove version name

Do you want to remove this version name and description?

Transfer ownership

Transfer to
    Warning: is a public team. If you transfer note to this team, everyone on the web can find and read this note.

      Link with GitHub

      Please authorize HackMD on GitHub

      Please sign in to GitHub and install the HackMD app on your GitHub repo. Learn more

       Sign in to GitHub

      HackMD links with GitHub through a GitHub App. You can choose which repo to install our App.

      Push the note to GitHub Push to GitHub Pull a file from GitHub

        Authorize again
       

      Choose which file to push to

      Select repo
      Refresh Authorize more repos
      Select branch
      Select file
      Select branch
      Choose version(s) to push
      • Save a new version and push
      • Choose from existing versions
      Available push count

      Upgrade

      Pull from GitHub

       
      File from GitHub
      File from HackMD

      GitHub Link Settings

      File linked

      Linked by
      File path
      Last synced branch
      Available push count

      Upgrade

      Danger Zone

      Unlink
      You will no longer receive notification when GitHub file changes after unlink.

      Syncing

      Push failed

      Push successfully