React to Event
matrix.send_reaction
ActionChat & messagingconnection required
Calls the Matrix API with the connection's credentials.
Add an emoji reaction to an event as an m.reaction annotation.
Connection
- Required
- Yes — the node will not save without one
- Auth type
- Bearer token
- Providers
- Matrix
- Secret shape
- the account access token, or {"access_token": "…"}
- Config it needs
- base_url, user_id, default_room_id
- Resolved by
- config.connection_id, else node.connection_id
Configuration
4 fields, 2 required. A dotted path is a nested object and name[] an array of objects — the editor renders the same tree.
| Field | Type | Required | Default | Constraints | Example |
|---|---|---|---|---|---|
room_id The room id, e.g. !AbCdEf:example.org. Falls back to the connection's default room; resolve a #alias:server with matrix.resolve_room_alias. | string | No | — | — | !AbCdEf:example.org |
event_id The event being reacted to, e.g. $abc123:example.org. | string | Yes | — | — | — |
key The reaction itself — an emoji such as 👍, or short text. | string | Yes | — | — | 👍 |
txn_id Transaction id that makes this send idempotent — the same id never posts twice. Leave blank for a fresh id on every attempt. | string | No | — | — | — |
Example configuration
Every value below is the contract’s own example or default — nothing invented.
{
"key": "👍",
"room_id": "!AbCdEf:example.org"
}Output
One shape.
result
| Field | Type | Example |
|---|---|---|
event_id The id of the event that was sent. | string | $abc123:example.org |
room_id The room the event was sent to. | string | — |
txn_id The transaction id used; resend with it to avoid a duplicate. | string | — |
{
"event_id": "$abc123:example.org",
"room_id": "",
"txn_id": ""
}Notes
- The connection's base_url is the homeserver (e.g. https://matrix.example.org), not the account's server name; the two differ whenever .well-known delegation is in use.
- Rooms are addressed by room id (!abc:server). Resolve a #alias:server with matrix.resolve_room_alias first, or set a default room on the connection.
See React to Event run in a workflow.
In a technical demo we add the Matrix connection, drop the node on the canvas and let Workflow Health pre-flight it before the first real run.