echo6-docs/vault/archive/matrix/hookshot_payload_discovery.md

Hookshot Outbound Webhook Payload Discovery

Generated: 2026-04-09 (Phase 6.0, Question 4)

NOTE: Hookshot is BLOCKED for this use case (E2EE + MAS incompatibility).

This file documents the payload shape for completeness and future reference.

Outbound Webhook Config

Enable in hookshot config.yml:

generic:
  outbound: true

HTTP Method and Content-Type

• Method: PUT (default) or POST (configurable per-connection)
• Content-Type: multipart/form-data
• Two parts:
  1. event file: Raw Matrix event JSON
  2. media file (optional): Attached media if the event references it

Headers

Header	Description
X-Matrix-Hookshot-EventId	Matrix event ID
X-Matrix-Hookshot-RoomId	Room ID
X-Matrix-Hookshot-Token	Per-webhook auth token (for receiver verification)

Event Type Coverage

ALL events in the room are forwarded. Specifically:

Event Type	Forwarded?	Notes
m.room.message	Yes	Normal messages
m.room.redaction	Yes	Deletions
m.room.message with m.relates_to/m.replace	Yes	Edits (m.new_content present)
m.room.message with m.relates_to/m.in_reply_to	Yes	Replies
m.reaction	Yes	Reactions
m.room.member	Yes	Joins/leaves/invites
State events	Yes	All state changes

The docs state: "All events that occur in the room will be sent to the outbound URL, so be careful to ensure your remote service can filter the traffic appropriately."

Encrypted Room Behavior

IF encryption is working (which it's NOT with MAS — see hookshot_e2ee_discovery.ref):

• The event payload contains DECRYPTED plaintext content
• The receiver sees the same JSON as an unencrypted room

IF encryption is NOT working:

• The event payload contains the encrypted blob (m.room.encrypted type)
• Content is unusable ciphertext

Sample Payload (from docs/source)

{
  "type": "m.room.message",
  "sender": "@signal_abc123:echo6.co",
  "event_id": "$abc123:echo6.co",
  "room_id": "!XUeWZuPdWQQnUYLJBJ:echo6.co",
  "origin_server_ts": 1775773462151,
  "content": {
    "msgtype": "m.text",
    "body": "Hello from Signal"
  },
  "unsigned": {
    "age": 42
  }
}

Edit event example:

{
  "type": "m.room.message",
  "sender": "@signal_abc123:echo6.co",
  "event_id": "$edit123:echo6.co",
  "room_id": "!XUeWZuPdWQQnUYLJBJ:echo6.co",
  "origin_server_ts": 1775773462200,
  "content": {
    "msgtype": "m.text",
    "body": "* Hello from Signal (edited)",
    "m.new_content": {
      "msgtype": "m.text",
      "body": "Hello from Signal (edited)"
    },
    "m.relates_to": {
      "rel_type": "m.replace",
      "event_id": "$abc123:echo6.co"
    }
  }
}

Filtering

No built-in filtering. The receiver must filter by type field. Hookshot sends everything — the receiver decides what to keep.

Retry Behavior

Failed deliveries are retried up to 5 times with increasing delays.

Source

• https://matrix-org.github.io/matrix-hookshot/latest/setup/webhooks.html
• https://github.com/matrix-org/matrix-hookshot/blob/main/docs/setup/webhooks.md
• https://github.com/matrix-org/matrix-hookshot/pull/945