---
title: "Save Work Channel Canvas"
method: POST
path: "/work/channels/{channel_id}/canvas"
tags: ["Work"]
---

# Save Work Channel Canvas

`POST /work/channels/{channel_id}/canvas`

## Request

- Base URL: `https://be.graph8.com/api/v1`
- URL: `https://be.graph8.com/api/v1/work/channels/{channel_id}/canvas`
- Auth: HTTP bearer

Replace one channel's Canvas from its content. Signed server-side.

The counterpart of the published ``GET`` on this path. It is the app's
``POST`` (bare content, revision authored server-side with the caller's
derived key), not the ``PUT`` that accepts a client-SIGNED event, which a
machine principal has no signing story for.

``baseRevisionId`` is a compare-and-swap: send the ``revisionId`` the
``GET`` gave you, omit it to skip the check, or send ``""`` to assert no
canvas existed. ``403`` when the caller may not edit the channel; ``409``
for an archived channel, a replayed key with a different body, or a stale
``baseRevisionId``.

## Path parameters

- `channel_id` string, required: Channel id or slug

## Headers

- `Idempotency-Key` string, nullable: Retry-safety key. Replaying one returns the ORIGINAL result with `duplicate: true` instead of writing twice. Omit it and the server mints a single-use key, which means a retried request writes again — send your own for anything you may retry.
- `Authorization` string, nullable
- `X-Target-Org-Id` string, nullable

## Request body

- WorkCanvasSaveRequest: One channel canvas replacement, by CONTENT. The channel is named by the path, the author by the session, the idempotency key by the header — this body carries only the markdown. An empty string is a legal canvas (it clears the document); the 100k ceiling is the gateway's own. Server-owned fields are refused by name rather than swallowed by `extra="forbid"`, matching every other Work write DTO: a client that believes it is choosing the author must be told it is not.
  - `content` string, required
  - `baseRevisionId` string, nullable

## Response `200`

Successful Response

- ApiResponseWorkCanvas
  - `data` WorkCanvas, required: One channel's Canvas document.
    - `channelId` string, nullable: Channel the canvas belongs to
    - `content` string, nullable: Canvas content
    - `revisionId` string, nullable: Current revision id
  - `pagination` PaginationMeta
    - `page` integer, required: Current page number (1-indexed)
    - `limit` integer, required: Items per page
    - `total` integer, required: Total number of items
    - `has_next` boolean, required: Whether there are more pages
    - `next_cursor` string, nullable: Opaque cursor for the next page; null when there are no more items. Pass it back as the `cursor` query param to fetch the following page without computing page numbers.
    - `total_available` integer, nullable: Search endpoints only: how many records really match, when known. Can be larger than `total`, which is capped at the 10,000 results that can be paged. For company search this is a distinct-company estimate. Null when unknown; absent outside search.
    - `total_is_lower_bound` boolean, nullable: Search endpoints only: true when more records match than `total` shows (the result set is larger than the 10,000 results that can be paged). Absent outside search.
    - `notes` string[], nullable: Search endpoints only: plain-language notes about the result, e.g. that more records match than can be paged, or that a reversed `between` range was put in order.

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/graph8/apis/graph8-developer-api.md) · [All operations](https://skmtc.dev/graph8/apis/graph8-developer-api/llms.txt) · [OpenAPI document](https://skmtc.dev/graph8/apis/graph8-developer-api/revisions/2e7cfa0ca921?raw)