## Patch project canvas

**patch** `/projects/{projectId}/canvas`

Applies a Mermaid flowchart patch to the project canvas using the same create_workflow path as the Fauna agent. The diagram may add nodes, connect nodes, and reference existing canvas nodes by their Mermaid short IDs in edges (e.g. `n1 --> out`). This endpoint is add-only: re-declaring an existing node id with a label (e.g. `n3["..."]`) creates a NEW node instead of updating the existing one, and returns a warning. To attach to an existing node, reference its id in an edge without re-declaring its label. Subgraph grouping is not applied (nodes inside a `subgraph` are added ungrouped) and returns a warning. To place an existing image/video/audio as a static node, set `node_params` — which is keyed by Mermaid node id, e.g. `{ "img1": { "content_url": "https://…" } }`, NOT a bare `{ content_url }` object. `prompt` and `content_url` are mutually exclusive for a node: use `prompt` (or a label that doubles as the prompt) for generation, or `content_url` for existing media. When using `content_url`, give the node a content-free type-only label such as `img1["(Image)"]` so no prompt is inferred from the label.

### Path Parameters

- `projectId: string`

  Project identifier

### Body Parameters

- `diagram: string`

  Mermaid flowchart diagram to apply

- `node_params: optional map[object { aspect_ratio, content_url, model, 3 more } ]`

  Optional per-node parameters, keyed by Mermaid node id (a Record<nodeId, NodeParams>), e.g. { "img1": { "content_url": "https://…" } }. Pass a map keyed by node id, NOT a bare { content_url } object.

  - `aspect_ratio: optional string`

  - `content_url: optional string`

    HTTPS URL of existing media to place as a static node. Mutually exclusive with prompt: give the node a content-free type-only label such as `(Image)` so no prompt is inferred from the label. Only supported for Image, Video, and Audio nodes.

  - `model: optional string`

  - `model_parameters: optional map[unknown]`

  - `prompt: optional string`

    Generation prompt for this node. Mutually exclusive with content_url. If omitted, the node's Mermaid label is used as the prompt.

  - `resolution: optional string`

### Returns

- `canvas_url: string`

  Project canvas URL

- `created_edge_count: number`

- `created_node_count: number`

- `diagram: string`

  Applied Mermaid flowchart diagram

- `project_id: string`

  Project identifier

- `warnings: optional array of string`

### Example

```http
curl https://app.flora.ai/api/v1/projects/$PROJECT_ID/canvas \
    -X PATCH \
    -H 'Content-Type: application/json' \
    -H "Authorization: Bearer $FLORA_API_KEY" \
    -d '{
          "diagram": "graph LR\\n  source[\\"Product photo (Image)\\"]\\n  output[\\"Editorial campaign image (Image)\\"]\\n  source --> output"
        }'
```

#### Response

```json
{
  "canvas_url": "https://example.com",
  "created_edge_count": 0,
  "created_node_count": 0,
  "diagram": "graph LR\n  n1[\"Prompt (text)\"]\n  n2[\"Result (image)\"]\n  n1 --> n2",
  "project_id": "prj_abc123",
  "warnings": [
    "string"
  ]
}
```