The canvas¶

The canvas holds the objects you and your agent work on: document cards, specification tables, notes, shapes, and engineering objects. It belongs to a project and uses that project's document corpus.

Open and navigate¶

Start anchor serve for the desired environment and project, open the printed URL, and choose a canvas. A canvas URL ends with /c/<slug>. One server serves one project; the same canvas slug can exist in another project.

Use the left rail to place cards and shapes, add producer files, or enter the mark-up tool. The files explorer and source dock sit beside the canvas and can be toggled with [ when you are not typing. Select a node for its context toolbar and properties, drag to move it, and use handles where supported for resizing or connections. Shift-click or a selection box selects several objects.

Drag empty canvas to pan the view. Shift-drag to draw a selection box. Click or drag an object to select or move it.

Hold Space and drag anywhere to pan: over a card, it pans instead of moving the card, and in mark-up it lifts the pen for as long as Space is held. Press V to put down an armed tool. While a tool is armed, middle-button and right-button dragging pan the view. These keys leave text editors and source controls alone.

Double-click empty canvas to place a text element and start typing. Press Enter or click away to save, or Escape to cancel the current text edit. Double-click an existing shape to edit its label.

Common objects¶

Node type	Purpose
`document`	Card for a PDF in the project corpus
`spec`	Related parameters or specifications, with one source reference per row
`markdown`	Structured prose, lists, tables, and code
`fact`, `concept`, `entity`	General knowledge cards or shapes
`area`	Container for related canvas objects
`canvas`	Tile linking to another canvas
`cad:model`	CAD model view and supported parameter operations
`fmu`	FMU model with variables and simulation controls when its runtime is available

Other shapes and producer objects are registered by the browser and bundled extensions. Renderers live under web/src/canvas/primitives/ and web/src/canvas/shapes/; web/src/canvas/registry.ts maps node types to them. Use anchor canvas node-types or MCP canvas_node_types for the live data-field contract rather than inventing a field the renderer does not use.

Tables and source evidence¶

Keep related extracted values in one spec table. Each row has a key, value, and optional source_ref. A PDF source can name the document slug, one-based page, region/item/cell selectors, or an explicit bounding box. Boxes use PDF points, a top-left origin, and [left, top, right, bottom].

Click a row's source anchor to open the PDF dock. It highlights a precise locator when one resolves, or opens the cited page otherwise. Selecting source text can attach a more precise box. A source link makes the claim inspectable; it does not confer Verified status by itself.

Rows distinguish Verified, Unverified, Stale, and No evidence. Editing a claim can preserve the link while making its binding stale. Use Check to request revalidation against stored evidence. See Claim and evidence and Source resolution.

Headings, folding, and details¶

Choose Heading from the shape palette to place a section label. It creates a concept with data.role: "heading": a large label and optional subtitle, without the card border or body. Select an existing concept and choose Appearance > Heading in its properties to give it the same presentation.

A node with children has a collapse button above it. Folding hides descendants and every edge touching a hidden node. The folded root stays visible, including its own evidence link, and its +4 badge counts the descendants currently hidden. Expand to restore their saved positions. A shared child stays visible if another visible, expanded parent reaches it. Cycles are visited once, and a cyclic component keeps an expand affordance.

Folding follows structural edges and area containment. Child direction in properties uses the organizer's outgoing, incoming, or any direction convention; the default is outgoing. Edge labels such as contains and part_of do not change that direction. Evidence edges never make the source document a child of a fact. A document card additionally treats incoming evidence dependents as children, so it can fold its sourced claims.

Fact, note, Markdown, and spec cards default to Compact: the label and first line or row count. Double-click a compact card, or select any node and choose Details, to read the complete content, rows, source references and crops, evidence links, stored review record, and requests that target it. Source actions open the document viewer at the resolved page. Region/item references without a page are resolved before opening; an unavailable source keeps its reference visible. Document cards retain double-click to open the PDF, and sub-canvas tiles retain double-click to navigate. Their Details action is separate.

Choose Display > Full to keep one important card or table expanded on the canvas. Full tables retain their inline row editing and source anchors. The detail view also offers Edit properties for the existing editing panel. Read-only canvases allow detail reading and source opening without editing.

These settings are ordinary persisted node data. HTTP node patches, MCP canvas_add_node / canvas_update_node, and CLI anchor canvas add-node / anchor canvas update-node all use the same fields:

{
  "collapsed": true,
  "collapse_direction": "outgoing",
  "role": "heading"
}

Use data.display_mode: "compact" or "full" on a card. Every viewer reads the same persisted fold. canvas_get_state and CLI canvas state still return all nodes, edges, source data, and positions; folding only filters rendering.

Requests and review¶

Use mark up (i) to add text and drawings about visible objects. Click send to agent to create a persistent project-level intent. A connected external agent must retrieve and handle it; an empty placeholder does not submit an ask. The remark stays on the board with its request thread.

The agent can ask a question or stage a suggested edit. Inspect the preview and approve, decline, or send feedback. Applied small changes may offer keep/revert controls. These are scoped to the thread change, not a general undo history. Canvas review mode and proposal sets support review of agent-added elements separately. See the tutorial.

PDF upload¶

Drop a PDF on the canvas or use + > PDF datasheet. A card shows its processing status. With local or an endpoint-backed provider, the server runs the built-in pipeline. With harness, it saves the PDF and queues a drop_to_ingest intent; the card stays awaiting agent until the harness completes the session.

CLI ingestion writes the corpus without adding a canvas card. Drag a document from the files explorer onto the canvas to place it. See Documents and canvases.

Edges and organization¶

Connect plain shapes with a floating edge, the default, using only the source and target node IDs. Leave sourceHandle and targetHandle unset in HTTP/MCP, or omit --source-handle and --target-handle in the CLI. Floating routing chooses the facing sides of each node; plain shapes have no named left or right ports to guess. The connector tool and selected-node quick-connect dots create these node-to-node connections.

Use anchored edges when a position carries meaning, such as a specification row, document region, or model port. Supply the exact handle IDs exposed by that feature. When updating an edge, omitting a handle field keeps its current value unchanged.

Area nodes can contain child nodes; sub-canvas tiles link to another workspace. Layout operations include alignment, distribution, and subtree organization. CLI/MCP add operations can auto-place nodes when coordinates are omitted; explicit coordinates preserve a chosen layout.

Edges draw above areas and nodes in the background layer, and below ordinary cards and annotations. Selecting an edge or nesting an endpoint keeps that order. A crossing disappears behind an opaque card; transparent objects can still show the line beneath them. This does not change edge routes or bundle shared endpoints.

FMU nodes remain separate from extracted knowledge. Inspect a model and wire table rows to appropriate parameters deliberately. Simulation needs the optional runtime; explicitly enabled demo output is synthetic.

Persistence and live updates¶

Each canvas has metadata, state, and an append-only event log under .anchor_data/canvases/<slug>/. Documents remain in the project's separate corpus folders. Deleting a canvas does not delete those documents. Copy the whole project for a backup that includes its source evidence and intent threads.

The browser sends writes through HTTP and receives snapshots and patches over SSE. The HTTP process also tails canvas events persisted by CLI and MCP writers. Local optimistic edits are reconciled against server state. If views disagree, check project selection and re-read or reload the persisted state.

There is no fixed latency guarantee. Write locks and event buses are process-local; avoid simultaneous mutations to the same canvas from separate processes.