Tldraw Skill

tldraw Whiteboard Diagrams

Overview

Generate modern whiteboard-style diagrams as .tldr JSON files and export to PNG/SVG using @kitschpatrol/tldraw-cli. tldraw produces clean hand-drawn aesthetic diagrams with rich shape libraries and smooth arrow routing — well-suited for casual or whiteboard-style visualizations.

Format: .tldr JSON Export: PNG, SVG (via @kitschpatrol/tldraw-cli) Aesthetic: Hand-drawn whiteboard style by default; switchable to clean fonts via font prop.

When to Use

Explicit triggers: user says "diagram", "flowchart", "draw", "visualize", "whiteboard diagram", "tldraw diagram", "architecture diagram", "sketch this out".

Proactive triggers:

• Explaining a system with 3+ interacting components
• Describing a multi-step process, data flow, or pipeline
• Showing relationships between services/modules
• Architecture overviews, sequence flows, decision trees, ML model layers

Skip when: a simple list or table suffices, the user wants a polished business-presentation diagram (prefer drawio-skill), or the user is in a quick Q&A flow.

Prerequisites

# Install tldraw-cli
npm install -g @kitschpatrol/tldraw-cli

# Verify
tldraw --version

Works identically on macOS, Windows, and Linux.

First-export note: tldraw export renders through a pinned Chrome build via puppeteer. The first export can fail with Could not find Chrome (ver. <x>). The error names the exact version it needs — install it once, then exports work:

# The error message names the version; substitute it here
npx puppeteer browsers install chrome@<version-from-error>

(Installs to ~/.cache/puppeteer; only needed once per CLI version.)

Workflow

Before starting, assess whether the user's request is specific enough. If key details are missing, ask 1-3 focused questions:

• Diagram type — which preset? (Architecture, Flowchart, Sequence, ML/DL, ERD, UML, or general)
• Output format — PNG (default), SVG?
• Output location — default is the user's working dir; honor any explicit path the user gives (e.g. "put it in ./artifacts/"). Don't ask if they didn't mention one.
• Scope/fidelity — how many components? Any specific technologies or labels?

Skip clarification if the request already specifies these details or is clearly simple (e.g., "draw a flowchart of X").

1. Check deps — verify tldraw --version succeeds; if missing, run npm install -g @kitschpatrol/tldraw-cli.
2. Plan — identify shapes (geo type per node), connections (arrows with source/target), and layout (TB or LR, group by tier/role). Sketch a coordinate grid before writing JSON.
3. Generate — write the .tldr JSON file. Default output dir is the user's working dir; if the user specified a path or directory (e.g. ./artifacts/), mkdir -p it first and write there. Apply the same dir choice to PNG/SVG exports in steps 4 and 7.
4. Export draft — run CLI to produce a PNG for preview.
5. Self-check — use the agent's built-in vision capability to read the exported PNG, catch obvious issues, auto-fix before showing the user (requires a vision-enabled model such as Claude Sonnet/Opus). If vision is unavailable, skip this step.
6. Review loop — show image to user, collect feedback, apply targeted JSON edits, re-export, repeat until approved.
7. Final export — export the approved version to all requested formats; report file paths for both the .tldr source and exported image(s).

Step 5: Self-Check

After exporting the draft PNG, use the agent's vision capability (e.g., Claude's image input) to read the image and check for these issues before showing the user. If the agent does not support vision, skip self-check and show the PNG directly.

tldraw's own AI agent flags exactly three structural defects — text overflow (a box too small for its label), overlapping text, and friendless arrows (an arrow with an unbound end). The first three rows below target those; size boxes correctly up front (see "Sizing boxes to fit labels") and they rarely occur.

• Max 2 self-check rounds — if issues remain after 2 fixes, show the user anyway.
• Re-export after each fix and re-read the new PNG.

Step 6: Review Loop

After self-check, show the exported image and ask the user for feedback.

Targeted edit rules — for each type of feedback, apply the minimal JSON change:

Rules:

• For single-element changes: edit the existing JSON in place — preserves layout tuning from prior iterations.
• For layout-wide changes (e.g., swap LR↔TB, "start over"): regenerate full JSON.
• Overwrite the same {name}.png each iteration — do not create v1, v2, v3 files.
• After applying edits, re-export and show the updated image.
• Loop continues until user says approved / done / LGTM.
• Safety valve: after 5 iteration rounds, suggest the user open the .tldr file in tldraw.com or the desktop app for fine-grained adjustments.

File Format

Complete .tldr Skeleton

{
  "tldrawFileFormatVersion": 1,
  "schema": {
    "schemaVersion": 1,
    "storeVersion": 4,
    "recordVersions": {
      "asset": {"version": 1, "subTypeKey": "type", "subTypeVersions": {"image": 2, "video": 2, "bookmark": 0}},
      "camera": {"version": 1},
      "document": {"version": 2},
      "instance": {"version": 17},
      "instance_page_state": {"version": 3},
      "page": {"version": 1},
      "shape": {"version": 3, "subTypeKey": "type", "subTypeVersions": {"group": 0, "embed": 4, "bookmark": 1, "image": 2, "text": 1, "draw": 1, "geo": 7, "line": 0, "note": 4, "frame": 0, "arrow": 1, "highlight": 0, "video": 1}},
      "instance_presence": {"version": 4},
      "pointer": {"version": 1}
    }
  },
  "records": [
    {"id": "document:document", "typeName": "document", "gridSize": 10, "name": "", "meta": {}},
    {"id": "page:page1", "typeName": "page", "name": "Page 1", "index": "a1", "meta": {}}
    /* shapes and arrows go here */
  ]
}

Critical rules:

• document:document and page:page1 records are ALWAYS required.
• All shapes go in the records array after the page record.
• All shapes have "parentId": "page:page1".
• Shape IDs use format "shape:xxx" with unique suffix (e.g., "shape:s1", "shape:a1").
• index values are fractional-index keys. Use "a" + one base-62 character, in order: "a0"–"a9", then "aA"–"aZ", then "aa"–"az" (62 ordered keys — enough for any normal diagram).
• Do not append a second character: "a10" is invalid. And never use a leading "b"/"c" ("b1", "c1", "b0") — those encode a longer integer part, so they are malformed fractional keys and trigger invalidRecords. Stick to the single-character "a*" keys above.

Geo Shape Record

{
  "id": "shape:s1",
  "typeName": "shape",
  "type": "geo",
  "parentId": "page:page1",
  "index": "a1",
  "x": 100,
  "y": 100,
  "rotation": 0,
  "isLocked": false,
  "opacity": 1,
  "meta": {},
  "props": {
    "w": 180,
    "h": 60,
    "geo": "rectangle",
    "color": "blue",
    "labelColor": "black",
    "fill": "semi",
    "dash": "draw",
    "size": "m",
    "font": "draw",
    "text": "API Gateway",
    "align": "middle",
    "verticalAlign": "middle",
    "growY": 0,
    "url": ""
  }
}

Geo Types

All 20 geo values are valid; the above are the useful subset for technical diagrams.

Color Palette

Full palette (13): black, grey, light-violet, violet, blue, light-blue, yellow, orange, green, light-green, light-red, red, white.

Style Options

Arrow Record

{
  "id": "shape:a1",
  "typeName": "shape",
  "type": "arrow",
  "parentId": "page:page1",
  "index": "aG",
  "x": 0,
  "y": 0,
  "rotation": 0,
  "isLocked": false,
  "opacity": 1,
  "meta": {},
  "props": {
    "dash": "draw",
    "size": "m",
    "fill": "none",
    "color": "black",
    "labelColor": "black",
    "bend": 0,
    "start": {
      "type": "binding",
      "boundShapeId": "shape:s1",
      "normalizedAnchor": {"x": 0.5, "y": 1},
      "isExact": false
    },
    "end": {
      "type": "binding",
      "boundShapeId": "shape:s2",
      "normalizedAnchor": {"x": 0.5, "y": 0},
      "isExact": false
    },
    "arrowheadStart": "none",
    "arrowheadEnd": "arrow",
    "text": "",
    "font": "draw"
  }
}

Arrow Connection Rules

• Arrow record x and y are always 0, 0.
• Use "type": "binding" with boundShapeId to connect to a specific shape.
• normalizedAnchor specifies WHERE on the target shape the arrow connects (0–1 range):
  • {x: 0.5, y: 0} = top center
  • {x: 0.5, y: 1} = bottom center
  • {x: 0, y: 0.5} = left center
  • {x: 1, y: 0.5} = right center
  • {x: 0.5, y: 0.5} = center
• Add "text": "label" in arrow props for labeled connections.
• Use "bend": 20 (or -20) for slight curves to avoid overlap with other arrows.
• For dashed/dotted arrows (e.g., async flows, optional links), set "dash": "dashed" or "dotted".
• Set "spline": "cubic" for a smooth curved arrow (default "line" is straight/elbow). Useful for skip connections and back-edges.

Arrowheads

arrowheadStart and arrowheadEnd each accept any of these 9 values (all render in @kitschpatrol/tldraw-cli):

Default arrows use "arrowheadStart": "none", "arrowheadEnd": "arrow". For bidirectional links set both ends to "arrow".

Distributing Arrows on a Shape

When multiple arrows connect to the same shape, assign different normalizedAnchor points to prevent stacking:

Rule: if a shape has N connections on one side, space them evenly (e.g., 3 connections on bottom → x = 0.25, 0.5, 0.75).

Multiple Arrows Between the Same Two Nodes

The anchor-distribution rule above spreads arrows going to different nodes. When N arrows connect the same pair (e.g., bidirectional request/response, or several relationships A↔B), anchors can't separate them — instead spread the bend values symmetrically so the arrows fan out into distinct arcs:

• Pick a max bend amount (≈ 30–60; larger for nodes that are far apart).
• Assign the N arrows bends evenly spaced from −amount to +amount:
  • 2 arrows → bend: -amount, bend: +amount
  • 3 arrows → bend: -amount, 0, +amount
  • General: bend[i] = -amount + i * (2*amount / (N-1)) for i = 0..N-1
• A straight arrow plus a single curved one (bend: 0 and bend: 40) reads cleanly for a request/response pair.

Container & Annotation Shapes

Beyond geo and arrow, two more shape types are useful for technical diagrams.

Frame (labeled container — tiers, subsystems, swimlanes)

A frame is a native rectangular container with a title. Use it to group a tier or subsystem with a visible boundary; stack several frames to approximate swimlanes.

{
  "id": "shape:frame1", "typeName": "shape", "type": "frame",
  "parentId": "page:page1", "index": "a1",
  "x": 60, "y": 60, "rotation": 0, "isLocked": false, "opacity": 1, "meta": {},
  "props": { "w": 360, "h": 220, "name": "Backend Tier", "color": "black" }
}

• props.name is the title shown at the frame's top-left.
• Child shapes set "parentId": "shape:frame1" (not page:page1), and their x/y are relative to the frame's top-left corner, not the page. A child at x: 40, y: 60 sits 40px in and 60px down from the frame's origin.
• Frames render as a clean (non-hand-drawn) rectangle — good for structural grouping. Arrows can still bind across frames normally.

Note (sticky-note annotation / callout)

A note is a sticky note — ideal for TODOs, callouts, and comments layered onto a diagram.

{
  "id": "shape:n1", "typeName": "shape", "type": "note",
  "parentId": "page:page1", "index": "a4",
  "x": 480, "y": 80, "rotation": 0, "isLocked": false, "opacity": 1, "meta": {},
  "props": { "color": "yellow", "size": "m", "text": "TODO: add retry\nlogic here",
    "font": "draw", "align": "middle", "verticalAlign": "middle",
    "growY": 0, "fontSizeAdjustment": 0, "url": "", "scale": 1, "labelColor": "black" }
}

• A note has no w/h — it's a fixed square (~200px) that auto-grows for longer text. Don't add w/h.
• yellow is the classic sticky color; any palette color works.
• Use notes sparingly — for annotations about the diagram, not as primary nodes (use geo for those).

Index Ordering Rules

Indices control z-order (stacking). Use this sequence:

a1, a2, a3, a4, a5, a6, a7, a8, a9,
aA, aB, aC, aD, aE, aF, aG, aH, aI, aJ, aK, aL, aM,
aN, aO, aP, aQ, aR, aS, aT, aU, aV, aW, aX, aY, aZ,
aa, ab, ac, ... az          ← continue here past aZ; never "a10"

• Geo shapes first: a1 through aF (or as many as needed).
• Arrow shapes after: aG, aH, etc.
• Every shape must have a unique index.

Layout Tips

Spacing — scale with complexity:

Sizing boxes to fit labels (do this up front, not in self-check): the draw font is wide. Compute w/h from the label so text never clips. Approximate per-character width and line height for the default draw font:

With padding = 16 on each side:

• w = ceil(longest_line_chars * char_width + 2*padding), then round up to the next multiple of 10.
• h = ceil(num_lines * line_height + 2*padding), rounded up to a multiple of 10.

Example: a size-m box labeled "API Gateway" (11 chars, 1 line) → w ≈ 11*15 + 32 = 197 → 200, h ≈ 28 + 32 = 60. Multi-line labels (with \n) count the longest line for w and the line count for h. Err slightly large — extra padding looks fine, a too-narrow box hard-wraps a word mid-letters.

Why this matters: if a box is too short for its text, tldraw silently grows it taller on render (it sets the shape's growY) — so the box ends up bigger than the h you wrote and collides with whatever you placed below it. Sizing correctly up front keeps growY at 0 and your layout intact. This is the single most common cause of "the diagram looks cramped / boxes overlap" after export.

Routing corridors: between shape rows/columns, leave an extra ~80px empty corridor where arrows can route without crossing other shapes. Never place a shape in a gap that arrows need to traverse.

Grid alignment: snap all x, y, w, h values to multiples of 10 — this matches tldraw's default gridSize: 10 and makes manual editing easier.

General rules:

• Plan the grid before assigning x/y coordinates — sketch node positions mentally first.
• Group related nodes in the same horizontal or vertical band.
• Place heavily-connected "hub" nodes centrally so arrows radiate outward instead of crossing.
• For wide shapes (like an API Gateway spanning multiple downstream services), set w to cover the full span.
• Center-align a child node under its parent (same center x) to avoid diagonal routing.
• Event bus pattern: place the bus (hexagon) in the center of the service row, not below — services on either side reach it with short horizontal arrows (normalizedAnchor.x = 1 left side, 0 right side), eliminating crossings.
• Horizontal connections never cross vertical nodes in the same row; use them for peer-to-peer and publish connections.

Avoiding arrow-shape overlap:

• Before finalizing coordinates, trace each arrow path mentally — if it must cross an unrelated shape, either move the shape or use bend to curve around.
• For tree/hierarchical layouts: assign nodes to layers (rows), connect only between adjacent layers to minimize crossings.
• For star/hub layouts: place the hub center, satellites around it — arrows stay short and radial.

Diagram Type Presets

When the user requests a specific diagram type, apply the matching preset below for shapes, colors, and layout conventions.

Architecture Diagram

Layout: TB or LR by tier count; ≥4 tiers → TB. Hub nodes centered. Spacing scales with complexity (see table above).

Flowchart

Layout: TB, ~200px vertical gap. Decisions branch left/right, then merge back to center. Always label decision branches in the arrow's props.text.

Sequence Diagram

tldraw doesn't have native lifeline shapes. Approximate with:

Layout: LR for actors (200–280px apart), TB for time. Each message is a horizontal arrow between two lifelines at increasing y.

ML / Deep Learning Model Diagram

For neural network architecture diagrams — useful for paper figures and explainers.

Tensor shape annotation: include the dimensions in props.text on a second line. tldraw renders \n literally inside JSON strings, so use a real newline (the JSON encoder will write \n):

"text": "Conv2D\n(B, 64, 32, 32)"

Layout: TB (data flows top → bottom), layers ~150px apart. Skip connections curve around the main stack.

ER Diagram (ERD)

tldraw lacks native table/row shapes. Approximate each entity as a tall rectangle with multi-line text.

Label the arrow with cardinality (e.g., 1..*, 0..1) via props.text.

Layout: TB or grid; entities spaced ≥300px apart to leave room for column lists.

UML Class Diagram

Note: tldraw's triangle/diamond arrowheads are filled, whereas strict UML uses hollow triangles (inheritance) and either filled/hollow diamonds (composition/aggregation). The shapes read correctly for sketches and explainers; for publication-grade UML with hollow heads, drawio-skill (separate skill) is a better fit.

Layout: TB, classes ~250px apart, interfaces above implementations.

Export Commands

# Check CLI version
tldraw --version

# PNG at 2x scale (recommended) — outputs diagram.png in ./
tldraw export diagram.tldr -f png --scale 2 -o ./

# SVG — outputs diagram.svg in ./
tldraw export diagram.tldr -f svg -o ./

# Transparent background
tldraw export diagram.tldr -f png --scale 2 --transparent -o ./

# Dark theme
tldraw export diagram.tldr -f png --scale 2 --dark -o ./

# Custom output directory (e.g. CI artifacts dir) — create if missing, then export there
mkdir -p ./artifacts && tldraw export diagram.tldr -f png --scale 2 -o ./artifacts/

Note: -o is an output directory, not a file path. The output file is named after the input file (diagram.tldr → diagram.png).

Auto-launch after export

Offer to open the .tldr file in the user's default tldraw viewer/editor:

Or upload to https://tldraw.com (drag-and-drop the .tldr file) for browser editing.

Common Mistakes

Fallback Chain

When tools are unavailable, degrade gracefully: