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Author SHA1 Message Date
sanjibdevnathlabs-release-bot[bot] aa29ddbf13 chore(release): v1.4.0 2026-03-17 09:02:29 +00:00
sanjibdevnathlabsandClaude Opus 4.6 9114e81f02 feat(skill): add user-configurable diagram preferences system
Add a preference system that lets users configure default font, roughness,
fontSize, and strokeWidth — with three scopes (session/folder/global).

Skill layer (Step 1 in SKILL.md):
- Reads .claude/excalidraw-preferences.json (folder) then
  ~/.claude/skills/excalidraw-skill/preferences.json (global)
- If neither exists, prompts user interactively on first use
- Session-only scope keeps preferences in-memory without saving

Server layer (index.ts):
- loadPreferences() reads the same files at startup
- Replaces hardcoded fontFamily ?? 1 with USER_PREFS.fontFamily
- Folder-level preferences override global; user values override both

Also ships preferences.example.json as a template (preferences.json
is gitignored).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-03-17 14:27:34 +05:30
sanjibdevnathlabs-release-bot[bot] fac1c7a267 chore(release): v1.3.0 2026-03-13 18:19:16 +00:00
sanjibdevnathlabs 9311561227 feat(skill): add auto-triggering for excalidraw-skill via CLAUDE.md directives
The excalidraw-skill was not being auto-invoked when users prompted
Claude to draw diagrams, despite being installed. Claude would call
Excalidraw MCP tools directly, bypassing the skill's critical sizing
formulas and verification workflow — producing broken diagrams with
invisible arrows, truncated text, and overlapping elements. The root
cause is that Claude Code's skill system is advisory: when direct MCP
tools or built-in Bash instructions are available, Claude skips skill
consultation entirely.

🔧 Skill description rewrite:
- Lead with "MANDATORY prerequisite" to assert priority over raw MCP tools
- Add user-intent trigger keywords (draw, visualize, sketch, diagram)
- Name specific consequences of skipping the skill
- List common diagram types for semantic matching

🏗️ Setup/update auto-directives:
- Write marked CLAUDE.md sections during skill install and update
- Write Cursor .mdc rules with alwaysApply for Cursor users
- Use HTML comment markers for idempotent append-or-replace on updates
- Non-fatal directive writing — skill installs even if directive fails

🎯 Two-layer defense ensures reliable skill triggering: the description
catches semantic matching, while the CLAUDE.md directive provides an
authoritative instruction that Claude cannot deprioritize in favor of
raw tool access.
2026-03-13 23:46:59 +05:30
8 changed files with 267 additions and 12 deletions
+3
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@@ -15,6 +15,9 @@ public/dist/
.cursor/
.claude/
# User preferences (only the example ships)
skills/excalidraw-skill/preferences.json
# Development artifacts
*.excalidraw
+2 -2
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@@ -1,12 +1,12 @@
{
"name": "@sanjibdevnath/mcp-excalidraw-local",
"version": "1.2.1",
"version": "1.4.0",
"lockfileVersion": 3,
"requires": true,
"packages": {
"": {
"name": "@sanjibdevnath/mcp-excalidraw-local",
"version": "1.2.1",
"version": "1.4.0",
"hasInstallScript": true,
"license": "MIT",
"dependencies": {
+1 -1
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@@ -1,6 +1,6 @@
{
"name": "@sanjibdevnath/mcp-excalidraw-local",
"version": "1.2.1",
"version": "1.4.0",
"description": "Fully local MCP server for Excalidraw with SQLite persistence, multi-tenancy, auto-sync, real-time canvas, and 32 tools",
"main": "dist/index.js",
"type": "module",
+74 -1
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@@ -1,6 +1,6 @@
---
name: excalidraw-skill
description: Programmatic canvas toolkit for creating, editing, and refining Excalidraw diagrams via MCP tools (32 tools) or REST API with real-time canvas sync, multi-tenant workspace isolation, SQLite persistence, project management, full-text search, and element version history. Use when an agent needs to draw or lay out diagrams on a live canvas, iteratively refine diagrams using screenshots, manage workspaces/tenants and projects, export/import .excalidraw files or PNG/SVG images, search elements, view change history, save/restore canvas snapshots, or perform element-level CRUD. Canvas server port is configurable via CANVAS_PORT env var (default 3000).
description: MANDATORY prerequisite for ALL Excalidraw MCP tool usage. Read this skill BEFORE calling any Excalidraw tool (batch_create_elements, create_element, create_from_mermaid, update_element, etc.) — without this skill's sizing formulas, two-batch ordering (shapes first, arrows second), and write-check-review verification cycle, diagrams will have invisible arrows, truncated text, and overlapping elements. Use whenever the user asks to draw, create, visualize, sketch, or diagram anything — flowcharts, architecture diagrams, system designs, org charts, sequence flows, decision trees, network topologies, ER diagrams, mind maps, or any visual on Excalidraw canvas. Also covers diagram refinement, PNG/SVG export, project/workspace management, and all canvas interactions.
---
# Excalidraw Skill
@@ -15,6 +15,79 @@ Run these checks **in order**:
See `references/cheatsheet.md` for the full MCP-vs-REST mapping and REST API gotchas.
## Step 1: Load User Preferences
Before creating any elements, load the user's diagram preferences. These control default font, roughness, stroke width, etc.
### Preference Resolution Order (most specific wins)
| Priority | Scope | Location | Persists |
|----------|-------|----------|----------|
| 1 (highest) | Session | In-memory (set via prompt during this conversation) | No — current session only |
| 2 | Folder | `.claude/excalidraw-preferences.json` in the current project root | Yes — per-project |
| 3 | Global | `~/.claude/skills/excalidraw-skill/preferences.json` | Yes — all projects |
| 4 (lowest) | Hardcoded | Server defaults (fontFamily: 1, roughness: 0, fontSize: 20, strokeWidth: 2) | — |
### How to Load
1. **Check folder-level first**: Read `.claude/excalidraw-preferences.json` from the current working directory (or project root). If it exists and has `defaults`, use those values.
2. **Fall back to global**: Read `~/.claude/skills/excalidraw-skill/preferences.json`. If it exists and has `defaults`, use those values.
3. **If neither exists** → run the **First-Time Setup** prompt below.
4. **Merge**: Folder preferences override global; global overrides hardcoded. Only override fields that are explicitly set.
### First-Time Setup (Interactive)
If no preferences file exists at either location, **prompt the user before drawing anything**:
> **Excalidraw Preferences Setup**
>
> I don't have any saved diagram preferences yet. Let me set up your defaults so every diagram looks the way you want.
Ask these questions (use `AskUserQuestion` tool if available, otherwise ask inline):
1. **Font family** — Which font for all text?
- Excalifont (hand-drawn) = 1
- Helvetica (sans-serif) = 2
- Cascadia (monospace) = 3
- Comic Shanns = 4
- Nunito = 6
- Lilita One = 7
2. **Roughness** — Diagram style?
- Clean/professional (roughness: 0) — recommended
- Hand-drawn sketch (roughness: 1)
- Very rough (roughness: 2)
3. **Scope** — Where to save?
- **This session only** — don't save to disk, just use for this conversation
- **This project** — save to `.claude/excalidraw-preferences.json` in project root
- **Global (all projects)** — save to `~/.claude/skills/excalidraw-skill/preferences.json`
Then save the preferences JSON to the chosen location:
```json
{
"defaults": {
"fontFamily": <user_choice>,
"fontSize": 20,
"roughness": <user_choice>,
"strokeWidth": 2
}
}
```
For session-only scope, just hold the values in memory and apply them to every element in this conversation.
### Applying Preferences
Once loaded, apply `defaults` to **every element** that supports the property:
- `fontFamily` → all text-containing elements (text, rectangles with labels, diamonds, ellipses, arrows with labels)
- `fontSize` → text elements and labels (unless the element explicitly overrides it)
- `roughness` → all elements
- `strokeWidth` → arrows and lines
User-specified values in individual element calls always override preferences.
## Core Principles (Read Before Any Diagram)
These principles were learned through extensive iterative use. Violating them produces bad diagrams.
@@ -0,0 +1,18 @@
{
"_comment": "Excalidraw MCP user preferences. Copy to preferences.json to activate.",
"_fontReference": {
"1": "Excalifont (hand-drawn)",
"2": "Helvetica (sans-serif)",
"3": "Cascadia (monospace)",
"4": "Comic Shanns",
"5": "Liberation Sans",
"6": "Nunito",
"7": "Lilita One"
},
"defaults": {
"fontFamily": 1,
"fontSize": 20,
"roughness": 0,
"strokeWidth": 2
}
}
@@ -94,16 +94,15 @@
|---------|----------------|-----------------|
| Shape labels | `"text": "My Label"` (auto-converts) | `"label": {"text": "My Label"}` |
| Arrow binding | `"startElementId": "id"` / `"endElementId": "id"` | `"start": {"id": "id"}` / `"end": {"id": "id"}` |
| `fontFamily` | String `"1"` or omit | String `"1"` or omit (never a number) |
| `fontFamily` | Number or string — use value from user preferences (see Step 1 in SKILL.md) | String — use value from user preferences |
| Tenant scoping | Auto (uses active tenant) | Include `X-Tenant-Id` header on every request |
### Element Creation Best Practices
- **Always set `roughness: 0`** for clean, professional diagrams (default is hand-drawn).
- **Always set `strokeWidth: 2`** on arrows for visibility.
- **Always apply user preferences** — load from Step 1 in SKILL.md and apply `fontFamily`, `roughness`, `fontSize`, `strokeWidth` to every element.
- **Create shapes first, arrows second** (two separate `batch_create_elements` calls).
- **Assign custom `id`** to every shape so arrows can reference it.
- **Size shapes for their text** — Virgil font is ~30% wider than standard. Use sizing formulas from SKILL.md.
- **Size shapes for their text** — use sizing formulas from SKILL.md.
- `points` accepts both `[[x,y]]` tuples and `[{x,y}]` objects — normalized automatically.
- **Curved arrows**: Use `"roundness": {"type": 2}` with 3+ points. **Elbowed arrows**: Use `"elbowed": true`.
+45 -4
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@@ -65,6 +65,47 @@ const CANVAS_PORT = process.env.CANVAS_PORT || process.env.PORT || '3000';
const EXPRESS_SERVER_URL = process.env.EXPRESS_SERVER_URL || `http://localhost:${CANVAS_PORT}`;
const ENABLE_CANVAS_SYNC = true;
// User preferences for element defaults (font, roughness, etc.)
// Resolution: folder-level .claude/excalidraw-preferences.json > global ~/.claude/skills/excalidraw-skill/preferences.json > hardcoded
interface ExcalidrawPreferences {
fontFamily: number;
fontSize: number;
roughness: number;
strokeWidth: number;
}
const HARDCODED_DEFAULTS: ExcalidrawPreferences = {
fontFamily: 1,
fontSize: 20,
roughness: 0,
strokeWidth: 2,
};
function loadPreferences(): ExcalidrawPreferences {
const locations = [
path.join(process.cwd(), '.claude', 'excalidraw-preferences.json'),
path.join(process.env.HOME || '~', '.claude', 'skills', 'excalidraw-skill', 'preferences.json'),
];
for (const loc of locations) {
try {
if (fs.existsSync(loc)) {
const raw = JSON.parse(fs.readFileSync(loc, 'utf-8'));
if (raw?.defaults) {
logger.info(`Loaded user preferences from ${loc}`);
return { ...HARDCODED_DEFAULTS, ...raw.defaults };
}
}
} catch (e) {
logger.warn(`Failed to read preferences from ${loc}: ${e}`);
}
}
return HARDCODED_DEFAULTS;
}
const USER_PREFS = loadPreferences();
// One-time tokens for clear_canvas confirmation (token → expiry timestamp)
const pendingClearTokens = new Map<string, { expiresAt: number; elementCount: number }>();
const CLEAR_TOKEN_TTL_MS = 120_000; // 2 minutes
@@ -2199,8 +2240,8 @@ server.setRequestHandler(CallToolRequestSchema, async (request: CallToolRequest)
if (el.type === 'text') {
base.text = text ?? '';
base.originalText = text ?? '';
base.fontSize = rest.fontSize ?? 20;
base.fontFamily = rest.fontFamily ?? 1;
base.fontSize = rest.fontSize ?? USER_PREFS.fontSize;
base.fontFamily = rest.fontFamily ?? USER_PREFS.fontFamily;
base.textAlign = rest.textAlign ?? 'center';
base.verticalAlign = rest.verticalAlign ?? 'middle';
base.autoResize = rest.autoResize ?? true;
@@ -2294,8 +2335,8 @@ server.setRequestHandler(CallToolRequestSchema, async (request: CallToolRequest)
locked: false,
text: labelText,
originalText: labelText,
fontSize: isArrow ? 14 : (rest.fontSize ?? 16),
fontFamily: rest.fontFamily ?? 1,
fontSize: isArrow ? 14 : (rest.fontSize ?? USER_PREFS.fontSize),
fontFamily: rest.fontFamily ?? USER_PREFS.fontFamily,
textAlign: 'center',
verticalAlign: 'middle',
autoResize: true,
+121
View File
@@ -57,6 +57,11 @@ interface AgentDef {
mcpConfigPath?: string;
mcpCliRemove?: string;
mcpCliCommand?: string;
instructionConfig?: {
global: string;
local: string;
format: 'claude-md' | 'cursor-mdc';
};
}
function getAgents(): AgentDef[] {
@@ -71,6 +76,11 @@ function getAgents(): AgentDef[] {
},
mcpConfigType: 'json-file',
mcpConfigPath: path.join(home, '.cursor', 'mcp.json'),
instructionConfig: {
global: path.join(home, '.cursor', 'rules', 'excalidraw.mdc'),
local: path.join(process.cwd(), '.cursor', 'rules', 'excalidraw.mdc'),
format: 'cursor-mdc',
},
},
{
name: 'Claude Code',
@@ -82,6 +92,11 @@ function getAgents(): AgentDef[] {
mcpConfigType: 'cli-command',
mcpCliRemove: 'claude mcp remove excalidraw-canvas --scope user',
mcpCliCommand: 'claude mcp add excalidraw-canvas --scope user -e CANVAS_PORT=3000 -- npx -y @sanjibdevnath/mcp-excalidraw-local@latest',
instructionConfig: {
global: path.join(home, '.claude', 'CLAUDE.md'),
local: path.join(process.cwd(), 'CLAUDE.md'),
format: 'claude-md',
},
},
{
name: 'Codex CLI',
@@ -226,6 +241,17 @@ async function phaseSkillInstall(rl: readline.Interface): Promise<void> {
fs.mkdirSync(destDir, { recursive: true });
copyDirSync(skillSource, destDir);
ok(`Installed to ${destDir}`);
// Write instruction directive to ensure skill auto-triggers
if (agent.instructionConfig) {
const instrPath = agent.instructionConfig[scope];
try {
writeInstructionDirective(instrPath, agent.instructionConfig.format);
ok(`Skill directive added to ${instrPath}`);
} catch (instrErr) {
warn(`Could not write directive to ${instrPath}: ${(instrErr as Error).message}`);
}
}
} catch (err) {
fail(`Failed to install to ${destDir}: ${(err as Error).message}`);
}
@@ -245,6 +271,79 @@ function copyDirSync(src: string, dest: string): void {
}
}
// ── Instruction Directives ──────────────────────────────────
const DIRECTIVE_MARKER_START = '<!-- excalidraw-mcp:start -->';
const DIRECTIVE_MARKER_END = '<!-- excalidraw-mcp:end -->';
const EXCALIDRAW_DIRECTIVE_BODY =
'When Excalidraw MCP tools are available (batch_create_elements, create_element, ' +
'create_from_mermaid, etc.), ALWAYS invoke the `/excalidraw-skill` skill FIRST ' +
'before calling any Excalidraw tool. The skill contains essential sizing formulas, ' +
'batch ordering rules (shapes first, arrows second), and a mandatory ' +
'write-check-review verification cycle. Using Excalidraw tools without consulting ' +
'this skill produces broken diagrams — invisible arrows, truncated text, ' +
'overlapping elements.';
function buildClaudeMdSection(): string {
return [
DIRECTIVE_MARKER_START,
'## Excalidraw Canvas — Skill Directive',
'',
EXCALIDRAW_DIRECTIVE_BODY,
DIRECTIVE_MARKER_END,
].join('\n');
}
function buildCursorMdc(): string {
return [
'---',
'description: Always consult excalidraw-skill before using Excalidraw MCP tools',
'globs:',
'alwaysApply: true',
'---',
'',
'## Excalidraw Canvas — Skill Directive',
'',
EXCALIDRAW_DIRECTIVE_BODY,
'',
].join('\n');
}
function writeInstructionDirective(filePath: string, format: 'claude-md' | 'cursor-mdc'): void {
const dir = path.dirname(filePath);
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir, { recursive: true });
}
if (format === 'cursor-mdc') {
// Cursor .mdc files are standalone — write/overwrite the whole file
fs.writeFileSync(filePath, buildCursorMdc(), 'utf-8');
return;
}
// For claude-md: append or replace the marked section
let content = '';
if (fs.existsSync(filePath)) {
content = fs.readFileSync(filePath, 'utf-8');
}
const section = buildClaudeMdSection();
const startIdx = content.indexOf(DIRECTIVE_MARKER_START);
const endIdx = content.indexOf(DIRECTIVE_MARKER_END);
if (startIdx !== -1 && endIdx !== -1) {
// Replace existing section
content = content.slice(0, startIdx) + section + content.slice(endIdx + DIRECTIVE_MARKER_END.length);
} else {
// Append with spacing
const trimmed = content.trimEnd();
content = trimmed + (trimmed ? '\n\n' : '') + section + '\n';
}
fs.writeFileSync(filePath, content, 'utf-8');
}
// ── Phase 3: MCP Configuration ──────────────────────────────
async function phaseMcpConfig(rl: readline.Interface): Promise<void> {
@@ -450,6 +549,17 @@ export async function runUpdate(): Promise<void> {
copyDirSync(skillSource, inst.path);
ok(`Updated ${inst.agent.name} (${inst.scope}) — ${inst.path}`);
updated++;
// Update instruction directive
if (inst.agent.instructionConfig) {
const instrPath = inst.agent.instructionConfig[inst.scope];
try {
writeInstructionDirective(instrPath, inst.agent.instructionConfig.format);
ok(`Skill directive updated in ${instrPath}`);
} catch (instrErr) {
warn(`Could not update directive in ${instrPath}: ${(instrErr as Error).message}`);
}
}
} catch (err) {
fail(`Failed to update ${inst.path}: ${(err as Error).message}`);
}
@@ -484,6 +594,17 @@ export async function runUpdate(): Promise<void> {
fs.mkdirSync(destDir, { recursive: true });
copyDirSync(skillSource, destDir);
ok(`Installed to ${destDir}`);
// Write instruction directive
if (agent.instructionConfig) {
const instrPath = agent.instructionConfig[scope];
try {
writeInstructionDirective(instrPath, agent.instructionConfig.format);
ok(`Skill directive added to ${instrPath}`);
} catch (instrErr) {
warn(`Could not write directive to ${instrPath}: ${(instrErr as Error).message}`);
}
}
} catch (err) {
fail(`Failed to install to ${destDir}: ${(err as Error).message}`);
}