Deletions made in the UI were silently lost on page reload because the sync
baseline (lastSyncedElementsRef) was never populated after initial load,
making the delta algorithm unable to detect removed elements. Additionally,
import_scene and restore_snapshot used a non-atomic clear+create pattern
that could permanently lose all canvas data if the batch create failed
after clearing, and duplicate_elements copied stale binding references
pointing to original element IDs instead of remapped duplicates.
🔧 Sync baseline restoration:
- Populate deletion-detection baseline on every server-to-client data path
(page load, delta resync, hello handshake, initial elements broadcast)
- Establish sync version and hash baselines to prevent phantom re-syncs
🛡️ Data-loss prevention:
- Backup current scene before destructive clear in replace-mode operations
- Atomic restore from backup when subsequent batch create fails
- Remap all binding references (start/end IDs, boundElements, containerId)
to new IDs during element duplication
✅ Comprehensive test coverage (154 new tests, 344 total):
- Delta sync flows including deletion persistence and bidirectional sync
- Multi-tenant element/sync/WebSocket isolation
- Arrow binding resolution across all shape types and edge cases
- MCP tool integration covering backup-restore and binding remapping
- Input validation and security boundary testing
- Frontend sync algorithm unit tests reproducing the exact regression
🎯 Eliminates the most critical data-integrity risks: deletions now
persist reliably, destructive operations are rollback-safe, and the
full test suite provides regression coverage for every sync path.
Fix 6 bugs discovered during MCP tool usage:
1. syncToCanvas error handling: Distinguish network errors (return null)
from API errors (re-throw with actual message). Fixes misleading
"HTTP server unavailable" on batch_create_elements.
2. USER_PREFS fallbacks: create_element and batch_create_elements now
apply fontFamily/roughness/fontSize/strokeWidth from preferences.json
when not explicitly provided by the caller.
3. Hello handshake: Frontend sends `hello` on tenant_switched and handles
`hello_ack`. Server resolves projectId from tenantId when absent.
Fixes WS connections being registered under wrong scope.
4. Serialized broadcasts: Add serializedBroadcastWithAck() that queues
broadcasts per tenant/project scope. Prevents race condition where
parallel MCP create_element calls produce overlapping WS messages
that clobber each other in the frontend.
5. Viewport screenshot: get_canvas_screenshot passes captureViewport=true,
frontend captures DOM canvas via toDataURL() instead of exportToBlob()
which always rendered the full scene bounding box.
6. Viewport animate:false: set_viewport uses animate:false for instant
positioning, preventing mid-animation screenshot captures.
Tests: 14 new tests (8 API, 6 WS) + 9 E2E specs covering all fixes.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Implement a complete sync architecture overhaul (12 tasks) replacing the flat
WebSocket broadcast with scoped, acknowledged delivery:
**Backend (server.ts, db.ts, types.ts, index.ts):**
- Scoped connection registry: Map<tenant, Map<project, Set<ClientConnection>>>
- Hello handshake: WS clients identify tenant/project, server responds with scoped elements
- broadcastToScope() replaces global broadcast for element mutations
- broadcastWithAck() waits for browser ACK before returning syncedToCanvas status
- sync_version: monotonic counter per project, stamped on every mutation
- Delta sync v2: POST /api/elements/sync/v2 for incremental sync with version tracking
- GET /api/sync/version endpoint
- Honest syncedToCanvas + canvasStatus in all mutation responses
- Fixed silent try/catch in tenant switch verification
**Frontend (App.tsx):**
- ACK sending after every updateScene() with element verification
- Delta sync v2 integration in syncToBackend()
- Gap detection: triggers resync when sync_version gaps are detected
- lastSyncVersion tracking via refs + localStorage persistence
**Tests (40 new tests, 168 total):**
- db.test.ts: +11 tests for sync_version CRUD, scoping, getChangesSince
- ws.test.ts: +8 tests for hello handshake, scoped broadcast, ACK model
- api.test.ts: +10 tests for sync/v2, sync/version, canvasStatus responses
- helpers.test.ts: +11 tests for isImageElement, normalizeImageElement, restoreBindings
- canvas.spec.ts: +8 e2e tests including full ACK pipeline verification
- Fixed stale tenant state bug in api.test.ts beforeEach
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Font family IDs were duplicated across 5 files (types.ts, setup.ts,
index.ts, SKILL.md, preferences.example.json) with inconsistent
mappings — Comic Shanns was 4 in some places but actually 8 in
Excalidraw source. This caused wrong fonts to render on canvas.
Fix: create src/font-families.json as the canonical font data, import
it in types.ts, and derive all other references from it. Static docs
now point to the JSON file instead of duplicating the mapping.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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>
Existing users who update the npm package often forget to update the agent
skill files, leaving their AI agent working with stale workflow guidance
(sizing rules, color palettes, anti-patterns). The new `update` subcommand
solves this by detecting and updating all skill installations automatically.
🔧 Interactive update wizard:
- Scan all agent directories (Cursor, Claude Code, Codex CLI) across global
and local scopes for existing excalidraw-skill installations
- Batch-update found installations with a single Y/n confirmation
- Offer to install the skill for detected agents that don't have it yet
- Optionally re-apply MCP config (defaults to no for non-breaking updates)
📝 Documentation:
- Rewrite README "Updating" section to lead with the interactive command
- Add collapsible example session showing the update flow
- Retain manual update methods as fallback for each installation path
🎯 Ensures skill files stay in sync with MCP tools across releases,
preventing the subtle drift where new tool capabilities exist but the
agent's workflow guidance doesn't reference them.
- Use fs.realpathSync for entry point detection to fix npx symlink failures
- Add --help and --version CLI flags with explicit process.exit(0)
- Add TTY detection in setup wizard to prevent non-interactive hangs
- Wrap JSON.parse in mergeJsonConfig with try/catch for malformed configs
- Update engines.node to >=20.0.0 to match better-sqlite3 requirements
- Update Dockerfiles from node:18-slim to node:20-slim
- Remove error-swallowing || true from postinstall script
- Replace deprecated windows-build-tools with VS Build Tools link
Establish comprehensive quality infrastructure for a project that previously
had zero tests, enabling confident refactoring and community contributions
with automated guardrails. Port upstream enhancements for font normalization,
image element support, and arrow binding preservation.
🏗️ Testing infrastructure:
- Unit tests for SQLite persistence layer and element validation helpers
- Integration tests for REST API, WebSocket broadcast, and arrow binding
- E2E tests with Playwright for canvas rendering and real-time sync
- Vitest + Playwright configuration with proper isolation
👷 CI/CD pipeline:
- Auto-versioning from conventional commits on push to main
- Auto-publish to NPM and Docker Hub on GitHub release
- Matrix testing across Node 18/20/22 with pinned dependencies
- Docker health check with diagnostic logging on failure
- Preserve rollup status checks for branch protection gates
📦 Developer experience:
- Interactive setup wizard for first-time configuration
- Canvas clear confirmation and scene description tools
- Frontend helpers extracted for testability
🔧 Upstream feature ports:
- Font family normalization (string names to numeric IDs)
- Image element support with file management API
- Arrow binding preservation through server round-trips
- Vite config fix for font subsetting worker chunk names
- Idempotent database initialization for standalone Docker mode
🐛 Docker fixes:
- Set EXCALIDRAW_DB_PATH in both Dockerfiles to writable /app/data/
- Make initDb() idempotent and closeDb() reset-safe for test isolation
🎯 Provides the safety net needed for rapid iteration — every PR is
validated across 120 test cases before merge, and releases are fully
automated from commit to published package.
Co-authored-by: sanjibdevnathlabs <devnath.sanjib@gmail.com>
Replace in-memory storage with SQLite (WAL mode), add workspace-based
multi-tenancy with auto-detection via server.listRoots(), and embed the
canvas server into the MCP process for single-process operation.
🔧 Core enhancements:
- SQLite persistence with versioning, element history, and search
- Multi-tenancy: isolated canvases per workspace (SHA-256 tenant IDs)
- Embedded canvas lifecycle (single node process starts MCP + canvas)
- Auto-sync with 3s debounce and manual override toggle
- Configurable canvas port via CANVAS_PORT env var
- 6 new MCP tools (search, history, tenants, projects)
- Workspace switcher UI with dropdown search
- Sync normalization to prevent bound-text breakage on reload
🐳 Docker & CI improvements:
- BuildKit cache mounts for faster npm installs across builds
- Skip native compilation in frontend-builder stage (--ignore-scripts)
- Build only linux/amd64 on PRs, multi-arch on push to main
- Docker Hub registry with proper build tools for better-sqlite3
- CI and Docker status check gates (github/ci-status-check, github/docker-build-check)
📦 Package & publishing:
- Renamed to @sanjibdevnath/mcp-excalidraw-local (v3.0.0)
- Updated npm-publish workflow for scoped package
- Updated bin entry, keywords, and files list
📝 Documentation:
- README with UI screenshots, architecture diagram, and full feature docs
- Updated agent skill with 32-tool cheatsheet and workflow playbooks
- Fork attribution and upstream comparison table
Co-authored-by: Cursor <cursoragent@cursor.com>
* feat: enhance Excalidraw MCP with advanced canvas toolkit features
- Rename skill to `excalidraw-skill` with expanded playbook and cheatsheet.
- Add new MCP tools for iterative refinement: `describe_scene` and `get_canvas_screenshot`.
- Implement layout tools (`align_elements`, `distribute_elements`) and `duplicate_elements`.
- Add file I/O support for `.excalidraw` JSON and image export (PNG/SVG).
- Introduce named snapshots for canvas state management.
- Add server-side element CRUD and WebSocket handlers for real-time sync.
- Normalize `points` format for arrows and lines.
* docs: update README with v2.0 features and official MCP comparison
* feat: implement arrow binding and edge-to-edge routing
* fix: enhance security with path sanitization and improve export error handling
* feat: add viewport control, design guide, and excalidraw.com URL export
* feat: enhance excalidraw.com export with proper scene formatting and labels
- Updated package.json to point to compiled TypeScript files in the dist directory.
- Improved TypeScript configuration with stricter type checks and removed JavaScript support.
- Migrated frontend entry point to TypeScript and added a new App component with enhanced functionality.
- Implemented a new server structure with TypeScript, including WebSocket support and improved element management.
- Updated README to reflect changes in architecture and usage instructions.
- Added comprehensive type definitions for Excalidraw elements and server responses.
