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.
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>
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>
newblacc