feat(workspace): implement Yjs CRDT real-time collaborative editing (resolves FLAW-01)

internal/storage/sqlite_test.go

@@ -683,3 +683,62 @@ func TestDatabaseFirstWorkspaceArchitecture(t *testing.T) {
 	}
 }
 
+func TestDocumentCRDTState(t *testing.T) {
+	tmpDir := t.TempDir()
+	dbPath := filepath.Join(tmpDir, "crdt_test.db")
+
+	store, err := NewStore(dbPath)
+	if err != nil {
+		t.Fatalf("NewStore failed: %v", err)
+	}
+	defer store.Close()
+
+	user, err := store.CreateUser("crdt@example.com", "hash", "CRDT User", "member")
+	if err != nil {
+		t.Fatalf("CreateUser failed: %v", err)
+	}
+
+	doc, err := store.CreateDocument(user.ID, "", "CRDT Test Doc", "📝", "", nil, nil, false)
+	if err != nil {
+		t.Fatalf("CreateDocument failed: %v", err)
+	}
+
+	// 1. Initial CRDT state is empty
+	state, updates, err := store.GetDocumentCRDTState(doc.ID)
+	if err != nil {
+		t.Fatalf("GetDocumentCRDTState failed: %v", err)
+	}
+	if len(state) != 0 || len(updates) != 0 {
+		t.Fatalf("expected empty CRDT state, got state=%d updates=%d", len(state), len(updates))
+	}
+
+	// 2. Append incremental updates
+	u1 := []byte{1, 2, 3, 4}
+	u2 := []byte{5, 6, 7, 8}
+	if err := store.AppendDocumentCRDTUpdate(doc.ID, u1, user.ID); err != nil {
+		t.Fatalf("AppendDocumentCRDTUpdate 1 failed: %v", err)
+	}
+	if err := store.AppendDocumentCRDTUpdate(doc.ID, u2, user.ID); err != nil {
+		t.Fatalf("AppendDocumentCRDTUpdate 2 failed: %v", err)
+	}
+
+	_, updatesAfter, err := store.GetDocumentCRDTState(doc.ID)
+	if err != nil || len(updatesAfter) != 2 {
+		t.Fatalf("expected 2 updates, got %d (err: %v)", len(updatesAfter), err)
+	}
+
+	// 3. Compact snapshot state
+	snapshot := []byte{99, 100, 101}
+	if err := store.SaveDocumentCRDTState(doc.ID, snapshot, user.ID); err != nil {
+		t.Fatalf("SaveDocumentCRDTState failed: %v", err)
+	}
+
+	stateAfter, updatesAfterCompact, err := store.GetDocumentCRDTState(doc.ID)
+	if err != nil {
+		t.Fatalf("GetDocumentCRDTState after compact failed: %v", err)
+	}
+	if len(stateAfter) != 3 || len(updatesAfterCompact) != 0 {
+		t.Fatalf("expected compacted state of length 3 and 0 updates, got state=%d updates=%d", len(stateAfter), len(updatesAfterCompact))
+	}
+}
+