fix: resolveSnippetRef now checks session cache before querying backend (#509)

Snippets created earlier in the same script were not visible to pages
created later in the same execution session: resolveSnippetRef always
queried the backend, which doesn't see uncommitted documents.

Added the same cache-first lookup that resolveMicroflow and resolvePageRef
already use: check ctx.Cache.createdSnippets before falling through to the
backend ListSnippets call. This makes forward snippet references within a
single script work regardless of declaration order.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ako

mdl/executor/cmd_pages_builder_input.go

@@ -83,6 +83,19 @@ func (pb *pageBuilder) resolveSnippetRef(snippetRef string) (model.ID, error) {
 		snippetName = snippetRef
 	}
 
+	// First, check if the snippet was created during this session
+	// (not yet visible via reader)
+	if pb.execCache != nil && pb.execCache.createdSnippets != nil {
+		if info, ok := pb.execCache.createdSnippets[snippetRef]; ok {
+			return info.ID, nil
+		}
+		if moduleName != "" {
+			if info, ok := pb.execCache.createdSnippets[moduleName+"."+snippetName]; ok {
+				return info.ID, nil
+			}
+		}
+	}
+
 	snippets, err := pb.backend.ListSnippets()
 	if err != nil {
 		return "", err

mdl/executor/cmd_pages_builder_input_test.go

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package executor
+
+import (
+	"testing"
+
+	"github.com/mendixlabs/mxcli/mdl/backend/mock"
+	"github.com/mendixlabs/mxcli/model"
+	"github.com/mendixlabs/mxcli/sdk/pages"
+)
+
+// TestResolveSnippetRef_FromCache verifies that resolveSnippetRef finds snippets
+// that were created earlier in the same session (before the backend sees them).
+// Regression test for issue #509.
+func TestResolveSnippetRef_FromCache(t *testing.T) {
+	mod := mkModule("MyModule")
+
+	mb := &mock.MockBackend{
+		IsConnectedFunc: func() bool { return true },
+		// Backend returns nothing — snippet only exists in session cache
+		ListSnippetsFunc: func() ([]*pages.Snippet, error) { return nil, nil },
+	}
+
+	snpID := model.ID("snp-session-1")
+	cache := &executorCache{
+		createdSnippets: map[string]*createdSnippetInfo{
+			"MyModule.NavMenu": {
+				ID:         snpID,
+				Name:       "NavMenu",
+				ModuleName: "MyModule",
+			},
+		},
+	}
+
+	h := mkHierarchy(mod)
+	withContainer(h, mod.ID, mod.ID)
+
+	pb := &pageBuilder{
+		backend:   mb,
+		execCache: cache,
+	}
+	pb.execCache.hierarchy = h
+
+	// Should resolve from cache, not from backend
+	id, err := pb.resolveSnippetRef("MyModule.NavMenu")
+	if err != nil {
+		t.Fatalf("resolveSnippetRef returned error: %v", err)
+	}
+	if id != snpID {
+		t.Fatalf("expected ID %q, got %q", snpID, id)
+	}
+}
+
+// TestResolveSnippetRef_NotFoundInCache verifies that when a snippet is absent
+// from both cache and backend, a "not found" error is returned.
+func TestResolveSnippetRef_NotFoundInCache(t *testing.T) {
+	mb := &mock.MockBackend{
+		IsConnectedFunc: func() bool { return true },
+		ListSnippetsFunc: func() ([]*pages.Snippet, error) { return nil, nil },
+		ListModulesFunc:  func() ([]*model.Module, error) { return nil, nil },
+	}
+
+	cache := &executorCache{
+		createdSnippets: map[string]*createdSnippetInfo{},
+	}
+
+	mod := mkModule("MyModule")
+	h := mkHierarchy(mod)
+	withContainer(h, mod.ID, mod.ID)
+
+	pb := &pageBuilder{
+		backend:   mb,
+		execCache: cache,
+	}
+	pb.execCache.hierarchy = h
+
+	_, err := pb.resolveSnippetRef("MyModule.Missing")
+	if err == nil {
+		t.Fatal("expected error for missing snippet, got nil")
+	}
+}