feat(server): persist renderContent texture and cover it in asset lifecycle

Add an optional renderContent field to canvas nodes across the go-zero API
type, domain node, SQLC models/queries, PostgreSQL schema, and mappers so a
lightweight transparent-WebP display texture persists alongside the original
content. Prefer renderContent for project thumbnails and main-canvas
previews, and treat both content and renderContent as protected/deletable
asset URLs during canvas asset cleanup. Extend round-trip coverage.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/API.md

@@ -539,7 +539,7 @@ Returns `{ "code": 0, "msg": "success", "data": { "status": "done" } }` or the c
 
 Saves canvas layout changes with a Lovart-style lightweight payload. The frontend posts to `/api/canva/project/saveProject`; `/api/projects/:id/canvas` remains as a compatibility route. The `canvas` value is a `SHAKKERDATA://` gzip+base64 encoded snapshot containing viewport, nodes, and connections. Legacy uncompressed `{ "viewport": ..., "nodes": ..., "connections": ... }` payloads are still accepted.
 
-Canvas nodes may include optional `semanticContext`. CAD source nodes use `layerRole: "cad-vector"`; non-destructive crop siblings use `layerRole: "cad-crop"` and carry crop-specific context. PostgreSQL persists the field in `canvas_nodes.semantic_context`.
+Canvas nodes may include optional `semanticContext` and `renderContent`. CAD source nodes use `layerRole: "cad-vector"`; non-destructive crop siblings use `layerRole: "cad-crop"` and carry crop-specific context. `content` remains the original SVG/CAD-derived source used by crop, download, and model-reference flows, while `renderContent` is an optional transparent WebP texture used only for fast canvas display. PostgreSQL persists both fields.
 
 When a canvas image node disappears from the saved node list, its backing OSS asset is queued for asynchronous deletion after the canvas save succeeds.
 

server/img_infinite_canvas.api

@@ -238,6 +238,7 @@ type CanvasNode {
 	Width               float64       `json:"width"`
 	Height              float64       `json:"height"`
 	Content             string        `json:"content"`
+	RenderContent       string        `json:"renderContent,optional"`
 	Tone                string        `json:"tone"`
 	Status              string        `json:"status"`
 	ParentId            string        `json:"parentId,optional"`

server/internal/application/asset_cleanup.go

@@ -189,18 +189,16 @@ func deletedCanvasAssetURLs(previous []design.Node, next []design.Node, messages
 	seen := make(map[string]struct{})
 	var deleted []string
 	for _, node := range previous {
-		url := nodeAssetURL(node)
+		for _, url := range nodeAssetURLs(node) {
-		if url == "" {
+			if assetURLSetContains(protectedURLs, url) {
-			continue
+				continue
+			}
+			if _, ok := seen[url]; ok {
+				continue
+			}
+			seen[url] = struct{}{}
+			deleted = append(deleted, url)
 		}
-		if assetURLSetContains(protectedURLs, url) {
-			continue
-		}
-		if _, ok := seen[url]; ok {
-			continue
-		}
-		seen[url] = struct{}{}
-		deleted = append(deleted, url)
 	}
 	return deleted
 }
@@ -220,7 +218,9 @@ func projectAssetURLs(project design.Project) []string {
 		urls = append(urls, url)
 	}
 	for _, node := range project.Nodes {
-		add(nodeAssetURL(node))
+		for _, url := range nodeAssetURLs(node) {
+			add(url)
+		}
 	}
 	for _, url := range canvasSnapshotAssetURLs(project.Canvas) {
 		add(url)
@@ -267,9 +267,7 @@ func canvasSnapshotAssetURLs(canvas string) []string {
 	}
 	urls := make([]string, 0, len(snapshot.Nodes))
 	for _, node := range snapshot.Nodes {
-		if url := nodeAssetURL(node); url != "" {
+		urls = append(urls, nodeAssetURLs(node)...)
-			urls = append(urls, url)
-		}
 	}
 	return urls
 }
@@ -277,22 +275,26 @@ func canvasSnapshotAssetURLs(canvas string) []string {
 func canvasAssetURLSet(nodes []design.Node) map[string]struct{} {
 	items := make(map[string]struct{})
 	for _, node := range nodes {
-		if url := nodeAssetURL(node); url != "" {
+		for _, url := range nodeAssetURLs(node) {
 			addAssetURLKeys(items, url)
 		}
 	}
 	return items
 }
 
-func nodeAssetURL(node design.Node) string {
+func nodeAssetURLs(node design.Node) []string {
 	if node.Type != design.NodeTypeImage && node.Type != design.NodeTypeFrame {
-		return ""
+		return nil
 	}
-	content := strings.TrimSpace(node.Content)
+	urls := make([]string, 0, 2)
-	if content == "" || strings.HasPrefix(content, "data:image/") || !isGeneratedImageContent(content) {
+	for _, content := range []string{node.Content, node.RenderContent} {
-		return ""
+		content = strings.TrimSpace(content)
+		if content == "" || strings.HasPrefix(content, "data:image/") || !isGeneratedImageContent(content) {
+			continue
+		}
+		urls = append(urls, content)
 	}
-	return content
+	return normalizeAssetURLs(urls)
 }
 
 func promptMessageAssetURLs(content string) []string {

server/internal/application/asset_cleanup_test.go

@@ -63,7 +63,7 @@ func TestDeleteProjectEnqueuesAssetCleanupJobWhenJobQueueIsConfigured(t *testing
 		Status:    design.StatusReady,
 		UpdatedAt: time.Now(),
 		Nodes: []design.Node{
-			{ID: "image-1", Type: design.NodeTypeImage, Content: "http://localhost:19000/canvas-assets/a.png", Status: "success"},
+			{ID: "image-1", Type: design.NodeTypeImage, Content: "http://localhost:19000/canvas-assets/a.svg", RenderContent: "http://localhost:19000/canvas-assets/a.render.webp", Status: "success"},
 		},
 	}
 	if err := repo.Save(ctx, project); err != nil {
@@ -78,7 +78,7 @@ func TestDeleteProjectEnqueuesAssetCleanupJobWhenJobQueueIsConfigured(t *testing
 		t.Fatalf("expected one cleanup job, got %#v", queue.jobs)
 	}
 	job := queue.jobs[0]
-	if job.Kind != design.JobAssetCleanup || len(job.PublicURLs) != 1 || job.PublicURLs[0] != "http://localhost:19000/canvas-assets/a.png" {
+	if job.Kind != design.JobAssetCleanup || len(job.PublicURLs) != 2 || job.PublicURLs[0] != "http://localhost:19000/canvas-assets/a.svg" || job.PublicURLs[1] != "http://localhost:19000/canvas-assets/a.render.webp" {
 		t.Fatalf("unexpected cleanup job: %#v", job)
 	}
 	select {

server/internal/application/design_service.go

@@ -5344,7 +5344,10 @@ func mainCanvasPreviewImage(nodes []design.Node) string {
 		if node.Status == "generating" || node.Status == "error" || node.LayerRole == "pen-stroke" {
 			continue
 		}
-		content := strings.TrimSpace(node.Content)
+		content := strings.TrimSpace(node.RenderContent)
+		if content == "" {
+			content = strings.TrimSpace(node.Content)
+		}
 		if content == "" || strings.HasPrefix(content, "data:image/") || !isGeneratedImageContent(content) {
 			continue
 		}

server/internal/application/project_thumbnail.go

@@ -31,6 +31,7 @@ type projectPreviewNode struct {
 	Width          float64 `json:"width"`
 	Height         float64 `json:"height"`
 	Content        string  `json:"content,omitempty"`
+	RenderContent  string  `json:"renderContent,omitempty"`
 	Tone           string  `json:"tone,omitempty"`
 	LayerRole      string  `json:"layerRole,omitempty"`
 	FillColor      string  `json:"fillColor,omitempty"`
@@ -82,6 +83,7 @@ func canvasPreviewNodes(nodes []design.Node) []projectPreviewNode {
 			continue
 		}
 		content := strings.TrimSpace(node.Content)
+		renderContent := strings.TrimSpace(node.RenderContent)
 		if node.Type == design.NodeTypeFrame && !isGeneratedImageContent(content) {
 			content = ""
 		}
@@ -93,6 +95,7 @@ func canvasPreviewNodes(nodes []design.Node) []projectPreviewNode {
 			Width:          math.Max(1, node.Width),
 			Height:         math.Max(1, node.Height),
 			Content:        content,
+			RenderContent:  renderContent,
 			Tone:           strings.TrimSpace(node.Tone),
 			LayerRole:      strings.TrimSpace(node.LayerRole),
 			FillColor:      strings.TrimSpace(node.FillColor),

server/internal/application/project_thumbnail_test.go

@@ -23,13 +23,14 @@ func TestProjectThumbnailUsesCanvasPreview(t *testing.T) {
 				Status:  "success",
 			},
 			{
-				ID:      "main",
+				ID:            "main",
-				Type:    design.NodeTypeImage,
+				Type:          design.NodeTypeImage,
-				Title:   "Main",
+				Title:         "Main",
-				Content: "http://localhost:19000/canvas-assets/main.png",
+				Content:       "http://localhost:19000/canvas-assets/main.svg",
-				Width:   1024,
+				RenderContent: "http://localhost:19000/canvas-assets/main.render.webp",
-				Height:  768,
+				Width:         1024,
-				Status:  "success",
+				Height:        768,
+				Status:        "success",
 			},
 		},
 	}
@@ -49,7 +50,7 @@ func TestProjectThumbnailUsesCanvasPreview(t *testing.T) {
 	if len(preview.Nodes) != 2 {
 		t.Fatalf("expected two preview nodes, got %#v", preview.Nodes)
 	}
-	if preview.Nodes[1].Content != "http://localhost:19000/canvas-assets/main.png" {
+	if preview.Nodes[1].Content != "http://localhost:19000/canvas-assets/main.svg" || preview.Nodes[1].RenderContent != "http://localhost:19000/canvas-assets/main.render.webp" {
 		t.Fatalf("expected generated image in canvas preview, got %#v", preview.Nodes[1])
 	}
 }

server/internal/domain/design/project.go

@@ -130,6 +130,7 @@ type Node struct {
 	Width               float64
 	Height              float64
 	Content             string
+	RenderContent       string
 	Tone                string
 	Status              string
 	ParentID            string

server/internal/infrastructure/postgres/db/models.go

@@ -105,6 +105,7 @@ type CanvasNode struct {
 	FlipY           bool        `json:"flip_y"`
 	Rotation        float64     `json:"rotation"`
 	SemanticContext string      `json:"semantic_context"`
+	RenderContent   string      `json:"render_content"`
 }
 
 type CanvasSnapshot struct {

server/internal/infrastructure/postgres/db/query.sql.go

@@ -467,7 +467,7 @@ func (q *Queries) ListMessagesByProject(ctx context.Context, arg ListMessagesByP
 }
 
 const listNodesByProject = `-- name: ListNodesByProject :many
-SELECT id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context
+SELECT id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context, render_content
 FROM canvas_nodes
 WHERE project_id = $1 AND user_id = $2
 ORDER BY sort_order ASC, id ASC
@@ -521,6 +521,7 @@ func (q *Queries) ListNodesByProject(ctx context.Context, arg ListNodesByProject
 			&i.FlipY,
 			&i.Rotation,
 			&i.SemanticContext,
+			&i.RenderContent,
 		); err != nil {
 			return nil, err
 		}
@@ -746,8 +747,8 @@ func (q *Queries) UpsertBrandKit(ctx context.Context, arg UpsertBrandKitParams)
 }
 
 const upsertCanvasNode = `-- name: UpsertCanvasNode :exec
-INSERT INTO canvas_nodes (id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context)
+INSERT INTO canvas_nodes (id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context, render_content)
-VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21, $22, $23, $24, $25, $26, $27, $28, $29, $30, $31, $32, $33)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21, $22, $23, $24, $25, $26, $27, $28, $29, $30, $31, $32, $33, $34)
 ON CONFLICT (id) DO UPDATE SET
     project_id = EXCLUDED.project_id,
     user_id = EXCLUDED.user_id,
@@ -780,7 +781,8 @@ ON CONFLICT (id) DO UPDATE SET
     flip_x = EXCLUDED.flip_x,
     flip_y = EXCLUDED.flip_y,
     rotation = EXCLUDED.rotation,
-    semantic_context = EXCLUDED.semantic_context
+    semantic_context = EXCLUDED.semantic_context,
+    render_content = EXCLUDED.render_content
 `
 
 type UpsertCanvasNodeParams struct {
@@ -817,6 +819,7 @@ type UpsertCanvasNodeParams struct {
 	FlipY           bool        `json:"flip_y"`
 	Rotation        float64     `json:"rotation"`
 	SemanticContext string      `json:"semantic_context"`
+	RenderContent   string      `json:"render_content"`
 }
 
 func (q *Queries) UpsertCanvasNode(ctx context.Context, arg UpsertCanvasNodeParams) error {
@@ -854,6 +857,7 @@ func (q *Queries) UpsertCanvasNode(ctx context.Context, arg UpsertCanvasNodePara
 		arg.FlipY,
 		arg.Rotation,
 		arg.SemanticContext,
+		arg.RenderContent,
 	)
 	return err
 }

server/internal/infrastructure/postgres/project_repository.go

@@ -199,6 +199,7 @@ func (r *ProjectRepository) Save(ctx context.Context, project design.Project) er
 			Width:           node.Width,
 			Height:          node.Height,
 			Content:         node.Content,
+			RenderContent:   node.RenderContent,
 			Tone:            node.Tone,
 			Status:          node.Status,
 			SortOrder:       int32(index),
@@ -518,6 +519,7 @@ func mapNodes(rows []sqlcdb.CanvasNode) []design.Node {
 			Width:           row.Width,
 			Height:          row.Height,
 			Content:         row.Content,
+			RenderContent:   row.RenderContent,
 			Tone:            row.Tone,
 			Status:          row.Status,
 			ParentID:        row.ParentID,

server/internal/infrastructure/postgres/query.sql

@@ -114,7 +114,7 @@ SET thumbnail = $3,
 WHERE id = $1 AND user_id = $2;
 
 -- name: ListNodesByProject :many
-SELECT id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context
+SELECT id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context, render_content
 FROM canvas_nodes
 WHERE project_id = $1 AND user_id = $2
 ORDER BY sort_order ASC, id ASC;
@@ -124,8 +124,8 @@ DELETE FROM canvas_nodes
 WHERE project_id = $1 AND user_id = $2;
 
 -- name: UpsertCanvasNode :exec
-INSERT INTO canvas_nodes (id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context)
+INSERT INTO canvas_nodes (id, project_id, user_id, node_type, title, x, y, width, height, content, tone, status, sort_order, parent_id, layer_role, font_size, font_family, font_weight, color, text_align, line_height, letter_spacing, text_decoration, text_transform, opacity, fill_color, stroke_color, stroke_width, stroke_style, flip_x, flip_y, rotation, semantic_context, render_content)
-VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21, $22, $23, $24, $25, $26, $27, $28, $29, $30, $31, $32, $33)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21, $22, $23, $24, $25, $26, $27, $28, $29, $30, $31, $32, $33, $34)
 ON CONFLICT (id) DO UPDATE SET
     project_id = EXCLUDED.project_id,
     user_id = EXCLUDED.user_id,
@@ -158,7 +158,8 @@ ON CONFLICT (id) DO UPDATE SET
     flip_x = EXCLUDED.flip_x,
     flip_y = EXCLUDED.flip_y,
     rotation = EXCLUDED.rotation,
-    semantic_context = EXCLUDED.semantic_context;
+    semantic_context = EXCLUDED.semantic_context,
+    render_content = EXCLUDED.render_content;
 
 -- name: ListConnectionsByProject :many
 SELECT id, project_id, user_id, from_node_id, to_node_id

server/internal/infrastructure/postgres/schema.sql

@@ -195,7 +195,8 @@ CREATE TABLE IF NOT EXISTS canvas_nodes (
     flip_x BOOLEAN NOT NULL DEFAULT FALSE,
     flip_y BOOLEAN NOT NULL DEFAULT FALSE,
     rotation DOUBLE PRECISION NOT NULL DEFAULT 0,
-    semantic_context TEXT NOT NULL DEFAULT ''
+    semantic_context TEXT NOT NULL DEFAULT '',
+    render_content TEXT NOT NULL DEFAULT ''
 );
 
 ALTER TABLE canvas_nodes ADD COLUMN IF NOT EXISTS user_id UUID;
@@ -227,6 +228,7 @@ ALTER TABLE canvas_nodes ADD COLUMN IF NOT EXISTS flip_x BOOLEAN NOT NULL DEFAUL
 ALTER TABLE canvas_nodes ADD COLUMN IF NOT EXISTS flip_y BOOLEAN NOT NULL DEFAULT FALSE;
 ALTER TABLE canvas_nodes ADD COLUMN IF NOT EXISTS rotation DOUBLE PRECISION NOT NULL DEFAULT 0;
 ALTER TABLE canvas_nodes ADD COLUMN IF NOT EXISTS semantic_context TEXT NOT NULL DEFAULT '';
+ALTER TABLE canvas_nodes ADD COLUMN IF NOT EXISTS render_content TEXT NOT NULL DEFAULT '';
 
 CREATE INDEX IF NOT EXISTS canvas_nodes_project_id_idx ON canvas_nodes(project_id);
 CREATE INDEX IF NOT EXISTS canvas_nodes_user_project_idx ON canvas_nodes(user_id, project_id);

server/internal/logic/cad_context_mapper_test.go

@@ -13,10 +13,11 @@ func TestCanvasNodeSemanticContextRoundTrip(t *testing.T) {
 		Title:           "plan.svg",
 		LayerRole:       "cad-vector",
 		SemanticContext: "CAD semantic context: layer ROOMS",
+		RenderContent:   "https://assets.example/plan-preview.webp",
 	}}
 
 	roundTrip := toDomainNodes(toAPINodes(nodes))
-	if len(roundTrip) != 1 || roundTrip[0].SemanticContext != nodes[0].SemanticContext {
+	if len(roundTrip) != 1 || roundTrip[0].SemanticContext != nodes[0].SemanticContext || roundTrip[0].RenderContent != nodes[0].RenderContent {
-		t.Fatalf("expected semantic context round trip, got %#v", roundTrip)
+		t.Fatalf("expected CAD context and render content round trip, got %#v", roundTrip)
 	}
 }

server/internal/logic/mapper.go

@@ -259,6 +259,7 @@ func toAPINodes(items []design.Node) []types.CanvasNode {
 			Width:               item.Width,
 			Height:              item.Height,
 			Content:             item.Content,
+			RenderContent:       item.RenderContent,
 			Tone:                item.Tone,
 			Status:              item.Status,
 			ParentId:            item.ParentID,
@@ -302,6 +303,7 @@ func toDomainNodes(items []types.CanvasNode) []design.Node {
 			Width:               item.Width,
 			Height:              item.Height,
 			Content:             item.Content,
+			RenderContent:       item.RenderContent,
 			Tone:                item.Tone,
 			Status:              item.Status,
 			ParentID:            item.ParentId,

server/internal/logic/query_project_logic.go

@@ -109,7 +109,11 @@ func queryProjectCoverList(project design.Project) []string {
 			break
 		}
 		if (node.Type == design.NodeTypeImage || node.Type == design.NodeTypeFrame) && node.Status == "success" {
-			add(node.Content)
+			if strings.TrimSpace(node.RenderContent) != "" {
+				add(node.RenderContent)
+			} else {
+				add(node.Content)
+			}
 		}
 	}
 	return covers

server/internal/types/types.go

@@ -283,6 +283,7 @@ type CanvasNode struct {
 	Width               float64       `json:"width"`
 	Height              float64       `json:"height"`
 	Content             string        `json:"content"`
+	RenderContent       string        `json:"renderContent,optional"`
 	Tone                string        `json:"tone"`
 	Status              string        `json:"status"`
 	ParentId            string        `json:"parentId,optional"`