feat(server): add brand kit management and project binding

Add a brand kit domain with memory and postgres stores, a BrandKitService
for CRUD and resolution, and REST endpoints to list, upsert, and delete
brand kits. Projects can bind a brand kit whose resolved context and
reference images feed into the agent's long-term memory and design prompts.

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

server/internal/infrastructure/piagent/brand_kit_context_test.go

@@ -0,0 +1,48 @@
+package piagent
+
+import (
+	"strings"
+	"testing"
+
+	"img_infinite_canvas/internal/domain/design"
+)
+
+func TestBrandKitContextReachesPlannerAndDirectImagePrompts(t *testing.T) {
+	project := design.Project{
+		Title:        "Campaign",
+		Brief:        "Launch visual",
+		BrandKitID:   "brand-kit-alpha",
+		BrandContext: "Primary color: Signal Green #28C76F. Typography: Avenir Next.",
+	}
+	planner := projectBriefContext(project)
+	direct := directImagePrompt(design.AgentRequest{Project: project, Prompt: "Create a product hero"})
+	fallback := fallbackImagePrompt(design.AgentRequest{
+		Project: project,
+		Prompt:  "Create a product hero",
+		TaskPlan: design.AgentTaskPlan{ImageTasks: []design.AgentImageTask{
+			{Title: "Hero", Brief: "Centered product"},
+		}},
+	}, 0)
+	for name, value := range map[string]string{"planner": planner, "direct": direct, "fallback": fallback} {
+		if !strings.Contains(value, "Signal Green #28C76F") || !strings.Contains(value, "Avenir Next") {
+			t.Fatalf("%s prompt omitted Brand Kit context: %s", name, value)
+		}
+	}
+}
+
+func TestBrandKitImagesFollowUserReferences(t *testing.T) {
+	req := design.AgentRequest{
+		Project: design.Project{BrandImages: []string{
+			"data:image/png;base64,YnJhbmQtbG9nbw==",
+			"data:image/webp;base64,YnJhbmQtcmVmZXJlbmNl",
+		}},
+		Messages: []design.AgentChatMessage{{Contents: []design.AgentContent{{Type: "image", ImageURL: "https://example.com/user-reference.png"}}}},
+	}
+	images := referenceImageURLs(req)
+	if len(images) != 3 {
+		t.Fatalf("expected user and Brand Kit references, got %#v", images)
+	}
+	if images[0] != "https://example.com/user-reference.png" || images[1] != req.Project.BrandImages[0] || images[2] != req.Project.BrandImages[1] {
+		t.Fatalf("expected user references before Brand Kit images, got %#v", images)
+	}
+}

server/internal/infrastructure/piagent/creative_agent.go

@@ -843,6 +843,11 @@ func projectBriefContext(project design.Project) string {
 		builder.WriteString(project.Brief)
 		builder.WriteString("\n")
 	}
+	if strings.TrimSpace(project.BrandContext) != "" {
+		builder.WriteString("Brand Kit context:\n")
+		builder.WriteString(strings.TrimSpace(project.BrandContext))
+		builder.WriteString("\n")
+	}
 	builder.WriteString(fmt.Sprintf("Canvas nodes: %d", len(project.Nodes)))
 	return builder.String()
 }

server/internal/infrastructure/piagent/design_agent.go

@@ -210,7 +210,7 @@ func directImagePlan(req design.AgentRequest) design.AgentPlan {
 
 func directImagePrompts(req design.AgentRequest) []design.AgentImagePrompt {
 	count := plannedGenerationCount(req)
-	prompt := strings.TrimSpace(req.Prompt)
+	prompt := directImagePrompt(req)
 	if prompt == "" {
 		prompt = fallbackDirectImagePrompt(req)
 	}
@@ -257,7 +257,7 @@ func directImageTasksSharePrompt(req design.AgentRequest) bool {
 }
 
 func directImageBatchPrompt(req design.AgentRequest) design.AgentImagePrompt {
-	prompt := strings.TrimSpace(req.Prompt)
+	prompt := directImagePrompt(req)
 	if prompt == "" {
 		prompt = fallbackDirectImagePrompt(req)
 	}
@@ -614,6 +614,12 @@ func referenceImageURLs(req design.AgentRequest) []string {
 			}
 		}
 	}
+	for _, image := range req.Project.BrandImages {
+		add(image)
+		if len(urls) >= 16 {
+			return urls[:16]
+		}
+	}
 	if len(urls) > 16 {
 		return urls[:16]
 	}
@@ -662,9 +668,9 @@ func fallbackImagePrompt(req design.AgentRequest, index int) string {
 		task := req.TaskPlan.ImageTasks[index]
 		if brief := strings.TrimSpace(task.Brief); brief != "" {
 			if title := strings.TrimSpace(task.Title); title != "" && !strings.Contains(brief, title) {
-				return title + ": " + brief
+				return imagePromptWithBrandKit(title+": "+brief, req)
 			}
-			return brief
+			return imagePromptWithBrandKit(brief, req)
 		}
 	}
 	return fallbackDirectImagePrompt(req)
@@ -1064,6 +1070,9 @@ func fallbackDirectImagePrompt(req design.AgentRequest) string {
 	if brief := strings.TrimSpace(req.Project.Brief); brief != "" {
 		lines = append(lines, "Project brief: "+truncateRunes(brief, 180))
 	}
+	if brandContext := strings.TrimSpace(req.Project.BrandContext); brandContext != "" {
+		lines = append(lines, "Binding Brand Kit: "+truncateRunes(brandContext, 520))
+	}
 	if memory := compactFallbackMemory(req.Memory); memory != "" {
 		lines = append(lines, "Relevant memory: "+memory)
 	}
@@ -1080,6 +1089,19 @@ func fallbackDirectImagePrompt(req design.AgentRequest) string {
 	return compactImageGenerationPrompt(strings.Join(lines, "\n"), imageGenerationFallbackMaxRunes)
 }
 
+func directImagePrompt(req design.AgentRequest) string {
+	return imagePromptWithBrandKit(req.Prompt, req)
+}
+
+func imagePromptWithBrandKit(prompt string, req design.AgentRequest) string {
+	prompt = strings.TrimSpace(prompt)
+	brandContext := strings.TrimSpace(req.Project.BrandContext)
+	if brandContext == "" {
+		return prompt
+	}
+	return strings.TrimSpace(prompt + "\n\nBinding Brand Kit requirements:\n" + brandContext)
+}
+
 func compactFallbackMemory(memory design.AgentMemory) string {
 	if memory.IsZero() {
 		return ""