feat(api): add Lovart-style project and agent thread endpoints

Add canva/canda-compatible routes for lightweight project open/save and
agent thread history:
- POST /canva/project/queryProject, saveProject
- POST /canva/agent/queryAgentLastThread, agentThreadList
- GET /canda/chat-history, /canda/thread/status

Canvas save now accepts a compressed SHAKKERDATA:// snapshot payload,
preserves connections, and returns a SaveProject response; blank
successful image nodes are backfilled from generated artifacts. Frontend
designGateway adopts the new save/query flow.

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

server/internal/handler/agent_thread_list_handler.go

@@ -0,0 +1,31 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func agentThreadListHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.AgentThreadListRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+
+		l := logic.NewAgentThreadListLogic(r.Context(), svcCtx)
+		resp, err := l.AgentThreadList(&req)
+		if err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+		} else {
+			httpx.OkJsonCtx(r.Context(), w, resp)
+		}
+	}
+}

server/internal/handler/canda_chat_history_handler.go

@@ -0,0 +1,31 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func candaChatHistoryHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.CandaChatHistoryRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+
+		l := logic.NewCandaChatHistoryLogic(r.Context(), svcCtx)
+		resp, err := l.CandaChatHistory(&req)
+		if err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+		} else {
+			httpx.OkJsonCtx(r.Context(), w, resp)
+		}
+	}
+}

server/internal/handler/canda_thread_status_handler.go

@@ -0,0 +1,31 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func candaThreadStatusHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.CandaThreadStatusRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+
+		l := logic.NewCandaThreadStatusLogic(r.Context(), svcCtx)
+		resp, err := l.CandaThreadStatus(&req)
+		if err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+		} else {
+			httpx.OkJsonCtx(r.Context(), w, resp)
+		}
+	}
+}

server/internal/handler/query_agent_last_thread_handler.go

@@ -0,0 +1,31 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func queryAgentLastThreadHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.QueryAgentLastThreadRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+
+		l := logic.NewQueryAgentLastThreadLogic(r.Context(), svcCtx)
+		resp, err := l.QueryAgentLastThread(&req)
+		if err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+		} else {
+			httpx.OkJsonCtx(r.Context(), w, resp)
+		}
+	}
+}

server/internal/handler/query_project_handler.go

@@ -0,0 +1,31 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func queryProjectHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.QueryProjectRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+
+		l := logic.NewQueryProjectLogic(r.Context(), svcCtx)
+		resp, err := l.QueryProject(&req)
+		if err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+		} else {
+			httpx.OkJsonCtx(r.Context(), w, resp)
+		}
+	}
+}

server/internal/handler/routes.go

@@ -94,6 +94,36 @@ func RegisterHandlers(server *rest.Server, serverCtx *svc.ServiceContext) {
 				Path:    "/auth/options",
 				Handler: getAuthOptionsHandler(serverCtx),
 			},
+			{
+				Method:  http.MethodGet,
+				Path:    "/canda/chat-history",
+				Handler: candaChatHistoryHandler(serverCtx),
+			},
+			{
+				Method:  http.MethodGet,
+				Path:    "/canda/thread/status",
+				Handler: candaThreadStatusHandler(serverCtx),
+			},
+			{
+				Method:  http.MethodPost,
+				Path:    "/canva/agent/agentThreadList",
+				Handler: agentThreadListHandler(serverCtx),
+			},
+			{
+				Method:  http.MethodPost,
+				Path:    "/canva/agent/queryAgentLastThread",
+				Handler: queryAgentLastThreadHandler(serverCtx),
+			},
+			{
+				Method:  http.MethodPost,
+				Path:    "/canva/project/queryProject",
+				Handler: queryProjectHandler(serverCtx),
+			},
+			{
+				Method:  http.MethodPost,
+				Path:    "/canva/project/saveProject",
+				Handler: saveProjectHandler(serverCtx),
+			},
 			{
 				Method:  http.MethodPost,
 				Path:    "/context/vision/recognize_object",

server/internal/handler/save_project_handler.go

@@ -0,0 +1,31 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func saveProjectHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.SaveProjectRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+
+		l := logic.NewSaveProjectLogic(r.Context(), svcCtx)
+		resp, err := l.SaveProject(&req)
+		if err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+		} else {
+			httpx.OkJsonCtx(r.Context(), w, resp)
+		}
+	}
+}