fix(dashboard): use per-project chatStore in chat session API routes

In multi-project mode, all /chat/sessions* handlers used options.chatStore
(the home-dir project's store) regardless of the projectId query param.
Sessions in secondary projects were invisible via the API.

Root cause: registerChatRoutes accessed options.chatStore directly instead
of routing through resolveProjectChatContext (already used correctly in
registerChatRoomRoutes for the rooms API).

Fix: introduce resolveScopedChatStore(projectId) helper that delegates to
resolveProjectChatContext, replacing all ten options.chatStore usages.
Falls back to default store when engineManager is absent (backward compat).

Tests: add two cases to verify engine-scoped chatStore is used when
engineManager is configured for the requested projectId.

.changeset/fix-chat-sessions-multi-project-scope.md

@@ -0,0 +1,21 @@
+---
+"@runfusion/fusion": patch
+---
+
+Fix chat session API endpoints ignoring `projectId` in multi-project mode.
+
+`GET /chat/sessions`, `GET /chat/sessions/:id`, `GET /chat/sessions/:id/messages`
+and related mutation endpoints all used `options.chatStore` (the home-directory
+project's store) regardless of the `projectId` query parameter. In a multi-project
+daemon (e.g. running from `~/`) sessions belonging to secondary projects were
+invisible — list returned empty, fetching by ID returned 404.
+
+Root cause: `registerChatRoutes` accessed `options.chatStore` directly instead of
+routing through the per-project `resolveProjectChatContext` helper (already used
+correctly by `registerChatRoomRoutes` for the rooms API).
+
+Fix: introduce a `resolveScopedChatStore(projectId)` helper inside
+`registerChatRoutes` that delegates to `resolveProjectChatContext`, and replace
+all ten `options.chatStore` usages with calls to this helper. When `engineManager`
+is present and has an engine for the given `projectId`, the engine's own
+`ChatStore` is used; otherwise falls back to the default store (backward compatible).

packages/dashboard/src/__tests__/chat-routes.test.ts

@@ -505,6 +505,46 @@ describe("Chat API Routes", () => {
       expect(enrichedSession.lastMessagePreview).toBeUndefined();
       expect(enrichedSession.lastMessageAt).toBeUndefined();
     });
+
+    it("uses engine chatStore when engineManager is configured for requested projectId", async () => {
+      const { createServer } = await import("../server.js");
+
+      // Engine-scoped chatStore — simulates a secondary project's DB
+      const engineListSessions = vi.fn().mockReturnValue([sampleSession]);
+      const engineChatStore = {
+        ...mockChatStoreInstance,
+        listSessions: engineListSessions,
+        getLastMessageForSessions: vi.fn().mockReturnValue(new Map()),
+      };
+      const mockEngine = { getChatStore: () => engineChatStore };
+      const mockEngineManager = {
+        getEngine: vi.fn((id: string) => (id === "proj-secondary" ? mockEngine : undefined)),
+        getAllEngines: vi.fn().mockReturnValue(new Map([["proj-secondary", mockEngine]])),
+      };
+
+      const appWithEngine = createServer(store as any, {
+        chatStore: mockChatStore as any,
+        chatManager: mockChatManager as any,
+        engineManager: mockEngineManager as any,
+      });
+
+      const response = await request(appWithEngine, "GET", "/api/chat/sessions?projectId=proj-secondary");
+
+      expect(response.status).toBe(200);
+      // Engine chatStore was used, not the default one
+      expect(engineListSessions).toHaveBeenCalled();
+      expect(mockListSessions).not.toHaveBeenCalled();
+    });
+
+    it("falls back to default chatStore when no engineManager is configured", async () => {
+      mockListSessions.mockReturnValue([sampleSession]);
+
+      // app has no engineManager (the default setup)
+      const response = await request(app, "GET", "/api/chat/sessions?projectId=proj-001");
+
+      expect(response.status).toBe(200);
+      expect(mockListSessions).toHaveBeenCalledWith({ projectId: "proj-001" });
+    });
   });
 
   describe("POST /api/chat/sessions", () => {
@@ -684,6 +724,34 @@ describe("Chat API Routes", () => {
       expect(response.status).toBe(404);
       expect((response.body as any).error).toContain("not found");
     });
+
+    it("uses engine chatStore to find session when projectId is provided", async () => {
+      const { createServer } = await import("../server.js");
+
+      const engineSession = { ...sampleSession, id: "chat-engine-456", projectId: "proj-secondary" };
+      const engineGetSession = vi.fn((id: string) => (id === "chat-engine-456" ? engineSession : undefined));
+      const engineChatStore = { ...mockChatStoreInstance, getSession: engineGetSession };
+      const mockEngine = { getChatStore: () => engineChatStore };
+      const mockEngineManager = {
+        getEngine: vi.fn((id: string) => (id === "proj-secondary" ? mockEngine : undefined)),
+        getAllEngines: vi.fn().mockReturnValue(new Map([["proj-secondary", mockEngine]])),
+      };
+
+      // Default chatStore does NOT have this session
+      mockGetSession.mockReturnValue(undefined);
+
+      const appWithEngine = createServer(store as any, {
+        chatStore: mockChatStore as any,
+        chatManager: mockChatManager as any,
+        engineManager: mockEngineManager as any,
+      });
+
+      const response = await request(appWithEngine, "GET", "/api/chat/sessions/chat-engine-456?projectId=proj-secondary");
+
+      expect(response.status).toBe(200);
+      expect((response.body as any).session.id).toBe("chat-engine-456");
+      expect(engineGetSession).toHaveBeenCalledWith("chat-engine-456");
+    });
   });
 
   describe("PATCH /api/chat/sessions/:id", () => {

packages/dashboard/src/routes/register-chat-routes.ts

@@ -4,6 +4,7 @@ import { mkdir, rm, writeFile } from "node:fs/promises";
 import { basename, join, resolve } from "node:path";
 import type { EnrichedChatSession, ChatAttachment } from "@fusion/core";
 import { ApiError, badRequest, internalError, notFound } from "../api-error.js";
+import { resolveProjectChatContext } from "../chat-project-services.js";
 import { CHAT_ALLOWED_MIME_TYPES, CHAT_MAX_ATTACHMENT_SIZE } from "./chat-attachment-config.js";
 import { rateLimit, RATE_LIMITS } from "../rate-limit.js";
 import { writeSSEEvent, type SessionBufferedEvent } from "../sse-buffer.js";
@@ -27,9 +28,18 @@ function resolveAttachmentPath(rootDir: string, sessionId: string, filename: str
 }
 
 export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps): void {
-  const { router, options, getProjectContext, chatLogger, rethrowAsApiError } = ctx;
+  const { router, options, store, getProjectContext, chatLogger, rethrowAsApiError } = ctx;
   const { parseLastEventId, replayBufferedSSE, validateOptionalModelField, upload } = deps;
 
+  async function resolveScopedChatStore(projectId: string | undefined) {
+    return resolveProjectChatContext({
+      projectId,
+      defaultStore: store,
+      defaultChatStore: options?.chatStore,
+      engineManager: options?.engineManager,
+    });
+  }
+
   const uploadChatAttachment: import("express").RequestHandler = (req, res, next) => {
     upload.single("file")(req, res, (err?: unknown) => {
       if (!err) {
@@ -56,11 +66,6 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.get("/chat/sessions", rateLimit(RATE_LIMITS.api), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
-
       const { projectId, status, agentId, lookup, modelProvider, modelId } = req.query as {
         projectId?: string;
         status?: string;
@@ -69,6 +74,7 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
         modelProvider?: string;
         modelId?: string;
       };
+      const { chatStore } = await resolveScopedChatStore(projectId);
 
       const isResumeLookup = lookup === "resume";
       const hasModelProvider = typeof modelProvider === "string" && modelProvider.trim().length > 0;
@@ -144,13 +150,9 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.post("/chat/sessions", rateLimit(RATE_LIMITS.mutation), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
-
       // Get project context to scope the session and resolve agent from the correct store
       const { store: scopedStore, projectId } = await getProjectContext(req);
+      const { chatStore } = await resolveScopedChatStore(projectId);
       const { AgentStore } = await import("@fusion/core");
       const agentStore = new AgentStore({ rootDir: scopedStore.getFusionDir() });
       await agentStore.init();
@@ -220,10 +222,7 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.get("/chat/sessions/:id", async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
 
       const sessionId = String(req.params.id);
       const session = chatStore.getSession(sessionId);
@@ -250,10 +249,7 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.patch("/chat/sessions/:id", rateLimit(RATE_LIMITS.mutation), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
 
       const sessionId = String(req.params.id);
       const { title, status } = req.body as { title?: string; status?: string };
@@ -287,11 +283,8 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.delete("/chat/sessions/:id", rateLimit(RATE_LIMITS.mutation), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
       const sessionId = String(req.params.id);
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
 
       const deleted = chatStore.deleteSession(sessionId);
       if (!deleted) {
@@ -314,10 +307,7 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.get("/chat/sessions/:id/messages", async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
 
       const sessionId = String(req.params.id);
 
@@ -363,10 +353,7 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
 
   router.post("/chat/sessions/:id/attachments", rateLimit(RATE_LIMITS.mutation), uploadChatAttachment, async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
 
       const sessionId = String(req.params.id);
       const session = chatStore.getSession(sessionId);
@@ -456,10 +443,10 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.get("/chat/sessions/:id/stream", rateLimit(RATE_LIMITS.sse), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
       const chatManager = options?.chatManager;
-      if (!chatStore || !chatManager) {
+      if (!chatManager) {
-        throw internalError("Chat store or manager not available");
+        throw internalError("Chat manager not available");
       }
 
       const sessionId = String(req.params.id);
@@ -545,10 +532,10 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.post("/chat/sessions/:id/messages", rateLimit(RATE_LIMITS.sse), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
       const chatManager = options?.chatManager;
-      if (!chatStore || !chatManager) {
+      if (!chatManager) {
-        throw internalError("Chat store or manager not available");
+        throw internalError("Chat manager not available");
       }
 
       const { content, modelProvider, modelId, attachments } = req.body as {
@@ -711,10 +698,7 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
    */
   router.delete("/chat/sessions/:id/messages/:messageId", rateLimit(RATE_LIMITS.mutation), async (req, res) => {
     try {
-      const chatStore = options?.chatStore;
+      const { chatStore } = await resolveScopedChatStore(req.query.projectId as string | undefined);
-      if (!chatStore) {
-        throw internalError("Chat store not available");
-      }
 
       const sessionId = String(req.params.id);
       const messageId = String(req.params.messageId);