fix(authz): preserve board org-membership check in assertBoardOrAgent

Greptile flagged that swapping `assertBoardOrgAccess` → `assertBoardOrAgent`
on `GET /api/plugins/tools` and `POST /api/plugins/tools/execute` silently
dropped the org-membership check for board actors. `GET /api/plugins/tools`
has no downstream company-scope guard, so memberless board users could
enumerate every installed plugin tool.

Tighten `assertBoardOrAgent` to delegate the board branch back to
`assertBoardOrgAccess` (require company membership or instance-admin) while
keeping the new agent-JWT path. Adds a regression test asserting a board
user with no memberships gets 403 on tool listing.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/__tests__/plugin-routes-authz.test.ts

@@ -915,6 +915,28 @@ describe.sequential("plugin tool and bridge authz", () => {
 
   // ─── Agent JWT tool execution (cherry-picked from #5549) ─────────────────────
 
+  it("rejects board users with no company memberships from listing plugin tools", async () => {
+    const listToolsForAgent = vi.fn(() => []);
+    const { app } = await createApp(
+      boardActor({ companyIds: [], isInstanceAdmin: false, source: "session" }),
+      {},
+      {
+        toolDeps: {
+          toolDispatcher: {
+            listToolsForAgent,
+            getTool: vi.fn(),
+            executeTool: vi.fn(),
+          },
+        },
+      },
+    );
+
+    const res = await request(app).get("/api/plugins/tools");
+
+    expect(res.status).toBe(403);
+    expect(listToolsForAgent).not.toHaveBeenCalled();
+  });
+
   it("allows agent JWT to list available plugin tools", async () => {
     const listToolsForAgent = vi.fn(() => []);
     const { app } = await createApp(agentActor(), {}, {

server/src/routes/authz.ts

@@ -32,9 +32,14 @@ export function assertBoardOrgAccess(req: Request) {
 }
 
 export function assertBoardOrAgent(req: Request) {
-  if (req.actor.type !== "board" && req.actor.type !== "agent") {
-    throw forbidden("Board or agent access required");
+  if (req.actor.type === "agent") {
+    return;
   }
+  if (req.actor.type === "board") {
+    assertBoardOrgAccess(req);
+    return;
+  }
+  throw forbidden("Board or agent access required");
 }
 
 export function assertInstanceAdmin(req: Request) {