refactor(mcp): extract all MCP tools into dedicated modules and add shared helpers

server/src/mcp/tools/_shared.ts

@@ -0,0 +1,51 @@
+import { broadcast } from '../../websocket';
+
+export function safeBroadcast(tripId: number, event: string, payload: Record<string, unknown>): void {
+  try {
+    broadcast(tripId, event, payload);
+  } catch (err) {
+    console.error(`[MCP] broadcast failed for ${event}:`, err?.message ?? err);
+  }
+}
+
+export const MAX_MCP_TRIP_DAYS = 90;
+
+export const TOOL_ANNOTATIONS_READONLY = {
+  readOnlyHint: true,
+  destructiveHint: false,
+  idempotentHint: true,
+  openWorldHint: false,
+} as const;
+
+export const TOOL_ANNOTATIONS_WRITE = {
+  readOnlyHint: false,
+  destructiveHint: false,
+  idempotentHint: true,
+  openWorldHint: false,
+} as const;
+
+export const TOOL_ANNOTATIONS_DELETE = {
+  readOnlyHint: false,
+  destructiveHint: true,
+  idempotentHint: true,
+  openWorldHint: false,
+} as const;
+
+export const TOOL_ANNOTATIONS_NON_IDEMPOTENT = {
+  readOnlyHint: false,
+  destructiveHint: false,
+  idempotentHint: false,
+  openWorldHint: false,
+} as const;
+
+export function demoDenied() {
+  return { content: [{ type: 'text' as const, text: 'Write operations are disabled in demo mode.' }], isError: true };
+}
+
+export function noAccess() {
+  return { content: [{ type: 'text' as const, text: 'Trip not found or access denied.' }], isError: true };
+}
+
+export function ok(data: unknown) {
+  return { content: [{ type: 'text' as const, text: JSON.stringify(data, null, 2) }] };
+}