Add cumulative billing-cycle usage chart

package.json

@@ -35,7 +35,7 @@
     "serve": "npm run build && npm start",
     "preview": "vite preview",
     "lint": "oxlint",
-    "test": "node --test server/lib/range.test.ts server/lib/localhost-intent.test.ts server/lib/localhost.test.ts server/lib/cursor-stamp.test.ts src/lib/types.test.ts src/lib/api.test.ts",
+    "test": "node --test server/lib/range.test.ts server/lib/localhost-intent.test.ts server/lib/localhost.test.ts server/lib/cursor-stamp.test.ts src/lib/types.test.ts src/lib/api.test.ts src/lib/cumulativeUsage.test.ts",
     "setup": "npm run build && npm run launchagent:install",
     "launchagent:install": "bash scripts/install-launchagent.sh",
     "launchagent:uninstall": "bash scripts/uninstall-launchagent.sh"

server/index.ts

@@ -100,11 +100,13 @@ async function buildPayload(
 ): Promise<DashboardPayload> {
   const range = parseRange(typeof rangeRaw === 'string' ? rangeRaw : undefined)
   const { data, cached } = await collectRaw(force)
+  // Dashboard "this billing cycle" follows Cursor's plan cycle when known,
+  // so Claude's rolling weekly window does not pull the shared range back.
+  const sharedCycleStart = data.cursor.usageReset?.cycleStart ?? null
   const agents = withShares(
     [data.cursor, data.claude, data.codex].map((a) => {
-      const cycleStart = a.usageReset?.cycleStart
-      const since = rangeStartDate(range, new Date(), cycleStart)
-      const days = daysInRange(range, new Date(), cycleStart)
+      const since = rangeStartDate(range, new Date(), sharedCycleStart)
+      const days = daysInRange(range, new Date(), sharedCycleStart)
       return applyRange(a, range, since, days)
     }),
   )