feat(memory): implement stability stage

Co-authored-by: multica-agent <github@multica.ai>

apps/web/server/api/v1/usage.get.ts

@@ -0,0 +1,61 @@
+import { requireStageTwoUser, stageTwoApiError, stageTwoDatabase } from '~/server/utils/stage-two-supabase'
+
+interface UsageRow {
+  campaign_id: string | null
+  request_kind: string
+  input_tokens: number
+  output_tokens: number
+  cost_usd: number | string
+  latency_ms: number | null
+  created_at: string
+}
+
+export default defineEventHandler(async (event) => {
+  try {
+    const user = await requireStageTwoUser(event)
+    const since = new Date()
+    since.setUTCDate(since.getUTCDate() - 30)
+    const today = new Date()
+    today.setUTCHours(0, 0, 0, 0)
+    const [usage, quotaEvents] = await Promise.all([
+      stageTwoDatabase<UsageRow[]>(
+        `ai_usage?select=campaign_id,request_kind,input_tokens,output_tokens,cost_usd,latency_ms,created_at&user_id=eq.${user.id}&created_at=gte.${encodeURIComponent(since.toISOString())}&order=created_at.desc&limit=1000`,
+      ),
+      stageTwoDatabase<Array<{ created_at: string }>>(
+        `ai_quota_events?select=created_at&user_id=eq.${user.id}&created_at=gte.${encodeURIComponent(today.toISOString())}`,
+      ),
+    ])
+    const campaignIds = [...new Set(usage.flatMap(row => row.campaign_id ? [row.campaign_id] : []))]
+    const campaigns = campaignIds.length
+      ? await stageTwoDatabase<Array<{ id: string; title: string }>>(`campaigns?select=id,title&id=in.(${campaignIds.join(',')})`)
+      : []
+    const campaignNames = new Map(campaigns.map(campaign => [campaign.id, campaign.title]))
+    const summarize = (rows: UsageRow[]) => {
+      const latencies = rows.flatMap(row => row.latency_ms === null ? [] : [Number(row.latency_ms)])
+      return {
+        requests: rows.length,
+        inputTokens: rows.reduce((sum, row) => sum + Number(row.input_tokens), 0),
+        outputTokens: rows.reduce((sum, row) => sum + Number(row.output_tokens), 0),
+        costUsd: rows.reduce((sum, row) => sum + Number(row.cost_usd), 0),
+        averageLatencyMs: latencies.length ? Math.round(latencies.reduce((sum, value) => sum + value, 0) / latencies.length) : 0,
+      }
+    }
+    const grouped = new Map<string, UsageRow[]>()
+    for (const row of usage) {
+      const key = row.campaign_id ?? 'coauthor'
+      grouped.set(key, [...(grouped.get(key) ?? []), row])
+    }
+    return {
+      periodDays: 30,
+      quota: { usedToday: quotaEvents.length, dailyRequestLimit: 60, dailyTokenLimit: 250000 },
+      totals: summarize(usage),
+      groups: [...grouped].map(([id, rows]) => ({
+        id,
+        label: id === 'coauthor' ? 'World coauthor' : campaignNames.get(id) ?? 'Private campaign',
+        ...summarize(rows),
+      })).sort((left, right) => right.costUsd - left.costUsd),
+    }
+  } catch (error) {
+    stageTwoApiError(error)
+  }
+})