chore: refactoring and tests (#12468)

packages/app/src/components/session/session-context-metrics.ts

@@ -0,0 +1,94 @@
+import type { AssistantMessage, Message } from "@opencode-ai/sdk/v2/client"
+
+type Provider = {
+  id: string
+  name?: string
+  models: Record<string, Model | undefined>
+}
+
+type Model = {
+  name?: string
+  limit: {
+    context: number
+  }
+}
+
+type Context = {
+  message: AssistantMessage
+  provider?: Provider
+  model?: Model
+  providerLabel: string
+  modelLabel: string
+  limit: number | undefined
+  input: number
+  output: number
+  reasoning: number
+  cacheRead: number
+  cacheWrite: number
+  total: number
+  usage: number | null
+}
+
+type Metrics = {
+  totalCost: number
+  context: Context | undefined
+}
+
+const cache = new WeakMap<Message[], WeakMap<Provider[], Metrics>>()
+
+const tokenTotal = (msg: AssistantMessage) => {
+  return msg.tokens.input + msg.tokens.output + msg.tokens.reasoning + msg.tokens.cache.read + msg.tokens.cache.write
+}
+
+const lastAssistantWithTokens = (messages: Message[]) => {
+  for (let i = messages.length - 1; i >= 0; i--) {
+    const msg = messages[i]
+    if (msg.role !== "assistant") continue
+    if (tokenTotal(msg) <= 0) continue
+    return msg
+  }
+}
+
+const build = (messages: Message[], providers: Provider[]): Metrics => {
+  const totalCost = messages.reduce((sum, msg) => sum + (msg.role === "assistant" ? msg.cost : 0), 0)
+  const message = lastAssistantWithTokens(messages)
+  if (!message) return { totalCost, context: undefined }
+
+  const provider = providers.find((item) => item.id === message.providerID)
+  const model = provider?.models[message.modelID]
+  const limit = model?.limit.context
+  const total = tokenTotal(message)
+
+  return {
+    totalCost,
+    context: {
+      message,
+      provider,
+      model,
+      providerLabel: provider?.name ?? message.providerID,
+      modelLabel: model?.name ?? message.modelID,
+      limit,
+      input: message.tokens.input,
+      output: message.tokens.output,
+      reasoning: message.tokens.reasoning,
+      cacheRead: message.tokens.cache.read,
+      cacheWrite: message.tokens.cache.write,
+      total,
+      usage: limit ? Math.round((total / limit) * 100) : null,
+    },
+  }
+}
+
+export function getSessionContextMetrics(messages: Message[], providers: Provider[]) {
+  const byProvider = cache.get(messages)
+  if (byProvider) {
+    const hit = byProvider.get(providers)
+    if (hit) return hit
+  }
+
+  const value = build(messages, providers)
+  const next = byProvider ?? new WeakMap<Provider[], Metrics>()
+  next.set(providers, value)
+  if (!byProvider) cache.set(messages, next)
+  return value
+}