feat(usage): record /v1/messages usage (Task #10)

The /v1/messages route translates Anthropic→OpenAI before sending, so we use the OpenAI accumulator to capture usage. endpoint='messages', upstreamFormat='anthropic' tags the API surface.

Stream branch: feed every chunk into accumulator, finalize on close (ok/aborted/error). Non-stream: normalize response.usage. Errors before the upstream call write a status='error' row.

Refs #10

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

Author: lubobill1990

src/routes/messages/handler.ts

@@ -3,9 +3,18 @@ import type { Context } from "hono"
 import consola from "consola"
 import { streamSSE } from "hono/streaming"
 
+import type { Account } from "~/lib/account-pool"
+
 import { awaitApproval } from "~/lib/approval"
 import { checkRateLimit } from "~/lib/rate-limit"
 import { state } from "~/lib/state"
+import {
+  createOpenAIAccumulator,
+  normalizeOpenAIFinal,
+  UsageMissingError,
+  type NormalizedUsage,
+} from "~/lib/usage-normalizer"
+import { recordUsage } from "~/lib/usage-recorder"
 import { makeApiContext, resolveAndMapModelId } from "~/lib/utils"
 import { withAccount } from "~/lib/with-account"
 import {
@@ -24,6 +33,129 @@ import {
 } from "./non-stream-translation"
 import { translateChunkToAnthropicEvents } from "./stream-translation"
 
+const ZERO_USAGE: NormalizedUsage = {
+  inputTokens: 0,
+  cachedInputTokens: 0,
+  outputTokens: 0,
+  reasoningTokens: 0,
+  totalTokens: 0,
+}
+
+interface RecordCtx {
+  account: Account
+  modelId: string
+  isInternal: boolean
+  tStart: number
+}
+
+interface RecordOkArgs {
+  ctx: RecordCtx
+  usage: NormalizedUsage
+  isStreaming: boolean
+  requestId?: string
+}
+
+interface RecordFailureArgs {
+  ctx: RecordCtx
+  status: "error" | "aborted"
+  isStreaming: boolean
+  usage?: NormalizedUsage
+}
+
+function recordOk(args: RecordOkArgs) {
+  recordUsage({
+    account: args.ctx.account,
+    modelId: args.ctx.modelId,
+    endpoint: "messages",
+    upstreamFormat: "anthropic",
+    isStreaming: args.isStreaming,
+    usage: args.usage,
+    durationMs: Date.now() - args.ctx.tStart,
+    status: "ok",
+    requestId: args.requestId,
+    isInternal: args.ctx.isInternal,
+  })
+}
+
+function recordFailure(args: RecordFailureArgs) {
+  recordUsage({
+    account: args.ctx.account,
+    modelId: args.ctx.modelId,
+    endpoint: "messages",
+    upstreamFormat: "anthropic",
+    isStreaming: args.isStreaming,
+    usage: args.usage ?? ZERO_USAGE,
+    durationMs: Date.now() - args.ctx.tStart,
+    status: args.status,
+    isInternal: args.ctx.isInternal,
+  })
+}
+
+function streamAndRecord(
+  c: Context,
+  response: AsyncIterable<{ data?: string }>,
+  ctx: RecordCtx,
+) {
+  return streamSSE(c, async (stream) => {
+    const accumulator = createOpenAIAccumulator()
+    const streamState: AnthropicStreamState = {
+      messageStartSent: false,
+      contentBlockIndex: 0,
+      contentBlockOpen: false,
+      toolCalls: {},
+    }
+    let status: "ok" | "error" | "aborted" = "ok"
+    let lastRequestId: string | undefined
+
+    try {
+      for await (const rawEvent of response) {
+        if (c.req.raw.signal.aborted) {
+          status = "aborted"
+          break
+        }
+        if (rawEvent.data === "[DONE]") break
+        if (!rawEvent.data) continue
+
+        const chunk = JSON.parse(rawEvent.data) as ChatCompletionChunk
+        if (chunk.id) lastRequestId = chunk.id
+        accumulator.feed(chunk)
+
+        const events = translateChunkToAnthropicEvents(chunk, streamState)
+        for (const event of events) {
+          await stream.writeSSE({
+            event: event.type,
+            data: JSON.stringify(event),
+          })
+        }
+      }
+    } catch (err) {
+      status = "error"
+      consola.error("Streaming /v1/messages error:", err)
+    }
+
+    let usage: NormalizedUsage
+    try {
+      usage = accumulator.finalize()
+    } catch (err) {
+      if (err instanceof UsageMissingError) {
+        consola.warn(
+          "Anthropic stream completed without an include_usage frame; recording zero usage",
+        )
+      } else {
+        consola.error("Failed to finalize Anthropic stream usage:", err)
+      }
+      usage = ZERO_USAGE
+      if (status === "ok") status = "error"
+    }
+
+    if (status === "ok") {
+      recordOk({ ctx, usage, isStreaming: true, requestId: lastRequestId })
+    } else {
+      recordFailure({ ctx, status, isStreaming: true, usage })
+    }
+  })
+}
+
 export async function handleCompletion(c: Context) {
   await checkRateLimit(state)
 
@@ -48,53 +180,84 @@ export async function handleCompletion(c: Context) {
     await awaitApproval()
   }
 
-  const response = await withAccount(c, (account) =>
-    createChatCompletions(makeApiContext(account), openAIPayload),
-  )
+  const isInternal = c.req.header("x-internal-pricing-sync") === "1"
+  const tStart = Date.now()
+  let usedAccount: Account | undefined
+
+  let response: Awaited<ReturnType<typeof createChatCompletions>>
+  try {
+    response = await withAccount(c, (account) => {
+      usedAccount = account
+      return createChatCompletions(makeApiContext(account), openAIPayload)
+    })
+  } catch (err) {
+    if (usedAccount) {
+      recordFailure({
+        ctx: {
+          account: usedAccount,
+          modelId: openAIPayload.model,
+          isInternal,
+          tStart,
+        },
+        status: "error",
+        isStreaming: Boolean(openAIPayload.stream),
+      })
+    }
+    throw err
+  }
 
   if (isNonStreaming(response)) {
     consola.debug(
       "Non-streaming response from Copilot:",
       JSON.stringify(response).slice(-400),
     )
     const anthropicResponse = translateToAnthropic(response)
-    consola.debug(
-      "Translated Anthropic response:",
-      JSON.stringify(anthropicResponse),
-    )
+    if (usedAccount) {
+      recordOk({
+        ctx: {
+          account: usedAccount,
+          modelId: openAIPayload.model,
+          isInternal,
+          tStart,
+        },
+        usage: normalizeOpenAIFinal(response.usage),
+        isStreaming: false,
+        requestId: response.id,
+      })
+    }
     return c.json(anthropicResponse)
   }
 
   consola.debug("Streaming response from Copilot")
-  return streamSSE(c, async (stream) => {
-    const streamState: AnthropicStreamState = {
-      messageStartSent: false,
-      contentBlockIndex: 0,
-      contentBlockOpen: false,
-      toolCalls: {},
-    }
-
-    for await (const rawEvent of response) {
-      consola.debug("Copilot raw stream event:", JSON.stringify(rawEvent))
-      if (rawEvent.data === "[DONE]") {
-        break
+  if (!usedAccount) {
+    return streamSSE(c, async (stream) => {
+      const streamState: AnthropicStreamState = {
+        messageStartSent: false,
+        contentBlockIndex: 0,
+        contentBlockOpen: false,
+        toolCalls: {},
       }
-
-      if (!rawEvent.data) {
-        continue
+      for await (const rawEvent of response) {
+        if (rawEvent.data === "[DONE]") break
+        if (!rawEvent.data) continue
+        const chunk = JSON.parse(rawEvent.data) as ChatCompletionChunk
+        for (const event of translateChunkToAnthropicEvents(
+          chunk,
+          streamState,
+        )) {
+          await stream.writeSSE({
+            event: event.type,
+            data: JSON.stringify(event),
+          })
+        }
       }
-
-      const chunk = JSON.parse(rawEvent.data) as ChatCompletionChunk
-      const events = translateChunkToAnthropicEvents(chunk, streamState)
-
-      for (const event of events) {
-        consola.debug("Translated Anthropic event:", JSON.stringify(event))
-        await stream.writeSSE({
-          event: event.type,
-          data: JSON.stringify(event),
-        })
-      }
-    }
+    })
+  }
+  return streamAndRecord(c, response, {
+    account: usedAccount,
+    modelId: openAIPayload.model,
+    isInternal,
+    tStart,
   })
 }