fix(session): fix token usage double-counting w/ anthropic & bedrock due to AI SDK v6 upgrade (#19758)

Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>
Co-authored-by: Aiden Cline <aidenpcline@gmail.com>

packages/opencode/src/session/index.ts

@@ -32,7 +32,6 @@ import { ModelID, ProviderID } from "@/provider/schema"
 import { Permission } from "@/permission"
 import { Global } from "@/global"
 import type { LanguageModelV2Usage } from "@ai-sdk/provider"
-import { iife } from "@/util/iife"
 import { Effect, Layer, Scope, ServiceMap } from "effect"
 import { makeRuntime } from "@/effect/run-service"
 
@@ -265,27 +264,12 @@ export namespace Session {
         0) as number,
     )
 
-    // OpenRouter provides inputTokens as the total count of input tokens (including cached).
+    // AI SDK v6 normalized inputTokens to include cached tokens across all providers
-    // AFAIK other providers (OpenRouter/OpenAI/Gemini etc.) do it the same way e.g. vercel/ai#8794 (comment)
+    // (including Anthropic/Bedrock which previously excluded them). Always subtract cache
-    // Anthropic does it differently though - inputTokens doesn't include cached tokens.
+    // tokens to get the non-cached input count for separate cost calculation.
-    // It looks like OpenCode's cost calculation assumes all providers return inputTokens the same way Anthropic does (I'm guessing getUsage logic was originally implemented with anthropic), so it's causing incorrect cost calculation for OpenRouter and others.
+    const adjustedInputTokens = safe(inputTokens - cacheReadInputTokens - cacheWriteInputTokens)
-    const excludesCachedTokens = !!(input.metadata?.["anthropic"] || input.metadata?.["bedrock"])
-    const adjustedInputTokens = safe(
-      excludesCachedTokens ? inputTokens : inputTokens - cacheReadInputTokens - cacheWriteInputTokens,
-    )
 
-    const total = iife(() => {
+    const total = input.usage.totalTokens
-      // Anthropic doesn't provide total_tokens, also ai sdk will vastly undercount if we
-      // don't compute from components
-      if (
-        input.model.api.npm === "@ai-sdk/anthropic" ||
-        input.model.api.npm === "@ai-sdk/amazon-bedrock" ||
-        input.model.api.npm === "@ai-sdk/google-vertex/anthropic"
-      ) {
-        return adjustedInputTokens + outputTokens + cacheReadInputTokens + cacheWriteInputTokens
-      }
-      return input.usage.totalTokens
-    })
 
     const tokens = {
       total,

packages/opencode/test/session/compaction.test.ts

@@ -964,8 +964,9 @@ describe("session.getUsage", () => {
     expect(result.tokens.cache.write).toBe(300)
   })
 
-  test("does not subtract cached tokens for anthropic provider", () => {
+  test("subtracts cached tokens for anthropic provider", () => {
     const model = createModel({ context: 100_000, output: 32_000 })
+    // AI SDK v6 normalizes inputTokens to include cached tokens for all providers
     const result = Session.getUsage({
       model,
       usage: {
@@ -979,7 +980,7 @@ describe("session.getUsage", () => {
       },
     })
 
-    expect(result.tokens.input).toBe(1000)
+    expect(result.tokens.input).toBe(800)
     expect(result.tokens.cache.read).toBe(200)
   })
 
@@ -1043,11 +1044,10 @@ describe("session.getUsage", () => {
     "computes total from components for %s models",
     (npm) => {
       const model = createModel({ context: 100_000, output: 32_000, npm })
+      // AI SDK v6: inputTokens includes cached tokens for all providers
       const usage = {
         inputTokens: 1000,
         outputTokens: 500,
-        // These providers typically report total as input + output only,
-        // excluding cache read/write.
         totalTokens: 1500,
         cachedInputTokens: 200,
       }
@@ -1064,10 +1064,12 @@ describe("session.getUsage", () => {
           },
         })
 
-        expect(result.tokens.input).toBe(1000)
+        // inputTokens (1000) includes cache, so adjusted = 1000 - 200 - 300 = 500
+        expect(result.tokens.input).toBe(500)
         expect(result.tokens.cache.read).toBe(200)
         expect(result.tokens.cache.write).toBe(300)
-        expect(result.tokens.total).toBe(2000)
+        // total = adjusted (500) + output (500) + cacheRead (200) + cacheWrite (300)
+        expect(result.tokens.total).toBe(1500)
         return
       }
 
@@ -1081,10 +1083,12 @@ describe("session.getUsage", () => {
         },
       })
 
-      expect(result.tokens.input).toBe(1000)
+      // inputTokens (1000) includes cache, so adjusted = 1000 - 200 - 300 = 500
+      expect(result.tokens.input).toBe(500)
       expect(result.tokens.cache.read).toBe(200)
       expect(result.tokens.cache.write).toBe(300)
-      expect(result.tokens.total).toBe(2000)
+      // total = adjusted (500) + output (500) + cacheRead (200) + cacheWrite (300)
+      expect(result.tokens.total).toBe(1500)
     },
   )
 })