diff --git a/packages/llm/src/schema/events.ts b/packages/llm/src/schema/events.ts
index b2109f3693..212a01f6a3 100644
--- a/packages/llm/src/schema/events.ts
+++ b/packages/llm/src/schema/events.ts
@@ -256,9 +256,15 @@ export const LLMEvent = Object.assign(llmEventTagged, {
   toolResult: (input: WithID<ToolResult, ToolCallID>) => ToolResult.make({ ...input, id: toolCallID(input.id) }),
   toolError: (input: WithID<ToolError, ToolCallID>) => ToolError.make({ ...input, id: toolCallID(input.id) }),
   stepFinish: (input: WithUsage<StepFinish>) =>
-    StepFinish.make({ ...input, usage: input.usage instanceof Usage ? input.usage : new Usage(input.usage ?? {}) }),
+    StepFinish.make({
+      ...input,
+      usage: input.usage === undefined ? undefined : input.usage instanceof Usage ? input.usage : new Usage(input.usage),
+    }),
   requestFinish: (input: WithUsage<RequestFinish>) =>
-    RequestFinish.make({ ...input, usage: input.usage instanceof Usage ? input.usage : new Usage(input.usage ?? {}) }),
+    RequestFinish.make({
+      ...input,
+      usage: input.usage === undefined ? undefined : input.usage instanceof Usage ? input.usage : new Usage(input.usage),
+    }),
   providerError: ProviderErrorEvent.make,
   is: {
     requestStart: llmEventTagged.guards["request-start"],
diff --git a/packages/opencode/src/session/llm-ai-sdk.ts b/packages/opencode/src/session/llm-ai-sdk.ts
index 9d5407f975..bba31861e1 100644
--- a/packages/opencode/src/session/llm-ai-sdk.ts
+++ b/packages/opencode/src/session/llm-ai-sdk.ts
@@ -1,4 +1,4 @@
-import { ContentBlockID, FinishReason, LLMEvent, ProviderMetadata, ToolCallID, ToolResultValue, Usage } from "@opencode-ai/llm"
+import { FinishReason, LLMEvent, ProviderMetadata, ToolResultValue } from "@opencode-ai/llm"
 import { Effect, Schema } from "effect"
 import { type streamText } from "ai"
 import { errorMessage } from "@/util/error"
@@ -11,15 +11,12 @@ export function adapterState() {
     step: 0,
     text: 0,
     reasoning: 0,
-    currentTextID: undefined as ContentBlockID | undefined,
-    currentReasoningID: undefined as ContentBlockID | undefined,
+    currentTextID: undefined as string | undefined,
+    currentReasoningID: undefined as string | undefined,
     toolNames: {} as Record<string, string>,
   }
 }
 
-const contentBlockID = (value: string) => ContentBlockID.make(value)
-const toolCallID = (value: string) => ToolCallID.make(value)
-
 function finishReason(value: string | undefined): FinishReason {
   return Schema.is(FinishReason)(value) ? value : "unknown"
 }
@@ -28,7 +25,7 @@ function providerMetadata(value: unknown): ProviderMetadata | undefined {
   return Schema.is(ProviderMetadata)(value) ? value : undefined
 }
 
-function usage(value: unknown): Usage | undefined {
+function usage(value: unknown) {
   if (!value || typeof value !== "object") return undefined
   const item = value as {
     inputTokens?: number
@@ -49,7 +46,17 @@ function usage(value: unknown): Usage | undefined {
       cacheWriteInputTokens: item.inputTokenDetails?.cacheWriteTokens,
     }).filter((entry) => entry[1] !== undefined),
   )
-  return new Usage(result)
+  return result
+}
+
+function currentTextID(state: ReturnType<typeof adapterState>, id: string | undefined) {
+  state.currentTextID = id ?? state.currentTextID ?? `text-${state.text++}`
+  return state.currentTextID
+}
+
+function currentReasoningID(state: ReturnType<typeof adapterState>, id: string | undefined) {
+  state.currentReasoningID = id ?? state.currentReasoningID ?? `reasoning-${state.reasoning++}`
+  return state.currentReasoningID
 }
 
 export function toLLMEvents(
@@ -86,7 +93,7 @@ export function toLLMEvents(
 
     case "text-start":
       return Effect.sync(() => {
-        state.currentTextID = contentBlockID(event.id ?? `text-${state.text++}`)
+        state.currentTextID = currentTextID(state, event.id)
         return [
           LLMEvent.textStart({
             id: state.currentTextID,
@@ -98,7 +105,7 @@ export function toLLMEvents(
     case "text-delta":
       return Effect.succeed([
         LLMEvent.textDelta({
-          id: event.id ? contentBlockID(event.id) : (state.currentTextID ?? contentBlockID(`text-${state.text++}`)),
+          id: currentTextID(state, event.id),
           text: event.text,
         }),
       ])
@@ -106,14 +113,14 @@ export function toLLMEvents(
     case "text-end":
       return Effect.succeed([
         LLMEvent.textEnd({
-          id: event.id ? contentBlockID(event.id) : (state.currentTextID ?? contentBlockID(`text-${state.text++}`)),
+          id: currentTextID(state, event.id),
           providerMetadata: providerMetadata(event.providerMetadata),
         }),
       ])
 
     case "reasoning-start":
       return Effect.sync(() => {
-        state.currentReasoningID = contentBlockID(event.id)
+        state.currentReasoningID = currentReasoningID(state, event.id)
         return [
           LLMEvent.reasoningStart({
             id: state.currentReasoningID,
@@ -125,14 +132,14 @@ export function toLLMEvents(
     case "reasoning-delta":
       return Effect.succeed([
         LLMEvent.reasoningDelta({
-          id: event.id ? contentBlockID(event.id) : (state.currentReasoningID ?? contentBlockID(`reasoning-${state.reasoning++}`)),
+          id: currentReasoningID(state, event.id),
           text: event.text,
         }),
       ])
 
     case "reasoning-end":
       return Effect.sync(() => {
-        const id = contentBlockID(event.id)
+        const id = currentReasoningID(state, event.id)
         state.currentReasoningID = undefined
         return [
           LLMEvent.reasoningEnd({
@@ -147,7 +154,7 @@ export function toLLMEvents(
         state.toolNames[event.id] = event.toolName
         return [
           LLMEvent.toolInputStart({
-            id: toolCallID(event.id),
+            id: event.id,
             name: event.toolName,
             providerMetadata: providerMetadata(event.providerMetadata),
           }),
@@ -157,7 +164,7 @@ export function toLLMEvents(
     case "tool-input-delta":
       return Effect.succeed([
         LLMEvent.toolInputDelta({
-          id: toolCallID(event.id),
+          id: event.id,
           name: state.toolNames[event.id] ?? "unknown",
           text: event.delta ?? "",
         }),
@@ -166,7 +173,7 @@ export function toLLMEvents(
     case "tool-input-end":
       return Effect.succeed([
         LLMEvent.toolInputEnd({
-          id: toolCallID(event.id),
+          id: event.id,
           name: state.toolNames[event.id] ?? "unknown",
         }),
       ])
@@ -176,7 +183,7 @@ export function toLLMEvents(
         state.toolNames[event.toolCallId] = event.toolName
         return [
           LLMEvent.toolCall({
-            id: toolCallID(event.toolCallId),
+            id: event.toolCallId,
             name: event.toolName,
             input: event.input,
             providerExecuted: "providerExecuted" in event ? event.providerExecuted : undefined,
@@ -191,7 +198,7 @@ export function toLLMEvents(
         delete state.toolNames[event.toolCallId]
         return [
           LLMEvent.toolResult({
-            id: toolCallID(event.toolCallId),
+            id: event.toolCallId,
             name,
             result: ToolResultValue.make(event.output),
             providerExecuted: "providerExecuted" in event ? event.providerExecuted : undefined,
@@ -205,7 +212,7 @@ export function toLLMEvents(
         delete state.toolNames[event.toolCallId]
         return [
           LLMEvent.toolError({
-            id: toolCallID(event.toolCallId),
+            id: event.toolCallId,
             name,
             message: errorMessage(event.error),
           }),