From 0d4f8d126f3cb2dedde4f7d904243b0ba42ce42a Mon Sep 17 00:00:00 2001
From: Kit Langton <kit.langton@gmail.com>
Date: Sun, 10 May 2026 19:15:46 -0400
Subject: [PATCH] refactor(llm): drop Usage.totalInput / totalOutput helpers
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The additive contract delivers value at the mapper boundary — every
field is non-overlapping and non-negative, so any caller summing
arbitrary subsets is correct by construction. Two-line helpers that
just sum three or two known fields add API surface without paying for
themselves, and there are no in-tree consumers today. If v2 wants them
at integration time, the right place is a getter on the `Schema.Class`
(matching the `LLMResponse.text` / `reasoning` / `toolCalls` pattern in
the same file), not a static namespace helper.
---
 packages/llm/src/schema/events.ts |  9 ---------
 packages/llm/test/schema.test.ts  | 18 +++---------------
 2 files changed, 3 insertions(+), 24 deletions(-)

diff --git a/packages/llm/src/schema/events.ts b/packages/llm/src/schema/events.ts
index e8a2a18892..187291e685 100644
--- a/packages/llm/src/schema/events.ts
+++ b/packages/llm/src/schema/events.ts
@@ -45,15 +45,6 @@ export class Usage extends Schema.Class<Usage>("LLM.Usage")({
   native: Schema.optional(Schema.Record(Schema.String, Schema.Unknown)),
 }) {}
 
-export namespace Usage {
-  /** Sum of every input-side category. Monotonic under the additive contract. */
-  export const totalInput = (usage: Usage) =>
-    (usage.inputTokens ?? 0) + (usage.cacheReadInputTokens ?? 0) + (usage.cacheWriteInputTokens ?? 0)
-
-  /** Sum of every output-side category. Monotonic under the additive contract. */
-  export const totalOutput = (usage: Usage) => (usage.outputTokens ?? 0) + (usage.reasoningTokens ?? 0)
-}
-
 export const RequestStart = Schema.Struct({
   type: Schema.tag("request-start"),
   id: ResponseID,
diff --git a/packages/llm/test/schema.test.ts b/packages/llm/test/schema.test.ts
index 7ef3247f8b..a64b0ff71c 100644
--- a/packages/llm/test/schema.test.ts
+++ b/packages/llm/test/schema.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, test } from "bun:test"
 import { Schema } from "effect"
-import { ContentPart, LLMEvent, LLMRequest, ModelID, ModelLimits, ModelRef, ProviderID, Usage } from "../src/schema"
+import { ContentPart, LLMEvent, LLMRequest, ModelID, ModelLimits, ModelRef, ProviderID } from "../src/schema"
 import { ProviderShared } from "../src/protocols/shared"
 
 const model = new ModelRef({
@@ -53,24 +53,12 @@ describe("llm schema", () => {
 describe("LLM.Usage additive contract", () => {
   test("subtractTokens clamps non-sensical breakdowns to zero", () => {
     // Defense against a provider reporting cached_tokens > prompt_tokens or
-    // reasoning_tokens > completion_tokens. The clamp prevents the negative
-    // values that triggered opencode#26620 from ever entering the pipeline.
+    // reasoning_tokens > completion_tokens — the negative would otherwise
+    // round-trip through the pipeline and crash strict downstream schemas.
     expect(ProviderShared.subtractTokens(5, 3)).toBe(2)
     expect(ProviderShared.subtractTokens(5, 10)).toBe(0)
     expect(ProviderShared.subtractTokens(5, undefined)).toBe(5)
     expect(ProviderShared.subtractTokens(undefined, 3)).toBeUndefined()
     expect(ProviderShared.subtractTokens(undefined, undefined)).toBeUndefined()
   })
-
-  test("totalInput sums every input-side category", () => {
-    expect(Usage.totalInput(new Usage({ inputTokens: 10, cacheReadInputTokens: 3, cacheWriteInputTokens: 2 }))).toBe(15)
-    expect(Usage.totalInput(new Usage({ inputTokens: 10 }))).toBe(10)
-    expect(Usage.totalInput(new Usage({}))).toBe(0)
-  })
-
-  test("totalOutput sums every output-side category", () => {
-    expect(Usage.totalOutput(new Usage({ outputTokens: 7, reasoningTokens: 4 }))).toBe(11)
-    expect(Usage.totalOutput(new Usage({ outputTokens: 7 }))).toBe(7)
-    expect(Usage.totalOutput(new Usage({}))).toBe(0)
-  })
 })