feat(llm): enforce request precedence (#34440)

packages/llm/src/protocols/anthropic-messages.ts

@@ -504,6 +504,7 @@ const lowerThinking = Effect.fn("AnthropicMessages.lowerThinking")(function* (re
 const fromRequest = Effect.fn("AnthropicMessages.fromRequest")(function* (request: LLMRequest) {
   const toolChoice = request.toolChoice ? yield* lowerToolChoice(request.toolChoice) : undefined
   const generation = request.generation
+  const outputLimit = request.model.defaults?.limits?.output ?? request.model.route.defaults.limits?.output ?? 4096
   // Allocate the 4-breakpoint budget in invalidation order: tools → system →
   // messages. Tools live highest in the cache hierarchy, so when callers
   // over-mark we keep their tool hints and shed the message-tail ones first.
@@ -533,7 +534,7 @@ const fromRequest = Effect.fn("AnthropicMessages.fromRequest")(function* (reques
     tools,
     tool_choice: toolChoice,
     stream: true as const,
-    max_tokens: generation?.maxTokens ?? request.model.route.defaults.limits?.output ?? 4096,
+    max_tokens: generation?.maxTokens ?? outputLimit,
     temperature: generation?.temperature,
     top_p: generation?.topP,
     top_k: generation?.topK,

packages/llm/src/route/client.ts

@@ -164,13 +164,16 @@ export interface GenerateMethod {
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/LLMClient") {}
 
-const resolveRequestOptions = (request: LLMRequest) =>
-  LLMRequest.update(request, {
-    generation:
-      mergeGenerationOptions(request.model.route.defaults.generation, request.generation) ?? new GenerationOptions({}),
-    providerOptions: mergeProviderOptions(request.model.route.defaults.providerOptions, request.providerOptions),
-    http: mergeHttpOptions(request.model.route.defaults.http, request.http),
+const resolveRequestOptions = (request: LLMRequest) => {
+  const routeDefaults = request.model.route.defaults
+  const modelDefaults = request.model.defaults
+  const generation = mergeGenerationOptions(routeDefaults.generation, modelDefaults?.generation, request.generation)
+  return LLMRequest.update(request, {
+    generation: generation ?? new GenerationOptions({}),
+    providerOptions: mergeProviderOptions(routeDefaults.providerOptions, modelDefaults?.providerOptions, request.providerOptions),
+    http: mergeHttpOptions(routeDefaults.http, modelDefaults?.http, request.http),
   })
+}
 
 export interface MakeInput<Body, Frame, Event, State> {
   /** Route id used in diagnostics and prepared request metadata. */

packages/llm/test/prepare.test.ts

@@ -0,0 +1,162 @@
+import { describe, expect, test } from "bun:test"
+import { Effect, Schema } from "effect"
+import { HttpClientRequest } from "effect/unstable/http"
+import { LLM, mergeProviderOptions } from "../src"
+import { AnthropicMessages, OpenAIChat } from "../src/protocols"
+import { Auth, LLMClient } from "../src/route"
+import { it } from "./lib/effect"
+import { dynamicResponse } from "./lib/http"
+import { deltaChunk } from "./lib/openai-chunks"
+import { sseEvents } from "./lib/sse"
+
+const TargetJson = Schema.fromJsonString(Schema.Unknown)
+const decodeJson = Schema.decodeUnknownSync(TargetJson)
+
+describe("request option precedence", () => {
+  test("deep-merges provider option records and replaces arrays, primitives, and null", () => {
+    const merged = mergeProviderOptions(
+      {
+        openai: {
+          include: ["route"],
+          metadata: { route: true, shared: "route" },
+          nullable: "route",
+          primitive: "route",
+        },
+      },
+      {
+        openai: {
+          include: ["model"],
+          metadata: { model: true, shared: "model" },
+          nullable: null,
+          primitive: "model",
+        },
+      },
+      { openai: { metadata: { request: true }, primitive: false } },
+    )
+
+    expect(merged).toEqual({
+      openai: {
+        include: ["model"],
+        metadata: { route: true, model: true, request: true, shared: "model" },
+        nullable: null,
+        primitive: false,
+      },
+    })
+  })
+
+  it.effect("prepares bodies with route defaults, model defaults, and call options in order", () =>
+    Effect.gen(function* () {
+      const route = OpenAIChat.route.with({
+        endpoint: { baseURL: "https://api.openai.test/v1/" },
+        auth: Auth.bearer("test"),
+        generation: { maxTokens: 10, temperature: 1, stop: ["route"] },
+        providerOptions: { openai: { store: false, reasoningEffort: "low" } },
+      })
+      const model = route.model({
+        id: "gpt-4o-mini",
+        defaults: {
+          generation: { maxTokens: 20, temperature: 0.5, frequencyPenalty: 0.25, stop: ["model"] },
+          providerOptions: { openai: { reasoningEffort: "medium" } },
+        },
+      })
+      const prepared = yield* LLMClient.prepare<OpenAIChat.OpenAIChatBody>(
+        LLM.request({
+          model,
+          prompt: "Say hello.",
+          generation: { maxTokens: 30, topP: 0.9, stop: ["request"] },
+          providerOptions: { openai: { store: true } },
+        }),
+      )
+
+      expect(prepared.body).toMatchObject({
+        model: "gpt-4o-mini",
+        stream: true,
+        max_tokens: 30,
+        temperature: 0.5,
+        top_p: 0.9,
+        frequency_penalty: 0.25,
+        store: true,
+        reasoning_effort: "medium",
+      })
+      expect(prepared.body.stop).toEqual(["request"])
+    }),
+  )
+
+  it.effect("applies model HTTP defaults before request HTTP overlays", () =>
+    LLMClient.generate(
+      LLM.request({
+        model: OpenAIChat.route
+          .with({
+            endpoint: { baseURL: "https://api.openai.test/v1/" },
+            auth: Auth.bearer("fresh-key"),
+            http: {
+              body: { metadata: { route: true, shared: "route" }, value: "route" },
+              headers: { "x-route": "route", "x-shared": "route" },
+              query: { route: "1", shared: "route" },
+            },
+          })
+          .model({
+            id: "gpt-4o-mini",
+            defaults: {
+              http: {
+                body: { metadata: { model: true, shared: "model" }, value: "model" },
+                headers: { "x-model": "model", "x-shared": "model" },
+                query: { model: "1", shared: "model" },
+              },
+            },
+          }),
+        prompt: "Say hello.",
+        http: {
+          body: { metadata: { request: true }, value: null },
+          headers: { "x-request": "request" },
+          query: { request: "1" },
+        },
+      }),
+    ).pipe(
+      Effect.provide(
+        dynamicResponse((input) =>
+          Effect.gen(function* () {
+            const web = yield* HttpClientRequest.toWeb(input.request).pipe(Effect.orDie)
+            const url = new URL(web.url)
+            expect(url.searchParams.get("route")).toBe("1")
+            expect(url.searchParams.get("model")).toBe("1")
+            expect(url.searchParams.get("request")).toBe("1")
+            expect(url.searchParams.get("shared")).toBe("model")
+            expect(web.headers.get("authorization")).toBe("Bearer fresh-key")
+            expect(web.headers.get("x-route")).toBe("route")
+            expect(web.headers.get("x-model")).toBe("model")
+            expect(web.headers.get("x-request")).toBe("request")
+            expect(web.headers.get("x-shared")).toBe("model")
+            expect(decodeJson(input.text)).toMatchObject({
+              metadata: { route: true, model: true, request: true, shared: "model" },
+              value: null,
+            })
+            return input.respond(sseEvents(deltaChunk({}, "stop")), {
+              headers: { "content-type": "text/event-stream" },
+            })
+          }),
+        ),
+      ),
+    ),
+  )
+
+  it.effect("uses model output limits after route limits and before call maxTokens", () =>
+    Effect.gen(function* () {
+      const route = AnthropicMessages.route.with({
+        endpoint: { baseURL: "https://api.anthropic.test/v1/" },
+        auth: Auth.header("x-api-key", "test"),
+        limits: { output: 128 },
+      })
+      const model = route.model({ id: "claude-sonnet-4-5", defaults: { limits: { output: 64 } } })
+      const withoutMaxTokens = yield* LLMClient.prepare<AnthropicMessages.AnthropicMessagesBody>(
+        LLM.request({ model, prompt: "Say hello.", cache: "none" }),
+      )
+      const withMaxTokens = yield* LLMClient.prepare<AnthropicMessages.AnthropicMessagesBody>(
+        LLM.request({ model, prompt: "Say hello.", cache: "none", generation: { maxTokens: 32 } }),
+      )
+
+      expect(withoutMaxTokens.body.max_tokens).toBe(64)
+      expect(withMaxTokens.body.max_tokens).toBe(32)
+    }),
+  )
+})