diff --git a/packages/opencode/src/session/llm-native.ts b/packages/opencode/src/session/llm-native.ts
new file mode 100644
index 000000000000..74be5988ee2f
--- /dev/null
+++ b/packages/opencode/src/session/llm-native.ts
@@ -0,0 +1,186 @@
+import type { JsonSchema, LLMRequest, ProviderMetadata } from "@opencode-ai/llm"
+import { LLM, Message, SystemPart, ToolCallPart, ToolDefinition, ToolResultPart } from "@opencode-ai/llm"
+import "@opencode-ai/llm/providers"
+import type { ModelMessage } from "ai"
+import type { Provider } from "@/provider/provider"
+
+type ToolInput = {
+  readonly description?: string
+  readonly inputSchema?: unknown
+}
+
+export type RequestInput = {
+  readonly model: Provider.Model
+  readonly system?: readonly string[]
+  readonly messages: readonly ModelMessage[]
+  readonly tools?: Record<string, ToolInput>
+  readonly toolChoice?: "auto" | "required" | "none"
+  readonly temperature?: number
+  readonly topP?: number
+  readonly topK?: number
+  readonly maxOutputTokens?: number
+  readonly providerOptions?: LLMRequest["providerOptions"]
+  readonly headers?: Record<string, string>
+}
+
+const DEFAULT_BASE_URL: Record<string, string> = {
+  "@ai-sdk/openai": "https://api.openai.com/v1",
+  "@ai-sdk/anthropic": "https://api.anthropic.com/v1",
+  "@ai-sdk/google": "https://generativelanguage.googleapis.com/v1beta",
+  "@ai-sdk/amazon-bedrock": "https://bedrock-runtime.us-east-1.amazonaws.com",
+  "@openrouter/ai-sdk-provider": "https://openrouter.ai/api/v1",
+}
+
+const ROUTE: Record<string, string> = {
+  "@ai-sdk/openai": "openai-responses",
+  "@ai-sdk/azure": "azure-openai-responses",
+  "@ai-sdk/anthropic": "anthropic-messages",
+  "@ai-sdk/google": "gemini",
+  "@ai-sdk/amazon-bedrock": "bedrock-converse",
+  "@ai-sdk/openai-compatible": "openai-compatible-chat",
+  "@openrouter/ai-sdk-provider": "openrouter",
+}
+
+const isRecord = (value: unknown): value is Record<string, unknown> =>
+  typeof value === "object" && value !== null && !Array.isArray(value)
+
+const providerMetadata = (value: unknown): ProviderMetadata | undefined => {
+  if (!isRecord(value)) return undefined
+  const result = Object.fromEntries(
+    Object.entries(value).filter((entry): entry is [string, Record<string, unknown>] => isRecord(entry[1])),
+  )
+  return Object.keys(result).length === 0 ? undefined : result
+}
+
+const textPart = (part: Record<string, unknown>) => ({
+  type: "text" as const,
+  text: typeof part.text === "string" ? part.text : "",
+  providerMetadata: providerMetadata(part.providerOptions),
+})
+
+const mediaPart = (part: Record<string, unknown>) => {
+  if (typeof part.data !== "string" && !(part.data instanceof Uint8Array))
+    throw new Error("Native LLM request adapter only supports file parts with string or Uint8Array data")
+  return {
+    type: "media" as const,
+    mediaType: typeof part.mediaType === "string" ? part.mediaType : "application/octet-stream",
+    data: part.data,
+    filename: typeof part.filename === "string" ? part.filename : undefined,
+  }
+}
+
+const toolResult = (part: Record<string, unknown>) => {
+  const output = isRecord(part.output) ? part.output : { type: "json", value: part.output }
+  const type = output.type === "text" ? "text" : output.type === "error-text" ? "error" : "json"
+  return ToolResultPart.make({
+    id: typeof part.toolCallId === "string" ? part.toolCallId : "",
+    name: typeof part.toolName === "string" ? part.toolName : "",
+    result: "value" in output ? output.value : output,
+    resultType: type,
+    providerExecuted: typeof part.providerExecuted === "boolean" ? part.providerExecuted : undefined,
+    providerMetadata: providerMetadata(part.providerOptions),
+  })
+}
+
+const contentPart = (part: unknown) => {
+  if (!isRecord(part)) throw new Error("Native LLM request adapter only supports object content parts")
+  if (part.type === "text") return textPart(part)
+  if (part.type === "file") return mediaPart(part)
+  if (part.type === "reasoning")
+    return {
+      type: "reasoning" as const,
+      text: typeof part.text === "string" ? part.text : "",
+      providerMetadata: providerMetadata(part.providerOptions),
+    }
+  if (part.type === "tool-call")
+    return ToolCallPart.make({
+      id: typeof part.toolCallId === "string" ? part.toolCallId : "",
+      name: typeof part.toolName === "string" ? part.toolName : "",
+      input: part.input,
+      providerExecuted: typeof part.providerExecuted === "boolean" ? part.providerExecuted : undefined,
+      providerMetadata: providerMetadata(part.providerOptions),
+    })
+  if (part.type === "tool-result") return toolResult(part)
+  throw new Error(`Native LLM request adapter does not support ${String(part.type)} content parts`)
+}
+
+const content = (value: ModelMessage["content"]) =>
+  typeof value === "string" ? [{ type: "text" as const, text: value }] : value.map(contentPart)
+
+const messages = (input: readonly ModelMessage[]) => {
+  const system = input.flatMap((message) => (message.role === "system" ? [SystemPart.make(message.content)] : []))
+  const messages = input.flatMap((message) => {
+    if (message.role === "system") return []
+    return [
+      Message.make({
+        role: message.role,
+        content: content(message.content),
+        native: isRecord(message.providerOptions) ? { providerOptions: message.providerOptions } : undefined,
+      }),
+    ]
+  })
+  return { system, messages }
+}
+
+const schema = (value: unknown): JsonSchema => {
+  if (!isRecord(value)) return { type: "object", properties: {} }
+  if (isRecord(value.jsonSchema)) return value.jsonSchema
+  return value
+}
+
+const tools = (input: Record<string, ToolInput> | undefined): ToolDefinition[] =>
+  Object.entries(input ?? {}).map(([name, item]) =>
+    ToolDefinition.make({
+      name,
+      description: item.description ?? "",
+      inputSchema: schema(item.inputSchema),
+    }),
+  )
+
+const generation = (input: RequestInput) => {
+  const result = {
+    temperature: input.temperature,
+    topP: input.topP,
+    topK: input.topK,
+    maxTokens: input.maxOutputTokens,
+  }
+  return Object.values(result).some((value) => value !== undefined) ? result : undefined
+}
+
+const baseURL = (model: Provider.Model) => {
+  if (model.api.url) return model.api.url
+  const fallback = DEFAULT_BASE_URL[model.api.npm]
+  if (fallback) return fallback
+  throw new Error(`Native LLM request adapter requires a base URL for ${model.providerID}/${model.id}`)
+}
+
+export const model = (model: Provider.Model, headers?: Record<string, string>) => {
+  const route = ROUTE[model.api.npm]
+  if (!route) throw new Error(`Native LLM request adapter does not support provider package ${model.api.npm}`)
+  return LLM.model({
+    id: model.api.id,
+    provider: model.providerID,
+    route,
+    baseURL: baseURL(model),
+    headers: Object.keys({ ...model.headers, ...headers }).length === 0 ? undefined : { ...model.headers, ...headers },
+    limits: {
+      context: model.limit.context,
+      output: model.limit.output,
+    },
+  })
+}
+
+export const request = (input: RequestInput) => {
+  const converted = messages(input.messages)
+  return LLM.request({
+    model: model(input.model, input.headers),
+    system: [...(input.system ?? []).map(SystemPart.make), ...converted.system],
+    messages: converted.messages,
+    tools: tools(input.tools),
+    toolChoice: input.toolChoice,
+    generation: generation(input),
+    providerOptions: input.providerOptions,
+  })
+}
+
+export * as LLMNative from "./llm-native"
diff --git a/packages/opencode/test/session/llm-native.test.ts b/packages/opencode/test/session/llm-native.test.ts
new file mode 100644
index 000000000000..81d4a131190d
--- /dev/null
+++ b/packages/opencode/test/session/llm-native.test.ts
@@ -0,0 +1,234 @@
+import { describe, expect, test } from "bun:test"
+import { jsonSchema, tool, type ModelMessage } from "ai"
+import { LLMNative } from "@/session/llm-native"
+import type { Provider } from "@/provider/provider"
+import { ModelID, ProviderID } from "@/provider/schema"
+
+const baseModel: Provider.Model = {
+  id: ModelID.make("gpt-5-mini"),
+  providerID: ProviderID.make("openai"),
+  api: {
+    id: "gpt-5-mini",
+    url: "https://api.openai.com/v1",
+    npm: "@ai-sdk/openai",
+  },
+  name: "GPT-5 Mini",
+  capabilities: {
+    temperature: true,
+    reasoning: true,
+    attachment: true,
+    toolcall: true,
+    input: {
+      text: true,
+      audio: false,
+      image: true,
+      video: false,
+      pdf: false,
+    },
+    output: {
+      text: true,
+      audio: false,
+      image: false,
+      video: false,
+      pdf: false,
+    },
+    interleaved: false,
+  },
+  cost: {
+    input: 0,
+    output: 0,
+    cache: {
+      read: 0,
+      write: 0,
+    },
+  },
+  limit: {
+    context: 128_000,
+    input: 128_000,
+    output: 32_000,
+  },
+  status: "active",
+  options: {},
+  headers: {
+    "x-model": "model-header",
+  },
+  release_date: "2026-01-01",
+}
+
+describe("session.llm-native.request", () => {
+  test("maps normalized stream inputs to a native LLM request", () => {
+    const messages: ModelMessage[] = [
+      {
+        role: "system",
+        content: "system from messages",
+      },
+      {
+        role: "user",
+        content: [
+          { type: "text", text: "hello", providerOptions: { openai: { cacheControl: { type: "ephemeral" } } } },
+          { type: "file", mediaType: "image/png", filename: "img.png", data: "data:image/png;base64,Zm9v" },
+        ],
+      },
+      {
+        role: "assistant",
+        content: [
+          { type: "reasoning", text: "thinking", providerOptions: { openai: { encryptedContent: "secret" } } },
+          { type: "text", text: "I'll run it" },
+          {
+            type: "tool-call",
+            toolCallId: "call-1",
+            toolName: "bash",
+            input: { command: "ls" },
+            providerOptions: { openai: { itemId: "item-1" } },
+          },
+        ],
+      },
+      {
+        role: "tool",
+        content: [
+          {
+            type: "tool-result",
+            toolCallId: "call-1",
+            toolName: "bash",
+            output: { type: "text", value: "ok" },
+            providerOptions: { openai: { outputId: "output-1" } },
+          },
+        ],
+      },
+    ]
+
+    const request = LLMNative.request({
+      model: baseModel,
+      system: ["agent system"],
+      messages,
+      tools: {
+        bash: tool({
+          description: "Run a shell command",
+          inputSchema: jsonSchema({
+            type: "object",
+            properties: {
+              command: { type: "string" },
+            },
+            required: ["command"],
+          }),
+        }),
+      },
+      toolChoice: "required",
+      temperature: 0.2,
+      topP: 0.9,
+      topK: 40,
+      maxOutputTokens: 1024,
+      providerOptions: { openai: { store: false } },
+      headers: { "x-request": "request-header" },
+    })
+
+    expect(request.model).toMatchObject({
+      id: "gpt-5-mini",
+      provider: "openai",
+      route: "openai-responses",
+      baseURL: "https://api.openai.com/v1",
+      headers: {
+        "x-model": "model-header",
+        "x-request": "request-header",
+      },
+      limits: {
+        context: 128_000,
+        output: 32_000,
+      },
+    })
+    expect(request.system).toEqual([
+      { type: "text", text: "agent system" },
+      { type: "text", text: "system from messages" },
+    ])
+    expect(request.generation).toMatchObject({
+      temperature: 0.2,
+      topP: 0.9,
+      topK: 40,
+      maxTokens: 1024,
+    })
+    expect(request.providerOptions).toEqual({ openai: { store: false } })
+    expect(request.toolChoice).toMatchObject({ type: "required" })
+    expect(request.tools).toMatchObject([
+      {
+        name: "bash",
+        description: "Run a shell command",
+        inputSchema: {
+          type: "object",
+          properties: {
+            command: { type: "string" },
+          },
+          required: ["command"],
+        },
+      },
+    ])
+    expect(request.messages).toMatchObject([
+      {
+        role: "user",
+        content: [
+          { type: "text", text: "hello", providerMetadata: { openai: { cacheControl: { type: "ephemeral" } } } },
+          { type: "media", mediaType: "image/png", filename: "img.png", data: "data:image/png;base64,Zm9v" },
+        ],
+      },
+      {
+        role: "assistant",
+        content: [
+          { type: "reasoning", text: "thinking", providerMetadata: { openai: { encryptedContent: "secret" } } },
+          { type: "text", text: "I'll run it" },
+          {
+            type: "tool-call",
+            id: "call-1",
+            name: "bash",
+            input: { command: "ls" },
+            providerMetadata: { openai: { itemId: "item-1" } },
+          },
+        ],
+      },
+      {
+        role: "tool",
+        content: [
+          {
+            type: "tool-result",
+            id: "call-1",
+            name: "bash",
+            result: { type: "text", value: "ok" },
+            providerMetadata: { openai: { outputId: "output-1" } },
+          },
+        ],
+      },
+    ])
+  })
+
+  test("selects native routes from existing provider packages", () => {
+    expect(
+      LLMNative.model({ ...baseModel, api: { ...baseModel.api, url: "", npm: "@ai-sdk/anthropic" } }),
+    ).toMatchObject({
+      route: "anthropic-messages",
+      baseURL: "https://api.anthropic.com/v1",
+    })
+    expect(LLMNative.model({ ...baseModel, api: { ...baseModel.api, url: "", npm: "@ai-sdk/google" } })).toMatchObject({
+      route: "gemini",
+      baseURL: "https://generativelanguage.googleapis.com/v1beta",
+    })
+    expect(
+      LLMNative.model({ ...baseModel, api: { ...baseModel.api, npm: "@ai-sdk/openai-compatible" } }),
+    ).toMatchObject({
+      route: "openai-compatible-chat",
+      baseURL: "https://api.openai.com/v1",
+    })
+    expect(
+      LLMNative.model({ ...baseModel, api: { ...baseModel.api, url: "", npm: "@openrouter/ai-sdk-provider" } }),
+    ).toMatchObject({
+      route: "openrouter",
+      baseURL: "https://openrouter.ai/api/v1",
+    })
+  })
+
+  test("fails fast for unsupported provider packages", () => {
+    expect(() =>
+      LLMNative.request({
+        model: { ...baseModel, api: { ...baseModel.api, npm: "unknown-provider" } },
+        messages: [],
+      }),
+    ).toThrow("Native LLM request adapter does not support provider package unknown-provider")
+  })
+})