diff --git a/packages/types/src/__tests__/provider-settings.test.ts b/packages/types/src/__tests__/provider-settings.test.ts
index b29a93ca3e..6a5294ab66 100644
--- a/packages/types/src/__tests__/provider-settings.test.ts
+++ b/packages/types/src/__tests__/provider-settings.test.ts
@@ -22,6 +22,39 @@ describe("provider settings discriminated union", () => {
 	})
 })
 
+describe("OpenAI-compatible extra body settings", () => {
+	it("accepts a JSON object with provider-specific nested fields", () => {
+		const settings = {
+			apiProvider: providerIdentifiers.openai,
+			openAiExtraBody: JSON.stringify({ metadata: { completion_window: "balanced" }, store: false }),
+		}
+
+		expect(providerSettingsSchemaDiscriminated.parse(settings)).toEqual(settings)
+		expect(PROVIDER_SETTINGS_KEYS).toContain("openAiExtraBody")
+	})
+
+	it.each(["not json", "[]", "null", '"value"'])("rejects non-object JSON: %s", (openAiExtraBody) => {
+		expect(
+			providerSettingsSchemaDiscriminated.safeParse({
+				apiProvider: providerIdentifiers.openai,
+				openAiExtraBody,
+			}).success,
+		).toBe(false)
+	})
+
+	it.each(["model", "messages", "stream", "tools", "max_tokens", "__proto__"])(
+		"rejects the reserved request key %s",
+		(reservedKey) => {
+			expect(
+				providerSettingsSchemaDiscriminated.safeParse({
+					apiProvider: providerIdentifiers.openai,
+					openAiExtraBody: JSON.stringify({ [reservedKey]: "override" }),
+				}).success,
+			).toBe(false)
+		},
+	)
+})
+
 describe("OpenAI Codex provider settings", () => {
 	it("preserves the Fast preference in general and provider-specific schemas", () => {
 		const settings = {
diff --git a/packages/types/src/provider-settings.ts b/packages/types/src/provider-settings.ts
index 4a432970c2..c09c9f8fe5 100644
--- a/packages/types/src/provider-settings.ts
+++ b/packages/types/src/provider-settings.ts
@@ -4,6 +4,8 @@ import { providerDefinitionList, type ProviderDefinition } from "./provider-sett
 import { API_PROVIDER_FIELD, SETTINGS_SHAPE_FIELD } from "./provider-settings/common.js"
 export {
 	OPEN_AI_CODEX_SERVICE_TIER_KEY,
+	OPENAI_EXTRA_BODY_RESERVED_KEYS,
+	parseOpenAiExtraBody,
 	kimiCodeAuthMethodSchema,
 	type KimiCodeAuthMethod,
 	nanoGptDefaultRoutingPreference,
diff --git a/packages/types/src/provider-settings/index.ts b/packages/types/src/provider-settings/index.ts
index 225b54fc29..17a3f36baf 100644
--- a/packages/types/src/provider-settings/index.ts
+++ b/packages/types/src/provider-settings/index.ts
@@ -37,6 +37,7 @@ import { basetenProviderDefinition } from "./baseten.js"
 import type { ProviderDefinition } from "./common.js"
 
 export { OPEN_AI_CODEX_SERVICE_TIER_KEY } from "./openai-codex.js"
+export { OPENAI_EXTRA_BODY_RESERVED_KEYS, parseOpenAiExtraBody } from "./openai.js"
 export { kimiCodeAuthMethodSchema, type KimiCodeAuthMethod } from "./kimi-code.js"
 export { zaiApiLineSchema, type ZaiApiLine } from "./zai.js"
 export {
diff --git a/packages/types/src/provider-settings/openai.ts b/packages/types/src/provider-settings/openai.ts
index 651d90f60d..2176a981f6 100644
--- a/packages/types/src/provider-settings/openai.ts
+++ b/packages/types/src/provider-settings/openai.ts
@@ -6,6 +6,72 @@ import { baseProviderSettingsShape, createModelIdAccessor, createProviderDefinit
 
 export const OPEN_AI_MODEL_ID_FIELD = "openAiModelId"
 
+export const OPENAI_EXTRA_BODY_RESERVED_KEYS = [
+	"__proto__",
+	"constructor",
+	"max_completion_tokens",
+	"max_tokens",
+	"messages",
+	"model",
+	"parallel_tool_calls",
+	"prototype",
+	"reasoning",
+	"reasoning_effort",
+	"stream",
+	"stream_options",
+	"temperature",
+	"tool_choice",
+	"tools",
+] as const
+
+type OpenAiExtraBodyParseResult =
+	| { success: true; data: Record<string, unknown> }
+	| {
+			success: false
+			reason: "invalidJson" | "objectRequired" | "reservedKeys"
+			data: Record<string, unknown>
+			reservedKeys?: string[]
+	  }
+
+export function parseOpenAiExtraBody(value: string | undefined): OpenAiExtraBodyParseResult {
+	if (!value?.trim()) {
+		return { success: true, data: {} }
+	}
+
+	let parsed: unknown
+	try {
+		parsed = JSON.parse(value)
+	} catch {
+		return { success: false, reason: "invalidJson", data: {} }
+	}
+
+	if (parsed === null || typeof parsed !== "object" || Array.isArray(parsed)) {
+		return { success: false, reason: "objectRequired", data: {} }
+	}
+
+	const entries = Object.entries(parsed)
+	const reservedKeys = entries
+		.map(([key]) => key)
+		.filter((key) => (OPENAI_EXTRA_BODY_RESERVED_KEYS as readonly string[]).includes(key))
+	const data = Object.fromEntries(entries.filter(([key]) => !reservedKeys.includes(key)))
+
+	if (reservedKeys.length > 0) {
+		return { success: false, reason: "reservedKeys", reservedKeys, data }
+	}
+
+	return { success: true, data }
+}
+
+const openAiExtraBodySchema = z
+	.string()
+	.superRefine((value, ctx) => {
+		const result = parseOpenAiExtraBody(value)
+		if (!result.success) {
+			ctx.addIssue({ code: "custom", message: result.reason })
+		}
+	})
+	.optional()
+
 export const openAiProviderDefinition = createProviderDefinition({
 	apiProvider: providerIdentifiers.openai,
 	modelIdKey: OPEN_AI_MODEL_ID_FIELD,
@@ -22,5 +88,6 @@ export const openAiProviderDefinition = createProviderDefinition({
 		openAiStreamingEnabled: z.boolean().optional(),
 		openAiHostHeader: z.string().optional(), // Keep temporarily for backward compatibility during migration.
 		openAiHeaders: z.record(z.string(), z.string()).optional(),
+		openAiExtraBody: openAiExtraBodySchema,
 	},
 })
diff --git a/src/api/providers/__tests__/openai.spec.ts b/src/api/providers/__tests__/openai.spec.ts
index 38550533a5..a41bd20648 100644
--- a/src/api/providers/__tests__/openai.spec.ts
+++ b/src/api/providers/__tests__/openai.spec.ts
@@ -261,6 +261,45 @@ describe("OpenAiHandler", () => {
 			expect(textChunks[0].text).toBe("Test response")
 		})
 
+		it("adds Extra Body fields to streaming requests without allowing reserved field overrides", async () => {
+			const extraBodyHandler = new OpenAiHandler({
+				...mockOptions,
+				openAiExtraBody: JSON.stringify({
+					metadata: { completion_window: "balanced" },
+					model: "overridden-model",
+					messages: [],
+					stream: false,
+				}),
+			})
+
+			await collectStream(extraBodyHandler.createMessage(systemPrompt, messages))
+
+			expect(mockCreate).toHaveBeenCalledWith(
+				expect.objectContaining({
+					metadata: { completion_window: "balanced" },
+					model: mockOptions.openAiModelId,
+					stream: true,
+					messages: expect.arrayContaining([expect.objectContaining({ role: "user" })]),
+				}),
+				{},
+			)
+		})
+
+		it("adds Extra Body fields to non-streaming requests", async () => {
+			const extraBodyHandler = new OpenAiHandler({
+				...mockOptions,
+				openAiStreamingEnabled: false,
+				openAiExtraBody: JSON.stringify({ metadata: { completion_window: "balanced" } }),
+			})
+
+			await collectStream(extraBodyHandler.createMessage(systemPrompt, messages))
+
+			expect(mockCreate).toHaveBeenCalledWith(
+				expect.objectContaining({ metadata: { completion_window: "balanced" } }),
+				{},
+			)
+		})
+
 		it("streams reasoning chunks from delta.reasoning_content", async () => {
 			mockCreate.mockImplementationOnce(async () =>
 				asyncStreamFrom([
@@ -843,6 +882,20 @@ describe("OpenAiHandler", () => {
 			)
 		})
 
+		it("adds Extra Body fields to single-completion requests", async () => {
+			const extraBodyHandler = new OpenAiHandler({
+				...mockOptions,
+				openAiExtraBody: JSON.stringify({ metadata: { completion_window: "balanced" } }),
+			})
+
+			await extraBodyHandler.completePrompt("Test prompt")
+
+			expect(mockCreate).toHaveBeenCalledWith(
+				expect.objectContaining({ metadata: { completion_window: "balanced" } }),
+				{},
+			)
+		})
+
 		it("should handle API errors", async () => {
 			mockCreate.mockRejectedValueOnce(new Error("API Error"))
 			await expect(handler.completePrompt("Test prompt")).rejects.toThrow("OpenAI completion error: API Error")
@@ -1103,6 +1156,21 @@ describe("OpenAiHandler", () => {
 			)
 		})
 
+		it.each([true, false])("adds Extra Body fields to O3 requests when streaming is %s", async (streaming) => {
+			const o3Handler = new OpenAiHandler({
+				...o3Options,
+				openAiStreamingEnabled: streaming,
+				openAiExtraBody: JSON.stringify({ metadata: { completion_window: "balanced" } }),
+			})
+
+			await collectStream(o3Handler.createMessage("system", []))
+
+			expect(mockCreate).toHaveBeenCalledWith(
+				expect.objectContaining({ metadata: { completion_window: "balanced" } }),
+				{},
+			)
+		})
+
 		it("should handle tool calls with O3 model in streaming mode", async () => {
 			const o3Handler = new OpenAiHandler(o3Options)
 
diff --git a/src/api/providers/openai.ts b/src/api/providers/openai.ts
index 5588dd37d6..5132b02450 100644
--- a/src/api/providers/openai.ts
+++ b/src/api/providers/openai.ts
@@ -10,6 +10,7 @@ import {
 	openAiModelInfoSaneDefaults,
 	DEEP_SEEK_DEFAULT_TEMPERATURE,
 	OPENAI_AZURE_AI_INFERENCE_PATH,
+	parseOpenAiExtraBody,
 } from "@roo-code/types"
 
 import type { ApiHandlerOptions } from "../../shared/api"
@@ -34,10 +35,12 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 	protected options: ApiHandlerOptions
 	protected client: OpenAI
 	private readonly providerName = "OpenAI"
+	private readonly extraBody: Record<string, unknown>
 
 	constructor(options: ApiHandlerOptions) {
 		super()
 		this.options = options
+		this.extraBody = parseOpenAiExtraBody(options.openAiExtraBody).data
 
 		const baseURL = this.options.openAiBaseUrl || "https://api.openai.com/v1"
 		const apiKey = this.options.openAiApiKey ?? NOT_PROVIDED
@@ -152,7 +155,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 
 			const isGrokXAI = this._isGrokXAI(this.options.openAiBaseUrl)
 
-			const requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsStreaming = {
+			let requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsStreaming = {
 				model: modelId,
 				// Some OpenAI-Compatible models (e.g. claude-opus-4-7, claude-opus-4-8) reject
 				// `temperature` as deprecated/unsupported, so honor the model's `supportsTemperature`
@@ -174,6 +177,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 
 			// Add max_tokens if needed
 			this.addMaxTokensIfNeeded(requestOptions, modelInfo)
+			requestOptions = this.withExtraBody(requestOptions)
 
 			let stream
 			try {
@@ -227,7 +231,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 				yield this.processUsageMetrics(lastUsage, modelInfo)
 			}
 		} else {
-			const requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsNonStreaming = {
+			let requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsNonStreaming = {
 				model: modelId,
 				messages: deepseekReasoner
 					? convertToR1Format([{ role: "user", content: systemPrompt }, ...messages])
@@ -240,6 +244,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 
 			// Add max_tokens if needed
 			this.addMaxTokensIfNeeded(requestOptions, modelInfo)
+			requestOptions = this.withExtraBody(requestOptions)
 
 			let response
 			try {
@@ -304,13 +309,14 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 			const model = this.getModel()
 			const modelInfo = model.info
 
-			const requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsNonStreaming = {
+			let requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsNonStreaming = {
 				model: model.id,
 				messages: [{ role: "user", content: prompt }],
 			}
 
 			// Add max_tokens if needed
 			this.addMaxTokensIfNeeded(requestOptions, modelInfo)
+			requestOptions = this.withExtraBody(requestOptions)
 
 			let response
 			try {
@@ -350,7 +356,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 		if (this.options.openAiStreamingEnabled ?? true) {
 			const isGrokXAI = this._isGrokXAI(this.options.openAiBaseUrl)
 
-			const requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsStreaming = {
+			let requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsStreaming = {
 				model: modelId,
 				messages: [
 					{
@@ -373,6 +379,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 			// but they do support max_completion_tokens (the modern OpenAI parameter)
 			// This allows O3 models to limit response length when includeMaxTokens is enabled
 			this.addMaxTokensIfNeeded(requestOptions, modelInfo)
+			requestOptions = this.withExtraBody(requestOptions)
 
 			let stream
 			try {
@@ -386,7 +393,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 
 			yield* this.handleStreamResponse(stream)
 		} else {
-			const requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsNonStreaming = {
+			let requestOptions: OpenAI.Chat.Completions.ChatCompletionCreateParamsNonStreaming = {
 				model: modelId,
 				messages: [
 					{
@@ -407,6 +414,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 			// but they do support max_completion_tokens (the modern OpenAI parameter)
 			// This allows O3 models to limit response length when includeMaxTokens is enabled
 			this.addMaxTokensIfNeeded(requestOptions, modelInfo)
+			requestOptions = this.withExtraBody(requestOptions)
 
 			let response
 			try {
@@ -543,6 +551,10 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 			requestOptions.max_completion_tokens = this.options.modelMaxTokens || modelInfo.maxTokens
 		}
 	}
+
+	private withExtraBody<T extends object>(requestOptions: T): T {
+		return { ...this.extraBody, ...requestOptions }
+	}
 }
 
 export async function getOpenAiModels(baseUrl?: string, apiKey?: string, openAiHeaders?: Record<string, string>) {
diff --git a/src/core/config/__tests__/ProviderSettingsManager.spec.ts b/src/core/config/__tests__/ProviderSettingsManager.spec.ts
index b7a0a9595c..798296eef5 100644
--- a/src/core/config/__tests__/ProviderSettingsManager.spec.ts
+++ b/src/core/config/__tests__/ProviderSettingsManager.spec.ts
@@ -484,6 +484,36 @@ describe("ProviderSettingsManager", () => {
 			},
 		)
 
+		it("persists OpenAI-compatible Extra Body only on OpenAI-compatible profiles", async () => {
+			mockSecrets.get.mockResolvedValue(
+				JSON.stringify({
+					currentApiConfigName: "default",
+					apiConfigs: { default: {} },
+					modeApiConfigs: {},
+				}),
+			)
+			const openAiExtraBody = JSON.stringify({ metadata: { completion_window: "balanced" } })
+
+			await providerSettingsManager.saveConfig("sail", {
+				apiProvider: providerIdentifiers.openai,
+				openAiModelId: "zai-org/GLM-5.2-FP8",
+				openAiExtraBody,
+			})
+
+			let storedProfiles = JSON.parse(mockSecrets.store.mock.calls.at(-1)?.[1])
+			expect(storedProfiles.apiConfigs.sail).toMatchObject({ openAiExtraBody })
+
+			mockSecrets.get.mockResolvedValue(JSON.stringify(storedProfiles))
+			await providerSettingsManager.saveConfig("anthropic", {
+				apiProvider: providerIdentifiers.anthropic,
+				apiKey: "test-key",
+				openAiExtraBody,
+			})
+
+			storedProfiles = JSON.parse(mockSecrets.store.mock.calls.at(-1)?.[1])
+			expect(storedProfiles.apiConfigs.anthropic).not.toHaveProperty("openAiExtraBody")
+		})
+
 		it("should only save provider relevant settings", async () => {
 			mockSecrets.get.mockResolvedValue(
 				JSON.stringify({
diff --git a/webview-ui/src/components/settings/__tests__/ApiOptions.spec.tsx b/webview-ui/src/components/settings/__tests__/ApiOptions.spec.tsx
index c625650845..bd4fe95e0f 100644
--- a/webview-ui/src/components/settings/__tests__/ApiOptions.spec.tsx
+++ b/webview-ui/src/components/settings/__tests__/ApiOptions.spec.tsx
@@ -15,6 +15,9 @@ vi.mock("@vscode/webview-ui-toolkit/react", () => ({
 			<input type="text" value={value} onChange={onBlur} />
 		</div>
 	),
+	VSCodeTextArea: ({ value, onInput, ...props }: any) => (
+		<textarea value={value} onChange={(event) => onInput?.(event)} {...props} />
+	),
 	VSCodeLink: ({ children, href }: any) => <a href={href}>{children}</a>,
 	VSCodeRadio: ({ value, checked }: any) => <input type="radio" value={value} checked={checked} />,
 	VSCodeRadioGroup: ({ children }: any) => <div>{children}</div>,
diff --git a/webview-ui/src/components/settings/providers/OpenAICompatible.tsx b/webview-ui/src/components/settings/providers/OpenAICompatible.tsx
index 7870b21f32..ec8bd0039a 100644
--- a/webview-ui/src/components/settings/providers/OpenAICompatible.tsx
+++ b/webview-ui/src/components/settings/providers/OpenAICompatible.tsx
@@ -1,7 +1,7 @@
-import { useState, useCallback, useEffect } from "react"
+import { useState, useCallback, useEffect, type FormEvent } from "react"
 import { useEvent } from "react-use"
 import { Checkbox } from "vscrui"
-import { VSCodeButton, VSCodeTextField } from "@vscode/webview-ui-toolkit/react"
+import { VSCodeButton, VSCodeTextArea, VSCodeTextField } from "@vscode/webview-ui-toolkit/react"
 
 import {
 	type ProviderSettings,
@@ -13,6 +13,7 @@ import {
 	isAzureOpenAiBaseUrl,
 	openAiModelInfoSaneDefaults,
 	OpenAiModelsMessageType,
+	parseOpenAiExtraBody,
 } from "@roo-code/types"
 
 import { useAppTranslation } from "@src/i18n/TranslationContext"
@@ -54,6 +55,14 @@ export const OpenAICompatible = ({
 		const headers = apiConfiguration?.openAiHeaders || {}
 		return Object.entries(headers)
 	})
+	const extraBodyResult = parseOpenAiExtraBody(apiConfiguration.openAiExtraBody)
+	const extraBodyError = extraBodyResult.success
+		? undefined
+		: extraBodyResult.reason === "reservedKeys"
+			? t("settings:validation.openAiExtraBody.reservedKeys", {
+					keys: extraBodyResult.reservedKeys?.join(", ") ?? "",
+				})
+			: t(`settings:validation.openAiExtraBody.${extraBodyResult.reason}`)
 
 	const handleAddCustomHeader = useCallback(() => {
 		// Only update the local state to show the new row in the UI.
@@ -112,6 +121,14 @@ export const OpenAICompatible = ({
 		[setApiConfigurationField],
 	)
 
+	const handleExtraBodyChange = useCallback(
+		(event: Event | FormEvent<HTMLElement>) => {
+			const target = event.currentTarget as (HTMLElement & { value?: string }) | null
+			setApiConfigurationField("openAiExtraBody", target?.value ?? "")
+		},
+		[setApiConfigurationField],
+	)
+
 	const onMessage = useCallback((event: MessageEvent) => {
 		const message: ExtensionMessage = event.data
 
@@ -251,6 +268,36 @@ export const OpenAICompatible = ({
 				)}
 			</div>
 
+			<div className="mb-4">
+				<label id="openai-extra-body-label" className="block font-medium mb-1">
+					{t("settings:providers.extraBody")}
+				</label>
+				<div id="openai-extra-body-description" className="text-sm text-vscode-descriptionForeground mb-2">
+					{t("settings:providers.extraBodyDescription")}
+				</div>
+				<VSCodeTextArea
+					resize="vertical"
+					rows={5}
+					value={apiConfiguration.openAiExtraBody ?? ""}
+					onInput={handleExtraBodyChange}
+					placeholder={'{\n  "metadata": {\n    "completion_window": "balanced"\n  }\n}'}
+					className="w-full font-mono"
+					aria-labelledby="openai-extra-body-label"
+					aria-describedby={
+						extraBodyError
+							? "openai-extra-body-description openai-extra-body-error"
+							: "openai-extra-body-description"
+					}
+					aria-invalid={extraBodyError ? "true" : undefined}
+					data-testid="openai-extra-body-input"
+				/>
+				{extraBodyError && (
+					<div id="openai-extra-body-error" className="text-sm text-vscode-errorForeground mt-1" role="alert">
+						{extraBodyError}
+					</div>
+				)}
+			</div>
+
 			<div className="flex flex-col gap-1">
 				<Checkbox
 					checked={apiConfiguration.enableReasoningEffort ?? false}
diff --git a/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.spec.tsx b/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.spec.tsx
index 196d067755..cce7ae1ace 100644
--- a/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.spec.tsx
+++ b/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.spec.tsx
@@ -18,7 +18,7 @@ vi.mock("vscrui", () => ({
 	),
 }))
 
-// Mock the VSCodeTextField and VSCodeButton components
+// Mock the VS Code form components
 vi.mock("@vscode/webview-ui-toolkit/react", () => ({
 	VSCodeTextField: ({
 		children,
@@ -52,6 +52,12 @@ vi.mock("@vscode/webview-ui-toolkit/react", () => ({
 			{children}
 		</button>
 	),
+	VSCodeTextArea: ({ value, onInput, children, ...rest }: any) => (
+		<label>
+			{children}
+			<textarea value={value} onChange={(event) => onInput?.(event)} {...rest} />
+		</label>
+	),
 }))
 
 // Mock the translation hook
@@ -429,4 +435,39 @@ describe("OpenAICompatible Component - includeMaxTokens checkbox", () => {
 			})
 		})
 	})
+
+	describe("Extra Body", () => {
+		it("renders the saved JSON and updates the cached provider field", () => {
+			const openAiExtraBody = JSON.stringify({ metadata: { completion_window: "balanced" } }, null, 2)
+
+			render(
+				<OpenAICompatible
+					apiConfiguration={{ openAiExtraBody } as ProviderSettings}
+					setApiConfigurationField={mockSetApiConfigurationField}
+					organizationAllowList={mockOrganizationAllowList}
+				/>,
+			)
+
+			const input = screen.getByTestId("openai-extra-body-input")
+			expect(input).toHaveValue(openAiExtraBody)
+
+			fireEvent.change(input, { target: { value: '{"store":false}' } })
+
+			expect(mockSetApiConfigurationField).toHaveBeenCalledWith("openAiExtraBody", '{"store":false}')
+		})
+
+		it("marks invalid JSON and describes the validation error", () => {
+			render(
+				<OpenAICompatible
+					apiConfiguration={{ openAiExtraBody: "not json" } as ProviderSettings}
+					setApiConfigurationField={mockSetApiConfigurationField}
+					organizationAllowList={mockOrganizationAllowList}
+				/>,
+			)
+
+			const input = screen.getByTestId("openai-extra-body-input")
+			expect(input).toHaveAttribute("aria-invalid", "true")
+			expect(screen.getByText("settings:validation.openAiExtraBody.invalidJson")).toBeInTheDocument()
+		})
+	})
 })
diff --git a/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.fixture.tsx b/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.fixture.tsx
index a84a3a056f..e3d73cee80 100644
--- a/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.fixture.tsx
+++ b/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.fixture.tsx
@@ -38,7 +38,14 @@ const apiConfiguration: ProviderSettings = {
 	openAiUseAzure: true,
 }
 
-export const OpenAICompatibleAzureFixture = () => (
+const extraBodyApiConfiguration: ProviderSettings = {
+	apiProvider: "openai",
+	openAiBaseUrl: "https://api.sailresearch.com/v1",
+	openAiModelId: "zai-org/GLM-5.2-FP8",
+	openAiExtraBody: JSON.stringify({ metadata: { completion_window: "balanced" } }, null, 2),
+}
+
+const Providers = ({ children }: React.PropsWithChildren) => (
 	<PlaywrightTranslationContext.Provider
 		value={{
 			t: (key) => translations[key] ?? key,
@@ -50,17 +57,34 @@ export const OpenAICompatibleAzureFixture = () => (
 				i18n: null as unknown as typeof import("../../../../i18n/setup").default,
 			}}>
 			<QueryClientProvider client={queryClient}>
-				<TooltipProvider>
-					<div className="h-[295px] w-[480px] overflow-hidden bg-vscode-editor-background p-4 text-vscode-foreground">
-						<OpenAICompatible
-							apiConfiguration={apiConfiguration}
-							setApiConfigurationField={() => {}}
-							organizationAllowList={{ allowAll: true, providers: {} }}
-							simplifySettings
-						/>
-					</div>
-				</TooltipProvider>
+				<TooltipProvider>{children}</TooltipProvider>
 			</QueryClientProvider>
 		</AppTranslationContext.Provider>
 	</PlaywrightTranslationContext.Provider>
 )
+
+export const OpenAICompatibleAzureFixture = () => (
+	<Providers>
+		<div className="h-[295px] w-[480px] overflow-hidden bg-vscode-editor-background p-4 text-vscode-foreground">
+			<OpenAICompatible
+				apiConfiguration={apiConfiguration}
+				setApiConfigurationField={() => {}}
+				organizationAllowList={{ allowAll: true, providers: {} }}
+				simplifySettings
+			/>
+		</div>
+	</Providers>
+)
+
+export const OpenAICompatibleExtraBodyFixture = () => (
+	<Providers>
+		<div className="w-[480px] bg-vscode-editor-background p-4 text-vscode-foreground">
+			<OpenAICompatible
+				apiConfiguration={extraBodyApiConfiguration}
+				setApiConfigurationField={() => {}}
+				organizationAllowList={{ allowAll: true, providers: {} }}
+				simplifySettings
+			/>
+		</div>
+	</Providers>
+)
diff --git a/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.tsx b/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.tsx
index 3cb085485a..2fbfa00ad2 100644
--- a/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.tsx
+++ b/webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.visual.tsx
@@ -1,11 +1,12 @@
 import React from "react"
 
 import { expect, test } from "../../../../../playwright/coverage-fixture"
-import { OpenAICompatibleAzureFixture } from "./OpenAICompatible.visual.fixture"
+import { applyVisualTheme, visualThemes } from "../../../../../playwright/themes"
+import { OpenAICompatibleAzureFixture, OpenAICompatibleExtraBodyFixture } from "./OpenAICompatible.visual.fixture"
 
 test("renders Azure OpenAI endpoint and deployment guidance in the VS Code dark theme", async ({ mount, page }) => {
-	// The full provider bundle leaves a bare Zod reference after CT tree-shaking.
-	await page.evaluate(() => Object.assign(globalThis, { z: undefined }))
+	// The full provider bundle leaves bare Zod references after CT tree-shaking.
+	await page.evaluate(() => Object.assign(globalThis, { z: undefined, z$1: undefined }))
 	const component = await mount(<OpenAICompatibleAzureFixture />)
 
 	await component.evaluate((element) => {
@@ -32,3 +33,20 @@ test("renders Azure OpenAI endpoint and deployment guidance in the VS Code dark
 
 	await expect(component).toHaveScreenshot("openai-compatible-azure-guidance-dark.png")
 })
+
+for (const theme of visualThemes) {
+	test(`renders a populated Extra Body editor in the VS Code ${theme.name} theme`, async ({ mount, page }) => {
+		await applyVisualTheme(page, theme)
+		await page.evaluate(() => Object.assign(globalThis, { z: undefined, z$1: undefined }))
+		const component = await mount(<OpenAICompatibleExtraBodyFixture />)
+
+		await expect.poll(() => component.getByTestId("openai-extra-body-input").isVisible()).toBe(true)
+
+		await component.evaluate(async () => {
+			await document.fonts.ready
+			await new Promise<void>((resolve) => requestAnimationFrame(() => resolve()))
+		})
+
+		await expect(component).toHaveScreenshot(`openai-compatible-extra-body-${theme.name}.png`)
+	})
+}
diff --git a/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-dark.png b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-dark.png
new file mode 100644
index 0000000000..bc3061950a
Binary files /dev/null and b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-dark.png differ
diff --git a/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-high-contrast-light.png b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-high-contrast-light.png
new file mode 100644
index 0000000000..47af9cc5db
Binary files /dev/null and b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-high-contrast-light.png differ
diff --git a/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-high-contrast.png b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-high-contrast.png
new file mode 100644
index 0000000000..f48dc7205b
Binary files /dev/null and b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-high-contrast.png differ
diff --git a/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-light.png b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-light.png
new file mode 100644
index 0000000000..7b360eaeab
Binary files /dev/null and b/webview-ui/src/components/settings/providers/__tests__/__screenshots__/openai-compatible-extra-body-light.png differ
diff --git a/webview-ui/src/i18n/locales/ca/settings.json b/webview-ui/src/i18n/locales/ca/settings.json
index 52805e74e8..762a1290af 100644
--- a/webview-ui/src/i18n/locales/ca/settings.json
+++ b/webview-ui/src/i18n/locales/ca/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nom de la capçalera",
 		"headerValue": "Valor de la capçalera",
 		"noCustomHeaders": "No hi ha capçaleres personalitzades definides. Feu clic al botó + per afegir-ne una.",
+		"extraBody": "Cos addicional",
+		"extraBodyDescription": "Objecte JSON opcional que es combina amb els cossos de les sol·licituds API. Els camps gestionats per Zoo Code, com ara model, messages, tools i stream, no es poden sobreescriure. No inclogueu secrets.",
 		"unboundApiKey": "Clau API de Unbound",
 		"getUnboundApiKey": "Obtenir clau API de Unbound",
 		"requestyApiKey": "Clau API de Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "Heu de proporcionar un ID de model vàlid.",
 		"modelSelector": "Heu de proporcionar un selector de model vàlid.",
 		"openAi": "Heu de proporcionar una URL base, clau API i ID de model vàlids.",
+		"openAiExtraBody": {
+			"invalidJson": "El cos addicional ha de contenir JSON vàlid.",
+			"objectRequired": "El cos addicional ha de ser un objecte JSON.",
+			"reservedKeys": "El cos addicional no pot sobreescriure els camps gestionats per Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Format ARN no vàlid. Si us plau, comproveu els requisits del format.",
 			"regionMismatch": "Avís: La regió del vostre ARN ({{arnRegion}}) no coincideix amb la regió seleccionada ({{region}}). Això pot causar problemes d'accés. El proveïdor utilitzarà la regió de l'ARN."
diff --git a/webview-ui/src/i18n/locales/de/settings.json b/webview-ui/src/i18n/locales/de/settings.json
index b895717422..f56984bc73 100644
--- a/webview-ui/src/i18n/locales/de/settings.json
+++ b/webview-ui/src/i18n/locales/de/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Header-Name",
 		"headerValue": "Header-Wert",
 		"noCustomHeaders": "Keine benutzerdefinierten Headers definiert. Klicke auf die + Schaltfläche, um einen hinzuzufügen.",
+		"extraBody": "Zusätzlicher Body",
+		"extraBodyDescription": "Optionales JSON-Objekt, das mit API-Anfrage-Bodys zusammengeführt wird. Von Zoo Code verwaltete Felder wie model, messages, tools und stream können nicht überschrieben werden. Füge keine Geheimnisse ein.",
 		"unboundApiKey": "Unbound API-Schlüssel",
 		"getUnboundApiKey": "Unbound API-Schlüssel erhalten",
 		"requestyApiKey": "Requesty API-Schlüssel",
@@ -1036,6 +1038,11 @@
 		"modelId": "Du musst eine gültige Modell-ID angeben.",
 		"modelSelector": "Du musst einen gültigen Modellselektor angeben.",
 		"openAi": "Du musst eine gültige Basis-URL, einen API-Schlüssel und eine Modell-ID angeben.",
+		"openAiExtraBody": {
+			"invalidJson": "Der zusätzliche Body muss gültiges JSON enthalten.",
+			"objectRequired": "Der zusätzliche Body muss ein JSON-Objekt sein.",
+			"reservedKeys": "Der zusätzliche Body kann von Zoo Code verwaltete Felder nicht überschreiben: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Ungültiges ARN-Format. Bitte überprüfe die Formatanforderungen.",
 			"regionMismatch": "Warnung: Die Region in deiner ARN ({{arnRegion}}) stimmt nicht mit deiner ausgewählten Region ({{region}}) überein. Dies kann zu Zugriffsproblemen führen. Der Anbieter wird die Region aus der ARN verwenden."
diff --git a/webview-ui/src/i18n/locales/en/settings.json b/webview-ui/src/i18n/locales/en/settings.json
index eaa37b7034..77f8a4f86d 100644
--- a/webview-ui/src/i18n/locales/en/settings.json
+++ b/webview-ui/src/i18n/locales/en/settings.json
@@ -540,6 +540,8 @@
 		"headerName": "Header name",
 		"headerValue": "Header value",
 		"noCustomHeaders": "No custom headers defined. Click the + button to add one.",
+		"extraBody": "Extra Body",
+		"extraBodyDescription": "Optional JSON object merged into API request bodies. Zoo Code-managed fields such as model, messages, tools, and stream cannot be overridden. Do not include secrets.",
 		"unboundApiKey": "Unbound API Key",
 		"getUnboundApiKey": "Get Unbound API Key",
 		"requestyApiKey": "Requesty API Key",
@@ -1116,6 +1118,11 @@
 		"modelId": "You must provide a valid model ID.",
 		"modelSelector": "You must provide a valid model selector.",
 		"openAi": "You must provide a valid base URL, API key, and model ID.",
+		"openAiExtraBody": {
+			"invalidJson": "Extra Body must contain valid JSON.",
+			"objectRequired": "Extra Body must be a JSON object.",
+			"reservedKeys": "Extra Body cannot override Zoo Code-managed fields: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Invalid ARN format. Please check the format requirements.",
 			"regionMismatch": "Warning: The region in your ARN ({{arnRegion}}) does not match your selected region ({{region}}). This may cause access issues. The provider will use the region from the ARN."
diff --git a/webview-ui/src/i18n/locales/es/settings.json b/webview-ui/src/i18n/locales/es/settings.json
index abb8a60609..e730483fa0 100644
--- a/webview-ui/src/i18n/locales/es/settings.json
+++ b/webview-ui/src/i18n/locales/es/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nombre del encabezado",
 		"headerValue": "Valor del encabezado",
 		"noCustomHeaders": "No hay encabezados personalizados definidos. Haga clic en el botón + para añadir uno.",
+		"extraBody": "Cuerpo adicional",
+		"extraBodyDescription": "Objeto JSON opcional que se combina con los cuerpos de las solicitudes de API. Los campos gestionados por Zoo Code, como model, messages, tools y stream, no se pueden sobrescribir. No incluya secretos.",
 		"unboundApiKey": "Clave API de Unbound",
 		"getUnboundApiKey": "Obtener clave API de Unbound",
 		"requestyApiKey": "Clave API de Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "Debe proporcionar un ID de modelo válido.",
 		"modelSelector": "Debe proporcionar un selector de modelo válido.",
 		"openAi": "Debe proporcionar una URL base, clave API y ID de modelo válidos.",
+		"openAiExtraBody": {
+			"invalidJson": "El cuerpo adicional debe contener JSON válido.",
+			"objectRequired": "El cuerpo adicional debe ser un objeto JSON.",
+			"reservedKeys": "El cuerpo adicional no puede sobrescribir los campos gestionados por Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Formato de ARN no válido. Por favor, verifique los requisitos de formato.",
 			"regionMismatch": "Advertencia: La región en su ARN ({{arnRegion}}) no coincide con su región seleccionada ({{region}}). Esto puede causar problemas de acceso. El proveedor usará la región del ARN."
diff --git a/webview-ui/src/i18n/locales/fr/settings.json b/webview-ui/src/i18n/locales/fr/settings.json
index 272f21a6ee..78770da21d 100644
--- a/webview-ui/src/i18n/locales/fr/settings.json
+++ b/webview-ui/src/i18n/locales/fr/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nom de l'en-tête",
 		"headerValue": "Valeur de l'en-tête",
 		"noCustomHeaders": "Aucun en-tête personnalisé défini. Cliquez sur le bouton + pour en ajouter un.",
+		"extraBody": "Corps supplémentaire",
+		"extraBodyDescription": "Objet JSON facultatif fusionné avec le corps des requêtes API. Les champs gérés par Zoo Code, tels que model, messages, tools et stream, ne peuvent pas être remplacés. N'incluez pas de secrets.",
 		"unboundApiKey": "Clé API Unbound",
 		"getUnboundApiKey": "Obtenir la clé API Unbound",
 		"requestyApiKey": "Clé API Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "Vous devez fournir un ID de modèle valide.",
 		"modelSelector": "Vous devez fournir un sélecteur de modèle valide.",
 		"openAi": "Vous devez fournir une URL de base, une clé API et un ID de modèle valides.",
+		"openAiExtraBody": {
+			"invalidJson": "Le corps supplémentaire doit contenir un JSON valide.",
+			"objectRequired": "Le corps supplémentaire doit être un objet JSON.",
+			"reservedKeys": "Le corps supplémentaire ne peut pas remplacer les champs gérés par Zoo Code : {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Format ARN invalide. Veuillez vérifier les exigences de format.",
 			"regionMismatch": "Attention : La région dans votre ARN ({{arnRegion}}) ne correspond pas à votre région sélectionnée ({{region}}). Cela peut causer des problèmes d'accès. Le fournisseur utilisera la région de l'ARN."
diff --git a/webview-ui/src/i18n/locales/hi/settings.json b/webview-ui/src/i18n/locales/hi/settings.json
index 0a4152b17a..413d3515bc 100644
--- a/webview-ui/src/i18n/locales/hi/settings.json
+++ b/webview-ui/src/i18n/locales/hi/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "हेडर नाम",
 		"headerValue": "हेडर मूल्य",
 		"noCustomHeaders": "कोई कस्टम हेडर परिभाषित नहीं है। एक जोड़ने के लिए + बटन पर क्लिक करें।",
+		"extraBody": "अतिरिक्त बॉडी",
+		"extraBodyDescription": "वैकल्पिक JSON ऑब्जेक्ट जिसे API अनुरोध बॉडी में मर्ज किया जाता है। Zoo Code द्वारा प्रबंधित फ़ील्ड, जैसे model, messages, tools और stream, ओवरराइड नहीं किए जा सकते। गोपनीय जानकारी शामिल न करें।",
 		"unboundApiKey": "Unbound API कुंजी",
 		"getUnboundApiKey": "Unbound API कुंजी प्राप्त करें",
 		"requestyApiKey": "Requesty API कुंजी",
@@ -1036,6 +1038,11 @@
 		"modelId": "आपको एक मान्य मॉडल ID प्रदान करनी होगी।",
 		"modelSelector": "आपको एक मान्य मॉडल चयनकर्ता प्रदान करना होगा।",
 		"openAi": "आपको एक मान्य बेस URL, API कुंजी और मॉडल ID प्रदान करनी होगी।",
+		"openAiExtraBody": {
+			"invalidJson": "अतिरिक्त बॉडी में मान्य JSON होना चाहिए।",
+			"objectRequired": "अतिरिक्त बॉडी एक JSON ऑब्जेक्ट होनी चाहिए।",
+			"reservedKeys": "अतिरिक्त बॉडी Zoo Code द्वारा प्रबंधित फ़ील्ड को ओवरराइड नहीं कर सकती: {{keys}}।"
+		},
 		"arn": {
 			"invalidFormat": "अमान्य ARN प्रारूप। कृपया प्रारूप आवश्यकताएं जांचें।",
 			"regionMismatch": "चेतावनी: आपके ARN में क्षेत्र ({{arnRegion}}) आपके चयनित क्षेत्र ({{region}}) से मेल नहीं खाता। इससे पहुंच संबंधी समस्याएं हो सकती हैं। प्रदाता ARN से क्षेत्र का उपयोग करेगा।"
diff --git a/webview-ui/src/i18n/locales/id/settings.json b/webview-ui/src/i18n/locales/id/settings.json
index b8abe9ab25..9b9928da64 100644
--- a/webview-ui/src/i18n/locales/id/settings.json
+++ b/webview-ui/src/i18n/locales/id/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nama header",
 		"headerValue": "Nilai header",
 		"noCustomHeaders": "Tidak ada header kustom yang didefinisikan. Klik tombol + untuk menambahkan satu.",
+		"extraBody": "Body Tambahan",
+		"extraBodyDescription": "Objek JSON opsional yang digabungkan ke body permintaan API. Field yang dikelola Zoo Code seperti model, messages, tools, dan stream tidak dapat ditimpa. Jangan sertakan rahasia.",
 		"unboundApiKey": "Unbound API Key",
 		"getUnboundApiKey": "Dapatkan Unbound API Key",
 		"requestyApiKey": "Requesty API Key",
@@ -1036,6 +1038,11 @@
 		"modelId": "Kamu harus menyediakan model ID yang valid.",
 		"modelSelector": "Kamu harus menyediakan model selector yang valid.",
 		"openAi": "Kamu harus menyediakan base URL, API key, dan model ID yang valid.",
+		"openAiExtraBody": {
+			"invalidJson": "Body Tambahan harus berisi JSON yang valid.",
+			"objectRequired": "Body Tambahan harus berupa objek JSON.",
+			"reservedKeys": "Body Tambahan tidak dapat menimpa field yang dikelola Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Format ARN tidak valid. Silakan periksa persyaratan format.",
 			"regionMismatch": "Peringatan: Region di ARN kamu ({{arnRegion}}) tidak cocok dengan region yang kamu pilih ({{region}}). Ini dapat menyebabkan masalah akses. Provider akan menggunakan region dari ARN."
diff --git a/webview-ui/src/i18n/locales/it/settings.json b/webview-ui/src/i18n/locales/it/settings.json
index e49ede9cec..8a43ec3d35 100644
--- a/webview-ui/src/i18n/locales/it/settings.json
+++ b/webview-ui/src/i18n/locales/it/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nome intestazione",
 		"headerValue": "Valore intestazione",
 		"noCustomHeaders": "Nessuna intestazione personalizzata definita. Fai clic sul pulsante + per aggiungerne una.",
+		"extraBody": "Corpo aggiuntivo",
+		"extraBodyDescription": "Oggetto JSON facoltativo unito ai corpi delle richieste API. I campi gestiti da Zoo Code, come model, messages, tools e stream, non possono essere sovrascritti. Non includere segreti.",
 		"unboundApiKey": "Chiave API Unbound",
 		"getUnboundApiKey": "Ottieni chiave API Unbound",
 		"requestyApiKey": "Chiave API Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "È necessario fornire un ID modello valido.",
 		"modelSelector": "È necessario fornire un selettore di modello valido.",
 		"openAi": "È necessario fornire un URL base, una chiave API e un ID modello validi.",
+		"openAiExtraBody": {
+			"invalidJson": "Il corpo aggiuntivo deve contenere JSON valido.",
+			"objectRequired": "Il corpo aggiuntivo deve essere un oggetto JSON.",
+			"reservedKeys": "Il corpo aggiuntivo non può sovrascrivere i campi gestiti da Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Formato ARN non valido. Verificare i requisiti del formato.",
 			"regionMismatch": "Attenzione: La regione nel tuo ARN ({{arnRegion}}) non corrisponde alla regione selezionata ({{region}}). Questo potrebbe causare problemi di accesso. Il provider utilizzerà la regione dall'ARN."
diff --git a/webview-ui/src/i18n/locales/ja/settings.json b/webview-ui/src/i18n/locales/ja/settings.json
index d58c86c95d..b2cfbe977e 100644
--- a/webview-ui/src/i18n/locales/ja/settings.json
+++ b/webview-ui/src/i18n/locales/ja/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "ヘッダー名",
 		"headerValue": "ヘッダー値",
 		"noCustomHeaders": "カスタムヘッダーが定義されていません。+ ボタンをクリックして追加してください。",
+		"extraBody": "追加ボディ",
+		"extraBodyDescription": "APIリクエストボディにマージされる任意のJSONオブジェクトです。model、messages、tools、streamなど、Zoo Codeが管理するフィールドは上書きできません。機密情報を含めないでください。",
 		"unboundApiKey": "Unbound API キー",
 		"getUnboundApiKey": "Unbound APIキーを取得",
 		"requestyApiKey": "Requesty APIキー",
@@ -1036,6 +1038,11 @@
 		"modelId": "有効なモデルIDを入力してください。",
 		"modelSelector": "有効なモデルセレクターを入力してください。",
 		"openAi": "有効なベースURL、APIキー、モデルIDを入力してください。",
+		"openAiExtraBody": {
+			"invalidJson": "追加ボディには有効なJSONを指定してください。",
+			"objectRequired": "追加ボディはJSONオブジェクトである必要があります。",
+			"reservedKeys": "追加ボディではZoo Codeが管理するフィールドを上書きできません：{{keys}}。"
+		},
 		"arn": {
 			"invalidFormat": "ARNの形式が無効です。フォーマット要件を確認してください。",
 			"regionMismatch": "警告：ARN内のリージョン（{{arnRegion}}）が選択したリージョン（{{region}}）と一致しません。これによりアクセスの問題が発生する可能性があります。プロバイダーはARNのリージョンを使用します。"
diff --git a/webview-ui/src/i18n/locales/ko/settings.json b/webview-ui/src/i18n/locales/ko/settings.json
index 68ce8b2523..1ff9addeb4 100644
--- a/webview-ui/src/i18n/locales/ko/settings.json
+++ b/webview-ui/src/i18n/locales/ko/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "헤더 이름",
 		"headerValue": "헤더 값",
 		"noCustomHeaders": "정의된 사용자 정의 헤더가 없습니다. + 버튼을 클릭하여 추가하세요.",
+		"extraBody": "추가 본문",
+		"extraBodyDescription": "API 요청 본문에 병합되는 선택적 JSON 객체입니다. model, messages, tools, stream 등 Zoo Code에서 관리하는 필드는 재정의할 수 없습니다. 비밀 정보를 포함하지 마세요.",
 		"unboundApiKey": "Unbound API 키",
 		"getUnboundApiKey": "Unbound API 키 받기",
 		"requestyApiKey": "Requesty API 키",
@@ -1036,6 +1038,11 @@
 		"modelId": "유효한 모델 ID를 입력해야 합니다.",
 		"modelSelector": "유효한 모델 선택기를 입력해야 합니다.",
 		"openAi": "유효한 기본 URL, API 키, 모델 ID를 입력해야 합니다.",
+		"openAiExtraBody": {
+			"invalidJson": "추가 본문에는 유효한 JSON이 있어야 합니다.",
+			"objectRequired": "추가 본문은 JSON 객체여야 합니다.",
+			"reservedKeys": "추가 본문은 Zoo Code에서 관리하는 필드를 재정의할 수 없습니다: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "ARN 형식이 잘못되었습니다. 형식 요구사항을 확인하세요.",
 			"regionMismatch": "경고: ARN의 리전({{arnRegion}})이 선택한 리전({{region}})과 일치하지 않습니다. 접근 문제가 발생할 수 있습니다. 제공자는 ARN의 리전을 사용합니다."
diff --git a/webview-ui/src/i18n/locales/nl/settings.json b/webview-ui/src/i18n/locales/nl/settings.json
index 8d90d7747e..4361d091a1 100644
--- a/webview-ui/src/i18n/locales/nl/settings.json
+++ b/webview-ui/src/i18n/locales/nl/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Headernaam",
 		"headerValue": "Headerwaarde",
 		"noCustomHeaders": "Geen aangepaste headers gedefinieerd. Klik op de + knop om er een toe te voegen.",
+		"extraBody": "Extra body",
+		"extraBodyDescription": "Optioneel JSON-object dat wordt samengevoegd met API-aanvraagbody's. Door Zoo Code beheerde velden zoals model, messages, tools en stream kunnen niet worden overschreven. Voeg geen geheimen toe.",
 		"unboundApiKey": "Unbound API sleutel",
 		"getUnboundApiKey": "Unbound API-sleutel ophalen",
 		"requestyApiKey": "Requesty API-sleutel",
@@ -1036,6 +1038,11 @@
 		"modelId": "Je moet een geldig model-ID opgeven.",
 		"modelSelector": "Je moet een geldige modelselector opgeven.",
 		"openAi": "Je moet een geldige basis-URL, API-sleutel en model-ID opgeven.",
+		"openAiExtraBody": {
+			"invalidJson": "De extra body moet geldige JSON bevatten.",
+			"objectRequired": "De extra body moet een JSON-object zijn.",
+			"reservedKeys": "De extra body kan door Zoo Code beheerde velden niet overschrijven: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Ongeldig ARN-formaat. Controleer de formaatvereisten.",
 			"regionMismatch": "Waarschuwing: De regio in je ARN ({{arnRegion}}) komt niet overeen met je geselecteerde regio ({{region}}). Dit kan toegangsfouten veroorzaken. De provider gebruikt de regio uit de ARN."
diff --git a/webview-ui/src/i18n/locales/pl/settings.json b/webview-ui/src/i18n/locales/pl/settings.json
index ffc1cdf1a4..277bcaa470 100644
--- a/webview-ui/src/i18n/locales/pl/settings.json
+++ b/webview-ui/src/i18n/locales/pl/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nazwa nagłówka",
 		"headerValue": "Wartość nagłówka",
 		"noCustomHeaders": "Brak zdefiniowanych niestandardowych nagłówków. Kliknij przycisk +, aby dodać.",
+		"extraBody": "Dodatkowa treść",
+		"extraBodyDescription": "Opcjonalny obiekt JSON scalany z treścią żądań API. Pola zarządzane przez Zoo Code, takie jak model, messages, tools i stream, nie mogą zostać nadpisane. Nie umieszczaj tu sekretów.",
 		"unboundApiKey": "Klucz API Unbound",
 		"getUnboundApiKey": "Uzyskaj klucz API Unbound",
 		"requestyApiKey": "Klucz API Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "Musisz podać prawidłowe ID modelu.",
 		"modelSelector": "Musisz podać prawidłowy selektor modelu.",
 		"openAi": "Musisz podać prawidłowy bazowy URL, klucz API i ID modelu.",
+		"openAiExtraBody": {
+			"invalidJson": "Dodatkowa treść musi zawierać prawidłowy kod JSON.",
+			"objectRequired": "Dodatkowa treść musi być obiektem JSON.",
+			"reservedKeys": "Dodatkowa treść nie może nadpisywać pól zarządzanych przez Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Nieprawidłowy format ARN. Sprawdź wymagania dotyczące formatu.",
 			"regionMismatch": "Ostrzeżenie: Region w Twoim ARN ({{arnRegion}}) nie zgadza się z wybranym regionem ({{region}}). Może to powodować problemy z dostępem. Dostawca użyje regionu z ARN."
diff --git a/webview-ui/src/i18n/locales/pt-BR/settings.json b/webview-ui/src/i18n/locales/pt-BR/settings.json
index cf92b76ac7..8ce67bcd48 100644
--- a/webview-ui/src/i18n/locales/pt-BR/settings.json
+++ b/webview-ui/src/i18n/locales/pt-BR/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Nome do cabeçalho",
 		"headerValue": "Valor do cabeçalho",
 		"noCustomHeaders": "Nenhum cabeçalho personalizado definido. Clique no botão + para adicionar um.",
+		"extraBody": "Corpo adicional",
+		"extraBodyDescription": "Objeto JSON opcional mesclado aos corpos das solicitações de API. Os campos gerenciados pelo Zoo Code, como model, messages, tools e stream, não podem ser sobrescritos. Não inclua segredos.",
 		"unboundApiKey": "Chave de API Unbound",
 		"getUnboundApiKey": "Obter chave de API Unbound",
 		"requestyApiKey": "Chave de API Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "Você deve fornecer um ID de modelo válido.",
 		"modelSelector": "Você deve fornecer um seletor de modelo válido.",
 		"openAi": "Você deve fornecer uma URL base, chave de API e ID de modelo válidos.",
+		"openAiExtraBody": {
+			"invalidJson": "O corpo adicional deve conter um JSON válido.",
+			"objectRequired": "O corpo adicional deve ser um objeto JSON.",
+			"reservedKeys": "O corpo adicional não pode sobrescrever os campos gerenciados pelo Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Formato de ARN inválido. Por favor, verifique os requisitos de formato.",
 			"regionMismatch": "Aviso: A região em seu ARN ({{arnRegion}}) não corresponde à região selecionada ({{region}}). Isso pode causar problemas de acesso. O provedor usará a região do ARN."
diff --git a/webview-ui/src/i18n/locales/ru/settings.json b/webview-ui/src/i18n/locales/ru/settings.json
index 23ff32faa9..0ac516c190 100644
--- a/webview-ui/src/i18n/locales/ru/settings.json
+++ b/webview-ui/src/i18n/locales/ru/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Имя заголовка",
 		"headerValue": "Значение заголовка",
 		"noCustomHeaders": "Пользовательские заголовки не определены. Нажмите кнопку +, чтобы добавить.",
+		"extraBody": "Дополнительное тело",
+		"extraBodyDescription": "Необязательный объект JSON, объединяемый с телами запросов API. Поля, управляемые Zoo Code, такие как model, messages, tools и stream, нельзя переопределить. Не включайте секреты.",
 		"unboundApiKey": "Unbound API-ключ",
 		"getUnboundApiKey": "Получить Unbound API-ключ",
 		"requestyApiKey": "Requesty API-ключ",
@@ -1036,6 +1038,11 @@
 		"modelId": "Вы должны указать действительный ID модели.",
 		"modelSelector": "Вы должны указать действительный селектор модели.",
 		"openAi": "Вы должны указать действительный базовый URL, API-ключ и ID модели.",
+		"openAiExtraBody": {
+			"invalidJson": "Дополнительное тело должно содержать допустимый JSON.",
+			"objectRequired": "Дополнительное тело должно быть объектом JSON.",
+			"reservedKeys": "Дополнительное тело не может переопределять поля, управляемые Zoo Code: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Неверный формат ARN. Проверьте требования к формату.",
 			"regionMismatch": "Внимание: регион в вашем ARN ({{arnRegion}}) не совпадает с выбранным регионом ({{region}}). Это может вызвать проблемы с доступом. Провайдер будет использовать регион из ARN."
diff --git a/webview-ui/src/i18n/locales/tr/settings.json b/webview-ui/src/i18n/locales/tr/settings.json
index f674e116d2..5d3a5cb89a 100644
--- a/webview-ui/src/i18n/locales/tr/settings.json
+++ b/webview-ui/src/i18n/locales/tr/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Başlık adı",
 		"headerValue": "Başlık değeri",
 		"noCustomHeaders": "Tanımlanmış özel başlık yok. Eklemek için + düğmesine tıklayın.",
+		"extraBody": "Ek Gövde",
+		"extraBodyDescription": "API istek gövdeleriyle birleştirilen isteğe bağlı JSON nesnesi. model, messages, tools ve stream gibi Zoo Code tarafından yönetilen alanlar geçersiz kılınamaz. Gizli bilgiler eklemeyin.",
 		"unboundApiKey": "Unbound API Anahtarı",
 		"getUnboundApiKey": "Unbound API Anahtarı Al",
 		"requestyApiKey": "Requesty API Anahtarı",
@@ -1036,6 +1038,11 @@
 		"modelId": "Geçerli bir model kimliği sağlamalısınız.",
 		"modelSelector": "Geçerli bir model seçici sağlamalısınız.",
 		"openAi": "Geçerli bir temel URL, API anahtarı ve model kimliği sağlamalısınız.",
+		"openAiExtraBody": {
+			"invalidJson": "Ek Gövde geçerli JSON içermelidir.",
+			"objectRequired": "Ek Gövde bir JSON nesnesi olmalıdır.",
+			"reservedKeys": "Ek Gövde, Zoo Code tarafından yönetilen alanları geçersiz kılamaz: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Geçersiz ARN formatı. Lütfen format gereksinimlerini kontrol edin.",
 			"regionMismatch": "Uyarı: ARN'nizdeki bölge ({{arnRegion}}) seçtiğiniz bölge ({{region}}) ile eşleşmiyor. Bu erişim sorunlarına neden olabilir. Sağlayıcı, ARN'deki bölgeyi kullanacak."
diff --git a/webview-ui/src/i18n/locales/vi/settings.json b/webview-ui/src/i18n/locales/vi/settings.json
index 4b908ca658..adb1be64e3 100644
--- a/webview-ui/src/i18n/locales/vi/settings.json
+++ b/webview-ui/src/i18n/locales/vi/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "Tên tiêu đề",
 		"headerValue": "Giá trị tiêu đề",
 		"noCustomHeaders": "Chưa có tiêu đề tùy chỉnh nào được định nghĩa. Nhấp vào nút + để thêm.",
+		"extraBody": "Nội dung bổ sung",
+		"extraBodyDescription": "Đối tượng JSON tùy chọn được hợp nhất vào phần thân yêu cầu API. Không thể ghi đè các trường do Zoo Code quản lý như model, messages, tools và stream. Không bao gồm thông tin bí mật.",
 		"unboundApiKey": "Khóa API Unbound",
 		"getUnboundApiKey": "Lấy khóa API Unbound",
 		"requestyApiKey": "Khóa API Requesty",
@@ -1036,6 +1038,11 @@
 		"modelId": "Bạn phải cung cấp ID mô hình hợp lệ.",
 		"modelSelector": "Bạn phải cung cấp bộ chọn mô hình hợp lệ.",
 		"openAi": "Bạn phải cung cấp URL cơ sở, khóa API và ID mô hình hợp lệ.",
+		"openAiExtraBody": {
+			"invalidJson": "Nội dung bổ sung phải chứa JSON hợp lệ.",
+			"objectRequired": "Nội dung bổ sung phải là một đối tượng JSON.",
+			"reservedKeys": "Nội dung bổ sung không thể ghi đè các trường do Zoo Code quản lý: {{keys}}."
+		},
 		"arn": {
 			"invalidFormat": "Định dạng ARN không hợp lệ. Vui lòng kiểm tra yêu cầu về định dạng.",
 			"regionMismatch": "Cảnh báo: Vùng trong ARN của bạn ({{arnRegion}}) không khớp với vùng bạn đã chọn ({{region}}). Điều này có thể gây ra vấn đề truy cập. Nhà cung cấp sẽ sử dụng vùng từ ARN."
diff --git a/webview-ui/src/i18n/locales/zh-CN/settings.json b/webview-ui/src/i18n/locales/zh-CN/settings.json
index d79edca302..916f629efe 100644
--- a/webview-ui/src/i18n/locales/zh-CN/settings.json
+++ b/webview-ui/src/i18n/locales/zh-CN/settings.json
@@ -460,6 +460,8 @@
 		"headerName": "标头名称",
 		"headerValue": "标头值",
 		"noCustomHeaders": "暂无自定义标头。点击 + 按钮添加。",
+		"extraBody": "附加请求体",
+		"extraBodyDescription": "合并到 API 请求体中的可选 JSON 对象。无法覆盖由 Zoo Code 管理的字段，例如 model、messages、tools 和 stream。请勿包含密钥。",
 		"unboundApiKey": "Unbound API 密钥",
 		"getUnboundApiKey": "获取 Unbound API 密钥",
 		"requestyApiKey": "Requesty API 密钥",
@@ -1036,6 +1038,11 @@
 		"modelId": "您必须提供有效的模型 ID。",
 		"modelSelector": "您必须提供有效的模型选择器。",
 		"openAi": "您必须提供有效的基础 URL、API 密钥和模型 ID。",
+		"openAiExtraBody": {
+			"invalidJson": "附加请求体必须包含有效的 JSON。",
+			"objectRequired": "附加请求体必须是 JSON 对象。",
+			"reservedKeys": "附加请求体无法覆盖由 Zoo Code 管理的字段：{{keys}}。"
+		},
 		"arn": {
 			"invalidFormat": "ARN 格式无效。请检查格式要求。",
 			"regionMismatch": "警告：您的 ARN 中的区域 ({{arnRegion}}) 与您选择的区域 ({{region}}) 不匹配。这可能会导致访问问题。提供程序将使用 ARN 中的区域。"
diff --git a/webview-ui/src/i18n/locales/zh-TW/settings.json b/webview-ui/src/i18n/locales/zh-TW/settings.json
index 250cc2111b..d1f9258dcf 100644
--- a/webview-ui/src/i18n/locales/zh-TW/settings.json
+++ b/webview-ui/src/i18n/locales/zh-TW/settings.json
@@ -487,6 +487,8 @@
 		"headerName": "標頭名稱",
 		"headerValue": "標頭值",
 		"noCustomHeaders": "尚未定義自訂標頭。點選 + 按鈕以新增。",
+		"extraBody": "附加請求本文",
+		"extraBodyDescription": "合併到 API 請求本文中的選用 JSON 物件。無法覆寫由 Zoo Code 管理的欄位，例如 model、messages、tools 和 stream。請勿包含秘密資訊。",
 		"unboundApiKey": "Unbound API 金鑰",
 		"getUnboundApiKey": "取得 Unbound API 金鑰",
 		"requestyApiKey": "Requesty API 金鑰",
@@ -1063,6 +1065,11 @@
 		"modelId": "請提供有效的模型 ID。",
 		"modelSelector": "請提供有效的模型選擇器。",
 		"openAi": "請提供有效的基礎 URL、API 金鑰和模型 ID。",
+		"openAiExtraBody": {
+			"invalidJson": "附加請求本文必須包含有效的 JSON。",
+			"objectRequired": "附加請求本文必須是 JSON 物件。",
+			"reservedKeys": "附加請求本文無法覆寫由 Zoo Code 管理的欄位：{{keys}}。"
+		},
 		"arn": {
 			"invalidFormat": "ARN 格式無效，請檢查格式要求。",
 			"regionMismatch": "警告：您 ARN 中的區域 ({{arnRegion}}) 與您選擇的區域 ({{region}}) 不符，可能導致存取問題。系統將使用 ARN 中指定的區域。"
diff --git a/webview-ui/src/utils/__tests__/validate.spec.ts b/webview-ui/src/utils/__tests__/validate.spec.ts
index 6535e3ba61..175ca53ece 100644
--- a/webview-ui/src/utils/__tests__/validate.spec.ts
+++ b/webview-ui/src/utils/__tests__/validate.spec.ts
@@ -225,6 +225,38 @@ describe("Model Validation Functions", () => {
 			)
 			expect(result).toBeUndefined() // Should exclude model-specific org errors
 		})
+
+		it("accepts a valid OpenAI-compatible Extra Body object", () => {
+			const config: ProviderSettings = {
+				apiProvider: providerIdentifiers.openai,
+				openAiBaseUrl: "https://api.sailresearch.com/v1",
+				openAiApiKey: "valid-key",
+				openAiModelId: "zai-org/GLM-5.2-FP8",
+				openAiExtraBody: JSON.stringify({ metadata: { completion_window: "balanced" } }),
+			}
+
+			expect(
+				validateApiConfigurationExcludingModelErrors(config, mockRouterModels, allowAllOrganization),
+			).toBeUndefined()
+		})
+
+		it.each([
+			["not json", "settings:validation.openAiExtraBody.invalidJson"],
+			["[]", "settings:validation.openAiExtraBody.objectRequired"],
+			[JSON.stringify({ model: "override" }), "settings:validation.openAiExtraBody.reservedKeys keys=model"],
+		])("rejects invalid OpenAI-compatible Extra Body input", (openAiExtraBody, expectedError) => {
+			const config: ProviderSettings = {
+				apiProvider: providerIdentifiers.openai,
+				openAiBaseUrl: "https://api.sailresearch.com/v1",
+				openAiApiKey: "valid-key",
+				openAiModelId: "zai-org/GLM-5.2-FP8",
+				openAiExtraBody,
+			}
+
+			expect(validateApiConfigurationExcludingModelErrors(config, mockRouterModels, allowAllOrganization)).toBe(
+				expectedError,
+			)
+		})
 	})
 
 	describe("Opencode Go validation", () => {
diff --git a/webview-ui/src/utils/validate.ts b/webview-ui/src/utils/validate.ts
index 4174e8f821..7deb7c56bd 100644
--- a/webview-ui/src/utils/validate.ts
+++ b/webview-ui/src/utils/validate.ts
@@ -6,6 +6,7 @@ import {
 	type RouterModels,
 	getModelId,
 	isDynamicProvider,
+	parseOpenAiExtraBody,
 	providerIdentifiers,
 } from "@roo-code/types"
 
@@ -311,6 +312,19 @@ export function validateApiConfigurationExcludingModelErrors(
 		}
 	}
 
+	if (apiConfiguration.apiProvider === providerIdentifiers.openai) {
+		const extraBodyResult = parseOpenAiExtraBody(apiConfiguration.openAiExtraBody)
+		if (!extraBodyResult.success) {
+			if (extraBodyResult.reason === "reservedKeys") {
+				return i18next.t("settings:validation.openAiExtraBody.reservedKeys", {
+					keys: extraBodyResult.reservedKeys?.join(", ") ?? "",
+				})
+			}
+
+			return i18next.t(`settings:validation.openAiExtraBody.${extraBodyResult.reason}`)
+		}
+	}
+
 	const organizationAllowListError = validateProviderAgainstOrganizationSettings(
 		apiConfiguration,
 		organizationAllowList,