diff --git a/src/client/consts.ts b/src/client/consts.ts
index 0a4ade7..91d40db 100644
--- a/src/client/consts.ts
+++ b/src/client/consts.ts
@@ -6,7 +6,6 @@ import type {
 } from './types';
 import { EXTERNAL_URLS } from '../consts';
 
-export const OFFICIAL_DEEPSEEK_API_HOST = 'api.deepseek.com';
 export const MAX_DIAGNOSTIC_FIELD_LENGTH = 300;
 
 export const API_PROVIDER_HTTP_ERROR_LINKS: Readonly<
diff --git a/src/client/error/index.ts b/src/client/error/index.ts
index de3f428..ac34bc3 100644
--- a/src/client/error/index.ts
+++ b/src/client/error/index.ts
@@ -1,10 +1,7 @@
+import { isOfficialDeepSeekBaseUrl } from '../../endpoint';
 import { t } from '../../i18n';
 import { safeStringify } from '../../json';
-import {
-	API_PROVIDER_HTTP_ERROR_LINKS,
-	MAX_DIAGNOSTIC_FIELD_LENGTH,
-	OFFICIAL_DEEPSEEK_API_HOST,
-} from '../consts';
+import { API_PROVIDER_HTTP_ERROR_LINKS, MAX_DIAGNOSTIC_FIELD_LENGTH } from '../consts';
 import { getNetworkErrorCauseInfo, getNetworkErrorCode, getNetworkErrorMessage } from './network';
 import type {
 	ApiProviderId,
@@ -322,12 +319,7 @@ function escapeBoldText(value: string): string {
 }
 
 function identifyApiProvider(baseUrl: string): ApiProviderId | undefined {
-	try {
-		const hostname = new URL(baseUrl).hostname.toLowerCase();
-		return hostname === OFFICIAL_DEEPSEEK_API_HOST ? 'deepseek' : undefined;
-	} catch {
-		return undefined;
-	}
+	return isOfficialDeepSeekBaseUrl(baseUrl) ? 'deepseek' : undefined;
 }
 
 function getHttpErrorLinkStatusKey(status: number): HttpErrorLinkStatusKey | undefined {
diff --git a/src/endpoint.ts b/src/endpoint.ts
new file mode 100644
index 0000000..019ce07
--- /dev/null
+++ b/src/endpoint.ts
@@ -0,0 +1,13 @@
+export const OFFICIAL_DEEPSEEK_API_HOST = 'api.deepseek.com';
+
+export function isOfficialDeepSeekBaseUrl(baseUrl: string): boolean {
+	try {
+		return new URL(baseUrl).hostname.toLowerCase() === OFFICIAL_DEEPSEEK_API_HOST;
+	} catch {
+		return false;
+	}
+}
+
+export function normalizeBaseUrl(baseUrl: string): string {
+	return baseUrl.trim().replace(/\/+$/u, '');
+}
diff --git a/src/provider/pricing/currency.ts b/src/provider/pricing/currency.ts
index 604f2ef..2211bb9 100644
--- a/src/provider/pricing/currency.ts
+++ b/src/provider/pricing/currency.ts
@@ -1,7 +1,7 @@
 import vscode from 'vscode';
 import { AuthManager } from '../../auth';
-import { OFFICIAL_DEEPSEEK_API_HOST } from '../../client/consts';
 import { getBaseUrl } from '../../config';
+import { isOfficialDeepSeekBaseUrl, normalizeBaseUrl } from '../../endpoint';
 import { logger } from '../../logger';
 import type { PricingCurrency } from '../../types';
 
@@ -133,18 +133,6 @@ export class BalanceCurrencyResolver {
 	}
 }
 
-export function isOfficialDeepSeekBaseUrl(baseUrl: string): boolean {
-	try {
-		return new URL(baseUrl).hostname.toLowerCase() === OFFICIAL_DEEPSEEK_API_HOST;
-	} catch {
-		return false;
-	}
-}
-
-export function normalizeBaseUrl(baseUrl: string): string {
-	return baseUrl.trim().replace(/\/+$/u, '');
-}
-
 function getLocaleFallbackCurrency(): PricingCurrency {
 	return vscode.env.language.toLowerCase().startsWith('zh') ? 'CNY' : 'USD';
 }
diff --git a/src/provider/request.ts b/src/provider/request.ts
index b9dcf90..c143325 100644
--- a/src/provider/request.ts
+++ b/src/provider/request.ts
@@ -3,6 +3,7 @@ import { AuthManager } from '../auth';
 import { DeepSeekClient } from '../client';
 import { getApiModelId, getBaseUrl, getMaxTokens } from '../config';
 import { MODELS } from '../consts';
+import { isOfficialDeepSeekBaseUrl } from '../endpoint';
 import { t } from '../i18n';
 import type { DeepSeekRequest } from '../types';
 import { convertMessages, countMessageChars } from './convert';
@@ -60,7 +61,8 @@ export async function prepareChatRequest({
 		throw new Error(t('auth.notConfigured'));
 	}
 
-	const client = new DeepSeekClient(getBaseUrl(), apiKey);
+	const baseUrl = getBaseUrl();
+	const client = new DeepSeekClient(baseUrl, apiKey);
 	const modelDef = MODELS.find((m) => m.id === modelInfo.id);
 	const isThinkingModel = modelDef?.capabilities.thinking ?? false;
 	const maxTokens = getMaxTokens();
@@ -86,7 +88,11 @@ export async function prepareChatRequest({
 	const configuredThinkingEffort = getConfiguredThinkingEffort(
 		options as ModelConfigurationOptions,
 	);
-	const thinkingEffort = shouldForceThinkingNone(requestKind) ? 'none' : configuredThinkingEffort;
+	// Only force helper requests into disabled thinking on the official API.
+	// Custom endpoints keep their configured effort to preserve pre-#137 request shape.
+	const forceNoneThinking =
+		shouldForceThinkingNone(requestKind) && isOfficialDeepSeekBaseUrl(baseUrl);
+	const thinkingEffort = forceNoneThinking ? 'none' : configuredThinkingEffort;
 	const request: DeepSeekRequest = {
 		...baseRequest,
 		...(isThinkingModel