From aa178b766f90209fdd5c65d91c151c6be64ea455 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maple=EF=BC=81?= <mapleee723@gmail.com>
Date: Sat, 23 May 2026 03:36:21 +0800
Subject: [PATCH 1/2] Add Anthropic Compatible provider for local LLM endpoints

Support local runtimes (oMLX, LM Studio) and cloud services (Ollama Cloud)
that implement the Anthropic Messages API format. Uses Bearer auth instead
of x-api-key to align with openai-compatible and work across services.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 apps/extension/public/options.html            |  19 +++-
 .../background/providers/anthropic.test.ts    | 103 +++++++++++++++++-
 .../src/background/providers/anthropic.ts     |  20 +++-
 .../src/background/providers/index.test.ts    |   2 +-
 .../src/background/providers/index.ts         |   3 +-
 .../src/background/serviceWorker.test.ts      |  73 +++++++++++--
 .../extension/src/background/serviceWorker.ts |   5 +-
 .../src/content/orchestrator.test.ts          |  42 +++----
 apps/extension/src/content/orchestrator.ts    |   3 +-
 apps/extension/src/options/i18n/de.ts         |   5 +-
 apps/extension/src/options/i18n/en.ts         |   5 +-
 apps/extension/src/options/i18n/es.ts         |   5 +-
 apps/extension/src/options/i18n/fr.ts         |   5 +-
 apps/extension/src/options/i18n/ja.ts         |   5 +-
 apps/extension/src/options/i18n/ko.ts         |   5 +-
 apps/extension/src/options/i18n/types.ts      |   2 +
 apps/extension/src/options/i18n/zh-CN.ts      |   4 +-
 apps/extension/src/options/i18n/zh-TW.ts      |   4 +-
 .../src/options/optionsLayout.test.ts         |   4 +-
 .../src/options/providerSettings.test.ts      |  35 +++++-
 .../extension/src/options/providerSettings.ts |   3 +-
 apps/extension/src/shared/defaults.test.ts    |   5 +-
 apps/extension/src/shared/defaults.ts         |   4 +
 apps/extension/src/shared/localProviders.ts   |  11 ++
 .../src/shared/migrations/versions/v0.ts      |   2 +-
 apps/extension/src/shared/types.ts            |   2 +-
 26 files changed, 317 insertions(+), 59 deletions(-)
 create mode 100644 apps/extension/src/shared/localProviders.ts

diff --git a/apps/extension/public/options.html b/apps/extension/public/options.html
index a3b8687..4875eca 100644
--- a/apps/extension/public/options.html
+++ b/apps/extension/public/options.html
@@ -22,6 +22,7 @@ <h2 data-i18n="provider">Provider</h2>
                 <option value="anthropic">Anthropic Claude</option>
                 <option value="google">Google Gemini</option>
                 <option value="openai-compatible">OpenAI Compatible</option>
+                <option value="anthropic-compatible">Anthropic Compatible</option>
               </select>
             </label>
             <fieldset data-provider-section="openai-compatible">
@@ -37,10 +38,6 @@ <h2 data-i18n="provider">Provider</h2>
                 </select>
                 <span class="hint" data-i18n="endpointPresetHint">Presets switch the provider to OpenAI Compatible and fill the endpoint.</span>
               </label>
-              <label>
-                <span data-i18n="providerEndpoint">Endpoint URL</span>
-                <input name="providerEndpoint" type="url" required />
-              </label>
               <label class="checkbox">
                 <input name="openAICompatibleJsonMode" type="checkbox" />
                 <span>
@@ -49,10 +46,22 @@ <h2 data-i18n="provider">Provider</h2>
                 </span>
               </label>
             </fieldset>
+            <fieldset data-provider-section="anthropic-compatible">
+              <legend data-i18n="localAnthropicPresets">Local Anthropic-compatible endpoint</legend>
+              <p class="hint" data-i18n="localAnthropicEndpointHint">
+                Use an Anthropic Messages API endpoint such as http://localhost:8000/v1/messages.
+              </p>
+            </fieldset>
+            <label data-provider-section="openai-compatible anthropic-compatible">
+              <span data-i18n="providerEndpoint">Endpoint URL</span>
+              <input name="providerEndpoint" type="url" required />
+            </label>
             <label data-field="api-key">
               <span data-i18n="apiKey">API key</span>
               <input name="apiKey" type="password" autocomplete="off" />
-              <span class="hint" data-i18n="apiKeyHint">Paste the raw provider API key. Local OpenAI-compatible endpoints can leave this empty.</span>
+              <span class="hint" data-i18n="apiKeyHint">
+                Paste the raw provider API key. Local OpenAI-compatible and Anthropic-compatible endpoints can leave this empty.
+              </span>
             </label>
             <label>
               <span data-i18n="model">Model</span>
diff --git a/apps/extension/src/background/providers/anthropic.test.ts b/apps/extension/src/background/providers/anthropic.test.ts
index df8bae8..f2a9fdf 100644
--- a/apps/extension/src/background/providers/anthropic.test.ts
+++ b/apps/extension/src/background/providers/anthropic.test.ts
@@ -1,7 +1,7 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { DEFAULT_SETTINGS } from "../../shared/defaults";
 import type { ExtensionSettings, TextSegment } from "../../shared/types";
-import { anthropicProvider } from "./anthropic";
+import { anthropicCompatibleProvider, anthropicProvider } from "./anthropic";
 
 const segments: TextSegment[] = [
   { id: "a", text: "Hello" },
@@ -119,6 +119,107 @@ describe("anthropicProvider.translate", () => {
   });
 });
 
+describe("anthropicCompatibleProvider.translate", () => {
+  it("uses Bearer auth and omits browser-access header when api key is provided", async () => {
+    const body = JSON.stringify({
+      content: [
+        {
+          type: "tool_use",
+          name: "return_translations",
+          input: { translations: [{ id: "a", text: "你好" }] }
+        }
+      ]
+    });
+    const { fetch: stub, calls } = stubFetch(new Response(body, { status: 200 }));
+    vi.stubGlobal("fetch", stub);
+
+    const results = await anthropicCompatibleProvider.translate(
+      segments,
+      makeSettings({
+        provider: "anthropic-compatible",
+        apiKey: "test-key",
+        providerEndpoint: "http://localhost:8000/v1/messages"
+      })
+    );
+
+    expect(results).toEqual([{ id: "a", text: "你好" }]);
+    const headers = calls[0].init.headers as Record<string, string>;
+    expect(headers.Authorization).toBe("Bearer test-key");
+    expect(headers["x-api-key"]).toBeUndefined();
+    expect(headers["anthropic-dangerous-direct-browser-access"]).toBeUndefined();
+    expect(headers["anthropic-version"]).toBe("2023-06-01");
+  });
+
+  it("omits Authorization header when api key is empty", async () => {
+    const body = JSON.stringify({
+      content: [
+        {
+          type: "tool_use",
+          name: "return_translations",
+          input: { translations: [{ id: "a", text: "你好" }] }
+        }
+      ]
+    });
+    const { fetch: stub, calls } = stubFetch(new Response(body, { status: 200 }));
+    vi.stubGlobal("fetch", stub);
+
+    const results = await anthropicCompatibleProvider.translate(
+      segments,
+      makeSettings({
+        provider: "anthropic-compatible",
+        apiKey: "",
+        providerEndpoint: "http://localhost:8000/v1/messages"
+      })
+    );
+
+    expect(results).toEqual([{ id: "a", text: "你好" }]);
+    const headers = calls[0].init.headers as Record<string, string>;
+    expect(headers.Authorization).toBeUndefined();
+    expect(headers["x-api-key"]).toBeUndefined();
+  });
+});
+
+describe("anthropicCompatibleProvider.listModels", () => {
+  it("uses Bearer auth when api key is provided", async () => {
+    const body = JSON.stringify({ data: [{ id: "local-model" }] });
+    const { fetch: stub, calls } = stubFetch(new Response(body, { status: 200 }));
+    vi.stubGlobal("fetch", stub);
+
+    const models = await anthropicCompatibleProvider.listModels(
+      makeSettings({
+        provider: "anthropic-compatible",
+        apiKey: "cloud-key",
+        providerEndpoint: "http://localhost:8000/v1/messages"
+      })
+    );
+
+    expect(models).toEqual([{ id: "local-model" }]);
+    expect(calls[0].url).toBe("http://localhost:8000/v1/models");
+    const headers = calls[0].init.headers as Record<string, string>;
+    expect(headers.Authorization).toBe("Bearer cloud-key");
+    expect(headers["x-api-key"]).toBeUndefined();
+  });
+
+  it("omits Authorization header when api key is empty", async () => {
+    const body = JSON.stringify({ data: [{ id: "local-model" }] });
+    const { fetch: stub, calls } = stubFetch(new Response(body, { status: 200 }));
+    vi.stubGlobal("fetch", stub);
+
+    const models = await anthropicCompatibleProvider.listModels(
+      makeSettings({
+        provider: "anthropic-compatible",
+        apiKey: "",
+        providerEndpoint: "http://localhost:8000/v1/messages"
+      })
+    );
+
+    expect(models).toEqual([{ id: "local-model" }]);
+    const headers = calls[0].init.headers as Record<string, string>;
+    expect(headers.Authorization).toBeUndefined();
+    expect(headers["x-api-key"]).toBeUndefined();
+  });
+});
+
 describe("anthropicProvider.listModels", () => {
   it("returns models with display_name mapped to displayName", async () => {
     const body = JSON.stringify({
diff --git a/apps/extension/src/background/providers/anthropic.ts b/apps/extension/src/background/providers/anthropic.ts
index c0cf5bf..d634ee7 100644
--- a/apps/extension/src/background/providers/anthropic.ts
+++ b/apps/extension/src/background/providers/anthropic.ts
@@ -25,6 +25,12 @@ export const anthropicProvider: TranslationProvider = {
   listModels: listAnthropicModels
 };
 
+export const anthropicCompatibleProvider: TranslationProvider = {
+  id: "anthropic-compatible",
+  translate: translateWithAnthropic,
+  listModels: listAnthropicModels
+};
+
 async function translateWithAnthropic(
   segments: TextSegment[],
   settings: ExtensionSettings
@@ -86,14 +92,22 @@ async function listAnthropicModels(settings: ExtensionSettings): Promise<Provide
       (model): model is { id: string; display_name?: string } =>
         typeof model.id === "string" && model.id.length > 0
     )
-    .map((model) => ({ id: model.id, displayName: model.display_name }));
+    .map((model) => ({ id: model.id, ...(model.display_name ? { displayName: model.display_name } : {}) }));
 }
 
 function buildAnthropicHeaders(settings: ExtensionSettings): Record<string, string> {
+  if (settings.provider === "anthropic") {
+    return {
+      "Content-Type": "application/json",
+      "anthropic-version": ANTHROPIC_VERSION,
+      "x-api-key": settings.apiKey,
+      "anthropic-dangerous-direct-browser-access": "true"
+    };
+  }
+
   return {
     "Content-Type": "application/json",
-    "x-api-key": settings.apiKey,
     "anthropic-version": ANTHROPIC_VERSION,
-    "anthropic-dangerous-direct-browser-access": "true"
+    ...(settings.apiKey ? { Authorization: `Bearer ${settings.apiKey}` } : {})
   };
 }
diff --git a/apps/extension/src/background/providers/index.test.ts b/apps/extension/src/background/providers/index.test.ts
index e678996..3358bc5 100644
--- a/apps/extension/src/background/providers/index.test.ts
+++ b/apps/extension/src/background/providers/index.test.ts
@@ -3,7 +3,7 @@ import type { TranslationProviderId } from "../../shared/types";
 import { getProvider } from "./index";
 
 describe("getProvider", () => {
-  it.each<TranslationProviderId>(["openai", "openai-compatible", "anthropic", "google"])(
+  it.each<TranslationProviderId>(["openai", "openai-compatible", "anthropic", "anthropic-compatible", "google"])(
     "returns a provider whose id matches the requested id (%s)",
     (id) => {
       const provider = getProvider(id);
diff --git a/apps/extension/src/background/providers/index.ts b/apps/extension/src/background/providers/index.ts
index 47f772b..f9a0565 100644
--- a/apps/extension/src/background/providers/index.ts
+++ b/apps/extension/src/background/providers/index.ts
@@ -1,5 +1,5 @@
 import type { TranslationProviderId } from "../../shared/types";
-import { anthropicProvider } from "./anthropic";
+import { anthropicCompatibleProvider, anthropicProvider } from "./anthropic";
 import { googleProvider } from "./google";
 import { openaiCompatibleProvider, openaiProvider } from "./openai";
 import type { TranslationProvider } from "./types";
@@ -10,6 +10,7 @@ const REGISTRY: Record<TranslationProviderId, TranslationProvider> = {
   openai: openaiProvider,
   "openai-compatible": openaiCompatibleProvider,
   anthropic: anthropicProvider,
+  "anthropic-compatible": anthropicCompatibleProvider,
   google: googleProvider
 };
 
diff --git a/apps/extension/src/background/serviceWorker.test.ts b/apps/extension/src/background/serviceWorker.test.ts
index a82a10e..f9c0d18 100644
--- a/apps/extension/src/background/serviceWorker.test.ts
+++ b/apps/extension/src/background/serviceWorker.test.ts
@@ -1,5 +1,6 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
-import { CACHE_KEY_PREFIX, DEFAULT_SETTINGS, SETTINGS_KEY } from "../shared/defaults";
+import { CACHE_KEY_PREFIX, DEFAULT_SETTINGS, PROVIDER_DEFAULTS, SETTINGS_KEY } from "../shared/defaults";
+import type { LocalTranslationProviderId } from "../shared/localProviders";
 import type { ExtensionSettings, RuntimeMessage, TextSegment, TranslationResult } from "../shared/types";
 import type * as ServiceWorkerModuleType from "./serviceWorker";
 
@@ -158,6 +159,19 @@ describe("handleMessage TRANSLATE_BATCH", () => {
       });
   }
 
+  function stubAnthropicResponse(translations: TranslationResult[]): void {
+    fetchResponder = () =>
+      jsonResponse({
+        content: [
+          {
+            type: "tool_use",
+            name: "return_translations",
+            input: { translations }
+          }
+        ]
+      });
+  }
+
   it("returns an error when api key is missing for a non-local provider", async () => {
     saveSettings({ provider: "openai", apiKey: "" });
     const { handleMessage } = await loadModule();
@@ -169,16 +183,28 @@ describe("handleMessage TRANSLATE_BATCH", () => {
     expect(fetchCalls).toHaveLength(0);
   });
 
-  it("allows openai-compatible without an api key", async () => {
-    saveSettings({ provider: "openai-compatible", apiKey: "" });
-    stubOpenAIResponse([{ id: "s1", text: "你好" }]);
-    const { handleMessage } = await loadModule();
+  it.each<LocalTranslationProviderId>(["openai-compatible", "anthropic-compatible"])(
+    "allows %s without an api key",
+    async (provider) => {
+      saveSettings({
+        provider,
+        apiKey: "",
+        providerEndpoint: PROVIDER_DEFAULTS[provider].providerEndpoint,
+        model: PROVIDER_DEFAULTS[provider].model
+      });
+      if (provider === "openai-compatible") {
+        stubOpenAIResponse([{ id: "s1", text: "你好" }]);
+      } else {
+        stubAnthropicResponse([{ id: "s1", text: "你好" }]);
+      }
+      const { handleMessage } = await loadModule();
 
-    const result = (await handleMessage({ type: "TRANSLATE_BATCH", segments })) as TranslateBatchResult;
+      const result = (await handleMessage({ type: "TRANSLATE_BATCH", segments })) as TranslateBatchResult;
 
-    expect(result.ok).toBe(true);
-    expect(result.results).toEqual([{ id: "s1", text: "你好" }]);
-  });
+      expect(result.ok).toBe(true);
+      expect(result.results).toEqual([{ id: "s1", text: "你好" }]);
+    }
+  );
 
   it("dispatches through the registry and caches results in session and persistent stores", async () => {
     saveSettings({ provider: "openai", apiKey: "sk-test", cacheMode: "persistent", targetLanguage: "繁體中文" });
@@ -254,6 +280,35 @@ describe("handleMessage LIST_MODELS", () => {
     expect(result.error).toMatch(/Configure an API key/);
   });
 
+  it.each<LocalTranslationProviderId>(["openai-compatible", "anthropic-compatible"])(
+    "allows %s to list models without an api key",
+    async (provider) => {
+      fetchResponder = (url) => {
+        if (provider === "anthropic-compatible") {
+          expect(url).toBe("http://localhost:8000/v1/models");
+          return jsonResponse({ data: [{ id: "local-model" }] });
+        }
+        return jsonResponse({ data: [{ id: "gpt-4o-mini" }] });
+      };
+      const { handleMessage } = await loadModule();
+
+      const result = (await handleMessage({
+        type: "LIST_MODELS",
+        settings: makeSettings({
+          provider,
+          apiKey: "",
+          providerEndpoint: PROVIDER_DEFAULTS[provider].providerEndpoint,
+          model: PROVIDER_DEFAULTS[provider].model
+        })
+      })) as ListModelsResult;
+
+      expect(result.ok).toBe(true);
+      expect(result.models).toEqual([
+        { id: provider === "anthropic-compatible" ? "local-model" : "gpt-4o-mini" }
+      ]);
+    }
+  );
+
   it("dispatches to the registered provider", async () => {
     fetchResponder = () => jsonResponse({ data: [{ id: "gpt-4o" }, { id: "gpt-4o-mini" }] });
     const { handleMessage } = await loadModule();
diff --git a/apps/extension/src/background/serviceWorker.ts b/apps/extension/src/background/serviceWorker.ts
index 3090a73..360e388 100644
--- a/apps/extension/src/background/serviceWorker.ts
+++ b/apps/extension/src/background/serviceWorker.ts
@@ -8,6 +8,7 @@ import type {
   TranslationResult
 } from "../shared/types";
 import { hashText } from "../shared/hash";
+import { isLocalTranslationProvider } from "../shared/localProviders";
 import { getProvider } from "./providers";
 import { installUpgradeLifecycle } from "./upgradeLifecycle";
 
@@ -53,7 +54,7 @@ async function translateBatch(segments: TextSegment[]): Promise<TranslateBatchRe
   const settings = await getSettings();
   const apiKey = normalizeApiKey(settings.apiKey);
 
-  if (!apiKey && settings.provider !== "openai-compatible") {
+  if (!apiKey && !isLocalTranslationProvider(settings.provider)) {
     return { ok: false, error: "Configure an API key in Margin options before translating." };
   }
 
@@ -124,7 +125,7 @@ function getRuntimeMessageType(message: unknown): string {
 async function listProviderModels(
   settings: ExtensionSettings
 ): Promise<{ ok: boolean; models?: ProviderModel[]; error?: string }> {
-  if (!settings.apiKey && settings.provider !== "openai-compatible") {
+  if (!settings.apiKey && !isLocalTranslationProvider(settings.provider)) {
     return { ok: false, error: "Configure an API key before fetching models." };
   }
 
diff --git a/apps/extension/src/content/orchestrator.test.ts b/apps/extension/src/content/orchestrator.test.ts
index 190ab7f..d7b0af9 100644
--- a/apps/extension/src/content/orchestrator.test.ts
+++ b/apps/extension/src/content/orchestrator.test.ts
@@ -1,5 +1,6 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { DEFAULT_SETTINGS } from "../shared/defaults";
+import type { LocalTranslationProviderId } from "../shared/localProviders";
 import type { ExtensionSettings, RuntimeMessage, TextSegment, TranslationResult } from "../shared/types";
 import { createOrchestrator, type ContentOrchestrator } from "./orchestrator";
 import { TRANSLATION_CLASS, TRANSLATED_ATTR } from "./translationRenderer";
@@ -300,25 +301,28 @@ describe("createOrchestrator — error paths", () => {
 });
 
 describe("createOrchestrator — provider-specific queue", () => {
-  it("uses smaller batch/concurrency for openai-compatible runtimes", async () => {
-    useRouter({ settings: { ...DEFAULT_SETTINGS, provider: "openai-compatible" } });
-
-    const paragraphs = Array.from({ length: 5 }, (_, i) => `${SAMPLE_PARAGRAPH} extra ${i}`);
-    seedDocument(`<main>${paragraphs.map((text) => `<p>${text}</p>`).join("")}</main>`);
-    const orchestrator = createTestOrchestrator();
-
-    await orchestrator.setEnabled(true);
-    await vi.waitFor(() => {
-      expect(document.querySelectorAll(`p[${TRANSLATED_ATTR}="done"]`).length).toBeGreaterThan(0);
-    });
-
-    const batches = sendMessageMock.mock.calls
-      .map(([msg]) => msg)
-      .filter((msg): msg is Extract<RuntimeMessage, { type: "TRANSLATE_BATCH" }> => msg.type === "TRANSLATE_BATCH")
-      .map((msg) => msg.segments.length);
-    expect(batches.length).toBeGreaterThanOrEqual(2);
-    expect(Math.max(...batches)).toBeLessThanOrEqual(3);
-  });
+  it.each<LocalTranslationProviderId>(["openai-compatible", "anthropic-compatible"])(
+    "uses smaller batch/concurrency for %s runtimes",
+    async (provider) => {
+      useRouter({ settings: { ...DEFAULT_SETTINGS, provider } });
+
+      const paragraphs = Array.from({ length: 5 }, (_, i) => `${SAMPLE_PARAGRAPH} extra ${i}`);
+      seedDocument(`<main>${paragraphs.map((text) => `<p>${text}</p>`).join("")}</main>`);
+      const orchestrator = createTestOrchestrator();
+
+      await orchestrator.setEnabled(true);
+      await vi.waitFor(() => {
+        expect(document.querySelectorAll(`p[${TRANSLATED_ATTR}="done"]`).length).toBeGreaterThan(0);
+      });
+
+      const batches = sendMessageMock.mock.calls
+        .map(([msg]) => msg)
+        .filter((msg): msg is Extract<RuntimeMessage, { type: "TRANSLATE_BATCH" }> => msg.type === "TRANSLATE_BATCH")
+        .map((msg) => msg.segments.length);
+      expect(batches.length).toBeGreaterThanOrEqual(2);
+      expect(Math.max(...batches)).toBeLessThanOrEqual(3);
+    }
+  );
 });
 
 describe("createOrchestrator — DOM observers", () => {
diff --git a/apps/extension/src/content/orchestrator.ts b/apps/extension/src/content/orchestrator.ts
index 195234b..e3b0bbc 100644
--- a/apps/extension/src/content/orchestrator.ts
+++ b/apps/extension/src/content/orchestrator.ts
@@ -1,3 +1,4 @@
+import { isLocalTranslationProvider } from "../shared/localProviders";
 import { normalizeText } from "../shared/text";
 import type { ExtensionSettings, PageDebugState, TranslationProviderId, TranslationResult } from "../shared/types";
 import type { BlockCandidate } from "./blockCandidates";
@@ -312,7 +313,7 @@ export function createOrchestrator(options: ContentOrchestratorOptions): Content
 
   function configureTranslationQueue(provider: TranslationProviderId): void {
     queue.configure(
-      provider === "openai-compatible"
+      isLocalTranslationProvider(provider)
         ? { batchSize: LOCAL_BATCH_SIZE, concurrency: LOCAL_CONCURRENCY }
         : { batchSize: BATCH_SIZE, concurrency: CONCURRENCY }
     );
diff --git a/apps/extension/src/options/i18n/de.ts b/apps/extension/src/options/i18n/de.ts
index 5c792cf..38c8c09 100644
--- a/apps/extension/src/options/i18n/de.ts
+++ b/apps/extension/src/options/i18n/de.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const de = {
   apiKey: "API key",
-  apiKeyHint: "Fuege den rohen provider API key ein. Lokale OpenAI-compatible endpoints koennen leer bleiben.",
+  apiKeyHint: "Fuege den rohen provider API key ein. Lokale OpenAI-compatible und Anthropic-compatible endpoints koennen leer bleiben.",
   cacheBehavior: "Cache-Verhalten",
   cacheBehaviorHint:
     "Nur Sitzung ist der privacy-first Standard. Persistenter Cache speichert Uebersetzungen in diesem Browserprofil, bis du den Cache leerst.",
@@ -28,6 +28,9 @@ export const de = {
   fetchModelsBusy: "Wird abgerufen...",
   floatingButton: "Schwebender Uebersetzen-Button",
   floatingButtonHint: "Zeigt einen kleinen Seitenbutton, der erst nach einem Klick uebersetzt.",
+  localAnthropicEndpointHint:
+    "Verwende einen Anthropic Messages API endpoint, z. B. http://localhost:8000/v1/messages.",
+  localAnthropicPresets: "Lokaler Anthropic-compatible endpoint",
   localJsonHint: "Deaktivieren, wenn ein lokaler runtime das OpenAI response_format Feld ablehnt.",
   localJsonMode: "JSON mode anfordern",
   localPresetDefault: "Lokalen runtime waehlen",
diff --git a/apps/extension/src/options/i18n/en.ts b/apps/extension/src/options/i18n/en.ts
index 3dc9640..77247d3 100644
--- a/apps/extension/src/options/i18n/en.ts
+++ b/apps/extension/src/options/i18n/en.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const en = {
   apiKey: "API key",
-  apiKeyHint: "Paste the raw provider API key. Local OpenAI-compatible endpoints can leave this empty.",
+  apiKeyHint: "Paste the raw provider API key. Local OpenAI-compatible and Anthropic-compatible endpoints can leave this empty.",
   cacheBehavior: "Cache behavior",
   cacheBehaviorHint:
     "Session only is the privacy-first default. Persistent stores translated text in this browser profile until cleared.",
@@ -28,6 +28,9 @@ export const en = {
   fetchModelsBusy: "Fetching...",
   floatingButton: "Floating translate button",
   floatingButtonHint: "Show a small page button that only translates after you click it.",
+  localAnthropicEndpointHint:
+    "Use an Anthropic Messages API endpoint such as http://localhost:8000/v1/messages.",
+  localAnthropicPresets: "Local Anthropic-compatible endpoint",
   localJsonHint: "Disable this if a local runtime rejects the OpenAI response_format field.",
   localJsonMode: "Request JSON mode",
   localPresetDefault: "Select a local runtime",
diff --git a/apps/extension/src/options/i18n/es.ts b/apps/extension/src/options/i18n/es.ts
index f47b8c9..969a07c 100644
--- a/apps/extension/src/options/i18n/es.ts
+++ b/apps/extension/src/options/i18n/es.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const es = {
   apiKey: "Clave de API",
-  apiKeyHint: "Pega la API key sin procesar del provider. Los endpoints locales OpenAI-compatible pueden dejarlo vacío.",
+  apiKeyHint: "Pega la API key sin procesar del provider. Los endpoints locales OpenAI-compatible y Anthropic-compatible pueden dejarlo vacío.",
   cacheBehavior: "Comportamiento de caché",
   cacheBehaviorHint:
     "Solo sesion es el valor predeterminado privacy-first. La cache persistente guarda traducciones en este perfil del navegador hasta que la borres.",
@@ -28,6 +28,9 @@ export const es = {
   fetchModelsBusy: "Obteniendo...",
   floatingButton: "Boton flotante de traduccion",
   floatingButtonHint: "Muestra un boton pequeno en la pagina que solo traduce despues de hacer clic.",
+  localAnthropicEndpointHint:
+    "Usa un endpoint de Anthropic Messages API, por ejemplo http://localhost:8000/v1/messages.",
+  localAnthropicPresets: "Endpoint local Anthropic-compatible",
   localJsonHint: "Desactívalo si un runtime local rechaza el campo OpenAI response_format.",
   localJsonMode: "Solicitar modo JSON",
   localPresetDefault: "Selecciona un runtime local",
diff --git a/apps/extension/src/options/i18n/fr.ts b/apps/extension/src/options/i18n/fr.ts
index e4c9ef0..b972666 100644
--- a/apps/extension/src/options/i18n/fr.ts
+++ b/apps/extension/src/options/i18n/fr.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const fr = {
   apiKey: "Cle API",
-  apiKeyHint: "Collez l'API key brute du provider. Les endpoints locaux OpenAI-compatible peuvent rester vides.",
+  apiKeyHint: "Collez l'API key brute du provider. Les endpoints locaux OpenAI-compatible et Anthropic-compatible peuvent rester vides.",
   cacheBehavior: "Comportement du cache",
   cacheBehaviorHint:
     "Session uniquement est le choix privacy-first par defaut. Le cache persistant conserve les traductions dans ce profil de navigateur jusqu'a ce que vous le vidiez.",
@@ -28,6 +28,9 @@ export const fr = {
   fetchModelsBusy: "Chargement...",
   floatingButton: "Bouton flottant de traduction",
   floatingButtonHint: "Affiche un petit bouton sur la page qui ne traduit qu'apres un clic.",
+  localAnthropicEndpointHint:
+    "Utilisez un endpoint Anthropic Messages API, par exemple http://localhost:8000/v1/messages.",
+  localAnthropicPresets: "Endpoint local Anthropic-compatible",
   localJsonHint: "Desactivez ceci si un runtime local rejette le champ OpenAI response_format.",
   localJsonMode: "Demander le mode JSON",
   localPresetDefault: "Selectionner un runtime local",
diff --git a/apps/extension/src/options/i18n/ja.ts b/apps/extension/src/options/i18n/ja.ts
index 9ffcc2f..a557aad 100644
--- a/apps/extension/src/options/i18n/ja.ts
+++ b/apps/extension/src/options/i18n/ja.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const ja = {
   apiKey: "API キー",
-  apiKeyHint: "Provider の生 API key を貼り付けます。Local OpenAI-compatible endpoint では空欄にできます。",
+  apiKeyHint: "Provider の生 API key を貼り付けます。Local OpenAI-compatible と Anthropic-compatible endpoint では空欄にできます。",
   cacheBehavior: "キャッシュ動作",
   cacheBehaviorHint:
     "「セッションのみ」がプライバシー優先の既定値です。「永続」は、消去するまで翻訳文をこのブラウザ profile に保存します。",
@@ -28,6 +28,9 @@ export const ja = {
   fetchModelsBusy: "取得中...",
   floatingButton: "フローティング翻訳ボタン",
   floatingButtonHint: "ページ上に小さなボタンを表示し、クリックした後だけ翻訳します。",
+  localAnthropicEndpointHint:
+    "Anthropic Messages API endpoint（例: http://localhost:8000/v1/messages）を使用してください。",
+  localAnthropicPresets: "ローカル Anthropic-compatible endpoint",
   localJsonHint: "Local runtime が OpenAI response_format を拒否する場合はオフにしてください。",
   localJsonMode: "JSON mode を要求",
   localPresetDefault: "Local runtime を選択",
diff --git a/apps/extension/src/options/i18n/ko.ts b/apps/extension/src/options/i18n/ko.ts
index 58b35ed..96f4d74 100644
--- a/apps/extension/src/options/i18n/ko.ts
+++ b/apps/extension/src/options/i18n/ko.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const ko = {
   apiKey: "API 키",
-  apiKeyHint: "Provider 원본 API key 를 붙여 넣으세요. Local OpenAI-compatible endpoint 는 비워 둘 수 있습니다.",
+  apiKeyHint: "Provider 원본 API key 를 붙여 넣으세요. Local OpenAI-compatible 및 Anthropic-compatible endpoint 는 비워 둘 수 있습니다.",
   cacheBehavior: "캐시 방식",
   cacheBehaviorHint:
     "세션만이 개인정보 우선 기본값입니다. 영구 저장은 지울 때까지 번역문을 이 브라우저 profile 에 저장합니다.",
@@ -28,6 +28,9 @@ export const ko = {
   fetchModelsBusy: "가져오는 중...",
   floatingButton: "플로팅 번역 버튼",
   floatingButtonHint: "웹페이지에 작은 버튼을 표시하고, 클릭한 뒤에만 번역합니다.",
+  localAnthropicEndpointHint:
+    "Anthropic Messages API endpoint(예: http://localhost:8000/v1/messages)를 사용하세요.",
+  localAnthropicPresets: "로컬 Anthropic-compatible endpoint",
   localJsonHint: "Local runtime 이 OpenAI response_format 필드를 거부하면 이 옵션을 끄세요.",
   localJsonMode: "JSON mode 요청",
   localPresetDefault: "Local runtime 선택",
diff --git a/apps/extension/src/options/i18n/types.ts b/apps/extension/src/options/i18n/types.ts
index 8406d43..88b2ac1 100644
--- a/apps/extension/src/options/i18n/types.ts
+++ b/apps/extension/src/options/i18n/types.ts
@@ -25,6 +25,8 @@ export const MESSAGE_KEYS = [
   "fetchModelsBusy",
   "floatingButton",
   "floatingButtonHint",
+  "localAnthropicEndpointHint",
+  "localAnthropicPresets",
   "localJsonHint",
   "localJsonMode",
   "localPresetDefault",
diff --git a/apps/extension/src/options/i18n/zh-CN.ts b/apps/extension/src/options/i18n/zh-CN.ts
index 95aa986..5fd9861 100644
--- a/apps/extension/src/options/i18n/zh-CN.ts
+++ b/apps/extension/src/options/i18n/zh-CN.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const zhCN = {
   apiKey: "API 密钥",
-  apiKeyHint: "粘贴原始 provider API key。Local OpenAI-compatible endpoint 可以留空。",
+  apiKeyHint: "粘贴原始 provider API key。Local OpenAI-compatible 与 Anthropic-compatible endpoint 可以留空。",
   cacheBehavior: "缓存行为",
   cacheBehaviorHint:
     "“仅本次浏览会话”是隐私优先的默认值。“持久保存”会把译文存在此浏览器 profile，直到你清除缓存。",
@@ -28,6 +28,8 @@ export const zhCN = {
   fetchModelsBusy: "获取中...",
   floatingButton: "浮动翻译按钮",
   floatingButtonHint: "在网页上显示小型按钮，只有点击后才会开始翻译。",
+  localAnthropicEndpointHint: "请使用 Anthropic Messages API endpoint，例如 http://localhost:8000/v1/messages。",
+  localAnthropicPresets: "本地 Anthropic-compatible endpoint",
   localJsonHint: "如果 local runtime 拒绝 OpenAI response_format 字段，请关闭此选项。",
   localJsonMode: "要求 JSON mode",
   localPresetDefault: "选择 local runtime",
diff --git a/apps/extension/src/options/i18n/zh-TW.ts b/apps/extension/src/options/i18n/zh-TW.ts
index 5f9d190..0672bb2 100644
--- a/apps/extension/src/options/i18n/zh-TW.ts
+++ b/apps/extension/src/options/i18n/zh-TW.ts
@@ -2,7 +2,7 @@ import type { MessageDictionary } from "./types";
 
 export const zhTW = {
   apiKey: "API 金鑰",
-  apiKeyHint: "貼上原始 provider API key。Local OpenAI-compatible endpoint 可以留空。",
+  apiKeyHint: "貼上原始 provider API key。Local OpenAI-compatible 與 Anthropic-compatible endpoint 可以留空。",
   cacheBehavior: "快取行為",
   cacheBehaviorHint:
     "「僅本次瀏覽階段」是隱私優先的預設值。「持久保存」會把譯文存在此瀏覽器 profile，直到你清除快取。",
@@ -28,6 +28,8 @@ export const zhTW = {
   fetchModelsBusy: "取得中...",
   floatingButton: "浮動翻譯按鈕",
   floatingButtonHint: "在網頁上顯示小型按鈕，只有點擊後才會開始翻譯。",
+  localAnthropicEndpointHint: "請使用 Anthropic Messages API endpoint，例如 http://localhost:8000/v1/messages。",
+  localAnthropicPresets: "本機 Anthropic-compatible endpoint",
   localJsonHint: "如果 local runtime 拒絕 OpenAI response_format 欄位，請關閉此選項。",
   localJsonMode: "要求 JSON mode",
   localPresetDefault: "選擇 local runtime",
diff --git a/apps/extension/src/options/optionsLayout.test.ts b/apps/extension/src/options/optionsLayout.test.ts
index 89d1217..1d664b7 100644
--- a/apps/extension/src/options/optionsLayout.test.ts
+++ b/apps/extension/src/options/optionsLayout.test.ts
@@ -15,13 +15,13 @@ describe("options layout", () => {
     expect(fetchButton?.closest("label")).toBe(modelSelect?.closest("label"));
   });
 
-  it("scopes the provider endpoint to the OpenAI Compatible section", () => {
+  it("scopes the provider endpoint to local compatible provider sections", () => {
     const document = createDocument(optionsHtml);
     const endpointInput = document.querySelector<HTMLInputElement>('[name="providerEndpoint"]');
 
     expect(endpointInput).not.toBeNull();
     expect(endpointInput?.closest("[data-provider-section]")?.getAttribute("data-provider-section")).toBe(
-      "openai-compatible"
+      "openai-compatible anthropic-compatible"
     );
   });
 
diff --git a/apps/extension/src/options/providerSettings.test.ts b/apps/extension/src/options/providerSettings.test.ts
index 8b88d2a..919e5f7 100644
--- a/apps/extension/src/options/providerSettings.test.ts
+++ b/apps/extension/src/options/providerSettings.test.ts
@@ -1,5 +1,5 @@
 import { beforeEach, describe, expect, it, vi } from "vitest";
-import { DEFAULT_SETTINGS } from "../shared/defaults";
+import { DEFAULT_SETTINGS, PROVIDER_DEFAULTS } from "../shared/defaults";
 import { initializeProviderSettings } from "./providerSettings";
 import { readForm } from "./settingsForm";
 
@@ -8,6 +8,7 @@ function setupOptionsDom(): void {
     <select name="provider">
       <option value="openai">OpenAI</option>
       <option value="openai-compatible">OpenAI Compatible</option>
+      <option value="anthropic-compatible">Anthropic Compatible</option>
     </select>
     <fieldset data-provider-section="openai-compatible">
       <select id="local-endpoint-preset">
@@ -16,8 +17,11 @@ function setupOptionsDom(): void {
         <option value="http://localhost:8000/v1/chat/completions">omlx</option>
       </select>
       <input name="openAICompatibleJsonMode" type="checkbox" />
-      <input name="providerEndpoint" type="url" />
     </fieldset>
+    <fieldset data-provider-section="anthropic-compatible"></fieldset>
+    <label data-provider-section="openai-compatible anthropic-compatible">
+      <input name="providerEndpoint" type="url" />
+    </label>
     <input name="apiKey" />
     <select id="model-select" name="model"></select>
     <button id="fetch-models" type="button">Fetch models</button>
@@ -38,14 +42,39 @@ describe("provider settings", () => {
     initializeProviderSettings({ locale: "en", readForm, setStatus: vi.fn() });
 
     expect(document.querySelector<HTMLElement>("[data-provider-section='openai-compatible']")?.hidden).toBe(true);
+    expect(document.querySelector<HTMLElement>("[data-provider-section='anthropic-compatible']")?.hidden).toBe(true);
+    expect(
+      document.querySelector<HTMLElement>("[data-provider-section='openai-compatible anthropic-compatible']")?.hidden
+    ).toBe(true);
 
     const providerInput = document.querySelector<HTMLSelectElement>('[name="provider"]')!;
     providerInput.value = "openai-compatible";
     providerInput.dispatchEvent(new Event("change"));
 
     expect(document.querySelector<HTMLElement>("[data-provider-section='openai-compatible']")?.hidden).toBe(false);
+    expect(document.querySelector<HTMLElement>("[data-provider-section='anthropic-compatible']")?.hidden).toBe(true);
+    expect(
+      document.querySelector<HTMLElement>("[data-provider-section='openai-compatible anthropic-compatible']")?.hidden
+    ).toBe(false);
+    expect(document.querySelector<HTMLInputElement>('[name="providerEndpoint"]')?.value).toBe(
+      PROVIDER_DEFAULTS["openai-compatible"].providerEndpoint
+    );
+  });
+
+  it("keeps provider endpoints scoped to Anthropic Compatible", () => {
+    initializeProviderSettings({ locale: "en", readForm, setStatus: vi.fn() });
+
+    const providerInput = document.querySelector<HTMLSelectElement>('[name="provider"]')!;
+    providerInput.value = "anthropic-compatible";
+    providerInput.dispatchEvent(new Event("change"));
+
+    expect(document.querySelector<HTMLElement>("[data-provider-section='openai-compatible']")?.hidden).toBe(true);
+    expect(document.querySelector<HTMLElement>("[data-provider-section='anthropic-compatible']")?.hidden).toBe(false);
+    expect(
+      document.querySelector<HTMLElement>("[data-provider-section='openai-compatible anthropic-compatible']")?.hidden
+    ).toBe(false);
     expect(document.querySelector<HTMLInputElement>('[name="providerEndpoint"]')?.value).toBe(
-      "http://localhost:1234/v1/chat/completions"
+      PROVIDER_DEFAULTS["anthropic-compatible"].providerEndpoint
     );
   });
 
diff --git a/apps/extension/src/options/providerSettings.ts b/apps/extension/src/options/providerSettings.ts
index 0508e91..e71bcde 100644
--- a/apps/extension/src/options/providerSettings.ts
+++ b/apps/extension/src/options/providerSettings.ts
@@ -53,7 +53,8 @@ export function initializeProviderSettings({ locale, readForm, setStatus }: Prov
 
 function updateProviderSections(provider: TranslationProviderId): void {
   document.querySelectorAll<HTMLElement>("[data-provider-section]").forEach((section) => {
-    section.hidden = section.dataset.providerSection !== provider;
+    const sections = (section.dataset.providerSection ?? "").split(/\s+/).filter(Boolean);
+    section.hidden = sections.length > 0 && !sections.includes(provider);
   });
 }
 
diff --git a/apps/extension/src/shared/defaults.test.ts b/apps/extension/src/shared/defaults.test.ts
index 97794e6..f06fb5b 100644
--- a/apps/extension/src/shared/defaults.test.ts
+++ b/apps/extension/src/shared/defaults.test.ts
@@ -3,7 +3,7 @@ import { DEFAULT_SETTINGS, PROVIDER_DEFAULTS } from "./defaults";
 
 describe("provider defaults", () => {
   it("defines defaults for every supported provider", () => {
-    expect(Object.keys(PROVIDER_DEFAULTS).sort()).toEqual(["anthropic", "google", "openai", "openai-compatible"]);
+    expect(Object.keys(PROVIDER_DEFAULTS).sort()).toEqual(["anthropic", "anthropic-compatible", "google", "openai", "openai-compatible"]);
   });
 
   it("uses the OpenAI provider as the initial default", () => {
@@ -24,5 +24,8 @@ describe("provider defaults", () => {
     expect(PROVIDER_DEFAULTS["openai-compatible"].providerEndpoint).toBe(
       "http://localhost:1234/v1/chat/completions"
     );
+    expect(PROVIDER_DEFAULTS["anthropic-compatible"].providerEndpoint).toBe(
+      "http://localhost:8000/v1/messages"
+    );
   });
 });
diff --git a/apps/extension/src/shared/defaults.ts b/apps/extension/src/shared/defaults.ts
index f710790..6aa82e8 100644
--- a/apps/extension/src/shared/defaults.ts
+++ b/apps/extension/src/shared/defaults.ts
@@ -19,6 +19,10 @@ export const PROVIDER_DEFAULTS: Record<
   "openai-compatible": {
     providerEndpoint: "http://localhost:1234/v1/chat/completions",
     model: "local-model"
+  },
+  "anthropic-compatible": {
+    providerEndpoint: "http://localhost:8000/v1/messages",
+    model: "local-model"
   }
 };
 
diff --git a/apps/extension/src/shared/localProviders.ts b/apps/extension/src/shared/localProviders.ts
new file mode 100644
index 0000000..398ae59
--- /dev/null
+++ b/apps/extension/src/shared/localProviders.ts
@@ -0,0 +1,11 @@
+import type { TranslationProviderId } from "./types";
+
+export const LOCAL_TRANSLATION_PROVIDERS = ["openai-compatible", "anthropic-compatible"] as const;
+
+export type LocalTranslationProviderId = (typeof LOCAL_TRANSLATION_PROVIDERS)[number];
+
+export function isLocalTranslationProvider(
+  provider: TranslationProviderId
+): provider is LocalTranslationProviderId {
+  return (LOCAL_TRANSLATION_PROVIDERS as readonly string[]).includes(provider);
+}
diff --git a/apps/extension/src/shared/migrations/versions/v0.ts b/apps/extension/src/shared/migrations/versions/v0.ts
index fb39cf1..0633417 100644
--- a/apps/extension/src/shared/migrations/versions/v0.ts
+++ b/apps/extension/src/shared/migrations/versions/v0.ts
@@ -31,7 +31,7 @@ export interface ExtensionSettingsV0 {
   showFloatingButton?: boolean;
 }
 
-const PROVIDERS: readonly TranslationProviderId[] = ["openai", "anthropic", "google", "openai-compatible"];
+const PROVIDERS: readonly TranslationProviderId[] = ["openai", "anthropic", "google", "openai-compatible", "anthropic-compatible"];
 const DISPLAY_STYLES: readonly DisplayStyle[] = ["integrated", "highlighted"];
 const CACHE_MODES: readonly CacheMode[] = ["session", "persistent", "disabled"];
 
diff --git a/apps/extension/src/shared/types.ts b/apps/extension/src/shared/types.ts
index 8e00054..5c4b2cd 100644
--- a/apps/extension/src/shared/types.ts
+++ b/apps/extension/src/shared/types.ts
@@ -4,7 +4,7 @@ export type DisplayStyle = ModernDisplayStyle | LegacyDisplayStyle;
 
 export type CacheMode = "session" | "persistent" | "disabled";
 
-export type TranslationProviderId = "openai" | "anthropic" | "google" | "openai-compatible";
+export type TranslationProviderId = "openai" | "anthropic" | "google" | "openai-compatible" | "anthropic-compatible";
 
 export const SETTINGS_VERSION = 1;
 

From 4f2eccf045ee222fcdab0deec995cd6821cdcfe4 Mon Sep 17 00:00:00 2001
From: Yi-Ru Lin <deduce@gmail.com>
Date: Sun, 31 May 2026 21:42:57 -0500
Subject: [PATCH 2/2] Refine Anthropic-compatible provider integration

---
 CHANGELOG.md                                  |  7 +++++
 README.md                                     | 27 ++++++++++++-------
 README.zh-TW.md                               | 27 ++++++++++++-------
 .../background/providers/anthropic.test.ts    |  2 ++
 .../src/background/providers/anthropic.ts     |  9 ++++---
 .../src/content/orchestrator.test.ts          | 26 ++++++++++++++++++
 apps/extension/src/content/orchestrator.ts    |  5 ++--
 apps/extension/src/shared/localProviders.ts   |  5 +++-
 .../src/shared/migrations/versions/v0.test.ts |  6 +++++
 .../src/shared/migrations/versions/v0.ts      |  8 +++---
 10 files changed, 95 insertions(+), 27 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a2526e8..df119d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Anthropic Compatible provider support for local or gateway endpoints that
+  implement the Anthropic Messages-style `/v1/messages` API, including model
+  fetching via `/v1/models`, optional Bearer auth, local-provider concurrency
+  limits, and options-page setup.
+
 ## [0.3.2] - 2026-05-31
 
 ### Added
diff --git a/README.md b/README.md
index bc61c37..994c97b 100644
--- a/README.md
+++ b/README.md
@@ -31,8 +31,8 @@ The extension is usable for normal article pages, legacy text-heavy pages, and s
 - Handle legacy `table`, `font`, and `br`-separated pages.
 - Avoid common non-reading areas such as navigation, forms, buttons, code blocks, hidden text, and page chrome.
 - Use user-configured provider endpoints and API keys.
-- Support OpenAI, Anthropic Claude, and Google Gemini provider adapters.
-- Support local OpenAI-compatible runtimes such as LM Studio, Ollama, llama.cpp server, and omlx (Apple Silicon).
+- Support OpenAI, Anthropic Claude, Google Gemini, and compatible provider adapters.
+- Support local OpenAI-compatible runtimes such as LM Studio, Ollama, llama.cpp server, and omlx (Apple Silicon), plus Anthropic Messages API-compatible endpoints.
 - Fetch provider model lists from the options page.
 - Choose integrated or highlighted translation display styles.
 - Optionally show a floating page button that starts translation only after the user clicks it.
@@ -82,13 +82,14 @@ Anthropic Claude: https://api.anthropic.com/v1/messages
 Google Gemini: https://generativelanguage.googleapis.com/v1beta/models
 ```
 
-The endpoint field is shown only for OpenAI Compatible / Local LLM setups, where the user is expected to choose or enter a local endpoint.
+The endpoint field is shown only for compatible / Local LLM setups, where the user is expected to choose or enter a local endpoint.
 
 The Fetch models action reads available models from the selected provider:
 
 - OpenAI: `GET /v1/models`
 - Anthropic Claude: `GET /v1/models`
 - Google Gemini: `GET /v1beta/models`
+- OpenAI Compatible / Anthropic Compatible: `GET /v1/models`
 
 Fetched models appear in the model selector. Margin keeps the currently configured model as an option when a provider default or previously saved model is not returned by the provider list.
 
@@ -108,34 +109,42 @@ Quoted posts are disabled by default and can be enabled from options. Posts that
 
 ## Local LLMs
 
-Margin supports local LLM runtimes through the OpenAI Compatible provider. This provider uses the OpenAI-style `/v1/chat/completions` API, allows an empty API key, and uses a lower default translation concurrency for local inference.
+Margin supports local LLM runtimes through compatible providers:
 
-Common endpoint presets:
+- OpenAI Compatible uses the OpenAI-style `/v1/chat/completions` API.
+- Anthropic Compatible uses the Anthropic Messages-style `/v1/messages` API with tool `input_schema` structured output. It is a wire-protocol option for compatible local or gateway endpoints, not a separate Anthropic-hosted service.
+
+Both compatible providers allow an empty API key and use lower default translation concurrency for local inference. If an Anthropic-compatible gateway requires a key, Margin sends it as `Authorization: Bearer ...`.
+
+Common compatible endpoints:
 
 ```text
 LM Studio: http://localhost:1234/v1/chat/completions
 Ollama: http://localhost:11434/v1/chat/completions
 llama.cpp server: http://localhost:8080/v1/chat/completions
 omlx: http://localhost:8000/v1/chat/completions
+Generic Anthropic-compatible: http://localhost:8000/v1/messages
+Ollama Anthropic compatibility: http://localhost:11434/v1/messages
 ```
 
 To use a local runtime:
 
 1. Start the local model server.
 2. Open Margin options.
-3. Select OpenAI Compatible as the provider.
-4. Select an endpoint preset, or enter the endpoint URL shown by your runtime.
+3. Select OpenAI Compatible for `/v1/chat/completions`, or Anthropic Compatible for `/v1/messages`.
+4. Select an OpenAI-compatible endpoint preset, or enter the endpoint URL shown by your runtime.
 5. Leave API key empty unless your local gateway requires one.
 6. Click Fetch models and choose a served model from the model selector.
-7. Keep Request JSON mode enabled when supported. Disable it if the local runtime rejects the `response_format` request field.
+7. For OpenAI Compatible, keep Request JSON mode enabled when supported. Disable it if the local runtime rejects the `response_format` request field.
 
 Runtime notes:
 
 - LM Studio commonly serves OpenAI-compatible requests at `http://localhost:1234/v1/chat/completions`.
 - Ollama requires its OpenAI-compatible API to be available at `http://localhost:11434/v1/chat/completions`.
+- Ollama can also expose Anthropic-compatible requests at `http://localhost:11434/v1/messages`. Margin sends tools for structured output but does not force `tool_choice` for Anthropic-compatible endpoints, because some compatible runtimes accept tools but do not support forced tool selection.
 - llama.cpp server must be started with an OpenAI-compatible HTTP server enabled, commonly at `http://localhost:8080/v1/chat/completions`.
 - omlx is an Apple Silicon MLX inference server. Start it with `omlx serve` (zero-config, models from `~/.omlx/models`) or `omlx serve --model-dir /path/to/models`; the OpenAI-compatible API becomes available at `http://localhost:8000/v1/chat/completions`.
-- If Fetch models fails, confirm the local server is running, the endpoint URL ends with `/v1/chat/completions`, and the runtime exposes a compatible `/v1/models` endpoint.
+- If Fetch models fails, confirm the local server is running, the endpoint URL ends with `/v1/chat/completions` or `/v1/messages`, and the runtime exposes a compatible `/v1/models` endpoint.
 
 Local model quality, speed, context length, and JSON reliability depend on the model and runtime. Instruct models with strong multilingual ability are recommended for translation.
 
diff --git a/README.zh-TW.md b/README.zh-TW.md
index 240b860..3187284 100644
--- a/README.zh-TW.md
+++ b/README.zh-TW.md
@@ -22,8 +22,8 @@ Margin 目前仍是早期 MVP，支援 Chrome 與其他 Chromium 系瀏覽器，
 - 支援舊式 `table`、`font`，以及以 `br` 分隔文字的頁面。
 - 避開常見的非閱讀區域，例如導覽列、表單、按鈕、程式碼區塊、隱藏文字與頁面介面。
 - 使用你自行設定的 provider endpoint 與 API key。
-- 支援 OpenAI、Anthropic Claude 與 Google Gemini provider adapter。
-- 支援本機 OpenAI-compatible runtime，例如 LM Studio、Ollama、llama.cpp server 與 omlx（Apple Silicon）。
+- 支援 OpenAI、Anthropic Claude、Google Gemini 與 compatible provider adapter。
+- 支援本機 OpenAI-compatible runtime，例如 LM Studio、Ollama、llama.cpp server 與 omlx（Apple Silicon），以及 Anthropic Messages API-compatible endpoint。
 - 可從 options 頁面取得 provider 的模型列表。
 - 可選擇融入原文或醒目提示的譯文顯示樣式。
 - 可選擇在頁面顯示浮動翻譯按鈕，且只有使用者點擊後才開始翻譯。
@@ -66,13 +66,14 @@ Anthropic Claude: https://api.anthropic.com/v1/messages
 Google Gemini: https://generativelanguage.googleapis.com/v1beta/models
 ```
 
-Endpoint 欄位只會在 OpenAI Compatible / Local LLM 設定中顯示，因為這些情境才需要使用者選擇或輸入本機 endpoint。
+Endpoint 欄位只會在 compatible / Local LLM 設定中顯示，因為這些情境才需要使用者選擇或輸入本機 endpoint。
 
 Fetch models 會從目前選擇的 provider 讀取可用模型：
 
 - OpenAI: `GET /v1/models`
 - Anthropic Claude: `GET /v1/models`
 - Google Gemini: `GET /v1beta/models`
+- OpenAI Compatible / Anthropic Compatible: `GET /v1/models`
 
 取得的模型會出現在模型選單中。如果目前設定的 provider 預設模型或已儲存模型沒有出現在 provider 回傳的列表中，Margin 會保留它作為可選項目。
 
@@ -92,34 +93,42 @@ Quoted posts 預設不會翻譯，可在 options 中啟用。X 已標示為翻
 
 ## 本機 LLM
 
-Margin 透過 OpenAI Compatible provider 支援本機 LLM runtime。這個 provider 使用 OpenAI 風格的 `/v1/chat/completions` API，允許 API key 留空，並針對本機推理使用較低的預設翻譯 concurrency。
+Margin 透過 compatible provider 支援本機 LLM runtime：
 
-常見 endpoint preset：
+- OpenAI Compatible 使用 OpenAI 風格的 `/v1/chat/completions` API。
+- Anthropic Compatible 使用 Anthropic Messages 風格的 `/v1/messages` API，並透過 tool `input_schema` 取得結構化輸出。這是給相容本機或 gateway endpoint 使用的 wire-protocol 選項，不是另一個 Anthropic 官方代管服務。
+
+兩種 compatible provider 都允許 API key 留空，並針對本機推理使用較低的預設翻譯 concurrency。如果 Anthropic-compatible gateway 需要 key，Margin 會以 `Authorization: Bearer ...` 送出。
+
+常見 compatible endpoint：
 
 ```text
 LM Studio: http://localhost:1234/v1/chat/completions
 Ollama: http://localhost:11434/v1/chat/completions
 llama.cpp server: http://localhost:8080/v1/chat/completions
 omlx: http://localhost:8000/v1/chat/completions
+Generic Anthropic-compatible: http://localhost:8000/v1/messages
+Ollama Anthropic compatibility: http://localhost:11434/v1/messages
 ```
 
 使用本機 runtime：
 
 1. 啟動本機模型 server。
 2. 開啟 Margin options。
-3. 選擇 OpenAI Compatible 作為 provider。
-4. 選擇 endpoint preset，或輸入你的 runtime 顯示的 endpoint URL。
+3. 如果 endpoint 是 `/v1/chat/completions`，選擇 OpenAI Compatible；如果 endpoint 是 `/v1/messages`，選擇 Anthropic Compatible。
+4. 選擇 OpenAI-compatible endpoint preset，或輸入你的 runtime 顯示的 endpoint URL。
 5. 除非你的本機 gateway 需要 API key，否則 API key 可以留空。
 6. 點擊 Fetch models，並從模型選單中選擇 server 提供的模型。
-7. 如果 runtime 支援，建議保持 Request JSON mode 啟用。若本機 runtime 拒絕 `response_format` request 欄位，請停用此選項。
+7. 對 OpenAI Compatible 而言，如果 runtime 支援，建議保持 Request JSON mode 啟用。若本機 runtime 拒絕 `response_format` request 欄位，請停用此選項。
 
 Runtime 注意事項：
 
 - LM Studio 通常在 `http://localhost:1234/v1/chat/completions` 提供 OpenAI-compatible request。
 - Ollama 需要 OpenAI-compatible API 可在 `http://localhost:11434/v1/chat/completions` 使用。
+- Ollama 也可以在 `http://localhost:11434/v1/messages` 提供 Anthropic-compatible request。Margin 會送出 tools 以取得結構化輸出，但不會在 Anthropic-compatible endpoint 強制指定 `tool_choice`，因為部分相容 runtime 接受 tools，卻不支援 forced tool selection。
 - llama.cpp server 必須啟動 OpenAI-compatible HTTP server，常見位址為 `http://localhost:8080/v1/chat/completions`。
 - omlx 是 Apple Silicon 上的 MLX 推論 server。以 `omlx serve`（零設定，模型從 `~/.omlx/models` 載入）或 `omlx serve --model-dir /path/to/models` 啟動後，OpenAI-compatible API 預設位於 `http://localhost:8000/v1/chat/completions`。
-- 如果 Fetch models 失敗，請確認本機 server 已啟動、endpoint URL 以 `/v1/chat/completions` 結尾，且 runtime 有提供 compatible `/v1/models` endpoint。
+- 如果 Fetch models 失敗，請確認本機 server 已啟動、endpoint URL 以 `/v1/chat/completions` 或 `/v1/messages` 結尾，且 runtime 有提供 compatible `/v1/models` endpoint。
 
 本機模型的品質、速度、context length 與 JSON 穩定性，取決於模型與 runtime。建議使用具備強多語能力的 instruct model 進行翻譯。
 
diff --git a/apps/extension/src/background/providers/anthropic.test.ts b/apps/extension/src/background/providers/anthropic.test.ts
index f2a9fdf..511e680 100644
--- a/apps/extension/src/background/providers/anthropic.test.ts
+++ b/apps/extension/src/background/providers/anthropic.test.ts
@@ -148,6 +148,8 @@ describe("anthropicCompatibleProvider.translate", () => {
     expect(headers["x-api-key"]).toBeUndefined();
     expect(headers["anthropic-dangerous-direct-browser-access"]).toBeUndefined();
     expect(headers["anthropic-version"]).toBe("2023-06-01");
+    expect(calls[0].body.tool_choice).toBeUndefined();
+    expect((calls[0].body.tools as Array<{ name: string }>)[0].name).toBe("return_translations");
   });
 
   it("omits Authorization header when api key is empty", async () => {
diff --git a/apps/extension/src/background/providers/anthropic.ts b/apps/extension/src/background/providers/anthropic.ts
index d634ee7..43ae1d0 100644
--- a/apps/extension/src/background/providers/anthropic.ts
+++ b/apps/extension/src/background/providers/anthropic.ts
@@ -35,7 +35,7 @@ async function translateWithAnthropic(
   segments: TextSegment[],
   settings: ExtensionSettings
 ): Promise<TranslationResult[]> {
-  const body = {
+  const body: AnthropicRequestBody = {
     model: settings.model,
     max_tokens: 4096,
     temperature: 0,
@@ -47,9 +47,12 @@ async function translateWithAnthropic(
         input_schema: getTranslationSchema() as Tool.InputSchema
       }
     ],
-    tool_choice: { type: "tool" as const, name: TRANSLATION_TOOL_NAME },
     messages: [{ role: "user" as const, content: buildTranslationPayload(segments, settings) }]
-  } satisfies AnthropicRequestBody;
+  };
+
+  if (settings.provider === "anthropic") {
+    body.tool_choice = { type: "tool", name: TRANSLATION_TOOL_NAME };
+  }
 
   const response = await fetch(settings.providerEndpoint, {
     method: "POST",
diff --git a/apps/extension/src/content/orchestrator.test.ts b/apps/extension/src/content/orchestrator.test.ts
index d7b0af9..d345ab9 100644
--- a/apps/extension/src/content/orchestrator.test.ts
+++ b/apps/extension/src/content/orchestrator.test.ts
@@ -499,4 +499,30 @@ describe("createOrchestrator — debug state plumbing", () => {
       extensionVersion: "0.3.2"
     });
   });
+
+  it("labels Anthropic-compatible debug sessions as tool schema requests", async () => {
+    useRouter({
+      settings: {
+        ...DEFAULT_SETTINGS,
+        debugMode: true,
+        provider: "anthropic-compatible",
+        model: "local-claude",
+        providerEndpoint: "http://user:pass@localhost:8000/v1/messages?token=secret#fragment"
+      }
+    });
+
+    seedDocument(`<main><p>${SAMPLE_PARAGRAPH}</p></main>`);
+    const orchestrator = createTestOrchestrator();
+
+    await orchestrator.setEnabled(true);
+
+    expect(orchestrator.getDebugState().providerConfig).toEqual({
+      provider: "anthropic-compatible",
+      providerName: "Anthropic Compatible",
+      model: "local-claude",
+      endpoint: "http://localhost:8000/v1/messages",
+      structuredOutput: "tool input_schema",
+      extensionVersion: "0.3.2"
+    });
+  });
 });
diff --git a/apps/extension/src/content/orchestrator.ts b/apps/extension/src/content/orchestrator.ts
index e3b0bbc..0298f46 100644
--- a/apps/extension/src/content/orchestrator.ts
+++ b/apps/extension/src/content/orchestrator.ts
@@ -29,7 +29,8 @@ const PROVIDER_DISPLAY_NAMES: Record<TranslationProviderId, string> = {
   openai: "OpenAI",
   anthropic: "Anthropic Claude",
   google: "Google Gemini",
-  "openai-compatible": "OpenAI Compatible"
+  "openai-compatible": "OpenAI Compatible",
+  "anthropic-compatible": "Anthropic Compatible"
 };
 
 interface TranslationBatchResponse {
@@ -357,7 +358,7 @@ export function createOrchestrator(options: ContentOrchestratorOptions): Content
   ): string {
     if (provider === "google") return "responseJsonSchema";
     if (provider === "openai") return "json_schema";
-    if (provider === "anthropic") return "tool input_schema";
+    if (provider === "anthropic" || provider === "anthropic-compatible") return "tool input_schema";
     return settings?.openAICompatibleJsonMode ? "json_object" : "prompt only";
   }
 
diff --git a/apps/extension/src/shared/localProviders.ts b/apps/extension/src/shared/localProviders.ts
index 398ae59..3b36525 100644
--- a/apps/extension/src/shared/localProviders.ts
+++ b/apps/extension/src/shared/localProviders.ts
@@ -1,6 +1,9 @@
 import type { TranslationProviderId } from "./types";
 
-export const LOCAL_TRANSLATION_PROVIDERS = ["openai-compatible", "anthropic-compatible"] as const;
+export const LOCAL_TRANSLATION_PROVIDERS = [
+  "openai-compatible",
+  "anthropic-compatible"
+] as const satisfies readonly TranslationProviderId[];
 
 export type LocalTranslationProviderId = (typeof LOCAL_TRANSLATION_PROVIDERS)[number];
 
diff --git a/apps/extension/src/shared/migrations/versions/v0.test.ts b/apps/extension/src/shared/migrations/versions/v0.test.ts
index 642068b..7cbf38c 100644
--- a/apps/extension/src/shared/migrations/versions/v0.test.ts
+++ b/apps/extension/src/shared/migrations/versions/v0.test.ts
@@ -37,6 +37,12 @@ describe("parseV0", () => {
     expect(result.cacheMode).toBe("session");
   });
 
+  it("rejects providers introduced after the v0 snapshot", () => {
+    const result = parseV0({ provider: "anthropic-compatible" });
+
+    expect(result.provider).toBeUndefined();
+  });
+
   it("drops non-boolean values for boolean fields", () => {
     const result = parseV0({
       debugMode: "yes",
diff --git a/apps/extension/src/shared/migrations/versions/v0.ts b/apps/extension/src/shared/migrations/versions/v0.ts
index 0633417..08f5b40 100644
--- a/apps/extension/src/shared/migrations/versions/v0.ts
+++ b/apps/extension/src/shared/migrations/versions/v0.ts
@@ -11,10 +11,12 @@
  * a rewrite of this file.
  */
 
-import type { CacheMode, DisplayStyle, TranslationProviderId } from "../../types";
+import type { CacheMode, DisplayStyle } from "../../types";
+
+type TranslationProviderIdV0 = "openai" | "anthropic" | "google" | "openai-compatible";
 
 export interface ExtensionSettingsV0 {
-  provider?: TranslationProviderId;
+  provider?: TranslationProviderIdV0;
   providerEndpoint?: string;
   apiKey?: string;
   model?: string;
@@ -31,7 +33,7 @@ export interface ExtensionSettingsV0 {
   showFloatingButton?: boolean;
 }
 
-const PROVIDERS: readonly TranslationProviderId[] = ["openai", "anthropic", "google", "openai-compatible", "anthropic-compatible"];
+const PROVIDERS: readonly TranslationProviderIdV0[] = ["openai", "anthropic", "google", "openai-compatible"];
 const DISPLAY_STYLES: readonly DisplayStyle[] = ["integrated", "highlighted"];
 const CACHE_MODES: readonly CacheMode[] = ["session", "persistent", "disabled"];