diff --git a/packages/vscode/src/DOCUMENTATION.md b/packages/vscode/src/DOCUMENTATION.md
index 5b758856..7aefa3ab 100644
--- a/packages/vscode/src/DOCUMENTATION.md
+++ b/packages/vscode/src/DOCUMENTATION.md
@@ -72,7 +72,7 @@ The webview build emits each worker as one self-contained file. VS Code webviews
   - Includes session activity snapshot bridge handler used by webview parity routes (`/api/session-activity`).
   - Includes Zen utility model parity handler used by shared notification settings (`/api/zen/models`).
   - Owns managed OpenCode upgrade status and mutation handlers, including capability reporting, upgrade serialization, and process restart after a successful upgrade.
-  - Provider handlers cover source lookup, disconnect (`DELETE /api/provider/:id/auth`), and custom provider upsert (`PUT /api/provider`; create/update OpenAI-compatible config with explicit `scope` for user/project/custom layers; requires `env` or stored auth; secrets via OpenCode auth API). Updates preserve existing provider, option, and retained-model fields that the form does not manage while honoring explicit model, header, and env removal. Legacy `providers` entries migrate to the canonical `provider` key when edited.
+  - Provider handlers cover source lookup, disconnect (`DELETE /api/provider/:id/auth`), and custom provider upsert (`PUT /api/provider`; create/update OpenAI Chat Completions, OpenAI Responses, or Anthropic Messages config with explicit `scope` for user/project/custom layers; requires `env` or stored auth; secrets via OpenCode auth API). Updates preserve existing provider, option, and retained-model fields that the form does not manage while honoring explicit model, header, and env removal. Legacy `providers` entries migrate to the canonical `provider` key when edited.
   - Quota handlers keep managed exe.dev, Ollama Cloud, and Cursor credentials in the extension data directory with the same private-file contract as the web runtime. exe.dev uses one command-scoped usage token for the aggregate billing shared by every `exe-*` model provider.
 
 - `opencode-upgrade-runtime.ts`
diff --git a/packages/vscode/src/opencodeConfig.providers.test.ts b/packages/vscode/src/opencodeConfig.providers.test.ts
index 1da73ede..8a4ac246 100644
--- a/packages/vscode/src/opencodeConfig.providers.test.ts
+++ b/packages/vscode/src/opencodeConfig.providers.test.ts
@@ -72,6 +72,33 @@ describe('custom provider config persistence (VS Code parity)', () => {
     }).ok, true);
   });
 
+  test('accepts supported protocol adapters and rejects arbitrary npm packages', () => {
+    for (const npm of ['@ai-sdk/openai-compatible', '@ai-sdk/openai', '@ai-sdk/anthropic']) {
+      const result = validateCustomProviderConfig('ok', {
+        name: 'X',
+        npm,
+        env: ['MY_KEY'],
+        options: { baseURL: 'https://api.example.com/v1' },
+        models: { m: { name: 'M' } },
+      });
+      assert.equal(result.ok, true);
+      if (result.ok) assert.equal(result.value.config.npm, npm);
+    }
+
+    const unsupported = validateCustomProviderConfig('ok', {
+      name: 'X',
+      npm: 'untrusted-provider-package',
+      env: ['MY_KEY'],
+      options: { baseURL: 'https://api.example.com/v1' },
+      models: { m: { name: 'M' } },
+    });
+    assert.equal(unsupported.ok, false);
+    assert.equal(
+      unsupported.error,
+      'Custom providers must use @ai-sdk/openai-compatible, @ai-sdk/openai, or @ai-sdk/anthropic',
+    );
+  });
+
   test('upsertProviderConfig writes and round-trips project config', () => {
     const result = upsertProviderConfig('campus-llm', {
       name: 'Campus LLM',
@@ -109,6 +136,23 @@ describe('custom provider config persistence (VS Code parity)', () => {
     assert.equal(sources.project.path, result.path);
   });
 
+  test('round-trips non-default protocol adapters through project config', () => {
+    for (const [providerId, npm] of [
+      ['responses-provider', '@ai-sdk/openai'],
+      ['anthropic-provider', '@ai-sdk/anthropic'],
+    ]) {
+      const result = upsertProviderConfig(providerId, {
+        name: providerId,
+        npm,
+        env: ['PROVIDER_KEY'],
+        options: { baseURL: 'https://api.example.com/v1' },
+        models: { model: { name: 'Model' } },
+      }, projectDir, 'project');
+      assert.equal(result.config.npm, npm);
+      assert.equal(readJson(result.path).provider[providerId].npm, npm);
+    }
+  });
+
   test('upsertProviderConfig updates existing entry and clears disabled_providers', () => {
     const configPath = path.join(projectDir, 'opencode.json');
     writeJson(configPath, {
diff --git a/packages/vscode/src/opencodeConfig.ts b/packages/vscode/src/opencodeConfig.ts
index 341dc87f..629aecaa 100644
--- a/packages/vscode/src/opencodeConfig.ts
+++ b/packages/vscode/src/opencodeConfig.ts
@@ -2266,6 +2266,11 @@ export const removeProviderConfig = (providerId: string, workingDirectory?: stri
 const PROVIDER_ID_PATTERN = /^[a-z0-9][a-z0-9-_]*$/;
 const BASE_URL_PATTERN = /^https?:\/\//;
 const OPENAI_COMPATIBLE_NPM = '@ai-sdk/openai-compatible';
+const CUSTOM_PROVIDER_NPM_PACKAGES = new Set([
+  OPENAI_COMPATIBLE_NPM,
+  '@ai-sdk/openai',
+  '@ai-sdk/anthropic',
+]);
 
 type JsonValue = string | number | boolean | null | JsonObject | JsonValue[];
 type JsonObject = { [key: string]: JsonValue };
@@ -2301,8 +2306,11 @@ export const validateCustomProviderConfig = (
   }
 
   const npm = typeof config.npm === 'string' ? config.npm.trim() : OPENAI_COMPATIBLE_NPM;
-  if (npm !== OPENAI_COMPATIBLE_NPM) {
-    return { ok: false as const, error: `Custom providers must use npm package ${OPENAI_COMPATIBLE_NPM}` };
+  if (!CUSTOM_PROVIDER_NPM_PACKAGES.has(npm)) {
+    return {
+      ok: false as const,
+      error: 'Custom providers must use @ai-sdk/openai-compatible, @ai-sdk/openai, or @ai-sdk/anthropic',
+    };
   }
 
   const optionsBlock = isPlainObject(config.options) ? config.options : null;
@@ -2340,7 +2348,7 @@ export const validateCustomProviderConfig = (
   }
 
   const normalized: NormalizedCustomProviderConfig = {
-    npm: OPENAI_COMPATIBLE_NPM,
+    npm,
     name,
     options: {
       baseURL,