fix(proxy): Anthropic connection base URL receives the caller's anthropic-beta flags

docs/releases/0.31.6.md

@@ -0,0 +1,9 @@
+# Thinker 0.31.6
+
+```bash
+docker pull tmsoftbrasil/thinker:0.31.6
+```
+
+## Mudanças
+
+- fix(proxy): the Anthropic connection's own base URL receives the caller's anthropic-beta flags

packages/backend/src/routing/proxy/__tests__/provider-client.headers.spec.ts

@@ -9,6 +9,7 @@
 // fails loudly.
 
 import { ProviderClient } from '../provider-client';
+import { buildEndpointOverride } from '../provider-endpoints';
 import { CodexSessionAffinity } from '../codex-session-affinity';
 
 const UUID_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/;
@@ -482,6 +483,47 @@ describe('ProviderClient — anthropic-beta merge', () => {
     expect(sentBeta()).toBe('structured-outputs-2025-11-13');
   });
 
+  it("forwards through the Anthropic connection's own base URL (a proxy or simulator)", async () => {
+    // Without the flags, Claude Code's beta-only fields (role "system" turns
+    // with output_config, per-turn-control) are refused upstream.
+    const customEndpoint = {
+      ...buildEndpointOverride('http://wwz:8000/anthropic', 'anthropic'),
+      requiresSsrfRevalidation: false,
+    };
+    customEndpoint.anthropicAccountOverride = true;
+    await client.forward({
+      provider: 'anthropic',
+      apiKey: 'sk-ant-key',
+      model: 'claude-sonnet-4-20250514',
+      body,
+      stream: false,
+      apiMode: 'messages',
+      clientAnthropicBeta: 'per-turn-control-2026-07-01',
+      customEndpoint,
+    });
+
+    expect(mockFetch.mock.calls[0][0]).toBe('http://wwz:8000/anthropic/v1/messages');
+    expect(sentBeta()).toBe('per-turn-control-2026-07-01');
+  });
+
+  it('does not forward beta flags to an Anthropic-format override of another provider', async () => {
+    await client.forward({
+      provider: 'minimax',
+      apiKey: 'k',
+      model: 'MiniMax-M2',
+      body,
+      stream: false,
+      apiMode: 'messages',
+      clientAnthropicBeta: 'per-turn-control-2026-07-01',
+      customEndpoint: {
+        ...buildEndpointOverride('http://proxy:8000', 'anthropic'),
+        requiresSsrfRevalidation: false,
+      },
+    });
+
+    expect(mockFetch.mock.calls[0][1].headers).not.toHaveProperty('anthropic-beta');
+  });
+
   it('does not forward beta flags on a translated (non-Messages) request', async () => {
     // A chat-completions body reaches Anthropic through the OpenAI->Anthropic
     // converters, which only understand the content blocks they were written

packages/backend/src/routing/proxy/forward-endpoint-resolver.spec.ts

@@ -366,6 +366,23 @@ describe('resolveForwardEndpoint', () => {
     expect(or.forwardModel).toBe('white-wizard/wwz-fast');
   });
 
+  it('marks the Anthropic connection override so caller beta flags still reach it', () => {
+    const out = resolveForwardEndpoint({
+      provider: 'anthropic',
+      authType: 'api_key',
+      model: 'claude-sonnet-5-5',
+      providerBaseUrl: 'http://wwz:8000/anthropic',
+    });
+    expect(out.customEndpoint?.anthropicAccountOverride).toBe(true);
+    const openai = resolveForwardEndpoint({
+      provider: 'openai',
+      authType: 'api_key',
+      model: 'gpt-4o',
+      providerBaseUrl: 'http://wwz:8000/openai',
+    });
+    expect(openai.customEndpoint?.anthropicAccountOverride).toBeUndefined();
+  });
+
   it('sets no override for a custom provider whose row is missing', () => {
     const out = resolveForwardEndpoint({
       provider: 'custom:gone',

packages/backend/src/routing/proxy/forward-endpoint-resolver.ts

@@ -168,6 +168,7 @@ export function resolveForwardEndpoint(
     // exactly as the native endpoint would have.
     forwardModel = stripModelPrefix(forwardModel, overrideKey);
     customEndpoint.allowPrivateDestination = allowsPrivateDestination(providerBaseUrlAllowsPrivate);
+    if (overrideKey === 'anthropic') customEndpoint.anthropicAccountOverride = true;
   } else if (resolveEndpointKey(provider) === 'bedrock' && isBedrockRegion(providerRegion)) {
     const bedrockEndpointKey = resolveBedrockEndpointKey(model, apiMode);
     customEndpoint = buildEndpointOverride(

packages/backend/src/routing/proxy/provider-client.ts

@@ -854,7 +854,11 @@ export class ProviderClient {
           // type would have its output silently dropped on the way back, which
           // is worse than the 400 we are fixing. Native Messages responses pass
           // through byte-for-byte, so unknown blocks survive there.
-          ctx.apiMode === 'messages' && isAnthropicHost(endpoint.baseUrl)
+          // The Anthropic connection's own base URL counts too: the operator
+          // pointed the Anthropic provider there (a proxy, a simulator), and
+          // without the flags Claude Code's beta-only fields are refused.
+          ctx.apiMode === 'messages' &&
+            (isAnthropicHost(endpoint.baseUrl) || endpoint.anthropicAccountOverride === true)
             ? ctx.clientAnthropicBeta
             : undefined,
         ),

packages/backend/src/routing/proxy/provider-endpoints.ts

@@ -66,6 +66,12 @@ export interface ProviderEndpoint {
    * private-URL policy did not allow, ADR 0006 item 7). Absent = allowed.
    */
   allowPrivateDestination?: boolean;
+  /**
+   * The Anthropic provider's own connection with an operator-set base URL
+   * (a proxy in front of Anthropic, a simulator). It is Anthropic as far as
+   * the caller's `anthropic-beta` flags go, though the host is not.
+   */
+  anthropicAccountOverride?: boolean;
   /**
    * Upper bound of one forwarded request, overriding PROVIDER_TIMEOUT_MS.
    * Set per local server, whose first call may have to load the model.

packages/thinker/package.json

@@ -1,6 +1,6 @@
 {
   "name": "thinker",
-  "version": "0.31.5",
+  "version": "0.31.6",
   "private": true,
   "description": "Canonical release version for the Thinker Docker image. This package holds no code — the real backend and frontend live in ../backend and ../frontend. See README.md for details."
 }