diff --git a/src/cliproxy/executor/__tests__/proxy-chain-builder.test.ts b/src/cliproxy/executor/__tests__/proxy-chain-builder.test.ts
new file mode 100644
index 00000000..a39be32e
--- /dev/null
+++ b/src/cliproxy/executor/__tests__/proxy-chain-builder.test.ts
@@ -0,0 +1,273 @@
+/**
+ * Unit tests for proxy-chain-builder.ts (Phase 07)
+ *
+ * Mocking strategy: proxy constructors are injected via the _ToolSanitizationProxy
+ * and _CodexReasoningProxy fields on ProxyChainContext (dependency-injection escape
+ * hatch added for testability).  This avoids Bun module-cache limitations with
+ * mock.module / jest.mock and never spins up real HTTP servers.
+ *
+ * Tests cover:
+ * - Tool sanitization proxy started when ANTHROPIC_BASE_URL is set
+ * - Tool sanitization proxy skipped when ANTHROPIC_BASE_URL is absent
+ * - Tool sanitization proxy start failure swallowed (null returned, verbose warn)
+ * - Codex reasoning proxy started for single-provider codex
+ * - Codex reasoning proxy skipped for composite codex (cfg.isComposite true)
+ * - Codex reasoning proxy skipped for non-codex provider
+ * - Codex reasoning proxy uses post-sanitization URL when tool-san is active
+ * - Codex reasoning proxy start failure swallowed (null returned)
+ * - All results null when ANTHROPIC_BASE_URL absent
+ */
+
+import { describe, expect, it, jest, beforeEach } from 'bun:test';
+import { buildProxyChain } from '../proxy-chain-builder';
+import type { ProxyChainContext } from '../proxy-chain-builder';
+import type { ToolSanitizationProxy } from '../../proxy/tool-sanitization-proxy';
+import type { CodexReasoningProxy } from '../../ai-providers/codex-reasoning-proxy';
+
+// ── Stub factory ──────────────────────────────────────────────────────────────
+
+type ProxyStub = { start: jest.Mock; stop: jest.Mock; _port?: number };
+
+function makeStubCtor(resolvePort: number | (() => Promise<number> | number)): {
+  ctor: jest.Mock;
+  instance: ProxyStub;
+} {
+  const instance: ProxyStub = {
+    start: jest
+      .fn()
+      .mockImplementation(
+        typeof resolvePort === 'function' ? resolvePort : () => Promise.resolve(resolvePort)
+      ),
+    stop: jest.fn(),
+  };
+  const ctor = jest.fn().mockReturnValue(instance);
+  return { ctor, instance };
+}
+
+function makeFailCtor(message: string): { ctor: jest.Mock; instance: ProxyStub } {
+  const instance: ProxyStub = {
+    start: jest.fn().mockRejectedValue(new Error(message)),
+    stop: jest.fn(),
+  };
+  const ctor = jest.fn().mockReturnValue(instance);
+  return { ctor, instance };
+}
+
+// ── Context helpers ───────────────────────────────────────────────────────────
+
+function makeThinkingCfg() {
+  return { mode: 'auto' as const, override: undefined };
+}
+
+function makeProxyConfig() {
+  return {
+    mode: 'local' as const,
+    port: 8317,
+    protocol: 'http' as const,
+    fallbackEnabled: false,
+    autoStartLocal: true,
+    remoteOnly: false,
+    forceLocal: false,
+  };
+}
+
+function makeCfg(overrides: Partial<{ isComposite: boolean }> = {}) {
+  return { port: 8317, timeout: 5000, verbose: false, pollInterval: 100, ...overrides };
+}
+
+// Stub ctors shared across tests, reset in beforeEach
+let defaultToolSan: ReturnType<typeof makeStubCtor>;
+let defaultCodex: ReturnType<typeof makeStubCtor>;
+
+beforeEach(() => {
+  defaultToolSan = makeStubCtor(19001);
+  defaultCodex = makeStubCtor(19002);
+});
+
+function baseCtx(overrides: Partial<ProxyChainContext> = {}): ProxyChainContext {
+  return {
+    provider: 'gemini',
+    useRemoteProxy: false,
+    proxyConfig: makeProxyConfig(),
+    cfg: makeCfg(),
+    initialEnvVars: { ANTHROPIC_BASE_URL: 'http://127.0.0.1:8317' },
+    thinkingOverride: undefined,
+    thinkingCfg: makeThinkingCfg(),
+    verbose: false,
+    log: () => {},
+    _ToolSanitizationProxy: defaultToolSan.ctor as unknown as new (
+      cfg: object
+    ) => ToolSanitizationProxy,
+    _CodexReasoningProxy: defaultCodex.ctor as unknown as new (cfg: object) => CodexReasoningProxy,
+    ...overrides,
+  };
+}
+
+// ── Tool sanitization: started when ANTHROPIC_BASE_URL set ───────────────────
+
+describe('buildProxyChain — tool sanitization: started when ANTHROPIC_BASE_URL set', () => {
+  it('starts proxy and returns instance + port', async () => {
+    const { ctor, instance } = makeStubCtor(13001);
+
+    const result = await buildProxyChain(baseCtx({ _ToolSanitizationProxy: ctor as never }));
+
+    expect(ctor).toHaveBeenCalledTimes(1);
+    expect(result.toolSanitizationProxy).toBe(instance);
+    expect(result.toolSanitizationPort).toBe(13001);
+  });
+});
+
+// ── Tool sanitization: skipped when ANTHROPIC_BASE_URL absent ────────────────
+
+describe('buildProxyChain — tool sanitization: skipped when no ANTHROPIC_BASE_URL', () => {
+  it('returns null proxy and port without constructing', async () => {
+    const { ctor } = makeStubCtor(13001);
+
+    const result = await buildProxyChain(
+      baseCtx({ initialEnvVars: {}, _ToolSanitizationProxy: ctor as never })
+    );
+
+    expect(ctor).not.toHaveBeenCalled();
+    expect(result.toolSanitizationProxy).toBeNull();
+    expect(result.toolSanitizationPort).toBeNull();
+  });
+});
+
+// ── Tool sanitization: start failure swallowed ────────────────────────────────
+
+describe('buildProxyChain — tool sanitization: start failure swallowed', () => {
+  it('returns null and emits verbose warn without throwing', async () => {
+    const { ctor } = makeFailCtor('port in use');
+    const warnSpy = jest.spyOn(console, 'error').mockImplementation(() => {});
+
+    const result = await buildProxyChain(
+      baseCtx({ verbose: true, _ToolSanitizationProxy: ctor as never })
+    );
+
+    expect(result.toolSanitizationProxy).toBeNull();
+    expect(result.toolSanitizationPort).toBeNull();
+    expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('port in use'));
+    warnSpy.mockRestore();
+  });
+});
+
+// ── Codex reasoning: started for single-provider codex ───────────────────────
+
+describe('buildProxyChain — codex reasoning: started for single-provider codex', () => {
+  it('starts codex proxy and returns instance + port', async () => {
+    const sanCtorPair = makeStubCtor(13010);
+    const codexCtorPair = makeStubCtor(13011);
+
+    const result = await buildProxyChain(
+      baseCtx({
+        provider: 'codex',
+        cfg: makeCfg({ isComposite: false }),
+        _ToolSanitizationProxy: sanCtorPair.ctor as never,
+        _CodexReasoningProxy: codexCtorPair.ctor as never,
+      })
+    );
+
+    expect(codexCtorPair.ctor).toHaveBeenCalledTimes(1);
+    expect(result.codexReasoningProxy).toBe(codexCtorPair.instance);
+    expect(result.codexReasoningPort).toBe(13011);
+  });
+});
+
+// ── Codex reasoning: skipped for composite codex ─────────────────────────────
+
+describe('buildProxyChain — codex reasoning: skipped for composite codex', () => {
+  it('does not construct CodexReasoningProxy when cfg.isComposite is true', async () => {
+    const { ctor } = makeStubCtor(13020);
+
+    const result = await buildProxyChain(
+      baseCtx({
+        provider: 'codex',
+        cfg: makeCfg({ isComposite: true }),
+        _CodexReasoningProxy: ctor as never,
+      })
+    );
+
+    expect(ctor).not.toHaveBeenCalled();
+    expect(result.codexReasoningProxy).toBeNull();
+    expect(result.codexReasoningPort).toBeNull();
+  });
+});
+
+// ── Codex reasoning: skipped for non-codex provider ──────────────────────────
+
+describe('buildProxyChain — codex reasoning: skipped for non-codex provider', () => {
+  it('does not construct CodexReasoningProxy for gemini', async () => {
+    const { ctor } = makeStubCtor(13030);
+
+    await buildProxyChain(baseCtx({ provider: 'gemini', _CodexReasoningProxy: ctor as never }));
+
+    expect(ctor).not.toHaveBeenCalled();
+  });
+});
+
+// ── Codex reasoning: uses post-sanitization URL ───────────────────────────────
+
+describe('buildProxyChain — codex reasoning: uses post-sanitization base URL', () => {
+  it('passes http://127.0.0.1:<sanPort> as upstreamBaseUrl', async () => {
+    const sanCtorPair = makeStubCtor(13040);
+    const codexCtorPair = makeStubCtor(13041);
+
+    await buildProxyChain(
+      baseCtx({
+        provider: 'codex',
+        cfg: makeCfg({ isComposite: false }),
+        _ToolSanitizationProxy: sanCtorPair.ctor as never,
+        _CodexReasoningProxy: codexCtorPair.ctor as never,
+      })
+    );
+
+    expect(codexCtorPair.ctor).toHaveBeenCalledWith(
+      expect.objectContaining({ upstreamBaseUrl: 'http://127.0.0.1:13040' })
+    );
+  });
+});
+
+// ── Codex reasoning: start failure swallowed ─────────────────────────────────
+
+describe('buildProxyChain — codex reasoning: start failure swallowed', () => {
+  it('returns null codex proxy/port without throwing', async () => {
+    const sanCtorPair = makeStubCtor(13050);
+    const { ctor: codexFailCtor } = makeFailCtor('bind failed');
+
+    const result = await buildProxyChain(
+      baseCtx({
+        provider: 'codex',
+        cfg: makeCfg({ isComposite: false }),
+        _ToolSanitizationProxy: sanCtorPair.ctor as never,
+        _CodexReasoningProxy: codexFailCtor as never,
+      })
+    );
+
+    expect(result.codexReasoningProxy).toBeNull();
+    expect(result.codexReasoningPort).toBeNull();
+  });
+});
+
+// ── All results null when no ANTHROPIC_BASE_URL ───────────────────────────────
+
+describe('buildProxyChain — all results null when no ANTHROPIC_BASE_URL', () => {
+  it('returns four nulls for gemini without base URL', async () => {
+    const sanCtor = jest.fn();
+    const codexCtor = jest.fn();
+
+    const result = await buildProxyChain(
+      baseCtx({
+        initialEnvVars: {},
+        _ToolSanitizationProxy: sanCtor as never,
+        _CodexReasoningProxy: codexCtor as never,
+      })
+    );
+
+    expect(sanCtor).not.toHaveBeenCalled();
+    expect(codexCtor).not.toHaveBeenCalled();
+    expect(result.toolSanitizationProxy).toBeNull();
+    expect(result.toolSanitizationPort).toBeNull();
+    expect(result.codexReasoningProxy).toBeNull();
+    expect(result.codexReasoningPort).toBeNull();
+  });
+});
diff --git a/src/cliproxy/executor/index.ts b/src/cliproxy/executor/index.ts
index df8ebdb2..68b8fc39 100644
--- a/src/cliproxy/executor/index.ts
+++ b/src/cliproxy/executor/index.ts
@@ -13,9 +13,7 @@
 import { spawn, ChildProcess } from 'child_process';
 import * as fs from 'fs';
 import * as os from 'os';
-import * as path from 'path';
 import { fail, info, warn } from '../../utils/ui';
-import { getCcsDir } from '../../utils/config-manager';
 import { escapeShellArg, getWindowsEscapedCommandShell } from '../../utils/shell-executor';
 import {
   generateConfig,
@@ -79,11 +77,11 @@ import {
 import {
   buildThinkingStartupStatus,
   resolveRuntimeThinkingOverride,
-  shouldDisableCodexReasoning,
 } from './thinking-override-resolver';
 import { shouldStartHttpsTunnel } from './https-tunnel-policy';
 import { filterCcsFlags, parseExecutorFlags, validateFlagCombinations } from './arg-parser';
 import { resolveExecutorProxy } from './proxy-resolver';
+import { buildProxyChain } from './proxy-chain-builder';
 
 /** Local alias so internal call sites need no change */
 const resolveRuntimeQuotaMonitorProviders = _resolveRuntimeQuotaMonitorProviders;
@@ -365,7 +363,7 @@ export async function execClaudeWithCLIProxy(
     }
   }
 
-  // 8. Setup HTTPS tunnel if needed
+  // 8. Setup HTTPS tunnel if needed (tunnelPort used by imageAnalysisProxyTarget below)
   let httpsTunnel: HttpsTunnelProxy | null = null;
   let tunnelPort: number | null = null;
 
@@ -435,9 +433,11 @@ export async function execClaudeWithCLIProxy(
     ? 'ImageAnalysis MCP provisioning failed. This session will use compatibility fallback when available.'
     : imageAnalysisResolution.warning;
 
-  // 9. Setup tool sanitization proxy
+  // 9. Resolve config dir + browser runtime (needed before proxy chain)
   let toolSanitizationProxy: ToolSanitizationProxy | null = null;
   let toolSanitizationPort: number | null = null;
+  let codexReasoningProxy: CodexReasoningProxy | null = null;
+  let codexReasoningPort: number | null = null;
   let inheritedClaudeConfigDir = cfg.claudeConfigDir;
 
   if (!inheritedClaudeConfigDir && cfg.profileName) {
@@ -488,74 +488,19 @@ export async function execClaudeWithCLIProxy(
     imageAnalysisEnv,
   });
 
-  if (initialEnvVars.ANTHROPIC_BASE_URL) {
-    try {
-      toolSanitizationProxy = new ToolSanitizationProxy({
-        upstreamBaseUrl: initialEnvVars.ANTHROPIC_BASE_URL,
-        verbose,
-        warnOnSanitize: true,
-        allowSelfSigned: useRemoteProxy ? (proxyConfig.allowSelfSigned ?? false) : false,
-      });
-      toolSanitizationPort = await toolSanitizationProxy.start();
-      log(`Tool sanitization proxy active on port ${toolSanitizationPort}`);
-    } catch (error) {
-      const err = error as Error;
-      toolSanitizationProxy = null;
-      toolSanitizationPort = null;
-      if (verbose) {
-        console.error(warn(`Tool sanitization proxy disabled: ${err.message}`));
-      }
-    }
-  }
-
-  const postSanitizationBaseUrl = toolSanitizationPort
-    ? `http://127.0.0.1:${toolSanitizationPort}`
-    : initialEnvVars.ANTHROPIC_BASE_URL;
-
-  // 10. Setup Codex reasoning proxy (single-provider Codex only)
-  let codexReasoningProxy: CodexReasoningProxy | null = null;
-  let codexReasoningPort: number | null = null;
-
-  // Composite variants require root model-routed endpoints, never provider-pinned codex endpoints.
-  if (provider === 'codex' && !cfg.isComposite) {
-    if (!postSanitizationBaseUrl) {
-      log('ANTHROPIC_BASE_URL not set for Codex, reasoning proxy disabled');
-    } else {
-      try {
-        const traceEnabled =
-          process.env.CCS_CODEX_REASONING_TRACE === '1' ||
-          process.env.CCS_CODEX_REASONING_TRACE === 'true';
-        const stripPathPrefix = useRemoteProxy ? '/api/provider/codex' : undefined;
-        const codexThinkingOff = shouldDisableCodexReasoning(thinkingCfg, thinkingOverride);
-        codexReasoningProxy = new CodexReasoningProxy({
-          upstreamBaseUrl: postSanitizationBaseUrl,
-          verbose,
-          defaultEffort: 'medium',
-          disableEffort: codexThinkingOff,
-          traceFilePath: traceEnabled ? path.join(getCcsDir(), 'codex-reasoning-proxy.log') : '',
-          allowSelfSigned: useRemoteProxy ? (proxyConfig.allowSelfSigned ?? false) : false,
-          modelMap: {
-            defaultModel: initialEnvVars.ANTHROPIC_MODEL,
-            opusModel: initialEnvVars.ANTHROPIC_DEFAULT_OPUS_MODEL,
-            sonnetModel: initialEnvVars.ANTHROPIC_DEFAULT_SONNET_MODEL,
-            haikuModel: initialEnvVars.ANTHROPIC_DEFAULT_HAIKU_MODEL,
-          },
-          stripPathPrefix,
-        });
-        codexReasoningPort = await codexReasoningProxy.start();
-        log(
-          `Codex reasoning proxy active: http://127.0.0.1:${codexReasoningPort}/api/provider/codex`
-        );
-      } catch (error) {
-        const err = error as Error;
-        codexReasoningProxy = null;
-        codexReasoningPort = null;
-        if (verbose) {
-          console.error(warn(`Codex reasoning proxy disabled: ${err.message}`));
-        }
-      }
-    }
-  }
+  // 9b. Build env-dependent proxy chain (tool-sanitization + codex-reasoning)
+  ({ toolSanitizationProxy, toolSanitizationPort, codexReasoningProxy, codexReasoningPort } =
+    await buildProxyChain({
+      provider,
+      useRemoteProxy,
+      proxyConfig,
+      cfg,
+      initialEnvVars,
+      thinkingOverride,
+      thinkingCfg,
+      verbose,
+      log,
+    }));
 
   // 11. Build final environment with all proxy chains
   const env = buildClaudeEnvironment({
diff --git a/src/cliproxy/executor/proxy-chain-builder.ts b/src/cliproxy/executor/proxy-chain-builder.ts
new file mode 100644
index 00000000..98a45b8e
--- /dev/null
+++ b/src/cliproxy/executor/proxy-chain-builder.ts
@@ -0,0 +1,185 @@
+/**
+ * Proxy Chain Builder (Concern F — tool-sanitization + codex-reasoning layers)
+ *
+ * Orchestrates the two env-dependent proxy layers that sit between the
+ * Claude CLI process and the upstream CLIProxy / remote endpoint:
+ *
+ *   1. ToolSanitizationProxy — wraps ANTHROPIC_BASE_URL to sanitize tool names/schemas
+ *   2. CodexReasoningProxy   — only for single-provider codex, wraps tool-san URL
+ *
+ * Placement in the execution sequence
+ * ─────────────────────────────────────
+ * The HTTPS tunnel (HttpsTunnelProxy) is started BEFORE this function is called,
+ * because its tunnelPort is needed by both imageAnalysisResolution and the
+ * first-pass buildClaudeEnvironment.  This function receives the result of that
+ * first-pass env as `initialEnvVars`, from which it extracts ANTHROPIC_BASE_URL
+ * to wire up the tool-sanitization proxy.
+ *
+ * Lifecycle: proxies are started (spawned) but NOT stopped here.  The caller
+ * is responsible for registering cleanup handlers (setupCleanupHandlers).
+ */
+
+import * as path from 'path';
+import { warn } from '../../utils/ui';
+import { getCcsDir } from '../../utils/config-manager';
+import {
+  ToolSanitizationProxy,
+  type ToolSanitizationProxyConfig,
+} from '../proxy/tool-sanitization-proxy';
+import {
+  CodexReasoningProxy,
+  type CodexReasoningProxyConfig,
+} from '../ai-providers/codex-reasoning-proxy';
+import { shouldDisableCodexReasoning } from './thinking-override-resolver';
+import type { CLIProxyProvider, ExecutorConfig, ResolvedProxyConfig } from '../types';
+import type { ThinkingConfig } from '../../config/unified-config-types';
+
+// ── Proxy constructor types (for dependency injection in tests) ───────────────
+
+type ToolSanitizationProxyCtor = new (config: ToolSanitizationProxyConfig) => ToolSanitizationProxy;
+type CodexReasoningProxyCtor = new (config: CodexReasoningProxyConfig) => CodexReasoningProxy;
+
+// ── Public types ──────────────────────────────────────────────────────────────
+
+export interface ProxyChainContext {
+  /** Provider being executed */
+  provider: CLIProxyProvider;
+  /** True when routing to a remote proxy host */
+  useRemoteProxy: boolean;
+  /** Resolved proxy configuration (host, port, protocol, auth, …) */
+  proxyConfig: ResolvedProxyConfig;
+  /** Executor configuration */
+  cfg: ExecutorConfig;
+  /**
+   * Initial environment from first-pass buildClaudeEnvironment.
+   * ANTHROPIC_BASE_URL and ANTHROPIC_MODEL* keys are consumed here.
+   */
+  initialEnvVars: Partial<Record<string, string>>;
+  /** Thinking mode override (value or undefined for default) */
+  thinkingOverride: string | number | undefined;
+  /** Thinking configuration from unified config */
+  thinkingCfg: ThinkingConfig;
+  verbose: boolean;
+  log: (msg: string) => void;
+  /**
+   * Optional constructor overrides for unit testing.
+   * Production code omits these; tests inject stubs to avoid real HTTP servers.
+   */
+  _ToolSanitizationProxy?: ToolSanitizationProxyCtor;
+  _CodexReasoningProxy?: CodexReasoningProxyCtor;
+}
+
+export interface ProxyChainResult {
+  toolSanitizationProxy: ToolSanitizationProxy | null;
+  toolSanitizationPort: number | null;
+  codexReasoningProxy: CodexReasoningProxy | null;
+  codexReasoningPort: number | null;
+}
+
+// ── Implementation ────────────────────────────────────────────────────────────
+
+/**
+ * Build and start the two env-dependent proxy layers (tool-sanitization and
+ * codex-reasoning).  Each layer is started independently; a failed start is
+ * swallowed with a verbose warning so the session can continue degraded.
+ *
+ * Note: HttpsTunnelProxy is started inline in the orchestrator (index.ts)
+ * before this function is called, because tunnelPort is required for
+ * imageAnalysisResolution and the first-pass buildClaudeEnvironment.
+ */
+export async function buildProxyChain(context: ProxyChainContext): Promise<ProxyChainResult> {
+  const {
+    provider,
+    useRemoteProxy,
+    proxyConfig,
+    cfg,
+    initialEnvVars,
+    thinkingOverride,
+    thinkingCfg,
+    verbose,
+    log,
+    // Allow test injection of proxy constructors so tests never spin up real servers
+    _ToolSanitizationProxy: ToolSanitizationProxyImpl = ToolSanitizationProxy,
+    _CodexReasoningProxy: CodexReasoningProxyImpl = CodexReasoningProxy,
+  } = context;
+
+  // ── Step 1: Tool sanitization proxy ────────────────────────────────────────
+  let toolSanitizationProxy: ToolSanitizationProxy | null = null;
+  let toolSanitizationPort: number | null = null;
+
+  if (initialEnvVars.ANTHROPIC_BASE_URL) {
+    try {
+      toolSanitizationProxy = new ToolSanitizationProxyImpl({
+        upstreamBaseUrl: initialEnvVars.ANTHROPIC_BASE_URL,
+        verbose,
+        warnOnSanitize: true,
+        allowSelfSigned: useRemoteProxy ? (proxyConfig.allowSelfSigned ?? false) : false,
+      });
+      toolSanitizationPort = await toolSanitizationProxy.start();
+      log(`Tool sanitization proxy active on port ${toolSanitizationPort}`);
+    } catch (error) {
+      const err = error as Error;
+      toolSanitizationProxy = null;
+      toolSanitizationPort = null;
+      if (verbose) {
+        console.error(warn(`Tool sanitization proxy disabled: ${err.message}`));
+      }
+    }
+  }
+
+  // ── Step 2: Codex reasoning proxy ──────────────────────────────────────────
+  let codexReasoningProxy: CodexReasoningProxy | null = null;
+  let codexReasoningPort: number | null = null;
+
+  // Composite variants require root model-routed endpoints, never provider-pinned codex endpoints.
+  if (provider === 'codex' && !cfg.isComposite) {
+    const postSanitizationBaseUrl = toolSanitizationPort
+      ? `http://127.0.0.1:${toolSanitizationPort}`
+      : initialEnvVars.ANTHROPIC_BASE_URL;
+
+    if (!postSanitizationBaseUrl) {
+      log('ANTHROPIC_BASE_URL not set for Codex, reasoning proxy disabled');
+    } else {
+      try {
+        const traceEnabled =
+          process.env.CCS_CODEX_REASONING_TRACE === '1' ||
+          process.env.CCS_CODEX_REASONING_TRACE === 'true';
+        const stripPathPrefix = useRemoteProxy ? '/api/provider/codex' : undefined;
+        const codexThinkingOff = shouldDisableCodexReasoning(thinkingCfg, thinkingOverride);
+        codexReasoningProxy = new CodexReasoningProxyImpl({
+          upstreamBaseUrl: postSanitizationBaseUrl,
+          verbose,
+          defaultEffort: 'medium',
+          disableEffort: codexThinkingOff,
+          traceFilePath: traceEnabled ? path.join(getCcsDir(), 'codex-reasoning-proxy.log') : '',
+          allowSelfSigned: useRemoteProxy ? (proxyConfig.allowSelfSigned ?? false) : false,
+          modelMap: {
+            defaultModel: initialEnvVars.ANTHROPIC_MODEL,
+            opusModel: initialEnvVars.ANTHROPIC_DEFAULT_OPUS_MODEL,
+            sonnetModel: initialEnvVars.ANTHROPIC_DEFAULT_SONNET_MODEL,
+            haikuModel: initialEnvVars.ANTHROPIC_DEFAULT_HAIKU_MODEL,
+          },
+          stripPathPrefix,
+        });
+        codexReasoningPort = await codexReasoningProxy.start();
+        log(
+          `Codex reasoning proxy active: http://127.0.0.1:${codexReasoningPort}/api/provider/codex`
+        );
+      } catch (error) {
+        const err = error as Error;
+        codexReasoningProxy = null;
+        codexReasoningPort = null;
+        if (verbose) {
+          console.error(warn(`Codex reasoning proxy disabled: ${err.message}`));
+        }
+      }
+    }
+  }
+
+  return {
+    toolSanitizationProxy,
+    toolSanitizationPort,
+    codexReasoningProxy,
+    codexReasoningPort,
+  };
+}