fix(codex-proxy): security hardening and edge case fixes

- Fix path traversal in trace() via safe dir validation
- Add RFC 7230 hop-by-hop header filtering
- Fix isRecord() to exclude arrays
- Add req.destroy() on oversized body rejection
- Add missing ANTHROPIC_BASE_URL warning for Codex
- Use cwd() fallback when HOME undefined
- Add 4 edge case unit tests

src/cliproxy/cliproxy-executor.ts

@@ -712,7 +712,10 @@ export async function execClaudeWithCLIProxy(
   // - Unknown → medium
   let codexReasoningProxy: CodexReasoningProxy | null = null;
   let codexReasoningPort: number | null = null;
-  if (provider === 'codex' && envVars.ANTHROPIC_BASE_URL) {
+  if (provider === 'codex') {
+    if (!envVars.ANTHROPIC_BASE_URL) {
+      log('ANTHROPIC_BASE_URL not set for Codex, reasoning proxy disabled');
+    } else {
       try {
         const traceEnabled =
           process.env.CCS_CODEX_REASONING_TRACE === '1' ||
@@ -722,7 +725,7 @@ export async function execClaudeWithCLIProxy(
           verbose,
           defaultEffort: 'medium',
           traceFilePath: traceEnabled
-          ? `${process.env.HOME || ''}/.ccs/codex-reasoning-proxy.log`
+            ? `${process.env.HOME || process.cwd()}/.ccs/codex-reasoning-proxy.log`
             : '',
           modelMap: {
             defaultModel: envVars.ANTHROPIC_MODEL,
@@ -744,6 +747,7 @@ export async function execClaudeWithCLIProxy(
         }
       }
     }
+  }
 
   const effectiveEnvVars =
     codexReasoningProxy && codexReasoningPort

src/cliproxy/codex-reasoning-proxy.ts

@@ -24,7 +24,7 @@ function isNonEmptyString(value: unknown): value is string {
 }
 
 function isRecord(value: unknown): value is Record<string, unknown> {
-  return typeof value === 'object' && value !== null;
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
 }
 
 function parseModelEffortSuffix(
@@ -141,13 +141,22 @@ export class CodexReasoningProxy {
     if (!this.config.traceFilePath) return;
     try {
       // Intentionally best-effort: tracing must never break requests.
-
       const fs = require('fs') as typeof import('fs');
+      const pathMod = require('path') as typeof import('path');
 
-      const path = require('path') as typeof import('path');
+      // Security: validate trace path against safe directories to prevent path traversal
-      const dir = path.dirname(this.config.traceFilePath);
+      const resolvedPath = pathMod.resolve(this.config.traceFilePath);
+      const home = process.env.HOME || process.env.USERPROFILE || '';
+      const safeDirs = ['/tmp/', '/var/log/', home ? `${home}/.ccs/` : ''];
+      const isSafe = safeDirs.some((base) => base && resolvedPath.startsWith(base));
+      if (!isSafe) {
+        this.log(`[SECURITY] Trace path rejected (outside allowed dirs): ${resolvedPath}`);
+        return;
+      }
+
+      const dir = pathMod.dirname(resolvedPath);
       fs.mkdirSync(dir, { recursive: true });
-      fs.appendFileSync(this.config.traceFilePath, line + '\n');
+      fs.appendFileSync(resolvedPath, line + '\n');
     } catch {
       // ignore
     }
@@ -198,6 +207,7 @@ export class CodexReasoningProxy {
       req.on('data', (chunk: Buffer) => {
         total += chunk.length;
         if (total > maxSize) {
+          req.destroy(); // Signal client to stop sending
           reject(new Error('Request body too large (max 10MB)'));
           return;
         }
@@ -293,10 +303,24 @@ export class CodexReasoningProxy {
   ): http.OutgoingHttpHeaders {
     const headers: http.OutgoingHttpHeaders = {};
 
+    // RFC 7230 hop-by-hop headers that should not be forwarded
+    const hopByHop = new Set([
+      'host',
+      'content-length',
+      'connection',
+      'transfer-encoding',
+      'keep-alive',
+      'proxy-authenticate',
+      'proxy-authorization',
+      'te',
+      'trailer',
+      'upgrade',
+    ]);
+
     for (const [key, value] of Object.entries(originalHeaders)) {
       if (!value) continue;
       const lower = key.toLowerCase();
-      if (lower === 'host' || lower === 'content-length') continue;
+      if (hopByHop.has(lower)) continue;
       headers[key] = value;
     }
 

tests/unit/cliproxy/codex-reasoning-proxy.test.js

@@ -30,6 +30,16 @@ describe('Codex Reasoning Proxy', () => {
 
       assert.strictEqual(map.get('same'), 'medium');
     });
+
+    it('returns empty map when all models undefined', () => {
+      const map = buildCodexModelEffortMap({});
+      assert.strictEqual(map.size, 0);
+    });
+
+    it('ignores empty string models', () => {
+      const map = buildCodexModelEffortMap({ defaultModel: '', opusModel: '  ' });
+      assert.strictEqual(map.size, 0);
+    });
   });
 
   describe('getEffortForModel', () => {
@@ -37,6 +47,11 @@ describe('Codex Reasoning Proxy', () => {
       const map = buildCodexModelEffortMap({ opusModel: 'm1' });
       assert.strictEqual(getEffortForModel('unknown', map, 'medium'), 'medium');
     });
+
+    it('handles null model', () => {
+      const map = buildCodexModelEffortMap({ opusModel: 'm1' });
+      assert.strictEqual(getEffortForModel(null, map, 'high'), 'high');
+    });
   });
 
   describe('injectReasoningEffortIntoBody', () => {
@@ -51,6 +66,11 @@ describe('Codex Reasoning Proxy', () => {
     it('leaves non-object bodies unchanged', () => {
       assert.strictEqual(injectReasoningEffortIntoBody('x', 'medium'), 'x');
     });
+
+    it('leaves array bodies unchanged (not treated as record)', () => {
+      const arr = [1, 2, 3];
+      assert.deepStrictEqual(injectReasoningEffortIntoBody(arr, 'high'), arr);
+    });
   });
 
   describe('model suffix aliasing', () => {