Improve downstream client detection

src/server/routes/proxy/downstreamClientContext.test.ts

@@ -33,6 +33,16 @@ describe('isCodexResponsesSurface', () => {
     })).toBe(true);
   });
 
+  it('detects broader Codex official-client family headers from user-agent and originator prefixes', () => {
+    expect(isCodexResponsesSurface({
+      'user-agent': 'Mozilla/5.0 codex_chatgpt_desktop/1.2.3',
+    })).toBe(true);
+
+    expect(isCodexResponsesSurface({
+      originator: 'codex_vscode',
+    })).toBe(true);
+  });
+
   it('returns false for generic responses clients', () => {
     expect(isCodexResponsesSurface({
       'content-type': 'application/json',
@@ -50,6 +60,9 @@ describe('detectDownstreamClientContext', () => {
       },
     })).toEqual({
       clientKind: 'codex',
+      clientAppId: 'codex_cli_rs',
+      clientAppName: 'Codex CLI',
+      clientConfidence: 'exact',
       sessionId: 'codex-session-123',
       traceHint: 'codex-session-123',
     });
@@ -63,6 +76,37 @@ describe('detectDownstreamClientContext', () => {
       },
     })).toEqual({
       clientKind: 'codex',
+      clientAppId: 'codex',
+      clientAppName: 'Codex',
+      clientConfidence: 'heuristic',
+    });
+  });
+
+  it('recognizes broader Codex official-client user-agent families without requiring stainless headers', () => {
+    expect(detectDownstreamClientContext({
+      downstreamPath: '/v1/responses',
+      headers: {
+        'user-agent': 'Mozilla/5.0 codex_chatgpt_desktop/1.2.3',
+      },
+    })).toEqual({
+      clientKind: 'codex',
+      clientAppId: 'codex_chatgpt_desktop',
+      clientAppName: 'Codex Desktop',
+      clientConfidence: 'exact',
+    });
+  });
+
+  it('recognizes broader Codex official-client originator prefixes', () => {
+    expect(detectDownstreamClientContext({
+      downstreamPath: '/v1/responses',
+      headers: {
+        originator: 'codex_exec',
+      },
+    })).toEqual({
+      clientKind: 'codex',
+      clientAppId: 'codex_exec',
+      clientAppName: 'Codex Exec',
+      clientConfidence: 'exact',
     });
   });
 
@@ -79,6 +123,9 @@ describe('detectDownstreamClientContext', () => {
       body,
     })).toEqual({
       clientKind: 'claude_code',
+      clientAppId: 'claude_code',
+      clientAppName: 'Claude Code',
+      clientConfidence: 'exact',
       sessionId: 'f25958b8-e75c-455d-8b40-f006d87cc2a4',
       traceHint: 'f25958b8-e75c-455d-8b40-f006d87cc2a4',
     });
@@ -128,6 +175,9 @@ describe('detectDownstreamClientContext', () => {
       },
     })).toEqual({
       clientKind: 'gemini_cli',
+      clientAppId: 'gemini_cli',
+      clientAppName: 'Gemini CLI',
+      clientConfidence: 'exact',
     });
   });
 

src/server/routes/proxy/downstreamClientContext.ts

@@ -37,6 +37,64 @@ type DownstreamClientFingerprintRule = {
   match(input: DownstreamClientFingerprintInput): DownstreamClientConfidence | null;
 };
 
+type DownstreamProtocolClientApp = {
+  clientAppId: string;
+  clientAppName: string;
+  clientConfidence: DownstreamClientConfidence;
+};
+
+type HeaderPrefixMatcherRule = {
+  id: string;
+  name: string;
+  userAgentPrefixes?: string[];
+  originatorPrefixes?: string[];
+};
+
+const codexOfficialClientAppRules: HeaderPrefixMatcherRule[] = [
+  {
+    id: 'codex_cli_rs',
+    name: 'Codex CLI',
+    userAgentPrefixes: ['codex_cli_rs/'],
+    originatorPrefixes: ['codex_cli_rs'],
+  },
+  {
+    id: 'codex_vscode',
+    name: 'Codex VSCode',
+    userAgentPrefixes: ['codex_vscode/'],
+    originatorPrefixes: ['codex_vscode'],
+  },
+  {
+    id: 'codex_app',
+    name: 'Codex App',
+    userAgentPrefixes: ['codex_app/'],
+    originatorPrefixes: ['codex_app'],
+  },
+  {
+    id: 'codex_chatgpt_desktop',
+    name: 'Codex Desktop',
+    userAgentPrefixes: ['codex_chatgpt_desktop/', 'codex desktop/'],
+    originatorPrefixes: ['codex_chatgpt_desktop', 'codex desktop'],
+  },
+  {
+    id: 'codex_atlas',
+    name: 'Codex Atlas',
+    userAgentPrefixes: ['codex_atlas/'],
+    originatorPrefixes: ['codex_atlas'],
+  },
+  {
+    id: 'codex_exec',
+    name: 'Codex Exec',
+    userAgentPrefixes: ['codex_exec/'],
+    originatorPrefixes: ['codex_exec'],
+  },
+  {
+    id: 'codex_sdk_ts',
+    name: 'Codex SDK TS',
+    userAgentPrefixes: ['codex_sdk_ts/'],
+    originatorPrefixes: ['codex_sdk_ts'],
+  },
+];
+
 function isRecord(value: unknown): value is Record<string, unknown> {
   return !!value && typeof value === 'object' && !Array.isArray(value);
 }
@@ -80,6 +138,10 @@ function headerIncludes(headers: NormalizedClientHeaders, key: string, expectedF
   return (headers[key.trim().toLowerCase()] || []).some((value) => value.trim().toLowerCase().includes(normalizedExpected));
 }
 
+function headerMatchesPrefixes(headers: NormalizedClientHeaders, key: string, prefixes: string[]): boolean {
+  return prefixes.some((prefix) => headerIncludes(headers, key, prefix));
+}
+
 function buildBodySummary(body: unknown): DownstreamClientBodySummary {
   if (!isRecord(body)) {
     return {
@@ -158,6 +220,55 @@ function detectDownstreamClientFingerprint(input: {
   };
 }
 
+function detectCodexOfficialClientApp(headers: NormalizedClientHeaders): DownstreamProtocolClientApp | null {
+  for (const rule of codexOfficialClientAppRules) {
+    const matchesOriginator = Array.isArray(rule.originatorPrefixes)
+      && headerMatchesPrefixes(headers, 'originator', rule.originatorPrefixes);
+    const matchesUserAgent = Array.isArray(rule.userAgentPrefixes)
+      && headerMatchesPrefixes(headers, 'user-agent', rule.userAgentPrefixes);
+
+    if (!matchesOriginator && !matchesUserAgent) continue;
+
+    return {
+      clientAppId: rule.id,
+      clientAppName: rule.name,
+      clientConfidence: 'exact',
+    };
+  }
+
+  return null;
+}
+
+function detectProtocolClientApp(input: {
+  clientKind: DownstreamClientKind;
+  headers?: Record<string, unknown>;
+}): DownstreamProtocolClientApp | null {
+  switch (input.clientKind) {
+    case 'claude_code':
+      return {
+        clientAppId: 'claude_code',
+        clientAppName: 'Claude Code',
+        clientConfidence: 'exact',
+      };
+    case 'gemini_cli':
+      return {
+        clientAppId: 'gemini_cli',
+        clientAppName: 'Gemini CLI',
+        clientConfidence: 'exact',
+      };
+    case 'codex': {
+      const headers = normalizeHeaders(input.headers);
+      return detectCodexOfficialClientApp(headers) || {
+        clientAppId: 'codex',
+        clientAppName: 'Codex',
+        clientConfidence: 'heuristic',
+      };
+    }
+    default:
+      return null;
+  }
+}
+
 export function isCodexResponsesSurface(headers?: Record<string, unknown>): boolean {
   return isCodexResponsesSurfaceViaProfile(headers);
 }
@@ -173,10 +284,14 @@ export function detectDownstreamClientContext(input: {
 }): DownstreamClientContext {
   const detected = detectCliProfile(input);
   const fingerprint = detectDownstreamClientFingerprint(input);
+  const protocolClientApp = fingerprint ? null : detectProtocolClientApp({
+    clientKind: detected.id,
+    headers: input.headers,
+  });
   return {
     clientKind: detected.id,
     ...(detected.sessionId ? { sessionId: detected.sessionId } : {}),
     ...(detected.traceHint ? { traceHint: detected.traceHint } : {}),
-    ...(fingerprint || {}),
+    ...(fingerprint || protocolClientApp || {}),
   };
 }