[codex] fix empty stream success handling and unknown usage logs (#343)

* fix: preserve repeated short responses deltas

* fix empty stream success handling and unknown usage logs

* fix proxy usage metadata typing

* fix stream bookkeeping and explicit zero usage source

* fix sticky fast path and usage placeholder detection

src/shared/proxyLogMeta.d.ts

@@ -1,8 +1,11 @@
+export type ProxyLogUsageSource = 'upstream' | 'self-log' | 'unknown' | null;
+
 export type ParsedProxyLogMetadata = {
   clientKind: string | null;
   sessionId: string | null;
   downstreamPath: string | null;
   upstreamPath: string | null;
+  usageSource: ProxyLogUsageSource;
   messageText: string;
 };
 

src/shared/proxyLogMeta.js

@@ -3,8 +3,9 @@ export function parseProxyLogMetadata(rawMessage) {
   const sessionMatch = rawMessage.match(/\[session:([^\]]+)\]/i);
   const downstreamMatch = rawMessage.match(/\[downstream:([^\]]+)\]/i);
   const upstreamMatch = rawMessage.match(/\[upstream:([^\]]+)\]/i);
+  const usageMatch = rawMessage.match(/\[usage:([^\]]+)\]/i);
   const messageText = rawMessage.replace(
-    /^\s*(?:\[(?:client|session|downstream|upstream):[^\]]+\]\s*)+/i,
+    /^\s*(?:\[(?:client|session|downstream|upstream|usage):[^\]]+\]\s*)+/i,
     '',
   ).trim();
 
@@ -13,6 +14,7 @@ export function parseProxyLogMetadata(rawMessage) {
     sessionId: sessionMatch?.[1]?.trim() || null,
     downstreamPath: downstreamMatch?.[1]?.trim() || null,
     upstreamPath: upstreamMatch?.[1]?.trim() || null,
+    usageSource: usageMatch?.[1]?.trim() || null,
     messageText,
   };
 }

src/shared/proxyLogMeta.test.ts

@@ -5,12 +5,13 @@ import { parseProxyLogMetadata } from './proxyLogMeta.js';
 describe('proxyLogMeta', () => {
   it('parses all supported proxy log prefixes', () => {
     expect(parseProxyLogMetadata(
-      '[client:codex] [session:turn-1] [downstream:/v1/responses] [upstream:/responses] boom',
+      '[client:codex] [session:turn-1] [downstream:/v1/responses] [upstream:/responses] [usage:self-log] boom',
     )).toEqual({
       clientKind: 'codex',
       sessionId: 'turn-1',
       downstreamPath: '/v1/responses',
       upstreamPath: '/responses',
+      usageSource: 'self-log',
       messageText: 'boom',
     });
   });
@@ -21,6 +22,7 @@ describe('proxyLogMeta', () => {
       sessionId: null,
       downstreamPath: null,
       upstreamPath: null,
+      usageSource: null,
       messageText: 'network timeout',
     });
   });
@@ -31,6 +33,7 @@ describe('proxyLogMeta', () => {
       sessionId: 'turn-1',
       downstreamPath: null,
       upstreamPath: null,
+      usageSource: null,
       messageText: 'boom',
     });
 
@@ -39,6 +42,7 @@ describe('proxyLogMeta', () => {
       sessionId: null,
       downstreamPath: null,
       upstreamPath: null,
+      usageSource: null,
       messageText: 'boom',
     });
 
@@ -47,6 +51,7 @@ describe('proxyLogMeta', () => {
       sessionId: '1',
       downstreamPath: null,
       upstreamPath: '/x',
+      usageSource: null,
       messageText: 'msg',
     });
 
@@ -55,6 +60,7 @@ describe('proxyLogMeta', () => {
       sessionId: null,
       downstreamPath: null,
       upstreamPath: null,
+      usageSource: null,
       messageText: '',
     });
   });