fix(codex): clear stale context-engine projection after overflow retry

SebTardif · SebTardif · commit 5438f8ad34bd · 2026-05-31T09:19:32.000-07:00
When a resumed Codex thread with a thread_bootstrap context-engine binding overflows during turn/start, the retry creates a fresh thread but preserved the old projection epoch in the saved binding. The fresh thread never received the projected context, creating a false binding invariant that makes future runs skip re-projection. After restartContextEngineCodexThread() creates the fresh retry thread, read the saved binding, detect the stale projection, clear it, and log the previous epoch for observability. Closes #88355 Signed-off-by: Sebastien Tardif <sebtardif@ncf.ca>
diff --git a/extensions/codex/src/app-server/run-attempt.context-engine.test.ts b/extensions/codex/src/app-server/run-attempt.context-engine.test.ts
@@ -1233,7 +1233,7 @@ describe("runCodexAppServerAttempt context-engine lifecycle", () => {
     const savedBinding = await readCodexAppServerBinding(sessionFile);
     expect(savedBinding?.threadId).toBe("thread-fresh");
     expect(savedBinding?.contextEngine?.engineId).toBe("lossless-claw");
-    expect(savedBinding?.contextEngine?.projection?.epoch).toBe("epoch-before");
+    expect(savedBinding?.contextEngine?.projection).toBeUndefined();
   });
 
   it("preserves a newer context-engine binding when a stale resumed thread overflows", async () => {
diff --git a/extensions/codex/src/app-server/run-attempt.ts b/extensions/codex/src/app-server/run-attempt.ts
@@ -1873,6 +1873,38 @@ export async function runCodexAppServerAttempt(
           );
         } else {
           thread = await restartContextEngineCodexThread();
+          // The fresh retry thread was not bootstrapped with the
+          // context-engine projection. Clear the stale projection from
+          // the saved binding so the next run will re-project instead
+          // of assuming the old epoch is still in the thread.
+          {
+            const retryBinding = await readCodexAppServerBinding(activeSessionFile);
+            if (
+              retryBinding &&
+              retryBinding.threadId === thread.threadId &&
+              retryBinding.contextEngine?.projection
+            ) {
+              const {
+                schemaVersion: _schemaVersion,
+                sessionFile: _boundSessionFile,
+                updatedAt: _updatedAt,
+                ...bindingForWrite
+              } = retryBinding;
+              await writeCodexAppServerBinding(activeSessionFile, {
+                ...bindingForWrite,
+                contextEngine: bindingForWrite.contextEngine
+                  ? { ...bindingForWrite.contextEngine, projection: undefined }
+                  : undefined,
+              });
+              embeddedAgentLog.info(
+                "codex app-server cleared stale context-engine projection after overflow retry",
+                {
+                  threadId: thread.threadId,
+                  previousEpoch: retryBinding.contextEngine.projection.epoch,
+                },
+              );
+            }
+          }
           emitCodexAppServerEvent(params, {
             stream: "codex_app_server.lifecycle",
             data: { phase: "thread_ready_retry", threadId: thread.threadId },
