[Feature Request] Performance degradation with high context window utilization (70%+) on extended reasoning tasks

Bug Description
I use Codex to perform an adversarial review loop with a scoring rubric against Spec files, Plan files, and code output that Opus generates. Opus 4.7 on xHigh effort still needs multiple review turns to reach my optimal score. My rubric crtieria include Correctness, Efficiency, Observability, Performance, Reliability, Safety, and Simplicity. I have anectdotally observed that the rubric scores have diminished when the context window is 70%+ full. I thought you all were addressing large context memory better. You have permission to review my session history. Nothing that I am working on is highly confidential or proprietary and I can rotate credentials fairly easily.

Environment Info

• Platform: darwin
• Terminal: vscode
• Version: 2.1.144
• Feedback ID: f52b49ec-ba60-4f68-99fb-9710780a812e

Errors

[{"error":"Error: Tool Glob not found\n    at yF7 (/$bunfs/root/src/entrypoints/cli.js:2762:13555)\n    at NA (/$bunfs/root/src/entrypoints/cli.js:562:21157)\n    at SA (/$bunfs/root/src/entrypoints/cli.js:562:39936)\n    at d5H (/$bunfs/root/src/entrypoints/cli.js:562:50746)\n    at QL_ (/$bunfs/root/src/entrypoints/cli.js:562:87777)\n    at JeH (/$bunfs/root/src/entrypoints/cli.js:562:86736)\n    at n5H (/$bunfs/root/src/entrypoints/cli.js:562:86555)\n    at X5 (/$bunfs/root/src/entrypoints/cli.js:562:82886)\n    at oH (/$bunfs/root/src/entrypoints/cli.js:562:6440)\n    at L48 (/$bunfs/root/src/entrypoints/cli.js:555:5409)","timestamp":"2026-05-20T17:25:53.622Z"},{"error":"Error: Tool Grep not found\n    at yF7 (/$bunfs/root/src/entrypoints/cli.js:2762:13555)\n    at NA (/$bunfs/root/src/entrypoints/cli.js:562:21157)\n    at SA (/$bunfs/root/src/entrypoints/cli.js:562:39936)\n    at d5H (/$bunfs/root/src/entrypoints/cli.js:562:50746)\n    at QL_ (/$bunfs/root/src/entrypoints/cli.js:562:87777)\n    at JeH (/$bunfs/root/src/entrypoints/cli.js:562:86736)\n    at n5H (/$bunfs/root/src/entrypoints/cli.js:562:86555)\n    at X5 (/$bunfs/root/src/entrypoints/cli.js:562:82886)\n    at oH (/$bunfs/root/src/entrypoints/cli.js:562:6440)\n    at L48 (/$bunfs/root/src/entrypoints/cli.js:555:5409)","timestamp":"2026-05-20T17:26:09.173Z"},{"error":"Error: Tool Grep not found\n    at yF7 (/$bunfs/root/src/entrypoints/cli.js:2762:13555)\n    at NA (/$bunfs/root/src/entrypoints/cli.js:562:21157)\n    at SA (/$bunfs/root/src/entrypoints/cli.js:562:39936)\n    at d5H (/$bunfs/root/src/entrypoints/cli.js:562:50746)\n    at QL_ (/$bunfs/root/src/entrypoints/cli.js:562:87777)\n    at JeH (/$bunfs/root/src/entrypoints/cli.js:562:86736)\n    at n5H (/$bunfs/root/src/entrypoints/cli.js:562:86555)\n    at X5 (/$bunfs/root/src/entrypoints/cli.js:562:82886)\n    at oH (/$bunfs/root/src/entrypoints/cli.js:562:6440)\n    at L48 (/$bunfs/root/src/entrypoints/cli.js:555:5409)","timestamp":"2026-05-20T17:26:09.407Z"},{"error":"Error: Tool Grep not found\n    at yF7 (/$bunfs/root/src/entrypoints/cli.js:2762:13555)\n    at NA (/$bunfs/root/src/entrypoints/cli.js:562:21157)\n    at SA (/$bunfs/root/src/entrypoints/cli.js:562:39936)\n    at d5H (/$bunfs/root/src/entrypoints/cli.js:562:50746)\n    at QL_ (/$bunfs/root/src/entrypoints/cli.js:562:87777)\n    at JeH (/$bunfs/root/src/entrypoints/cli.js:562:86736)\n    at n5H (/$bunfs/root/src/entrypoints/cli.js:562:86555)\n    at X5 (/$bunfs/root/src/entrypoints/cli.js:562:82886)\n    at oH (/$bunfs/root/src/entrypoints/cli.js:562:6440)\n    at L48 (/$bunfs/root/src/entrypoints/cli.js:555:5409)","timestamp":"2026-05-20T17:26:26.408Z"},{"error":"Error: Tool Grep not found\n    at yF7 (/$bunfs/root/src/entrypoints/cli.js:2762:13555)\n    at NA (/$bunfs/root/src/entrypoints/cli.js:562:21157)\n    at SA (/$bunfs/root/src/entrypoints/cli.js:562:39936)\n    at d5H (/$bunfs/root/src/entrypoints/cli.js:562:50746)\n    at QL_ (/$bunfs/root/src/entrypoints/cli.js:562:87777)\n    at JeH (/$bunfs/root/src/entrypoints/cli.js:562:86736)\n    at n5H (/$bunfs/root/src/entrypoints/cli.js:562:86555)\n    at X5 (/$bunfs/root/src/entrypoints/cli.js:562:82886)\n    at oH (/$bunfs/root/src/entrypoints/cli.js:562:6440)\n    at L48 (/$bunfs/root/src/entrypoints/cli.js:555:5409)","timestamp":"2026-05-20T17:26:26.934Z"},{"error":"Error: Tool Grep not found\n    at yF7 (/$bunfs/root/src/entrypoints/cli.js:2762:13555)\n    at NA (/$bunfs/root/src/entrypoints/cli.js:562:21157)\n    at SA (/$bunfs/root/src/entrypoints/cli.js:562:39936)\n    at d5H (/$bunfs/root/src/entrypoints/cli.js:562:50746)\n    at QL_ (/$bunfs/root/src/entrypoints/cli.js:562:87777)\n    at JeH (/$bunfs/root/src/entrypoints/cli.js:562:86736)\n    at n5H (/$bunfs/root/src/entrypoints/cli.js:562:8655…

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