Codex Desktop ChatGPT Responses requests omit tools; standalone subscription compression cannot prove MCP recovery

Observed:

• Actual HTTP Responses payloads are valid JSON and reach Caveman.
• Payload sizes commonly 300–650 KB.
• caveman_retrieve is callable from the Codex agent.
• But the provider-bound Responses JSON has no top-level tools member at all.
• tool_choice:"auto" is present, but tools is absent.
• Consequently request-scoped inspection sees zero tools and cannot see caveman_retrieve.
• requests_eligible_for_compression remains zero across hundreds of requests.

v2.5 release notes say standalone proxies prove recovery from the request's own tool list. Current Codex Desktop appears to keep its local/MCP tool registry out of the provider request, so this proof mechanism cannot succeed.

Suggested direction: Allow Codex-native recovery proof based on a securely verified local MCP registration/session receipt rather than requiring the provider-bound tools array.

Platform

• Claude Code
• Codex
• Other: ___

Version / install method caveman-proxy bin-v1.1.6 / pnpm

Environment

• Windows 10
• Codex Desktop, version 26.908.70816 (released 14 Sept 2026)
• ChatGPT subscription auth
• caveman-proxy bin-v1.1.6
• /chatgpt/responses
• CAVEMAN_MODE=compress
• CAVEMAN_SUBSCRIPTION_COMPRESS=live_zone
• caveman_retrieve installed as Codex MCP and independently verified callable