Codex Desktop (Windows/MSIX) HKG edge returns 403 — reqwest UA not overridden → empty plugins marketplace, slash commands gone, Fast Mode missing

Cross-post of [Bug] reqwest HTTP clients missing User-Agent override → Cloudflare 403 from HKG edge on Codex Desktop 26.422.x · Issue #18456 · openai/codex · GitHub — posting here since Community is OpenAI-staff-monitored.

Version: Codex Desktop 26.422.2437.0 (MSIX, Microsoft Store, Windows 11) Location: Vietnam (tested on Viettel 5G + corporate ADSL, both route through Cloudflare HKG POP) Same account works fine on a different computer.

Root cause (confirmed via curl from the affected machine):

• curl -A "reqwest/0.12.0" https://chatgpt.com/backend-api/plugins/featured → 403 (Cloudflare)
• curl -A "Codex-Desktop/26.422.2437.0" ...same URL... → 401 (auth challenge — passes CF)
• curl -A "Mozilla/5.0 Chrome/131" ...same URL... → 200

-> Cloudflare WAF at HKG is blocking the default reqwest/* User-Agent. → Some Codex Rust HTTP clients are not overriding the UA (logs show codex_analytics, codex_core::plugins::manager, codex_core::plugins::startup_sync all hitting 403).

Impact: plugins marketplace empty, slash commands gone from UI, Fast Mode unavailable, settings menu broken. No local workaround — needs either (a) set UA on all reqwest clients in Codex, or (b) allowlist reqwest/* at CF edge.

Full reproduction + logs in GitHub issue #18456.