fix(doctor): warn when stale Codex overrides shadow OAuth (#40143)

* fix(doctor): warn on stale codex provider overrides

* test(doctor): cover stored codex oauth warning path

* fix: narrow codex override doctor warning (#40143) (thanks @bde1)

* test: sync doctor e2e mocks after health-flow move (#40143) (thanks @bde1)

---------

Co-authored-by: bde1 <bde1@users.noreply.github.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

docs/gateway/doctor.md

@@ -66,6 +66,7 @@ cat ~/.openclaw/openclaw.json
 - Talk config migration from legacy flat `talk.*` fields into `talk.provider` + `talk.providers.<provider>`.
 - Browser migration checks for legacy Chrome extension configs and Chrome MCP readiness.
 - OpenCode provider override warnings (`models.providers.opencode` / `models.providers.opencode-go`).
+- Codex OAuth shadowing warnings (`models.providers.openai-codex`).
 - OAuth TLS prerequisites check for OpenAI Codex OAuth profiles.
 - Legacy on-disk state migration (sessions/agent dir/WhatsApp auth).
 - Legacy plugin manifest contract key migration (`speechProviders`, `realtimeTranscriptionProviders`, `realtimeVoiceProviders`, `mediaUnderstandingProviders`, `imageGenerationProviders`, `videoGenerationProviders`, `webFetchProviders`, `webSearchProviders` → `contracts`).
@@ -212,6 +213,16 @@ doctor prints platform-specific fix guidance. On macOS with a Homebrew Node, the
 fix is usually `brew postinstall ca-certificates`. With `--deep`, the probe runs
 even if the gateway is healthy.
 
+### 2c) Codex OAuth provider overrides
+
+If you previously added legacy OpenAI transport settings under
+`models.providers.openai-codex`, they can shadow the built-in Codex OAuth
+provider path that newer releases use automatically. Doctor warns when it sees
+those old transport settings alongside Codex OAuth so you can remove or rewrite
+the stale transport override and get the built-in routing/fallback behavior
+back. Custom proxies and header-only overrides are still supported and do not
+trigger this warning.
+
 ### 3) Legacy state migrations (disk layout)
 
 Doctor can migrate older on-disk layouts into the current structure: