docs(openai): canonicalize GPT model refs

docs/plugins/sdk-agent-harness.md

@@ -122,19 +122,19 @@ OpenClaw. The harness then claims that provider in `supports(...)`.
 The bundled Codex plugin follows this pattern:
 
 - provider id: `codex`
-- user model refs: `codex/gpt-5.5`, `codex/gpt-5.2`, or another model returned
-  by the Codex app server
+- user model refs: canonical `openai/gpt-5.5` plus
+  `embeddedHarness.runtime: "codex"`; legacy `codex/gpt-*` refs remain accepted
+  for compatibility
 - harness id: `codex`
 - auth: synthetic provider availability, because the Codex harness owns the
   native Codex login/session
 - app-server request: OpenClaw sends the bare model id to Codex and lets the
   harness talk to the native app-server protocol
 
-The Codex plugin is additive. Plain `openai/gpt-*` refs remain OpenAI provider
-refs and continue to use the normal OpenClaw provider path. Select `codex/gpt-*`
-when you want Codex-managed auth, Codex model discovery, native threads, and
-Codex app-server execution. `/model` can switch among the Codex models returned
-by the Codex app server without requiring OpenAI provider credentials.
+The Codex plugin is additive. Plain `openai/gpt-*` refs continue to use the
+normal OpenClaw provider path unless you force the Codex harness with
+`embeddedHarness.runtime: "codex"`. Older `codex/gpt-*` refs still select the
+Codex provider and harness for compatibility.
 
 For operator setup, model prefix examples, and Codex-only configs, see
 [Codex Harness](/plugins/codex-harness).
@@ -156,13 +156,9 @@ into the OpenClaw transcript.
 
 The bundled `codex` harness is the native Codex mode for embedded OpenClaw
 agent turns. Enable the bundled `codex` plugin first, and include `codex` in
-`plugins.allow` if your config uses a restrictive allowlist. It is different
-from `openai-codex/*`:
-
-- `openai-codex/*` uses ChatGPT/Codex OAuth through the normal OpenClaw provider
-  path.
-- `codex/*` uses the bundled Codex provider and routes the turn through Codex
-  app-server.
+`plugins.allow` if your config uses a restrictive allowlist. New configs should
+use `openai/gpt-*` with `embeddedHarness.runtime: "codex"`. Legacy
+`openai-codex/*` and `codex/*` model refs remain compatibility aliases.
 
 When this mode runs, Codex owns the native thread id, resume behavior,
 compaction, and app-server execution. OpenClaw still owns the chat channel,
@@ -189,7 +185,7 @@ For Codex-only embedded runs:
 {
   "agents": {
     "defaults": {
-      "model": "codex/gpt-5.5",
+      "model": "openai/gpt-5.5",
       "embeddedHarness": {
         "runtime": "codex",
         "fallback": "none"
@@ -230,7 +226,7 @@ Per-agent overrides use the same shape:
     "list": [
       {
         "id": "codex-only",
-        "model": "codex/gpt-5.5",
+        "model": "openai/gpt-5.5",
         "embeddedHarness": {
           "runtime": "codex",
           "fallback": "none"