diff --git a/docs/concepts/models.md b/docs/concepts/models.md
index 4b14320eeee..62d5bf07a70 100644
--- a/docs/concepts/models.md
+++ b/docs/concepts/models.md
@@ -119,7 +119,8 @@ openclaw config set agents.defaults.models '{"openai/gpt-5.4":{}}' --strict-json
 If `agents.defaults.models` is set, it becomes the **allowlist** for `/model` and for session overrides. When a user selects a model that isn't in that allowlist, OpenClaw returns:
 
 ```
-Model "provider/model" is not allowed. Use /model to list available models.
+Model "provider/model" is not allowed. Use /models to list providers, or /models <provider> to list models.
+Add it with: openclaw config set agents.defaults.models '{"provider/model":{}}' --strict-json --merge
 ```
 
 <Warning>
@@ -131,6 +132,8 @@ This happens **before** a normal reply is generated, so the message can feel lik
 
 </Warning>
 
+When the rejected command included a runtime override such as `/model openai/gpt-5.5 --runtime codex`, fix the allowlist first, then retry the same `/model ... --runtime ...` command. For native Codex execution, the selected model is still `openai/gpt-5.5`; the `codex` runtime selects the harness and uses Codex auth separately.
+
 For local/GGUF models, store the full provider-prefixed ref in the allowlist,
 for example `ollama/gemma4:26b`, `lmstudio/Gemma4-26b-a4-it-gguf`, or the
 exact provider/model shown by `openclaw models list --provider <provider>`.
diff --git a/docs/help/faq-models.md b/docs/help/faq-models.md
index c2de0dc49ff..e308029a98f 100644
--- a/docs/help/faq-models.md
+++ b/docs/help/faq-models.md
@@ -191,11 +191,14 @@ troubleshooting, see the main [FAQ](/help/faq).
     session overrides. Choosing a model that isn't in that list returns:
 
     ```
-    Model "provider/model" is not allowed. Use /model to list available models.
+    Model "provider/model" is not allowed. Use /models to list providers, or /models <provider> to list models.
+    Add it with: openclaw config set agents.defaults.models '{"provider/model":{}}' --strict-json --merge
     ```
 
     That error is returned **instead of** a normal reply. Fix: add the model to
     `agents.defaults.models`, remove the allowlist, or pick a model from `/model list`.
+    If the command also included `--runtime codex`, add the model first and then retry
+    the same `/model provider/model --runtime codex` command.
 
   </Accordion>
 
diff --git a/src/auto-reply/reply/directive-handling.model-selection.ts b/src/auto-reply/reply/directive-handling.model-selection.ts
index 33cfbe9d7f6..72cee70f949 100644
--- a/src/auto-reply/reply/directive-handling.model-selection.ts
+++ b/src/auto-reply/reply/directive-handling.model-selection.ts
@@ -80,6 +80,7 @@ export function resolveModelSelectionFromDirective(params: {
         defaultModel: params.defaultModel,
         aliasIndex: params.aliasIndex,
         allowedModelKeys: params.allowedModelKeys,
+        rawRuntime: params.directives.rawModelRuntime,
       })
     : null;
   const useStoredNumericProfile =
@@ -131,6 +132,7 @@ export function resolveModelSelectionFromDirective(params: {
       defaultModel: params.defaultModel,
       aliasIndex: params.aliasIndex,
       allowedModelKeys: params.allowedModelKeys,
+      rawRuntime: params.directives.rawModelRuntime,
     });
 
     if (resolved.error) {
diff --git a/src/auto-reply/reply/directive-handling.model.test.ts b/src/auto-reply/reply/directive-handling.model.test.ts
index ff41ea6e17f..758430c6eb0 100644
--- a/src/auto-reply/reply/directive-handling.model.test.ts
+++ b/src/auto-reply/reply/directive-handling.model.test.ts
@@ -611,6 +611,22 @@ describe("/model chat UX", () => {
     expect(resolved.errorText).toContain("Browse: /models or /models <provider>");
   });
 
+  it("includes additive allowlist repair when a runtime switch targets a blocked model", () => {
+    const resolved = resolveModelSelectionForCommand({
+      command: "/model openai/gpt-5.5 --runtime codex",
+      allowedModelKeys: new Set(["anthropic/claude-opus-4-6"]),
+      allowedModelCatalog: [],
+    });
+
+    expect(resolved.modelSelection).toBeUndefined();
+    expect(resolved.errorText).toContain('Model "openai/gpt-5.5" is not allowed.');
+    expect(resolved.errorText).toContain(
+      `openclaw config set agents.defaults.models '{"openai/gpt-5.5":{}}' --strict-json --merge`,
+    );
+    expect(resolved.errorText).toContain("Then retry: /model openai/gpt-5.5 --runtime codex");
+    expect(resolved.errorText).toContain("openclaw plugins enable codex");
+  });
+
   it("treats explicit default /model selection as resettable default", () => {
     const resolved = resolveModelSelectionForCommand({
       command: "/model anthropic/claude-opus-4-6",
diff --git a/src/auto-reply/reply/directive-handling.model.ts b/src/auto-reply/reply/directive-handling.model.ts
index 04f30858f09..3203c985bf1 100644
--- a/src/auto-reply/reply/directive-handling.model.ts
+++ b/src/auto-reply/reply/directive-handling.model.ts
@@ -265,6 +265,7 @@ export async function maybeHandleModelDirectiveInfo(params: {
           "",
           "Tap below to browse models, or use:",
           "/model <provider/model> to switch",
+          "/model <provider/model> --runtime <runtime> to switch harnesses",
           "/model status for details",
         ]
           .filter(Boolean)
diff --git a/src/auto-reply/reply/model-selection-directive.ts b/src/auto-reply/reply/model-selection-directive.ts
index bce6fa5d8d1..7200c1577b6 100644
--- a/src/auto-reply/reply/model-selection-directive.ts
+++ b/src/auto-reply/reply/model-selection-directive.ts
@@ -20,6 +20,29 @@ export type ModelDirectiveSelection = {
   alias?: string;
 };
 
+function formatAddModelCommand(modelRef: string): string {
+  return `openclaw config set agents.defaults.models '${JSON.stringify({ [modelRef]: {} })}' --strict-json --merge`;
+}
+
+function formatNotAllowedError(params: {
+  modelRef: string;
+  rawRuntime?: string | undefined;
+}): string {
+  const rawRuntime = params.rawRuntime?.trim();
+  const retryCommand = rawRuntime
+    ? `/model ${params.modelRef} --runtime ${rawRuntime}`
+    : `/model ${params.modelRef}`;
+  const lines = [
+    `Model "${params.modelRef}" is not allowed. Use /models to list providers, or /models <provider> to list models.`,
+    `Add it with: ${formatAddModelCommand(params.modelRef)}`,
+    `Then retry: ${retryCommand}`,
+  ];
+  if (rawRuntime && normalizeProviderId(rawRuntime) === "codex") {
+    lines.push("If the Codex runtime is missing, run: openclaw plugins enable codex");
+  }
+  return lines.join("\n");
+}
+
 const FUZZY_VARIANT_TOKENS = [
   "lightning",
   "preview",
@@ -238,6 +261,7 @@ export function resolveModelDirectiveSelection(params: {
   defaultModel: string;
   aliasIndex: ModelAliasIndex;
   allowedModelKeys: Set<string>;
+  rawRuntime?: string | undefined;
 }): { selection?: ModelDirectiveSelection; error?: string } {
   const { raw, defaultProvider, defaultModel, aliasIndex, allowedModelKeys } = params;
 
@@ -401,6 +425,9 @@ export function resolveModelDirectiveSelection(params: {
   }
 
   return {
-    error: `Model "${resolved.ref.provider}/${resolved.ref.model}" is not allowed. Use /models to list providers, or /models <provider> to list models.`,
+    error: formatNotAllowedError({
+      modelRef: `${resolved.ref.provider}/${resolved.ref.model}`,
+      rawRuntime: params.rawRuntime,
+    }),
   };
 }