fix(fal): write the onboarding default image model to mediaModels.image (#123447)

applyFalConfig wrote the default image model to
agents.defaults.imageGenerationModel, a retired key the runtime never
reads (image generation resolves agents.defaults.mediaModels.image,
and the retired key is reported as an unrecognized dead key by
config validation). After fal onboarding, image_generate still failed
with "No image-generation model configured." until a doctor --fix
migration ran. Write mediaModels.image directly, matching the vydra
and pixverse onboarding flows.

extensions/fal/onboard.test.ts

@@ -0,0 +1,37 @@
+// Fal tests cover onboard plugin behavior.
+import {
+  type OpenClawConfig,
+  resolveAgentModelPrimaryValue,
+} from "openclaw/plugin-sdk/provider-onboard";
+import { describe, expect, it } from "vitest";
+import { applyFalConfig, FAL_DEFAULT_IMAGE_MODEL_REF } from "./onboard.js";
+
+const emptyCfg: OpenClawConfig = {};
+
+describe("applyFalConfig", () => {
+  it("writes the default image model to mediaModels.image (the key the runtime reads)", () => {
+    const result = applyFalConfig(emptyCfg);
+
+    expect(resolveAgentModelPrimaryValue(result.agents?.defaults?.mediaModels?.image)).toBe(
+      FAL_DEFAULT_IMAGE_MODEL_REF,
+    );
+    // The retired key must stay untouched: nothing in the runtime reads it.
+    expect(result.agents?.defaults).not.toHaveProperty("imageGenerationModel");
+  });
+
+  it("does not overwrite an existing mediaModels.image default", () => {
+    const cfg = {
+      agents: {
+        defaults: {
+          mediaModels: { image: { primary: "other-provider/custom-model" } },
+        },
+      },
+    } as OpenClawConfig;
+
+    const result = applyFalConfig(cfg);
+
+    expect(resolveAgentModelPrimaryValue(result.agents?.defaults?.mediaModels?.image)).toBe(
+      "other-provider/custom-model",
+    );
+  });
+});

extensions/fal/onboard.ts

@@ -4,7 +4,7 @@ import type { OpenClawConfig } from "openclaw/plugin-sdk/provider-onboard";
 export const FAL_DEFAULT_IMAGE_MODEL_REF = "fal/fal-ai/flux/dev";
 
 export function applyFalConfig(cfg: OpenClawConfig): OpenClawConfig {
-  if (cfg.agents?.defaults?.imageGenerationModel) {
+  if (cfg.agents?.defaults?.mediaModels?.image) {
     return cfg;
   }
   return {
@@ -13,8 +13,9 @@ export function applyFalConfig(cfg: OpenClawConfig): OpenClawConfig {
       ...cfg.agents,
       defaults: {
         ...cfg.agents?.defaults,
-        imageGenerationModel: {
-          primary: FAL_DEFAULT_IMAGE_MODEL_REF,
+        mediaModels: {
+          ...cfg.agents?.defaults?.mediaModels,
+          image: { primary: FAL_DEFAULT_IMAGE_MODEL_REF },
         },
       },
     },