diff --git a/src/commands/models/set-image.ts b/src/commands/models/set-image.ts
index 0b15ff5e6..920418e4f 100644
--- a/src/commands/models/set-image.ts
+++ b/src/commands/models/set-image.ts
@@ -1,34 +1,10 @@
 import type { RuntimeEnv } from "../../runtime.js";
 import { logConfigUpdated } from "../../config/logging.js";
-import {
-  mergePrimaryFallbackConfig,
-  type PrimaryFallbackConfig,
-  resolveModelTarget,
-  updateConfig,
-} from "./shared.js";
+import { applyDefaultModelPrimaryUpdate, updateConfig } from "./shared.js";
 
 export async function modelsSetImageCommand(modelRaw: string, runtime: RuntimeEnv) {
   const updated = await updateConfig((cfg) => {
-    const resolved = resolveModelTarget({ raw: modelRaw, cfg });
-    const key = `${resolved.provider}/${resolved.model}`;
-    const nextModels = { ...cfg.agents?.defaults?.models };
-    if (!nextModels[key]) {
-      nextModels[key] = {};
-    }
-    return {
-      ...cfg,
-      agents: {
-        ...cfg.agents,
-        defaults: {
-          ...cfg.agents?.defaults,
-          imageModel: mergePrimaryFallbackConfig(
-            cfg.agents?.defaults?.imageModel as unknown as PrimaryFallbackConfig | undefined,
-            { primary: key },
-          ),
-          models: nextModels,
-        },
-      },
-    };
+    return applyDefaultModelPrimaryUpdate({ cfg, modelRaw, field: "imageModel" });
   });
 
   logConfigUpdated(runtime);
diff --git a/src/commands/models/set.ts b/src/commands/models/set.ts
index a6291f726..d0506acbd 100644
--- a/src/commands/models/set.ts
+++ b/src/commands/models/set.ts
@@ -1,34 +1,10 @@
 import type { RuntimeEnv } from "../../runtime.js";
 import { logConfigUpdated } from "../../config/logging.js";
-import {
-  mergePrimaryFallbackConfig,
-  type PrimaryFallbackConfig,
-  resolveModelTarget,
-  updateConfig,
-} from "./shared.js";
+import { applyDefaultModelPrimaryUpdate, updateConfig } from "./shared.js";
 
 export async function modelsSetCommand(modelRaw: string, runtime: RuntimeEnv) {
   const updated = await updateConfig((cfg) => {
-    const resolved = resolveModelTarget({ raw: modelRaw, cfg });
-    const key = `${resolved.provider}/${resolved.model}`;
-    const nextModels = { ...cfg.agents?.defaults?.models };
-    if (!nextModels[key]) {
-      nextModels[key] = {};
-    }
-    return {
-      ...cfg,
-      agents: {
-        ...cfg.agents,
-        defaults: {
-          ...cfg.agents?.defaults,
-          model: mergePrimaryFallbackConfig(
-            cfg.agents?.defaults?.model as unknown as PrimaryFallbackConfig | undefined,
-            { primary: key },
-          ),
-          models: nextModels,
-        },
-      },
-    };
+    return applyDefaultModelPrimaryUpdate({ cfg, modelRaw, field: "model" });
   });
 
   logConfigUpdated(runtime);
diff --git a/src/commands/models/shared.ts b/src/commands/models/shared.ts
index 9f65eebf8..64439ef60 100644
--- a/src/commands/models/shared.ts
+++ b/src/commands/models/shared.ts
@@ -169,6 +169,37 @@ export function mergePrimaryFallbackConfig(
   return next;
 }
 
+export function applyDefaultModelPrimaryUpdate(params: {
+  cfg: OpenClawConfig;
+  modelRaw: string;
+  field: "model" | "imageModel";
+}): OpenClawConfig {
+  const resolved = resolveModelTarget({ raw: params.modelRaw, cfg: params.cfg });
+  const key = `${resolved.provider}/${resolved.model}`;
+
+  const nextModels = { ...params.cfg.agents?.defaults?.models };
+  if (!nextModels[key]) {
+    nextModels[key] = {};
+  }
+
+  const defaults = params.cfg.agents?.defaults ?? {};
+  const existing = (defaults as Record<string, unknown>)[params.field] as
+    | PrimaryFallbackConfig
+    | undefined;
+
+  return {
+    ...params.cfg,
+    agents: {
+      ...params.cfg.agents,
+      defaults: {
+        ...defaults,
+        [params.field]: mergePrimaryFallbackConfig(existing, { primary: key }),
+        models: nextModels,
+      },
+    },
+  };
+}
+
 export { modelKey };
 export { DEFAULT_MODEL, DEFAULT_PROVIDER };