diff --git a/CHANGELOG.md b/CHANGELOG.md
index a73e2888af7..dfff788e944 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ Docs: https://docs.openclaw.ai
 
 - Security/Exec: detect obfuscated commands before exec allowlist decisions and require explicit approval for obfuscation patterns. (#8592) Thanks @CornBrother0x and @vincentkoc.
 - Agents/Compaction: pass `agentDir` into manual `/compact` command runs so compaction auth/profile resolution stays scoped to the active agent. (#24133) thanks @Glucksberg.
+- Agents/Models: codify `agents.defaults.model` / `agents.defaults.imageModel` config-boundary input as `string | {primary,fallbacks}`, split explicit vs effective model resolution, and fix `models status --agent` source attribution so defaults-inherited agents are labeled as `defaults` while runtime selection still honors defaults fallback. (#24210) thanks @bianbiandashen.
 - Security/Skills: escape user-controlled prompt, filename, and output-path values in `openai-image-gen` HTML gallery generation to prevent stored XSS in generated `index.html` output. (#12538) Thanks @CornBrother0x.
 - Security/Skills: harden `skill-creator` packaging by skipping symlink entries and rejecting files whose resolved paths escape the selected skill root. (#24260, #16959) Thanks @CornBrother0x and @vincentkoc.
 - Security/OTEL: redact sensitive values (API keys, tokens, credential fields) from diagnostics-otel log bodies, log attributes, and error/reason span fields before OTLP export. (#12542) Thanks @brandonwise.
diff --git a/docs/gateway/configuration-reference.md b/docs/gateway/configuration-reference.md
index 50f40998ca1..209427ca277 100644
--- a/docs/gateway/configuration-reference.md
+++ b/docs/gateway/configuration-reference.md
@@ -718,9 +718,15 @@ Time format in system prompt. Default: `auto` (OS preference).
 }
 ```
 
+- `model`: accepts either a string (`"provider/model"`) or an object (`{ primary, fallbacks }`).
+  - String form sets only the primary model.
+  - Object form sets primary plus ordered failover models.
+- `imageModel`: accepts either a string (`"provider/model"`) or an object (`{ primary, fallbacks }`).
+  - Used by the `image` tool path as its vision-model config.
+  - Also used as fallback routing when the selected/default model cannot accept image input.
 - `model.primary`: format `provider/model` (e.g. `anthropic/claude-opus-4-6`). If you omit the provider, OpenClaw assumes `anthropic` (deprecated).
 - `models`: the configured model catalog and allowlist for `/model`. Each entry can include `alias` (shortcut) and `params` (provider-specific: `temperature`, `maxTokens`).
-- `imageModel`: only used if the primary model lacks image input.
+- Config writers that mutate these fields (for example `/models set`, `/models set-image`, and fallback add/remove commands) save canonical object form and preserve existing fallback lists when possible.
 - `maxConcurrent`: max parallel agent runs across sessions (each session still serialized). Default: 1.
 
 **Built-in alias shorthands** (only apply when the model is in `agents.defaults.models`):
diff --git a/extensions/llm-task/src/llm-task-tool.ts b/extensions/llm-task/src/llm-task-tool.ts
index f40d0351fec..87588d7adbd 100644
--- a/extensions/llm-task/src/llm-task-tool.ts
+++ b/extensions/llm-task/src/llm-task-tool.ts
@@ -96,7 +96,11 @@ export function createLlmTaskTool(api: OpenClawPluginApi) {
 
       const pluginCfg = (api.pluginConfig ?? {}) as PluginCfg;
 
-      const primary = api.config?.agents?.defaults?.model?.primary;
+      const defaultsModel = api.config?.agents?.defaults?.model;
+      const primary =
+        typeof defaultsModel === "string"
+          ? defaultsModel.trim()
+          : (defaultsModel?.primary?.trim() ?? undefined);
       const primaryProvider = typeof primary === "string" ? primary.split("/")[0] : undefined;
       const primaryModel =
         typeof primary === "string" ? primary.split("/").slice(1).join("/") : undefined;
diff --git a/extensions/tlon/src/monitor/index.ts b/extensions/tlon/src/monitor/index.ts
index e9d9750537b..bbcfa3fedc7 100644
--- a/extensions/tlon/src/monitor/index.ts
+++ b/extensions/tlon/src/monitor/index.ts
@@ -422,11 +422,12 @@ export async function monitorTlonProvider(opts: MonitorTlonOpts = {}): Promise<v
               model?: string;
             };
             const extRoute = route as typeof route & { model?: string };
+            const defaultModel = cfg.agents?.defaults?.model;
             const modelInfo =
               extPayload.metadata?.model ||
               extPayload.model ||
               extRoute.model ||
-              cfg.agents?.defaults?.model?.primary;
+              (typeof defaultModel === "string" ? defaultModel : defaultModel?.primary);
             replyText = `${replyText}\n\n_[Generated by ${formatModelName(modelInfo)}]_`;
           }
 
diff --git a/src/agents/agent-scope.test.ts b/src/agents/agent-scope.test.ts
index d1d3c900a49..f921a131576 100644
--- a/src/agents/agent-scope.test.ts
+++ b/src/agents/agent-scope.test.ts
@@ -4,6 +4,8 @@ import type { OpenClawConfig } from "../config/config.js";
 import {
   resolveAgentConfig,
   resolveAgentDir,
+  resolveAgentEffectiveModelPrimary,
+  resolveAgentExplicitModelPrimary,
   resolveEffectiveModelFallbacks,
   resolveAgentModelFallbacksOverride,
   resolveAgentModelPrimary,
@@ -59,6 +61,43 @@ describe("resolveAgentConfig", () => {
     });
   });
 
+  it("resolves explicit and effective model primary separately", () => {
+    const cfgWithStringDefault = {
+      agents: {
+        defaults: {
+          model: "anthropic/claude-sonnet-4",
+        },
+        list: [{ id: "main" }],
+      },
+    } as unknown as OpenClawConfig;
+    expect(resolveAgentExplicitModelPrimary(cfgWithStringDefault, "main")).toBeUndefined();
+    expect(resolveAgentEffectiveModelPrimary(cfgWithStringDefault, "main")).toBe(
+      "anthropic/claude-sonnet-4",
+    );
+
+    const cfgWithObjectDefault: OpenClawConfig = {
+      agents: {
+        defaults: {
+          model: {
+            primary: "openai/gpt-5.2",
+            fallbacks: ["anthropic/claude-sonnet-4"],
+          },
+        },
+        list: [{ id: "main" }],
+      },
+    };
+    expect(resolveAgentExplicitModelPrimary(cfgWithObjectDefault, "main")).toBeUndefined();
+    expect(resolveAgentEffectiveModelPrimary(cfgWithObjectDefault, "main")).toBe("openai/gpt-5.2");
+
+    const cfgNoDefaults: OpenClawConfig = {
+      agents: {
+        list: [{ id: "main" }],
+      },
+    };
+    expect(resolveAgentExplicitModelPrimary(cfgNoDefaults, "main")).toBeUndefined();
+    expect(resolveAgentEffectiveModelPrimary(cfgNoDefaults, "main")).toBeUndefined();
+  });
+
   it("supports per-agent model primary+fallbacks", () => {
     const cfg: OpenClawConfig = {
       agents: {
@@ -81,6 +120,8 @@ describe("resolveAgentConfig", () => {
     };
 
     expect(resolveAgentModelPrimary(cfg, "linus")).toBe("anthropic/claude-opus-4");
+    expect(resolveAgentExplicitModelPrimary(cfg, "linus")).toBe("anthropic/claude-opus-4");
+    expect(resolveAgentEffectiveModelPrimary(cfg, "linus")).toBe("anthropic/claude-opus-4");
     expect(resolveAgentModelFallbacksOverride(cfg, "linus")).toEqual(["openai/gpt-5.2"]);
 
     // If fallbacks isn't present, we don't override the global fallbacks.
diff --git a/src/agents/agent-scope.ts b/src/agents/agent-scope.ts
index c1e5774e23a..c48cea9f690 100644
--- a/src/agents/agent-scope.ts
+++ b/src/agents/agent-scope.ts
@@ -1,5 +1,6 @@
 import path from "node:path";
 import type { OpenClawConfig } from "../config/config.js";
+import { resolveAgentModelFallbackValues } from "../config/model-input.js";
 import { resolveStateDir } from "../config/paths.js";
 import { createSubsystemLogger } from "../logging/subsystem.js";
 import {
@@ -142,16 +143,43 @@ export function resolveAgentSkillsFilter(
   return normalizeSkillFilter(resolveAgentConfig(cfg, agentId)?.skills);
 }
 
-export function resolveAgentModelPrimary(cfg: OpenClawConfig, agentId: string): string | undefined {
-  const raw = resolveAgentConfig(cfg, agentId)?.model;
-  if (!raw) {
+function resolveModelPrimary(raw: unknown): string | undefined {
+  if (typeof raw === "string") {
+    const trimmed = raw.trim();
+    return trimmed || undefined;
+  }
+  if (!raw || typeof raw !== "object") {
     return undefined;
   }
-  if (typeof raw === "string") {
-    return raw.trim() || undefined;
+  const primary = (raw as { primary?: unknown }).primary;
+  if (typeof primary !== "string") {
+    return undefined;
   }
-  const primary = raw.primary?.trim();
-  return primary || undefined;
+  const trimmed = primary.trim();
+  return trimmed || undefined;
+}
+
+export function resolveAgentExplicitModelPrimary(
+  cfg: OpenClawConfig,
+  agentId: string,
+): string | undefined {
+  const raw = resolveAgentConfig(cfg, agentId)?.model;
+  return resolveModelPrimary(raw);
+}
+
+export function resolveAgentEffectiveModelPrimary(
+  cfg: OpenClawConfig,
+  agentId: string,
+): string | undefined {
+  return (
+    resolveAgentExplicitModelPrimary(cfg, agentId) ??
+    resolveModelPrimary(cfg.agents?.defaults?.model)
+  );
+}
+
+// Backward-compatible alias. Prefer explicit/effective helpers at new call sites.
+export function resolveAgentModelPrimary(cfg: OpenClawConfig, agentId: string): string | undefined {
+  return resolveAgentExplicitModelPrimary(cfg, agentId);
 }
 
 export function resolveAgentModelFallbacksOverride(
@@ -178,10 +206,7 @@ export function resolveEffectiveModelFallbacks(params: {
   if (!params.hasSessionModelOverride) {
     return agentFallbacksOverride;
   }
-  const defaultFallbacks =
-    typeof params.cfg.agents?.defaults?.model === "object"
-      ? (params.cfg.agents.defaults.model.fallbacks ?? [])
-      : [];
+  const defaultFallbacks = resolveAgentModelFallbackValues(params.cfg.agents?.defaults?.model);
   return agentFallbacksOverride ?? defaultFallbacks;
 }
 
diff --git a/src/agents/model-fallback.ts b/src/agents/model-fallback.ts
index 7a7a192e8d4..b0050602590 100644
--- a/src/agents/model-fallback.ts
+++ b/src/agents/model-fallback.ts
@@ -1,4 +1,8 @@
 import type { OpenClawConfig } from "../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../config/model-input.js";
 import {
   ensureAuthProfileStore,
   getSoonestCooldownExpiry,
@@ -151,26 +155,13 @@ function resolveImageFallbackCandidates(params: {
   if (params.modelOverride?.trim()) {
     addRaw(params.modelOverride, false);
   } else {
-    const imageModel = params.cfg?.agents?.defaults?.imageModel as
-      | { primary?: string }
-      | string
-      | undefined;
-    const primary = typeof imageModel === "string" ? imageModel.trim() : imageModel?.primary;
+    const primary = resolveAgentModelPrimaryValue(params.cfg?.agents?.defaults?.imageModel);
     if (primary?.trim()) {
       addRaw(primary, false);
     }
   }
 
-  const imageFallbacks = (() => {
-    const imageModel = params.cfg?.agents?.defaults?.imageModel as
-      | { fallbacks?: string[] }
-      | string
-      | undefined;
-    if (imageModel && typeof imageModel === "object") {
-      return imageModel.fallbacks ?? [];
-    }
-    return [];
-  })();
+  const imageFallbacks = resolveAgentModelFallbackValues(params.cfg?.agents?.defaults?.imageModel);
 
   for (const raw of imageFallbacks) {
     addRaw(raw, true);
@@ -220,14 +211,7 @@ function resolveFallbackCandidates(params: {
     if (!sameModelCandidate(normalizedPrimary, configuredPrimary)) {
       return []; // Override model failed → go straight to configured default
     }
-    const model = params.cfg?.agents?.defaults?.model as
-      | { fallbacks?: string[] }
-      | string
-      | undefined;
-    if (model && typeof model === "object") {
-      return model.fallbacks ?? [];
-    }
-    return [];
+    return resolveAgentModelFallbackValues(params.cfg?.agents?.defaults?.model);
   })();
 
   for (const raw of modelFallbacks) {
diff --git a/src/agents/model-selection.ts b/src/agents/model-selection.ts
index 6f6773d5c61..6f6e6d10f09 100644
--- a/src/agents/model-selection.ts
+++ b/src/agents/model-selection.ts
@@ -1,6 +1,7 @@
 import type { OpenClawConfig } from "../config/config.js";
+import { resolveAgentModelPrimaryValue, toAgentModelListLike } from "../config/model-input.js";
 import { createSubsystemLogger } from "../logging/subsystem.js";
-import { resolveAgentConfig, resolveAgentModelPrimary } from "./agent-scope.js";
+import { resolveAgentConfig, resolveAgentEffectiveModelPrimary } from "./agent-scope.js";
 import { DEFAULT_MODEL, DEFAULT_PROVIDER } from "./defaults.js";
 import type { ModelCatalogEntry } from "./model-catalog.js";
 import { normalizeGoogleModelId } from "./models-config.providers.js";
@@ -259,13 +260,7 @@ export function resolveConfiguredModelRef(params: {
   defaultProvider: string;
   defaultModel: string;
 }): ModelRef {
-  const rawModel = (() => {
-    const raw = params.cfg.agents?.defaults?.model as { primary?: string } | string | undefined;
-    if (typeof raw === "string") {
-      return raw.trim();
-    }
-    return raw?.primary?.trim() ?? "";
-  })();
+  const rawModel = resolveAgentModelPrimaryValue(params.cfg.agents?.defaults?.model) ?? "";
   if (rawModel) {
     const trimmed = rawModel.trim();
     const aliasIndex = buildModelAliasIndex({
@@ -303,7 +298,7 @@ export function resolveDefaultModelForAgent(params: {
   agentId?: string;
 }): ModelRef {
   const agentModelOverride = params.agentId
-    ? resolveAgentModelPrimary(params.cfg, params.agentId)
+    ? resolveAgentEffectiveModelPrimary(params.cfg, params.agentId)
     : undefined;
   const cfg =
     agentModelOverride && agentModelOverride.length > 0
@@ -314,9 +309,7 @@ export function resolveDefaultModelForAgent(params: {
             defaults: {
               ...params.cfg.agents?.defaults,
               model: {
-                ...(typeof params.cfg.agents?.defaults?.model === "object"
-                  ? params.cfg.agents.defaults.model
-                  : undefined),
+                ...toAgentModelListLike(params.cfg.agents?.defaults?.model),
                 primary: agentModelOverride,
               },
             },
@@ -357,7 +350,7 @@ export function resolveSubagentSpawnModelSelection(params: {
       cfg: params.cfg,
       agentId: params.agentId,
     }) ??
-    normalizeModelSelection(params.cfg.agents?.defaults?.model?.primary) ??
+    normalizeModelSelection(resolveAgentModelPrimaryValue(params.cfg.agents?.defaults?.model)) ??
     `${runtimeDefault.provider}/${runtimeDefault.model}`
   );
 }
diff --git a/src/agents/pi-embedded-runner/run.ts b/src/agents/pi-embedded-runner/run.ts
index 9ae15591b1b..aa603b171ed 100644
--- a/src/agents/pi-embedded-runner/run.ts
+++ b/src/agents/pi-embedded-runner/run.ts
@@ -1,6 +1,7 @@
 import { randomBytes } from "node:crypto";
 import fs from "node:fs/promises";
 import type { ThinkLevel } from "../../auto-reply/thinking.js";
+import { resolveAgentModelFallbackValues } from "../../config/model-input.js";
 import { generateSecureToken } from "../../infra/secure-random.js";
 import { getGlobalHookRunner } from "../../plugins/hook-runner-global.js";
 import type { PluginHookBeforeAgentStartResult } from "../../plugins/types.js";
@@ -231,7 +232,7 @@ export async function runEmbeddedPiAgent(
       let modelId = (params.model ?? DEFAULT_MODEL).trim() || DEFAULT_MODEL;
       const agentDir = params.agentDir ?? resolveOpenClawAgentDir();
       const fallbackConfigured =
-        (params.config?.agents?.defaults?.model?.fallbacks?.length ?? 0) > 0;
+        resolveAgentModelFallbackValues(params.config?.agents?.defaults?.model).length > 0;
       await ensureOpenClawModelsJson(params.config, agentDir);
 
       // Run before_model_resolve hooks early so plugins can override the
diff --git a/src/agents/tools/image-tool.helpers.ts b/src/agents/tools/image-tool.helpers.ts
index ae98e40ba26..a1581cb2b94 100644
--- a/src/agents/tools/image-tool.helpers.ts
+++ b/src/agents/tools/image-tool.helpers.ts
@@ -1,5 +1,9 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import type { OpenClawConfig } from "../../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../../config/model-input.js";
 import { extractAssistantText } from "../pi-embedded-utils.js";
 
 export type ImageModelConfig = { primary?: string; fallbacks?: string[] };
@@ -51,12 +55,8 @@ export function coerceImageAssistantText(params: {
 }
 
 export function coerceImageModelConfig(cfg?: OpenClawConfig): ImageModelConfig {
-  const imageModel = cfg?.agents?.defaults?.imageModel as
-    | { primary?: string; fallbacks?: string[] }
-    | string
-    | undefined;
-  const primary = typeof imageModel === "string" ? imageModel.trim() : imageModel?.primary;
-  const fallbacks = typeof imageModel === "object" ? (imageModel?.fallbacks ?? []) : [];
+  const primary = resolveAgentModelPrimaryValue(cfg?.agents?.defaults?.imageModel);
+  const fallbacks = resolveAgentModelFallbackValues(cfg?.agents?.defaults?.imageModel);
   return {
     ...(primary?.trim() ? { primary: primary.trim() } : {}),
     ...(fallbacks.length > 0 ? { fallbacks } : {}),
diff --git a/src/auto-reply/reply/commands-status.ts b/src/auto-reply/reply/commands-status.ts
index 5cbc406ce92..50d007321c4 100644
--- a/src/auto-reply/reply/commands-status.ts
+++ b/src/auto-reply/reply/commands-status.ts
@@ -10,6 +10,7 @@ import {
   resolveMainSessionAlias,
 } from "../../agents/tools/sessions-helpers.js";
 import type { OpenClawConfig } from "../../config/config.js";
+import { toAgentModelListLike } from "../../config/model-input.js";
 import type { SessionEntry, SessionScope } from "../../config/sessions.js";
 import { logVerbose } from "../../globals.js";
 import {
@@ -164,7 +165,7 @@ export async function buildStatusReply(params: {
     agent: {
       ...agentDefaults,
       model: {
-        ...agentDefaults.model,
+        ...toAgentModelListLike(agentDefaults.model),
         primary: `${provider}/${model}`,
       },
       contextTokens,
diff --git a/src/commands/agent.ts b/src/commands/agent.ts
index 6eddcfe7d67..7ca8591faa4 100644
--- a/src/commands/agent.ts
+++ b/src/commands/agent.ts
@@ -2,7 +2,6 @@ import {
   listAgentIds,
   resolveAgentDir,
   resolveEffectiveModelFallbacks,
-  resolveAgentModelPrimary,
   resolveSessionAgentId,
   resolveAgentSkillsFilter,
   resolveAgentWorkspaceDir,
@@ -21,6 +20,7 @@ import {
   modelKey,
   normalizeModelRef,
   resolveConfiguredModelRef,
+  resolveDefaultModelForAgent,
   resolveThinkingDefault,
 } from "../agents/model-selection.js";
 import { runEmbeddedPiAgent } from "../agents/pi-embedded.js";
@@ -372,29 +372,9 @@ export async function agentCommand(
       sessionEntry = next;
     }
 
-    const agentModelPrimary = resolveAgentModelPrimary(cfg, sessionAgentId);
-    const cfgForModelSelection = agentModelPrimary
-      ? {
-          ...cfg,
-          agents: {
-            ...cfg.agents,
-            defaults: {
-              ...cfg.agents?.defaults,
-              model: {
-                ...(typeof cfg.agents?.defaults?.model === "object"
-                  ? cfg.agents.defaults.model
-                  : undefined),
-                primary: agentModelPrimary,
-              },
-            },
-          },
-        }
-      : cfg;
-
-    const configuredDefaultRef = resolveConfiguredModelRef({
-      cfg: cfgForModelSelection,
-      defaultProvider: DEFAULT_PROVIDER,
-      defaultModel: DEFAULT_MODEL,
+    const configuredDefaultRef = resolveDefaultModelForAgent({
+      cfg,
+      agentId: sessionAgentId,
     });
     const { provider: defaultProvider, model: defaultModel } = normalizeModelRef(
       configuredDefaultRef.provider,
diff --git a/src/commands/auth-choice.apply.github-copilot.ts b/src/commands/auth-choice.apply.github-copilot.ts
index cd67ae1cbdf..1ef474682af 100644
--- a/src/commands/auth-choice.apply.github-copilot.ts
+++ b/src/commands/auth-choice.apply.github-copilot.ts
@@ -1,3 +1,4 @@
+import { toAgentModelListLike } from "../config/model-input.js";
 import { githubCopilotLoginCommand } from "../providers/github-copilot-auth.js";
 import type { ApplyAuthChoiceParams, ApplyAuthChoiceResult } from "./auth-choice.apply.js";
 import { applyAuthProfileConfig } from "./onboard-auth.js";
@@ -49,9 +50,7 @@ export async function applyAuthChoiceGitHubCopilot(
         defaults: {
           ...nextConfig.agents?.defaults,
           model: {
-            ...(typeof nextConfig.agents?.defaults?.model === "object"
-              ? nextConfig.agents.defaults.model
-              : undefined),
+            ...toAgentModelListLike(nextConfig.agents?.defaults?.model),
             primary: model,
           },
         },
diff --git a/src/commands/auth-choice.apply.huggingface.test.ts b/src/commands/auth-choice.apply.huggingface.test.ts
index 0758d84b0fb..9cc77fceb43 100644
--- a/src/commands/auth-choice.apply.huggingface.test.ts
+++ b/src/commands/auth-choice.apply.huggingface.test.ts
@@ -1,4 +1,5 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { resolveAgentModelPrimaryValue } from "../config/model-input.js";
 import type { WizardPrompter } from "../wizard/prompts.js";
 import { applyAuthChoiceHuggingface } from "./auth-choice.apply.huggingface.js";
 import {
@@ -87,7 +88,9 @@ describe("applyAuthChoiceHuggingface", () => {
       provider: "huggingface",
       mode: "api_key",
     });
-    expect(result?.config.agents?.defaults?.model?.primary).toMatch(/^huggingface\/.+/);
+    expect(resolveAgentModelPrimaryValue(result?.config.agents?.defaults?.model)).toMatch(
+      /^huggingface\/.+/,
+    );
     expect(text).toHaveBeenCalledWith(
       expect.objectContaining({ message: expect.stringContaining("Hugging Face") }),
     );
@@ -173,7 +176,9 @@ describe("applyAuthChoiceHuggingface", () => {
     });
 
     expect(result).not.toBeNull();
-    expect(String(result?.config.agents?.defaults?.model?.primary)).toContain(":cheapest");
+    expect(String(resolveAgentModelPrimaryValue(result?.config.agents?.defaults?.model))).toContain(
+      ":cheapest",
+    );
     expect(note).toHaveBeenCalledWith(
       "Provider locked — router will choose backend by cost or speed.",
       "Hugging Face",
diff --git a/src/commands/auth-choice.apply.minimax.test.ts b/src/commands/auth-choice.apply.minimax.test.ts
index 43677529a7a..78ae5d5fa12 100644
--- a/src/commands/auth-choice.apply.minimax.test.ts
+++ b/src/commands/auth-choice.apply.minimax.test.ts
@@ -1,4 +1,5 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { resolveAgentModelPrimaryValue } from "../config/model-input.js";
 import type { WizardPrompter } from "../wizard/prompts.js";
 import { applyAuthChoiceMiniMax } from "./auth-choice.apply.minimax.js";
 import {
@@ -114,7 +115,9 @@ describe("applyAuthChoiceMiniMax", () => {
         provider,
         mode: "api_key",
       });
-      expect(result?.config.agents?.defaults?.model?.primary).toBe(expectedModel);
+      expect(resolveAgentModelPrimaryValue(result?.config.agents?.defaults?.model)).toBe(
+        expectedModel,
+      );
       expect(text).not.toHaveBeenCalled();
       expect(confirm).not.toHaveBeenCalled();
 
@@ -144,7 +147,9 @@ describe("applyAuthChoiceMiniMax", () => {
       provider: "minimax-cn",
       mode: "api_key",
     });
-    expect(result?.config.agents?.defaults?.model?.primary).toBe("minimax-cn/MiniMax-M2.5");
+    expect(resolveAgentModelPrimaryValue(result?.config.agents?.defaults?.model)).toBe(
+      "minimax-cn/MiniMax-M2.5",
+    );
     expect(text).not.toHaveBeenCalled();
     expect(confirm).toHaveBeenCalled();
 
@@ -176,7 +181,9 @@ describe("applyAuthChoiceMiniMax", () => {
       provider: "minimax",
       mode: "api_key",
     });
-    expect(result?.config.agents?.defaults?.model?.primary).toBe("minimax/MiniMax-M2.5-Lightning");
+    expect(resolveAgentModelPrimaryValue(result?.config.agents?.defaults?.model)).toBe(
+      "minimax/MiniMax-M2.5-Lightning",
+    );
     expect(text).not.toHaveBeenCalled();
     expect(confirm).not.toHaveBeenCalled();
 
diff --git a/src/commands/auth-choice.model-check.ts b/src/commands/auth-choice.model-check.ts
index b1579ea3483..ea7da2f9d6d 100644
--- a/src/commands/auth-choice.model-check.ts
+++ b/src/commands/auth-choice.model-check.ts
@@ -1,9 +1,7 @@
-import { resolveAgentModelPrimary } from "../agents/agent-scope.js";
 import { ensureAuthProfileStore, listProfilesForProvider } from "../agents/auth-profiles.js";
-import { DEFAULT_MODEL, DEFAULT_PROVIDER } from "../agents/defaults.js";
 import { getCustomProviderApiKey, resolveEnvApiKey } from "../agents/model-auth.js";
 import { loadModelCatalog } from "../agents/model-catalog.js";
-import { resolveConfiguredModelRef } from "../agents/model-selection.js";
+import { resolveDefaultModelForAgent } from "../agents/model-selection.js";
 import type { OpenClawConfig } from "../config/config.js";
 import type { WizardPrompter } from "../wizard/prompts.js";
 import { OPENAI_CODEX_DEFAULT_MODEL } from "./openai-codex-model-default.js";
@@ -13,35 +11,13 @@ export async function warnIfModelConfigLooksOff(
   prompter: WizardPrompter,
   options?: { agentId?: string; agentDir?: string },
 ) {
-  const agentModelOverride = options?.agentId
-    ? resolveAgentModelPrimary(config, options.agentId)
-    : undefined;
-  const configWithModel =
-    agentModelOverride && agentModelOverride.length > 0
-      ? {
-          ...config,
-          agents: {
-            ...config.agents,
-            defaults: {
-              ...config.agents?.defaults,
-              model: {
-                ...(typeof config.agents?.defaults?.model === "object"
-                  ? config.agents.defaults.model
-                  : undefined),
-                primary: agentModelOverride,
-              },
-            },
-          },
-        }
-      : config;
-  const ref = resolveConfiguredModelRef({
-    cfg: configWithModel,
-    defaultProvider: DEFAULT_PROVIDER,
-    defaultModel: DEFAULT_MODEL,
+  const ref = resolveDefaultModelForAgent({
+    cfg: config,
+    agentId: options?.agentId,
   });
   const warnings: string[] = [];
   const catalog = await loadModelCatalog({
-    config: configWithModel,
+    config,
     useCache: false,
   });
   if (catalog.length > 0) {
diff --git a/src/commands/auth-choice.moonshot.test.ts b/src/commands/auth-choice.moonshot.test.ts
index 647694c9ce4..780c0e8e71b 100644
--- a/src/commands/auth-choice.moonshot.test.ts
+++ b/src/commands/auth-choice.moonshot.test.ts
@@ -1,4 +1,5 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { resolveAgentModelPrimaryValue } from "../config/model-input.js";
 import type { WizardPrompter } from "../wizard/prompts.js";
 import { applyAuthChoice } from "./auth-choice.js";
 import {
@@ -72,7 +73,9 @@ describe("applyAuthChoice (moonshot)", () => {
     expect(text).toHaveBeenCalledWith(
       expect.objectContaining({ message: "Enter Moonshot API key (.cn)" }),
     );
-    expect(result.config.agents?.defaults?.model?.primary).toBe("anthropic/claude-opus-4-5");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "anthropic/claude-opus-4-5",
+    );
     expect(result.config.models?.providers?.moonshot?.baseUrl).toBe("https://api.moonshot.cn/v1");
     expect(result.agentModelOverride).toBe("moonshot/kimi-k2.5");
 
@@ -88,7 +91,9 @@ describe("applyAuthChoice (moonshot)", () => {
       setDefaultModel: true,
     });
 
-    expect(result.config.agents?.defaults?.model?.primary).toBe("moonshot/kimi-k2.5");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "moonshot/kimi-k2.5",
+    );
     expect(result.config.models?.providers?.moonshot?.baseUrl).toBe("https://api.moonshot.cn/v1");
     expect(result.agentModelOverride).toBeUndefined();
 
diff --git a/src/commands/auth-choice.test.ts b/src/commands/auth-choice.test.ts
index 308e6527065..0b8dfaeade2 100644
--- a/src/commands/auth-choice.test.ts
+++ b/src/commands/auth-choice.test.ts
@@ -1,6 +1,7 @@
 import fs from "node:fs/promises";
 import type { OAuthCredentials } from "@mariozechner/pi-ai";
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { resolveAgentModelPrimaryValue } from "../config/model-input.js";
 import type { WizardPrompter } from "../wizard/prompts.js";
 import { applyAuthChoice, resolvePreferredProviderForAuthChoice } from "./auth-choice.js";
 import { GOOGLE_GEMINI_DEFAULT_MODEL } from "./google-gemini-model-default.js";
@@ -278,7 +279,9 @@ describe("applyAuthChoice", () => {
       provider: "huggingface",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toMatch(/^huggingface\/.+/);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toMatch(
+      /^huggingface\/.+/,
+    );
 
     expect((await readAuthProfile("huggingface:default"))?.key).toBe("hf-test-token");
   });
@@ -310,7 +313,7 @@ describe("applyAuthChoice", () => {
       expect.objectContaining({ message: "Select Z.AI endpoint", initialValue: "global" }),
     );
     expect(result.config.models?.providers?.zai?.baseUrl).toBe(ZAI_CODING_CN_BASE_URL);
-    expect(result.config.agents?.defaults?.model?.primary).toBe("zai/glm-5");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe("zai/glm-5");
 
     expect((await readAuthProfile("zai:default"))?.key).toBe("zai-test-key");
   });
@@ -368,7 +371,9 @@ describe("applyAuthChoice", () => {
       expect.objectContaining({ message: "Select Z.AI endpoint" }),
     );
     expect(result.config.models?.providers?.zai?.baseUrl).toBe(ZAI_CODING_GLOBAL_BASE_URL);
-    expect(result.config.agents?.defaults?.model?.primary).toBe("zai/glm-4.5");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "zai/glm-4.5",
+    );
   });
 
   it("maps apiKey + tokenProvider=huggingface to huggingface-api-key flow", async () => {
@@ -396,7 +401,9 @@ describe("applyAuthChoice", () => {
       provider: "huggingface",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toMatch(/^huggingface\/.+/);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toMatch(
+      /^huggingface\/.+/,
+    );
     expect(text).not.toHaveBeenCalled();
 
     expect((await readAuthProfile("huggingface:default"))?.key).toBe("hf-token-provider-test");
@@ -425,7 +432,9 @@ describe("applyAuthChoice", () => {
       provider: "together",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toMatch(/^together\/.+/);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toMatch(
+      /^together\/.+/,
+    );
     expect(text).not.toHaveBeenCalled();
     expect(confirm).not.toHaveBeenCalled();
     expect((await readAuthProfile("together:default"))?.key).toBe(
@@ -456,7 +465,9 @@ describe("applyAuthChoice", () => {
       provider: "kimi-coding",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toMatch(/^kimi-coding\/.+/);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toMatch(
+      /^kimi-coding\/.+/,
+    );
     expect(text).not.toHaveBeenCalled();
     expect(confirm).not.toHaveBeenCalled();
     expect((await readAuthProfile("kimi-coding:default"))?.key).toBe("sk-kimi-token-provider-test");
@@ -485,7 +496,9 @@ describe("applyAuthChoice", () => {
       provider: "google",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe(GOOGLE_GEMINI_DEFAULT_MODEL);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      GOOGLE_GEMINI_DEFAULT_MODEL,
+    );
     expect(text).not.toHaveBeenCalled();
     expect(confirm).not.toHaveBeenCalled();
     expect((await readAuthProfile("google:default"))?.key).toBe("sk-gemini-token-provider-test");
@@ -514,7 +527,9 @@ describe("applyAuthChoice", () => {
       provider: "litellm",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toMatch(/^litellm\/.+/);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toMatch(
+      /^litellm\/.+/,
+    );
     expect(text).not.toHaveBeenCalled();
     expect(confirm).not.toHaveBeenCalled();
     expect((await readAuthProfile("litellm:default"))?.key).toBe("sk-litellm-token-provider-test");
@@ -612,7 +627,11 @@ describe("applyAuthChoice", () => {
         provider,
         mode: "api_key",
       });
-      expect(result.config.agents?.defaults?.model?.primary?.startsWith(modelPrefix)).toBe(true);
+      expect(
+        resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)?.startsWith(
+          modelPrefix,
+        ),
+      ).toBe(true);
       expect((await readAuthProfile(profileId))?.key).toBe(token);
     },
   );
@@ -642,7 +661,9 @@ describe("applyAuthChoice", () => {
       provider: "google",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe("openai/gpt-4o-mini");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "openai/gpt-4o-mini",
+    );
     expect(result.agentModelOverride).toBe(GOOGLE_GEMINI_DEFAULT_MODEL);
     expect((await readAuthProfile("google:default"))?.key).toBe("sk-gemini-test");
   });
@@ -706,7 +727,9 @@ describe("applyAuthChoice", () => {
       provider: "synthetic",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toMatch(/^synthetic\/.+/);
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toMatch(
+      /^synthetic\/.+/,
+    );
 
     expect((await readAuthProfile("synthetic:default"))?.key).toBe("sk-synthetic-env");
   });
@@ -731,7 +754,9 @@ describe("applyAuthChoice", () => {
       provider: "xai",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe("openai/gpt-4o-mini");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "openai/gpt-4o-mini",
+    );
     expect(result.agentModelOverride).toBe("xai/grok-4");
 
     expect((await readAuthProfile("xai:default"))?.key).toBe("sk-xai-test");
@@ -761,7 +786,9 @@ describe("applyAuthChoice", () => {
         setDefaultModel: true,
       });
 
-      expect(result.config.agents?.defaults?.model?.primary).toBe("github-copilot/gpt-4o");
+      expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+        "github-copilot/gpt-4o",
+      );
     } finally {
       if (previousIsTTYDescriptor) {
         Object.defineProperty(stdin, "isTTY", previousIsTTYDescriptor);
@@ -794,7 +821,9 @@ describe("applyAuthChoice", () => {
     expect(text).toHaveBeenCalledWith(
       expect.objectContaining({ message: "Enter OpenCode Zen API key" }),
     );
-    expect(result.config.agents?.defaults?.model?.primary).toBe("anthropic/claude-opus-4-5");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "anthropic/claude-opus-4-5",
+    );
     expect(result.config.models?.providers?.["opencode-zen"]).toBeUndefined();
     expect(result.agentModelOverride).toBe("opencode/claude-opus-4-6");
   });
@@ -868,7 +897,9 @@ describe("applyAuthChoice", () => {
       provider: "openrouter",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe("openrouter/auto");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "openrouter/auto",
+    );
 
     expect((await readAuthProfile("openrouter:default"))?.key).toBe("sk-openrouter-test");
 
@@ -963,7 +994,7 @@ describe("applyAuthChoice", () => {
       provider: "vercel-ai-gateway",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe(
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
       "vercel-ai-gateway/anthropic/claude-opus-4.6",
     );
 
@@ -1001,7 +1032,7 @@ describe("applyAuthChoice", () => {
       provider: "cloudflare-ai-gateway",
       mode: "api_key",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe(
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
       "cloudflare-ai-gateway/claude-sonnet-4-5",
     );
 
@@ -1178,7 +1209,9 @@ describe("applyAuthChoice", () => {
       provider: "qwen-portal",
       mode: "oauth",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe("qwen-portal/coder-model");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "qwen-portal/coder-model",
+    );
     expect(result.config.models?.providers?.["qwen-portal"]).toMatchObject({
       baseUrl: "https://portal.qwen.ai/v1",
       apiKey: "qwen-oauth",
@@ -1252,7 +1285,9 @@ describe("applyAuthChoice", () => {
       provider: "minimax-portal",
       mode: "oauth",
     });
-    expect(result.config.agents?.defaults?.model?.primary).toBe("minimax-portal/MiniMax-M2.1");
+    expect(resolveAgentModelPrimaryValue(result.config.agents?.defaults?.model)).toBe(
+      "minimax-portal/MiniMax-M2.1",
+    );
     expect(result.config.models?.providers?.["minimax-portal"]).toMatchObject({
       baseUrl: "https://api.minimax.io/anthropic",
       apiKey: "minimax-oauth",
diff --git a/src/commands/model-picker.ts b/src/commands/model-picker.ts
index 6b1c8691e02..db794210354 100644
--- a/src/commands/model-picker.ts
+++ b/src/commands/model-picker.ts
@@ -10,6 +10,7 @@ import {
   resolveConfiguredModelRef,
 } from "../agents/model-selection.js";
 import type { OpenClawConfig } from "../config/config.js";
+import { resolveAgentModelPrimaryValue } from "../config/model-input.js";
 import type { WizardPrompter, WizardSelectOption } from "../wizard/prompts.js";
 import { formatTokenK } from "./models/shared.js";
 import { OPENAI_CODEX_DEFAULT_MODEL } from "./openai-codex-model-default.js";
@@ -77,11 +78,7 @@ function createProviderAuthChecker(params: {
 }
 
 function resolveConfiguredModelRaw(cfg: OpenClawConfig): string {
-  const raw = cfg.agents?.defaults?.model as { primary?: string } | string | undefined;
-  if (typeof raw === "string") {
-    return raw.trim();
-  }
-  return raw?.primary?.trim() ?? "";
+  return resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model) ?? "";
 }
 
 function resolveConfiguredModelKeys(cfg: OpenClawConfig): string[] {
diff --git a/src/commands/models.set.test.ts b/src/commands/models.set.test.ts
index 70f8e2272fb..6671c6bb1f0 100644
--- a/src/commands/models.set.test.ts
+++ b/src/commands/models.set.test.ts
@@ -82,6 +82,25 @@ describe("models set + fallbacks", () => {
     });
   });
 
+  it("preserves primary when adding fallbacks to string defaults.model", async () => {
+    mockConfigSnapshot({ agents: { defaults: { model: "openai/gpt-4.1-mini" } } });
+    const runtime = makeRuntime();
+
+    await modelsFallbacksAddCommand("anthropic/claude-opus-4-6", runtime);
+
+    expect(writeConfigFile).toHaveBeenCalledTimes(1);
+    const written = getWrittenConfig();
+    expect(written.agents).toEqual({
+      defaults: {
+        model: {
+          primary: "openai/gpt-4.1-mini",
+          fallbacks: ["anthropic/claude-opus-4-6"],
+        },
+        models: { "anthropic/claude-opus-4-6": {} },
+      },
+    });
+  });
+
   it("normalizes provider casing in models set", async () => {
     mockConfigSnapshot({});
     const runtime = makeRuntime();
@@ -90,4 +109,20 @@ describe("models set + fallbacks", () => {
 
     expectWrittenPrimaryModel("zai/glm-4.7");
   });
+
+  it("rewrites string defaults.model to object form when setting primary", async () => {
+    mockConfigSnapshot({ agents: { defaults: { model: "openai/gpt-4.1-mini" } } });
+    const runtime = makeRuntime();
+
+    await modelsSetCommand("anthropic/claude-opus-4-6", runtime);
+
+    expect(writeConfigFile).toHaveBeenCalledTimes(1);
+    const written = getWrittenConfig();
+    expect(written.agents).toEqual({
+      defaults: {
+        model: { primary: "anthropic/claude-opus-4-6" },
+        models: { "anthropic/claude-opus-4-6": {} },
+      },
+    });
+  });
 });
diff --git a/src/commands/models/fallbacks-shared.ts b/src/commands/models/fallbacks-shared.ts
index dc540d9425b..736998fb4ec 100644
--- a/src/commands/models/fallbacks-shared.ts
+++ b/src/commands/models/fallbacks-shared.ts
@@ -2,12 +2,12 @@ import { buildModelAliasIndex, resolveModelRefFromString } from "../../agents/mo
 import type { OpenClawConfig } from "../../config/config.js";
 import { loadConfig } from "../../config/config.js";
 import { logConfigUpdated } from "../../config/logging.js";
+import { resolveAgentModelFallbackValues, toAgentModelListLike } from "../../config/model-input.js";
 import type { RuntimeEnv } from "../../runtime.js";
 import {
   DEFAULT_PROVIDER,
   ensureFlagCompatibility,
   mergePrimaryFallbackConfig,
-  type PrimaryFallbackConfig,
   modelKey,
   resolveModelTarget,
   resolveModelKeysFromEntries,
@@ -17,17 +17,14 @@ import {
 type DefaultsFallbackKey = "model" | "imageModel";
 
 function getFallbacks(cfg: OpenClawConfig, key: DefaultsFallbackKey): string[] {
-  const entry = cfg.agents?.defaults?.[key] as unknown as PrimaryFallbackConfig | undefined;
-  return entry?.fallbacks ?? [];
+  return resolveAgentModelFallbackValues(cfg.agents?.defaults?.[key]);
 }
 
 function patchDefaultsFallbacks(
   cfg: OpenClawConfig,
   params: { key: DefaultsFallbackKey; fallbacks: string[]; models?: Record<string, unknown> },
 ): OpenClawConfig {
-  const existing = cfg.agents?.defaults?.[params.key] as unknown as
-    | PrimaryFallbackConfig
-    | undefined;
+  const existing = toAgentModelListLike(cfg.agents?.defaults?.[params.key]);
   return {
     ...cfg,
     agents: {
diff --git a/src/commands/models/list.configured.ts b/src/commands/models/list.configured.ts
index a4300ea563a..fed70a4fe47 100644
--- a/src/commands/models/list.configured.ts
+++ b/src/commands/models/list.configured.ts
@@ -5,6 +5,10 @@ import {
   resolveModelRefFromString,
 } from "../../agents/model-selection.js";
 import type { OpenClawConfig } from "../../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../../config/model-input.js";
 import type { ConfiguredEntry } from "./list.types.js";
 import { DEFAULT_MODEL, DEFAULT_PROVIDER, modelKey } from "./shared.js";
 
@@ -37,16 +41,9 @@ export function resolveConfiguredEntries(cfg: OpenClawConfig) {
 
   addEntry(resolvedDefault, "default");
 
-  const modelConfig = cfg.agents?.defaults?.model as
-    | { primary?: string; fallbacks?: string[] }
-    | undefined;
-  const imageModelConfig = cfg.agents?.defaults?.imageModel as
-    | { primary?: string; fallbacks?: string[] }
-    | undefined;
-  const modelFallbacks = typeof modelConfig === "object" ? (modelConfig?.fallbacks ?? []) : [];
-  const imageFallbacks =
-    typeof imageModelConfig === "object" ? (imageModelConfig?.fallbacks ?? []) : [];
-  const imagePrimary = imageModelConfig?.primary?.trim() ?? "";
+  const modelFallbacks = resolveAgentModelFallbackValues(cfg.agents?.defaults?.model);
+  const imageFallbacks = resolveAgentModelFallbackValues(cfg.agents?.defaults?.imageModel);
+  const imagePrimary = resolveAgentModelPrimaryValue(cfg.agents?.defaults?.imageModel) ?? "";
 
   modelFallbacks.forEach((raw, idx) => {
     const resolved = resolveModelRefFromString({
diff --git a/src/commands/models/list.status-command.ts b/src/commands/models/list.status-command.ts
index 7e46c170cc0..830aefdf0af 100644
--- a/src/commands/models/list.status-command.ts
+++ b/src/commands/models/list.status-command.ts
@@ -2,8 +2,8 @@ import path from "node:path";
 import { resolveOpenClawAgentDir } from "../../agents/agent-paths.js";
 import {
   resolveAgentDir,
+  resolveAgentExplicitModelPrimary,
   resolveAgentModelFallbacksOverride,
-  resolveAgentModelPrimary,
 } from "../../agents/agent-scope.js";
 import {
   buildAuthHealthSummary,
@@ -26,6 +26,10 @@ import {
 import { formatCliCommand } from "../../cli/command-format.js";
 import { withProgressTotals } from "../../cli/progress.js";
 import { CONFIG_PATH, loadConfig } from "../../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../../config/model-input.js";
 import {
   formatUsageWindowSummary,
   loadProviderUsageSummary,
@@ -75,7 +79,7 @@ export async function modelsStatusCommand(
   const cfg = loadConfig();
   const agentId = resolveKnownAgentId({ cfg, rawAgentId: opts.agent });
   const agentDir = agentId ? resolveAgentDir(cfg, agentId) : resolveOpenClawAgentDir();
-  const agentModelPrimary = agentId ? resolveAgentModelPrimary(cfg, agentId) : undefined;
+  const agentModelPrimary = agentId ? resolveAgentExplicitModelPrimary(cfg, agentId) : undefined;
   const agentFallbacksOverride = agentId
     ? resolveAgentModelFallbacksOverride(cfg, agentId)
     : undefined;
@@ -87,24 +91,14 @@ export async function modelsStatusCommand(
         defaultModel: DEFAULT_MODEL,
       });
 
-  const modelConfig = cfg.agents?.defaults?.model as
-    | { primary?: string; fallbacks?: string[] }
-    | string
-    | undefined;
-  const imageConfig = cfg.agents?.defaults?.imageModel as
-    | { primary?: string; fallbacks?: string[] }
-    | string
-    | undefined;
-  const rawDefaultsModel =
-    typeof modelConfig === "string" ? modelConfig.trim() : (modelConfig?.primary?.trim() ?? "");
+  const rawDefaultsModel = resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model) ?? "";
   const rawModel = agentModelPrimary ?? rawDefaultsModel;
   const resolvedLabel = `${resolved.provider}/${resolved.model}`;
   const defaultLabel = rawModel || resolvedLabel;
-  const defaultsFallbacks = typeof modelConfig === "object" ? (modelConfig?.fallbacks ?? []) : [];
+  const defaultsFallbacks = resolveAgentModelFallbackValues(cfg.agents?.defaults?.model);
   const fallbacks = agentFallbacksOverride ?? defaultsFallbacks;
-  const imageModel =
-    typeof imageConfig === "string" ? imageConfig.trim() : (imageConfig?.primary?.trim() ?? "");
-  const imageFallbacks = typeof imageConfig === "object" ? (imageConfig?.fallbacks ?? []) : [];
+  const imageModel = resolveAgentModelPrimaryValue(cfg.agents?.defaults?.imageModel) ?? "";
+  const imageFallbacks = resolveAgentModelFallbackValues(cfg.agents?.defaults?.imageModel);
   const aliases = Object.entries(cfg.agents?.defaults?.models ?? {}).reduce<Record<string, string>>(
     (acc, [key, entry]) => {
       const alias = typeof entry?.alias === "string" ? entry.alias.trim() : undefined;
diff --git a/src/commands/models/list.status.test.ts b/src/commands/models/list.status.test.ts
index d8b3f8d4f12..b99cacc1cd4 100644
--- a/src/commands/models/list.status.test.ts
+++ b/src/commands/models/list.status.test.ts
@@ -32,7 +32,8 @@ const mocks = vi.hoisted(() => {
     store,
     resolveOpenClawAgentDir: vi.fn().mockReturnValue("/tmp/openclaw-agent"),
     resolveAgentDir: vi.fn().mockReturnValue("/tmp/openclaw-agent"),
-    resolveAgentModelPrimary: vi.fn().mockReturnValue(undefined),
+    resolveAgentExplicitModelPrimary: vi.fn().mockReturnValue(undefined),
+    resolveAgentEffectiveModelPrimary: vi.fn().mockReturnValue(undefined),
     resolveAgentModelFallbacksOverride: vi.fn().mockReturnValue(undefined),
     listAgentIds: vi.fn().mockReturnValue(["main", "jeremiah"]),
     ensureAuthProfileStore: vi.fn().mockReturnValue(store),
@@ -83,7 +84,8 @@ vi.mock("../../agents/agent-paths.js", () => ({
 
 vi.mock("../../agents/agent-scope.js", () => ({
   resolveAgentDir: mocks.resolveAgentDir,
-  resolveAgentModelPrimary: mocks.resolveAgentModelPrimary,
+  resolveAgentExplicitModelPrimary: mocks.resolveAgentExplicitModelPrimary,
+  resolveAgentEffectiveModelPrimary: mocks.resolveAgentEffectiveModelPrimary,
   resolveAgentModelFallbacksOverride: mocks.resolveAgentModelFallbacksOverride,
   listAgentIds: mocks.listAgentIds,
 }));
@@ -153,11 +155,13 @@ async function withAgentScopeOverrides<T>(
   },
   run: () => Promise<T>,
 ) {
-  const originalPrimary = mocks.resolveAgentModelPrimary.getMockImplementation();
+  const originalPrimary = mocks.resolveAgentExplicitModelPrimary.getMockImplementation();
+  const originalEffectivePrimary = mocks.resolveAgentEffectiveModelPrimary.getMockImplementation();
   const originalFallbacks = mocks.resolveAgentModelFallbacksOverride.getMockImplementation();
   const originalAgentDir = mocks.resolveAgentDir.getMockImplementation();
 
-  mocks.resolveAgentModelPrimary.mockReturnValue(overrides.primary);
+  mocks.resolveAgentExplicitModelPrimary.mockReturnValue(overrides.primary);
+  mocks.resolveAgentEffectiveModelPrimary.mockReturnValue(overrides.primary);
   mocks.resolveAgentModelFallbacksOverride.mockReturnValue(overrides.fallbacks);
   if (overrides.agentDir) {
     mocks.resolveAgentDir.mockReturnValue(overrides.agentDir);
@@ -167,9 +171,14 @@ async function withAgentScopeOverrides<T>(
     return await run();
   } finally {
     if (originalPrimary) {
-      mocks.resolveAgentModelPrimary.mockImplementation(originalPrimary);
+      mocks.resolveAgentExplicitModelPrimary.mockImplementation(originalPrimary);
     } else {
-      mocks.resolveAgentModelPrimary.mockReturnValue(undefined);
+      mocks.resolveAgentExplicitModelPrimary.mockReturnValue(undefined);
+    }
+    if (originalEffectivePrimary) {
+      mocks.resolveAgentEffectiveModelPrimary.mockImplementation(originalEffectivePrimary);
+    } else {
+      mocks.resolveAgentEffectiveModelPrimary.mockReturnValue(undefined);
     }
     if (originalFallbacks) {
       mocks.resolveAgentModelFallbacksOverride.mockImplementation(originalFallbacks);
@@ -262,6 +271,24 @@ describe("modelsStatusCommand auth overview", () => {
     );
   });
 
+  it("reports defaults source in JSON when --agent has no overrides", async () => {
+    const localRuntime = createRuntime();
+    await withAgentScopeOverrides(
+      {
+        primary: undefined,
+        fallbacks: undefined,
+      },
+      async () => {
+        await modelsStatusCommand({ json: true, agent: "main" }, localRuntime as never);
+        const payload = JSON.parse(String((localRuntime.log as Mock).mock.calls[0]?.[0]));
+        expect(payload.modelConfig).toEqual({
+          defaultSource: "defaults",
+          fallbacksSource: "defaults",
+        });
+      },
+    );
+  });
+
   it("throws when agent id is unknown", async () => {
     const localRuntime = createRuntime();
     await expect(modelsStatusCommand({ agent: "unknown" }, localRuntime as never)).rejects.toThrow(
diff --git a/src/commands/models/scan.ts b/src/commands/models/scan.ts
index 74b17b8ab86..c62ca0e107a 100644
--- a/src/commands/models/scan.ts
+++ b/src/commands/models/scan.ts
@@ -4,6 +4,7 @@ import { type ModelScanResult, scanOpenRouterModels } from "../../agents/model-s
 import { withProgressTotals } from "../../cli/progress.js";
 import { loadConfig } from "../../config/config.js";
 import { logConfigUpdated } from "../../config/logging.js";
+import { toAgentModelListLike } from "../../config/model-input.js";
 import type { RuntimeEnv } from "../../runtime.js";
 import {
   stylePromptHint,
@@ -297,9 +298,7 @@ export async function modelsScanCommand(
         nextModels[entry] = {};
       }
     }
-    const existingImageModel = cfg.agents?.defaults?.imageModel as
-      | { primary?: string; fallbacks?: string[] }
-      | undefined;
+    const existingImageModel = toAgentModelListLike(cfg.agents?.defaults?.imageModel);
     const nextImageModel =
       selectedImages.length > 0
         ? {
@@ -308,9 +307,7 @@ export async function modelsScanCommand(
             ...(opts.setImage ? { primary: selectedImages[0] } : {}),
           }
         : cfg.agents?.defaults?.imageModel;
-    const existingModel = cfg.agents?.defaults?.model as
-      | { primary?: string; fallbacks?: string[] }
-      | undefined;
+    const existingModel = toAgentModelListLike(cfg.agents?.defaults?.model);
     const defaults = {
       ...cfg.agents?.defaults,
       model: {
diff --git a/src/commands/models/set-image.ts b/src/commands/models/set-image.ts
index f4013141101..5fdf0c5f4e0 100644
--- a/src/commands/models/set-image.ts
+++ b/src/commands/models/set-image.ts
@@ -1,4 +1,5 @@
 import { logConfigUpdated } from "../../config/logging.js";
+import { resolveAgentModelPrimaryValue } from "../../config/model-input.js";
 import type { RuntimeEnv } from "../../runtime.js";
 import { applyDefaultModelPrimaryUpdate, updateConfig } from "./shared.js";
 
@@ -8,5 +9,7 @@ export async function modelsSetImageCommand(modelRaw: string, runtime: RuntimeEn
   });
 
   logConfigUpdated(runtime);
-  runtime.log(`Image model: ${updated.agents?.defaults?.imageModel?.primary ?? modelRaw}`);
+  runtime.log(
+    `Image model: ${resolveAgentModelPrimaryValue(updated.agents?.defaults?.imageModel) ?? modelRaw}`,
+  );
 }
diff --git a/src/commands/models/set.ts b/src/commands/models/set.ts
index 6b0e79e8c33..3316b05dd8e 100644
--- a/src/commands/models/set.ts
+++ b/src/commands/models/set.ts
@@ -1,4 +1,5 @@
 import { logConfigUpdated } from "../../config/logging.js";
+import { resolveAgentModelPrimaryValue } from "../../config/model-input.js";
 import type { RuntimeEnv } from "../../runtime.js";
 import { applyDefaultModelPrimaryUpdate, updateConfig } from "./shared.js";
 
@@ -8,5 +9,7 @@ export async function modelsSetCommand(modelRaw: string, runtime: RuntimeEnv) {
   });
 
   logConfigUpdated(runtime);
-  runtime.log(`Default model: ${updated.agents?.defaults?.model?.primary ?? modelRaw}`);
+  runtime.log(
+    `Default model: ${resolveAgentModelPrimaryValue(updated.agents?.defaults?.model) ?? modelRaw}`,
+  );
 }
diff --git a/src/commands/models/shared.ts b/src/commands/models/shared.ts
index 53836192e7d..925558aad11 100644
--- a/src/commands/models/shared.ts
+++ b/src/commands/models/shared.ts
@@ -12,6 +12,8 @@ import {
   readConfigFileSnapshot,
   writeConfigFile,
 } from "../../config/config.js";
+import { toAgentModelListLike } from "../../config/model-input.js";
+import type { AgentModelConfig } from "../../config/types.agents-shared.js";
 import { normalizeAgentId } from "../../routing/session-key.js";
 
 export const ensureFlagCompatibility = (opts: { json?: boolean; plain?: boolean }) => {
@@ -164,7 +166,8 @@ export function mergePrimaryFallbackConfig(
   existing: PrimaryFallbackConfig | undefined,
   patch: { primary?: string; fallbacks?: string[] },
 ): PrimaryFallbackConfig {
-  const next: PrimaryFallbackConfig = { ...existing };
+  const base = existing && typeof existing === "object" ? existing : undefined;
+  const next: PrimaryFallbackConfig = { ...base };
   if (patch.primary !== undefined) {
     next.primary = patch.primary;
   }
@@ -188,9 +191,9 @@ export function applyDefaultModelPrimaryUpdate(params: {
   }
 
   const defaults = params.cfg.agents?.defaults ?? {};
-  const existing = (defaults as Record<string, unknown>)[params.field] as
-    | PrimaryFallbackConfig
-    | undefined;
+  const existing = toAgentModelListLike(
+    (defaults as Record<string, unknown>)[params.field] as AgentModelConfig | undefined,
+  );
 
   return {
     ...params.cfg,
diff --git a/src/commands/onboard-auth.config-minimax.ts b/src/commands/onboard-auth.config-minimax.ts
index 1f3ca04a173..6314a641dbb 100644
--- a/src/commands/onboard-auth.config-minimax.ts
+++ b/src/commands/onboard-auth.config-minimax.ts
@@ -1,4 +1,5 @@
 import type { OpenClawConfig } from "../config/config.js";
+import { toAgentModelListLike } from "../config/model-input.js";
 import type { ModelProviderConfig } from "../config/types.models.js";
 import {
   applyAgentDefaultModelPrimary,
@@ -100,7 +101,7 @@ export function applyMinimaxHostedConfig(
       defaults: {
         ...next.agents?.defaults,
         model: {
-          ...next.agents?.defaults?.model,
+          ...toAgentModelListLike(next.agents?.defaults?.model),
           primary: MINIMAX_HOSTED_MODEL_REF,
         },
       },
diff --git a/src/commands/onboard-auth.test.ts b/src/commands/onboard-auth.test.ts
index 032a249b0d4..91a60c1eac6 100644
--- a/src/commands/onboard-auth.test.ts
+++ b/src/commands/onboard-auth.test.ts
@@ -4,6 +4,10 @@ import path from "node:path";
 import type { OAuthCredentials } from "@mariozechner/pi-ai";
 import { afterEach, describe, expect, it } from "vitest";
 import type { OpenClawConfig } from "../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../config/model-input.js";
 import {
   applyAuthProfileConfig,
   applyLitellmProviderConfig,
@@ -84,11 +88,15 @@ function createConfigWithFallbacks() {
 }
 
 function expectFallbacksPreserved(cfg: ReturnType<typeof applyMinimaxApiConfig>) {
-  expect(cfg.agents?.defaults?.model?.fallbacks).toEqual([...EXPECTED_FALLBACKS]);
+  expect(resolveAgentModelFallbackValues(cfg.agents?.defaults?.model)).toEqual([
+    ...EXPECTED_FALLBACKS,
+  ]);
 }
 
 function expectPrimaryModelPreserved(cfg: ReturnType<typeof applyMinimaxApiProviderConfig>) {
-  expect(cfg.agents?.defaults?.model?.primary).toBe("anthropic/claude-opus-4-5");
+  expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe(
+    "anthropic/claude-opus-4-5",
+  );
 }
 
 function expectAllowlistContains(
@@ -431,7 +439,7 @@ describe("applyZaiConfig", () => {
     for (const modelId of ["glm-4.7-flash", "glm-4.7-flashx"] as const) {
       const cfg = applyZaiConfig({}, { endpoint: "coding-cn", modelId });
       expect(cfg.models?.providers?.zai?.baseUrl).toBe(ZAI_CODING_CN_BASE_URL);
-      expect(cfg.agents?.defaults?.model?.primary).toBe(`zai/${modelId}`);
+      expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe(`zai/${modelId}`);
     }
   });
 });
@@ -479,7 +487,7 @@ describe("primary model defaults", () => {
     ] as const;
     for (const { getConfig, primaryModel } of configCases) {
       const cfg = getConfig();
-      expect(cfg.agents?.defaults?.model?.primary).toBe(primaryModel);
+      expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe(primaryModel);
     }
   });
 });
@@ -491,7 +499,7 @@ describe("applyXiaomiConfig", () => {
       baseUrl: "https://api.xiaomimimo.com/anthropic",
       api: "anthropic-messages",
     });
-    expect(cfg.agents?.defaults?.model?.primary).toBe("xiaomi/mimo-v2-flash");
+    expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe("xiaomi/mimo-v2-flash");
   });
 
   it("merges Xiaomi models and keeps existing provider overrides", () => {
@@ -521,7 +529,7 @@ describe("applyXaiConfig", () => {
       baseUrl: "https://api.x.ai/v1",
       api: "openai-completions",
     });
-    expect(cfg.agents?.defaults?.model?.primary).toBe(XAI_DEFAULT_MODEL_REF);
+    expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe(XAI_DEFAULT_MODEL_REF);
   });
 });
 
@@ -550,7 +558,9 @@ describe("applyMistralConfig", () => {
       baseUrl: "https://api.mistral.ai/v1",
       api: "openai-completions",
     });
-    expect(cfg.agents?.defaults?.model?.primary).toBe(MISTRAL_DEFAULT_MODEL_REF);
+    expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe(
+      MISTRAL_DEFAULT_MODEL_REF,
+    );
   });
 });
 
@@ -685,7 +695,7 @@ describe("default-model config helpers", () => {
     ] as const;
     for (const { applyConfig, primaryModel } of configCases) {
       const cfg = applyConfig({});
-      expect(cfg.agents?.defaults?.model?.primary).toBe(primaryModel);
+      expect(resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model)).toBe(primaryModel);
 
       const cfgWithFallbacks = applyConfig(createConfigWithFallbacks());
       expectFallbacksPreserved(cfgWithFallbacks);
diff --git a/src/commands/onboard-helpers.ts b/src/commands/onboard-helpers.ts
index 48f9e87c31e..6e029531f50 100644
--- a/src/commands/onboard-helpers.ts
+++ b/src/commands/onboard-helpers.ts
@@ -6,6 +6,7 @@ import { cancel, isCancel } from "@clack/prompts";
 import { DEFAULT_AGENT_WORKSPACE_DIR, ensureAgentWorkspace } from "../agents/workspace.js";
 import type { OpenClawConfig } from "../config/config.js";
 import { CONFIG_PATH } from "../config/config.js";
+import { resolveAgentModelPrimaryValue } from "../config/model-input.js";
 import { resolveSessionTranscriptsDirForAgent } from "../config/sessions.js";
 import { callGateway } from "../gateway/call.js";
 import { normalizeControlUiBasePath } from "../gateway/control-ui-shared.js";
@@ -43,7 +44,7 @@ export function summarizeExistingConfig(config: OpenClawConfig): string {
     rows.push(shortenHomeInString(`workspace: ${defaults.workspace}`));
   }
   if (defaults?.model) {
-    const model = typeof defaults.model === "string" ? defaults.model : defaults.model.primary;
+    const model = resolveAgentModelPrimaryValue(defaults.model);
     if (model) {
       rows.push(shortenHomeInString(`model: ${model}`));
     }
diff --git a/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts b/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts
index 1fec5ba6d60..87df6130336 100644
--- a/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts
+++ b/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts
@@ -1,6 +1,7 @@
 import fs from "node:fs/promises";
 import path from "node:path";
 import { describe, expect, it, vi } from "vitest";
+import { resolveAgentModelFallbackValues, resolveAgentModelPrimaryValue } from "./model-input.js";
 
 const { loadConfig, migrateLegacyConfig, readConfigFileSnapshot, validateConfigObject } =
   await vi.importActual<typeof import("./config.js")>("./config.js");
@@ -241,10 +242,16 @@ describe("legacy config detection", () => {
       },
     });
 
-    expect(res.config?.agents?.defaults?.model?.primary).toBe("anthropic/claude-opus-4-5");
-    expect(res.config?.agents?.defaults?.model?.fallbacks).toEqual(["openai/gpt-4.1-mini"]);
-    expect(res.config?.agents?.defaults?.imageModel?.primary).toBe("openai/gpt-4.1-mini");
-    expect(res.config?.agents?.defaults?.imageModel?.fallbacks).toEqual([
+    expect(resolveAgentModelPrimaryValue(res.config?.agents?.defaults?.model)).toBe(
+      "anthropic/claude-opus-4-5",
+    );
+    expect(resolveAgentModelFallbackValues(res.config?.agents?.defaults?.model)).toEqual([
+      "openai/gpt-4.1-mini",
+    ]);
+    expect(resolveAgentModelPrimaryValue(res.config?.agents?.defaults?.imageModel)).toBe(
+      "openai/gpt-4.1-mini",
+    );
+    expect(resolveAgentModelFallbackValues(res.config?.agents?.defaults?.imageModel)).toEqual([
       "anthropic/claude-opus-4-5",
     ]);
     expect(res.config?.agents?.defaults?.models?.["anthropic/claude-opus-4-5"]).toMatchObject({
diff --git a/src/config/config.schema-regressions.test.ts b/src/config/config.schema-regressions.test.ts
index 95eb4219455..ff42403f868 100644
--- a/src/config/config.schema-regressions.test.ts
+++ b/src/config/config.schema-regressions.test.ts
@@ -91,6 +91,19 @@ describe("config schema regressions", () => {
     expect(res.ok).toBe(true);
   });
 
+  it("accepts string values for agents defaults model inputs", () => {
+    const res = validateConfigObject({
+      agents: {
+        defaults: {
+          model: "anthropic/claude-opus-4-6",
+          imageModel: "openai/gpt-4.1-mini",
+        },
+      },
+    });
+
+    expect(res.ok).toBe(true);
+  });
+
   it("rejects relative iMessage attachment roots", () => {
     const res = validateConfigObject({
       channels: {
diff --git a/src/config/defaults.ts b/src/config/defaults.ts
index 3af51ba38d8..55d7093dde0 100644
--- a/src/config/defaults.ts
+++ b/src/config/defaults.ts
@@ -1,6 +1,7 @@
 import { DEFAULT_CONTEXT_TOKENS } from "../agents/defaults.js";
 import { normalizeProviderId, parseModelRef } from "../agents/model-selection.js";
 import { DEFAULT_AGENT_MAX_CONCURRENT, DEFAULT_SUBAGENT_MAX_CONCURRENT } from "./agent-limits.js";
+import { resolveAgentModelPrimaryValue } from "./model-input.js";
 import { resolveTalkApiKey } from "./talk.js";
 import type { OpenClawConfig } from "./types.js";
 import type { ModelDefinitionConfig } from "./types.models.js";
@@ -427,7 +428,9 @@ export function applyContextPruningDefaults(cfg: OpenClawConfig): OpenClawConfig
       modelsMutated = true;
     }
 
-    const primary = resolvePrimaryModelRef(defaults.model?.primary ?? undefined);
+    const primary = resolvePrimaryModelRef(
+      resolveAgentModelPrimaryValue(defaults.model) ?? undefined,
+    );
     if (primary) {
       const parsedPrimary = parseModelRef(primary, "anthropic");
       if (parsedPrimary?.provider === "anthropic") {
diff --git a/src/config/model-input.ts b/src/config/model-input.ts
new file mode 100644
index 00000000000..197947ab853
--- /dev/null
+++ b/src/config/model-input.ts
@@ -0,0 +1,36 @@
+import type { AgentModelConfig } from "./types.agents-shared.js";
+
+type AgentModelListLike = {
+  primary?: string;
+  fallbacks?: string[];
+};
+
+export function resolveAgentModelPrimaryValue(model?: AgentModelConfig): string | undefined {
+  if (typeof model === "string") {
+    const trimmed = model.trim();
+    return trimmed || undefined;
+  }
+  if (!model || typeof model !== "object") {
+    return undefined;
+  }
+  const primary = model.primary?.trim();
+  return primary || undefined;
+}
+
+export function resolveAgentModelFallbackValues(model?: AgentModelConfig): string[] {
+  if (!model || typeof model !== "object") {
+    return [];
+  }
+  return Array.isArray(model.fallbacks) ? model.fallbacks : [];
+}
+
+export function toAgentModelListLike(model?: AgentModelConfig): AgentModelListLike | undefined {
+  if (typeof model === "string") {
+    const primary = model.trim();
+    return primary ? { primary } : undefined;
+  }
+  if (!model || typeof model !== "object") {
+    return undefined;
+  }
+  return model;
+}
diff --git a/src/config/types.agent-defaults.ts b/src/config/types.agent-defaults.ts
index 3af07f83a18..7ecfc6d4193 100644
--- a/src/config/types.agent-defaults.ts
+++ b/src/config/types.agent-defaults.ts
@@ -118,10 +118,10 @@ export type CliBackendConfig = {
 };
 
 export type AgentDefaultsConfig = {
-  /** Primary model and fallbacks (provider/model). */
-  model?: AgentModelListConfig;
-  /** Optional image-capable model and fallbacks (provider/model). */
-  imageModel?: AgentModelListConfig;
+  /** Primary model and fallbacks (provider/model). Accepts string or {primary,fallbacks}. */
+  model?: AgentModelConfig;
+  /** Optional image-capable model and fallbacks (provider/model). Accepts string or {primary,fallbacks}. */
+  imageModel?: AgentModelConfig;
   /** Model catalog with optional aliases (full provider/model keys). */
   models?: Record<string, AgentModelEntryConfig>;
   /** Agent working directory (preferred). Used as the default cwd for agent runs. */
diff --git a/src/config/zod-schema.agent-defaults.ts b/src/config/zod-schema.agent-defaults.ts
index 76386659018..a4fb3c2443b 100644
--- a/src/config/zod-schema.agent-defaults.ts
+++ b/src/config/zod-schema.agent-defaults.ts
@@ -15,20 +15,8 @@ import {
 
 export const AgentDefaultsSchema = z
   .object({
-    model: z
-      .object({
-        primary: z.string().optional(),
-        fallbacks: z.array(z.string()).optional(),
-      })
-      .strict()
-      .optional(),
-    imageModel: z
-      .object({
-        primary: z.string().optional(),
-        fallbacks: z.array(z.string()).optional(),
-      })
-      .strict()
-      .optional(),
+    model: AgentModelSchema.optional(),
+    imageModel: AgentModelSchema.optional(),
     models: z
       .record(
         z.string(),
diff --git a/src/media-understanding/runner.ts b/src/media-understanding/runner.ts
index ad7b28328d9..c2ffe584448 100644
--- a/src/media-understanding/runner.ts
+++ b/src/media-understanding/runner.ts
@@ -10,6 +10,10 @@ import {
 } from "../agents/model-catalog.js";
 import type { MsgContext } from "../auto-reply/templating.js";
 import type { OpenClawConfig } from "../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../config/model-input.js";
 import type {
   MediaUnderstandingConfig,
   MediaUnderstandingModelConfig,
@@ -418,28 +422,19 @@ async function resolveKeyEntry(params: {
 }
 
 function resolveImageModelFromAgentDefaults(cfg: OpenClawConfig): MediaUnderstandingModelConfig[] {
-  const imageModel = cfg.agents?.defaults?.imageModel as
-    | { primary?: string; fallbacks?: string[] }
-    | string
-    | undefined;
-  if (!imageModel) {
-    return [];
-  }
   const refs: string[] = [];
-  if (typeof imageModel === "string") {
-    if (imageModel.trim()) {
-      refs.push(imageModel.trim());
-    }
-  } else {
-    if (imageModel.primary?.trim()) {
-      refs.push(imageModel.primary.trim());
-    }
-    for (const fb of imageModel.fallbacks ?? []) {
-      if (fb?.trim()) {
-        refs.push(fb.trim());
-      }
+  const primary = resolveAgentModelPrimaryValue(cfg.agents?.defaults?.imageModel);
+  if (primary?.trim()) {
+    refs.push(primary.trim());
+  }
+  for (const fb of resolveAgentModelFallbackValues(cfg.agents?.defaults?.imageModel)) {
+    if (fb?.trim()) {
+      refs.push(fb.trim());
     }
   }
+  if (refs.length === 0) {
+    return [];
+  }
   const entries: MediaUnderstandingModelConfig[] = [];
   for (const ref of refs) {
     const slashIdx = ref.indexOf("/");
diff --git a/src/security/audit-extra.sync.ts b/src/security/audit-extra.sync.ts
index fa13e9b53f7..6d36341f80d 100644
--- a/src/security/audit-extra.sync.ts
+++ b/src/security/audit-extra.sync.ts
@@ -14,6 +14,10 @@ import { resolveToolProfilePolicy } from "../agents/tool-policy.js";
 import { resolveBrowserConfig } from "../browser/config.js";
 import { formatCliCommand } from "../cli/command-format.js";
 import type { OpenClawConfig } from "../config/config.js";
+import {
+  resolveAgentModelFallbackValues,
+  resolveAgentModelPrimaryValue,
+} from "../config/model-input.js";
 import type { AgentToolsConfig } from "../config/types.tools.js";
 import { resolveGatewayAuth } from "../gateway/auth.js";
 import {
@@ -106,12 +110,20 @@ function addModel(models: ModelRef[], raw: unknown, source: string) {
 
 function collectModels(cfg: OpenClawConfig): ModelRef[] {
   const out: ModelRef[] = [];
-  addModel(out, cfg.agents?.defaults?.model?.primary, "agents.defaults.model.primary");
-  for (const f of cfg.agents?.defaults?.model?.fallbacks ?? []) {
+  addModel(
+    out,
+    resolveAgentModelPrimaryValue(cfg.agents?.defaults?.model),
+    "agents.defaults.model.primary",
+  );
+  for (const f of resolveAgentModelFallbackValues(cfg.agents?.defaults?.model)) {
     addModel(out, f, "agents.defaults.model.fallbacks");
   }
-  addModel(out, cfg.agents?.defaults?.imageModel?.primary, "agents.defaults.imageModel.primary");
-  for (const f of cfg.agents?.defaults?.imageModel?.fallbacks ?? []) {
+  addModel(
+    out,
+    resolveAgentModelPrimaryValue(cfg.agents?.defaults?.imageModel),
+    "agents.defaults.imageModel.primary",
+  );
+  for (const f of resolveAgentModelFallbackValues(cfg.agents?.defaults?.imageModel)) {
     addModel(out, f, "agents.defaults.imageModel.fallbacks");
   }