diff --git a/src/extension-host/plugin-registry-compat.test.ts b/src/extension-host/plugin-registry-compat.test.ts
new file mode 100644
index 00000000000..c45313fb95f
--- /dev/null
+++ b/src/extension-host/plugin-registry-compat.test.ts
@@ -0,0 +1,92 @@
+import { describe, expect, it, vi } from "vitest";
+import { clearPluginCommands } from "../plugins/commands.js";
+import { createEmptyPluginRegistry, type PluginRecord } from "../plugins/registry.js";
+import {
+  resolveExtensionHostCommandCompatibility,
+  resolveExtensionHostProviderCompatibility,
+} from "./plugin-registry-compat.js";
+
+function createRecord(): PluginRecord {
+  return {
+    id: "demo",
+    name: "Demo",
+    source: "/plugins/demo.ts",
+    origin: "workspace",
+    enabled: true,
+    status: "loaded",
+    toolNames: [],
+    hookNames: [],
+    channelIds: [],
+    providerIds: [],
+    gatewayMethods: [],
+    cliCommands: [],
+    services: [],
+    commands: [],
+    httpRoutes: 0,
+    hookCount: 0,
+    configSchema: false,
+  };
+}
+
+describe("extension host plugin registry compatibility", () => {
+  it("normalizes provider registration through the host-owned compatibility helper", () => {
+    const result = resolveExtensionHostProviderCompatibility({
+      registry: createEmptyPluginRegistry(),
+      record: createRecord(),
+      provider: {
+        id: " demo-provider ",
+        label: " Demo Provider ",
+        auth: [{ id: " api-key ", label: " API Key " }],
+      } as never,
+    });
+
+    expect(result).toMatchObject({
+      ok: true,
+      providerId: "demo-provider",
+      entry: {
+        provider: {
+          id: "demo-provider",
+          label: "Demo Provider",
+          auth: [{ id: "api-key", label: "API Key" }],
+        },
+      },
+    });
+  });
+
+  it("reports duplicate command registration through the host-owned compatibility helper", () => {
+    clearPluginCommands();
+    const registry = createEmptyPluginRegistry();
+    const record = createRecord();
+
+    const first = resolveExtensionHostCommandCompatibility({
+      registry,
+      record,
+      command: {
+        name: "demo",
+        description: "first",
+        handler: vi.fn(async () => ({ handled: true })),
+      },
+    });
+    const second = resolveExtensionHostCommandCompatibility({
+      registry,
+      record,
+      command: {
+        name: "demo",
+        description: "second",
+        handler: vi.fn(async () => ({ handled: true })),
+      },
+    });
+
+    expect(first.ok).toBe(true);
+    expect(second.ok).toBe(false);
+    expect(registry.diagnostics).toContainEqual(
+      expect.objectContaining({
+        level: "error",
+        pluginId: "demo",
+        message: 'command registration failed: Command "demo" already registered by plugin "demo"',
+      }),
+    );
+
+    clearPluginCommands();
+  });
+});
diff --git a/src/extension-host/plugin-registry-compat.ts b/src/extension-host/plugin-registry-compat.ts
new file mode 100644
index 00000000000..5a794ad59db
--- /dev/null
+++ b/src/extension-host/plugin-registry-compat.ts
@@ -0,0 +1,116 @@
+import { registerPluginCommand } from "../plugins/commands.js";
+import { normalizeRegisteredProvider } from "../plugins/provider-validation.js";
+import type { PluginRecord, PluginRegistry } from "../plugins/registry.js";
+import type {
+  OpenClawPluginCommandDefinition,
+  PluginDiagnostic,
+  ProviderPlugin,
+} from "../plugins/types.js";
+import {
+  type ExtensionHostCommandRegistration,
+  type ExtensionHostProviderRegistration,
+  resolveExtensionCommandRegistration,
+  resolveExtensionProviderRegistration,
+} from "./runtime-registrations.js";
+
+export function pushExtensionHostRegistryDiagnostic(params: {
+  registry: PluginRegistry;
+  level: PluginDiagnostic["level"];
+  pluginId: string;
+  source: string;
+  message: string;
+}) {
+  params.registry.diagnostics.push({
+    level: params.level,
+    pluginId: params.pluginId,
+    source: params.source,
+    message: params.message,
+  });
+}
+
+export function resolveExtensionHostProviderCompatibility(params: {
+  registry: PluginRegistry;
+  record: PluginRecord;
+  provider: ProviderPlugin;
+}):
+  | {
+      ok: true;
+      providerId: string;
+      entry: ExtensionHostProviderRegistration;
+    }
+  | { ok: false } {
+  const pushDiagnostic = (diag: PluginDiagnostic) => {
+    params.registry.diagnostics.push(diag);
+  };
+
+  const normalizedProvider = normalizeRegisteredProvider({
+    pluginId: params.record.id,
+    source: params.record.source,
+    provider: params.provider,
+    pushDiagnostic,
+  });
+  if (!normalizedProvider) {
+    return { ok: false };
+  }
+
+  const result = resolveExtensionProviderRegistration({
+    existing: params.registry.providers,
+    ownerPluginId: params.record.id,
+    ownerSource: params.record.source,
+    provider: normalizedProvider,
+  });
+  if (!result.ok) {
+    pushExtensionHostRegistryDiagnostic({
+      registry: params.registry,
+      level: "error",
+      pluginId: params.record.id,
+      source: params.record.source,
+      message: result.message,
+    });
+    return { ok: false };
+  }
+
+  return result;
+}
+
+export function resolveExtensionHostCommandCompatibility(params: {
+  registry: PluginRegistry;
+  record: PluginRecord;
+  command: OpenClawPluginCommandDefinition;
+}):
+  | {
+      ok: true;
+      commandName: string;
+      entry: ExtensionHostCommandRegistration;
+    }
+  | { ok: false } {
+  const normalized = resolveExtensionCommandRegistration({
+    ownerPluginId: params.record.id,
+    ownerSource: params.record.source,
+    command: params.command,
+  });
+  if (!normalized.ok) {
+    pushExtensionHostRegistryDiagnostic({
+      registry: params.registry,
+      level: "error",
+      pluginId: params.record.id,
+      source: params.record.source,
+      message: normalized.message,
+    });
+    return { ok: false };
+  }
+
+  const result = registerPluginCommand(params.record.id, normalized.entry.command);
+  if (!result.ok) {
+    pushExtensionHostRegistryDiagnostic({
+      registry: params.registry,
+      level: "error",
+      pluginId: params.record.id,
+      source: params.record.source,
+      message: `command registration failed: ${result.error}`,
+    });
+    return { ok: false };
+  }
+
+  return normalized;
+}
diff --git a/src/extension-host/plugin-registry.ts b/src/extension-host/plugin-registry.ts
index f68acbfb1c9..63a4764a12a 100644
--- a/src/extension-host/plugin-registry.ts
+++ b/src/extension-host/plugin-registry.ts
@@ -22,20 +22,16 @@ import {
 import {
   resolveExtensionChannelRegistration,
   resolveExtensionCliRegistration,
-  resolveExtensionCommandRegistration,
   resolveExtensionContextEngineRegistration,
   resolveExtensionGatewayMethodRegistration,
   resolveExtensionLegacyHookRegistration,
   resolveExtensionHttpRouteRegistration,
-  resolveExtensionProviderRegistration,
   resolveExtensionServiceRegistration,
   resolveExtensionToolRegistration,
   resolveExtensionTypedHookRegistration,
 } from "../extension-host/runtime-registrations.js";
 import type { GatewayRequestHandler } from "../gateway/server-methods/types.js";
 import { registerInternalHook } from "../hooks/internal-hooks.js";
-import { registerPluginCommand } from "../plugins/commands.js";
-import { normalizeRegisteredProvider } from "../plugins/provider-validation.js";
 import type { PluginRecord, PluginRegistry, PluginRegistryParams } from "../plugins/registry.js";
 import type {
   PluginDiagnostic,
@@ -52,33 +48,22 @@ import type {
   ProviderPlugin,
   PluginHookRegistration as TypedPluginHookRegistration,
 } from "../plugins/types.js";
+import {
+  pushExtensionHostRegistryDiagnostic,
+  resolveExtensionHostCommandCompatibility,
+  resolveExtensionHostProviderCompatibility,
+} from "./plugin-registry-compat.js";
 
 type PluginTypedHookPolicy = {
   allowPromptInjection?: boolean;
 };
 
-function pushExtensionHostRegistryDiagnostic(params: {
-  registry: PluginRegistry;
-  level: PluginDiagnostic["level"];
-  pluginId: string;
-  source: string;
-  message: string;
-}) {
-  params.registry.diagnostics.push({
-    level: params.level,
-    pluginId: params.pluginId,
-    source: params.source,
-    message: params.message,
-  });
-}
-
 export function createExtensionHostPluginRegistry(params: {
   registry: PluginRegistry;
   registryParams: PluginRegistryParams;
 }) {
   const { registry, registryParams } = params;
   const coreGatewayMethods = new Set(Object.keys(registryParams.coreGatewayHandlers ?? {}));
-
   const pushDiagnostic = (diag: PluginDiagnostic) => {
     registry.diagnostics.push(diag);
   };
@@ -231,29 +216,12 @@ export function createExtensionHostPluginRegistry(params: {
   };
 
   const registerProvider = (record: PluginRecord, provider: ProviderPlugin) => {
-    const normalizedProvider = normalizeRegisteredProvider({
-      pluginId: record.id,
-      source: record.source,
+    const result = resolveExtensionHostProviderCompatibility({
+      registry,
+      record,
       provider,
-      pushDiagnostic,
-    });
-    if (!normalizedProvider) {
-      return;
-    }
-    const result = resolveExtensionProviderRegistration({
-      existing: registry.providers,
-      ownerPluginId: record.id,
-      ownerSource: record.source,
-      provider: normalizedProvider,
     });
     if (!result.ok) {
-      pushExtensionHostRegistryDiagnostic({
-        registry,
-        level: "error",
-        pluginId: record.id,
-        source: record.source,
-        message: result.message,
-      });
       return;
     }
     addExtensionProviderRegistration({
@@ -301,34 +269,10 @@ export function createExtensionHostPluginRegistry(params: {
   };
 
   const registerCommand = (record: PluginRecord, command: OpenClawPluginCommandDefinition) => {
-    const normalized = resolveExtensionCommandRegistration({
-      ownerPluginId: record.id,
-      ownerSource: record.source,
-      command,
-    });
+    const normalized = resolveExtensionHostCommandCompatibility({ registry, record, command });
     if (!normalized.ok) {
-      pushExtensionHostRegistryDiagnostic({
-        registry,
-        level: "error",
-        pluginId: record.id,
-        source: record.source,
-        message: normalized.message,
-      });
       return;
     }
-
-    const result = registerPluginCommand(record.id, normalized.entry.command);
-    if (!result.ok) {
-      pushExtensionHostRegistryDiagnostic({
-        registry,
-        level: "error",
-        pluginId: record.id,
-        source: record.source,
-        message: `command registration failed: ${result.error}`,
-      });
-      return;
-    }
-
     addExtensionCommandRegistration({
       registry,
       record,