diff --git a/src/agents/pi-embedded-runner/compact.ts b/src/agents/pi-embedded-runner/compact.ts
index 2dc4c5325..0665f87df 100644
--- a/src/agents/pi-embedded-runner/compact.ts
+++ b/src/agents/pi-embedded-runner/compact.ts
@@ -28,6 +28,7 @@ import { makeBootstrapWarn, resolveBootstrapContextForRun } from "../bootstrap-f
 import { resolveOpenClawDocsPath } from "../docs-path.js";
 import type { ExecElevatedDefaults } from "../bash-tools.js";
 import { DEFAULT_MODEL, DEFAULT_PROVIDER } from "../defaults.js";
+import { isCliProvider } from "../model-selection.js";
 import { getApiKeyForModel, resolveModelAuthMode } from "../model-auth.js";
 import { ensureOpenClawModelsJson } from "../models-config.js";
 import {
@@ -114,6 +115,15 @@ export async function compactEmbeddedPiSessionDirect(
 
   const provider = (params.provider ?? DEFAULT_PROVIDER).trim() || DEFAULT_PROVIDER;
   const modelId = (params.model ?? DEFAULT_MODEL).trim() || DEFAULT_MODEL;
+
+  if (isCliProvider(provider, params.config)) {
+    return {
+      ok: false,
+      compacted: false,
+      reason: `Compaction is not supported for CLI providers (${provider}/${modelId}). Switch to an API-based model to use /compact.`,
+    };
+  }
+
   const agentDir = params.agentDir ?? resolveOpenClawAgentDir();
   await ensureOpenClawModelsJson(params.config, agentDir);
   const { model, error, authStorage, modelRegistry } = resolveModel(